4 files changed, 55 insertions, 45 deletions

diff --git a/Cargo.lock b/Cargo.lock
index bf937d205..fd1fb5ea5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -268,7 +268,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.16 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "synstructure 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -484,7 +484,7 @@ dependencies = [
  "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc-macro2 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.16 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.17 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -608,7 +608,7 @@ dependencies = [
  "rayon 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "relative-path 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "salsa 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "salsa 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "test_utils 0.1.0",
 ]
 
@@ -836,7 +836,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "salsa"
-version = "0.7.0"
+version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "derive-new 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -890,7 +890,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.16 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.17 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -965,7 +965,7 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "0.15.16"
+version = "0.15.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -980,7 +980,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.16 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -995,7 +995,7 @@ dependencies = [
 
 [[package]]
 name = "tera"
-version = "0.11.18"
+version = "0.11.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "chrono 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1021,7 +1021,7 @@ dependencies = [
  "failure 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "heck 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "ron 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "tera 0.11.18 (registry+https://github.com/rust-lang/crates.io-index)",
+ "tera 0.11.19 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1352,7 +1352,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "138e3e0acb6c9fb258b19b67cb8abd63c00679d2851805ea151465464fe9030a"
 "checksum ryu 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "7153dd96dade874ab973e098cb62fcdbb89a03682e46b144fd09550998d4a4a7"
 "checksum safemem 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "8dca453248a96cb0749e36ccdfe2b0b4e54a61bfef89fb97ec621eb8e0a93dd9"
-"checksum salsa 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ef0f1fb2a01d4579b6658343b1b5431a72c62c186ebb9b40bd6cd3078c7afecf"
+"checksum salsa 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e56b13ce9b2bfaa1c89863d76880838c0734de85beeaef437fd70d4fa7e253d3"
 "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"
@@ -1368,10 +1368,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum strsim 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "bb4f380125926a99e52bc279241539c018323fab05ad6368b56f93d9369ff550"
 "checksum superslice 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b50b13d42370e0f5fc62eafdd5c2d20065eaf5458dab215ff3e20e63eea96b30"
 "checksum syn 0.14.9 (registry+https://github.com/rust-lang/crates.io-index)" = "261ae9ecaa397c42b960649561949d69311f08eeaea86a65696e6e46517cf741"
-"checksum syn 0.15.16 (registry+https://github.com/rust-lang/crates.io-index)" = "0b78d53b5e1b6e63129140b1336877c3bddbae398c7956150396bdad0e28676c"
+"checksum syn 0.15.17 (registry+https://github.com/rust-lang/crates.io-index)" = "3391038ebc3e4ab24eb028cb0ef2f2dc4ba0cbf72ee895ed6a6fad730640b5bc"
 "checksum synstructure 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)" = "73687139bf99285483c96ac0add482c3776528beac1d97d444f6e91f203a2015"
 "checksum tempdir 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)" = "15f2b5fb00ccdf689e0149d1b1b3c03fead81c2b37735d812fa8bddbbf41b6d8"
-"checksum tera 0.11.18 (registry+https://github.com/rust-lang/crates.io-index)" = "6c87cae42cc4fc480278c7583792cc5da2d51a25be916b7921cbb45c43063b8d"
+"checksum tera 0.11.19 (registry+https://github.com/rust-lang/crates.io-index)" = "6ac6d8ad623a7efcfb4367ce2a36f84ef849d5aa3c7bcf2e0324c4cbcc57ebaf"
 "checksum teraron 0.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "0d89ad4617d1dec55331067fadaa041e813479e1779616f3d3ce9308bf46184e"
 "checksum termion 1.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "689a3bdfaab439fd92bc87df5c4c78417d3cbe537487274e9b0b2dce76e92096"
 "checksum text_unit 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "8009d7bdbd896a7e09b595f8f9325a19047fc708653e60d0895202b82135048f"
diff --git a/crates/ra_analysis/Cargo.toml b/crates/ra_analysis/Cargo.toml
index deddf41f0..908ee1c81 100644
--- a/crates/ra_analysis/Cargo.toml
+++ b/crates/ra_analysis/Cargo.toml
@@ -9,7 +9,7 @@ log = "0.4.5"
 relative-path = "0.4.0"
 rayon = "1.0.2"
 fst = "0.3.1"
-salsa = "0.7.0"
+salsa = "0.8.0"
 rustc-hash = "1.0"
 ra_syntax = { path = "../ra_syntax" }
 ra_editor = { path = "../ra_editor" }
diff --git a/crates/ra_analysis/src/db.rs b/crates/ra_analysis/src/db.rs
index 94fdd36a4..9548ec602 100644
--- a/crates/ra_analysis/src/db.rs
+++ b/crates/ra_analysis/src/db.rs
@@ -35,16 +35,10 @@ pub(crate) fn check_canceled(db: &impl salsa::Database) -> Cancelable<()> {
 }
 
 impl salsa::ParallelDatabase for RootDatabase {
-    fn fork(&self) -> Self {
-        RootDatabase {
-            runtime: self.runtime.fork(),
-        }
-    }
-}
-
-impl Clone for RootDatabase {
-    fn clone(&self) -> RootDatabase {
-        salsa::ParallelDatabase::fork(self)
+    fn snapshot(&self) -> salsa::Snapshot<RootDatabase> {
+        salsa::Snapshot::new(RootDatabase {
+            runtime: self.runtime.snapshot(self),
+        })
     }
 }
 
diff --git a/crates/ra_analysis/src/imp.rs b/crates/ra_analysis/src/imp.rs
index 060e2b606..77dd71dcf 100644
--- a/crates/ra_analysis/src/imp.rs
+++ b/crates/ra_analysis/src/imp.rs
@@ -1,4 +1,5 @@
 use std::{
+    fmt,
     hash::{Hash, Hasher},
     sync::Arc,
 };
@@ -92,18 +93,18 @@ pub(crate) struct AnalysisHostImpl {
 
 impl AnalysisHostImpl {
     pub fn new() -> AnalysisHostImpl {
-        let db = db::RootDatabase::default();
-        db.query(crate::input::SourceRootQuery)
+        let mut db = db::RootDatabase::default();
+        db.query_mut(crate::input::SourceRootQuery)
             .set(WORKSPACE, Default::default());
-        db.query(crate::input::CrateGraphQuery)
+        db.query_mut(crate::input::CrateGraphQuery)
             .set((), Default::default());
-        db.query(crate::input::LibrariesQuery)
+        db.query_mut(crate::input::LibrariesQuery)
             .set((), Default::default());
         AnalysisHostImpl { db }
     }
     pub fn analysis(&self) -> AnalysisImpl {
         AnalysisImpl {
-            db: self.db.fork(), // freeze revision here
+            db: self.db.snapshot(),
         }
     }
     pub fn apply_change(&mut self, change: AnalysisChange) {
@@ -111,7 +112,7 @@ impl AnalysisHostImpl {
 
         for (file_id, text) in change.files_changed {
             self.db
-                .query(crate::input::FileTextQuery)
+                .query_mut(crate::input::FileTextQuery)
                 .set(file_id, Arc::new(text))
         }
         if !(change.files_added.is_empty() && change.files_removed.is_empty()) {
@@ -121,22 +122,22 @@ impl AnalysisHostImpl {
             let mut source_root = SourceRoot::clone(&self.db.source_root(WORKSPACE));
             for (file_id, text) in change.files_added {
                 self.db
-                    .query(crate::input::FileTextQuery)
+                    .query_mut(crate::input::FileTextQuery)
                     .set(file_id, Arc::new(text));
                 self.db
-                    .query(crate::input::FileSourceRootQuery)
+                    .query_mut(crate::input::FileSourceRootQuery)
                     .set(file_id, crate::input::WORKSPACE);
                 source_root.files.insert(file_id);
             }
             for file_id in change.files_removed {
                 self.db
-                    .query(crate::input::FileTextQuery)
+                    .query_mut(crate::input::FileTextQuery)
                     .set(file_id, Arc::new(String::new()));
                 source_root.files.remove(&file_id);
             }
             source_root.file_resolver = file_resolver;
             self.db
-                .query(crate::input::SourceRootQuery)
+                .query_mut(crate::input::SourceRootQuery)
                 .set(WORKSPACE, Arc::new(source_root))
         }
         if !change.libraries_added.is_empty() {
@@ -148,10 +149,10 @@ impl AnalysisHostImpl {
                 for (file_id, text) in library.files {
                     files.insert(file_id);
                     self.db
-                        .query(crate::input::FileSourceRootQuery)
+                        .query_mut(crate::input::FileSourceRootQuery)
                         .set_constant(file_id, source_root_id);
                     self.db
-                        .query(crate::input::FileTextQuery)
+                        .query_mut(crate::input::FileTextQuery)
                         .set_constant(file_id, Arc::new(text));
                 }
                 let source_root = SourceRoot {
@@ -159,27 +160,33 @@ impl AnalysisHostImpl {
                     file_resolver: library.file_resolver,
                 };
                 self.db
-                    .query(crate::input::SourceRootQuery)
+                    .query_mut(crate::input::SourceRootQuery)
                     .set(source_root_id, Arc::new(source_root));
                 self.db
-                    .query(crate::input::LibrarySymbolsQuery)
+                    .query_mut(crate::input::LibrarySymbolsQuery)
                     .set(source_root_id, Arc::new(library.symbol_index));
             }
             self.db
-                .query(crate::input::LibrariesQuery)
+                .query_mut(crate::input::LibrariesQuery)
                 .set((), Arc::new(libraries));
         }
         if let Some(crate_graph) = change.crate_graph {
             self.db
-                .query(crate::input::CrateGraphQuery)
+                .query_mut(crate::input::CrateGraphQuery)
                 .set((), Arc::new(crate_graph))
         }
     }
 }
 
-#[derive(Debug)]
 pub(crate) struct AnalysisImpl {
-    pub(crate) db: db::RootDatabase,
+    pub(crate) db: salsa::Snapshot<db::RootDatabase>,
+}
+
+impl fmt::Debug for AnalysisImpl {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let db: &db::RootDatabase = &self.db;
+        fmt.debug_struct("AnalysisImpl").field("db", db).finish()
+    }
 }
 
 impl AnalysisImpl {
@@ -198,10 +205,19 @@ impl AnalysisImpl {
                 .collect()
         } else {
             let files = &self.db.source_root(WORKSPACE).files;
-            let db = self.db.clone();
+
+            /// Need to wrap Snapshot to provide `Clon` impl for `map_with`
+            struct Snap(salsa::Snapshot<db::RootDatabase>);
+            impl Clone for Snap {
+                fn clone(&self) -> Snap {
+                    Snap(self.0.snapshot())
+                }
+            }
+
+            let snap = Snap(self.db.snapshot());
             files
                 .par_iter()
-                .map_with(db, |db, &file_id| db.file_symbols(file_id))
+                .map_with(snap, |db, &file_id| db.0.file_symbols(file_id))
                 .filter_map(|it| it.ok())
                 .collect()
         };
@@ -229,7 +245,7 @@ impl AnalysisImpl {
                         return None;
                     }
                 };
-                let decl = link.bind_source(&module_tree, &self.db);
+                let decl = link.bind_source(&module_tree, &*self.db);
                 let decl = decl.ast();
 
                 let sym = FileSymbol {
@@ -371,7 +387,7 @@ impl AnalysisImpl {
             })
             .collect::<Vec<_>>();
         if let Some(m) = module_tree.any_module_for_file(file_id) {
-            for (name_node, problem) in m.problems(&module_tree, &self.db) {
+            for (name_node, problem) in m.problems(&module_tree, &*self.db) {
                 let diag = match problem {
                     Problem::UnresolvedModule { candidate } => {
                         let create_file = FileSystemEdit::CreateFile {