tls.h

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Author : Jamie Madill
Date : 2020-09-20 21:59:24
Hash : cb286073
Message : Use c++ thread_local for current thread. This solves a race condition using the global context. Sadly we can't use an unprotected variable safely because it can be written/read from multiple threads doing MakeCurrent. Has about a 2 ns regression when tested in Linux/Release per call. "null" benchmark test went from 27 -> 29 ns/iteration. Fixes a TSAN warning that popped up in angle_end2end_tests. Test: DrawCallPerfBenchmark.Run/vulkan_null Test: EGLContextASANTest.DestroyContextInUse/ES3_Vulkan Bug: b/168744561 Change-Id: Ic56f3faae81c1087b942a3cfc0e011b9ab439e0f Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2419641 Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>

src/common/tls.h

//
// Copyright 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.
//

// tls.h: Simple cross-platform interface for thread local storage.

#ifndef COMMON_TLS_H_
#define COMMON_TLS_H_

#include "common/angleutils.h"
#include "common/platform.h"

namespace gl
{
class Context;
}

#ifdef ANGLE_PLATFORM_WINDOWS

// TLS does not exist for Windows Store and needs to be emulated
#    ifdef ANGLE_ENABLE_WINDOWS_UWP
#        ifndef TLS_OUT_OF_INDEXES
#            define TLS_OUT_OF_INDEXES static_cast<DWORD>(0xFFFFFFFF)
#        endif
#        ifndef CREATE_SUSPENDED
#            define CREATE_SUSPENDED 0x00000004
#        endif
#    endif
typedef DWORD TLSIndex;
#    define TLS_INVALID_INDEX (TLS_OUT_OF_INDEXES)
#elif defined(ANGLE_PLATFORM_POSIX)
#    include <errno.h>
#    include <pthread.h>
#    include <semaphore.h>
typedef pthread_key_t TLSIndex;
#    define TLS_INVALID_INDEX (static_cast<TLSIndex>(-1))
#else
#    error Unsupported platform.
#endif

// TODO(kbr): for POSIX platforms this will have to be changed to take
// in a destructor function pointer, to allow the thread-local storage
// to be properly deallocated upon thread exit.
TLSIndex CreateTLSIndex();
bool DestroyTLSIndex(TLSIndex index);

bool SetTLSValue(TLSIndex index, void *value);
void *GetTLSValue(TLSIndex index);

#endif  // COMMON_TLS_H_

kc3-lang/angle/src/common/tls.h

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kc3-lang/angle /src/common/tls.h