Do not unnecessarily re-trigger garbage collection if no inputs have changed

Author: Veykril

crates/rust-analyzer/src/global_state.rs

@@ -15,7 +15,7 @@ use hir::ChangeWithProcMacros;
 use ide::{Analysis, AnalysisHost, Cancellable, FileId, SourceRootId};
 use ide_db::{
     MiniCore,
-    base_db::{Crate, ProcMacroPaths, SourceDatabase},
+    base_db::{Crate, ProcMacroPaths, SourceDatabase, salsa::Revision},
 };
 use itertools::Itertools;
 use load_cargo::SourceRootConfig;
@@ -194,12 +194,13 @@ pub(crate) struct GlobalState {
     pub(crate) incomplete_crate_graph: bool,
 
     pub(crate) minicore: MiniCoreRustAnalyzerInternalOnly,
+    pub(crate) last_gc_revision: Revision,
 }
 
 // FIXME: This should move to the VFS once the rewrite is done.
 #[derive(Debug, Clone, Default)]
 pub(crate) struct MiniCoreRustAnalyzerInternalOnly {
-    pub(crate) minicore_text: Option<String>,
+    pub(crate) minicore_text: Option<Arc<str>>,
 }
 
 /// An immutable snapshot of the world's state at a point in time.
@@ -256,6 +257,8 @@ impl GlobalState {
 
         let (discover_sender, discover_receiver) = unbounded();
 
+        let last_gc_revision = analysis_host.raw_database().nonce_and_revision().1;
+
         let mut this = GlobalState {
             sender,
             req_queue: ReqQueue::default(),
@@ -319,6 +322,7 @@ impl GlobalState {
             incomplete_crate_graph: false,
 
             minicore: MiniCoreRustAnalyzerInternalOnly::default(),
+            last_gc_revision,
         };
         // Apply any required database inputs from the config.
         this.update_configuration(config);

crates/rust-analyzer/src/main_loop.rs

@@ -536,9 +536,14 @@ impl GlobalState {
                 self.update_tests();
             }
 
+            let current_revision = self.analysis_host.raw_database().nonce_and_revision().1;
             // no work is currently being done, now we can block a bit and clean up our garbage
-            if self.task_pool.handle.is_empty() && self.fmt_pool.handle.is_empty() {
+            if self.task_pool.handle.is_empty()
+                && self.fmt_pool.handle.is_empty()
+                && current_revision != self.last_gc_revision
+            {
                 self.analysis_host.trigger_garbage_collection();
+                self.last_gc_revision = current_revision;
             }
         }
 
@@ -912,7 +917,8 @@ impl GlobalState {
                         // Not a lot of bad can happen from mistakenly identifying `minicore`, so proceed with that.
                         self.minicore.minicore_text = contents
                             .as_ref()
-                            .and_then(|contents| String::from_utf8(contents.clone()).ok());
+                            .and_then(|contents| str::from_utf8(contents).ok())
+                            .map(triomphe::Arc::from);
                     }
 
                     let path = VfsPath::from(path);