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/*
* Copyright (C) 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "perfetto/base/build_config.h"
#if PERFETTO_BUILDFLAG(PERFETTO_OS_WIN)
#include <Windows.h>
#include "perfetto/ext/base/thread_task_runner.h"
#include "perfetto/tracing/internal/tracing_tls.h"
#include "perfetto/tracing/platform.h"
// Thread Termination Callbacks.
// Windows doesn't support a per-thread destructor with its
// TLS primitives. So, we build it manually by inserting a
// function to be called on each thread's exit.
// This magic is from chromium's base/threading/thread_local_storage_win.cc
// which in turn is from http://www.codeproject.com/threads/tls.asp.
#ifdef _WIN64
#pragma comment(linker, "/INCLUDE:_tls_used")
#pragma comment(linker, "/INCLUDE:perfetto_thread_callback_base")
#else
#pragma comment(linker, "/INCLUDE:__tls_used")
#pragma comment(linker, "/INCLUDE:_perfetto_thread_callback_base")
#endif
namespace perfetto {
namespace {
class PlatformWindows : public Platform {
public:
static PlatformWindows* instance;
PlatformWindows();
~PlatformWindows() override;
ThreadLocalObject* GetOrCreateThreadLocalObject() override;
std::unique_ptr<base::TaskRunner> CreateTaskRunner(
const CreateTaskRunnerArgs&) override;
std::string GetCurrentProcessName() override;
void OnThreadExit();
private:
DWORD tls_key_{};
};
using ThreadLocalObject = Platform::ThreadLocalObject;
// static
PlatformWindows* PlatformWindows::instance = nullptr;
PlatformWindows::PlatformWindows() {
instance = this;
tls_key_ = ::TlsAlloc();
PERFETTO_CHECK(tls_key_ != TLS_OUT_OF_INDEXES);
}
PlatformWindows::~PlatformWindows() {
::TlsFree(tls_key_);
instance = nullptr;
}
void PlatformWindows::OnThreadExit() {
auto tls = static_cast<ThreadLocalObject*>(::TlsGetValue(tls_key_));
if (tls) {
// At this point we rely on the TLS object to be still set to the TracingTLS
// we are deleting. See comments in TracingTLS::~TracingTLS().
delete tls;
}
}
ThreadLocalObject* PlatformWindows::GetOrCreateThreadLocalObject() {
void* tls_ptr = ::TlsGetValue(tls_key_);
auto* tls = static_cast<ThreadLocalObject*>(tls_ptr);
if (!tls) {
tls = ThreadLocalObject::CreateInstance().release();
::TlsSetValue(tls_key_, tls);
}
return tls;
}
std::unique_ptr<base::TaskRunner> PlatformWindows::CreateTaskRunner(
const CreateTaskRunnerArgs& args) {
return std::unique_ptr<base::TaskRunner>(new base::ThreadTaskRunner(
base::ThreadTaskRunner::CreateAndStart(args.name_for_debugging)));
}
std::string PlatformWindows::GetCurrentProcessName() {
char buf[MAX_PATH];
auto len = ::GetModuleFileNameA(nullptr /*current*/, buf, sizeof(buf));
std::string name(buf, static_cast<size_t>(len));
size_t sep = name.find_last_of('\\');
if (sep != std::string::npos)
name = name.substr(sep + 1);
return name;
}
} // namespace
// static
Platform* Platform::GetDefaultPlatform() {
static PlatformWindows* thread_safe_init_instance = new PlatformWindows();
return thread_safe_init_instance;
}
} // namespace perfetto
// -----------------------
// Thread-local destructor
// -----------------------
// .CRT$XLA to .CRT$XLZ is an array of PIMAGE_TLS_CALLBACK pointers that are
// called automatically by the OS loader code (not the CRT) when the module is
// loaded and on thread creation. They are NOT called if the module has been
// loaded by a LoadLibrary() call. It must have implicitly been loaded at
// process startup.
// See VC\crt\src\tlssup.c for reference.
// extern "C" suppresses C++ name mangling so we know the symbol name for the
// linker /INCLUDE:symbol pragma above.
extern "C" {
// The linker must not discard perfetto_thread_callback_base. (We force a
// reference to this variable with a linker /INCLUDE:symbol pragma to ensure
// that.) If this variable is discarded, the OnThreadExit function will never be
// called.
void NTAPI PerfettoOnThreadExit(PVOID, DWORD, PVOID);
void NTAPI PerfettoOnThreadExit(PVOID module, DWORD reason, PVOID reserved) {
if (reason == DLL_THREAD_DETACH || reason == DLL_PROCESS_DETACH) {
if (perfetto::PlatformWindows::instance)
perfetto::PlatformWindows::instance->OnThreadExit();
}
}
#ifdef _WIN64
// .CRT section is merged with .rdata on x64 so it must be constant data.
#pragma const_seg(".CRT$XLP")
// When defining a const variable, it must have external linkage to be sure the
// linker doesn't discard it.
extern const PIMAGE_TLS_CALLBACK perfetto_thread_callback_base;
const PIMAGE_TLS_CALLBACK perfetto_thread_callback_base = PerfettoOnThreadExit;
// Reset the default section.
#pragma const_seg()
#else // _WIN64
#pragma data_seg(".CRT$XLP")
PIMAGE_TLS_CALLBACK perfetto_thread_callback_base = PerfettoOnThreadExit;
// Reset the default section.
#pragma data_seg()
#endif // _WIN64
} // extern "C"
#endif // OS_WIN
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