1 files changed, 342 insertions, 0 deletions
diff --git a/xpcom/threads/nsThreadManager.cpp b/xpcom/threads/nsThreadManager.cpp
new file mode 100644
index 000000000..d1eb84b8f
--- /dev/null
+++ b/xpcom/threads/nsThreadManager.cpp
@@ -0,0 +1,342 @@
+/* -*- 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 "nsThreadManager.h"
+#include "nsThread.h"
+#include "nsThreadUtils.h"
+#include "nsIClassInfoImpl.h"
+#include "nsTArray.h"
+#include "nsAutoPtr.h"
+#include "mozilla/ThreadLocal.h"
+#ifdef MOZ_CANARY
+#include <fcntl.h>
+#include <unistd.h>
+#endif
+
+#include "MainThreadIdlePeriod.h"
+
+using namespace mozilla;
+
+static MOZ_THREAD_LOCAL(bool) sTLSIsMainThread;
+
+bool
+NS_IsMainThread()
+{
+  return sTLSIsMainThread.get();
+}
+
+void
+NS_SetMainThread()
+{
+  if (!sTLSIsMainThread.init()) {
+    MOZ_CRASH();
+  }
+  sTLSIsMainThread.set(true);
+  MOZ_ASSERT(NS_IsMainThread());
+}
+
+typedef nsTArray<NotNull<RefPtr<nsThread>>> nsThreadArray;
+
+//-----------------------------------------------------------------------------
+
+static void
+ReleaseObject(void* aData)
+{
+  static_cast<nsISupports*>(aData)->Release();
+}
+
+// statically allocated instance
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsThreadManager::AddRef()
+{
+  return 2;
+}
+NS_IMETHODIMP_(MozExternalRefCountType)
+nsThreadManager::Release()
+{
+  return 1;
+}
+NS_IMPL_CLASSINFO(nsThreadManager, nullptr,
+                  nsIClassInfo::THREADSAFE | nsIClassInfo::SINGLETON,
+                  NS_THREADMANAGER_CID)
+NS_IMPL_QUERY_INTERFACE_CI(nsThreadManager, nsIThreadManager)
+NS_IMPL_CI_INTERFACE_GETTER(nsThreadManager, nsIThreadManager)
+
+//-----------------------------------------------------------------------------
+
+nsresult
+nsThreadManager::Init()
+{
+  // Child processes need to initialize the thread manager before they
+  // initialize XPCOM in order to set up the crash reporter. This leads to
+  // situations where we get initialized twice.
+  if (mInitialized) {
+    return NS_OK;
+  }
+
+  if (PR_NewThreadPrivateIndex(&mCurThreadIndex, ReleaseObject) == PR_FAILURE) {
+    return NS_ERROR_FAILURE;
+  }
+
+
+#ifdef MOZ_CANARY
+  const int flags = O_WRONLY | O_APPEND | O_CREAT | O_NONBLOCK;
+  const mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
+  char* env_var_flag = getenv("MOZ_KILL_CANARIES");
+  sCanaryOutputFD =
+    env_var_flag ? (env_var_flag[0] ? open(env_var_flag, flags, mode) :
+                                      STDERR_FILENO) :
+                   0;
+#endif
+
+  // Setup "main" thread
+  mMainThread = new nsThread(nsThread::MAIN_THREAD, 0);
+
+  nsresult rv = mMainThread->InitCurrentThread();
+  if (NS_FAILED(rv)) {
+    mMainThread = nullptr;
+    return rv;
+  }
+
+  {
+    nsCOMPtr<nsIIdlePeriod> idlePeriod = new MainThreadIdlePeriod();
+    mMainThread->RegisterIdlePeriod(idlePeriod.forget());
+  }
+
+  // We need to keep a pointer to the current thread, so we can satisfy
+  // GetIsMainThread calls that occur post-Shutdown.
+  mMainThread->GetPRThread(&mMainPRThread);
+
+  mInitialized = true;
+  return NS_OK;
+}
+
+void
+nsThreadManager::Shutdown()
+{
+  MOZ_ASSERT(NS_IsMainThread(), "shutdown not called from main thread");
+
+  // Prevent further access to the thread manager (no more new threads!)
+  //
+  // What happens if shutdown happens before NewThread completes?
+  // We Shutdown() the new thread, and return error if we've started Shutdown
+  // between when NewThread started, and when the thread finished initializing
+  // and registering with ThreadManager.
+  //
+  mInitialized = false;
+
+  // Empty the main thread event queue before we begin shutting down threads.
+  NS_ProcessPendingEvents(mMainThread);
+
+  // We gather the threads from the hashtable into a list, so that we avoid
+  // holding the hashtable lock while calling nsIThread::Shutdown.
+  nsThreadArray threads;
+  {
+    OffTheBooksMutexAutoLock lock(mLock);
+    for (auto iter = mThreadsByPRThread.Iter(); !iter.Done(); iter.Next()) {
+      RefPtr<nsThread>& thread = iter.Data();
+      threads.AppendElement(WrapNotNull(thread));
+      iter.Remove();
+    }
+  }
+
+  // It's tempting to walk the list of threads here and tell them each to stop
+  // accepting new events, but that could lead to badness if one of those
+  // threads is stuck waiting for a response from another thread.  To do it
+  // right, we'd need some way to interrupt the threads.
+  //
+  // Instead, we process events on the current thread while waiting for threads
+  // to shutdown.  This means that we have to preserve a mostly functioning
+  // world until such time as the threads exit.
+
+  // Shutdown all threads that require it (join with threads that we created).
+  for (uint32_t i = 0; i < threads.Length(); ++i) {
+    NotNull<nsThread*> thread = threads[i];
+    if (thread->ShutdownRequired()) {
+      thread->Shutdown();
+    }
+  }
+
+  // NB: It's possible that there are events in the queue that want to *start*
+  // an asynchronous shutdown. But we have already shutdown the threads above,
+  // so there's no need to worry about them. We only have to wait for all
+  // in-flight asynchronous thread shutdowns to complete.
+  mMainThread->WaitForAllAsynchronousShutdowns();
+
+  // In case there are any more events somehow...
+  NS_ProcessPendingEvents(mMainThread);
+
+  // There are no more background threads at this point.
+
+  // Clear the table of threads.
+  {
+    OffTheBooksMutexAutoLock lock(mLock);
+    mThreadsByPRThread.Clear();
+  }
+
+  // Normally thread shutdown clears the observer for the thread, but since the
+  // main thread is special we do it manually here after we're sure all events
+  // have been processed.
+  mMainThread->SetObserver(nullptr);
+  mMainThread->ClearObservers();
+
+  // Release main thread object.
+  mMainThread = nullptr;
+
+  // Remove the TLS entry for the main thread.
+  PR_SetThreadPrivate(mCurThreadIndex, nullptr);
+}
+
+void
+nsThreadManager::RegisterCurrentThread(nsThread& aThread)
+{
+  MOZ_ASSERT(aThread.GetPRThread() == PR_GetCurrentThread(), "bad aThread");
+
+  OffTheBooksMutexAutoLock lock(mLock);
+
+  ++mCurrentNumberOfThreads;
+  if (mCurrentNumberOfThreads > mHighestNumberOfThreads) {
+    mHighestNumberOfThreads = mCurrentNumberOfThreads;
+  }
+
+  mThreadsByPRThread.Put(aThread.GetPRThread(), &aThread);  // XXX check OOM?
+
+  aThread.AddRef();  // for TLS entry
+  PR_SetThreadPrivate(mCurThreadIndex, &aThread);
+}
+
+void
+nsThreadManager::UnregisterCurrentThread(nsThread& aThread)
+{
+  MOZ_ASSERT(aThread.GetPRThread() == PR_GetCurrentThread(), "bad aThread");
+
+  OffTheBooksMutexAutoLock lock(mLock);
+
+  --mCurrentNumberOfThreads;
+  mThreadsByPRThread.Remove(aThread.GetPRThread());
+
+  PR_SetThreadPrivate(mCurThreadIndex, nullptr);
+  // Ref-count balanced via ReleaseObject
+}
+
+nsThread*
+nsThreadManager::GetCurrentThread()
+{
+  // read thread local storage
+  void* data = PR_GetThreadPrivate(mCurThreadIndex);
+  if (data) {
+    return static_cast<nsThread*>(data);
+  }
+
+  if (!mInitialized) {
+    return nullptr;
+  }
+
+  // OK, that's fine.  We'll dynamically create one :-)
+  RefPtr<nsThread> thread = new nsThread(nsThread::NOT_MAIN_THREAD, 0);
+  if (!thread || NS_FAILED(thread->InitCurrentThread())) {
+    return nullptr;
+  }
+
+  return thread.get();  // reference held in TLS
+}
+
+NS_IMETHODIMP
+nsThreadManager::NewThread(uint32_t aCreationFlags,
+                           uint32_t aStackSize,
+                           nsIThread** aResult)
+{
+  // Note: can be called from arbitrary threads
+  
+  // No new threads during Shutdown
+  if (NS_WARN_IF(!mInitialized)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  RefPtr<nsThread> thr = new nsThread(nsThread::NOT_MAIN_THREAD, aStackSize);
+  nsresult rv = thr->Init();  // Note: blocks until the new thread has been set up
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // At this point, we expect that the thread has been registered in mThreadByPRThread;
+  // however, it is possible that it could have also been replaced by now, so
+  // we cannot really assert that it was added.  Instead, kill it if we entered
+  // Shutdown() during/before Init()
+
+  if (NS_WARN_IF(!mInitialized)) {
+    if (thr->ShutdownRequired()) {
+      thr->Shutdown(); // ok if it happens multiple times
+    }
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  thr.forget(aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadManager::GetThreadFromPRThread(PRThread* aThread, nsIThread** aResult)
+{
+  // Keep this functioning during Shutdown
+  if (NS_WARN_IF(!mMainThread)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  if (NS_WARN_IF(!aThread)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  RefPtr<nsThread> temp;
+  {
+    OffTheBooksMutexAutoLock lock(mLock);
+    mThreadsByPRThread.Get(aThread, getter_AddRefs(temp));
+  }
+
+  NS_IF_ADDREF(*aResult = temp);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadManager::GetMainThread(nsIThread** aResult)
+{
+  // Keep this functioning during Shutdown
+  if (NS_WARN_IF(!mMainThread)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  NS_ADDREF(*aResult = mMainThread);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadManager::GetCurrentThread(nsIThread** aResult)
+{
+  // Keep this functioning during Shutdown
+  if (NS_WARN_IF(!mMainThread)) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  *aResult = GetCurrentThread();
+  if (!*aResult) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsThreadManager::GetIsMainThread(bool* aResult)
+{
+  // This method may be called post-Shutdown
+
+  *aResult = (PR_GetCurrentThread() == mMainPRThread);
+  return NS_OK;
+}
+
+uint32_t
+nsThreadManager::GetHighestNumberOfThreads()
+{
+  OffTheBooksMutexAutoLock lock(mLock);
+  return mHighestNumberOfThreads;
+}