Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 123 insertions, 0 deletions

diff --git a/js/src/gc/ParallelMarking.h b/js/src/gc/ParallelMarking.h
new file mode 100644
index 0000000000..46d8f381c6
--- /dev/null
+++ b/js/src/gc/ParallelMarking.h
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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 http://mozilla.org/MPL/2.0/. */
+
+#ifndef gc_ParallelMarking_h
+#define gc_ParallelMarking_h
+
+#include "mozilla/Atomics.h"
+#include "mozilla/DoublyLinkedList.h"
+#include "mozilla/TimeStamp.h"
+
+#include "gc/GCMarker.h"
+#include "gc/GCParallelTask.h"
+#include "js/HeapAPI.h"
+#include "js/SliceBudget.h"
+#include "threading/ConditionVariable.h"
+#include "threading/ProtectedData.h"
+
+namespace js {
+
+class AutoLockGC;
+class AutoLockHelperThreadState;
+class AutoUnlockGC;
+
+namespace gc {
+
+class ParallelMarkTask;
+
+// Per-runtime parallel marking state.
+//
+// This class is used on the main thread and coordinates parallel marking using
+// several helper threads running ParallelMarkTasks.
+//
+// This uses a work-requesting approach. Threads mark until they run out of
+// work and then add themselves to a list of waiting tasks and block. Running
+// tasks with enough work may donate work to a waiting task and resume it.
+class MOZ_STACK_CLASS ParallelMarker {
+ public:
+  explicit ParallelMarker(GCRuntime* gc);
+
+  bool mark(SliceBudget& sliceBudget);
+
+  using AtomicCount = mozilla::Atomic<uint32_t, mozilla::Relaxed>;
+  AtomicCount& waitingTaskCountRef() { return waitingTaskCount; }
+  bool hasWaitingTasks() { return waitingTaskCount != 0; }
+  void donateWorkFrom(GCMarker* src);
+
+ private:
+  bool markOneColor(MarkColor color, SliceBudget& sliceBudget);
+
+  bool hasWork(MarkColor color) const;
+
+  void addTask(ParallelMarkTask* task, const AutoLockGC& lock);
+
+  void addTaskToWaitingList(ParallelMarkTask* task, const AutoLockGC& lock);
+#ifdef DEBUG
+  bool isTaskInWaitingList(const ParallelMarkTask* task,
+                           const AutoLockGC& lock) const;
+#endif
+
+  bool hasActiveTasks(const AutoLockGC& lock) const { return activeTasks; }
+  void incActiveTasks(ParallelMarkTask* task, const AutoLockGC& lock);
+  void decActiveTasks(ParallelMarkTask* task, const AutoLockGC& lock);
+
+  size_t workerCount() const;
+
+  friend class ParallelMarkTask;
+
+  GCRuntime* const gc;
+
+  using ParallelMarkTaskList = mozilla::DoublyLinkedList<ParallelMarkTask>;
+  GCLockData<ParallelMarkTaskList> waitingTasks;
+  AtomicCount waitingTaskCount;
+
+  GCLockData<size_t> activeTasks;
+};
+
+// A helper thread task that performs parallel marking.
+class alignas(TypicalCacheLineSize) ParallelMarkTask
+    : public GCParallelTask,
+      public mozilla::DoublyLinkedListElement<ParallelMarkTask> {
+ public:
+  friend class ParallelMarker;
+
+  ParallelMarkTask(ParallelMarker* pm, GCMarker* marker, MarkColor color,
+                   const SliceBudget& budget);
+  ~ParallelMarkTask();
+
+  void run(AutoLockHelperThreadState& lock) override;
+
+  void recordDuration() override;
+
+ private:
+  void markOrRequestWork(AutoLockGC& lock);
+  bool tryMarking(AutoLockGC& lock);
+  bool requestWork(AutoLockGC& lock);
+
+  void waitUntilResumed(AutoLockGC& lock);
+  void resume();
+  void resumeOnFinish(const AutoLockGC& lock);
+
+  bool hasWork() const;
+
+  // The following fields are only accessed by the marker thread:
+  ParallelMarker* const pm;
+  GCMarker* const marker;
+  AutoSetMarkColor color;
+  SliceBudget budget;
+  ConditionVariable resumed;
+
+  GCLockData<bool> isWaiting;
+
+  // Length of time this task spent blocked waiting for work.
+  MainThreadOrGCTaskData<mozilla::TimeDuration> markTime;
+  MainThreadOrGCTaskData<mozilla::TimeDuration> waitTime;
+};
+
+}  // namespace gc
+}  // namespace js
+
+#endif /* gc_ParallelMarking_h */