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perf: Prime trait impls in cache priming #21087

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Nov 21, 2025
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perf: Prime trait impls in cache priming #21087

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166 changes: 104 additions & 62 deletions crates/ide-db/src/prime_caches.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,7 @@ pub fn parallel_prime_caches(
BeginCrateDefMap { crate_id: Crate, crate_name: Symbol },
EndCrateDefMap { crate_id: Crate },
EndCrateImportMap,
EndSema,
EndModuleSymbols,
Cancelled(Cancelled),
}
Expand Down Expand Up @@ -70,84 +71,113 @@ pub fn parallel_prime_caches(
(reverse_deps, to_be_done_deps)
};

let (def_map_work_sender, import_map_work_sender, symbols_work_sender, progress_receiver) = {
let (
def_map_work_sender,
import_map_work_sender,
symbols_work_sender,
sema_work_sender,
progress_receiver,
) = {
let (progress_sender, progress_receiver) = crossbeam_channel::unbounded();
let (def_map_work_sender, def_map_work_receiver) = crossbeam_channel::unbounded();
let (import_map_work_sender, import_map_work_receiver) = crossbeam_channel::unbounded();
let (sema_work_sender, sema_work_receiver) = crossbeam_channel::unbounded();
let (symbols_work_sender, symbols_work_receiver) = crossbeam_channel::unbounded();
let prime_caches_worker =
move |db: RootDatabase| {
let handle_def_map = |crate_id, crate_name| {
progress_sender.send(ParallelPrimeCacheWorkerProgress::BeginCrateDefMap {
crate_id,
crate_name,
})?;

let cancelled = Cancelled::catch(|| {
_ = hir::crate_def_map(&db, crate_id);
let prime_caches_worker = move |db: RootDatabase| {
let handle_def_map = |crate_id, crate_name| {
progress_sender.send(ParallelPrimeCacheWorkerProgress::BeginCrateDefMap {
crate_id,
crate_name,
})?;

let cancelled = Cancelled::catch(|| {
_ = hir::crate_def_map(&db, crate_id);
});

match cancelled {
Ok(()) => progress_sender
.send(ParallelPrimeCacheWorkerProgress::EndCrateDefMap { crate_id })?,
Err(cancelled) => progress_sender
.send(ParallelPrimeCacheWorkerProgress::Cancelled(cancelled))?,
}

Ok::<_, crossbeam_channel::SendError<_>>(())
};
let handle_sema = |crate_id| {
let cancelled = Cancelled::catch(|| {
hir::attach_db(&db, || {
// method resolution is likely to hit all trait impls at some point
// we pre-populate it here as this will hit a lot of parses ...
_ = hir::TraitImpls::for_crate(&db, crate_id);
// we compute the lang items here as the work for them is also highly recursive and will be trigger by the module symbols query
// slowing down leaf crate analysis tremendously as we go back to being blocked on a single thread
_ = hir::crate_lang_items(&db, crate_id);
});

match cancelled {
Ok(()) => progress_sender
.send(ParallelPrimeCacheWorkerProgress::EndCrateDefMap { crate_id })?,
Err(cancelled) => progress_sender
.send(ParallelPrimeCacheWorkerProgress::Cancelled(cancelled))?,
}
})
});

Ok::<_, crossbeam_channel::SendError<_>>(())
};
let handle_import_map = |crate_id| {
let cancelled = Cancelled::catch(|| _ = db.import_map(crate_id));
match cancelled {
Ok(()) => progress_sender.send(ParallelPrimeCacheWorkerProgress::EndSema)?,
Err(cancelled) => progress_sender
.send(ParallelPrimeCacheWorkerProgress::Cancelled(cancelled))?,
}

match cancelled {
Ok(()) => progress_sender
.send(ParallelPrimeCacheWorkerProgress::EndCrateImportMap)?,
Err(cancelled) => progress_sender
.send(ParallelPrimeCacheWorkerProgress::Cancelled(cancelled))?,
}
Ok::<_, crossbeam_channel::SendError<_>>(())
};
let handle_import_map = |crate_id| {
let cancelled = Cancelled::catch(|| _ = db.import_map(crate_id));

Ok::<_, crossbeam_channel::SendError<_>>(())
};
let handle_symbols = |module| {
let cancelled = Cancelled::catch(AssertUnwindSafe(|| {
_ = SymbolIndex::module_symbols(&db, module)
}));

match cancelled {
Ok(()) => progress_sender
.send(ParallelPrimeCacheWorkerProgress::EndModuleSymbols)?,
Err(cancelled) => progress_sender
.send(ParallelPrimeCacheWorkerProgress::Cancelled(cancelled))?,
match cancelled {
Ok(()) => {
progress_sender.send(ParallelPrimeCacheWorkerProgress::EndCrateImportMap)?
}
Err(cancelled) => progress_sender
.send(ParallelPrimeCacheWorkerProgress::Cancelled(cancelled))?,
}

Ok::<_, crossbeam_channel::SendError<_>>(())
};

loop {
db.unwind_if_revision_cancelled();

// Biased because we want to prefer def maps.
crossbeam_channel::select_biased! {
recv(def_map_work_receiver) -> work => {
let Ok((crate_id, crate_name)) = work else { break };
handle_def_map(crate_id, crate_name)?;
}
recv(import_map_work_receiver) -> work => {
let Ok(crate_id) = work else { break };
handle_import_map(crate_id)?;
}
recv(symbols_work_receiver) -> work => {
let Ok(module) = work else { break };
handle_symbols(module)?;
}
Ok::<_, crossbeam_channel::SendError<_>>(())
};
let handle_symbols = |module: hir::Module| {
let cancelled = Cancelled::catch(AssertUnwindSafe(|| {
_ = SymbolIndex::module_symbols(&db, module)
}));

match cancelled {
Ok(()) => {
progress_sender.send(ParallelPrimeCacheWorkerProgress::EndModuleSymbols)?
}
Err(cancelled) => progress_sender
.send(ParallelPrimeCacheWorkerProgress::Cancelled(cancelled))?,
}

Ok::<_, crossbeam_channel::SendError<_>>(())
};

loop {
db.unwind_if_revision_cancelled();

// Biased because we want to prefer def maps.
crossbeam_channel::select_biased! {
recv(def_map_work_receiver) -> work => {
let Ok((crate_id, crate_name)) = work else { break };
handle_def_map(crate_id, crate_name)?;
}
recv(sema_work_receiver) -> work => {
let Ok(crate_id) = work else { break };
handle_sema(crate_id)?;
}
recv(import_map_work_receiver) -> work => {
let Ok(crate_id) = work else { break };
handle_import_map(crate_id)?;
}
recv(symbols_work_receiver) -> work => {
let Ok(module) = work else { break };
handle_symbols(module)?;
}
}
}
Ok::<_, crossbeam_channel::SendError<_>>(())
};

for id in 0..num_worker_threads {
stdx::thread::Builder::new(
stdx::thread::ThreadIntent::Worker,
Expand All @@ -162,13 +192,20 @@ pub fn parallel_prime_caches(
.expect("failed to spawn thread");
}

(def_map_work_sender, import_map_work_sender, symbols_work_sender, progress_receiver)
(
def_map_work_sender,
import_map_work_sender,
symbols_work_sender,
sema_work_sender,
progress_receiver,
)
};

let crate_def_maps_total = db.all_crates().len();
let mut crate_def_maps_done = 0;
let (mut crate_import_maps_total, mut crate_import_maps_done) = (0usize, 0usize);
let (mut module_symbols_total, mut module_symbols_done) = (0usize, 0usize);
let (mut sema_total, mut sema_done) = (0usize, 0usize);

// an index map is used to preserve ordering so we can sort the progress report in order of
// "longest crate to index" first
Expand All @@ -187,6 +224,7 @@ pub fn parallel_prime_caches(
while crate_def_maps_done < crate_def_maps_total
|| crate_import_maps_done < crate_import_maps_total
|| module_symbols_done < module_symbols_total
|| sema_done < sema_total
{
db.unwind_if_revision_cancelled();

Expand Down Expand Up @@ -233,6 +271,7 @@ pub fn parallel_prime_caches(
}

if crate_def_maps_done == crate_def_maps_total {
// Can we trigger lru-eviction once at this point to reduce peak memory usage?
cb(ParallelPrimeCachesProgress {
crates_currently_indexing: vec![],
crates_done: crate_def_maps_done,
Expand All @@ -241,6 +280,8 @@ pub fn parallel_prime_caches(
});
}

sema_work_sender.send(crate_id).ok();
sema_total += 1;
let origin = &crate_id.data(db).origin;
if origin.is_lang() {
crate_import_maps_total += 1;
Expand All @@ -264,6 +305,7 @@ pub fn parallel_prime_caches(
}
ParallelPrimeCacheWorkerProgress::EndCrateImportMap => crate_import_maps_done += 1,
ParallelPrimeCacheWorkerProgress::EndModuleSymbols => module_symbols_done += 1,
ParallelPrimeCacheWorkerProgress::EndSema => sema_done += 1,
ParallelPrimeCacheWorkerProgress::Cancelled(cancelled) => {
// Cancelled::throw should probably be public
std::panic::resume_unwind(Box::new(cancelled));
Expand Down