Removed MallocHookScope and replaced it with MallocLocker, which behaves like MutexLocker but also …

runtime/vm/malloc_hooks.cc

Index: runtime/vm/malloc_hooks.cc
diff --git a/runtime/vm/malloc_hooks.cc b/runtime/vm/malloc_hooks.cc
index 4f7de9e20d70b8b4c0326e5d47d996f0496ea5dc..a85d22e85f306300ee3b7f499290bd4a7f3f7846 100644
--- a/runtime/vm/malloc_hooks.cc
+++ b/runtime/vm/malloc_hooks.cc
@@ -13,60 +13,33 @@
 #include "platform/assert.h"
 #include "vm/hash_map.h"
 #include "vm/json_stream.h"
-#include "vm/lockers.h"
+#include "vm/os_thread.h"
 
 namespace dart {
 
-// A locker-type class to automatically grab and release the
-// in_malloc_hook_flag_.
-class MallocHookScope {
+// A locker-type class similar to MutexLocker which tracks which thread
+// currently holds the lock. We use this instead of MutexLocker and
+// mutex->IsOwnedByCurrentThread() since IsOwnedByCurrentThread() is only
+// enabled for debug mode.
+class MallocLocker : public ValueObject {
  public:
-  static void InitMallocHookFlag() {
-    MutexLocker ml(malloc_hook_scope_mutex_);
-    ASSERT(in_malloc_hook_flag_ == kUnsetThreadLocalKey);
-    in_malloc_hook_flag_ = OSThread::CreateThreadLocal();
-    OSThread::SetThreadLocal(in_malloc_hook_flag_, 0);
+  explicit MallocLocker(Mutex* mutex, ThreadId* owner)
+      : mutex_(mutex), owner_(owner) {
+    ASSERT(owner != NULL);
+    mutex_->Lock();
+    ASSERT(*owner_ == OSThread::kInvalidThreadId);
+    *owner_ = OSThread::GetCurrentThreadId();
   }
 
-  static void DestroyMallocHookFlag() {
-    MutexLocker ml(malloc_hook_scope_mutex_);
-    ASSERT(in_malloc_hook_flag_ != kUnsetThreadLocalKey);
-    OSThread::DeleteThreadLocal(in_malloc_hook_flag_);
-    in_malloc_hook_flag_ = kUnsetThreadLocalKey;
-  }
-
-  MallocHookScope() {
-    MutexLocker ml(malloc_hook_scope_mutex_);
-    ASSERT(in_malloc_hook_flag_ != kUnsetThreadLocalKey);
-    OSThread::SetThreadLocal(in_malloc_hook_flag_, 1);
-  }
-
-  ~MallocHookScope() {
-    MutexLocker ml(malloc_hook_scope_mutex_);
-    ASSERT(in_malloc_hook_flag_ != kUnsetThreadLocalKey);
-    OSThread::SetThreadLocal(in_malloc_hook_flag_, 0);
-  }
-
-  static bool IsInHook() {
-    MutexLocker ml(malloc_hook_scope_mutex_);
-    if (in_malloc_hook_flag_ == kUnsetThreadLocalKey) {
-      // Bail out if the malloc hook flag is invalid. This means that
-      // MallocHookState::TearDown() has been called and MallocHookScope is no
-      // longer intitialized. Don't worry if MallocHookState::TearDown() is
-      // called before the hooks grab the mutex, since
-      // MallocHooksState::Active() is checked after the lock is taken before
-      // proceeding to act on the allocation/free.
-      return false;
-    }
-    return OSThread::GetThreadLocal(in_malloc_hook_flag_);
+  virtual ~MallocLocker() {
+    ASSERT(*owner_ == OSThread::GetCurrentThreadId());
+    *owner_ = OSThread::kInvalidThreadId;
+    mutex_->Unlock();
   }
 
  private:
-  static Mutex* malloc_hook_scope_mutex_;
-  static ThreadLocalKey in_malloc_hook_flag_;
-
-  DISALLOW_ALLOCATION();
-  DISALLOW_COPY_AND_ASSIGN(MallocHookScope);
+  Mutex* mutex_;
+  ThreadId* owner_;
 };
 
 
@@ -135,6 +108,12 @@ class MallocHooksState : public AllStatic {
   }
 
   static Mutex* malloc_hook_mutex() { return malloc_hook_mutex_; }
+  static ThreadId* malloc_hook_mutex_owner() {
+    return &malloc_hook_mutex_owner_;
+  }
+  static bool IsLockHeldByCurrentThread() {
+    return (malloc_hook_mutex_owner_ == OSThread::GetCurrentThreadId());
+  }
 
   static intptr_t allocation_count() { return allocation_count_; }
 
@@ -179,6 +158,7 @@ class MallocHooksState : public AllStatic {
   static bool active_;
   static intptr_t original_pid_;
   static Mutex* malloc_hook_mutex_;
+  static ThreadId malloc_hook_mutex_owner_;
   static intptr_t allocation_count_;
   static intptr_t heap_allocated_memory_in_bytes_;
   static AddressMap* address_map_;
@@ -187,14 +167,12 @@ class MallocHooksState : public AllStatic {
 };
 
 
-// MallocHookScope state.
-Mutex* MallocHookScope::malloc_hook_scope_mutex_ = new Mutex();
-ThreadLocalKey MallocHookScope::in_malloc_hook_flag_ = kUnsetThreadLocalKey;
-
 // MallocHooks state / locks.
 bool MallocHooksState::active_ = false;
 intptr_t MallocHooksState::original_pid_ = MallocHooksState::kInvalidPid;
 Mutex* MallocHooksState::malloc_hook_mutex_ = new Mutex();
+ThreadId MallocHooksState::malloc_hook_mutex_owner_ =
+    OSThread::kInvalidThreadId;
 
 // Memory allocation state information.
 intptr_t MallocHooksState::allocation_count_ = 0;
@@ -206,10 +184,10 @@ void MallocHooks::InitOnce() {
   if (!FLAG_enable_malloc_hooks) {
     return;
   }
-  MutexLocker ml(MallocHooksState::malloc_hook_mutex());
+  MallocLocker ml(MallocHooksState::malloc_hook_mutex(),
+                  MallocHooksState::malloc_hook_mutex_owner());
   ASSERT(!MallocHooksState::Active());
 
-  MallocHookScope::InitMallocHookFlag();
   MallocHooksState::Init();
 
   // Register malloc hooks.
@@ -225,7 +203,8 @@ void MallocHooks::TearDown() {
   if (!FLAG_enable_malloc_hooks) {
     return;
   }
-  MutexLocker ml(MallocHooksState::malloc_hook_mutex());
+  MallocLocker ml(MallocHooksState::malloc_hook_mutex(),
+                  MallocHooksState::malloc_hook_mutex_owner());
   ASSERT(MallocHooksState::Active());
 
   // Remove malloc hooks.
@@ -236,7 +215,6 @@ void MallocHooks::TearDown() {
   ASSERT(success);
 
   MallocHooksState::TearDown();
-  MallocHookScope::DestroyMallocHookFlag();
 }
 
 
@@ -244,7 +222,8 @@ void MallocHooks::ResetStats() {
   if (!FLAG_enable_malloc_hooks) {
     return;
   }
-  MutexLocker ml(MallocHooksState::malloc_hook_mutex());
+  MallocLocker ml(MallocHooksState::malloc_hook_mutex(),
+                  MallocHooksState::malloc_hook_mutex_owner());
   if (MallocHooksState::Active()) {
     MallocHooksState::ResetStats();
   }
@@ -271,7 +250,8 @@ void MallocHooks::PrintToJSONObject(JSONObject* jsobj) {
   // to acquire the lock recursively so we extract the values first
   // and then add the JSON properties.
   {
-    MutexLocker ml(MallocHooksState::malloc_hook_mutex());
+    MallocLocker ml(MallocHooksState::malloc_hook_mutex(),
+                    MallocHooksState::malloc_hook_mutex_owner());
     if (Active()) {
       allocated_memory = MallocHooksState::heap_allocated_memory_in_bytes();
       allocation_count = MallocHooksState::allocation_count();
@@ -289,7 +269,8 @@ intptr_t MallocHooks::allocation_count() {
   if (!FLAG_enable_malloc_hooks) {
     return 0;
   }
-  MutexLocker ml(MallocHooksState::malloc_hook_mutex());
+  MallocLocker ml(MallocHooksState::malloc_hook_mutex(),
+                  MallocHooksState::malloc_hook_mutex_owner());
   return MallocHooksState::allocation_count();
 }
 
@@ -298,22 +279,22 @@ intptr_t MallocHooks::heap_allocated_memory_in_bytes() {
   if (!FLAG_enable_malloc_hooks) {
     return 0;
   }
-  MutexLocker ml(MallocHooksState::malloc_hook_mutex());
+  MallocLocker ml(MallocHooksState::malloc_hook_mutex(),
+                  MallocHooksState::malloc_hook_mutex_owner());
   return MallocHooksState::heap_allocated_memory_in_bytes();
 }
 
 
 void MallocHooksState::RecordAllocHook(const void* ptr, size_t size) {
-  if (MallocHookScope::IsInHook() || !MallocHooksState::IsOriginalProcess()) {
+  if (MallocHooksState::IsLockHeldByCurrentThread() ||
+      !MallocHooksState::IsOriginalProcess()) {
     return;
   }
 
-  MutexLocker ml(MallocHooksState::malloc_hook_mutex());
+  MallocLocker ml(MallocHooksState::malloc_hook_mutex(),
+                  MallocHooksState::malloc_hook_mutex_owner());
   // Now that we hold the lock, check to make sure everything is still active.
   if ((ptr != NULL) && MallocHooksState::Active()) {
-    // Set the malloc hook flag to avoid calling hooks again if memory is
-    // allocated/freed below.
-    MallocHookScope mhs;
     MallocHooksState::IncrementHeapAllocatedMemoryInBytes(size);
     MallocHooksState::address_map()->Insert(ptr, size);
   }
@@ -321,16 +302,15 @@ void MallocHooksState::RecordAllocHook(const void* ptr, size_t size) {
 
 
 void MallocHooksState::RecordFreeHook(const void* ptr) {
-  if (MallocHookScope::IsInHook() || !MallocHooksState::IsOriginalProcess()) {
+  if (MallocHooksState::IsLockHeldByCurrentThread() ||
+      !MallocHooksState::IsOriginalProcess()) {
     return;
   }
 
-  MutexLocker ml(MallocHooksState::malloc_hook_mutex());
+  MallocLocker ml(MallocHooksState::malloc_hook_mutex(),
+                  MallocHooksState::malloc_hook_mutex_owner());
   // Now that we hold the lock, check to make sure everything is still active.
   if ((ptr != NULL) && MallocHooksState::Active()) {
-    // Set the malloc hook flag to avoid calling hooks again if memory is
-    // allocated/freed below.
-    MallocHookScope mhs;
     intptr_t size = 0;
     if (MallocHooksState::address_map()->Lookup(ptr, &size)) {
       MallocHooksState::DecrementHeapAllocatedMemoryInBytes(size);