1 files changed, 289 insertions, 0 deletions
diff --git a/js/src/vm/InternalThreadPool.cpp b/js/src/vm/InternalThreadPool.cpp
new file mode 100644
index 0000000000..483e995254
--- /dev/null
+++ b/js/src/vm/InternalThreadPool.cpp
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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/. */
+
+#include "vm/InternalThreadPool.h"
+
+#include "mozilla/TimeStamp.h"
+
+#include "js/ProfilingCategory.h"
+#include "js/ProfilingStack.h"
+#include "threading/Thread.h"
+#include "util/NativeStack.h"
+#include "vm/HelperThreadState.h"
+#include "vm/JSContext.h"
+
+// We want our default stack size limit to be approximately 2MB, to be safe, but
+// expect most threads to use much less. On Linux, however, requesting a stack
+// of 2MB or larger risks the kernel allocating an entire 2MB huge page for it
+// on first access, which we do not want. To avoid this possibility, we subtract
+// 2 standard VM page sizes from our default.
+static const uint32_t kDefaultHelperStackSize = 2048 * 1024 - 2 * 4096;
+
+// TSan enforces a minimum stack size that's just slightly larger than our
+// default helper stack size.  It does this to store blobs of TSan-specific
+// data on each thread's stack.  Unfortunately, that means that even though
+// we'll actually receive a larger stack than we requested, the effective
+// usable space of that stack is significantly less than what we expect.
+// To offset TSan stealing our stack space from underneath us, double the
+// default.
+//
+// Note that we don't need this for ASan/MOZ_ASAN because ASan doesn't
+// require all the thread-specific state that TSan does.
+#if defined(MOZ_TSAN)
+static const uint32_t HELPER_STACK_SIZE = 2 * kDefaultHelperStackSize;
+#else
+static const uint32_t HELPER_STACK_SIZE = kDefaultHelperStackSize;
+#endif
+
+// These macros are identical in function to the same-named ones in
+// GeckoProfiler.h, but they are defined separately because SpiderMonkey can't
+// use GeckoProfiler.h.
+#define PROFILER_RAII_PASTE(id, line) id##line
+#define PROFILER_RAII_EXPAND(id, line) PROFILER_RAII_PASTE(id, line)
+#define PROFILER_RAII PROFILER_RAII_EXPAND(raiiObject, __LINE__)
+#define AUTO_PROFILER_LABEL(label, categoryPair) \
+  HelperThread::AutoProfilerLabel PROFILER_RAII( \
+      this, label, JS::ProfilingCategoryPair::categoryPair)
+
+using namespace js;
+
+namespace js {
+
+class HelperThread {
+  Thread thread;
+
+  /*
+   * The profiling thread for this helper thread, which can be used to push
+   * and pop label frames.
+   * This field being non-null indicates that this thread has been registered
+   * and needs to be unregistered at shutdown.
+   */
+  ProfilingStack* profilingStack = nullptr;
+
+ public:
+  HelperThread();
+  [[nodiscard]] bool init(InternalThreadPool* pool);
+
+  ThreadId threadId() { return thread.get_id(); }
+
+  void join();
+
+  static void ThreadMain(InternalThreadPool* pool, HelperThread* helper);
+  void threadLoop(InternalThreadPool* pool);
+
+  void ensureRegisteredWithProfiler();
+  void unregisterWithProfilerIfNeeded();
+
+ private:
+  struct AutoProfilerLabel {
+    AutoProfilerLabel(HelperThread* helperThread, const char* label,
+                      JS::ProfilingCategoryPair categoryPair);
+    ~AutoProfilerLabel();
+
+   private:
+    ProfilingStack* profilingStack;
+  };
+};
+
+}  // namespace js
+
+InternalThreadPool* InternalThreadPool::Instance = nullptr;
+
+/* static */ InternalThreadPool& InternalThreadPool::Get() {
+  MOZ_ASSERT(IsInitialized());
+  return *Instance;
+}
+
+/* static */
+bool InternalThreadPool::Initialize(size_t threadCount,
+                                    AutoLockHelperThreadState& lock) {
+  if (IsInitialized()) {
+    return true;
+  }
+
+  auto instance = MakeUnique<InternalThreadPool>();
+  if (!instance) {
+    return false;
+  }
+
+  if (!instance->ensureThreadCount(threadCount, lock)) {
+    instance->shutDown(lock);
+    return false;
+  }
+
+  Instance = instance.release();
+  HelperThreadState().setDispatchTaskCallback(DispatchTask, threadCount,
+                                              HELPER_STACK_SIZE, lock);
+  return true;
+}
+
+bool InternalThreadPool::ensureThreadCount(size_t threadCount,
+                                           AutoLockHelperThreadState& lock) {
+  MOZ_ASSERT(threads(lock).length() < threadCount);
+
+  if (!threads(lock).reserve(threadCount)) {
+    return false;
+  }
+
+  while (threads(lock).length() < threadCount) {
+    auto thread = js::MakeUnique<HelperThread>();
+    if (!thread || !thread->init(this)) {
+      return false;
+    }
+
+    threads(lock).infallibleEmplaceBack(std::move(thread));
+  }
+
+  return true;
+}
+
+size_t InternalThreadPool::threadCount(const AutoLockHelperThreadState& lock) {
+  return threads(lock).length();
+}
+
+/* static */
+void InternalThreadPool::ShutDown(AutoLockHelperThreadState& lock) {
+  MOZ_ASSERT(HelperThreadState().isTerminating(lock));
+
+  Get().shutDown(lock);
+  js_delete(Instance);
+  Instance = nullptr;
+}
+
+void InternalThreadPool::shutDown(AutoLockHelperThreadState& lock) {
+  MOZ_ASSERT(!terminating);
+  terminating = true;
+
+  notifyAll(lock);
+
+  for (auto& thread : threads(lock)) {
+    AutoUnlockHelperThreadState unlock(lock);
+    thread->join();
+  }
+}
+
+inline HelperThreadVector& InternalThreadPool::threads(
+    const AutoLockHelperThreadState& lock) {
+  return threads_.ref();
+}
+inline const HelperThreadVector& InternalThreadPool::threads(
+    const AutoLockHelperThreadState& lock) const {
+  return threads_.ref();
+}
+
+size_t InternalThreadPool::sizeOfIncludingThis(
+    mozilla::MallocSizeOf mallocSizeOf,
+    const AutoLockHelperThreadState& lock) const {
+  return sizeof(InternalThreadPool) +
+         threads(lock).sizeOfExcludingThis(mallocSizeOf);
+}
+
+/* static */
+void InternalThreadPool::DispatchTask(JS::DispatchReason reason) {
+  Get().dispatchTask(reason);
+}
+
+void InternalThreadPool::dispatchTask(JS::DispatchReason reason) {
+  gHelperThreadLock.assertOwnedByCurrentThread();
+  queuedTasks++;
+  if (reason == JS::DispatchReason::NewTask) {
+    wakeup.notify_one();
+  } else {
+    // We're called from a helper thread right before returning to
+    // HelperThread::threadLoop. There we will check queuedTasks so there's no
+    // need to wake up any threads.
+    MOZ_ASSERT(reason == JS::DispatchReason::FinishedTask);
+    MOZ_ASSERT(!TlsContext.get(), "we should be on a helper thread");
+  }
+}
+
+void InternalThreadPool::notifyAll(const AutoLockHelperThreadState& lock) {
+  wakeup.notify_all();
+}
+
+void InternalThreadPool::wait(AutoLockHelperThreadState& lock) {
+  wakeup.wait_for(lock, mozilla::TimeDuration::Forever());
+}
+
+HelperThread::HelperThread()
+    : thread(Thread::Options().setStackSize(HELPER_STACK_SIZE)) {}
+
+bool HelperThread::init(InternalThreadPool* pool) {
+  return thread.init(HelperThread::ThreadMain, pool, this);
+}
+
+void HelperThread::join() { thread.join(); }
+
+/* static */
+void HelperThread::ThreadMain(InternalThreadPool* pool, HelperThread* helper) {
+  ThisThread::SetName("JS Helper");
+
+  helper->ensureRegisteredWithProfiler();
+  helper->threadLoop(pool);
+  helper->unregisterWithProfilerIfNeeded();
+}
+
+void HelperThread::ensureRegisteredWithProfiler() {
+  if (profilingStack) {
+    return;
+  }
+
+  // Note: To avoid dead locks, we should not hold on the helper thread lock
+  // while calling this function. This is safe because the registerThread field
+  // is a WriteOnceData<> type stored on the global helper tread state.
+  JS::RegisterThreadCallback callback = HelperThreadState().registerThread;
+  if (callback) {
+    profilingStack =
+        callback("JS Helper", reinterpret_cast<void*>(GetNativeStackBase()));
+  }
+}
+
+void HelperThread::unregisterWithProfilerIfNeeded() {
+  if (!profilingStack) {
+    return;
+  }
+
+  // Note: To avoid dead locks, we should not hold on the helper thread lock
+  // while calling this function. This is safe because the unregisterThread
+  // field is a WriteOnceData<> type stored on the global helper tread state.
+  JS::UnregisterThreadCallback callback = HelperThreadState().unregisterThread;
+  if (callback) {
+    callback();
+    profilingStack = nullptr;
+  }
+}
+
+HelperThread::AutoProfilerLabel::AutoProfilerLabel(
+    HelperThread* helperThread, const char* label,
+    JS::ProfilingCategoryPair categoryPair)
+    : profilingStack(helperThread->profilingStack) {
+  if (profilingStack) {
+    profilingStack->pushLabelFrame(label, nullptr, this, categoryPair);
+  }
+}
+
+HelperThread::AutoProfilerLabel::~AutoProfilerLabel() {
+  if (profilingStack) {
+    profilingStack->pop();
+  }
+}
+
+void HelperThread::threadLoop(InternalThreadPool* pool) {
+  MOZ_ASSERT(CanUseExtraThreads());
+
+  AutoLockHelperThreadState lock;
+
+  while (!pool->terminating) {
+    if (pool->queuedTasks != 0) {
+      pool->queuedTasks--;
+      HelperThreadState().runOneTask(lock);
+      continue;
+    }
+
+    AUTO_PROFILER_LABEL("HelperThread::threadLoop::wait", IDLE);
+    pool->wait(lock);
+  }
+}