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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
* API for managing off-thread work.
#ifndef vm_HelperThreads_h
#define vm_HelperThreads_h
#include "mozilla/Variant.h"
#include "js/AllocPolicy.h"
#include "js/shadow/Zone.h"
#include "js/UniquePtr.h"
#include "js/Vector.h"
#include "threading/LockGuard.h"
#include "threading/Mutex.h"
#include "wasm/WasmConstants.h"
namespace mozilla {
union Utf8Unit;
namespace JS {
class JS_PUBLIC_API ReadOnlyCompileOptions;
class JS_PUBLIC_API ReadOnlyDecodeOptions;
class Zone;
template <typename UnitT>
class SourceText;
} // namespace JS
namespace js {
class AutoLockHelperThreadState;
struct PromiseHelperTask;
class SourceCompressionTask;
namespace frontend {
struct CompilationStencil;
namespace gc {
class GCRuntime;
namespace jit {
class IonCompileTask;
class IonFreeTask;
class JitRuntime;
using IonFreeCompileTasks = Vector<IonCompileTask*, 8, SystemAllocPolicy>;
} // namespace jit
namespace wasm {
struct CompileTask;
struct CompileTaskState;
struct Tier2GeneratorTask;
using UniqueTier2GeneratorTask = UniquePtr<Tier2GeneratorTask>;
} // namespace wasm
* Lock protecting all mutable shared state accessed by helper threads, and used
* by all condition variables.
extern Mutex gHelperThreadLock MOZ_UNANNOTATED;
class MOZ_RAII AutoLockHelperThreadState : public LockGuard<Mutex> {
using Base = LockGuard<Mutex>;
explicit AutoLockHelperThreadState() : Base(gHelperThreadLock) {}
class MOZ_RAII AutoUnlockHelperThreadState : public UnlockGuard<Mutex> {
using Base = UnlockGuard<Mutex>;
explicit AutoUnlockHelperThreadState(AutoLockHelperThreadState& locked)
: Base(locked) {}
// Create data structures used by helper threads.
bool CreateHelperThreadsState();
// Destroy data structures used by helper threads.
void DestroyHelperThreadsState();
// Initialize helper threads unless already initialized.
bool EnsureHelperThreadsInitialized();
size_t GetHelperThreadCount();
size_t GetHelperThreadCPUCount();
size_t GetMaxWasmCompilationThreads();
// This allows the JS shell to override GetCPUCount() when passed the
// --thread-count=N option.
bool SetFakeCPUCount(size_t count);
// Enqueues a wasm compilation task.
bool StartOffThreadWasmCompile(wasm::CompileTask* task, wasm::CompileMode mode);
// Remove any pending wasm compilation tasks queued with
// StartOffThreadWasmCompile that match the arguments. Return the number
// removed.
size_t RemovePendingWasmCompileTasks(const wasm::CompileTaskState& taskState,
wasm::CompileMode mode,
const AutoLockHelperThreadState& lock);
// Enqueues a wasm compilation task.
void StartOffThreadWasmTier2Generator(wasm::UniqueTier2GeneratorTask task);
// Cancel all background Wasm Tier-2 compilations.
void CancelOffThreadWasmTier2Generator();
* If helper threads are available, call execute() then dispatchResolve() on the
* given task in a helper thread. If no helper threads are available, the given
* task is executed and resolved synchronously.
* This function takes ownership of task unconditionally; if it fails, task is
* deleted.
bool StartOffThreadPromiseHelperTask(JSContext* cx,
UniquePtr<PromiseHelperTask> task);
* Like the JSContext-accepting version, but only safe to use when helper
* threads are available, so we can be sure we'll never need to fall back on
* synchronous execution.
* This function can be called from any thread, but takes ownership of the task
* only on success. On OOM, it is the caller's responsibility to arrange for the
* task to be cleaned up properly.
bool StartOffThreadPromiseHelperTask(PromiseHelperTask* task);
* Schedule an off-thread Ion compilation for a script, given a task.
bool StartOffThreadIonCompile(jit::IonCompileTask* task,
const AutoLockHelperThreadState& lock);
void FinishOffThreadIonCompile(jit::IonCompileTask* task,
const AutoLockHelperThreadState& lock);
// RAII class to handle batching compile tasks and starting an IonFreeTask.
class MOZ_RAII AutoStartIonFreeTask {
jit::JitRuntime* jitRuntime_;
// If true, start an IonFreeTask even if the batch is small.
bool force_;
explicit AutoStartIonFreeTask(jit::JitRuntime* jitRuntime, bool force = false)
: jitRuntime_(jitRuntime), force_(force) {}
[[nodiscard]] bool addIonCompileToFreeTaskBatch(jit::IonCompileTask* task);
struct ZonesInState {
JSRuntime* runtime;
JS::shadow::Zone::GCState state;
using CompilationSelector =
mozilla::Variant<JSScript*, JS::Zone*, ZonesInState, JSRuntime*>;
* Cancel scheduled or in progress Ion compilations.
void CancelOffThreadIonCompile(const CompilationSelector& selector);
inline void CancelOffThreadIonCompile(JSScript* script) {
inline void CancelOffThreadIonCompile(JS::Zone* zone) {
inline void CancelOffThreadIonCompile(JSRuntime* runtime,
JS::shadow::Zone::GCState state) {
CancelOffThreadIonCompile(CompilationSelector(ZonesInState{runtime, state}));
inline void CancelOffThreadIonCompile(JSRuntime* runtime) {
#ifdef DEBUG
bool HasOffThreadIonCompile(JS::Zone* zone);
* Cancel all scheduled or in progress eager delazification phases for a
* runtime.
void CancelOffThreadDelazify(JSRuntime* runtime);
* Wait for all delazification to complete.
void WaitForAllDelazifyTasks(JSRuntime* rt);
// Start off-thread delazification task, to race the delazification of inner
// functions.
void StartOffThreadDelazification(JSContext* maybeCx,
const JS::ReadOnlyCompileOptions& options,
const frontend::CompilationStencil& stencil);
// Drain the task queues and wait for all helper threads to finish running.
// Note that helper threads are shared between runtimes and it's possible that
// another runtime could saturate the helper thread system and cause this to
// never return.
void WaitForAllHelperThreads();
void WaitForAllHelperThreads(AutoLockHelperThreadState& lock);
// Enqueue a compression job to be processed later. These are started at the
// start of the major GC after the next one.
bool EnqueueOffThreadCompression(JSContext* cx,
UniquePtr<SourceCompressionTask> task);
// Start handling any compression tasks for this runtime. Called at the start of
// major GC.
void StartHandlingCompressionsOnGC(JSRuntime* rt);
// Cancel all scheduled, in progress, or finished compression tasks for
// runtime.
void CancelOffThreadCompressions(JSRuntime* runtime);
void AttachFinishedCompressions(JSRuntime* runtime,
AutoLockHelperThreadState& lock);
// Sweep pending tasks that are holding onto should-be-dead ScriptSources.
void SweepPendingCompressions(AutoLockHelperThreadState& lock);
// Run all pending source compression tasks synchronously, for testing purposes
void RunPendingSourceCompressions(JSRuntime* runtime);
// False if the off-thread source compression mechanism isn't being used. This
// happens on low core count machines where we are concerned about blocking
// main-thread execution.
bool IsOffThreadSourceCompressionEnabled();
} // namespace js
#endif /* vm_HelperThreads_h */