1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/ipc/chromium/src/base/thread_local_storage_win.cc Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,186 @@
1.4 +// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
1.5 +// Use of this source code is governed by a BSD-style license that can be
1.6 +// found in the LICENSE file.
1.7 +
1.8 +#include "base/thread_local_storage.h"
1.9 +
1.10 +#include <windows.h>
1.11 +
1.12 +#include "base/logging.h"
1.13 +
1.14 +// In order to make TLS destructors work, we need to keep function
1.15 +// pointers to the destructor for each TLS that we allocate.
1.16 +// We make this work by allocating a single OS-level TLS, which
1.17 +// contains an array of slots for the application to use. In
1.18 +// parallel, we also allocate an array of destructors, which we
1.19 +// keep track of and call when threads terminate.
1.20 +
1.21 +// tls_key_ is the one native TLS that we use. It stores our
1.22 +// table.
1.23 +long ThreadLocalStorage::tls_key_ = TLS_OUT_OF_INDEXES;
1.24 +
1.25 +// tls_max_ is the high-water-mark of allocated thread local storage.
1.26 +// We intentionally skip 0 so that it is not confused with an
1.27 +// unallocated TLS slot.
1.28 +long ThreadLocalStorage::tls_max_ = 1;
1.29 +
1.30 +// An array of destructor function pointers for the slots. If
1.31 +// a slot has a destructor, it will be stored in its corresponding
1.32 +// entry in this array.
1.33 +ThreadLocalStorage::TLSDestructorFunc
1.34 + ThreadLocalStorage::tls_destructors_[kThreadLocalStorageSize];
1.35 +
1.36 +void** ThreadLocalStorage::Initialize() {
1.37 + if (tls_key_ == TLS_OUT_OF_INDEXES) {
1.38 + long value = TlsAlloc();
1.39 + DCHECK(value != TLS_OUT_OF_INDEXES);
1.40 +
1.41 + // Atomically test-and-set the tls_key. If the key is TLS_OUT_OF_INDEXES,
1.42 + // go ahead and set it. Otherwise, do nothing, as another
1.43 + // thread already did our dirty work.
1.44 + if (InterlockedCompareExchange(&tls_key_, value, TLS_OUT_OF_INDEXES) !=
1.45 + TLS_OUT_OF_INDEXES) {
1.46 + // We've been shortcut. Another thread replaced tls_key_ first so we need
1.47 + // to destroy our index and use the one the other thread got first.
1.48 + TlsFree(value);
1.49 + }
1.50 + }
1.51 + DCHECK(TlsGetValue(tls_key_) == NULL);
1.52 +
1.53 + // Create an array to store our data.
1.54 + void** tls_data = new void*[kThreadLocalStorageSize];
1.55 + memset(tls_data, 0, sizeof(void*[kThreadLocalStorageSize]));
1.56 + TlsSetValue(tls_key_, tls_data);
1.57 + return tls_data;
1.58 +}
1.59 +
1.60 +ThreadLocalStorage::Slot::Slot(TLSDestructorFunc destructor)
1.61 + : initialized_(false) {
1.62 + Initialize(destructor);
1.63 +}
1.64 +
1.65 +bool ThreadLocalStorage::Slot::Initialize(TLSDestructorFunc destructor) {
1.66 + if (tls_key_ == TLS_OUT_OF_INDEXES || !TlsGetValue(tls_key_))
1.67 + ThreadLocalStorage::Initialize();
1.68 +
1.69 + // Grab a new slot.
1.70 + slot_ = InterlockedIncrement(&tls_max_) - 1;
1.71 + if (slot_ >= kThreadLocalStorageSize) {
1.72 + NOTREACHED();
1.73 + return false;
1.74 + }
1.75 +
1.76 + // Setup our destructor.
1.77 + tls_destructors_[slot_] = destructor;
1.78 + initialized_ = true;
1.79 + return true;
1.80 +}
1.81 +
1.82 +void ThreadLocalStorage::Slot::Free() {
1.83 + // At this time, we don't reclaim old indices for TLS slots.
1.84 + // So all we need to do is wipe the destructor.
1.85 + tls_destructors_[slot_] = NULL;
1.86 + initialized_ = false;
1.87 +}
1.88 +
1.89 +void* ThreadLocalStorage::Slot::Get() const {
1.90 + void** tls_data = static_cast<void**>(TlsGetValue(tls_key_));
1.91 + if (!tls_data)
1.92 + tls_data = ThreadLocalStorage::Initialize();
1.93 + DCHECK(slot_ >= 0 && slot_ < kThreadLocalStorageSize);
1.94 + return tls_data[slot_];
1.95 +}
1.96 +
1.97 +void ThreadLocalStorage::Slot::Set(void* value) {
1.98 + void** tls_data = static_cast<void**>(TlsGetValue(tls_key_));
1.99 + if (!tls_data)
1.100 + tls_data = ThreadLocalStorage::Initialize();
1.101 + DCHECK(slot_ >= 0 && slot_ < kThreadLocalStorageSize);
1.102 + tls_data[slot_] = value;
1.103 +}
1.104 +
1.105 +void ThreadLocalStorage::ThreadExit() {
1.106 + if (tls_key_ == TLS_OUT_OF_INDEXES)
1.107 + return;
1.108 +
1.109 + void** tls_data = static_cast<void**>(TlsGetValue(tls_key_));
1.110 +
1.111 + // Maybe we have never initialized TLS for this thread.
1.112 + if (!tls_data)
1.113 + return;
1.114 +
1.115 + for (int slot = 0; slot < tls_max_; slot++) {
1.116 + if (tls_destructors_[slot] != NULL) {
1.117 + void* value = tls_data[slot];
1.118 + tls_destructors_[slot](value);
1.119 + }
1.120 + }
1.121 +
1.122 + delete[] tls_data;
1.123 +
1.124 + // In case there are other "onexit" handlers...
1.125 + TlsSetValue(tls_key_, NULL);
1.126 +}
1.127 +
1.128 +// Thread Termination Callbacks.
1.129 +// Windows doesn't support a per-thread destructor with its
1.130 +// TLS primitives. So, we build it manually by inserting a
1.131 +// function to be called on each thread's exit.
1.132 +// This magic is from http://www.codeproject.com/threads/tls.asp
1.133 +// and it works for VC++ 7.0 and later.
1.134 +
1.135 +#ifdef _WIN64
1.136 +
1.137 +// This makes the linker create the TLS directory if it's not already
1.138 +// there. (e.g. if __declspec(thread) is not used).
1.139 +#pragma comment(linker, "/INCLUDE:_tls_used")
1.140 +
1.141 +#else // _WIN64
1.142 +
1.143 +// This makes the linker create the TLS directory if it's not already
1.144 +// there. (e.g. if __declspec(thread) is not used).
1.145 +#pragma comment(linker, "/INCLUDE:__tls_used")
1.146 +
1.147 +#endif // _WIN64
1.148 +
1.149 +// Static callback function to call with each thread termination.
1.150 +void NTAPI OnThreadExit(PVOID module, DWORD reason, PVOID reserved)
1.151 +{
1.152 + // On XP SP0 & SP1, the DLL_PROCESS_ATTACH is never seen. It is sent on SP2+
1.153 + // and on W2K and W2K3. So don't assume it is sent.
1.154 + if (DLL_THREAD_DETACH == reason || DLL_PROCESS_DETACH == reason)
1.155 + ThreadLocalStorage::ThreadExit();
1.156 +}
1.157 +
1.158 +// .CRT$XLA to .CRT$XLZ is an array of PIMAGE_TLS_CALLBACK pointers that are
1.159 +// called automatically by the OS loader code (not the CRT) when the module is
1.160 +// loaded and on thread creation. They are NOT called if the module has been
1.161 +// loaded by a LoadLibrary() call. It must have implicitly been loaded at
1.162 +// process startup.
1.163 +// By implicitly loaded, I mean that it is directly referenced by the main EXE
1.164 +// or by one of its dependent DLLs. Delay-loaded DLL doesn't count as being
1.165 +// implicitly loaded.
1.166 +//
1.167 +// See VC\crt\src\tlssup.c for reference.
1.168 +#ifdef _WIN64
1.169 +
1.170 +// .CRT section is merged with .rdata on x64 so it must be constant data.
1.171 +#pragma const_seg(".CRT$XLB")
1.172 +// When defining a const variable, it must have external linkage to be sure the
1.173 +// linker doesn't discard it. If this value is discarded, the OnThreadExit
1.174 +// function will never be called.
1.175 +extern const PIMAGE_TLS_CALLBACK p_thread_callback;
1.176 +const PIMAGE_TLS_CALLBACK p_thread_callback = OnThreadExit;
1.177 +
1.178 +// Reset the default section.
1.179 +#pragma const_seg()
1.180 +
1.181 +#else // _WIN64
1.182 +
1.183 +#pragma data_seg(".CRT$XLB")
1.184 +PIMAGE_TLS_CALLBACK p_thread_callback = OnThreadExit;
1.185 +
1.186 +// Reset the default section.
1.187 +#pragma data_seg()
1.188 +
1.189 +#endif // _WIN64
