1 files changed, 173 insertions, 0 deletions
diff --git a/js/src/gc/GCParallelTask.cpp b/js/src/gc/GCParallelTask.cpp
new file mode 100644
index 0000000000..8162e33000
--- /dev/null
+++ b/js/src/gc/GCParallelTask.cpp
@@ -0,0 +1,173 @@
+/* -*- 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 http://mozilla.org/MPL/2.0/. */
+
+#include "gc/GCParallelTask.h"
+
+#include "mozilla/MathAlgorithms.h"
+
+#include "gc/ParallelWork.h"
+#include "vm/HelperThreadState.h"
+#include "vm/Runtime.h"
+#include "vm/TraceLogging.h"
+
+using namespace js;
+using namespace js::gc;
+
+using mozilla::TimeDuration;
+using mozilla::TimeStamp;
+
+js::GCParallelTask::~GCParallelTask() {
+  // Only most-derived classes' destructors may do the join: base class
+  // destructors run after those for derived classes' members, so a join in a
+  // base class can't ensure that the task is done using the members. All we
+  // can do now is check that someone has previously stopped the task.
+  assertIdle();
+}
+
+void js::GCParallelTask::startWithLockHeld(AutoLockHelperThreadState& lock) {
+  MOZ_ASSERT(CanUseExtraThreads());
+  MOZ_ASSERT(!HelperThreadState().threads(lock).empty());
+  assertIdle();
+
+  setDispatched(lock);
+  HelperThreadState().submitTask(this, lock);
+}
+
+void js::GCParallelTask::start() {
+  if (!CanUseExtraThreads()) {
+    runFromMainThread();
+    return;
+  }
+
+  AutoLockHelperThreadState lock;
+  startWithLockHeld(lock);
+}
+
+void js::GCParallelTask::startOrRunIfIdle(AutoLockHelperThreadState& lock) {
+  if (wasStarted(lock)) {
+    return;
+  }
+
+  // Join the previous invocation of the task. This will return immediately
+  // if the thread has never been started.
+  joinWithLockHeld(lock);
+
+  if (!CanUseExtraThreads()) {
+    AutoUnlockHelperThreadState unlock(lock);
+    runFromMainThread();
+    return;
+  }
+
+  startWithLockHeld(lock);
+}
+
+void js::GCParallelTask::cancelAndWait() {
+  MOZ_ASSERT(!isCancelled());
+  cancel_ = true;
+  join();
+  cancel_ = false;
+}
+
+void js::GCParallelTask::join() {
+  AutoLockHelperThreadState lock;
+  joinWithLockHeld(lock);
+}
+
+void js::GCParallelTask::joinWithLockHeld(AutoLockHelperThreadState& lock) {
+  // Task has not been started; there's nothing to do.
+  if (isIdle(lock)) {
+    return;
+  }
+
+  // If the task was dispatched but has not yet started then cancel the task and
+  // run it from the main thread. This stops us from blocking here when the
+  // helper threads are busy with other tasks.
+  if (isDispatched(lock)) {
+    cancelDispatchedTask(lock);
+    AutoUnlockHelperThreadState unlock(lock);
+    runFromMainThread();
+    return;
+  }
+
+  joinRunningOrFinishedTask(lock);
+}
+
+void js::GCParallelTask::joinRunningOrFinishedTask(
+    AutoLockHelperThreadState& lock) {
+  MOZ_ASSERT(isRunning(lock) || isFinished(lock));
+
+  // Wait for the task to run to completion.
+  while (!isFinished(lock)) {
+    HelperThreadState().wait(lock, GlobalHelperThreadState::CONSUMER);
+  }
+
+  setIdle(lock);
+}
+
+void js::GCParallelTask::cancelDispatchedTask(AutoLockHelperThreadState& lock) {
+  MOZ_ASSERT(isDispatched(lock));
+  MOZ_ASSERT(isInList());
+  remove();
+  setIdle(lock);
+}
+
+static inline TimeDuration TimeSince(TimeStamp prev) {
+  TimeStamp now = ReallyNow();
+  // Sadly this happens sometimes.
+  MOZ_ASSERT(now >= prev);
+  if (now < prev) {
+    now = prev;
+  }
+  return now - prev;
+}
+
+void js::GCParallelTask::runFromMainThread() {
+  assertIdle();
+  MOZ_ASSERT(js::CurrentThreadCanAccessRuntime(gc->rt));
+  AutoLockHelperThreadState lock;
+  runTask(lock);
+}
+
+void js::GCParallelTask::runHelperThreadTask(AutoLockHelperThreadState& lock) {
+  TraceLoggerThread* logger = TraceLoggerForCurrentThread();
+  AutoTraceLog logCompile(logger, TraceLogger_GC);
+
+  setRunning(lock);
+
+  AutoSetHelperThreadContext usesContext(lock);
+  AutoSetContextRuntime ascr(gc->rt);
+  gc::AutoSetThreadIsPerformingGC performingGC;
+  runTask(lock);
+
+  setFinished(lock);
+}
+
+void GCParallelTask::runTask(AutoLockHelperThreadState& lock) {
+  // Run the task from either the main thread or a helper thread.
+
+  // The hazard analysis can't tell what the call to func_ will do but it's not
+  // allowed to GC.
+  JS::AutoSuppressGCAnalysis nogc;
+
+  TimeStamp timeStart = ReallyNow();
+  run(lock);
+  duration_ = TimeSince(timeStart);
+}
+
+bool js::GCParallelTask::isIdle() const {
+  AutoLockHelperThreadState lock;
+  return isIdle(lock);
+}
+
+bool js::GCParallelTask::wasStarted() const {
+  AutoLockHelperThreadState lock;
+  return wasStarted(lock);
+}
+
+/* static */
+size_t js::gc::GCRuntime::parallelWorkerCount() const {
+  return std::min(helperThreadCount.ref(), MaxParallelWorkers);
+}