Merge #1445

1445: Use the new "durability" infrastructure from salsa r=matklad a=matklad

Based on https://github.com/nikomatsakis/salsa/tree/durability

Durability allows us to skip *validation* work for sysroot and crates.io libraries, which massively speeds up some workloads



Co-authored-by: Aleksey Kladov <[email protected]>

10 files changed, 166 insertions, 68 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 365b77f41..572e2f424 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -298,6 +298,19 @@ dependencies = [
 ]
 
 [[package]]
+name = "crossbeam"
+version = "0.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-channel 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-deque 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-epoch 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-queue 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-utils 0.6.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "crossbeam-channel"
 version = "0.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -315,6 +328,15 @@ dependencies = [
 ]
 
 [[package]]
+name = "crossbeam-deque"
+version = "0.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "crossbeam-epoch 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-utils 0.6.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "crossbeam-epoch"
 version = "0.7.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -360,7 +382,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.42 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.43 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -450,7 +472,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.42 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.43 (registry+https://github.com/rust-lang/crates.io-index)",
  "synstructure 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -910,7 +932,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.42 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.43 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1030,7 +1052,7 @@ dependencies = [
  "proc-macro-hack 0.5.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.42 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.43 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1064,7 +1086,7 @@ dependencies = [
  "pest_meta 2.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.42 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.43 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1098,7 +1120,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.42 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.43 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1197,7 +1219,7 @@ dependencies = [
  "ra_syntax 0.1.0",
  "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 0.12.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "salsa 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1658,29 +1680,29 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "salsa"
-version = "0.12.3"
+version = "0.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
+ "crossbeam 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "derive-new 0.5.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "indexmap 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "linked-hash-map 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "lock_api 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "parking_lot 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "salsa-macros 0.12.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "salsa-macros 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "salsa-macros"
-version = "0.12.1"
+version = "0.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "heck 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.42 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.43 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1725,7 +1747,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.42 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.43 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1809,7 +1831,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "syn"
-version = "0.15.42"
+version = "0.15.43"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1824,7 +1846,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.42 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.43 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -2169,8 +2191,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "ddfc5b9aa5d4507acaf872de71051dfd0e309860e88966e1051e462a077aac4f"
 "checksum console 0.7.7 (registry+https://github.com/rust-lang/crates.io-index)" = "8ca57c2c14b8a2bf3105bc9d15574aad80babf6a9c44b1058034cdf8bd169628"
 "checksum cpuprofiler 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "33f07976bb6821459632d7a18d97ccca005cb5c552f251f822c7c1781c1d7035"
+"checksum crossbeam 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)" = "2d818a4990769aac0c7ff1360e233ef3a41adcb009ebb2036bf6915eb0f6b23c"
 "checksum crossbeam-channel 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)" = "c8ec7fcd21571dc78f96cc96243cab8d8f035247c3efd16c687be154c3fa9efa"
 "checksum crossbeam-deque 0.6.3 (registry+https://github.com/rust-lang/crates.io-index)" = "05e44b8cf3e1a625844d1750e1f7820da46044ff6d28f4d43e455ba3e5bb2c13"
+"checksum crossbeam-deque 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)" = "b18cd2e169ad86297e6bc0ad9aa679aee9daa4f19e8163860faf7c164e4f5a71"
 "checksum crossbeam-epoch 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)" = "fedcd6772e37f3da2a9af9bf12ebe046c0dfe657992377b4df982a2b54cd37a9"
 "checksum crossbeam-queue 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7c979cd6cfe72335896575c6b5688da489e420d36a27a0b9eb0c73db574b4a4b"
 "checksum crossbeam-utils 0.6.6 (registry+https://github.com/rust-lang/crates.io-index)" = "04973fa96e96579258a5091af6003abde64af786b860f18622b82e026cca60e6"
@@ -2300,8 +2324,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7540fc8b0c49f096ee9c961cda096467dce8084bec6bdca2fc83895fd9b28cb8"
 "checksum rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "138e3e0acb6c9fb258b19b67cb8abd63c00679d2851805ea151465464fe9030a"
 "checksum ryu 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c92464b447c0ee8c4fb3824ecc8383b81717b9f1e74ba2e72540aef7b9f82997"
-"checksum salsa 0.12.3 (registry+https://github.com/rust-lang/crates.io-index)" = "2891cd628406e8a0ca714b827511de1bff76f796e3382cc72a3de732ccad5aea"
-"checksum salsa-macros 0.12.1 (registry+https://github.com/rust-lang/crates.io-index)" = "b7f1e25ca2b995bdf032946174929d62156ffd57abd7ff88dc6f9bdeb5ac0c59"
+"checksum salsa 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e3265a2a9bbd384bd2a9f9511c2c18fb41f62c412516052e8934517dc8ff64f1"
+"checksum salsa-macros 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)" = "377ce29c5660dcc5c3f66660a7e49940b8328e3d940255ef9d4c2be1f7b474a9"
 "checksum same-file 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)" = "585e8ddcedc187886a30fa705c47985c3fa88d06624095856b36ca0b82ff4421"
 "checksum scopeguard 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b42e15e59b18a828bbf5c58ea01debb36b9b096346de35d941dcb89009f24a0d"
 "checksum semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1d7eb9ef2c18661902cc47e535f9bc51b78acd254da71d375c2f6720d9a40403"
@@ -2318,7 +2342,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum stacker 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "fb79482f57cf598af52094ec4cc3b3c42499d3ce5bd426f2ac41515b7e57404b"
 "checksum strsim 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a"
 "checksum superslice 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ab16ced94dbd8a46c82fd81e3ed9a8727dac2977ea869d217bcc4ea1f122e81f"
-"checksum syn 0.15.42 (registry+https://github.com/rust-lang/crates.io-index)" = "eadc09306ca51a40555dd6fc2b415538e9e18bc9f870e47b1a524a79fe2dcf5e"
+"checksum syn 0.15.43 (registry+https://github.com/rust-lang/crates.io-index)" = "ee06ea4b620ab59a2267c6b48be16244a3389f8bfa0986bdd15c35b890b00af3"
 "checksum synstructure 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)" = "02353edf96d6e4dc81aea2d8490a7e9db177bf8acb0e951c24940bf866cb313f"
 "checksum tempfile 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7a6e24d9338a0a5be79593e2fa15a648add6138caa803e2d5bc782c371732ca9"
 "checksum tera 0.11.20 (registry+https://github.com/rust-lang/crates.io-index)" = "4b505279e19d8f7d24b1a9dc58327c9c36174b1a2c7ebdeac70792d017cb64f3"
diff --git a/crates/ra_cli/src/analysis_bench.rs b/crates/ra_cli/src/analysis_bench.rs
index 5e9d0c16d..9e76bcebf 100644
--- a/crates/ra_cli/src/analysis_bench.rs
+++ b/crates/ra_cli/src/analysis_bench.rs
@@ -1,10 +1,14 @@
 use std::{
     path::{Path, PathBuf},
+    sync::Arc,
     time::Instant,
 };
 
-use ra_db::{salsa::Database, SourceDatabase};
-use ra_ide_api::{Analysis, AnalysisHost, FilePosition, LineCol};
+use ra_db::{
+    salsa::{Database, Durability},
+    FileId, SourceDatabase,
+};
+use ra_ide_api::{Analysis, AnalysisChange, AnalysisHost, FilePosition, LineCol};
 
 use crate::Result;
 
@@ -16,7 +20,7 @@ pub(crate) enum Op {
 pub(crate) fn run(verbose: bool, path: &Path, op: Op) -> Result<()> {
     let start = Instant::now();
     eprint!("loading: ");
-    let (host, roots) = ra_batch::load_cargo(path)?;
+    let (mut host, roots) = ra_batch::load_cargo(path)?;
     let db = host.raw_database();
     eprintln!("{:?}\n", start.elapsed());
 
@@ -44,7 +48,7 @@ pub(crate) fn run(verbose: bool, path: &Path, op: Op) -> Result<()> {
 
     match op {
         Op::Highlight { .. } => {
-            let res = do_work(&host, |analysis| {
+            let res = do_work(&mut host, file_id, |analysis| {
                 analysis.diagnostics(file_id).unwrap();
                 analysis.highlight_as_html(file_id, false).unwrap()
             });
@@ -59,7 +63,7 @@ pub(crate) fn run(verbose: bool, path: &Path, op: Op) -> Result<()> {
                 .offset(LineCol { line, col_utf16: column });
             let file_postion = FilePosition { file_id, offset };
 
-            let res = do_work(&host, |analysis| analysis.completions(file_postion));
+            let res = do_work(&mut host, file_id, |analysis| analysis.completions(file_postion));
             if verbose {
                 println!("\n{:#?}", res);
             }
@@ -68,7 +72,7 @@ pub(crate) fn run(verbose: bool, path: &Path, op: Op) -> Result<()> {
     Ok(())
 }
 
-fn do_work<F: Fn(&Analysis) -> T, T>(host: &AnalysisHost, work: F) -> T {
+fn do_work<F: Fn(&Analysis) -> T, T>(host: &mut AnalysisHost, file_id: FileId, work: F) -> T {
     {
         let start = Instant::now();
         eprint!("from scratch:   ");
@@ -84,7 +88,27 @@ fn do_work<F: Fn(&Analysis) -> T, T>(host: &AnalysisHost, work: F) -> T {
     {
         let start = Instant::now();
         eprint!("trivial change: ");
-        host.raw_database().salsa_runtime().next_revision();
+        host.raw_database().salsa_runtime().synthetic_write(Durability::LOW);
+        work(&host.analysis());
+        eprintln!("{:?}", start.elapsed());
+    }
+    {
+        let start = Instant::now();
+        eprint!("comment change: ");
+        {
+            let mut text = host.analysis().file_text(file_id).unwrap().to_string();
+            text.push_str("\n/* Hello world */\n");
+            let mut change = AnalysisChange::new();
+            change.change_file(file_id, Arc::new(text));
+            host.apply_change(change);
+        }
+        work(&host.analysis());
+        eprintln!("{:?}", start.elapsed());
+    }
+    {
+        let start = Instant::now();
+        eprint!("const change:   ");
+        host.raw_database().salsa_runtime().synthetic_write(Durability::HIGH);
         let res = work(&host.analysis());
         eprintln!("{:?}", start.elapsed());
         res
diff --git a/crates/ra_db/Cargo.toml b/crates/ra_db/Cargo.toml
index 7a13c247b..2fac07bc5 100644
--- a/crates/ra_db/Cargo.toml
+++ b/crates/ra_db/Cargo.toml
@@ -5,7 +5,7 @@ version = "0.1.0"
 authors = ["rust-analyzer developers"]
 
 [dependencies]
-salsa = "0.12.3"
+salsa = "0.13.0"
 relative-path = "0.4.0"
 rustc-hash = "1.0"
 
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index 358365176..7b7974f5b 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -1,6 +1,5 @@
 use std::sync::Arc;
 
-use parking_lot::Mutex;
 use ra_db::{salsa, SourceDatabase};
 use ra_syntax::{ast, Parse, SmolStr, SyntaxNode};
 
@@ -147,6 +146,7 @@ pub trait DefDatabase: InternDatabase {
 }
 
 #[salsa::query_group(HirDatabaseStorage)]
+#[salsa::requires(salsa::Database)]
 pub trait HirDatabase: DefDatabase + AstDatabase {
     #[salsa::invoke(ExprScopes::expr_scopes_query)]
     fn expr_scopes(&self, def: DefWithBody) -> Arc<ExprScopes>;
@@ -187,11 +187,10 @@ pub trait HirDatabase: DefDatabase + AstDatabase {
     /// This provides the Chalk trait solver instance. Because Chalk always
     /// works from a specific crate, this query is keyed on the crate; and
     /// because Chalk does its own internal caching, the solver is wrapped in a
-    /// Mutex and the query is marked volatile, to make sure the cached state is
-    /// thrown away when input facts change.
+    /// Mutex and the query does an untracked read internally, to make sure the
+    /// cached state is thrown away when input facts change.
     #[salsa::invoke(crate::ty::traits::trait_solver_query)]
-    #[salsa::volatile]
-    fn trait_solver(&self, krate: Crate) -> Arc<Mutex<crate::ty::traits::Solver>>;
+    fn trait_solver(&self, krate: Crate) -> crate::ty::traits::TraitSolver;
 
     #[salsa::invoke(crate::ty::traits::chalk::associated_ty_data_query)]
     fn associated_ty_data(&self, id: chalk_ir::TypeId) -> Arc<chalk_rust_ir::AssociatedTyDatum>;
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 081974e2b..018fcd096 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -1,3 +1,5 @@
+#![recursion_limit = "512"]
+
 //! HIR (previously known as descriptors) provides a high-level object oriented
 //! access to Rust code.
 //!
diff --git a/crates/ra_hir/src/ty/traits.rs b/crates/ra_hir/src/ty/traits.rs
index fde5d8a47..b634f0b79 100644
--- a/crates/ra_hir/src/ty/traits.rs
+++ b/crates/ra_hir/src/ty/traits.rs
@@ -4,6 +4,7 @@ use std::sync::Arc;
 use chalk_ir::cast::Cast;
 use log::debug;
 use parking_lot::Mutex;
+use ra_db::salsa;
 use ra_prof::profile;
 use rustc_hash::FxHashSet;
 
@@ -14,7 +15,34 @@ use self::chalk::{from_chalk, ToChalk};
 
 pub(crate) mod chalk;
 
-pub(crate) type Solver = chalk_solve::Solver;
+#[derive(Debug, Clone)]
+pub struct TraitSolver {
+    krate: Crate,
+    inner: Arc<Mutex<chalk_solve::Solver>>,
+}
+
+/// We need eq for salsa
+impl PartialEq for TraitSolver {
+    fn eq(&self, other: &TraitSolver) -> bool {
+        Arc::ptr_eq(&self.inner, &other.inner)
+    }
+}
+
+impl Eq for TraitSolver {}
+
+impl TraitSolver {
+    fn solve(
+        &self,
+        db: &impl HirDatabase,
+        goal: &chalk_ir::UCanonical<chalk_ir::InEnvironment<chalk_ir::Goal>>,
+    ) -> Option<chalk_solve::Solution> {
+        let context = ChalkContext { db, krate: self.krate };
+        debug!("solve goal: {:?}", goal);
+        let solution = self.inner.lock().solve(&context, goal);
+        debug!("solve({:?}) => {:?}", goal, solution);
+        solution
+    }
+}
 
 /// This controls the maximum size of types Chalk considers. If we set this too
 /// high, we can run into slow edge cases; if we set it too low, Chalk won't
@@ -27,11 +55,15 @@ struct ChalkContext<'a, DB> {
     krate: Crate,
 }
 
-pub(crate) fn trait_solver_query(_db: &impl HirDatabase, _krate: Crate) -> Arc<Mutex<Solver>> {
+pub(crate) fn trait_solver_query(
+    db: &(impl HirDatabase + salsa::Database),
+    krate: Crate,
+) -> TraitSolver {
+    db.salsa_runtime().report_untracked_read();
     // krate parameter is just so we cache a unique solver per crate
     let solver_choice = chalk_solve::SolverChoice::SLG { max_size: CHALK_SOLVER_MAX_SIZE };
-    debug!("Creating new solver for crate {:?}", _krate);
-    Arc::new(Mutex::new(solver_choice.into_solver()))
+    debug!("Creating new solver for crate {:?}", krate);
+    TraitSolver { krate, inner: Arc::new(Mutex::new(solver_choice.into_solver())) }
 }
 
 /// Collects impls for the given trait in the whole dependency tree of `krate`.
@@ -54,18 +86,6 @@ pub(crate) fn impls_for_trait_query(
     impls.into_iter().collect::<Vec<_>>().into()
 }
 
-fn solve(
-    db: &impl HirDatabase,
-    krate: Crate,
-    goal: &chalk_ir::UCanonical<chalk_ir::InEnvironment<chalk_ir::Goal>>,
-) -> Option<chalk_solve::Solution> {
-    let context = ChalkContext { db, krate };
-    let solver = db.trait_solver(krate);
-    let solution = solver.lock().solve(&context, goal);
-    debug!("solve({:?}) => {:?}", goal, solution);
-    solution
-}
-
 /// A set of clauses that we assume to be true. E.g. if we are inside this function:
 /// ```rust
 /// fn foo<T: Default>(t: T) {}
@@ -127,7 +147,7 @@ pub(crate) fn trait_solve_query(
     // We currently don't deal with universes (I think / hope they're not yet
     // relevant for our use cases?)
     let u_canonical = chalk_ir::UCanonical { canonical, universes: 1 };
-    let solution = solve(db, krate, &u_canonical);
+    let solution = db.trait_solver(krate).solve(db, &u_canonical);
     solution.map(|solution| solution_from_chalk(db, solution))
 }
 
diff --git a/crates/ra_ide_api/src/change.rs b/crates/ra_ide_api/src/change.rs
index 147d2b21d..0234c572d 100644
--- a/crates/ra_ide_api/src/change.rs
+++ b/crates/ra_ide_api/src/change.rs
@@ -1,7 +1,7 @@
 use std::{fmt, sync::Arc, time};
 
 use ra_db::{
-    salsa::{Database, SweepStrategy},
+    salsa::{Database, Durability, SweepStrategy},
     CrateGraph, FileId, SourceDatabase, SourceRoot, SourceRootId,
 };
 use ra_prof::{memory_usage, profile, Bytes};
@@ -155,54 +155,71 @@ impl RootDatabase {
         log::info!("apply_change {:?}", change);
         {
             let _p = profile("RootDatabase::apply_change/cancellation");
-            self.salsa_runtime().next_revision();
+            self.salsa_runtime().synthetic_write(Durability::LOW);
         }
         if !change.new_roots.is_empty() {
             let mut local_roots = Vec::clone(&self.local_roots());
             for (root_id, is_local) in change.new_roots {
                 let root = if is_local { SourceRoot::new() } else { SourceRoot::new_library() };
-                self.set_source_root(root_id, Arc::new(root));
+                let durability = durability(&root);
+                self.set_source_root_with_durability(root_id, Arc::new(root), durability);
                 if is_local {
                     local_roots.push(root_id);
                 }
             }
-            self.set_local_roots(Arc::new(local_roots));
+            self.set_local_roots_with_durability(Arc::new(local_roots), Durability::HIGH);
         }
 
         for (root_id, root_change) in change.roots_changed {
             self.apply_root_change(root_id, root_change);
         }
         for (file_id, text) in change.files_changed {
-            self.set_file_text(file_id, text)
+            let source_root_id = self.file_source_root(file_id);
+            let source_root = self.source_root(source_root_id);
+            let durability = durability(&source_root);
+            self.set_file_text_with_durability(file_id, text, durability)
         }
         if !change.libraries_added.is_empty() {
             let mut libraries = Vec::clone(&self.library_roots());
             for library in change.libraries_added {
                 libraries.push(library.root_id);
-                self.set_source_root(library.root_id, Default::default());
-                self.set_constant_library_symbols(library.root_id, Arc::new(library.symbol_index));
+                self.set_source_root_with_durability(
+                    library.root_id,
+                    Default::default(),
+                    Durability::HIGH,
+                );
+                self.set_library_symbols_with_durability(
+                    library.root_id,
+                    Arc::new(library.symbol_index),
+                    Durability::HIGH,
+                );
                 self.apply_root_change(library.root_id, library.root_change);
             }
-            self.set_library_roots(Arc::new(libraries));
+            self.set_library_roots_with_durability(Arc::new(libraries), Durability::HIGH);
         }
         if let Some(crate_graph) = change.crate_graph {
-            self.set_crate_graph(Arc::new(crate_graph))
+            self.set_crate_graph_with_durability(Arc::new(crate_graph), Durability::HIGH)
         }
     }
 
     fn apply_root_change(&mut self, root_id: SourceRootId, root_change: RootChange) {
         let mut source_root = SourceRoot::clone(&self.source_root(root_id));
+        let durability = durability(&source_root);
         for add_file in root_change.added {
-            self.set_file_text(add_file.file_id, add_file.text);
-            self.set_file_relative_path(add_file.file_id, add_file.path.clone());
-            self.set_file_source_root(add_file.file_id, root_id);
+            self.set_file_text_with_durability(add_file.file_id, add_file.text, durability);
+            self.set_file_relative_path_with_durability(
+                add_file.file_id,
+                add_file.path.clone(),
+                durability,
+            );
+            self.set_file_source_root_with_durability(add_file.file_id, root_id, durability);
             source_root.files.insert(add_file.path, add_file.file_id);
         }
         for remove_file in root_change.removed {
-            self.set_file_text(remove_file.file_id, Default::default());
+            self.set_file_text_with_durability(remove_file.file_id, Default::default(), durability);
             source_root.files.remove(&remove_file.path);
         }
-        self.set_source_root(root_id, Arc::new(source_root));
+        self.set_source_root_with_durability(root_id, Arc::new(source_root), durability);
     }
 
     pub(crate) fn maybe_collect_garbage(&mut self) {
@@ -308,3 +325,11 @@ impl RootDatabase {
         acc
     }
 }
+
+fn durability(source_root: &SourceRoot) -> Durability {
+    if source_root.is_library {
+        Durability::HIGH
+    } else {
+        Durability::LOW
+    }
+}
diff --git a/crates/ra_ide_api/src/db.rs b/crates/ra_ide_api/src/db.rs
index 44216b045..fc8252e4b 100644
--- a/crates/ra_ide_api/src/db.rs
+++ b/crates/ra_ide_api/src/db.rs
@@ -1,7 +1,7 @@
 use std::{sync::Arc, time};
 
 use ra_db::{
-    salsa::{self, Database},
+    salsa::{self, Database, Durability},
     Canceled, CheckCanceled, FileId, SourceDatabase,
 };
 
@@ -57,9 +57,9 @@ impl RootDatabase {
             last_gc: time::Instant::now(),
             last_gc_check: time::Instant::now(),
         };
-        db.set_crate_graph(Default::default());
-        db.set_local_roots(Default::default());
-        db.set_library_roots(Default::default());
+        db.set_crate_graph_with_durability(Default::default(), Durability::HIGH);
+        db.set_local_roots_with_durability(Default::default(), Durability::HIGH);
+        db.set_library_roots_with_durability(Default::default(), Durability::HIGH);
         let lru_capacity = lru_capacity.unwrap_or(ra_db::DEFAULT_LRU_CAP);
         db.query_mut(ra_db::ParseQuery).set_lru_capacity(lru_capacity);
         db.query_mut(hir::db::ParseMacroQuery).set_lru_capacity(lru_capacity);
diff --git a/crates/ra_ide_api/src/lib.rs b/crates/ra_ide_api/src/lib.rs
index edb646c11..fa4ae4379 100644
--- a/crates/ra_ide_api/src/lib.rs
+++ b/crates/ra_ide_api/src/lib.rs
@@ -281,6 +281,9 @@ impl AnalysisHost {
     pub fn raw_database(&self) -> &(impl hir::db::HirDatabase + salsa::Database) {
         &self.db
     }
+    pub fn raw_database_mut(&mut self) -> &mut (impl hir::db::HirDatabase + salsa::Database) {
+        &mut self.db
+    }
 }
 
 /// Analysis is a snapshot of a world state at a moment in time. It is the main
diff --git a/crates/ra_lsp_server/src/lib.rs b/crates/ra_lsp_server/src/lib.rs
index 795f86383..ca388e472 100644
--- a/crates/ra_lsp_server/src/lib.rs
+++ b/crates/ra_lsp_server/src/lib.rs
@@ -1,3 +1,4 @@
+#![recursion_limit = "512"]
 mod caps;
 mod cargo_target_spec;
 mod conv;