Merge #9206

9206: minor: Speed up fst items lookup during completions r=SomeoneToIgnore a=SomeoneToIgnore

Part of https://github.com/rust-analyzer/rust-analyzer/issues/7542

A number of profile calls added for `import_on_the_fly` contents.
Before:
<img width="606" alt="Screenshot 2021-06-11 at 00 19 13" src="https://user-images.githubusercontent.com/2690773/121598998-22321e80-ca4b-11eb-9a3d-dc9cb2936705.png">

After:
<img width="859" alt="Screenshot 2021-06-11 at 00 19 27" src="https://user-images.githubusercontent.com/2690773/121599022-2a8a5980-ca4b-11eb-82b6-13ab0ed56d58.png">

As a result, low hanging fruit was spotted: crazy amount of `fst_path` calls. Reducing that won ~200ms in the `import_on_the_fly @ sel` case in the `integrated_completion_benchmark`:

<img width="861" alt="Screenshot 2021-06-11 at 00 19 38" src="https://user-images.githubusercontent.com/2690773/121599277-7d641100-ca4b-11eb-8667-53206994de27.png">

I'm not sure how to proceed with the remaining `???` marks in such methods as `collect_import_map` though: there's nothing but library calls in cycles, but maybe I'll come up with something later.

Co-authored-by: Kirill Bulatov <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/crates/ide_db/src/symbol_index.rs b/crates/ide_db/src/symbol_index.rs
index 5c372a7e5..000f87a85 100644
--- a/crates/ide_db/src/symbol_index.rs
+++ b/crates/ide_db/src/symbol_index.rs
@@ -197,6 +197,7 @@ pub fn world_symbols(db: &RootDatabase, query: Query) -> Vec<FileSymbol> {
 }
 
 pub fn crate_symbols(db: &RootDatabase, krate: CrateId, query: Query) -> Vec<FileSymbol> {
+    let _p = profile::span("crate_symbols").detail(|| format!("{:?}", query));
     // FIXME(#4842): This now depends on CrateDefMap, why not build the entire symbol index from
     // that instead?
 
@@ -321,6 +322,7 @@ impl SymbolIndex {
 
 impl Query {
     pub(crate) fn search(self, indices: &[&SymbolIndex]) -> Vec<FileSymbol> {
+        let _p = profile::span("symbol_index::Query::search");
         let mut op = fst::map::OpBuilder::new();
         for file_symbols in indices.iter() {
             let automaton = fst::automaton::Subsequence::new(&self.lowercased);