ide_db/
prime_caches.rs

1//! rust-analyzer is lazy and doesn't compute anything unless asked. This
2//! sometimes is counter productive when, for example, the first goto definition
3//! request takes longer to compute. This module implements prepopulation of
4//! various caches, it's not really advanced at the moment.
5use std::panic::AssertUnwindSafe;
6
7use hir::{Symbol, db::DefDatabase};
8use rustc_hash::FxHashMap;
9use salsa::{Cancelled, Database};
10
11use crate::{
12    FxIndexMap, RootDatabase,
13    base_db::{Crate, RootQueryDb},
14    symbol_index::SymbolIndex,
15};
16
17/// We're indexing many crates.
18#[derive(Debug)]
19pub struct ParallelPrimeCachesProgress {
20    /// the crates that we are currently priming.
21    pub crates_currently_indexing: Vec<Symbol>,
22    /// the total number of crates we want to prime.
23    pub crates_total: usize,
24    /// the total number of crates that have finished priming
25    pub crates_done: usize,
26    pub work_type: &'static str,
27}
28
29pub fn parallel_prime_caches(
30    db: &RootDatabase,
31    num_worker_threads: usize,
32    cb: &(dyn Fn(ParallelPrimeCachesProgress) + Sync),
33) {
34    let _p = tracing::info_span!("parallel_prime_caches").entered();
35
36    enum ParallelPrimeCacheWorkerProgress {
37        BeginCrateDefMap { crate_id: Crate, crate_name: Symbol },
38        EndCrateDefMap { crate_id: Crate },
39        EndCrateImportMap,
40        EndSema,
41        EndModuleSymbols,
42        Cancelled(Cancelled),
43    }
44
45    // The setup here is a bit complicated. We try to make best use of compute resources.
46    // The idea is that if we have a def map available to compute, we should do that first.
47    // This is because def map is a dependency of both import map and symbols. So if we have
48    // e.g. a def map and a symbols, if we compute the def map we can, after it completes,
49    // compute the def maps of dependencies, the existing symbols and the symbols of the
50    // new crate, all in parallel. But if we compute the symbols, after that we will only
51    // have the def map to compute, and the rest of the CPU cores will rest, which is not
52    // good.
53    // However, it's better to compute symbols/import map than to compute a def map that
54    // isn't ready yet, because one of its dependencies hasn't yet completed its def map.
55    // Such def map will just block on the dependency, which is just wasted time. So better
56    // to compute the symbols/import map of an already computed def map in that time.
57
58    let (reverse_deps, mut to_be_done_deps) = {
59        let all_crates = db.all_crates();
60        let to_be_done_deps = all_crates
61            .iter()
62            .map(|&krate| (krate, krate.data(db).dependencies.len() as u32))
63            .collect::<FxHashMap<_, _>>();
64        let mut reverse_deps =
65            all_crates.iter().map(|&krate| (krate, Vec::new())).collect::<FxHashMap<_, _>>();
66        for &krate in &*all_crates {
67            for dep in &krate.data(db).dependencies {
68                reverse_deps.get_mut(&dep.crate_id).unwrap().push(krate);
69            }
70        }
71        (reverse_deps, to_be_done_deps)
72    };
73
74    let (
75        def_map_work_sender,
76        import_map_work_sender,
77        symbols_work_sender,
78        sema_work_sender,
79        progress_receiver,
80    ) = {
81        let (progress_sender, progress_receiver) = crossbeam_channel::unbounded();
82        let (def_map_work_sender, def_map_work_receiver) = crossbeam_channel::unbounded();
83        let (import_map_work_sender, import_map_work_receiver) = crossbeam_channel::unbounded();
84        let (sema_work_sender, sema_work_receiver) = crossbeam_channel::unbounded();
85        let (symbols_work_sender, symbols_work_receiver) = crossbeam_channel::unbounded();
86        let prime_caches_worker = move |db: RootDatabase| {
87            let handle_def_map = |crate_id, crate_name| {
88                progress_sender.send(ParallelPrimeCacheWorkerProgress::BeginCrateDefMap {
89                    crate_id,
90                    crate_name,
91                })?;
92
93                let cancelled = Cancelled::catch(|| {
94                    _ = hir::crate_def_map(&db, crate_id);
95                });
96
97                match cancelled {
98                    Ok(()) => progress_sender
99                        .send(ParallelPrimeCacheWorkerProgress::EndCrateDefMap { crate_id })?,
100                    Err(cancelled) => progress_sender
101                        .send(ParallelPrimeCacheWorkerProgress::Cancelled(cancelled))?,
102                }
103
104                Ok::<_, crossbeam_channel::SendError<_>>(())
105            };
106            let handle_sema = |crate_id| {
107                let cancelled = Cancelled::catch(|| {
108                    hir::attach_db(&db, || {
109                        // method resolution is likely to hit all trait impls at some point
110                        // we pre-populate it here as this will hit a lot of parses ...
111                        // This also computes the lang items, which is what we want as the work for them is also highly recursive and will be trigger by the module symbols query
112                        // slowing down leaf crate analysis tremendously as we go back to being blocked on a single thread
113                        _ = hir::TraitImpls::for_crate(&db, crate_id);
114                    })
115                });
116
117                match cancelled {
118                    Ok(()) => progress_sender.send(ParallelPrimeCacheWorkerProgress::EndSema)?,
119                    Err(cancelled) => progress_sender
120                        .send(ParallelPrimeCacheWorkerProgress::Cancelled(cancelled))?,
121                }
122
123                Ok::<_, crossbeam_channel::SendError<_>>(())
124            };
125            let handle_import_map = |crate_id| {
126                let cancelled = Cancelled::catch(|| _ = db.import_map(crate_id));
127
128                match cancelled {
129                    Ok(()) => {
130                        progress_sender.send(ParallelPrimeCacheWorkerProgress::EndCrateImportMap)?
131                    }
132                    Err(cancelled) => progress_sender
133                        .send(ParallelPrimeCacheWorkerProgress::Cancelled(cancelled))?,
134                }
135
136                Ok::<_, crossbeam_channel::SendError<_>>(())
137            };
138            let handle_symbols = |module: hir::Module| {
139                let cancelled = Cancelled::catch(AssertUnwindSafe(|| {
140                    _ = SymbolIndex::module_symbols(&db, module)
141                }));
142
143                match cancelled {
144                    Ok(()) => {
145                        progress_sender.send(ParallelPrimeCacheWorkerProgress::EndModuleSymbols)?
146                    }
147                    Err(cancelled) => progress_sender
148                        .send(ParallelPrimeCacheWorkerProgress::Cancelled(cancelled))?,
149                }
150
151                Ok::<_, crossbeam_channel::SendError<_>>(())
152            };
153
154            loop {
155                db.unwind_if_revision_cancelled();
156
157                // Biased because we want to prefer def maps.
158                crossbeam_channel::select_biased! {
159                    recv(def_map_work_receiver) -> work => {
160                        let Ok((crate_id, crate_name)) = work else { break };
161                        handle_def_map(crate_id, crate_name)?;
162                    }
163                    recv(sema_work_receiver) -> work => {
164                        let Ok(crate_id) = work else { break };
165                        handle_sema(crate_id)?;
166                    }
167                    recv(import_map_work_receiver) -> work => {
168                        let Ok(crate_id) = work else { break };
169                        handle_import_map(crate_id)?;
170                    }
171                    recv(symbols_work_receiver) -> work => {
172                        let Ok(module) = work else { break };
173                        handle_symbols(module)?;
174                    }
175                }
176            }
177            Ok::<_, crossbeam_channel::SendError<_>>(())
178        };
179
180        for id in 0..num_worker_threads {
181            stdx::thread::Builder::new(
182                stdx::thread::ThreadIntent::Worker,
183                format!("PrimeCaches#{id}"),
184            )
185            .allow_leak(true)
186            .spawn({
187                let worker = prime_caches_worker.clone();
188                let db = db.clone();
189                move || worker(db)
190            })
191            .expect("failed to spawn thread");
192        }
193
194        (
195            def_map_work_sender,
196            import_map_work_sender,
197            symbols_work_sender,
198            sema_work_sender,
199            progress_receiver,
200        )
201    };
202
203    let crate_def_maps_total = db.all_crates().len();
204    let mut crate_def_maps_done = 0;
205    let (mut crate_import_maps_total, mut crate_import_maps_done) = (0usize, 0usize);
206    let (mut module_symbols_total, mut module_symbols_done) = (0usize, 0usize);
207    let (mut sema_total, mut sema_done) = (0usize, 0usize);
208
209    // an index map is used to preserve ordering so we can sort the progress report in order of
210    // "longest crate to index" first
211    let mut crates_currently_indexing =
212        FxIndexMap::with_capacity_and_hasher(num_worker_threads, Default::default());
213
214    for (&krate, &to_be_done_deps) in &to_be_done_deps {
215        if to_be_done_deps != 0 {
216            continue;
217        }
218
219        let name = crate_name(db, krate);
220        def_map_work_sender.send((krate, name)).ok();
221    }
222
223    while crate_def_maps_done < crate_def_maps_total
224        || crate_import_maps_done < crate_import_maps_total
225        || module_symbols_done < module_symbols_total
226        || sema_done < sema_total
227    {
228        db.unwind_if_revision_cancelled();
229
230        let progress = ParallelPrimeCachesProgress {
231            crates_currently_indexing: crates_currently_indexing.values().cloned().collect(),
232            crates_done: crate_def_maps_done,
233            crates_total: crate_def_maps_total,
234            work_type: "Indexing",
235        };
236
237        cb(progress);
238
239        // Biased to prefer progress updates (and because it's faster).
240        let progress = match progress_receiver.recv() {
241            Ok(p) => p,
242            Err(crossbeam_channel::RecvError) => {
243                // all our workers have exited, mark us as finished and exit
244                cb(ParallelPrimeCachesProgress {
245                    crates_currently_indexing: vec![],
246                    crates_done: crate_def_maps_done,
247                    crates_total: crate_def_maps_done,
248                    work_type: "Done",
249                });
250                return;
251            }
252        };
253
254        match progress {
255            ParallelPrimeCacheWorkerProgress::BeginCrateDefMap { crate_id, crate_name } => {
256                crates_currently_indexing.insert(crate_id, crate_name);
257            }
258            ParallelPrimeCacheWorkerProgress::EndCrateDefMap { crate_id } => {
259                crates_currently_indexing.swap_remove(&crate_id);
260                crate_def_maps_done += 1;
261
262                // Fire ready dependencies.
263                for &dep in &reverse_deps[&crate_id] {
264                    let to_be_done = to_be_done_deps.get_mut(&dep).unwrap();
265                    *to_be_done -= 1;
266                    if *to_be_done == 0 {
267                        let dep_name = crate_name(db, dep);
268                        def_map_work_sender.send((dep, dep_name)).ok();
269                    }
270                }
271
272                if crate_def_maps_done == crate_def_maps_total {
273                    cb(ParallelPrimeCachesProgress {
274                        crates_currently_indexing: vec![],
275                        crates_done: crate_def_maps_done,
276                        crates_total: crate_def_maps_done,
277                        work_type: "Collecting Symbols",
278                    });
279                }
280
281                sema_work_sender.send(crate_id).ok();
282                sema_total += 1;
283                let origin = &crate_id.data(db).origin;
284                if origin.is_lang() {
285                    crate_import_maps_total += 1;
286                    import_map_work_sender.send(crate_id).ok();
287                } else if origin.is_local() {
288                    // Compute the symbol search index.
289                    // This primes the cache for `ide_db::symbol_index::world_symbols()`.
290                    //
291                    // We do this for workspace crates only (members of local_roots), because doing it
292                    // for all dependencies could be *very* unnecessarily slow in a large project.
293                    //
294                    // FIXME: We should do it unconditionally if the configuration is set to default to
295                    // searching dependencies (rust-analyzer.workspace.symbol.search.scope), but we
296                    // would need to pipe that configuration information down here.
297                    let modules = hir::Crate::from(crate_id).modules(db);
298                    module_symbols_total += modules.len();
299                    for module in modules {
300                        symbols_work_sender.send(module).ok();
301                    }
302                }
303            }
304            ParallelPrimeCacheWorkerProgress::EndCrateImportMap => crate_import_maps_done += 1,
305            ParallelPrimeCacheWorkerProgress::EndModuleSymbols => module_symbols_done += 1,
306            ParallelPrimeCacheWorkerProgress::EndSema => sema_done += 1,
307            ParallelPrimeCacheWorkerProgress::Cancelled(cancelled) => {
308                // Cancelled::throw should probably be public
309                std::panic::resume_unwind(Box::new(cancelled));
310            }
311        }
312    }
313}
314
315fn crate_name(db: &RootDatabase, krate: Crate) -> Symbol {
316    krate
317        .extra_data(db)
318        .display_name
319        .as_deref()
320        .cloned()
321        .unwrap_or_else(|| Symbol::integer(salsa::plumbing::AsId::as_id(&krate).index() as usize))
322}
ide_db/prime_caches.rs

ide_db/
prime_caches.rs
