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/*
* Copyright (C) 2007-2018 Apple Inc. All rights reserved.
* Copyright (C) 2007 Justin Haygood <jhaygood@reaktix.com>
* Copyright (C) 2017 Yusuke Suzuki <utatane.tea@gmail.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <mutex>
#include <stdint.h>
#include <wtf/Atomics.h>
#include <wtf/Expected.h>
#include <wtf/FastTLS.h>
#include <wtf/Function.h>
#include <wtf/HashSet.h>
#include <wtf/PlatformRegisters.h>
#include <wtf/Ref.h>
#include <wtf/RefPtr.h>
#include <wtf/StackBounds.h>
#include <wtf/StackStats.h>
#include <wtf/ThreadSafeRefCounted.h>
#include <wtf/Vector.h>
#include <wtf/WordLock.h>
#include <wtf/text/AtomicStringTable.h>
#if USE(PTHREADS) && !OS(DARWIN)
#include <signal.h>
#endif
namespace WTF {
class AbstractLocker;
class ThreadMessageData;
enum class ThreadGroupAddResult;
class ThreadGroup;
class PrintStream;
// This function can be called from any threads.
WTF_EXPORT_PRIVATE void initializeThreading();
#if USE(PTHREADS)
// We use SIGUSR1 to suspend and resume machine threads in JavaScriptCore.
constexpr const int SigThreadSuspendResume = SIGUSR1;
#endif
enum class GCThreadType : uint8_t {
None = 0,
Main,
Helper,
};
class Thread : public ThreadSafeRefCounted<Thread> {
public:
friend class ThreadGroup;
friend WTF_EXPORT_PRIVATE void initializeThreading();
WTF_EXPORT_PRIVATE ~Thread();
// Returns nullptr if thread creation failed.
// The thread name must be a literal since on some platforms it's passed in to the thread.
WTF_EXPORT_PRIVATE static Ref<Thread> create(const char* threadName, Function<void()>&&);
// Returns Thread object.
static Thread& current();
// Set of all WTF::Thread created threads.
WTF_EXPORT_PRIVATE static HashSet<Thread*>& allThreads(const LockHolder&);
WTF_EXPORT_PRIVATE static Lock& allThreadsMutex();
#if OS(WINDOWS)
// Returns ThreadIdentifier directly. It is useful if the user only cares about identity
// of threads. At that time, users should know that holding this ThreadIdentifier does not ensure
// that the thread information is alive. While Thread::current() is not safe if it is called
// from the destructor of the other TLS data, currentID() always returns meaningful thread ID.
WTF_EXPORT_PRIVATE static ThreadIdentifier currentID();
ThreadIdentifier id() const { return m_id; }
#endif
WTF_EXPORT_PRIVATE void changePriority(int);
WTF_EXPORT_PRIVATE int waitForCompletion();
WTF_EXPORT_PRIVATE void detach();
#if OS(DARWIN)
using PlatformSuspendError = kern_return_t;
#elif USE(PTHREADS)
using PlatformSuspendError = int;
#elif OS(WINDOWS)
using PlatformSuspendError = DWORD;
#endif
WTF_EXPORT_PRIVATE Expected<void, PlatformSuspendError> suspend();
WTF_EXPORT_PRIVATE void resume();
WTF_EXPORT_PRIVATE size_t getRegisters(PlatformRegisters&);
#if USE(PTHREADS)
WTF_EXPORT_PRIVATE bool signal(int signalNumber);
#endif
// Mark the current thread as requiring UI responsiveness.
// relativePriority is a value in the range [-15, 0] where a lower value indicates a lower priority.
WTF_EXPORT_PRIVATE static void setCurrentThreadIsUserInteractive(int relativePriority = 0);
WTF_EXPORT_PRIVATE static void setCurrentThreadIsUserInitiated(int relativePriority = 0);
#if HAVE(QOS_CLASSES)
WTF_EXPORT_PRIVATE static void setGlobalMaxQOSClass(qos_class_t);
WTF_EXPORT_PRIVATE static qos_class_t adjustedQOSClass(qos_class_t);
#endif
// Called in the thread during initialization.
// Helpful for platforms where the thread name must be set from within the thread.
static void initializeCurrentThreadInternal(const char* threadName);
static void initializeCurrentThreadEvenIfNonWTFCreated();
WTF_EXPORT_PRIVATE static const unsigned lockSpinLimit;
WTF_EXPORT_PRIVATE static void yield();
WTF_EXPORT_PRIVATE static bool exchangeIsCompilationThread(bool newValue);
WTF_EXPORT_PRIVATE static void registerGCThread(GCThreadType);
WTF_EXPORT_PRIVATE static bool mayBeGCThread();
WTF_EXPORT_PRIVATE void dump(PrintStream& out) const;
static void initializePlatformThreading();
const StackBounds& stack() const
{
return m_stack;
}
AtomicStringTable* atomicStringTable()
{
return m_currentAtomicStringTable;
}
AtomicStringTable* setCurrentAtomicStringTable(AtomicStringTable* atomicStringTable)
{
AtomicStringTable* oldAtomicStringTable = m_currentAtomicStringTable;
m_currentAtomicStringTable = atomicStringTable;
return oldAtomicStringTable;
}
#if ENABLE(STACK_STATS)
StackStats::PerThreadStats& stackStats()
{
return m_stackStats;
}
#endif
void* savedStackPointerAtVMEntry()
{
return m_savedStackPointerAtVMEntry;
}
void setSavedStackPointerAtVMEntry(void* stackPointerAtVMEntry)
{
m_savedStackPointerAtVMEntry = stackPointerAtVMEntry;
}
void* savedLastStackTop()
{
return m_savedLastStackTop;
}
void setSavedLastStackTop(void* lastStackTop)
{
m_savedLastStackTop = lastStackTop;
}
#if OS(DARWIN)
mach_port_t machThread() { return m_platformThread; }
#endif
bool isCompilationThread() const { return m_isCompilationThread; }
GCThreadType gcThreadType() const { return static_cast<GCThreadType>(m_gcThreadType); }
struct NewThreadContext;
static void entryPoint(NewThreadContext*);
protected:
Thread();
void initializeInThread();
// Internal platform-specific Thread establishment implementation.
bool establishHandle(NewThreadContext*);
#if USE(PTHREADS)
void establishPlatformSpecificHandle(PlatformThreadHandle);
#else
void establishPlatformSpecificHandle(PlatformThreadHandle, ThreadIdentifier);
#endif
#if USE(PTHREADS) && !OS(DARWIN)
static void signalHandlerSuspendResume(int, siginfo_t*, void* ucontext);
#endif
static const char* normalizeThreadName(const char* threadName);
enum JoinableState : uint8_t {
// The default thread state. The thread can be joined on.
Joinable,
// Somebody waited on this thread to exit and this thread finally exited. This state is here because there can be a
// period of time between when the thread exits (which causes pthread_join to return and the remainder of waitOnThreadCompletion to run)
// and when threadDidExit is called. We need threadDidExit to take charge and delete the thread data since there's
// nobody else to pick up the slack in this case (since waitOnThreadCompletion has already returned).
Joined,
// The thread has been detached and can no longer be joined on. At this point, the thread must take care of cleaning up after itself.
Detached,
};
JoinableState joinableState() const { return m_joinableState; }
void didBecomeDetached() { m_joinableState = Detached; }
void didExit();
void didJoin() { m_joinableState = Joined; }
bool hasExited() const { return m_didExit; }
// These functions are only called from ThreadGroup.
ThreadGroupAddResult addToThreadGroup(const AbstractLocker& threadGroupLocker, ThreadGroup&);
void removeFromThreadGroup(const AbstractLocker& threadGroupLocker, ThreadGroup&);
// The Thread instance is ref'ed and held in thread-specific storage. It will be deref'ed by destructTLS at thread destruction time.
// For pthread, it employs pthreads-specific 2-pass destruction to reliably remove Thread.
// For Windows, we use thread_local to defer thread TLS destruction. It assumes regular ThreadSpecific
// types don't use multiple-pass destruction.
#if !HAVE(FAST_TLS)
static WTF_EXPORT_PRIVATE ThreadSpecificKey s_key;
// One time initialization for this class as a whole.
// This method must be called before initializeTLS() and it is not thread-safe.
static void initializeTLSKey();
#endif
// Creates and puts an instance of Thread into thread-specific storage.
static Thread& initializeTLS(Ref<Thread>&&);
WTF_EXPORT_PRIVATE static Thread& initializeCurrentTLS();
// Returns nullptr if thread-specific storage was not initialized.
static Thread* currentMayBeNull();
#if OS(WINDOWS)
WTF_EXPORT_PRIVATE static Thread* currentDying();
static RefPtr<Thread> get(ThreadIdentifier);
#endif
// This thread-specific destructor is called 2 times when thread terminates:
// - first, when all the other thread-specific destructors are called, it simply remembers it was 'destroyed once'
// and (1) re-sets itself into the thread-specific slot or (2) constructs thread local value to call it again later.
// - second, after all thread-specific destructors were invoked, it gets called again - this time, we remove the
// Thread from the threadMap, completing the cleanup.
static void THREAD_SPECIFIC_CALL destructTLS(void* data);
JoinableState m_joinableState { Joinable };
bool m_isShuttingDown : 1;
bool m_didExit : 1;
bool m_isDestroyedOnce : 1;
bool m_isCompilationThread: 1;
unsigned m_gcThreadType : 2;
// Lock & ParkingLot rely on ThreadSpecific. But Thread object can be destroyed even after ThreadSpecific things are destroyed.
// Use WordLock since WordLock does not depend on ThreadSpecific and this "Thread".
WordLock m_mutex;
StackBounds m_stack { StackBounds::emptyBounds() };
Vector<std::weak_ptr<ThreadGroup>> m_threadGroups;
PlatformThreadHandle m_handle;
#if OS(WINDOWS)
ThreadIdentifier m_id { 0 };
#elif OS(DARWIN)
mach_port_t m_platformThread { MACH_PORT_NULL };
#elif USE(PTHREADS)
PlatformRegisters* m_platformRegisters { nullptr };
unsigned m_suspendCount { 0 };
#endif
AtomicStringTable* m_currentAtomicStringTable { nullptr };
AtomicStringTable m_defaultAtomicStringTable;
#if ENABLE(STACK_STATS)
StackStats::PerThreadStats m_stackStats;
#endif
void* m_savedStackPointerAtVMEntry { nullptr };
void* m_savedLastStackTop;
public:
void* m_apiData { nullptr };
};
inline Thread::Thread()
: m_isShuttingDown(false)
, m_didExit(false)
, m_isDestroyedOnce(false)
, m_isCompilationThread(false)
, m_gcThreadType(static_cast<unsigned>(GCThreadType::None))
{
}
inline Thread* Thread::currentMayBeNull()
{
#if !HAVE(FAST_TLS)
ASSERT(s_key != InvalidThreadSpecificKey);
return static_cast<Thread*>(threadSpecificGet(s_key));
#else
return static_cast<Thread*>(_pthread_getspecific_direct(WTF_THREAD_DATA_KEY));
#endif
}
inline Thread& Thread::current()
{
// WRT WebCore:
// Thread::current() is used on main thread before it could possibly be used
// on secondary ones, so there is no need for synchronization here.
// WRT JavaScriptCore:
// Thread::initializeTLSKey() is initially called from initializeThreading(), ensuring
// this is initially called in a std::call_once locked context.
#if !HAVE(FAST_TLS)
if (UNLIKELY(Thread::s_key == InvalidThreadSpecificKey))
WTF::initializeThreading();
#endif
if (auto* thread = currentMayBeNull())
return *thread;
#if OS(WINDOWS)
if (auto* thread = currentDying())
return *thread;
#endif
return initializeCurrentTLS();
}
} // namespace WTF
using WTF::Thread;
using WTF::GCThreadType;