33 files changed, 1092 insertions, 317 deletions
diff --git a/Cargo.lock b/Cargo.lock
index 3b8df0c8a..db09967ba 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -87,6 +87,11 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
 name = "bitflags"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+[[package]]
+name = "bitflags"
 version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -110,6 +115,15 @@ version = "1.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
+name = "bytes"
+version = "0.4.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "byteorder 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "iovec 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+[[package]]
 name = "cargo_metadata"
 version = "0.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -336,6 +350,16 @@ version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
+name = "filetime"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.48 (registry+https://github.com/rust-lang/crates.io-index)",
+ "redox_syscall 0.1.51 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+[[package]]
 name = "flexi_logger"
 version = "0.10.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -352,6 +376,24 @@ version = "1.0.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
+name = "fsevent"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "bitflags 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "fsevent-sys 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.48 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+[[package]]
+name = "fsevent-sys"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "libc 0.2.48 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+[[package]]
 name = "fst"
 version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -375,6 +417,11 @@ version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
+name = "futures"
+version = "0.1.25"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+[[package]]
 name = "gen_lsp_server"
 version = "0.1.0"
 dependencies = [
@@ -437,6 +484,28 @@ version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
+name = "inotify"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "futures 0.1.25 (registry+https://github.com/rust-lang/crates.io-index)",
+ "inotify-sys 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.48 (registry+https://github.com/rust-lang/crates.io-index)",
+ "mio 0.6.16 (registry+https://github.com/rust-lang/crates.io-index)",
+ "tokio-io 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "tokio-reactor 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+[[package]]
+name = "inotify-sys"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "libc 0.2.48 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+[[package]]
 name = "insta"
 version = "0.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -456,6 +525,15 @@ dependencies = [
 ]
 [[package]]
+name = "iovec"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "libc 0.2.48 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+[[package]]
 name = "itertools"
 version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -474,11 +552,25 @@ version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
+name = "kernel32-sys"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi-build 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+[[package]]
 name = "lazy_static"
 version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
+name = "lazycell"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+[[package]]
 name = "libc"
 version = "0.2.48"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -511,7 +603,7 @@ version = "0.55.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "num-derive 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-derive 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
 "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde 1.0.85 (registry+https://github.com/rust-lang/crates.io-index)",
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 [[package]]
+name = "mio"
+version = "0.6.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "fuchsia-zircon 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "fuchsia-zircon-sys 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "iovec 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazycell 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.48 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "miow 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "net2 0.2.33 (registry+https://github.com/rust-lang/crates.io-index)",
+ "slab 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
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+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
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+ "mio 0.6.16 (registry+https://github.com/rust-lang/crates.io-index)",
+ "slab 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "net2 0.2.33 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ws2_32-sys 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
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+ "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
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+[[package]]
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+ "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
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+[[package]]
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- "salsa 0.10.0-alpha4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "salsa 0.10.0-alpha5 (registry+https://github.com/rust-lang/crates.io-index)",
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@@ -849,7 +1008,11 @@ name = "ra_vfs"
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+ "drop_bomb 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
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@@ -1199,6 +1362,11 @@ dependencies = [
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@@ -1382,6 +1550,42 @@ dependencies = [
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@@ -1565,6 +1774,11 @@ dependencies = [
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+[[package]]
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+[[package]]
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+"checksum futures 0.1.25 (registry+https://github.com/rust-lang/crates.io-index)" = "49e7653e374fe0d0c12de4250f0bdb60680b8c80eed558c5c7538eec9c89e21b"
 "checksum generic-array 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ef25c5683767570c2bbd7deba372926a55eaae9982d7726ee2a1050239d45b9d"
 "checksum glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "8be18de09a56b60ed0edf84bc9df007e30040691af7acd1c41874faac5895bfb"
 "checksum heck 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "20564e78d53d2bb135c343b3f47714a56af2061f1c928fdb541dc7b9fdd94205"
@@ -1645,11 +1874,16 @@ dependencies = [
 "checksum idna 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "38f09e0f0b1fb55fdee1f17470ad800da77af5186a1a76c026b679358b7e844e"
 "checksum im 12.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "0627d417829c1d763d602687634869f254fc79f7e22dea6c824dab993db857e4"
 "checksum indexmap 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7e81a7c05f79578dbc15793d8b619db9ba32b4577003ef3af1a91c416798c58d"
+"checksum inotify 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)" = "40b54539f3910d6f84fbf9a643efd6e3aa6e4f001426c0329576128255994718"
+"checksum inotify-sys 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "e74a1aa87c59aeff6ef2cc2fa62d41bc43f54952f55652656b18a02fd5e356c0"
 "checksum insta 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)" = "6ff57d9cbc4664b54a972c321155c7703794bc0f5c9944f29c36f40d10d626f3"
+"checksum iovec 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "dbe6e417e7d0975db6512b90796e8ce223145ac4e33c377e4a42882a0e88bb08"
 "checksum itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5b8467d9c1cebe26feb08c640139247fac215782d35371ade9a2136ed6085358"
 "checksum itoa 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)" = "1306f3464951f30e30d12373d31c79fbd52d236e5e896fd92f96ec7babbbe60b"
 "checksum join_to_string 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "4dc7a5290e8c2606ce2be49f456d50f69173cb96d1541e4f66e34ac8b331a98f"
+"checksum kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7507624b29483431c0ba2d82aece8ca6cdba9382bff4ddd0f7490560c056098d"
 "checksum lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "a374c89b9db55895453a74c1e38861d9deec0b01b405a82516e9d5de4820dea1"
+"checksum lazycell 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "b294d6fa9ee409a054354afc4352b0b9ef7ca222c69b8812cbea9e7d2bf3783f"
 "checksum libc 0.2.48 (registry+https://github.com/rust-lang/crates.io-index)" = "e962c7641008ac010fa60a7dfdc1712449f29c44ef2d4702394aea943ee75047"
 "checksum linked-hash-map 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "70fb39025bc7cdd76305867c4eccf2f2dcf6e9a57f5b21a93e1c2d86cd03ec9e"
 "checksum lock_api 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "62ebf1391f6acad60e5c8b43706dde4582df75c06698ab44511d15016bc2442c"
@@ -1660,8 +1894,13 @@ dependencies = [
 "checksum memchr 2.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "e1dd4eaac298c32ce07eb6ed9242eda7d82955b9170b7d6db59b2e02cc63fcb8"
 "checksum memmap 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)" = "e2ffa2c986de11a9df78620c01eeaaf27d94d3ff02bf81bfcca953102dd0c6ff"
 "checksum memoffset 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "0f9dc261e2b62d7a622bf416ea3c5245cdd5d9a7fcc428c0d06804dfce1775b3"
+"checksum mio 0.6.16 (registry+https://github.com/rust-lang/crates.io-index)" = "71646331f2619b1026cc302f87a2b8b648d5c6dd6937846a16cc8ce0f347f432"
+"checksum mio-extras 2.0.5 (registry+https://github.com/rust-lang/crates.io-index)" = "46e73a04c2fa6250b8d802134d56d554a9ec2922bf977777c805ea5def61ce40"
+"checksum miow 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "8c1f2f3b1cf331de6896aabf6e9d55dca90356cc9960cca7eaaf408a355ae919"
+"checksum net2 0.2.33 (registry+https://github.com/rust-lang/crates.io-index)" = "42550d9fb7b6684a6d404d9fa7250c2eb2646df731d1c06afc06dcee9e1bcf88"
 "checksum nodrop 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)" = "2f9667ddcc6cc8a43afc9b7917599d7216aa09c463919ea32c59ed6cac8bc945"
-"checksum num-derive 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8af1847c907c2f04d7bfd572fb25bbb4385c637fe5be163cf2f8c5d778fe1e7d"
+"checksum notify 4.0.7 (registry+https://github.com/rust-lang/crates.io-index)" = "c968cf37cf949114b00d51b0b23536d1c3a4a3963767cf4c969c65a6af78dc7d"
+"checksum num-derive 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)" = "d9fe8fcafd1b86a37ce8a1cfa15ae504817e0c8c2e7ad42767371461ac1d316d"
 "checksum num-integer 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)" = "e83d528d2677f0518c570baf2b7abdcf0cd2d248860b68507bdcb3e91d4c0cea"
 "checksum num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "0b3a5d7cc97d6d30d8b9bc8fa19bf45349ffe46241e8816f50f62f6d6aaabee1"
 "checksum num_cpus 1.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5a69d464bdc213aaaff628444e99578ede64e9c854025aa43b9796530afa9238"
@@ -1704,8 +1943,8 @@ dependencies = [
 "checksum rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "138e3e0acb6c9fb258b19b67cb8abd63c00679d2851805ea151465464fe9030a"
 "checksum rusty-fork 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "9591f190d2852720b679c21f66ad929f9f1d7bb09d1193c26167586029d8489c"
 "checksum ryu 0.2.7 (registry+https://github.com/rust-lang/crates.io-index)" = "eb9e9b8cde282a9fe6a42dd4681319bfb63f121b8a8ee9439c6f4107e58a46f7"
-"checksum salsa 0.10.0-alpha4 (registry+https://github.com/rust-lang/crates.io-index)" = "3f442595eae948da8fbb2aa1e13940d9d2d70031753a27a5d1434f91b706ff12"
+"checksum salsa 0.10.0-alpha5 (registry+https://github.com/rust-lang/crates.io-index)" = "8b5e2535d707dc5ced81106d3b71d806cfeef8a6e8a567472fde7ffd56b770dd"
-"checksum salsa-macros 0.10.0-alpha4 (registry+https://github.com/rust-lang/crates.io-index)" = "2e6c1a1bee4eb44881438e80c1a26db1c3b957b6cc51765615d429019babdec2"
+"checksum salsa-macros 0.10.0-alpha5 (registry+https://github.com/rust-lang/crates.io-index)" = "e7c5da4c649f6d4fc1864fcd9a379b1f7c6d570b278559c84a6e15981c949cc6"
 "checksum same-file 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "8f20c4be53a8a1ff4c1f1b2bd14570d2f634628709752f0702ecdd2b3f9a5267"
 "checksum scopeguard 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "94258f53601af11e6a49f722422f6e3425c52b06245a5cf9bc09908b174f5e27"
 "checksum semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1d7eb9ef2c18661902cc47e535f9bc51b78acd254da71d375c2f6720d9a40403"
@@ -1715,6 +1954,7 @@ dependencies = [
 "checksum serde_json 1.0.37 (registry+https://github.com/rust-lang/crates.io-index)" = "4b90a9fbe1211e57d3e1c15670f1cb00802988fb23a1a4aad7a2b63544f1920e"
 "checksum serde_yaml 0.8.8 (registry+https://github.com/rust-lang/crates.io-index)" = "0887a8e097a69559b56aa2526bf7aff7c3048cf627dff781f0b56a6001534593"
 "checksum sha-1 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "51b9d1f3b5de8a167ab06834a7c883bd197f2191e1dda1a22d9ccfeedbf9aded"
+"checksum slab 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)" = "c111b5bd5695e56cffe5129854aa230b39c93a305372fdbb2668ca2394eea9f8"
 "checksum slug 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "b3bc762e6a4b6c6fcaade73e77f9ebc6991b676f88bb2358bddb56560f073373"
 "checksum smallvec 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)" = "88aea073965ab29f6edb5493faf96ad662fb18aa9eeb186a3b7057951605ed15"
 "checksum smol_str 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)" = "9af1035bc5d742ab6b7ab16713e41cc2ffe78cb474f6f43cd696b2d16052007e"
@@ -1733,6 +1973,9 @@ dependencies = [
 "checksum thread_local 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "c6b53e329000edc2b34dbe8545fd20e55a333362d0a321909685a19bd28c3f1b"
 "checksum threadpool 1.7.1 (registry+https://github.com/rust-lang/crates.io-index)" = "e2f0c90a5f3459330ac8bc0d2f879c693bb7a2f59689c1083fc4ef83834da865"
 "checksum time 0.1.42 (registry+https://github.com/rust-lang/crates.io-index)" = "db8dcfca086c1143c9270ac42a2bbd8a7ee477b78ac8e45b19abfb0cbede4b6f"
+"checksum tokio-executor 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "30c6dbf2d1ad1de300b393910e8a3aa272b724a400b6531da03eed99e329fbf0"
+"checksum tokio-io 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)" = "b53aeb9d3f5ccf2ebb29e19788f96987fa1355f8fe45ea193928eaaaf3ae820f"
+"checksum tokio-reactor 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)" = "afbcdb0f0d2a1e4c440af82d7bbf0bf91a8a8c0575bcd20c05d15be7e9d3a02f"
 "checksum typenum 1.10.0 (registry+https://github.com/rust-lang/crates.io-index)" = "612d636f949607bdf9b123b4a6f6d966dedf3ff669f7f045890d3a4a73948169"
 "checksum ucd-trie 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "71a9c5b1fe77426cf144cc30e49e955270f5086e31a6441dfa8b32efc09b9d77"
 "checksum ucd-util 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "535c204ee4d8434478593480b8f86ab45ec9aae0e83c568ca81abf0fd0e88f86"
@@ -1757,8 +2000,11 @@ dependencies = [
 "checksum void 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "6a02e4885ed3bc0f2de90ea6dd45ebcbb66dacffe03547fadbb0eeae2770887d"
 "checksum wait-timeout 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "b9f3bf741a801531993db6478b95682117471f76916f5e690dd8d45395b09349"
 "checksum walkdir 2.2.7 (registry+https://github.com/rust-lang/crates.io-index)" = "9d9d7ed3431229a144296213105a390676cc49c9b6a72bd19f3176c98e129fa1"
+"checksum winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)" = "167dc9d6949a9b857f3451275e911c3f44255842c1f7a76f33c55103a909087a"
 "checksum winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "92c1eb33641e276cfa214a0522acad57be5c56b10cb348b3c5117db75f3ac4b0"
+"checksum winapi-build 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "2d315eee3b34aca4797b2da6b13ed88266e6d612562a0c46390af8299fc699bc"
 "checksum winapi-i686-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
 "checksum winapi-util 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "afc5508759c5bf4285e61feb862b6083c8480aec864fa17a81fdec6f69b461ab"
 "checksum winapi-x86_64-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
+"checksum ws2_32-sys 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "d59cefebd0c892fa2dd6de581e937301d8552cb44489cdff035c6187cb63fa5e"
 "checksum yaml-rust 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)" = "95acf0db5515d07da9965ec0e0ba6cc2d825e2caeb7303b66ca441729801254e"
diff --git a/crates/ra_db/src/lib.rs b/crates/ra_db/src/lib.rs
index 3a0aa7d24..6e17f33f0 100644
--- a/crates/ra_db/src/lib.rs
+++ b/crates/ra_db/src/lib.rs
@@ -20,7 +20,7 @@ pub use crate::{
    loc2id::LocationIntener,
 };
-pub trait BaseDatabase: salsa::Database + panic::RefUnwindSafe {
+pub trait CheckCanceled: salsa::Database + panic::RefUnwindSafe {
    /// Aborts current query if there are pending changes.
    ///
    /// rust-analyzer needs to be able to answer semantic questions about the
@@ -63,11 +63,15 @@ pub struct FileRange {
    pub range: TextRange,
 }
-#[salsa::query_group(FilesDatabaseStorage)]
+/// Database which stores all significant input facts: source code and project
-pub trait FilesDatabase: salsa::Database {
+/// model. Everything else in rust-analyzer is derived from these queries.
+#[salsa::query_group(SourceDatabaseStorage)]
+pub trait SourceDatabase: salsa::Database + CheckCanceled {
    /// Text of the file.
    #[salsa::input]
    fn file_text(&self, file_id: FileId) -> Arc<String>;
+    // Parses the file into the syntax tree.
+    fn parse(&self, file_id: FileId) -> TreeArc<SourceFile>;
    /// Path to a file, relative to the root of its source root.
    #[salsa::input]
    fn file_relative_path(&self, file_id: FileId) -> RelativePathBuf;
@@ -78,20 +82,12 @@ pub trait FilesDatabase: salsa::Database {
    #[salsa::input]
    fn source_root(&self, id: SourceRootId) -> Arc<SourceRoot>;
    fn source_root_crates(&self, id: SourceRootId) -> Arc<Vec<CrateId>>;
-    /// The set of "local" (that is, from the current workspace) roots.
-    /// Files in local roots are assumed to change frequently.
-    #[salsa::input]
-    fn local_roots(&self) -> Arc<Vec<SourceRootId>>;
-    /// The set of roots for crates.io libraries.
-    /// Files in libraries are assumed to never change.
-    #[salsa::input]
-    fn library_roots(&self) -> Arc<Vec<SourceRootId>>;
    /// The crate graph.
    #[salsa::input]
    fn crate_graph(&self) -> Arc<CrateGraph>;
 }
-fn source_root_crates(db: &impl FilesDatabase, id: SourceRootId) -> Arc<Vec<CrateId>> {
+fn source_root_crates(db: &impl SourceDatabase, id: SourceRootId) -> Arc<Vec<CrateId>> {
    let root = db.source_root(id);
    let graph = db.crate_graph();
    let res = root
@@ -102,12 +98,7 @@ fn source_root_crates(db: &impl FilesDatabase, id: SourceRootId) -> Arc<Vec<Crat
    Arc::new(res)
 }
-#[salsa::query_group(SyntaxDatabaseStorage)]
+fn parse(db: &impl SourceDatabase, file_id: FileId) -> TreeArc<SourceFile> {
-pub trait SyntaxDatabase: FilesDatabase + BaseDatabase {
-    fn source_file(&self, file_id: FileId) -> TreeArc<SourceFile>;
-}
-fn source_file(db: &impl SyntaxDatabase, file_id: FileId) -> TreeArc<SourceFile> {
    let text = db.file_text(file_id);
    SourceFile::parse(&*text)
 }
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index dfbf41bd6..5df4bd4a1 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -1,7 +1,7 @@
 use std::sync::Arc;
 use ra_syntax::{SyntaxNode, TreeArc, SourceFile};
-use ra_db::{SyntaxDatabase, CrateId, salsa};
+use ra_db::{SourceDatabase, CrateId, salsa};
 use crate::{
    MacroCallId, HirFileId,
@@ -19,9 +19,9 @@ use crate::{
 };
 #[salsa::query_group(HirDatabaseStorage)]
-pub trait HirDatabase: SyntaxDatabase + AsRef<HirInterner> {
+pub trait HirDatabase: SourceDatabase + AsRef<HirInterner> {
-    #[salsa::invoke(HirFileId::hir_source_file)]
+    #[salsa::invoke(HirFileId::hir_parse)]
-    fn hir_source_file(&self, file_id: HirFileId) -> TreeArc<SourceFile>;
+    fn hir_parse(&self, file_id: HirFileId) -> TreeArc<SourceFile>;
    #[salsa::invoke(crate::macros::expand_macro_invocation)]
    fn expand_macro_invocation(&self, invoc: MacroCallId) -> Option<Arc<MacroExpansion>>;
diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index 5272656ec..7dd4b540e 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -86,12 +86,9 @@ impl HirFileId {
        }
    }
-    pub(crate) fn hir_source_file(
+    pub(crate) fn hir_parse(db: &impl HirDatabase, file_id: HirFileId) -> TreeArc<SourceFile> {
-        db: &impl HirDatabase,
-        file_id: HirFileId,
-    ) -> TreeArc<SourceFile> {
        match file_id.0 {
-            HirFileIdRepr::File(file_id) => db.source_file(file_id),
+            HirFileIdRepr::File(file_id) => db.parse(file_id),
            HirFileIdRepr::Macro(m) => {
                if let Some(exp) = db.expand_macro_invocation(m) {
                    return exp.file();
@@ -370,7 +367,7 @@ impl SourceFileItems {
            self.arena.iter().map(|(_id, i)| i).collect::<Vec<_>>(),
        );
    }
-    pub fn id_of_source_file(&self) -> SourceFileItemId {
+    pub fn id_of_parse(&self) -> SourceFileItemId {
        let (id, _syntax) = self.arena.iter().next().unwrap();
        id
    }
diff --git a/crates/ra_hir/src/mock.rs b/crates/ra_hir/src/mock.rs
index 2dc252b1e..7da15eca0 100644
--- a/crates/ra_hir/src/mock.rs
+++ b/crates/ra_hir/src/mock.rs
@@ -2,7 +2,7 @@ use std::{sync::Arc, panic};
 use parking_lot::Mutex;
 use ra_db::{
-    BaseDatabase, FilePosition, FileId, CrateGraph, SourceRoot, SourceRootId, FilesDatabase, salsa,
+    CheckCanceled, FilePosition, FileId, CrateGraph, SourceRoot, SourceRootId, SourceDatabase, salsa,
 };
 use relative_path::RelativePathBuf;
 use test_utils::{parse_fixture, CURSOR_MARKER, extract_offset};
@@ -11,11 +11,7 @@ use crate::{db, HirInterner};
 pub const WORKSPACE: SourceRootId = SourceRootId(0);
-#[salsa::database(
+#[salsa::database(ra_db::SourceDatabaseStorage, db::HirDatabaseStorage)]
-    ra_db::FilesDatabaseStorage,
-    ra_db::SyntaxDatabaseStorage,
-    db::HirDatabaseStorage
-)]
 #[derive(Debug)]
 pub(crate) struct MockDatabase {
    events: Mutex<Option<Vec<salsa::Event<MockDatabase>>>>,
@@ -144,8 +140,6 @@ impl Default for MockDatabase {
            file_counter: 0,
        };
        db.set_crate_graph(Default::default());
-        db.set_local_roots(Default::default());
-        db.set_library_roots(Default::default());
        db
    }
 }
@@ -161,7 +155,7 @@ impl salsa::ParallelDatabase for MockDatabase {
    }
 }
-impl BaseDatabase for MockDatabase {}
+impl CheckCanceled for MockDatabase {}
 impl AsRef<HirInterner> for MockDatabase {
    fn as_ref(&self) -> &HirInterner {
diff --git a/crates/ra_hir/src/nameres/lower.rs b/crates/ra_hir/src/nameres/lower.rs
index b4fe99ea7..1d77548f3 100644
--- a/crates/ra_hir/src/nameres/lower.rs
+++ b/crates/ra_hir/src/nameres/lower.rs
@@ -129,7 +129,7 @@ impl LoweredModule {
                    let id = loc.id(db);
                    let file_id = HirFileId::from(id);
                    //FIXME: expand recursively
-                    for item in db.hir_source_file(file_id).items() {
+                    for item in db.hir_parse(file_id).items() {
                        self.add_def_id(source_map, db, module, file_id, item);
                    }
                }
diff --git a/crates/ra_hir/src/nameres/tests.rs b/crates/ra_hir/src/nameres/tests.rs
index 24936976c..e72781f51 100644
--- a/crates/ra_hir/src/nameres/tests.rs
+++ b/crates/ra_hir/src/nameres/tests.rs
@@ -1,6 +1,6 @@
 use std::sync::Arc;
-use ra_db::{CrateGraph, SourceRootId, FilesDatabase};
+use ra_db::{CrateGraph, SourceRootId, SourceDatabase};
 use relative_path::RelativePath;
 use test_utils::{assert_eq_text, covers};
diff --git a/crates/ra_hir/src/query_definitions.rs b/crates/ra_hir/src/query_definitions.rs
index cf8c7e435..61c93a964 100644
--- a/crates/ra_hir/src/query_definitions.rs
+++ b/crates/ra_hir/src/query_definitions.rs
@@ -23,7 +23,7 @@ pub(super) fn fn_scopes(db: &impl HirDatabase, func: Function) -> Arc<FnScopes>
 }
 pub(super) fn file_items(db: &impl HirDatabase, file_id: HirFileId) -> Arc<SourceFileItems> {
-    let source_file = db.hir_source_file(file_id);
+    let source_file = db.hir_parse(file_id);
    let res = SourceFileItems::new(file_id, &source_file);
    Arc::new(res)
 }
@@ -34,10 +34,7 @@ pub(super) fn file_item(
 ) -> TreeArc<SyntaxNode> {
    match source_item_id.item_id {
        Some(id) => db.file_items(source_item_id.file_id)[id].to_owned(),
-        None => db
+        None => db.hir_parse(source_item_id.file_id).syntax().to_owned(),
-            .hir_source_file(source_item_id.file_id)
-            .syntax()
-            .to_owned(),
    }
 }
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index dbe040805..c0b3f1cd4 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -43,7 +43,7 @@ pub fn module_from_declaration(
 /// Locates the module by position in the source code.
 pub fn module_from_position(db: &impl HirDatabase, position: FilePosition) -> Option<Module> {
-    let file = db.source_file(position.file_id);
+    let file = db.parse(position.file_id);
    match find_node_at_offset::<ast::Module>(file.syntax(), position.offset) {
        Some(m) if !m.has_semi() => module_from_inline(db, position.file_id.into(), m),
        _ => module_from_file_id(db, position.file_id.into()),
@@ -95,7 +95,7 @@ fn module_from_source(db: &impl HirDatabase, source: SourceItemId) -> Option<Mod
 }
 pub fn function_from_position(db: &impl HirDatabase, position: FilePosition) -> Option<Function> {
-    let file = db.source_file(position.file_id);
+    let file = db.parse(position.file_id);
    let fn_def = find_node_at_offset::<ast::FnDef>(file.syntax(), position.offset)?;
    function_from_source(db, position.file_id, fn_def)
 }
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index 389bdaf23..e0b0689f8 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -1,7 +1,7 @@
 use std::sync::Arc;
 use std::fmt::Write;
-use ra_db::{SyntaxDatabase, salsa::Database};
+use ra_db::{SourceDatabase, salsa::Database};
 use ra_syntax::ast::{self, AstNode};
 use crate::{
@@ -547,7 +547,7 @@ fn quux() {
 fn infer(content: &str) -> String {
    let (db, _, file_id) = MockDatabase::with_single_file(content);
-    let source_file = db.source_file(file_id);
+    let source_file = db.parse(file_id);
    let mut acc = String::new();
    for fn_def in source_file
        .syntax()
diff --git a/crates/ra_ide_api/src/call_info.rs b/crates/ra_ide_api/src/call_info.rs
index 0449c1902..3267fff96 100644
--- a/crates/ra_ide_api/src/call_info.rs
+++ b/crates/ra_ide_api/src/call_info.rs
@@ -1,4 +1,4 @@
-use ra_db::SyntaxDatabase;
+use ra_db::SourceDatabase;
 use ra_syntax::{
    AstNode, SyntaxNode, TextUnit, TextRange,
    SyntaxKind::FN_DEF,
@@ -10,7 +10,7 @@ use crate::{FilePosition, CallInfo, db::RootDatabase};
 /// Computes parameter information for the given call expression.
 pub(crate) fn call_info(db: &RootDatabase, position: FilePosition) -> Option<CallInfo> {
-    let file = db.source_file(position.file_id);
+    let file = db.parse(position.file_id);
    let syntax = file.syntax();
    // Find the calling expression and it's NameRef
@@ -22,7 +22,7 @@ pub(crate) fn call_info(db: &RootDatabase, position: FilePosition) -> Option<Cal
    let symbol = file_symbols
        .into_iter()
        .find(|it| it.ptr.kind() == FN_DEF)?;
-    let fn_file = db.source_file(symbol.file_id);
+    let fn_file = db.parse(symbol.file_id);
    let fn_def = symbol.ptr.to_node(&fn_file);
    let fn_def = ast::FnDef::cast(fn_def).unwrap();
    let mut call_info = CallInfo::new(fn_def)?;
diff --git a/crates/ra_ide_api/src/completion.rs b/crates/ra_ide_api/src/completion.rs
index 565d57c37..b1867de42 100644
--- a/crates/ra_ide_api/src/completion.rs
+++ b/crates/ra_ide_api/src/completion.rs
@@ -9,7 +9,7 @@ mod complete_path;
 mod complete_scope;
 mod complete_postfix;
-use ra_db::SyntaxDatabase;
+use ra_db::SourceDatabase;
 use crate::{
    db,
@@ -45,7 +45,7 @@ pub use crate::completion::completion_item::{CompletionItem, CompletionItemKind,
 /// identifier prefix/fuzzy match should be done higher in the stack, together
 /// with ordering of completions (currently this is done by the client).
 pub(crate) fn completions(db: &db::RootDatabase, position: FilePosition) -> Option<Completions> {
-    let original_file = db.source_file(position.file_id);
+    let original_file = db.parse(position.file_id);
    let ctx = CompletionContext::new(db, &original_file, position)?;
    let mut acc = Completions::default();
diff --git a/crates/ra_ide_api/src/db.rs b/crates/ra_ide_api/src/db.rs
index 30891aed4..3da93ec35 100644
--- a/crates/ra_ide_api/src/db.rs
+++ b/crates/ra_ide_api/src/db.rs
@@ -1,15 +1,14 @@
 use std::sync::Arc;
 use ra_db::{
-    BaseDatabase, FileId, Canceled,
+    CheckCanceled, FileId, Canceled, SourceDatabase,
-    salsa::{self, Database},
+    salsa,
 };
-use crate::{symbol_index, LineIndex};
+use crate::{LineIndex, symbol_index::{self, SymbolsDatabase}};
 #[salsa::database(
-    ra_db::FilesDatabaseStorage,
+    ra_db::SourceDatabaseStorage,
-    ra_db::SyntaxDatabaseStorage,
    LineIndexDatabaseStorage,
    symbol_index::SymbolsDatabaseStorage,
    hir::db::HirDatabaseStorage
@@ -35,12 +34,9 @@ impl Default for RootDatabase {
            runtime: salsa::Runtime::default(),
            interner: Default::default(),
        };
-        db.query_mut(ra_db::CrateGraphQuery)
+        db.set_crate_graph(Default::default());
-            .set((), Default::default());
+        db.set_local_roots(Default::default());
-        db.query_mut(ra_db::LocalRootsQuery)
+        db.set_library_roots(Default::default());
-            .set((), Default::default());
-        db.query_mut(ra_db::LibraryRootsQuery)
-            .set((), Default::default());
        db
    }
 }
@@ -54,7 +50,7 @@ impl salsa::ParallelDatabase for RootDatabase {
    }
 }
-impl BaseDatabase for RootDatabase {}
+impl CheckCanceled for RootDatabase {}
 impl AsRef<hir::HirInterner> for RootDatabase {
    fn as_ref(&self) -> &hir::HirInterner {
@@ -63,11 +59,11 @@ impl AsRef<hir::HirInterner> for RootDatabase {
 }
 #[salsa::query_group(LineIndexDatabaseStorage)]
-pub(crate) trait LineIndexDatabase: ra_db::FilesDatabase + BaseDatabase {
+pub(crate) trait LineIndexDatabase: ra_db::SourceDatabase + CheckCanceled {
    fn line_index(&self, file_id: FileId) -> Arc<LineIndex>;
 }
-fn line_index(db: &impl ra_db::FilesDatabase, file_id: FileId) -> Arc<LineIndex> {
+fn line_index(db: &impl ra_db::SourceDatabase, file_id: FileId) -> Arc<LineIndex> {
    let text = db.file_text(file_id);
    Arc::new(LineIndex::new(&*text))
 }
diff --git a/crates/ra_ide_api/src/extend_selection.rs b/crates/ra_ide_api/src/extend_selection.rs
index 718b4def5..cd2ebe471 100644
--- a/crates/ra_ide_api/src/extend_selection.rs
+++ b/crates/ra_ide_api/src/extend_selection.rs
@@ -1,4 +1,4 @@
-use ra_db::SyntaxDatabase;
+use ra_db::SourceDatabase;
 use ra_syntax::{
    SyntaxNode, AstNode, SourceFile,
    ast, algo::find_covering_node,
@@ -10,7 +10,7 @@ use crate::{
 };
 pub(crate) fn extend_selection(db: &RootDatabase, frange: FileRange) -> TextRange {
-    let source_file = db.source_file(frange.file_id);
+    let source_file = db.parse(frange.file_id);
    if let Some(range) = extend_selection_in_macro(db, &source_file, frange) {
        return range;
    }
diff --git a/crates/ra_ide_api/src/goto_definition.rs b/crates/ra_ide_api/src/goto_definition.rs
index dc0c50918..2a20c20ee 100644
--- a/crates/ra_ide_api/src/goto_definition.rs
+++ b/crates/ra_ide_api/src/goto_definition.rs
@@ -1,4 +1,4 @@
-use ra_db::{FileId, SyntaxDatabase};
+use ra_db::{FileId, SourceDatabase};
 use ra_syntax::{
    AstNode, ast,
    algo::find_node_at_offset,
@@ -11,7 +11,7 @@ pub(crate) fn goto_definition(
    db: &RootDatabase,
    position: FilePosition,
 ) -> Option<RangeInfo<Vec<NavigationTarget>>> {
-    let file = db.source_file(position.file_id);
+    let file = db.parse(position.file_id);
    let syntax = file.syntax();
    if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(syntax, position.offset) {
        let navs = reference_definition(db, position.file_id, name_ref).to_vec();
diff --git a/crates/ra_ide_api/src/hover.rs b/crates/ra_ide_api/src/hover.rs
index 4d4bfbc4d..ff9ae2d9c 100644
--- a/crates/ra_ide_api/src/hover.rs
+++ b/crates/ra_ide_api/src/hover.rs
@@ -1,4 +1,4 @@
-use ra_db::{SyntaxDatabase};
+use ra_db::SourceDatabase;
 use ra_syntax::{
    AstNode, SyntaxNode, TreeArc, ast,
    algo::{find_covering_node, find_node_at_offset, find_leaf_at_offset, visit::{visitor, Visitor}},
@@ -7,7 +7,7 @@ use ra_syntax::{
 use crate::{db::RootDatabase, RangeInfo, FilePosition, FileRange, NavigationTarget};
 pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeInfo<String>> {
-    let file = db.source_file(position.file_id);
+    let file = db.parse(position.file_id);
    let mut res = Vec::new();
    let mut range = None;
@@ -53,7 +53,7 @@ pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeIn
 }
 pub(crate) fn type_of(db: &RootDatabase, frange: FileRange) -> Option<String> {
-    let file = db.source_file(frange.file_id);
+    let file = db.parse(frange.file_id);
    let syntax = file.syntax();
    let leaf_node = find_covering_node(syntax, frange.range);
    // if we picked identifier, expand to pattern/expression
@@ -88,7 +88,7 @@ fn doc_text_for(db: &RootDatabase, nav: NavigationTarget) -> Option<String> {
 impl NavigationTarget {
    fn node(&self, db: &RootDatabase) -> Option<TreeArc<SyntaxNode>> {
-        let source_file = db.source_file(self.file_id());
+        let source_file = db.parse(self.file_id());
        let source_file = source_file.syntax();
        let node = source_file
            .descendants()
diff --git a/crates/ra_ide_api/src/imp.rs b/crates/ra_ide_api/src/imp.rs
index bd9e3f1e3..399433a01 100644
--- a/crates/ra_ide_api/src/imp.rs
+++ b/crates/ra_ide_api/src/imp.rs
@@ -4,7 +4,7 @@ use hir::{
    self, Problem, source_binder
 };
 use ra_db::{
-    FilesDatabase, SourceRoot, SourceRootId, SyntaxDatabase,
+    SourceDatabase, SourceRoot, SourceRootId,
    salsa::{Database, SweepStrategy},
 };
 use ra_ide_api_light::{self, assists, LocalEdit, Severity};
@@ -76,9 +76,9 @@ impl db::RootDatabase {
    /// syntax trees. However, if we actually do that, everything is recomputed
    /// for some reason. Needs investigation.
    pub(crate) fn collect_garbage(&mut self) {
-        self.query(ra_db::SourceFileQuery)
+        self.query(ra_db::ParseQuery)
            .sweep(SweepStrategy::default().discard_values());
-        self.query(hir::db::HirSourceFileQuery)
+        self.query(hir::db::HirParseQuery)
            .sweep(SweepStrategy::default().discard_values());
        self.query(hir::db::FileItemsQuery)
            .sweep(SweepStrategy::default().discard_values());
@@ -102,7 +102,7 @@ impl db::RootDatabase {
    }
    pub(crate) fn find_all_refs(&self, position: FilePosition) -> Vec<(FileId, TextRange)> {
-        let file = self.source_file(position.file_id);
+        let file = self.parse(position.file_id);
        // Find the binding associated with the offset
        let (binding, descr) = match find_binding(self, &file, position) {
            None => return Vec::new(),
@@ -150,7 +150,7 @@ impl db::RootDatabase {
    }
    pub(crate) fn diagnostics(&self, file_id: FileId) -> Vec<Diagnostic> {
-        let syntax = self.source_file(file_id);
+        let syntax = self.parse(file_id);
        let mut res = ra_ide_api_light::diagnostics(&syntax)
            .into_iter()
@@ -214,7 +214,7 @@ impl db::RootDatabase {
    }
    pub(crate) fn assists(&self, frange: FileRange) -> Vec<SourceChange> {
-        let file = self.source_file(frange.file_id);
+        let file = self.parse(frange.file_id);
        assists::assists(&file, frange.range)
            .into_iter()
            .map(|local_edit| SourceChange::from_local_edit(frange.file_id, local_edit))
diff --git a/crates/ra_ide_api/src/lib.rs b/crates/ra_ide_api/src/lib.rs
index ffd026b04..43c8bea71 100644
--- a/crates/ra_ide_api/src/lib.rs
+++ b/crates/ra_ide_api/src/lib.rs
@@ -34,7 +34,7 @@ use std::{fmt, sync::Arc};
 use ra_syntax::{SourceFile, TreeArc, TextRange, TextUnit};
 use ra_text_edit::TextEdit;
 use ra_db::{
-    SyntaxDatabase, FilesDatabase, BaseDatabase,
+    SourceDatabase, CheckCanceled,
    salsa::{self, ParallelDatabase},
 };
 use rayon::prelude::*;
@@ -313,7 +313,7 @@ impl Analysis {
    /// Gets the syntax tree of the file.
    pub fn parse(&self, file_id: FileId) -> TreeArc<SourceFile> {
-        self.db.source_file(file_id).clone()
+        self.db.parse(file_id).clone()
    }
    /// Gets the file's `LineIndex`: data structure to convert between absolute
@@ -330,21 +330,21 @@ impl Analysis {
    /// Returns position of the mathcing brace (all types of braces are
    /// supported).
    pub fn matching_brace(&self, position: FilePosition) -> Option<TextUnit> {
-        let file = self.db.source_file(position.file_id);
+        let file = self.db.parse(position.file_id);
        ra_ide_api_light::matching_brace(&file, position.offset)
    }
    /// Returns a syntax tree represented as `String`, for debug purposes.
    // FIXME: use a better name here.
    pub fn syntax_tree(&self, file_id: FileId) -> String {
-        let file = self.db.source_file(file_id);
+        let file = self.db.parse(file_id);
        ra_ide_api_light::syntax_tree(&file)
    }
    /// Returns an edit to remove all newlines in the range, cleaning up minor
    /// stuff like trailing commas.
    pub fn join_lines(&self, frange: FileRange) -> SourceChange {
-        let file = self.db.source_file(frange.file_id);
+        let file = self.db.parse(frange.file_id);
        SourceChange::from_local_edit(
            frange.file_id,
            ra_ide_api_light::join_lines(&file, frange.range),
@@ -354,7 +354,7 @@ impl Analysis {
    /// Returns an edit which should be applied when opening a new line, fixing
    /// up minor stuff like continuing the comment.
    pub fn on_enter(&self, position: FilePosition) -> Option<SourceChange> {
-        let file = self.db.source_file(position.file_id);
+        let file = self.db.parse(position.file_id);
        let edit = ra_ide_api_light::on_enter(&file, position.offset)?;
        Some(SourceChange::from_local_edit(position.file_id, edit))
    }
@@ -363,14 +363,14 @@ impl Analysis {
    /// this works when adding `let =`.
    // FIXME: use a snippet completion instead of this hack here.
    pub fn on_eq_typed(&self, position: FilePosition) -> Option<SourceChange> {
-        let file = self.db.source_file(position.file_id);
+        let file = self.db.parse(position.file_id);
        let edit = ra_ide_api_light::on_eq_typed(&file, position.offset)?;
        Some(SourceChange::from_local_edit(position.file_id, edit))
    }
    /// Returns an edit which should be applied when a dot ('.') is typed on a blank line, indenting the line appropriately.
    pub fn on_dot_typed(&self, position: FilePosition) -> Option<SourceChange> {
-        let file = self.db.source_file(position.file_id);
+        let file = self.db.parse(position.file_id);
        let edit = ra_ide_api_light::on_dot_typed(&file, position.offset)?;
        Some(SourceChange::from_local_edit(position.file_id, edit))
    }
@@ -378,13 +378,13 @@ impl Analysis {
    /// Returns a tree representation of symbols in the file. Useful to draw a
    /// file outline.
    pub fn file_structure(&self, file_id: FileId) -> Vec<StructureNode> {
-        let file = self.db.source_file(file_id);
+        let file = self.db.parse(file_id);
        ra_ide_api_light::file_structure(&file)
    }
    /// Returns the set of folding ranges.
    pub fn folding_ranges(&self, file_id: FileId) -> Vec<Fold> {
-        let file = self.db.source_file(file_id);
+        let file = self.db.parse(file_id);
        ra_ide_api_light::folding_ranges(&file)
    }
diff --git a/crates/ra_ide_api/src/rename.rs b/crates/ra_ide_api/src/rename.rs
index 5b767addd..db5ccf969 100644
--- a/crates/ra_ide_api/src/rename.rs
+++ b/crates/ra_ide_api/src/rename.rs
@@ -17,7 +17,7 @@ use crate::{
    SourceChange,
    SourceFileEdit,
 };
-use ra_db::{FilesDatabase, SyntaxDatabase};
+use ra_db::SourceDatabase;
 use relative_path::RelativePath;
 pub(crate) fn rename(
@@ -25,7 +25,7 @@ pub(crate) fn rename(
    position: FilePosition,
    new_name: &str,
 ) -> Option<SourceChange> {
-    let source_file = db.source_file(position.file_id);
+    let source_file = db.parse(position.file_id);
    let syntax = source_file.syntax();
    if let Some((ast_name, ast_module)) = find_name_and_module_at_offset(syntax, position) {
diff --git a/crates/ra_ide_api/src/runnables.rs b/crates/ra_ide_api/src/runnables.rs
index 0f9f8deb3..dc8c40ea6 100644
--- a/crates/ra_ide_api/src/runnables.rs
+++ b/crates/ra_ide_api/src/runnables.rs
@@ -3,7 +3,7 @@ use ra_syntax::{
    TextRange, SyntaxNode,
    ast::{self, AstNode, NameOwner, ModuleItemOwner},
 };
-use ra_db::SyntaxDatabase;
+use ra_db::SourceDatabase;
 use crate::{db::RootDatabase, FileId};
@@ -22,7 +22,7 @@ pub enum RunnableKind {
 }
 pub(crate) fn runnables(db: &RootDatabase, file_id: FileId) -> Vec<Runnable> {
-    let source_file = db.source_file(file_id);
+    let source_file = db.parse(file_id);
    source_file
        .syntax()
        .descendants()
diff --git a/crates/ra_ide_api/src/status.rs b/crates/ra_ide_api/src/status.rs
index 59159df98..e11eed223 100644
--- a/crates/ra_ide_api/src/status.rs
+++ b/crates/ra_ide_api/src/status.rs
@@ -6,7 +6,7 @@ use std::{
 use ra_syntax::{AstNode, TreeArc, SourceFile};
 use ra_db::{
-    SourceFileQuery, FileTextQuery, SourceRootId,
+    ParseQuery, FileTextQuery, SourceRootId,
    salsa::{Database, debug::{DebugQueryTable, TableEntry}},
 };
@@ -17,7 +17,7 @@ use crate::{
 pub(crate) fn status(db: &RootDatabase) -> String {
    let files_stats = db.query(FileTextQuery).entries::<FilesStats>();
-    let syntax_tree_stats = db.query(SourceFileQuery).entries::<SyntaxTreeStats>();
+    let syntax_tree_stats = db.query(ParseQuery).entries::<SyntaxTreeStats>();
    let symbols_stats = db
        .query(LibrarySymbolsQuery)
        .entries::<LibrarySymbolsStats>();
diff --git a/crates/ra_ide_api/src/symbol_index.rs b/crates/ra_ide_api/src/symbol_index.rs
index e073a349e..72c93f530 100644
--- a/crates/ra_ide_api/src/symbol_index.rs
+++ b/crates/ra_ide_api/src/symbol_index.rs
@@ -34,7 +34,7 @@ use ra_syntax::{
    ast::{self, NameOwner},
 };
 use ra_db::{
-    SourceRootId, FilesDatabase,
+    SourceRootId, SourceDatabase,
    salsa::{self, ParallelDatabase},
 };
 use rayon::prelude::*;
@@ -49,11 +49,19 @@ pub(crate) trait SymbolsDatabase: hir::db::HirDatabase {
    fn file_symbols(&self, file_id: FileId) -> Arc<SymbolIndex>;
    #[salsa::input]
    fn library_symbols(&self, id: SourceRootId) -> Arc<SymbolIndex>;
+    /// The set of "local" (that is, from the current workspace) roots.
+    /// Files in local roots are assumed to change frequently.
+    #[salsa::input]
+    fn local_roots(&self) -> Arc<Vec<SourceRootId>>;
+    /// The set of roots for crates.io libraries.
+    /// Files in libraries are assumed to never change.
+    #[salsa::input]
+    fn library_roots(&self) -> Arc<Vec<SourceRootId>>;
 }
 fn file_symbols(db: &impl SymbolsDatabase, file_id: FileId) -> Arc<SymbolIndex> {
    db.check_canceled();
-    let source_file = db.source_file(file_id);
+    let source_file = db.parse(file_id);
    let mut symbols = source_file
        .syntax()
        .descendants()
diff --git a/crates/ra_ide_api/src/syntax_highlighting.rs b/crates/ra_ide_api/src/syntax_highlighting.rs
index a4d3ad005..26bde495b 100644
--- a/crates/ra_ide_api/src/syntax_highlighting.rs
+++ b/crates/ra_ide_api/src/syntax_highlighting.rs
@@ -1,5 +1,5 @@
 use ra_syntax::{ast, AstNode,};
-use ra_db::SyntaxDatabase;
+use ra_db::SourceDatabase;
 use crate::{
    FileId, HighlightedRange,
@@ -7,7 +7,7 @@ use crate::{
 };
 pub(crate) fn highlight(db: &RootDatabase, file_id: FileId) -> Vec<HighlightedRange> {
-    let source_file = db.source_file(file_id);
+    let source_file = db.parse(file_id);
    let mut res = ra_ide_api_light::highlight(source_file.syntax());
    for macro_call in source_file
        .syntax()
diff --git a/crates/ra_ide_api_light/src/snapshots/tests__file_structure.snap b/crates/ra_ide_api_light/src/snapshots/tests__file_structure.snap
index b96398950..270f75a56 100644
--- a/crates/ra_ide_api_light/src/snapshots/tests__file_structure.snap
+++ b/crates/ra_ide_api_light/src/snapshots/tests__file_structure.snap
@@ -1,8 +1,8 @@
 ---
-created: "2019-01-24T18:04:00.090162+00:00"
+created: "2019-01-26T07:11:02.463391362+00:00"
-creator: insta@0.4.0
+creator: insta@0.5.2
 expression: structure
-source: "crates\\ra_ide_api_light\\src\\structure.rs"
+source: crates/ra_ide_api_light/src/structure.rs
 ---
 [
    StructureNode {
@@ -78,6 +78,26 @@ source: "crates\\ra_ide_api_light\\src\\structure.rs"
        detail: None
    },
    StructureNode {
+        parent: Some(
+            6
+        ),
+        label: "X",
+        navigation_range: [169; 170),
+        node_range: [169; 170),
+        kind: ENUM_VARIANT,
+        detail: None
+    },
+    StructureNode {
+        parent: Some(
+            6
+        ),
+        label: "Y",
+        navigation_range: [172; 173),
+        node_range: [172; 178),
+        kind: ENUM_VARIANT,
+        detail: None
+    },
+    StructureNode {
        parent: None,
        label: "T",
        navigation_range: [186; 187),
diff --git a/crates/ra_ide_api_light/src/structure.rs b/crates/ra_ide_api_light/src/structure.rs
index e3713c217..4e080ed03 100644
--- a/crates/ra_ide_api_light/src/structure.rs
+++ b/crates/ra_ide_api_light/src/structure.rs
@@ -103,6 +103,7 @@ fn structure_node(node: &SyntaxNode) -> Option<StructureNode> {
        .visit(decl::<ast::StructDef>)
        .visit(|nfd: &ast::NamedFieldDef| decl_with_type_ref(nfd, nfd.type_ref()))
        .visit(decl::<ast::EnumDef>)
+        .visit(decl::<ast::EnumVariant>)
        .visit(decl::<ast::TraitDef>)
        .visit(decl::<ast::Module>)
        .visit(|td: &ast::TypeDef| decl_with_type_ref(td, td.type_ref()))
diff --git a/crates/ra_syntax/src/grammar/types.rs b/crates/ra_syntax/src/grammar/types.rs
index 21d89d83b..adc189a29 100644
--- a/crates/ra_syntax/src/grammar/types.rs
+++ b/crates/ra_syntax/src/grammar/types.rs
@@ -29,7 +29,7 @@ fn type_with_bounds_cond(p: &mut Parser, allow_bounds: bool) {
        DYN_KW => dyn_trait_type(p),
        // Some path types are not allowed to have bounds (no plus)
        L_ANGLE => path_type_(p, allow_bounds),
-        _ if paths::is_path_start(p) => path_type_(p, allow_bounds),
+        _ if paths::is_path_start(p) => path_or_macro_type_(p, allow_bounds),
        _ => {
            p.err_recover("expected type", TYPE_RECOVERY_SET);
        }
@@ -243,6 +243,28 @@ pub(super) fn path_type(p: &mut Parser) {
    path_type_(p, true)
 }
+// test macro_call_type
+// type A = foo!();
+// type B = crate::foo!();
+fn path_or_macro_type_(p: &mut Parser, allow_bounds: bool) {
+    assert!(paths::is_path_start(p) || p.at(L_ANGLE));
+    let m = p.start();
+    paths::type_path(p);
+    let kind = if p.at(EXCL) {
+        items::macro_call_after_excl(p);
+        MACRO_CALL
+    } else {
+        PATH_TYPE
+    };
+    if allow_bounds && p.eat(PLUS) {
+        type_params::bounds_without_colon(p);
+    }
+    m.complete(p, kind);
+}
 pub(super) fn path_type_(p: &mut Parser, allow_bounds: bool) {
    assert!(paths::is_path_start(p) || p.at(L_ANGLE));
    let m = p.start();
diff --git a/crates/ra_syntax/tests/data/parser/inline/ok/0117_macro_call_type.rs b/crates/ra_syntax/tests/data/parser/inline/ok/0117_macro_call_type.rs
new file mode 100644
index 000000000..edb470c89
--- /dev/null
+++ b/crates/ra_syntax/tests/data/parser/inline/ok/0117_macro_call_type.rs
@@ -0,0 +1,2 @@
+type A = foo!();
+type B = crate::foo!();
diff --git a/crates/ra_syntax/tests/data/parser/inline/ok/0117_macro_call_type.txt b/crates/ra_syntax/tests/data/parser/inline/ok/0117_macro_call_type.txt
new file mode 100644
index 000000000..b2d95451c
--- /dev/null
+++ b/crates/ra_syntax/tests/data/parser/inline/ok/0117_macro_call_type.txt
@@ -0,0 +1,43 @@
+SOURCE_FILE@[0; 41)
+  TYPE_DEF@[0; 16)
+    TYPE_KW@[0; 4)
+    WHITESPACE@[4; 5)
+    NAME@[5; 6)
+      IDENT@[5; 6) "A"
+    WHITESPACE@[6; 7)
+    EQ@[7; 8)
+    WHITESPACE@[8; 9)
+    MACRO_CALL@[9; 15)
+      PATH@[9; 12)
+        PATH_SEGMENT@[9; 12)
+          NAME_REF@[9; 12)
+            IDENT@[9; 12) "foo"
+      EXCL@[12; 13)
+      TOKEN_TREE@[13; 15)
+        L_PAREN@[13; 14)
+        R_PAREN@[14; 15)
+    SEMI@[15; 16)
+  WHITESPACE@[16; 17)
+  TYPE_DEF@[17; 40)
+    TYPE_KW@[17; 21)
+    WHITESPACE@[21; 22)
+    NAME@[22; 23)
+      IDENT@[22; 23) "B"
+    WHITESPACE@[23; 24)
+    EQ@[24; 25)
+    WHITESPACE@[25; 26)
+    MACRO_CALL@[26; 39)
+      PATH@[26; 36)
+        PATH@[26; 31)
+          PATH_SEGMENT@[26; 31)
+            CRATE_KW@[26; 31)
+        COLONCOLON@[31; 33)
+        PATH_SEGMENT@[33; 36)
+          NAME_REF@[33; 36)
+            IDENT@[33; 36) "foo"
+      EXCL@[36; 37)
+      TOKEN_TREE@[37; 39)
+        L_PAREN@[37; 38)
+        R_PAREN@[38; 39)
+    SEMI@[39; 40)
+  WHITESPACE@[40; 41)
diff --git a/crates/ra_vfs/Cargo.toml b/crates/ra_vfs/Cargo.toml
index e637063c9..383381d2a 100644
--- a/crates/ra_vfs/Cargo.toml
+++ b/crates/ra_vfs/Cargo.toml
@@ -10,9 +10,13 @@ relative-path = "0.4.0"
 rustc-hash = "1.0"
 crossbeam-channel = "0.3.5"
 log = "0.4.6"
+notify = "4.0.7"
+drop_bomb = "0.1.0"
+parking_lot = "0.7.0"
 thread_worker = { path = "../thread_worker" }
 ra_arena = { path = "../ra_arena" }
 [dev-dependencies]
 tempfile = "3"
+flexi_logger = "0.10.0"
diff --git a/crates/ra_vfs/src/io.rs b/crates/ra_vfs/src/io.rs
index 80328ad18..7ca1e9835 100644
--- a/crates/ra_vfs/src/io.rs
+++ b/crates/ra_vfs/src/io.rs
@@ -1,55 +1,109 @@
-use std::{
+use std::{fs, sync::Arc, thread};
-    fmt,
-    fs,
-    path::{Path, PathBuf},
-};
-use walkdir::{DirEntry, WalkDir};
+use crossbeam_channel::{Receiver, Sender};
-use thread_worker::{WorkerHandle};
 use relative_path::RelativePathBuf;
+use thread_worker::WorkerHandle;
+use walkdir::WalkDir;
-use crate::{VfsRoot, has_rs_extension};
+mod watcher;
+use watcher::Watcher;
-pub(crate) struct Task {
+use crate::{RootFilter, Roots, VfsRoot};
-    pub(crate) root: VfsRoot,
-    pub(crate) path: PathBuf,
+pub(crate) enum Task {
-    pub(crate) filter: Box<Fn(&DirEntry) -> bool + Send>,
+    AddRoot {
+        root: VfsRoot,
+        filter: Arc<RootFilter>,
+    },
 }
-pub struct TaskResult {
+#[derive(Debug)]
-    pub(crate) root: VfsRoot,
+pub enum TaskResult {
-    pub(crate) files: Vec<(RelativePathBuf, String)>,
+    BulkLoadRoot {
+        root: VfsRoot,
+        files: Vec<(RelativePathBuf, String)>,
+    },
+    AddSingleFile {
+        root: VfsRoot,
+        path: RelativePathBuf,
+        text: String,
+    },
+    ChangeSingleFile {
+        root: VfsRoot,
+        path: RelativePathBuf,
+        text: String,
+    },
+    RemoveSingleFile {
+        root: VfsRoot,
+        path: RelativePathBuf,
+    },
 }
-impl fmt::Debug for TaskResult {
+pub(crate) struct Worker {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    worker: thread_worker::Worker<Task, TaskResult>,
-        f.write_str("TaskResult { ... }")
+    worker_handle: WorkerHandle,
-    }
 }
-pub(crate) type Worker = thread_worker::Worker<Task, TaskResult>;
+impl Worker {
+    pub(crate) fn start(roots: Arc<Roots>) -> Worker {
+        let (worker, worker_handle) =
+            thread_worker::spawn("vfs", 128, move |input_receiver, output_sender| {
+                let mut watcher = match Watcher::start(roots, output_sender.clone()) {
+                    Ok(w) => Some(w),
+                    Err(e) => {
+                        log::error!("could not start watcher: {}", e);
+                        None
+                    }
+                };
+                let res = input_receiver
+                    .into_iter()
+                    .filter_map(|t| handle_task(t, &mut watcher))
+                    .try_for_each(|it| output_sender.send(it));
+                if let Some(watcher) = watcher {
+                    let _ = watcher.shutdown();
+                }
+                res.unwrap()
+            });
+        Worker {
+            worker,
+            worker_handle,
+        }
+    }
+    pub(crate) fn sender(&self) -> &Sender<Task> {
+        &self.worker.inp
+    }
+    pub(crate) fn receiver(&self) -> &Receiver<TaskResult> {
+        &self.worker.out
+    }
-pub(crate) fn start() -> (Worker, WorkerHandle) {
+    pub(crate) fn shutdown(self) -> thread::Result<()> {
-    thread_worker::spawn("vfs", 128, |input_receiver, output_sender| {
+        let _ = self.worker.shutdown();
-        input_receiver
+        self.worker_handle.shutdown()
-            .into_iter()
+    }
-            .map(handle_task)
-            .try_for_each(|it| output_sender.send(it))
-            .unwrap()
-    })
 }
-fn handle_task(task: Task) -> TaskResult {
+fn handle_task(task: Task, watcher: &mut Option<Watcher>) -> Option<TaskResult> {
-    let Task { root, path, filter } = task;
+    match task {
-    log::debug!("loading {} ...", path.as_path().display());
+        Task::AddRoot { root, filter } => {
-    let files = load_root(path.as_path(), &*filter);
+            if let Some(watcher) = watcher {
-    log::debug!("... loaded {}", path.as_path().display());
+                watcher.watch_root(&filter)
-    TaskResult { root, files }
+            }
+            log::debug!("loading {} ...", filter.root.as_path().display());
+            let files = load_root(filter.as_ref());
+            log::debug!("... loaded {}", filter.root.as_path().display());
+            Some(TaskResult::BulkLoadRoot { root, files })
+        }
+    }
 }
-fn load_root(root: &Path, filter: &dyn Fn(&DirEntry) -> bool) -> Vec<(RelativePathBuf, String)> {
+fn load_root(filter: &RootFilter) -> Vec<(RelativePathBuf, String)> {
    let mut res = Vec::new();
-    for entry in WalkDir::new(root).into_iter().filter_entry(filter) {
+    for entry in WalkDir::new(&filter.root)
+        .into_iter()
+        .filter_entry(filter.entry_filter())
+    {
        let entry = match entry {
            Ok(entry) => entry,
            Err(e) => {
@@ -61,9 +115,6 @@ fn load_root(root: &Path, filter: &dyn Fn(&DirEntry) -> bool) -> Vec<(RelativePa
            continue;
        }
        let path = entry.path();
-        if !has_rs_extension(path) {
-            continue;
-        }
        let text = match fs::read_to_string(path) {
            Ok(text) => text,
            Err(e) => {
@@ -71,7 +122,7 @@ fn load_root(root: &Path, filter: &dyn Fn(&DirEntry) -> bool) -> Vec<(RelativePa
                continue;
            }
        };
-        let path = RelativePathBuf::from_path(path.strip_prefix(root).unwrap()).unwrap();
+        let path = RelativePathBuf::from_path(path.strip_prefix(&filter.root).unwrap()).unwrap();
        res.push((path.to_owned(), text))
    }
    res
diff --git a/crates/ra_vfs/src/io/watcher.rs b/crates/ra_vfs/src/io/watcher.rs
new file mode 100644
index 000000000..ff6775f59
--- /dev/null
+++ b/crates/ra_vfs/src/io/watcher.rs
@@ -0,0 +1,200 @@
+use crate::{io, RootFilter, Roots, VfsRoot};
+use crossbeam_channel::Sender;
+use drop_bomb::DropBomb;
+use notify::{DebouncedEvent, RecommendedWatcher, RecursiveMode, Watcher as NotifyWatcher};
+use parking_lot::Mutex;
+use std::{
+    fs,
+    path::{Path, PathBuf},
+    sync::{mpsc, Arc},
+    thread,
+    time::Duration,
+};
+use walkdir::WalkDir;
+#[derive(Debug)]
+enum ChangeKind {
+    Create,
+    Write,
+    Remove,
+}
+const WATCHER_DELAY: Duration = Duration::from_millis(250);
+pub(crate) struct Watcher {
+    thread: thread::JoinHandle<()>,
+    bomb: DropBomb,
+    watcher: Arc<Mutex<Option<RecommendedWatcher>>>,
+}
+impl Watcher {
+    pub(crate) fn start(
+        roots: Arc<Roots>,
+        output_sender: Sender<io::TaskResult>,
+    ) -> Result<Watcher, Box<std::error::Error>> {
+        let (input_sender, input_receiver) = mpsc::channel();
+        let watcher = Arc::new(Mutex::new(Some(notify::watcher(
+            input_sender,
+            WATCHER_DELAY,
+        )?)));
+        let sender = output_sender.clone();
+        let watcher_clone = watcher.clone();
+        let thread = thread::spawn(move || {
+            let worker = WatcherWorker {
+                roots,
+                watcher: watcher_clone,
+                sender,
+            };
+            input_receiver
+                .into_iter()
+                // forward relevant events only
+                .try_for_each(|change| worker.handle_debounced_event(change))
+                .unwrap()
+        });
+        Ok(Watcher {
+            thread,
+            watcher,
+            bomb: DropBomb::new(format!("Watcher was not shutdown")),
+        })
+    }
+    pub fn watch_root(&mut self, filter: &RootFilter) {
+        for res in WalkDir::new(&filter.root)
+            .into_iter()
+            .filter_entry(filter.entry_filter())
+        {
+            match res {
+                Ok(entry) => {
+                    if entry.file_type().is_dir() {
+                        watch_one(self.watcher.as_ref(), entry.path());
+                    }
+                }
+                Err(e) => log::warn!("watcher error: {}", e),
+            }
+        }
+    }
+    pub fn shutdown(mut self) -> thread::Result<()> {
+        self.bomb.defuse();
+        drop(self.watcher.lock().take());
+        let res = self.thread.join();
+        match &res {
+            Ok(()) => log::info!("... Watcher terminated with ok"),
+            Err(_) => log::error!("... Watcher terminated with err"),
+        }
+        res
+    }
+}
+struct WatcherWorker {
+    watcher: Arc<Mutex<Option<RecommendedWatcher>>>,
+    roots: Arc<Roots>,
+    sender: Sender<io::TaskResult>,
+}
+impl WatcherWorker {
+    fn handle_debounced_event(&self, ev: DebouncedEvent) -> Result<(), Box<std::error::Error>> {
+        match ev {
+            DebouncedEvent::NoticeWrite(_)
+            | DebouncedEvent::NoticeRemove(_)
+            | DebouncedEvent::Chmod(_) => {
+                // ignore
+            }
+            DebouncedEvent::Rescan => {
+                // TODO rescan all roots
+            }
+            DebouncedEvent::Create(path) => {
+                self.handle_change(path, ChangeKind::Create);
+            }
+            DebouncedEvent::Write(path) => {
+                self.handle_change(path, ChangeKind::Write);
+            }
+            DebouncedEvent::Remove(path) => {
+                self.handle_change(path, ChangeKind::Remove);
+            }
+            DebouncedEvent::Rename(src, dst) => {
+                self.handle_change(src, ChangeKind::Remove);
+                self.handle_change(dst, ChangeKind::Create);
+            }
+            DebouncedEvent::Error(err, path) => {
+                // TODO should we reload the file contents?
+                log::warn!("watcher error \"{}\", {:?}", err, path);
+            }
+        }
+        Ok(())
+    }
+    fn handle_change(&self, path: PathBuf, kind: ChangeKind) {
+        if let Err(e) = self.try_handle_change(path, kind) {
+            log::warn!("watcher error: {}", e)
+        }
+    }
+    fn try_handle_change(
+        &self,
+        path: PathBuf,
+        kind: ChangeKind,
+    ) -> Result<(), Box<std::error::Error>> {
+        let (root, rel_path) = match self.roots.find(&path) {
+            Some(x) => x,
+            None => return Ok(()),
+        };
+        match kind {
+            ChangeKind::Create => {
+                if path.is_dir() {
+                    self.watch_recursive(&path, root);
+                } else {
+                    let text = fs::read_to_string(&path)?;
+                    self.sender.send(io::TaskResult::AddSingleFile {
+                        root,
+                        path: rel_path,
+                        text,
+                    })?
+                }
+            }
+            ChangeKind::Write => {
+                let text = fs::read_to_string(&path)?;
+                self.sender.send(io::TaskResult::ChangeSingleFile {
+                    root,
+                    path: rel_path,
+                    text,
+                })?
+            }
+            ChangeKind::Remove => self.sender.send(io::TaskResult::RemoveSingleFile {
+                root,
+                path: rel_path,
+            })?,
+        }
+        Ok(())
+    }
+    fn watch_recursive(&self, dir: &Path, root: VfsRoot) {
+        let filter = &self.roots[root];
+        for res in WalkDir::new(dir)
+            .into_iter()
+            .filter_entry(filter.entry_filter())
+        {
+            match res {
+                Ok(entry) => {
+                    if entry.file_type().is_dir() {
+                        watch_one(self.watcher.as_ref(), entry.path());
+                    } else {
+                        // emit only for files otherwise we will cause watch_recursive to be called again with a dir that we are already watching
+                        // emit as create because we haven't seen it yet
+                        self.handle_change(entry.path().to_path_buf(), ChangeKind::Create);
+                    }
+                }
+                Err(e) => log::warn!("watcher error: {}", e),
+            }
+        }
+    }
+}
+fn watch_one(watcher: &Mutex<Option<RecommendedWatcher>>, dir: &Path) {
+    if let Some(watcher) = watcher.lock().as_mut() {
+        match watcher.watch(dir, RecursiveMode::NonRecursive) {
+            Ok(()) => log::debug!("watching \"{}\"", dir.display()),
+            Err(e) => log::warn!("could not watch \"{}\": {}", dir.display(), e),
+        }
+    }
+}
diff --git a/crates/ra_vfs/src/lib.rs b/crates/ra_vfs/src/lib.rs
index cdea18d73..70a13f765 100644
--- a/crates/ra_vfs/src/lib.rs
+++ b/crates/ra_vfs/src/lib.rs
@@ -16,52 +16,77 @@
 mod io;
 use std::{
-    fmt,
-    mem,
-    thread,
    cmp::Reverse,
+    fmt, fs, mem,
+    ops::{Deref, DerefMut},
    path::{Path, PathBuf},
-    ffi::OsStr,
    sync::Arc,
-    fs,
+    thread,
 };
-use rustc_hash::{FxHashMap, FxHashSet};
-use relative_path::RelativePathBuf;
 use crossbeam_channel::Receiver;
+use ra_arena::{impl_arena_id, Arena, RawId};
+use relative_path::{Component, RelativePath, RelativePathBuf};
+use rustc_hash::{FxHashMap, FxHashSet};
 use walkdir::DirEntry;
-use thread_worker::WorkerHandle;
-use ra_arena::{Arena, RawId, impl_arena_id};
 pub use crate::io::TaskResult as VfsTask;
+use io::{TaskResult, Worker};
 /// `RootFilter` is a predicate that checks if a file can belong to a root. If
 /// several filters match a file (nested dirs), the most nested one wins.
-struct RootFilter {
+pub(crate) struct RootFilter {
    root: PathBuf,
-    file_filter: fn(&Path) -> bool,
+    filter: fn(&Path, &RelativePath) -> bool,
+    excluded_dirs: Vec<PathBuf>,
 }
 impl RootFilter {
-    fn new(root: PathBuf) -> RootFilter {
+    fn new(root: PathBuf, excluded_dirs: Vec<PathBuf>) -> RootFilter {
        RootFilter {
            root,
-            file_filter: has_rs_extension,
+            filter: default_filter,
+            excluded_dirs,
        }
    }
    /// Check if this root can contain `path`. NB: even if this returns
    /// true, the `path` might actually be conained in some nested root.
-    fn can_contain(&self, path: &Path) -> Option<RelativePathBuf> {
+    pub(crate) fn can_contain(&self, path: &Path) -> Option<RelativePathBuf> {
-        if !(self.file_filter)(path) {
+        let rel_path = path.strip_prefix(&self.root).ok()?;
+        let rel_path = RelativePathBuf::from_path(rel_path).ok()?;
+        if !(self.filter)(path, rel_path.as_relative_path()) {
            return None;
        }
-        let path = path.strip_prefix(&self.root).ok()?;
+        Some(rel_path)
-        RelativePathBuf::from_path(path).ok()
+    }
+    pub(crate) fn entry_filter<'a>(&'a self) -> impl FnMut(&DirEntry) -> bool + 'a {
+        move |entry: &DirEntry| {
+            if entry.file_type().is_dir() && self.excluded_dirs.iter().any(|it| it == entry.path())
+            {
+                // do not walk nested roots
+                false
+            } else {
+                self.can_contain(entry.path()).is_some()
+            }
+        }
    }
 }
-fn has_rs_extension(p: &Path) -> bool {
+pub(crate) fn default_filter(path: &Path, rel_path: &RelativePath) -> bool {
-    p.extension() == Some(OsStr::new("rs"))
+    if path.is_dir() {
+        for (i, c) in rel_path.components().enumerate() {
+            if let Component::Normal(c) = c {
+                // TODO hardcoded for now
+                if (i == 0 && c == "target") || c == ".git" || c == "node_modules" {
+                    return false;
+                }
+            }
+        }
+        true
+    } else {
+        rel_path.extension() == Some("rs")
+    }
 }
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -75,16 +100,58 @@ impl_arena_id!(VfsFile);
 struct VfsFileData {
    root: VfsRoot,
    path: RelativePathBuf,
+    is_overlayed: bool,
    text: Arc<String>,
 }
+pub(crate) struct Roots {
+    roots: Arena<VfsRoot, Arc<RootFilter>>,
+}
+impl Roots {
+    pub(crate) fn new(mut paths: Vec<PathBuf>) -> Roots {
+        let mut roots = Arena::default();
+        // A hack to make nesting work.
+        paths.sort_by_key(|it| Reverse(it.as_os_str().len()));
+        for (i, path) in paths.iter().enumerate() {
+            let nested_roots = paths[..i]
+                .iter()
+                .filter(|it| it.starts_with(path))
+                .map(|it| it.clone())
+                .collect::<Vec<_>>();
+            let root_filter = Arc::new(RootFilter::new(path.clone(), nested_roots));
+            roots.alloc(root_filter.clone());
+        }
+        Roots { roots }
+    }
+    pub(crate) fn find(&self, path: &Path) -> Option<(VfsRoot, RelativePathBuf)> {
+        self.roots
+            .iter()
+            .find_map(|(root, data)| data.can_contain(path).map(|it| (root, it)))
+    }
+}
+impl Deref for Roots {
+    type Target = Arena<VfsRoot, Arc<RootFilter>>;
+    fn deref(&self) -> &Self::Target {
+        &self.roots
+    }
+}
+impl DerefMut for Roots {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.roots
+    }
+}
 pub struct Vfs {
-    roots: Arena<VfsRoot, RootFilter>,
+    roots: Arc<Roots>,
    files: Arena<VfsFile, VfsFileData>,
    root2files: FxHashMap<VfsRoot, FxHashSet<VfsFile>>,
    pending_changes: Vec<VfsChange>,
-    worker: io::Worker,
+    worker: Worker,
-    worker_handle: WorkerHandle,
 }
 impl fmt::Debug for Vfs {
@@ -94,44 +161,30 @@ impl fmt::Debug for Vfs {
 }
 impl Vfs {
-    pub fn new(mut roots: Vec<PathBuf>) -> (Vfs, Vec<VfsRoot>) {
+    pub fn new(roots: Vec<PathBuf>) -> (Vfs, Vec<VfsRoot>) {
-        let (worker, worker_handle) = io::start();
+        let roots = Arc::new(Roots::new(roots));
+        let worker = io::Worker::start(roots.clone());
-        let mut res = Vfs {
+        let mut root2files = FxHashMap::default();
-            roots: Arena::default(),
+        for (root, filter) in roots.iter() {
+            root2files.insert(root, Default::default());
+            worker
+                .sender()
+                .send(io::Task::AddRoot {
+                    root,
+                    filter: filter.clone(),
+                })
+                .unwrap();
+        }
+        let res = Vfs {
+            roots,
            files: Arena::default(),
-            root2files: FxHashMap::default(),
+            root2files,
            worker,
-            worker_handle,
            pending_changes: Vec::new(),
        };
+        let vfs_roots = res.roots.iter().map(|(id, _)| id).collect();
-        // A hack to make nesting work.
+        (res, vfs_roots)
-        roots.sort_by_key(|it| Reverse(it.as_os_str().len()));
-        for (i, path) in roots.iter().enumerate() {
-            let root = res.roots.alloc(RootFilter::new(path.clone()));
-            res.root2files.insert(root, Default::default());
-            let nested = roots[..i]
-                .iter()
-                .filter(|it| it.starts_with(path))
-                .map(|it| it.clone())
-                .collect::<Vec<_>>();
-            let filter = move |entry: &DirEntry| {
-                if entry.file_type().is_file() {
-                    has_rs_extension(entry.path())
-                } else {
-                    nested.iter().all(|it| it != entry.path())
-                }
-            };
-            let task = io::Task {
-                root,
-                path: path.clone(),
-                filter: Box::new(filter),
-            };
-            res.worker.inp.send(task).unwrap();
-        }
-        let roots = res.roots.iter().map(|(id, _)| id).collect();
-        (res, roots)
    }
    pub fn root2path(&self, root: VfsRoot) -> PathBuf {
@@ -165,7 +218,7 @@ impl Vfs {
            } else {
                let text = fs::read_to_string(path).unwrap_or_default();
                let text = Arc::new(text);
-                let file = self.add_file(root, rel_path.clone(), Arc::clone(&text));
+                let file = self.add_file(root, rel_path.clone(), Arc::clone(&text), false);
                let change = VfsChange::AddFile {
                    file,
                    text,
@@ -180,85 +233,132 @@ impl Vfs {
    }
    pub fn task_receiver(&self) -> &Receiver<io::TaskResult> {
-        &self.worker.out
+        self.worker.receiver()
    }
    pub fn handle_task(&mut self, task: io::TaskResult) {
-        let mut files = Vec::new();
+        match task {
-        // While we were scanning the root in the backgound, a file might have
+            TaskResult::BulkLoadRoot { root, files } => {
-        // been open in the editor, so we need to account for that.
+                let mut cur_files = Vec::new();
-        let exising = self.root2files[&task.root]
+                // While we were scanning the root in the backgound, a file might have
-            .iter()
+                // been open in the editor, so we need to account for that.
-            .map(|&file| (self.files[file].path.clone(), file))
+                let exising = self.root2files[&root]
-            .collect::<FxHashMap<_, _>>();
+                    .iter()
-        for (path, text) in task.files {
+                    .map(|&file| (self.files[file].path.clone(), file))
-            if let Some(&file) = exising.get(&path) {
+                    .collect::<FxHashMap<_, _>>();
-                let text = Arc::clone(&self.files[file].text);
+                for (path, text) in files {
-                files.push((file, path, text));
+                    if let Some(&file) = exising.get(&path) {
-                continue;
+                        let text = Arc::clone(&self.files[file].text);
+                        cur_files.push((file, path, text));
+                        continue;
+                    }
+                    let text = Arc::new(text);
+                    let file = self.add_file(root, path.clone(), Arc::clone(&text), false);
+                    cur_files.push((file, path, text));
+                }
+                let change = VfsChange::AddRoot {
+                    root,
+                    files: cur_files,
+                };
+                self.pending_changes.push(change);
+            }
+            TaskResult::AddSingleFile { root, path, text } => {
+                if self.find_file(root, &path).is_none() {
+                    self.do_add_file(root, path, text, false);
+                }
+            }
+            TaskResult::ChangeSingleFile { root, path, text } => {
+                if let Some(file) = self.find_file(root, &path) {
+                    self.do_change_file(file, text, false);
+                } else {
+                    self.do_add_file(root, path, text, false);
+                }
+            }
+            TaskResult::RemoveSingleFile { root, path } => {
+                if let Some(file) = self.find_file(root, &path) {
+                    self.do_remove_file(root, path, file, false);
+                }
            }
-            let text = Arc::new(text);
-            let file = self.add_file(task.root, path.clone(), Arc::clone(&text));
-            files.push((file, path, text));
        }
+    }
-        let change = VfsChange::AddRoot {
+    fn do_add_file(
-            root: task.root,
+        &mut self,
-            files,
+        root: VfsRoot,
-        };
+        path: RelativePathBuf,
-        self.pending_changes.push(change);
+        text: String,
+        is_overlay: bool,
+    ) -> Option<VfsFile> {
+        let text = Arc::new(text);
+        let file = self.add_file(root, path.clone(), text.clone(), is_overlay);
+        self.pending_changes.push(VfsChange::AddFile {
+            file,
+            root,
+            path,
+            text,
+        });
+        Some(file)
+    }
+    fn do_change_file(&mut self, file: VfsFile, text: String, is_overlay: bool) {
+        if !is_overlay && self.files[file].is_overlayed {
+            return;
+        }
+        let text = Arc::new(text);
+        self.change_file(file, text.clone(), is_overlay);
+        self.pending_changes
+            .push(VfsChange::ChangeFile { file, text });
+    }
+    fn do_remove_file(
+        &mut self,
+        root: VfsRoot,
+        path: RelativePathBuf,
+        file: VfsFile,
+        is_overlay: bool,
+    ) {
+        if !is_overlay && self.files[file].is_overlayed {
+            return;
+        }
+        self.remove_file(file);
+        self.pending_changes
+            .push(VfsChange::RemoveFile { root, path, file });
    }
    pub fn add_file_overlay(&mut self, path: &Path, text: String) -> Option<VfsFile> {
-        let mut res = None;
+        if let Some((root, rel_path, file)) = self.find_root(path) {
-        if let Some((root, path, file)) = self.find_root(path) {
+            if let Some(file) = file {
-            let text = Arc::new(text);
+                self.do_change_file(file, text, true);
-            let change = if let Some(file) = file {
+                Some(file)
-                res = Some(file);
-                self.change_file(file, Arc::clone(&text));
-                VfsChange::ChangeFile { file, text }
            } else {
-                let file = self.add_file(root, path.clone(), Arc::clone(&text));
+                self.do_add_file(root, rel_path, text, true)
-                res = Some(file);
+            }
-                VfsChange::AddFile {
+        } else {
-                    file,
+            None
-                    text,
-                    root,
-                    path,
-                }
-            };
-            self.pending_changes.push(change);
        }
-        res
    }
    pub fn change_file_overlay(&mut self, path: &Path, new_text: String) {
        if let Some((_root, _path, file)) = self.find_root(path) {
            let file = file.expect("can't change a file which wasn't added");
-            let text = Arc::new(new_text);
+            self.do_change_file(file, new_text, true);
-            self.change_file(file, Arc::clone(&text));
-            let change = VfsChange::ChangeFile { file, text };
-            self.pending_changes.push(change);
        }
    }
    pub fn remove_file_overlay(&mut self, path: &Path) -> Option<VfsFile> {
-        let mut res = None;
        if let Some((root, path, file)) = self.find_root(path) {
            let file = file.expect("can't remove a file which wasn't added");
-            res = Some(file);
            let full_path = path.to_path(&self.roots[root].root);
-            let change = if let Ok(text) = fs::read_to_string(&full_path) {
+            if let Ok(text) = fs::read_to_string(&full_path) {
-                let text = Arc::new(text);
+                self.do_change_file(file, text, true);
-                self.change_file(file, Arc::clone(&text));
-                VfsChange::ChangeFile { file, text }
            } else {
-                self.remove_file(file);
+                self.do_remove_file(root, path, file, true);
-                VfsChange::RemoveFile { root, file, path }
+            }
-            };
+            Some(file)
-            self.pending_changes.push(change);
+        } else {
+            None
        }
-        res
    }
    pub fn commit_changes(&mut self) -> Vec<VfsChange> {
@@ -267,19 +367,31 @@ impl Vfs {
    /// Sutdown the VFS and terminate the background watching thread.
    pub fn shutdown(self) -> thread::Result<()> {
-        let _ = self.worker.shutdown();
+        self.worker.shutdown()
-        self.worker_handle.shutdown()
    }
-    fn add_file(&mut self, root: VfsRoot, path: RelativePathBuf, text: Arc<String>) -> VfsFile {
+    fn add_file(
-        let data = VfsFileData { root, path, text };
+        &mut self,
+        root: VfsRoot,
+        path: RelativePathBuf,
+        text: Arc<String>,
+        is_overlayed: bool,
+    ) -> VfsFile {
+        let data = VfsFileData {
+            root,
+            path,
+            text,
+            is_overlayed,
+        };
        let file = self.files.alloc(data);
        self.root2files.get_mut(&root).unwrap().insert(file);
        file
    }
-    fn change_file(&mut self, file: VfsFile, new_text: Arc<String>) {
+    fn change_file(&mut self, file: VfsFile, new_text: Arc<String>, is_overlayed: bool) {
-        self.files[file].text = new_text;
+        let mut file_data = &mut self.files[file];
+        file_data.text = new_text;
+        file_data.is_overlayed = is_overlayed;
    }
    fn remove_file(&mut self, file: VfsFile) {
@@ -292,15 +404,16 @@ impl Vfs {
    }
    fn find_root(&self, path: &Path) -> Option<(VfsRoot, RelativePathBuf, Option<VfsFile>)> {
-        let (root, path) = self
+        let (root, path) = self.roots.find(&path)?;
-            .roots
+        let file = self.find_file(root, &path);
-            .iter()
+        Some((root, path, file))
-            .find_map(|(root, data)| data.can_contain(path).map(|it| (root, it)))?;
+    }
-        let file = self.root2files[&root]
+    fn find_file(&self, root: VfsRoot, path: &RelativePath) -> Option<VfsFile> {
+        self.root2files[&root]
            .iter()
            .map(|&it| it)
-            .find(|&file| self.files[file].path == path);
+            .find(|&file| self.files[file].path == path)
-        Some((root, path, file))
    }
 }
diff --git a/crates/ra_vfs/tests/vfs.rs b/crates/ra_vfs/tests/vfs.rs
index f56fc4603..545e1dbdd 100644
--- a/crates/ra_vfs/tests/vfs.rs
+++ b/crates/ra_vfs/tests/vfs.rs
@@ -1,24 +1,47 @@
-use std::{
+use std::{collections::HashSet, fs, time::Duration};
-    fs,
-    collections::HashSet,
-};
+// use flexi_logger::Logger;
+use crossbeam_channel::RecvTimeoutError;
+use ra_vfs::{Vfs, VfsChange};
 use tempfile::tempdir;
-use ra_vfs::{Vfs, VfsChange};
+fn process_tasks(vfs: &mut Vfs, num_tasks: u32) {
+    for _ in 0..num_tasks {
+        let task = vfs
+            .task_receiver()
+            .recv_timeout(Duration::from_secs(3))
+            .unwrap();
+        log::debug!("{:?}", task);
+        vfs.handle_task(task);
+    }
+}
+macro_rules! assert_match {
+    ($x:expr, $pat:pat) => {
+        assert_match!($x, $pat, ())
+    };
+    ($x:expr, $pat:pat, $assert:expr) => {
+        match $x {
+            $pat => $assert,
+            x => assert!(false, "Expected {}, got {:?}", stringify!($pat), x),
+        };
+    };
+}
 #[test]
 fn test_vfs_works() -> std::io::Result<()> {
+    // Logger::with_str("vfs=debug,ra_vfs=debug").start().unwrap();
    let files = [
        ("a/foo.rs", "hello"),
        ("a/bar.rs", "world"),
        ("a/b/baz.rs", "nested hello"),
    ];
-    let dir = tempdir()?;
+    let dir = tempdir().unwrap();
    for (path, text) in files.iter() {
        let file_path = dir.path().join(path);
-        fs::create_dir_all(file_path.parent().unwrap())?;
+        fs::create_dir_all(file_path.parent().unwrap()).unwrap();
        fs::write(file_path, text)?
    }
@@ -26,10 +49,7 @@ fn test_vfs_works() -> std::io::Result<()> {
    let b_root = dir.path().join("a/b");
    let (mut vfs, _) = Vfs::new(vec![a_root, b_root]);
-    for _ in 0..2 {
+    process_tasks(&mut vfs, 2);
-        let task = vfs.task_receiver().recv().unwrap();
-        vfs.handle_task(task);
-    }
    {
        let files = vfs
            .commit_changes()
@@ -58,44 +78,114 @@ fn test_vfs_works() -> std::io::Result<()> {
        assert_eq!(files, expected_files);
    }
-    vfs.add_file_overlay(&dir.path().join("a/b/baz.rs"), "quux".to_string());
+    fs::write(&dir.path().join("a/b/baz.rs"), "quux").unwrap();
-    let change = vfs.commit_changes().pop().unwrap();
+    process_tasks(&mut vfs, 1);
-    match change {
+    assert_match!(
-        VfsChange::ChangeFile { text, .. } => assert_eq!(&*text, "quux"),
+        vfs.commit_changes().as_slice(),
-        _ => panic!("unexpected change"),
+        [VfsChange::ChangeFile { text, .. }],
-    }
+        assert_eq!(text.as_str(), "quux")
+    );
-    vfs.change_file_overlay(&dir.path().join("a/b/baz.rs"), "m".to_string());
+    vfs.add_file_overlay(&dir.path().join("a/b/baz.rs"), "m".to_string());
-    let change = vfs.commit_changes().pop().unwrap();
+    assert_match!(
-    match change {
+        vfs.commit_changes().as_slice(),
-        VfsChange::ChangeFile { text, .. } => assert_eq!(&*text, "m"),
+        [VfsChange::ChangeFile { text, .. }],
-        _ => panic!("unexpected change"),
+        assert_eq!(text.as_str(), "m")
-    }
+    );
+    // changing file on disk while overlayed doesn't generate a VfsChange
+    fs::write(&dir.path().join("a/b/baz.rs"), "corge").unwrap();
+    process_tasks(&mut vfs, 1);
+    assert_match!(vfs.commit_changes().as_slice(), []);
+    // removing overlay restores data on disk
    vfs.remove_file_overlay(&dir.path().join("a/b/baz.rs"));
-    let change = vfs.commit_changes().pop().unwrap();
+    assert_match!(
-    match change {
+        vfs.commit_changes().as_slice(),
-        VfsChange::ChangeFile { text, .. } => assert_eq!(&*text, "nested hello"),
+        [VfsChange::ChangeFile { text, .. }],
-        _ => panic!("unexpected change"),
+        assert_eq!(text.as_str(), "corge")
-    }
+    );
    vfs.add_file_overlay(&dir.path().join("a/b/spam.rs"), "spam".to_string());
-    let change = vfs.commit_changes().pop().unwrap();
+    assert_match!(
-    match change {
+        vfs.commit_changes().as_slice(),
-        VfsChange::AddFile { text, path, .. } => {
+        [VfsChange::AddFile { text, path, .. }],
-            assert_eq!(&*text, "spam");
+        {
+            assert_eq!(text.as_str(), "spam");
            assert_eq!(path, "spam.rs");
        }
-        _ => panic!("unexpected change"),
+    );
-    }
    vfs.remove_file_overlay(&dir.path().join("a/b/spam.rs"));
-    let change = vfs.commit_changes().pop().unwrap();
+    assert_match!(
-    match change {
+        vfs.commit_changes().as_slice(),
-        VfsChange::RemoveFile { .. } => (),
+        [VfsChange::RemoveFile { path, .. }],
-        _ => panic!("unexpected change"),
+        assert_eq!(path, "spam.rs")
+    );
+    fs::create_dir_all(dir.path().join("a/sub1/sub2")).unwrap();
+    fs::write(dir.path().join("a/sub1/sub2/new.rs"), "new hello").unwrap();
+    process_tasks(&mut vfs, 1);
+    assert_match!(
+        vfs.commit_changes().as_slice(),
+        [VfsChange::AddFile { text, path, .. }],
+        {
+            assert_eq!(text.as_str(), "new hello");
+            assert_eq!(path, "sub1/sub2/new.rs");
+        }
+    );
+    fs::rename(
+        &dir.path().join("a/sub1/sub2/new.rs"),
+        &dir.path().join("a/sub1/sub2/new1.rs"),
+    )
+    .unwrap();
+    process_tasks(&mut vfs, 2);
+    assert_match!(
+        vfs.commit_changes().as_slice(),
+        [VfsChange::RemoveFile {
+            path: removed_path, ..
+        }, VfsChange::AddFile {
+            text,
+            path: added_path,
+            ..
+        }],
+        {
+            assert_eq!(removed_path, "sub1/sub2/new.rs");
+            assert_eq!(added_path, "sub1/sub2/new1.rs");
+            assert_eq!(text.as_str(), "new hello");
+        }
+    );
+    fs::remove_file(&dir.path().join("a/sub1/sub2/new1.rs")).unwrap();
+    process_tasks(&mut vfs, 1);
+    assert_match!(
+        vfs.commit_changes().as_slice(),
+        [VfsChange::RemoveFile { path, .. }],
+        assert_eq!(path, "sub1/sub2/new1.rs")
+    );
+    {
+        vfs.add_file_overlay(&dir.path().join("a/memfile.rs"), "memfile".to_string());
+        assert_match!(
+            vfs.commit_changes().as_slice(),
+            [VfsChange::AddFile { text, .. }],
+            assert_eq!(text.as_str(), "memfile")
+        );
+        fs::write(&dir.path().join("a/memfile.rs"), "ignore me").unwrap();
+        process_tasks(&mut vfs, 1);
+        assert_match!(vfs.commit_changes().as_slice(), []);
    }
+    // should be ignored
+    fs::create_dir_all(dir.path().join("a/target")).unwrap();
+    fs::write(&dir.path().join("a/target/new.rs"), "ignore me").unwrap();
+    assert_match!(
+        vfs.task_receiver().recv_timeout(Duration::from_millis(300)), // slightly more than watcher debounce delay
+        Err(RecvTimeoutError::Timeout)
+    );
    vfs.shutdown().unwrap();
    Ok(())
 }