libsampler: Cleanup SamplerManager

src/libsampler/v8-sampler.cc

 // Copyright 2016 the V8 project 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 "src/libsampler/v8-sampler.h"
 
 #if V8_OS_POSIX && !V8_OS_CYGWIN
 
 #define USE_SIGNALS
 
@@ skipping 145 matching lines @@
 
 
 namespace v8 {
 namespace sampler {
 
 namespace {
 
 #if defined(USE_SIGNALS)
 typedef std::vector<Sampler*> SamplerList;
 typedef SamplerList::iterator SamplerListIterator;
+typedef base::AtomicValue<bool> AtomicMutex;
 
 class AtomicGuard {
  public:
-  explicit AtomicGuard(base::AtomicValue<int>* atomic, bool is_block = true)
-      : atomic_(atomic),
-        is_success_(false) {
+  explicit AtomicGuard(AtomicMutex* atomic, bool is_blocking = true)
+      : atomic_(atomic), is_success_(false) {
     do {
       // Use Acquire_Load to gain mutual exclusion.
       USE(atomic_->Value());
-      is_success_ = atomic_->TrySetValue(0, 1);
-    } while (is_block && !is_success_);
+      is_success_ = atomic_->TrySetValue(false, true);
+    } while (is_blocking && !is_success_);
   }
 
-  bool is_success() { return is_success_; }
+  bool is_success() const { return is_success_; }
 
   ~AtomicGuard() {
-    if (is_success_) {
-      atomic_->SetValue(0);
-    }
-    atomic_ = NULL;
+    if (!is_success_) return;
+    atomic_->SetValue(false);
   }
 
  private:
-  base::AtomicValue<int>* atomic_;
+  AtomicMutex* const atomic_;
   bool is_success_;
 };
 
-
 // Returns key for hash map.
 void* ThreadKey(pthread_t thread_id) {
   return reinterpret_cast<void*>(thread_id);
 }
 
-
 // Returns hash value for hash map.
 uint32_t ThreadHash(pthread_t thread_id) {
 #if V8_OS_MACOSX
   return static_cast<uint32_t>(reinterpret_cast<intptr_t>(thread_id));
 #else
   return static_cast<uint32_t>(thread_id);
 #endif
 }
 
 #endif  // USE_SIGNALS
 
 }  // namespace
 
 #if defined(USE_SIGNALS)
 
 class Sampler::PlatformData {
  public:
   PlatformData() : vm_tid_(pthread_self()) {}
   pthread_t vm_tid() const { return vm_tid_; }
 
  private:
   pthread_t vm_tid_;
 };
 
-
 class SamplerManager {
  public:
-  static void AddSampler(Sampler* sampler) {
+  SamplerManager() : sampler_map_(HashMap::PointersMatch) {}
+
+  void AddSampler(Sampler* sampler) {
     AtomicGuard atomic_guard(&samplers_access_counter_);
     DCHECK(sampler->IsActive() || !sampler->IsRegistered());
     // Add sampler into map if needed.
     pthread_t thread_id = sampler->platform_data()->vm_tid();
-    HashMap::Entry* entry =
-        sampler_map_.Pointer()->LookupOrInsert(ThreadKey(thread_id),
-                                               ThreadHash(thread_id));
-    DCHECK(entry != NULL);
-    if (entry->value == NULL) {
+    HashMap::Entry* entry = sampler_map_.LookupOrInsert(ThreadKey(thread_id),
+                                                        ThreadHash(thread_id));
+    DCHECK(entry != nullptr);
+    if (entry->value == nullptr) {
       SamplerList* samplers = new SamplerList();
       samplers->push_back(sampler);
       entry->value = samplers;
     } else {
       SamplerList* samplers = reinterpret_cast<SamplerList*>(entry->value);
       bool exists = false;
       for (SamplerListIterator iter = samplers->begin();
            iter != samplers->end(); ++iter) {
         if (*iter == sampler) {
           exists = true;
           break;
         }
       }
       if (!exists) {
         samplers->push_back(sampler);
       }
     }
   }
 
-  static void RemoveSampler(Sampler* sampler) {
+  void RemoveSampler(Sampler* sampler) {
     AtomicGuard atomic_guard(&samplers_access_counter_);
     DCHECK(sampler->IsActive() || sampler->IsRegistered());
     // Remove sampler from map.
     pthread_t thread_id = sampler->platform_data()->vm_tid();
     void* thread_key = ThreadKey(thread_id);
     uint32_t thread_hash = ThreadHash(thread_id);
-    HashMap::Entry* entry = sampler_map_.Get().Lookup(thread_key, thread_hash);
-    DCHECK(entry != NULL);
+    HashMap::Entry* entry = sampler_map_.Lookup(thread_key, thread_hash);
+    DCHECK(entry != nullptr);
     SamplerList* samplers = reinterpret_cast<SamplerList*>(entry->value);
     for (SamplerListIterator iter = samplers->begin(); iter != samplers->end();
          ++iter) {
       if (*iter == sampler) {
         samplers->erase(iter);
         break;
       }
     }
     if (samplers->empty()) {
-      sampler_map_.Pointer()->Remove(thread_key, thread_hash);
+      sampler_map_.Remove(thread_key, thread_hash);
       delete samplers;
     }
   }
 
+#if defined(USE_SIGNALS)
+  void DoSample(const v8::RegisterState& state) {
+    AtomicGuard atomic_guard(&SamplerManager::samplers_access_counter_, false);
+    if (!atomic_guard.is_success()) return;
+    pthread_t thread_id = pthread_self();
+    HashMap::Entry* entry =
+        sampler_map_.Lookup(ThreadKey(thread_id), ThreadHash(thread_id));
+    if (!entry) return;
+    SamplerList& samplers = *static_cast<SamplerList*>(entry->value);
+
+    for (int i = 0; i < samplers.size(); ++i) {
+      Sampler* sampler = samplers[i];
+      Isolate* isolate = sampler->isolate();
+      // We require a fully initialized and entered isolate.
+      if (isolate == nullptr || !isolate->IsInUse()) continue;
+      if (v8::Locker::IsActive() && !Locker::IsLocked(isolate)) continue;
+      sampler->SampleStack(state);
+    }
+  }
+#endif
+
+  static SamplerManager* instance() { return instance_.Pointer(); }
+
  private:
-  struct HashMapCreateTrait {
-    static void Construct(HashMap* allocated_ptr) {
-      new (allocated_ptr) HashMap(HashMap::PointersMatch);
-    }
-  };
-  friend class SignalHandler;
-  static base::LazyInstance<HashMap, HashMapCreateTrait>::type
-      sampler_map_;
-  static base::AtomicValue<int> samplers_access_counter_;
+  HashMap sampler_map_;
+  static AtomicMutex samplers_access_counter_;
+  static base::LazyInstance<SamplerManager>::type instance_;
 };
 
-base::LazyInstance<HashMap, SamplerManager::HashMapCreateTrait>::type
-    SamplerManager::sampler_map_ = LAZY_INSTANCE_INITIALIZER;
-base::AtomicValue<int> SamplerManager::samplers_access_counter_(0);
-
+AtomicMutex SamplerManager::samplers_access_counter_;
+base::LazyInstance<SamplerManager>::type SamplerManager::instance_ =
+    LAZY_INSTANCE_INITIALIZER;
 
 #elif V8_OS_WIN || V8_OS_CYGWIN
 
 // ----------------------------------------------------------------------------
 // Win32 profiler support. On Cygwin we use the same sampler implementation as
 // on Win32.
 
 class Sampler::PlatformData {
  public:
   // Get a handle to the calling thread. This is the thread that we are
   // going to profile. We need to make a copy of the handle because we are
   // going to use it in the sampler thread. Using GetThreadHandle() will
   // not work in this case. We're using OpenThread because DuplicateHandle
   // for some reason doesn't work in Chrome's sandbox.
   PlatformData()
       : profiled_thread_(OpenThread(THREAD_GET_CONTEXT |
                                     THREAD_SUSPEND_RESUME |
                                     THREAD_QUERY_INFORMATION,
                                     false,
                                     GetCurrentThreadId())) {}
 
   ~PlatformData() {
-    if (profiled_thread_ != NULL) {
+    if (profiled_thread_ != nullptr) {
       CloseHandle(profiled_thread_);
-      profiled_thread_ = NULL;
+      profiled_thread_ = nullptr;
     }
   }
 
   HANDLE profiled_thread() { return profiled_thread_; }
 
  private:
   HANDLE profiled_thread_;
 };
 #endif  // USE_SIGNALS
 
 
 #if defined(USE_SIGNALS)
 class SignalHandler {
  public:
   static void SetUp() { if (!mutex_) mutex_ = new base::Mutex(); }
-  static void TearDown() { delete mutex_; mutex_ = NULL; }
+  static void TearDown() {
+    delete mutex_;
+    mutex_ = nullptr;
+  }
 
   static void IncreaseSamplerCount() {
     base::LockGuard<base::Mutex> lock_guard(mutex_);
     if (++client_count_ == 1) Install();
   }
 
   static void DecreaseSamplerCount() {
     base::LockGuard<base::Mutex> lock_guard(mutex_);
     if (--client_count_ == 0) Restore();
   }
@@ skipping 32 matching lines @@
   static void FillRegisterState(void* context, RegisterState* regs);
   static void HandleProfilerSignal(int signal, siginfo_t* info, void* context);
 #endif
   // Protects the process wide state below.
   static base::Mutex* mutex_;
   static int client_count_;
   static bool signal_handler_installed_;
   static struct sigaction old_signal_handler_;
 };
 
-
-base::Mutex* SignalHandler::mutex_ = NULL;
+base::Mutex* SignalHandler::mutex_ = nullptr;
 int SignalHandler::client_count_ = 0;
 struct sigaction SignalHandler::old_signal_handler_;
 bool SignalHandler::signal_handler_installed_ = false;
 
 
 // As Native Client does not support signal handling, profiling is disabled.
 #if !V8_OS_NACL
 void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
                                          void* context) {
   USE(info);
   if (signal != SIGPROF) return;
-  AtomicGuard atomic_guard(&SamplerManager::samplers_access_counter_, false);
-  if (!atomic_guard.is_success()) return;
-  pthread_t thread_id = pthread_self();
-  HashMap::Entry* entry =
-      SamplerManager::sampler_map_.Pointer()->Lookup(ThreadKey(thread_id),
-                                                     ThreadHash(thread_id));
-  if (entry == NULL) return;
-  SamplerList* samplers = reinterpret_cast<SamplerList*>(entry->value);
-
   v8::RegisterState state;
   FillRegisterState(context, &state);
-
-  for (int i = 0; i < samplers->size(); ++i) {
-    Sampler* sampler = (*samplers)[i];
-    Isolate* isolate = sampler->isolate();
-
-    // We require a fully initialized and entered isolate.
-    if (isolate == NULL || !isolate->IsInUse()) return;
-
-    if (v8::Locker::IsActive() && !Locker::IsLocked(isolate)) return;
-
-    sampler->SampleStack(state);
-  }
+  SamplerManager::instance()->DoSample(state);
 }
 
 void SignalHandler::FillRegisterState(void* context, RegisterState* state) {
   // Extracting the sample from the context is extremely machine dependent.
   ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(context);
 #if !(V8_OS_OPENBSD || (V8_OS_LINUX && (V8_HOST_ARCH_PPC || V8_HOST_ARCH_S390)))
   mcontext_t& mcontext = ucontext->uc_mcontext;
 #endif
 #if V8_OS_LINUX
 #if V8_HOST_ARCH_IA32
@@ skipping 151 matching lines @@
       has_processing_thread_(false),
       active_(false),
       registered_(false) {
   data_ = new PlatformData;
 }
 
 Sampler::~Sampler() {
   DCHECK(!IsActive());
 #if defined(USE_SIGNALS)
   if (IsRegistered()) {
-    SamplerManager::RemoveSampler(this);
+    SamplerManager::instance()->RemoveSampler(this);
   }
 #endif
   delete data_;
 }
 
 void Sampler::Start() {
   DCHECK(!IsActive());
   SetActive(true);
 #if defined(USE_SIGNALS)
-  SamplerManager::AddSampler(this);
+  SamplerManager::instance()->AddSampler(this);
 #endif
 }
 
 
 void Sampler::Stop() {
 #if defined(USE_SIGNALS)
-  SamplerManager::RemoveSampler(this);
+  SamplerManager::instance()->RemoveSampler(this);
 #endif
   DCHECK(IsActive());
   SetActive(false);
   SetRegistered(false);
 }
 
 
 void Sampler::IncreaseProfilingDepth() {
   base::NoBarrier_AtomicIncrement(&profiling_, 1);
 #if defined(USE_SIGNALS)
   SignalHandler::IncreaseSamplerCount();
 #endif
 }
 
 
 void Sampler::DecreaseProfilingDepth() {
 #if defined(USE_SIGNALS)
   SignalHandler::DecreaseSamplerCount();
 #endif
   base::NoBarrier_AtomicIncrement(&profiling_, -1);
 }
 
 
 #if defined(USE_SIGNALS)
 
 void Sampler::DoSample() {
   if (!SignalHandler::Installed()) return;
   if (!IsActive() && !IsRegistered()) {
-    SamplerManager::AddSampler(this);
+    SamplerManager::instance()->AddSampler(this);
     SetRegistered(true);
   }
   pthread_kill(platform_data()->vm_tid(), SIGPROF);
 }
 
 #elif V8_OS_WIN || V8_OS_CYGWIN
 
 void Sampler::DoSample() {
   HANDLE profiled_thread = platform_data()->profiled_thread();
-  if (profiled_thread == NULL) return;
+  if (profiled_thread == nullptr) return;
 
   const DWORD kSuspendFailed = static_cast<DWORD>(-1);
   if (SuspendThread(profiled_thread) == kSuspendFailed) return;
 
   // Context used for sampling the register state of the profiled thread.
   CONTEXT context;
   memset(&context, 0, sizeof(context));
   context.ContextFlags = CONTEXT_FULL;
   if (GetThreadContext(profiled_thread, &context) != 0) {
     v8::RegisterState state;
 #if V8_HOST_ARCH_X64
     state.pc = reinterpret_cast<void*>(context.Rip);
     state.sp = reinterpret_cast<void*>(context.Rsp);
     state.fp = reinterpret_cast<void*>(context.Rbp);
 #else
     state.pc = reinterpret_cast<void*>(context.Eip);
     state.sp = reinterpret_cast<void*>(context.Esp);
     state.fp = reinterpret_cast<void*>(context.Ebp);
 #endif
     SampleStack(state);
   }
   ResumeThread(profiled_thread);
 }
 
 #endif  // USE_SIGNALS
 
 }  // namespace sampler
 }  // namespace v8