platform-linux.cc.svn-base

Google浏览器V8内核代码

    char* start_of_path = index(buffer, '/');
    // There may be no filename in this line.  Skip to next.
    if (start_of_path == NULL) continue;
    buffer[bytes_read] = 0;
    LOG(SharedLibraryEvent(start_of_path, start, end));
  }
  close(fd);
#endif
}


int OS::StackWalk(OS::StackFrame* frames, int frames_size) {
  void** addresses = NewArray<void*>(frames_size);

  int frames_count = backtrace(addresses, frames_size);

  char** symbols;
  symbols = backtrace_symbols(addresses, frames_count);
  if (symbols == NULL) {
    DeleteArray(addresses);
    return kStackWalkError;
  }

  for (int i = 0; i < frames_count; i++) {
    frames[i].address = addresses[i];
    // Format a text representation of the frame based on the information
    // available.
    SNPrintF(MutableCStrVector(frames[i].text, kStackWalkMaxTextLen),
             "%s",
             symbols[i]);
    // Make sure line termination is in place.
    frames[i].text[kStackWalkMaxTextLen - 1] = '\0';
  }

  DeleteArray(addresses);
  free(symbols);

  return frames_count;
}


// Constants used for mmap.
static const int kMmapFd = -1;
static const int kMmapFdOffset = 0;


VirtualMemory::VirtualMemory(size_t size) {
  address_ = mmap(NULL, size, PROT_NONE,
                  MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE,
                  kMmapFd, kMmapFdOffset);
  size_ = size;
}


VirtualMemory::~VirtualMemory() {
  if (IsReserved()) {
    if (0 == munmap(address(), size())) address_ = MAP_FAILED;
  }
}


bool VirtualMemory::IsReserved() {
  return address_ != MAP_FAILED;
}


bool VirtualMemory::Commit(void* address, size_t size, bool executable) {
  int prot = PROT_READ | PROT_WRITE | (executable ? PROT_EXEC : 0);
  if (MAP_FAILED == mmap(address, size, prot,
                         MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
                         kMmapFd, kMmapFdOffset)) {
    return false;
  }

  UpdateAllocatedSpaceLimits(address, size);
  return true;
}


bool VirtualMemory::Uncommit(void* address, size_t size) {
  return mmap(address, size, PROT_NONE,
              MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE,
              kMmapFd, kMmapFdOffset) != MAP_FAILED;
}


class ThreadHandle::PlatformData : public Malloced {
 public:
  explicit PlatformData(ThreadHandle::Kind kind) {
    Initialize(kind);
  }

  void Initialize(ThreadHandle::Kind kind) {
    switch (kind) {
      case ThreadHandle::SELF: thread_ = pthread_self(); break;
      case ThreadHandle::INVALID: thread_ = kNoThread; break;
    }
  }
  pthread_t thread_;  // Thread handle for pthread.
};


ThreadHandle::ThreadHandle(Kind kind) {
  data_ = new PlatformData(kind);
}


void ThreadHandle::Initialize(ThreadHandle::Kind kind) {
  data_->Initialize(kind);
}


ThreadHandle::~ThreadHandle() {
  delete data_;
}


bool ThreadHandle::IsSelf() const {
  return pthread_equal(data_->thread_, pthread_self());
}


bool ThreadHandle::IsValid() const {
  return data_->thread_ != kNoThread;
}


Thread::Thread() : ThreadHandle(ThreadHandle::INVALID) {
}


Thread::~Thread() {
}


static void* ThreadEntry(void* arg) {
  Thread* thread = reinterpret_cast<Thread*>(arg);
  // This is also initialized by the first argument to pthread_create() but we
  // don't know which thread will run first (the original thread or the new
  // one) so we initialize it here too.
  thread->thread_handle_data()->thread_ = pthread_self();
  ASSERT(thread->IsValid());
  thread->Run();
  return NULL;
}


void Thread::Start() {
  pthread_create(&thread_handle_data()->thread_, NULL, ThreadEntry, this);
  ASSERT(IsValid());
}


void Thread::Join() {
  pthread_join(thread_handle_data()->thread_, NULL);
}


Thread::LocalStorageKey Thread::CreateThreadLocalKey() {
  pthread_key_t key;
  int result = pthread_key_create(&key, NULL);
  USE(result);
  ASSERT(result == 0);
  return static_cast<LocalStorageKey>(key);
}


void Thread::DeleteThreadLocalKey(LocalStorageKey key) {
  pthread_key_t pthread_key = static_cast<pthread_key_t>(key);
  int result = pthread_key_delete(pthread_key);
  USE(result);
  ASSERT(result == 0);
}


void* Thread::GetThreadLocal(LocalStorageKey key) {
  pthread_key_t pthread_key = static_cast<pthread_key_t>(key);
  return pthread_getspecific(pthread_key);
}


void Thread::SetThreadLocal(LocalStorageKey key, void* value) {
  pthread_key_t pthread_key = static_cast<pthread_key_t>(key);
  pthread_setspecific(pthread_key, value);
}


void Thread::YieldCPU() {
  sched_yield();
}


class LinuxMutex : public Mutex {
 public:

  LinuxMutex() {
    pthread_mutexattr_t attrs;
    int result = pthread_mutexattr_init(&attrs);
    ASSERT(result == 0);
    result = pthread_mutexattr_settype(&attrs, PTHREAD_MUTEX_RECURSIVE);
    ASSERT(result == 0);
    result = pthread_mutex_init(&mutex_, &attrs);
    ASSERT(result == 0);
  }

  virtual ~LinuxMutex() { pthread_mutex_destroy(&mutex_); }

  virtual int Lock() {
    int result = pthread_mutex_lock(&mutex_);
    return result;
  }

  virtual int Unlock() {
    int result = pthread_mutex_unlock(&mutex_);
    return result;
  }

 private:
  pthread_mutex_t mutex_;   // Pthread mutex for POSIX platforms.
};


Mutex* OS::CreateMutex() {
  return new LinuxMutex();
}


class LinuxSemaphore : public Semaphore {
 public:
  explicit LinuxSemaphore(int count) {  sem_init(&sem_, 0, count); }
  virtual ~LinuxSemaphore() { sem_destroy(&sem_); }

  virtual void Wait();
  virtual void Signal() { sem_post(&sem_); }
 private:
  sem_t sem_;
};

void LinuxSemaphore::Wait() {
  while (true) {
    int result = sem_wait(&sem_);
    if (result == 0) return;  // Successfully got semaphore.
    CHECK(result == -1 && errno == EINTR);  // Signal caused spurious wakeup.
  }
}

Semaphore* OS::CreateSemaphore(int count) {
  return new LinuxSemaphore(count);
}

#ifdef ENABLE_LOGGING_AND_PROFILING

static Sampler* active_sampler_ = NULL;

static void ProfilerSignalHandler(int signal, siginfo_t* info, void* context) {
  USE(info);
  if (signal != SIGPROF) return;
  if (active_sampler_ == NULL) return;

  TickSample sample;

  // If profiling, we extract the current pc and sp.
  if (active_sampler_->IsProfiling()) {
    // Extracting the sample from the context is extremely machine dependent.
    ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(context);
    mcontext_t& mcontext = ucontext->uc_mcontext;
#if defined (__arm__) || defined(__thumb__)
    sample.pc = mcontext.gregs[R15];
    sample.sp = mcontext.gregs[R13];
#else
    sample.pc = mcontext.gregs[REG_EIP];
    sample.sp = mcontext.gregs[REG_ESP];
#endif
  }

  // We always sample the VM state.
  sample.state = Logger::state();

  active_sampler_->Tick(&sample);
}


class Sampler::PlatformData : public Malloced {
 public:
  PlatformData() {
    signal_handler_installed_ = false;
  }

  bool signal_handler_installed_;
  struct sigaction old_signal_handler_;
  struct itimerval old_timer_value_;
};


Sampler::Sampler(int interval, bool profiling)
    : interval_(interval), profiling_(profiling), active_(false) {
  data_ = new PlatformData();
}


Sampler::~Sampler() {
  delete data_;
}


void Sampler::Start() {
  // There can only be one active sampler at the time on POSIX
  // platforms.
  if (active_sampler_ != NULL) return;

  // Request profiling signals.
  struct sigaction sa;
  sa.sa_sigaction = ProfilerSignalHandler;
  sigemptyset(&sa.sa_mask);
  sa.sa_flags = SA_SIGINFO;
  if (sigaction(SIGPROF, &sa, &data_->old_signal_handler_) != 0) return;
  data_->signal_handler_installed_ = true;

  // Set the itimer to generate a tick for each interval.
  itimerval itimer;
  itimer.it_interval.tv_sec = interval_ / 1000;
  itimer.it_interval.tv_usec = (interval_ % 1000) * 1000;
  itimer.it_value.tv_sec = itimer.it_interval.tv_sec;
  itimer.it_value.tv_usec = itimer.it_interval.tv_usec;
  setitimer(ITIMER_PROF, &itimer, &data_->old_timer_value_);

  // Set this sampler as the active sampler.
  active_sampler_ = this;
  active_ = true;
}


void Sampler::Stop() {
  // Restore old signal handler
  if (data_->signal_handler_installed_) {
    setitimer(ITIMER_PROF, &data_->old_timer_value_, NULL);
    sigaction(SIGPROF, &data_->old_signal_handler_, 0);
    data_->signal_handler_installed_ = false;
  }

  // This sampler is no longer the active sampler.
  active_sampler_ = NULL;
  active_ = false;
}

#endif  // ENABLE_LOGGING_AND_PROFILING

} }  // namespace v8::internal