Index: base/threading/thread_local_storage.cc |
diff --git a/base/threading/thread_local_storage_win.cc b/base/threading/thread_local_storage.cc |
similarity index 59% |
copy from base/threading/thread_local_storage_win.cc |
copy to base/threading/thread_local_storage.cc |
index 0ae3cb4c8cd39471b9b532a5dc87e2b5d61647a8..523a0d0ded5d480b6180877fb035c4761f9cb0e3 100644 |
--- a/base/threading/thread_local_storage_win.cc |
+++ b/base/threading/thread_local_storage.cc |
@@ -4,21 +4,22 @@ |
#include "base/threading/thread_local_storage.h" |
-#include <windows.h> |
- |
+#include "base/atomicops.h" |
#include "base/logging.h" |
+using base::internal::PlatformThreadLocalStorage; |
namespace { |
-// 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. |
+// In order to make TLS destructors work, we need to keep around a function |
+// pointer to the destructor for each slot. We keep this array of pointers in a |
+// global (static) array. |
+// We use the single OS-level TLS slot (giving us one pointer per thread) to |
+// hold a pointer to a per-thread array (table) of slots that we allocate to |
+// Chromium consumers. |
// g_native_tls_key is the one native TLS that we use. It stores our table. |
-long g_native_tls_key = TLS_OUT_OF_INDEXES; |
+base::subtle::AtomicWord g_native_tls_key = |
+ PlatformThreadLocalStorage::TLS_KEY_OUT_OF_INDEXES; |
// g_last_used_tls_key is the high-water-mark of allocated thread local storage. |
// Each allocation is an index into our g_tls_destructors[]. Each such index is |
@@ -27,7 +28,7 @@ long g_native_tls_key = TLS_OUT_OF_INDEXES; |
// instance of ThreadLocalStorage::Slot has been freed (i.e., destructor called, |
// etc.). This reserved use of 0 is then stated as the initial value of |
// g_last_used_tls_key, so that the first issued index will be 1. |
-long g_last_used_tls_key = 0; |
+base::subtle::Atomic32 g_last_used_tls_key = 0; |
// The maximum number of 'slots' in our thread local storage stack. |
const int kThreadLocalStorageSize = 64; |
@@ -48,23 +49,43 @@ const int kMaxDestructorIterations = kThreadLocalStorageSize; |
volatile base::ThreadLocalStorage::TLSDestructorFunc |
g_tls_destructors[kThreadLocalStorageSize]; |
+// This function is called to initialize our entire Chromium TLS system. |
+// It may be called very early, and we need to complete most all of the setup |
+// (initialization) before calling *any* memory allocator functions, which may |
+// recursively depend on this initialization. |
+// As a result, we use Atomics, and avoid anything (like a singleton) that might |
+// require memory allocations. |
void** ConstructTlsVector() { |
- if (g_native_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 (TLS_OUT_OF_INDEXES != InterlockedCompareExchange( |
- &g_native_tls_key, value, TLS_OUT_OF_INDEXES)) { |
+ PlatformThreadLocalStorage::TLSKey key = |
+ base::subtle::NoBarrier_Load(&g_native_tls_key); |
+ if (key == PlatformThreadLocalStorage::TLS_KEY_OUT_OF_INDEXES) { |
+ CHECK(PlatformThreadLocalStorage::AllocTLS(&key)); |
+ |
+ // The TLS_KEY_OUT_OF_INDEXES is used to find out whether the key is set or |
+ // not in NoBarrier_CompareAndSwap, but Posix doesn't have invalid key, we |
+ // define an almost impossible value be it. |
+ // If we really get TLS_KEY_OUT_OF_INDEXES as value of key, just alloc |
+ // another TLS slot. |
+ if (key == PlatformThreadLocalStorage::TLS_KEY_OUT_OF_INDEXES) { |
+ PlatformThreadLocalStorage::TLSKey tmp = key; |
+ CHECK(PlatformThreadLocalStorage::AllocTLS(&key) && |
+ key != PlatformThreadLocalStorage::TLS_KEY_OUT_OF_INDEXES); |
+ PlatformThreadLocalStorage::FreeTLS(tmp); |
+ } |
+ // Atomically test-and-set the tls_key. If the key is |
+ // TLS_KEY_OUT_OF_INDEXES, go ahead and set it. Otherwise, do nothing, as |
+ // another thread already did our dirty work. |
+ if (PlatformThreadLocalStorage::TLS_KEY_OUT_OF_INDEXES != |
+ base::subtle::NoBarrier_CompareAndSwap(&g_native_tls_key, |
+ PlatformThreadLocalStorage::TLS_KEY_OUT_OF_INDEXES, key)) { |
// We've been shortcut. Another thread replaced g_native_tls_key first so |
// we need to destroy our index and use the one the other thread got |
// first. |
- TlsFree(value); |
+ PlatformThreadLocalStorage::FreeTLS(key); |
+ key = base::subtle::NoBarrier_Load(&g_native_tls_key); |
} |
} |
- DCHECK(!TlsGetValue(g_native_tls_key)); |
+ CHECK(!PlatformThreadLocalStorage::GetTLSValue(key)); |
// Some allocators, such as TCMalloc, make use of thread local storage. |
// As a result, any attempt to call new (or malloc) will lazily cause such a |
@@ -77,26 +98,18 @@ void** ConstructTlsVector() { |
void* stack_allocated_tls_data[kThreadLocalStorageSize]; |
memset(stack_allocated_tls_data, 0, sizeof(stack_allocated_tls_data)); |
// Ensure that any rentrant calls change the temp version. |
- TlsSetValue(g_native_tls_key, stack_allocated_tls_data); |
+ PlatformThreadLocalStorage::SetTLSValue(key, stack_allocated_tls_data); |
// Allocate an array to store our data. |
void** tls_data = new void*[kThreadLocalStorageSize]; |
memcpy(tls_data, stack_allocated_tls_data, sizeof(stack_allocated_tls_data)); |
- TlsSetValue(g_native_tls_key, tls_data); |
+ PlatformThreadLocalStorage::SetTLSValue(key, tls_data); |
return tls_data; |
} |
-// Called when we terminate a thread, this function calls any TLS destructors |
-// that are pending for this thread. |
-void WinThreadExit() { |
- if (g_native_tls_key == TLS_OUT_OF_INDEXES) |
- return; |
- |
- void** tls_data = static_cast<void**>(TlsGetValue(g_native_tls_key)); |
- // Maybe we have never initialized TLS for this thread. |
- if (!tls_data) |
- return; |
- |
+void OnThreadExitInternal(void* value) { |
+ DCHECK(value); |
+ void** tls_data = static_cast<void**>(value); |
// Some allocators, such as TCMalloc, use TLS. As a result, when a thread |
// terminates, one of the destructor calls we make may be to shut down an |
// allocator. We have to be careful that after we've shutdown all of the |
@@ -109,7 +122,9 @@ void WinThreadExit() { |
void* stack_allocated_tls_data[kThreadLocalStorageSize]; |
memcpy(stack_allocated_tls_data, tls_data, sizeof(stack_allocated_tls_data)); |
// Ensure that any re-entrant calls change the temp version. |
- TlsSetValue(g_native_tls_key, stack_allocated_tls_data); |
+ PlatformThreadLocalStorage::TLSKey key = |
+ base::subtle::NoBarrier_Load(&g_native_tls_key); |
+ PlatformThreadLocalStorage::SetTLSValue(key, stack_allocated_tls_data); |
delete[] tls_data; // Our last dependence on an allocator. |
int remaining_attempts = kMaxDestructorIterations; |
@@ -122,10 +137,13 @@ void WinThreadExit() { |
// allocator) and should also be destroyed last. If we get the order wrong, |
// then we'll itterate several more times, so it is really not that |
// critical (but it might help). |
- for (int slot = g_last_used_tls_key; slot > 0; --slot) { |
+ base::subtle::Atomic32 last_used_tls_key = |
+ base::subtle::NoBarrier_Load(&g_last_used_tls_key); |
+ for (int slot = last_used_tls_key; slot > 0; --slot) { |
void* value = stack_allocated_tls_data[slot]; |
if (value == NULL) |
continue; |
+ |
base::ThreadLocalStorage::TLSDestructorFunc destructor = |
g_tls_destructors[slot]; |
if (destructor == NULL) |
@@ -144,13 +162,35 @@ void WinThreadExit() { |
} |
// Remove our stack allocated vector. |
- TlsSetValue(g_native_tls_key, NULL); |
+ PlatformThreadLocalStorage::SetTLSValue(key, NULL); |
} |
} // namespace |
namespace base { |
+namespace internal { |
+ |
+#if defined(OS_WIN) |
+void PlatformThreadLocalStorage::OnThreadExit() { |
+ PlatformThreadLocalStorage::TLSKey key = |
+ base::subtle::NoBarrier_Load(&g_native_tls_key); |
+ if (key == PlatformThreadLocalStorage::TLS_KEY_OUT_OF_INDEXES) |
+ return; |
+ void *tls_data = GetTLSValue(key); |
+ // Maybe we have never initialized TLS for this thread. |
+ if (!tls_data) |
+ return; |
+ OnThreadExitInternal(tls_data); |
+} |
+#elif defined(OS_POSIX) |
+void PlatformThreadLocalStorage::OnThreadExit(void* value) { |
+ OnThreadExitInternal(value); |
+} |
+#endif // defined(OS_WIN) |
+ |
+} // namespace internal |
+ |
ThreadLocalStorage::Slot::Slot(TLSDestructorFunc destructor) { |
initialized_ = false; |
slot_ = 0; |
@@ -158,16 +198,16 @@ ThreadLocalStorage::Slot::Slot(TLSDestructorFunc destructor) { |
} |
bool ThreadLocalStorage::StaticSlot::Initialize(TLSDestructorFunc destructor) { |
- if (g_native_tls_key == TLS_OUT_OF_INDEXES || !TlsGetValue(g_native_tls_key)) |
+ PlatformThreadLocalStorage::TLSKey key = |
+ base::subtle::NoBarrier_Load(&g_native_tls_key); |
+ if (key == PlatformThreadLocalStorage::TLS_KEY_OUT_OF_INDEXES || |
+ !PlatformThreadLocalStorage::GetTLSValue(key)) |
ConstructTlsVector(); |
// Grab a new slot. |
- slot_ = InterlockedIncrement(&g_last_used_tls_key); |
+ slot_ = base::subtle::NoBarrier_AtomicIncrement(&g_last_used_tls_key, 1); |
DCHECK_GT(slot_, 0); |
- if (slot_ >= kThreadLocalStorageSize) { |
- NOTREACHED(); |
- return false; |
- } |
+ CHECK_LT(slot_, kThreadLocalStorageSize); |
// Setup our destructor. |
g_tls_destructors[slot_] = destructor; |
@@ -186,7 +226,9 @@ void ThreadLocalStorage::StaticSlot::Free() { |
} |
void* ThreadLocalStorage::StaticSlot::Get() const { |
- void** tls_data = static_cast<void**>(TlsGetValue(g_native_tls_key)); |
+ void** tls_data = static_cast<void**>( |
+ PlatformThreadLocalStorage::GetTLSValue( |
+ base::subtle::NoBarrier_Load(&g_native_tls_key))); |
if (!tls_data) |
tls_data = ConstructTlsVector(); |
DCHECK_GT(slot_, 0); |
@@ -195,7 +237,9 @@ void* ThreadLocalStorage::StaticSlot::Get() const { |
} |
void ThreadLocalStorage::StaticSlot::Set(void* value) { |
- void** tls_data = static_cast<void**>(TlsGetValue(g_native_tls_key)); |
+ void** tls_data = static_cast<void**>( |
+ PlatformThreadLocalStorage::GetTLSValue( |
+ base::subtle::NoBarrier_Load(&g_native_tls_key))); |
if (!tls_data) |
tls_data = ConstructTlsVector(); |
DCHECK_GT(slot_, 0); |
@@ -204,74 +248,3 @@ void ThreadLocalStorage::StaticSlot::Set(void* value) { |
} |
} // namespace base |
- |
-// 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. |
- |
-// Force a reference to _tls_used to make the linker create the TLS directory |
-// if it's not already there. (e.g. if __declspec(thread) is not used). |
-// Force a reference to p_thread_callback_base to prevent whole program |
-// optimization from discarding the variable. |
-#ifdef _WIN64 |
- |
-#pragma comment(linker, "/INCLUDE:_tls_used") |
-#pragma comment(linker, "/INCLUDE:p_thread_callback_base") |
- |
-#else // _WIN64 |
- |
-#pragma comment(linker, "/INCLUDE:__tls_used") |
-#pragma comment(linker, "/INCLUDE:_p_thread_callback_base") |
- |
-#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) |
- WinThreadExit(); |
-} |
- |
-// .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. |
- |
-// 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 p_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. |
-#ifdef _WIN64 |
- |
-// .CRT section is merged with .rdata on x64 so it must be constant data. |
-#pragma const_seg(".CRT$XLB") |
-// When defining a const variable, it must have external linkage to be sure the |
-// linker doesn't discard it. |
-extern const PIMAGE_TLS_CALLBACK p_thread_callback_base; |
-const PIMAGE_TLS_CALLBACK p_thread_callback_base = OnThreadExit; |
- |
-// Reset the default section. |
-#pragma const_seg() |
- |
-#else // _WIN64 |
- |
-#pragma data_seg(".CRT$XLB") |
-PIMAGE_TLS_CALLBACK p_thread_callback_base = OnThreadExit; |
- |
-// Reset the default section. |
-#pragma data_seg() |
- |
-#endif // _WIN64 |
-} // extern "C" |