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//
// Copyright(c) 2014 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// global_state.cpp : Implements functions for querying the thread-local GL and EGL state.
#include "libGLESv2/global_state.h"
#include "common/debug.h"
#include "common/platform.h"
#include "common/tls.h"
namespace gl
{
// In single-threaded cases we can avoid a TLS lookup for the current Context.
//
// Let a global single-threaded context have 3 states: unset, set, and multi-threaded.
// Initially it is unset. Then, on MakeCurrent:
//
// * if the ST context is unset -> set the global context.
// * if the ST context is set and matches the TLS -> set the global context.
// * if the ST context is set and does not match TLS -> set multi-threaded mode.
// * if in multi-threaded mode, unset and subsequently ignore the global context.
//
// Implementation-wise we can use a pointer and a boolean to represent the three modes.
Context *gSingleThreadedContext = nullptr;
bool gIsMultiThreadedContext = false;
} // namespace gl
namespace egl
{
namespace
{
static TLSIndex threadTLS = TLS_INVALID_INDEX;
Debug *g_Debug = nullptr;
std::atomic<std::mutex *> g_Mutex;
Thread *AllocateCurrentThread()
{
ASSERT(threadTLS != TLS_INVALID_INDEX);
if (threadTLS == TLS_INVALID_INDEX)
{
return nullptr;
}
Thread *thread = new Thread();
if (!SetTLSValue(threadTLS, thread))
{
ERR() << "Could not set thread local storage.";
return nullptr;
}
return thread;
}
void AllocateDebug()
{
// All EGL calls use a global lock, this is thread safe
if (g_Debug == nullptr)
{
g_Debug = new Debug();
}
}
void AllocateMutex()
{
if (g_Mutex == nullptr)
{
std::unique_ptr<std::mutex> newMutex(new std::mutex());
std::mutex *expected = nullptr;
if (g_Mutex.compare_exchange_strong(expected, newMutex.get()))
{
newMutex.release();
}
}
}
} // anonymous namespace
std::mutex &GetGlobalMutex()
{
AllocateMutex();
return *g_Mutex;
}
Thread *GetCurrentThread()
{
// Create a TLS index if one has not been created for this DLL
if (threadTLS == TLS_INVALID_INDEX)
{
threadTLS = CreateTLSIndex();
}
Thread *current = static_cast<Thread *>(GetTLSValue(threadTLS));
// ANGLE issue 488: when the dll is loaded after thread initialization,
// thread local storage (current) might not exist yet.
return (current ? current : AllocateCurrentThread());
}
Debug *GetDebug()
{
AllocateDebug();
return g_Debug;
}
void SetContextCurrent(Thread *thread, gl::Context *context)
{
// See above comment on gGlobalContext.
// If the context is in multi-threaded mode, ignore the global context.
if (!gl::gIsMultiThreadedContext)
{
// If the global context is unset or matches the current TLS, set the global context.
if (gl::gSingleThreadedContext == nullptr ||
gl::gSingleThreadedContext == thread->getContext())
{
gl::gSingleThreadedContext = context;
}
else
{
// If the global context is set and does not match TLS, set multi-threaded mode.
gl::gSingleThreadedContext = nullptr;
gl::gIsMultiThreadedContext = true;
}
}
thread->setCurrent(context);
}
} // namespace egl
#ifdef ANGLE_PLATFORM_WINDOWS
namespace egl
{
namespace
{
bool DeallocateCurrentThread()
{
Thread *thread = static_cast<Thread *>(GetTLSValue(threadTLS));
SafeDelete(thread);
return SetTLSValue(threadTLS, nullptr);
}
void DeallocateDebug()
{
SafeDelete(g_Debug);
}
void DeallocateMutex()
{
std::mutex *mutex = g_Mutex.exchange(nullptr);
{
// Wait for the mutex to become released by other threads before deleting.
std::lock_guard<std::mutex> lock(*mutex);
}
SafeDelete(mutex);
}
bool InitializeProcess()
{
ASSERT(g_Debug == nullptr);
AllocateDebug();
AllocateMutex();
threadTLS = CreateTLSIndex();
if (threadTLS == TLS_INVALID_INDEX)
{
return false;
}
return AllocateCurrentThread() != nullptr;
}
bool TerminateProcess()
{
DeallocateDebug();
DeallocateMutex();
if (!DeallocateCurrentThread())
{
return false;
}
if (threadTLS != TLS_INVALID_INDEX)
{
TLSIndex tlsCopy = threadTLS;
threadTLS = TLS_INVALID_INDEX;
if (!DestroyTLSIndex(tlsCopy))
{
return false;
}
}
return true;
}
} // anonymous namespace
} // namespace egl
extern "C" BOOL WINAPI DllMain(HINSTANCE, DWORD reason, LPVOID)
{
switch (reason)
{
case DLL_PROCESS_ATTACH:
return static_cast<BOOL>(egl::InitializeProcess());
case DLL_THREAD_ATTACH:
return static_cast<BOOL>(egl::AllocateCurrentThread() != nullptr);
case DLL_THREAD_DETACH:
return static_cast<BOOL>(egl::DeallocateCurrentThread());
case DLL_PROCESS_DETACH:
return static_cast<BOOL>(egl::TerminateProcess());
}
return TRUE;
}
#endif // ANGLE_PLATFORM_WINDOWS
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