Reland^3 r22105 "Remove static initializer from isolate"

This time:
When accessing the isolate from the sampler signal handler, don't try
to take the global lock. A sampler should only be active if there is
already an isolate on that thread, so we don't need to check whether
the TLS key is already created.

BUG=none
R=dcarney@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/378513002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22235 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/isolate.cc

@@ -46,6 +46,7 @@ int ThreadId::AllocateThreadId() {
 
 
 int ThreadId::GetCurrentThreadId() {
+  Isolate::EnsureInitialized();
   int thread_id = base::Thread::GetThreadLocalInt(Isolate::thread_id_key_);
   if (thread_id == 0) {
     thread_id = AllocateThreadId();
@@ -104,24 +105,17 @@ base::Thread::LocalStorageKey Isolate::per_isolate_thread_data_key_;
 #ifdef DEBUG
 base::Thread::LocalStorageKey PerThreadAssertScopeBase::thread_local_key;
 #endif  // DEBUG
-base::Mutex Isolate::process_wide_mutex_;
-// TODO(dcarney): Remove with default isolate.
-enum DefaultIsolateStatus {
-  kDefaultIsolateUninitialized,
-  kDefaultIsolateInitialized,
-  kDefaultIsolateCrashIfInitialized
-};
-static DefaultIsolateStatus default_isolate_status_ =
-    kDefaultIsolateUninitialized;
+base::LazyMutex Isolate::process_wide_mutex_ = LAZY_MUTEX_INITIALIZER;
 Isolate::ThreadDataTable* Isolate::thread_data_table_ = NULL;
 base::Atomic32 Isolate::isolate_counter_ = 0;
 
 Isolate::PerIsolateThreadData*
     Isolate::FindOrAllocatePerThreadDataForThisThread() {
+  EnsureInitialized();
   ThreadId thread_id = ThreadId::Current();
   PerIsolateThreadData* per_thread = NULL;
   {
-    base::LockGuard<base::Mutex> lock_guard(&process_wide_mutex_);
+    base::LockGuard<base::Mutex> lock_guard(process_wide_mutex_.Pointer());
     per_thread = thread_data_table_->Lookup(this, thread_id);
     if (per_thread == NULL) {
       per_thread = new PerIsolateThreadData(this, thread_id);
@@ -141,25 +135,18 @@ Isolate::PerIsolateThreadData* Isolate::FindPerThreadDataForThisThread() {
 
 Isolate::PerIsolateThreadData* Isolate::FindPerThreadDataForThread(
     ThreadId thread_id) {
+  EnsureInitialized();
   PerIsolateThreadData* per_thread = NULL;
   {
-    base::LockGuard<base::Mutex> lock_guard(&process_wide_mutex_);
+    base::LockGuard<base::Mutex> lock_guard(process_wide_mutex_.Pointer());
     per_thread = thread_data_table_->Lookup(this, thread_id);
   }
   return per_thread;
 }
 
 
-void Isolate::SetCrashIfDefaultIsolateInitialized() {
-  base::LockGuard<base::Mutex> lock_guard(&process_wide_mutex_);
-  CHECK(default_isolate_status_ != kDefaultIsolateInitialized);
-  default_isolate_status_ = kDefaultIsolateCrashIfInitialized;
-}
-
-
-void Isolate::EnsureDefaultIsolate() {
-  base::LockGuard<base::Mutex> lock_guard(&process_wide_mutex_);
-  CHECK(default_isolate_status_ != kDefaultIsolateCrashIfInitialized);
+void Isolate::EnsureInitialized() {
+  base::LockGuard<base::Mutex> lock_guard(process_wide_mutex_.Pointer());
   if (thread_data_table_ == NULL) {
     isolate_key_ = base::Thread::CreateThreadLocalKey();
     thread_id_key_ = base::Thread::CreateThreadLocalKey();
@@ -172,10 +159,6 @@ void Isolate::EnsureDefaultIsolate() {
   }
 }
 
-struct StaticInitializer {
-  StaticInitializer() { Isolate::EnsureDefaultIsolate(); }
-} static_initializer;
-
 
 Address Isolate::get_address_from_id(Isolate::AddressId id) {
   return isolate_addresses_[id];
@@ -1533,7 +1516,7 @@ void Isolate::TearDown() {
   Deinit();
 
   {
-    base::LockGuard<base::Mutex> lock_guard(&process_wide_mutex_);
+    base::LockGuard<base::Mutex> lock_guard(process_wide_mutex_.Pointer());
     thread_data_table_->RemoveAllThreads(this);
   }
 
@@ -1634,6 +1617,7 @@ void Isolate::PushToPartialSnapshotCache(Object* obj) {
 
 void Isolate::SetIsolateThreadLocals(Isolate* isolate,
                                      PerIsolateThreadData* data) {
+  EnsureInitialized();
   base::Thread::SetThreadLocal(isolate_key_, isolate);
   base::Thread::SetThreadLocal(per_isolate_thread_data_key_, data);
 }

src/isolate.h

@@ -447,12 +447,14 @@ class Isolate {
   // Returns the PerIsolateThreadData for the current thread (or NULL if one is
   // not currently set).
   static PerIsolateThreadData* CurrentPerIsolateThreadData() {
+    EnsureInitialized();
     return reinterpret_cast<PerIsolateThreadData*>(
         base::Thread::GetThreadLocal(per_isolate_thread_data_key_));
   }
 
   // Returns the isolate inside which the current thread is running.
   INLINE(static Isolate* Current()) {
+    EnsureInitialized();
     Isolate* isolate = reinterpret_cast<Isolate*>(
         base::Thread::GetExistingThreadLocal(isolate_key_));
     ASSERT(isolate != NULL);
@@ -460,6 +462,14 @@ class Isolate {
   }
 
   INLINE(static Isolate* UncheckedCurrent()) {
+    EnsureInitialized();
+    return reinterpret_cast<Isolate*>(
+        base::Thread::GetThreadLocal(isolate_key_));
+  }
+
+  // Like UncheckedCurrent, but skips the check that |isolate_key_| was
+  // initialized. Callers have to ensure that themselves.
+  INLINE(static Isolate* UnsafeCurrent()) {
     return reinterpret_cast<Isolate*>(
         base::Thread::GetThreadLocal(isolate_key_));
   }
@@ -485,13 +495,6 @@ class Isolate {
 
   static void GlobalTearDown();
 
-  static void SetCrashIfDefaultIsolateInitialized();
-  // Ensures that process-wide resources and the default isolate have been
-  // allocated. It is only necessary to call this method in rare cases, for
-  // example if you are using V8 from within the body of a static initializer.
-  // Safe to call multiple times.
-  static void EnsureDefaultIsolate();
-
   // Find the PerThread for this particular (isolate, thread) combination
   // If one does not yet exist, return null.
   PerIsolateThreadData* FindPerThreadDataForThisThread();
@@ -504,11 +507,13 @@ class Isolate {
   // Used internally for V8 threads that do not execute JavaScript but still
   // are part of the domain of an isolate (like the context switcher).
   static base::Thread::LocalStorageKey isolate_key() {
+    EnsureInitialized();
     return isolate_key_;
   }
 
   // Returns the key used to store process-wide thread IDs.
   static base::Thread::LocalStorageKey thread_id_key() {
+    EnsureInitialized();
     return thread_id_key_;
   }
 
@@ -1089,6 +1094,8 @@ class Isolate {
   void CountUsage(v8::Isolate::UseCounterFeature feature);
 
  private:
+  static void EnsureInitialized();
+
   Isolate();
 
   friend struct GlobalState;
@@ -1148,7 +1155,7 @@ class Isolate {
   };
 
   // This mutex protects highest_thread_id_ and thread_data_table_.
-  static base::Mutex process_wide_mutex_;
+  static base::LazyMutex process_wide_mutex_;
 
   static base::Thread::LocalStorageKey per_isolate_thread_data_key_;
   static base::Thread::LocalStorageKey isolate_key_;

src/sampler.cc

@@ -331,7 +331,7 @@ void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
 #else
   USE(info);
   if (signal != SIGPROF) return;
-  Isolate* isolate = Isolate::UncheckedCurrent();
+  Isolate* isolate = Isolate::UnsafeCurrent();
   if (isolate == NULL || !isolate->IsInitialized() || !isolate->IsInUse()) {
     // We require a fully initialized and entered isolate.
     return;

tools/check-static-initializers.sh

@@ -32,8 +32,7 @@
 # Allow:
 #  - _GLOBAL__I__ZN2v810LineEditor6first_E
 #  - _GLOBAL__I__ZN2v88internal32AtomicOps_Internalx86CPUFeaturesE
-#  - _GLOBAL__I__ZN2v88internal8ThreadId18highest_thread_id_E
-expected_static_init_count=3
+expected_static_init_count=2
 
 v8_root=$(readlink -f $(dirname $BASH_SOURCE)/../)