8 files changed, 48 insertions, 11 deletions

diff --git a/crates/ra_ide_api/src/db.rs b/crates/ra_ide_api/src/db.rs
index cccf0ada4..b3f395502 100644
--- a/crates/ra_ide_api/src/db.rs
+++ b/crates/ra_ide_api/src/db.rs
@@ -41,6 +41,12 @@ impl salsa::Database for RootDatabase {
 
 impl Default for RootDatabase {
     fn default() -> RootDatabase {
+        RootDatabase::new(None)
+    }
+}
+
+impl RootDatabase {
+    pub fn new(lru_capacity: Option<usize>) -> RootDatabase {
         let mut db = RootDatabase {
             runtime: salsa::Runtime::default(),
             last_gc: time::Instant::now(),
@@ -49,9 +55,9 @@ impl Default for RootDatabase {
         db.set_crate_graph(Default::default());
         db.set_local_roots(Default::default());
         db.set_library_roots(Default::default());
-        let lru_cap = ra_db::DEFAULT_LRU_CAP;
-        db.query_mut(ra_db::ParseQuery).set_lru_capacity(lru_cap);
-        db.query_mut(hir::db::ParseMacroQuery).set_lru_capacity(lru_cap);
+        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);
         db
     }
 }
diff --git a/crates/ra_ide_api/src/lib.rs b/crates/ra_ide_api/src/lib.rs
index dbebf50a6..8741e736f 100644
--- a/crates/ra_ide_api/src/lib.rs
+++ b/crates/ra_ide_api/src/lib.rs
@@ -242,12 +242,21 @@ pub struct CallInfo {
 }
 
 /// `AnalysisHost` stores the current state of the world.
-#[derive(Debug, Default)]
+#[derive(Debug)]
 pub struct AnalysisHost {
     db: db::RootDatabase,
 }
 
+impl Default for AnalysisHost {
+    fn default() -> AnalysisHost {
+        AnalysisHost::new(None)
+    }
+}
+
 impl AnalysisHost {
+    pub fn new(lru_capcity: Option<usize>) -> AnalysisHost {
+        AnalysisHost { db: db::RootDatabase::new(lru_capcity) }
+    }
     /// Returns a snapshot of the current state, which you can query for
     /// semantic information.
     pub fn analysis(&self) -> Analysis {
diff --git a/crates/ra_lsp_server/src/init.rs b/crates/ra_lsp_server/src/init.rs
index 1b77e0312..b894b449d 100644
--- a/crates/ra_lsp_server/src/init.rs
+++ b/crates/ra_lsp_server/src/init.rs
@@ -17,11 +17,17 @@ pub struct InitializationOptions {
     /// Defaults to `true`
     #[serde(deserialize_with = "nullable_bool_true")]
     pub show_workspace_loaded: bool,
+
+    pub lru_capacity: Option<usize>,
 }
 
 impl Default for InitializationOptions {
     fn default() -> InitializationOptions {
-        InitializationOptions { publish_decorations: false, show_workspace_loaded: true }
+        InitializationOptions {
+            publish_decorations: false,
+            show_workspace_loaded: true,
+            lru_capacity: None,
+        }
     }
 }
 
@@ -54,8 +60,10 @@ mod test {
         assert_eq!(default, serde_json::from_str(r#"{}"#).unwrap());
         assert_eq!(
             default,
-            serde_json::from_str(r#"{"publishDecorations":null, "showWorkspaceLoaded":null}"#)
-                .unwrap()
+            serde_json::from_str(
+                r#"{"publishDecorations":null, "showWorkspaceLoaded":null, "lruCapacity":null}"#
+            )
+            .unwrap()
         );
     }
 }
diff --git a/crates/ra_lsp_server/src/main_loop.rs b/crates/ra_lsp_server/src/main_loop.rs
index 090fb9b1b..0790ea472 100644
--- a/crates/ra_lsp_server/src/main_loop.rs
+++ b/crates/ra_lsp_server/src/main_loop.rs
@@ -73,7 +73,7 @@ pub fn main_loop(
         loaded_workspaces
     };
 
-    let mut state = WorldState::new(ws_roots, workspaces);
+    let mut state = WorldState::new(ws_roots, workspaces, options.lru_capacity);
 
     let pool = ThreadPool::new(THREADPOOL_SIZE);
     let (task_sender, task_receiver) = unbounded::<Task>();
diff --git a/crates/ra_lsp_server/src/world.rs b/crates/ra_lsp_server/src/world.rs
index cd8df4fdb..f9ce570ca 100644
--- a/crates/ra_lsp_server/src/world.rs
+++ b/crates/ra_lsp_server/src/world.rs
@@ -46,7 +46,11 @@ pub struct WorldSnapshot {
 }
 
 impl WorldState {
-    pub fn new(folder_roots: Vec<PathBuf>, workspaces: Vec<ProjectWorkspace>) -> WorldState {
+    pub fn new(
+        folder_roots: Vec<PathBuf>,
+        workspaces: Vec<ProjectWorkspace>,
+        lru_capacity: Option<usize>,
+    ) -> WorldState {
         let mut change = AnalysisChange::new();
 
         let mut roots = Vec::new();
@@ -74,7 +78,7 @@ impl WorldState {
         }
         change.set_crate_graph(crate_graph);
 
-        let mut analysis_host = AnalysisHost::default();
+        let mut analysis_host = AnalysisHost::new(lru_capacity);
         analysis_host.apply_change(change);
         WorldState {
             roots_to_scan,
diff --git a/editors/code/package.json b/editors/code/package.json
index 05c808394..c2ed8d126 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -232,6 +232,11 @@
                     ],
                     "default": "off",
                     "description": "Trace output of cargo-watch"
+                },
+                "rust-analyzer.lruCapacity": {
+                    "type": "number",
+                    "default": null,
+                    "description": "Number of syntax trees rust-analyzer keeps in memory"
                 }
             }
         },
diff --git a/editors/code/src/config.ts b/editors/code/src/config.ts
index 8d73a6b34..3024546d2 100644
--- a/editors/code/src/config.ts
+++ b/editors/code/src/config.ts
@@ -19,6 +19,7 @@ export class Config {
     public enableEnhancedTyping = true;
     public raLspServerPath = RA_LSP_DEBUG || 'ra_lsp_server';
     public showWorkspaceLoadedNotification = true;
+    public lruCapacity: null | number = null;
     public cargoWatchOptions: CargoWatchOptions = {
         enableOnStartup: 'ask',
         trace: 'off',
@@ -109,5 +110,8 @@ export class Config {
                 ''
             );
         }
+        if (config.has('lruCapacity')) {
+            this.lruCapacity = config.get('lruCapacity') as number;
+        }
     }
 }
diff --git a/editors/code/src/server.ts b/editors/code/src/server.ts
index 81c2b3fff..7029142fd 100644
--- a/editors/code/src/server.ts
+++ b/editors/code/src/server.ts
@@ -35,7 +35,8 @@ export class Server {
             initializationOptions: {
                 publishDecorations: true,
                 showWorkspaceLoaded:
-                    Server.config.showWorkspaceLoadedNotification
+                    Server.config.showWorkspaceLoadedNotification,
+                lruCapacity: Server.config.lruCapacity
             },
             traceOutputChannel
         };