The Tor Browser: ipc/chromium/src/base/thread_local_storage

ipc/chromium/src/base/thread_local_storage_win.cc@6474c204b198 (annotated)

ipc/chromium/src/base/thread_local_storage_win.cc

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 #include "base/thread_local_storage.h"
 #include <windows.h>
 #include "base/logging.h"
 // In order to make TLS destructors work, we need to keep function
 // pointers to the destructor for each TLS that we allocate.
 // We make this work by allocating a single OS-level TLS, which
 // contains an array of slots for the application to use.  In
 // parallel, we also allocate an array of destructors, which we
 // keep track of and call when threads terminate.
 // tls_key_ is the one native TLS that we use.  It stores our
 // table.
 long ThreadLocalStorage::tls_key_ = TLS_OUT_OF_INDEXES;
 // tls_max_ is the high-water-mark of allocated thread local storage.
 // We intentionally skip 0 so that it is not confused with an
 // unallocated TLS slot.
 long ThreadLocalStorage::tls_max_ = 1;
 // An array of destructor function pointers for the slots.  If
 // a slot has a destructor, it will be stored in its corresponding
 // entry in this array.
 ThreadLocalStorage::TLSDestructorFunc
   ThreadLocalStorage::tls_destructors_[kThreadLocalStorageSize];
 void** ThreadLocalStorage::Initialize() {
   if (tls_key_ == TLS_OUT_OF_INDEXES) {
     long value = TlsAlloc();
     DCHECK(value != TLS_OUT_OF_INDEXES);
     // Atomically test-and-set the tls_key.  If the key is TLS_OUT_OF_INDEXES,
     // go ahead and set it.  Otherwise, do nothing, as another
     // thread already did our dirty work.
     if (InterlockedCompareExchange(&tls_key_, value, TLS_OUT_OF_INDEXES) !=
             TLS_OUT_OF_INDEXES) {
       // We've been shortcut. Another thread replaced tls_key_ first so we need
       // to destroy our index and use the one the other thread got first.
       TlsFree(value);
     }
   }
   DCHECK(TlsGetValue(tls_key_) == NULL);
   // Create an array to store our data.
   void** tls_data = new void*[kThreadLocalStorageSize];
   memset(tls_data, 0, sizeof(void*[kThreadLocalStorageSize]));
   TlsSetValue(tls_key_, tls_data);
   return tls_data;
 }
 ThreadLocalStorage::Slot::Slot(TLSDestructorFunc destructor)
     : initialized_(false) {
   Initialize(destructor);
 }
 bool ThreadLocalStorage::Slot::Initialize(TLSDestructorFunc destructor) {
   if (tls_key_ == TLS_OUT_OF_INDEXES || !TlsGetValue(tls_key_))
     ThreadLocalStorage::Initialize();
   // Grab a new slot.
   slot_ = InterlockedIncrement(&tls_max_) - 1;
   if (slot_ >= kThreadLocalStorageSize) {
     NOTREACHED();
     return false;
   }
   // Setup our destructor.
   tls_destructors_[slot_] = destructor;
   initialized_ = true;
   return true;
 }
 void ThreadLocalStorage::Slot::Free() {
   // At this time, we don't reclaim old indices for TLS slots.
   // So all we need to do is wipe the destructor.
   tls_destructors_[slot_] = NULL;
   initialized_ = false;
 }
 void* ThreadLocalStorage::Slot::Get() const {
   void** tls_data = static_cast<void**>(TlsGetValue(tls_key_));
   if (!tls_data)
     tls_data = ThreadLocalStorage::Initialize();
   DCHECK(slot_ >= 0 && slot_ < kThreadLocalStorageSize);
   return tls_data[slot_];
 }
 void ThreadLocalStorage::Slot::Set(void* value) {
   void** tls_data = static_cast<void**>(TlsGetValue(tls_key_));
   if (!tls_data)
     tls_data = ThreadLocalStorage::Initialize();
   DCHECK(slot_ >= 0 && slot_ < kThreadLocalStorageSize);
   tls_data[slot_] = value;
 }
 void ThreadLocalStorage::ThreadExit() {
   if (tls_key_ == TLS_OUT_OF_INDEXES)
     return;
   void** tls_data = static_cast<void**>(TlsGetValue(tls_key_));
   // Maybe we have never initialized TLS for this thread.
   if (!tls_data)
     return;
   for (int slot = 0; slot < tls_max_; slot++) {
     if (tls_destructors_[slot] != NULL) {
       void* value = tls_data[slot];
       tls_destructors_[slot](value);
     }
   }
   delete[] tls_data;
   // In case there are other "onexit" handlers...
   TlsSetValue(tls_key_, NULL);
 }
 // 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 http://www.codeproject.com/threads/tls.asp
 // and it works for VC++ 7.0 and later.
 #ifdef _WIN64
 // This makes the linker create the TLS directory if it's not already
 // there.  (e.g. if __declspec(thread) is not used).
 #pragma comment(linker, "/INCLUDE:_tls_used")
 #else  // _WIN64
 // This makes the linker create the TLS directory if it's not already
 // there.  (e.g. if __declspec(thread) is not used).
 #pragma comment(linker, "/INCLUDE:__tls_used")
 #endif  // _WIN64
 // Static callback function to call with each thread termination.
 void NTAPI OnThreadExit(PVOID module, DWORD reason, PVOID reserved)
 {
   // On XP SP0 & SP1, the DLL_PROCESS_ATTACH is never seen. It is sent on SP2+
   // and on W2K and W2K3. So don't assume it is sent.
   if (DLL_THREAD_DETACH == reason || DLL_PROCESS_DETACH == reason)
     ThreadLocalStorage::ThreadExit();
 }
 // .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.
 // By implicitly loaded, I mean that it is directly referenced by the main EXE
 // or by one of its dependent DLLs. Delay-loaded DLL doesn't count as being
 // implicitly loaded.
 //
 // See VC\crt\src\tlssup.c for reference.
 #ifdef _WIN64
 // .CRT section is merged with .rdata on x64 so it must be constant data.
 #pragma const_seg(".CRT$XLB")
 // When defining a const variable, it must have external linkage to be sure the
 // linker doesn't discard it. If this value is discarded, the OnThreadExit
 // function will never be called.
 extern const PIMAGE_TLS_CALLBACK p_thread_callback;
 const PIMAGE_TLS_CALLBACK p_thread_callback = OnThreadExit;
 // Reset the default section.
 #pragma const_seg()
 #else  // _WIN64
 #pragma data_seg(".CRT$XLB")
 PIMAGE_TLS_CALLBACK p_thread_callback = OnThreadExit;
 // Reset the default section.
 #pragma data_seg()
 #endif  // _WIN64

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ipc/chromium/src/base/thread_local_storage_win.cc@6474c204b198 (annotated)

ipc/chromium/src/base/thread_local_storage_win.cc