WTF::ThreadSpecific should use base::ThreadLocalStorage.

third_party/WebKit/Source/wtf/ThreadSpecific.h

Index: third_party/WebKit/Source/wtf/ThreadSpecific.h
diff --git a/third_party/WebKit/Source/wtf/ThreadSpecific.h b/third_party/WebKit/Source/wtf/ThreadSpecific.h
index 2e82293b59ea0f9fb2b5c81bc52b279ea5513cb1..36ff6568f2cdce8ceb5d4c748005dc8e2219efd2 100644
--- a/third_party/WebKit/Source/wtf/ThreadSpecific.h
+++ b/third_party/WebKit/Source/wtf/ThreadSpecific.h
@@ -42,244 +42,58 @@
 #ifndef WTF_ThreadSpecific_h
 #define WTF_ThreadSpecific_h
 
+#include "base/threading/thread_local_storage.h"
 #include "wtf/Allocator.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/Partitions.h"
-#include "wtf/StdLibExtras.h"
 #include "wtf/WTF.h"
-#include "wtf/WTFExport.h"
-
-#if OS(POSIX)
-#include <pthread.h>
-#elif OS(WIN)
-#include <windows.h>
-#endif
 
 namespace WTF {
 
-#if OS(WIN)
-// ThreadSpecificThreadExit should be called each time when a thread is detached.
-// This is done automatically for threads created with WTF::createThread.
-WTF_EXPORT void ThreadSpecificThreadExit();
-#endif
-
-template<typename T> class ThreadSpecific {
+template<typename T>
+class ThreadSpecific {
     USING_FAST_MALLOC(ThreadSpecific);
     WTF_MAKE_NONCOPYABLE(ThreadSpecific);
 public:
-    ThreadSpecific();
-    bool isSet(); // Useful as a fast check to see if this thread has set this value.
-    T* operator->();
-    operator T*();
-    T& operator*();
+    ThreadSpecific()
+        : m_slot(&destory)
+    { }
 
-private:
-#if OS(WIN)
-    WTF_EXPORT friend void ThreadSpecificThreadExit();
-#endif
+    operator T*() { return get(); }
+    T* operator->() { return get(); }
+    T& operator*() { return *get(); }
 
+private:
     // Not implemented. It's technically possible to destroy a thread specific key, but one would need
     // to make sure that all values have been destroyed already (usually, that all threads that used it
     // have exited). It's unlikely that any user of this call will be in that situation - and having
     // a destructor defined can be confusing, given that it has such strong pre-requisites to work correctly.
     ~ThreadSpecific();
 
-    T* get();
-    void set(T*);
-    void static destroy(void* ptr);
-
-    struct Data {
-        WTF_MAKE_NONCOPYABLE(Data);
-    public:
-        Data(T* value, ThreadSpecific<T>* owner) : value(value), owner(owner) {}
-
-        T* value;
-        ThreadSpecific<T>* owner;
-#if OS(WIN)
-        void (*destructor)(void*);
-#endif
-    };
-
-#if OS(POSIX)
-    pthread_key_t m_key;
-#elif OS(WIN)
-    int m_index;
-#endif
-};
-
-#if OS(POSIX)
-
-typedef pthread_key_t ThreadSpecificKey;
-
-inline void threadSpecificKeyCreate(ThreadSpecificKey* key, void (*destructor)(void *))
-{
-    int error = pthread_key_create(key, destructor);
-    if (error)
-        CRASH();
-}
-
-inline void threadSpecificKeyDelete(ThreadSpecificKey key)
-{
-    int error = pthread_key_delete(key);
-    if (error)
-        CRASH();
-}
-
-inline void threadSpecificSet(ThreadSpecificKey key, void* value)
-{
-    pthread_setspecific(key, value);
-}
-
-inline void* threadSpecificGet(ThreadSpecificKey key)
-{
-    return pthread_getspecific(key);
-}
-
-template<typename T>
-inline ThreadSpecific<T>::ThreadSpecific()
-{
-    int error = pthread_key_create(&m_key, destroy);
-    if (error)
-        CRASH();
-}
-
-template<typename T>
-inline T* ThreadSpecific<T>::get()
-{
-    Data* data = static_cast<Data*>(pthread_getspecific(m_key));
-    return data ? data->value : 0;
-}
-
-template<typename T>
-inline void ThreadSpecific<T>::set(T* ptr)
-{
-    ASSERT(!get());
-    pthread_setspecific(m_key, new Data(ptr, this));
-}
-
-#elif OS(WIN)
-
-// TLS_OUT_OF_INDEXES is not defined on WinCE.
-#ifndef TLS_OUT_OF_INDEXES
-#define TLS_OUT_OF_INDEXES 0xffffffff
-#endif
-
-// The maximum number of TLS keys that can be created. For simplification, we assume that:
-// 1) Once the instance of ThreadSpecific<> is created, it will not be destructed until the program dies.
-// 2) We do not need to hold many instances of ThreadSpecific<> data. This fixed number should be far enough.
-const int kMaxTlsKeySize = 256;
-
-WTF_EXPORT long& tlsKeyCount();
-WTF_EXPORT DWORD* tlsKeys();
-
-class PlatformThreadSpecificKey;
-typedef PlatformThreadSpecificKey* ThreadSpecificKey;
-
-WTF_EXPORT void threadSpecificKeyCreate(ThreadSpecificKey*, void (*)(void *));
-WTF_EXPORT void threadSpecificKeyDelete(ThreadSpecificKey);
-WTF_EXPORT void threadSpecificSet(ThreadSpecificKey, void*);
-WTF_EXPORT void* threadSpecificGet(ThreadSpecificKey);
-
-template<typename T>
-inline ThreadSpecific<T>::ThreadSpecific()
-    : m_index(-1)
-{
-    DWORD tlsKey = TlsAlloc();
-    if (tlsKey == TLS_OUT_OF_INDEXES)
-        CRASH();
-
-    m_index = InterlockedIncrement(&tlsKeyCount()) - 1;
-    if (m_index >= kMaxTlsKeySize)
-        CRASH();
-    tlsKeys()[m_index] = tlsKey;
-}
-
-template<typename T>
-inline ThreadSpecific<T>::~ThreadSpecific()
-{
-    // Does not invoke destructor functions. They will be called from ThreadSpecificThreadExit when the thread is detached.
-    TlsFree(tlsKeys()[m_index]);
-}
-
-template<typename T>
-inline T* ThreadSpecific<T>::get()
-{
-    Data* data = static_cast<Data*>(TlsGetValue(tlsKeys()[m_index]));
-    return data ? data->value : 0;
-}
-
-template<typename T>
-inline void ThreadSpecific<T>::set(T* ptr)
-{
-    ASSERT(!get());
-    Data* data = new Data(ptr, this);
-    data->destructor = &ThreadSpecific<T>::destroy;
-    TlsSetValue(tlsKeys()[m_index], data);
-}
-
-#else
-#error ThreadSpecific is not implemented for this platform.
-#endif
-
-template<typename T>
-inline void ThreadSpecific<T>::destroy(void* ptr)
-{
-    if (isShutdown())
-        return;
-
-    Data* data = static_cast<Data*>(ptr);
-
-#if OS(POSIX)
-    // We want get() to keep working while data destructor works, because it can be called indirectly by the destructor.
-    // Some pthreads implementations zero out the pointer before calling destroy(), so we temporarily reset it.
-    pthread_setspecific(data->owner->m_key, ptr);
-#endif
-
-    data->value->~T();
-    Partitions::fastFree(data->value);
-
-#if OS(POSIX)
-    pthread_setspecific(data->owner->m_key, 0);
-#elif OS(WIN)
-    TlsSetValue(tlsKeys()[data->owner->m_index], 0);
-#else
-#error ThreadSpecific is not implemented for this platform.
-#endif
-
-    delete data;
-}
-
-template<typename T>
-inline bool ThreadSpecific<T>::isSet()
-{
-    return !!get();
-}
-
-template<typename T>
-inline ThreadSpecific<T>::operator T*()
-{
-    T* ptr = static_cast<T*>(get());
-    if (!ptr) {
-        // Set up thread-specific value's memory pointer before invoking constructor, in case any function it calls
-        // needs to access the value, to avoid recursion.
-        ptr = static_cast<T*>(Partitions::fastZeroedMalloc(sizeof(T), WTF_HEAP_PROFILER_TYPE_NAME(T)));
-        set(ptr);
-        new (NotNull, ptr) T;
+    T* get()
+    {
+        T* ptr = static_cast<T*>(m_slot.Get());
+        if (!ptr) {
+            // Set up thread-specific value's memory pointer before invoking constructor, in case any function it calls
+            // needs to access the value, to avoid recursion.
+            ptr = static_cast<T*>(Partitions::fastZeroedMalloc(sizeof(T), WTF_HEAP_PROFILER_TYPE_NAME(T)));
+            m_slot.Set(ptr);
+            new (NotNull, ptr) T;
+        }
+        return ptr;
     }
-    return ptr;
-}
 
-template<typename T>
-inline T* ThreadSpecific<T>::operator->()
-{
-    return operator T*();
-}
+    static void destory(void* value)
+    {
+        if (isShutdown())

[haraken, 2016/04/01 12:28:35]

I'm not sure if this check is needed though.

+            return;
+        T* ptr = static_cast<T*>(value);
+        ptr->~T();
+        Partitions::fastFree(ptr);
+    }
 
-template<typename T>
-inline T& ThreadSpecific<T>::operator*()
-{
-    return *operator T*();
-}
+    base::ThreadLocalStorage::Slot m_slot;
+};
 
 } // namespace WTF