gecko-dev/netwerk/cache2/CacheIOThread.cpp

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C++

/* 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 "CacheIOThread.h"
#include "CacheFileIOManager.h"
#include "nsIRunnable.h"
#include "nsISupportsImpl.h"
#include "nsPrintfCString.h"
#include "nsThreadUtils.h"
#include "mozilla/IOInterposer.h"
#include "GeckoProfiler.h"
#ifdef XP_WIN
#include <windows.h>
#endif
#ifdef MOZ_TASK_TRACER
#include "GeckoTaskTracer.h"
#include "TracedTaskCommon.h"
#endif
namespace mozilla {
namespace net {
namespace { // anon
class CacheIOTelemetry
{
public:
typedef CacheIOThread::EventQueue::size_type size_type;
static size_type mMinLengthToReport[CacheIOThread::LAST_LEVEL];
static void Report(uint32_t aLevel, size_type aLength);
};
static CacheIOTelemetry::size_type const kGranularity = 30;
CacheIOTelemetry::size_type
CacheIOTelemetry::mMinLengthToReport[CacheIOThread::LAST_LEVEL] = {
kGranularity, kGranularity, kGranularity, kGranularity,
kGranularity, kGranularity, kGranularity, kGranularity
};
// static
void CacheIOTelemetry::Report(uint32_t aLevel, CacheIOTelemetry::size_type aLength)
{
if (mMinLengthToReport[aLevel] > aLength) {
return;
}
static Telemetry::HistogramID telemetryID[] = {
Telemetry::HTTP_CACHE_IO_QUEUE_2_OPEN_PRIORITY,
Telemetry::HTTP_CACHE_IO_QUEUE_2_READ_PRIORITY,
Telemetry::HTTP_CACHE_IO_QUEUE_2_MANAGEMENT,
Telemetry::HTTP_CACHE_IO_QUEUE_2_OPEN,
Telemetry::HTTP_CACHE_IO_QUEUE_2_READ,
Telemetry::HTTP_CACHE_IO_QUEUE_2_WRITE_PRIORITY,
Telemetry::HTTP_CACHE_IO_QUEUE_2_WRITE,
Telemetry::HTTP_CACHE_IO_QUEUE_2_INDEX,
Telemetry::HTTP_CACHE_IO_QUEUE_2_EVICT
};
// Each bucket is a multiply of kGranularity (30, 60, 90..., 300+)
aLength = (aLength / kGranularity);
// Next time report only when over the current length + kGranularity
mMinLengthToReport[aLevel] = (aLength + 1) * kGranularity;
// 10 is number of buckets we have in each probe
aLength = std::min<size_type>(aLength, 10);
Telemetry::Accumulate(telemetryID[aLevel], aLength - 1); // counted from 0
}
} // anon
namespace detail {
/**
* Helper class encapsulating platform-specific code to cancel
* any pending IO operation taking too long. Solely used during
* shutdown to prevent any IO shutdown hangs.
* Mainly designed for using Win32 CancelSynchronousIo function.
*/
class BlockingIOWatcher
{
#ifdef XP_WIN
typedef BOOL(WINAPI* TCancelSynchronousIo)(HANDLE hThread);
TCancelSynchronousIo mCancelSynchronousIo;
// The native handle to the thread
HANDLE mThread;
// Event signaling back to the main thread, see NotifyOperationDone.
HANDLE mEvent;
#endif
public:
// Created and destroyed on the main thread only
BlockingIOWatcher();
~BlockingIOWatcher();
// Called on the IO thread to grab the platform specific
// reference to it.
void InitThread();
// If there is a blocking operation being handled on the IO
// thread, this is called on the main thread during shutdown.
// Waits for notification from the IO thread for up to two seconds.
// If that times out, it attempts to cancel the IO operation.
void WatchAndCancel(Monitor& aMonitor);
// Called by the IO thread after each operation has been
// finished (after each Run() call). This wakes the main
// thread up and makes WatchAndCancel() early exit and become
// a no-op.
void NotifyOperationDone();
};
#ifdef XP_WIN
BlockingIOWatcher::BlockingIOWatcher()
: mCancelSynchronousIo(NULL)
, mThread(NULL)
, mEvent(NULL)
{
HMODULE kernel32_dll = GetModuleHandle("kernel32.dll");
if (!kernel32_dll) {
return;
}
FARPROC ptr = GetProcAddress(kernel32_dll, "CancelSynchronousIo");
if (!ptr) {
return;
}
mCancelSynchronousIo = reinterpret_cast<TCancelSynchronousIo>(ptr);
mEvent = ::CreateEvent(NULL, TRUE, FALSE, NULL);
}
BlockingIOWatcher::~BlockingIOWatcher()
{
if (mEvent) {
CloseHandle(mEvent);
}
if (mThread) {
CloseHandle(mThread);
}
}
void BlockingIOWatcher::InitThread()
{
// GetCurrentThread() only returns a pseudo handle, hence DuplicateHandle
BOOL result = ::DuplicateHandle(
GetCurrentProcess(),
GetCurrentThread(),
GetCurrentProcess(),
&mThread,
0,
FALSE,
DUPLICATE_SAME_ACCESS);
}
void BlockingIOWatcher::WatchAndCancel(Monitor& aMonitor)
{
if (!mEvent) {
return;
}
// Reset before we enter the monitor to raise the chance we catch
// the currently pending IO op completion.
::ResetEvent(mEvent);
HANDLE thread;
{
MonitorAutoLock lock(aMonitor);
thread = mThread;
if (!thread) {
return;
}
}
LOG(("Blocking IO operation pending on IO thread, waiting..."));
// It seems wise to use the I/O lag time as a maximum time to wait
// for an operation to finish. When that times out and cancelation
// succeeds, there will be no other IO operation permitted. By default
// this is two seconds.
uint32_t maxLag = std::min<uint32_t>(5, CacheObserver::MaxShutdownIOLag()) * 1000;
DWORD result = ::WaitForSingleObject(mEvent, maxLag);
if (result == WAIT_TIMEOUT) {
LOG(("CacheIOThread: Attempting to cancel a long blocking IO operation"));
BOOL result = mCancelSynchronousIo(thread);
if (result) {
LOG((" cancelation signal succeeded"));
} else {
DWORD error = GetLastError();
LOG((" cancelation signal failed with GetLastError=%u", error));
}
}
}
void BlockingIOWatcher::NotifyOperationDone()
{
if (mEvent) {
::SetEvent(mEvent);
}
}
#else // WIN
// Stub code only (we don't implement IO cancelation for this platform)
BlockingIOWatcher::BlockingIOWatcher() { }
BlockingIOWatcher::~BlockingIOWatcher() { }
void BlockingIOWatcher::InitThread() { }
void BlockingIOWatcher::WatchAndCancel(Monitor&) { }
void BlockingIOWatcher::NotifyOperationDone() { }
#endif
} // detail
CacheIOThread* CacheIOThread::sSelf = nullptr;
NS_IMPL_ISUPPORTS(CacheIOThread, nsIThreadObserver)
CacheIOThread::CacheIOThread()
: mMonitor("CacheIOThread")
, mThread(nullptr)
, mXPCOMThread(nullptr)
, mLowestLevelWaiting(LAST_LEVEL)
, mCurrentlyExecutingLevel(0)
, mHasXPCOMEvents(false)
, mRerunCurrentEvent(false)
, mShutdown(false)
, mIOCancelableEvents(0)
#ifdef DEBUG
, mInsideLoop(true)
#endif
{
for (uint32_t i = 0; i < LAST_LEVEL; ++i) {
mQueueLength[i] = 0;
}
sSelf = this;
}
CacheIOThread::~CacheIOThread()
{
if (mXPCOMThread) {
nsIThread *thread = mXPCOMThread;
thread->Release();
}
sSelf = nullptr;
#ifdef DEBUG
for (uint32_t level = 0; level < LAST_LEVEL; ++level) {
MOZ_ASSERT(!mEventQueue[level].Length());
}
#endif
}
nsresult CacheIOThread::Init()
{
{
MonitorAutoLock lock(mMonitor);
// Yeah, there is not a thread yet, but we want to make sure
// the sequencing is correct.
mBlockingIOWatcher = MakeUnique<detail::BlockingIOWatcher>();
}
mThread = PR_CreateThread(PR_USER_THREAD, ThreadFunc, this,
PR_PRIORITY_NORMAL, PR_GLOBAL_THREAD,
PR_JOINABLE_THREAD, 128 * 1024);
if (!mThread) {
return NS_ERROR_FAILURE;
}
return NS_OK;
}
nsresult CacheIOThread::Dispatch(nsIRunnable* aRunnable, uint32_t aLevel)
{
return Dispatch(do_AddRef(aRunnable), aLevel);
}
nsresult CacheIOThread::Dispatch(already_AddRefed<nsIRunnable> aRunnable,
uint32_t aLevel)
{
NS_ENSURE_ARG(aLevel < LAST_LEVEL);
nsCOMPtr<nsIRunnable> runnable(aRunnable);
// Runnable is always expected to be non-null, hard null-check bellow.
MOZ_ASSERT(runnable);
MonitorAutoLock lock(mMonitor);
if (mShutdown && (PR_GetCurrentThread() != mThread))
return NS_ERROR_UNEXPECTED;
return DispatchInternal(runnable.forget(), aLevel);
}
nsresult CacheIOThread::DispatchAfterPendingOpens(nsIRunnable* aRunnable)
{
// Runnable is always expected to be non-null, hard null-check bellow.
MOZ_ASSERT(aRunnable);
MonitorAutoLock lock(mMonitor);
if (mShutdown && (PR_GetCurrentThread() != mThread))
return NS_ERROR_UNEXPECTED;
// Move everything from later executed OPEN level to the OPEN_PRIORITY level
// where we post the (eviction) runnable.
mQueueLength[OPEN_PRIORITY] += mEventQueue[OPEN].Length();
mQueueLength[OPEN] -= mEventQueue[OPEN].Length();
mEventQueue[OPEN_PRIORITY].AppendElements(mEventQueue[OPEN]);
mEventQueue[OPEN].Clear();
return DispatchInternal(do_AddRef(aRunnable), OPEN_PRIORITY);
}
nsresult CacheIOThread::DispatchInternal(already_AddRefed<nsIRunnable> aRunnable,
uint32_t aLevel)
{
nsCOMPtr<nsIRunnable> runnable(aRunnable);
#ifdef MOZ_TASK_TRACER
if (tasktracer::IsStartLogging()) {
runnable = tasktracer::CreateTracedRunnable(runnable.forget());
(static_cast<tasktracer::TracedRunnable*>(runnable.get()))->DispatchTask();
}
#endif
if (NS_WARN_IF(!runnable))
return NS_ERROR_NULL_POINTER;
mMonitor.AssertCurrentThreadOwns();
++mQueueLength[aLevel];
mEventQueue[aLevel].AppendElement(runnable.forget());
if (mLowestLevelWaiting > aLevel)
mLowestLevelWaiting = aLevel;
mMonitor.NotifyAll();
return NS_OK;
}
bool CacheIOThread::IsCurrentThread()
{
return mThread == PR_GetCurrentThread();
}
uint32_t CacheIOThread::QueueSize(bool highPriority)
{
MonitorAutoLock lock(mMonitor);
if (highPriority) {
return mQueueLength[OPEN_PRIORITY] + mQueueLength[READ_PRIORITY];
}
return mQueueLength[OPEN_PRIORITY] + mQueueLength[READ_PRIORITY] +
mQueueLength[MANAGEMENT] + mQueueLength[OPEN] + mQueueLength[READ];
}
bool CacheIOThread::YieldInternal()
{
if (!IsCurrentThread()) {
NS_WARNING("Trying to yield to priority events on non-cache2 I/O thread? "
"You probably do something wrong.");
return false;
}
if (mCurrentlyExecutingLevel == XPCOM_LEVEL) {
// Doesn't make any sense, since this handler is the one
// that would be executed as the next one.
return false;
}
if (!EventsPending(mCurrentlyExecutingLevel))
return false;
mRerunCurrentEvent = true;
return true;
}
void CacheIOThread::Shutdown()
{
if (!mThread) {
return;
}
{
MonitorAutoLock lock(mMonitor);
mShutdown = true;
mMonitor.NotifyAll();
}
PR_JoinThread(mThread);
mThread = nullptr;
}
void CacheIOThread::CancelBlockingIO()
{
// This is an attempt to cancel any blocking I/O operation taking
// too long time.
if (!mBlockingIOWatcher) {
return;
}
if (!mIOCancelableEvents) {
LOG(("CacheIOThread::CancelBlockingIO, no blocking operation to cancel"));
return;
}
// OK, when we are here, we are processing an IO on the thread that
// can be cancelled.
mBlockingIOWatcher->WatchAndCancel(mMonitor);
}
already_AddRefed<nsIEventTarget> CacheIOThread::Target()
{
nsCOMPtr<nsIEventTarget> target;
target = mXPCOMThread;
if (!target && mThread)
{
MonitorAutoLock lock(mMonitor);
while (!mXPCOMThread) {
lock.Wait();
}
target = mXPCOMThread;
}
return target.forget();
}
// static
void CacheIOThread::ThreadFunc(void* aClosure)
{
// XXXmstange We'd like to register this thread with the profiler, but doing
// so causes leaks, see bug 1323100.
PR_SetCurrentThreadName("Cache2 I/O");
mozilla::IOInterposer::RegisterCurrentThread();
CacheIOThread* thread = static_cast<CacheIOThread*>(aClosure);
thread->ThreadFunc();
mozilla::IOInterposer::UnregisterCurrentThread();
}
void CacheIOThread::ThreadFunc()
{
nsCOMPtr<nsIThreadInternal> threadInternal;
{
MonitorAutoLock lock(mMonitor);
MOZ_ASSERT(mBlockingIOWatcher);
mBlockingIOWatcher->InitThread();
// This creates nsThread for this PRThread
nsCOMPtr<nsIThread> xpcomThread = NS_GetCurrentThread();
threadInternal = do_QueryInterface(xpcomThread);
if (threadInternal)
threadInternal->SetObserver(this);
mXPCOMThread = xpcomThread.forget().take();
lock.NotifyAll();
do {
loopStart:
// Reset the lowest level now, so that we can detect a new event on
// a lower level (i.e. higher priority) has been scheduled while
// executing any previously scheduled event.
mLowestLevelWaiting = LAST_LEVEL;
// Process xpcom events first
while (mHasXPCOMEvents) {
mHasXPCOMEvents = false;
mCurrentlyExecutingLevel = XPCOM_LEVEL;
MonitorAutoUnlock unlock(mMonitor);
bool processedEvent;
nsresult rv;
do {
nsIThread *thread = mXPCOMThread;
rv = thread->ProcessNextEvent(false, &processedEvent);
MOZ_ASSERT(mBlockingIOWatcher);
mBlockingIOWatcher->NotifyOperationDone();
} while (NS_SUCCEEDED(rv) && processedEvent);
}
uint32_t level;
for (level = 0; level < LAST_LEVEL; ++level) {
if (!mEventQueue[level].Length()) {
// no events on this level, go to the next level
continue;
}
LoopOneLevel(level);
// Go to the first (lowest) level again
goto loopStart;
}
if (EventsPending()) {
continue;
}
if (mShutdown) {
break;
}
lock.Wait(PR_INTERVAL_NO_TIMEOUT);
} while (true);
MOZ_ASSERT(!EventsPending());
#ifdef DEBUG
// This is for correct assertion on XPCOM events dispatch.
mInsideLoop = false;
#endif
} // lock
if (threadInternal)
threadInternal->SetObserver(nullptr);
}
void CacheIOThread::LoopOneLevel(uint32_t aLevel)
{
EventQueue events;
events.SwapElements(mEventQueue[aLevel]);
EventQueue::size_type length = events.Length();
mCurrentlyExecutingLevel = aLevel;
bool returnEvents = false;
bool reportTelementry = true;
EventQueue::size_type index;
{
MonitorAutoUnlock unlock(mMonitor);
for (index = 0; index < length; ++index) {
if (EventsPending(aLevel)) {
// Somebody scheduled a new event on a lower level, break and harry
// to execute it! Don't forget to return what we haven't exec.
returnEvents = true;
break;
}
if (reportTelementry) {
reportTelementry = false;
CacheIOTelemetry::Report(aLevel, length);
}
// Drop any previous flagging, only an event on the current level may set
// this flag.
mRerunCurrentEvent = false;
events[index]->Run();
MOZ_ASSERT(mBlockingIOWatcher);
mBlockingIOWatcher->NotifyOperationDone();
if (mRerunCurrentEvent) {
// The event handler yields to higher priority events and wants to rerun.
returnEvents = true;
break;
}
--mQueueLength[aLevel];
// Release outside the lock.
events[index] = nullptr;
}
}
if (returnEvents)
mEventQueue[aLevel].InsertElementsAt(0, events.Elements() + index, length - index);
}
bool CacheIOThread::EventsPending(uint32_t aLastLevel)
{
return mLowestLevelWaiting < aLastLevel || mHasXPCOMEvents;
}
NS_IMETHODIMP CacheIOThread::OnDispatchedEvent(nsIThreadInternal *thread)
{
MonitorAutoLock lock(mMonitor);
mHasXPCOMEvents = true;
MOZ_ASSERT(mInsideLoop);
lock.Notify();
return NS_OK;
}
NS_IMETHODIMP CacheIOThread::OnProcessNextEvent(nsIThreadInternal *thread, bool mayWait)
{
return NS_OK;
}
NS_IMETHODIMP CacheIOThread::AfterProcessNextEvent(nsIThreadInternal *thread,
bool eventWasProcessed)
{
return NS_OK;
}
// Memory reporting
size_t CacheIOThread::SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const
{
MonitorAutoLock lock(const_cast<CacheIOThread*>(this)->mMonitor);
size_t n = 0;
n += mallocSizeOf(mThread);
for (uint32_t level = 0; level < LAST_LEVEL; ++level) {
n += mEventQueue[level].ShallowSizeOfExcludingThis(mallocSizeOf);
// Events referenced by the queues are arbitrary objects we cannot be sure
// are reported elsewhere as well as probably not implementing nsISizeOf
// interface. Deliberatly omitting them from reporting here.
}
return n;
}
size_t CacheIOThread::SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const
{
return mallocSizeOf(this) + SizeOfExcludingThis(mallocSizeOf);
}
CacheIOThread::Cancelable::Cancelable(bool aCancelable)
: mCancelable(aCancelable)
{
// This will only ever be used on the I/O thread,
// which is expected to be alive longer than this class.
MOZ_ASSERT(CacheIOThread::sSelf);
MOZ_ASSERT(CacheIOThread::sSelf->IsCurrentThread());
if (mCancelable) {
++CacheIOThread::sSelf->mIOCancelableEvents;
}
}
CacheIOThread::Cancelable::~Cancelable()
{
MOZ_ASSERT(CacheIOThread::sSelf);
if (mCancelable) {
--CacheIOThread::sSelf->mIOCancelableEvents;
}
}
} // namespace net
} // namespace mozilla