text: // Copyright 2012 the V8 project authors. All rights reserved.
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  //       notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  //       copyright notice, this list of conditions and the following
  //       disclaimer in the documentation and/or other materials provided
  //       with the distribution.
  //     * Neither the name of Google Inc. nor the names of its
  //       contributors may be used to endorse or promote products derived
  //       from this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  // Platform specific code for Cygwin goes here. For the POSIX comaptible parts
  // the implementation is in platform-posix.cc.
  
  #include <errno.h>
  #include <pthread.h>
  #include <semaphore.h>
  #include <stdarg.h>
  #include <strings.h>    // index
  #include <sys/time.h>
  #include <sys/mman.h>   // mmap & munmap
  #include <unistd.h>     // sysconf
  
  #undef MAP_TYPE
  
  #include "v8.h"
  
  #include "platform.h"
  #include "v8threads.h"
  #include "vm-state-inl.h"
  #include "win32-headers.h"
  
  namespace v8 {
  namespace internal {
  
  // 0 is never a valid thread id
  static const pthread_t kNoThread = (pthread_t) 0;
  
  
  double ceiling(double x) {
    return ceil(x);
  }
  
  
  static Mutex* limit_mutex = NULL;
  
  
  void OS::SetUp() {
    // Seed the random number generator.
    // Convert the current time to a 64-bit integer first, before converting it
    // to an unsigned. Going directly can cause an overflow and the seed to be
    // set to all ones. The seed will be identical for different instances that
    // call this setup code within the same millisecond.
    uint64_t seed = static_cast<uint64_t>(TimeCurrentMillis());
    srandom(static_cast<unsigned int>(seed));
    limit_mutex = CreateMutex();
  }
  
  
  uint64_t OS::CpuFeaturesImpliedByPlatform() {
    return 0;  // Nothing special about Cygwin.
  }
  
  
  int OS::ActivationFrameAlignment() {
    // With gcc 4.4 the tree vectorization optimizer can generate code
    // that requires 16 byte alignment such as movdqa on x86.
    return 16;
  }
  
  
  void OS::ReleaseStore(volatile AtomicWord* ptr, AtomicWord value) {
    __asm__ __volatile__("" : : : "memory");
    // An x86 store acts as a release barrier.
    *ptr = value;
  }
  
  const char* OS::LocalTimezone(double time) {
    if (isnan(time)) return "";
    time_t tv = static_cast<time_t>(floor(time/msPerSecond));
    struct tm* t = localtime(&tv);
    if (NULL == t) return "";
    return tzname[0];  // The location of the timezone string on Cygwin.
  }
  
  
  double OS::LocalTimeOffset() {
    // On Cygwin, struct tm does not contain a tm_gmtoff field.
    time_t utc = time(NULL);
    ASSERT(utc != -1);
    struct tm* loc = localtime(&utc);
    ASSERT(loc != NULL);
    // time - localtime includes any daylight savings offset, so subtract it.
    return static_cast<double>((mktime(loc) - utc) * msPerSecond -
                               (loc->tm_isdst > 0 ? 3600 * msPerSecond : 0));
  }
  
  
  // We keep the lowest and highest addresses mapped as a quick way of
  // determining that pointers are outside the heap (used mostly in assertions
  // and verification).  The estimate is conservative, i.e., not all addresses in
  // 'allocated' space are actually allocated to our heap.  The range is
  // [lowest, highest), inclusive on the low and and exclusive on the high end.
  static void* lowest_ever_allocated = reinterpret_cast<void*>(-1);
  static void* highest_ever_allocated = reinterpret_cast<void*>(0);
  
  
  static void UpdateAllocatedSpaceLimits(void* address, int size) {
    ASSERT(limit_mutex != NULL);
    ScopedLock lock(limit_mutex);
  
    lowest_ever_allocated = Min(lowest_ever_allocated, address);
    highest_ever_allocated =
        Max(highest_ever_allocated,
            reinterpret_cast<void*>(reinterpret_cast<char*>(address) + size));
  }
  
  
  bool OS::IsOutsideAllocatedSpace(void* address) {
    return address < lowest_ever_allocated || address >= highest_ever_allocated;
  }
  
  
  size_t OS::AllocateAlignment() {
    return sysconf(_SC_PAGESIZE);
  }
  
  
  void* OS::Allocate(const size_t requested,
                     size_t* allocated,
                     bool is_executable) {
    const size_t msize = RoundUp(requested, sysconf(_SC_PAGESIZE));
    int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
    void* mbase = mmap(NULL, msize, prot, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
    if (mbase == MAP_FAILED) {
      LOG(ISOLATE, StringEvent("OS::Allocate", "mmap failed"));
      return NULL;
    }
    *allocated = msize;
    UpdateAllocatedSpaceLimits(mbase, msize);
    return mbase;
  }
  
  
  void OS::Free(void* address, const size_t size) {
    // TODO(1240712): munmap has a return value which is ignored here.
    int result = munmap(address, size);
    USE(result);
    ASSERT(result == 0);
  }
  
  
  void OS::ProtectCode(void* address, const size_t size) {
    DWORD old_protect;
    VirtualProtect(address, size, PAGE_EXECUTE_READ, &old_protect);
  }
  
  
  void OS::Guard(void* address, const size_t size) {
    DWORD oldprotect;
    VirtualProtect(address, size, PAGE_READONLY | PAGE_GUARD, &oldprotect);
  }
  
  
  void OS::Sleep(int milliseconds) {
    unsigned int ms = static_cast<unsigned int>(milliseconds);
    usleep(1000 * ms);
  }
  
  
  void OS::Abort() {
    // Redirect to std abort to signal abnormal program termination.
    abort();
  }
  
  
  void OS::DebugBreak() {
    asm("int $3");
  }
  
  
  class PosixMemoryMappedFile : public OS::MemoryMappedFile {
   public:
    PosixMemoryMappedFile(FILE* file, void* memory, int size)
      : file_(file), memory_(memory), size_(size) { }
    virtual ~PosixMemoryMappedFile();
    virtual void* memory() { return memory_; }
    virtual int size() { return size_; }
   private:
    FILE* file_;
    void* memory_;
    int size_;
  };
  
  
  OS::MemoryMappedFile* OS::MemoryMappedFile::open(const char* name) {
    FILE* file = fopen(name, "r+");
    if (file == NULL) return NULL;
  
    fseek(file, 0, SEEK_END);
    int size = ftell(file);
  
    void* memory =
        mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, fileno(file), 0);
    return new PosixMemoryMappedFile(file, memory, size);
  }
  
  
  OS::MemoryMappedFile* OS::MemoryMappedFile::create(const char* name, int size,
      void* initial) {
    FILE* file = fopen(name, "w+");
    if (file == NULL) return NULL;
    int result = fwrite(initial, size, 1, file);
    if (result < 1) {
      fclose(file);
      return NULL;
    }
    void* memory =
        mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, fileno(file), 0);
    return new PosixMemoryMappedFile(file, memory, size);
  }
  
  
  PosixMemoryMappedFile::~PosixMemoryMappedFile() {
    if (memory_) munmap(memory_, size_);
    fclose(file_);
  }
  
  
  void OS::LogSharedLibraryAddresses() {
    // This function assumes that the layout of the file is as follows:
    // hex_start_addr-hex_end_addr rwxp <unused data> [binary_file_name]
    // If we encounter an unexpected situation we abort scanning further entries.
    FILE* fp = fopen("/proc/self/maps", "r");
    if (fp == NULL) return;
  
    // Allocate enough room to be able to store a full file name.
    const int kLibNameLen = FILENAME_MAX + 1;
    char* lib_name = reinterpret_cast<char*>(malloc(kLibNameLen));
  
    i::Isolate* isolate = ISOLATE;
    // This loop will terminate once the scanning hits an EOF.
    while (true) {
      uintptr_t start, end;
      char attr_r, attr_w, attr_x, attr_p;
      // Parse the addresses and permission bits at the beginning of the line.
      if (fscanf(fp, "%" V8PRIxPTR "-%" V8PRIxPTR, &start, &end) != 2) break;
      if (fscanf(fp, " %c%c%c%c", &attr_r, &attr_w, &attr_x, &attr_p) != 4) break;
  
      int c;
      if (attr_r == 'r' && attr_w != 'w' && attr_x == 'x') {
        // Found a read-only executable entry. Skip characters until we reach
        // the beginning of the filename or the end of the line.
        do {
          c = getc(fp);
        } while ((c != EOF) && (c != '\n') && (c != '/'));
        if (c == EOF) break;  // EOF: Was unexpected, just exit.
  
        // Process the filename if found.
        if (c == '/') {
          ungetc(c, fp);  // Push the '/' back into the stream to be read below.
  
          // Read to the end of the line. Exit if the read fails.
          if (fgets(lib_name, kLibNameLen, fp) == NULL) break;
  
          // Drop the newline character read by fgets. We do not need to check
          // for a zero-length string because we know that we at least read the
          // '/' character.
          lib_name[strlen(lib_name) - 1] = '\0';
        } else {
          // No library name found, just record the raw address range.
          snprintf(lib_name, kLibNameLen,
                   "%08" V8PRIxPTR "-%08" V8PRIxPTR, start, end);
        }
        LOG(isolate, SharedLibraryEvent(lib_name, start, end));
      } else {
        // Entry not describing executable data. Skip to end of line to set up
        // reading the next entry.
        do {
          c = getc(fp);
        } while ((c != EOF) && (c != '\n'));
        if (c == EOF) break;
      }
    }
    free(lib_name);
    fclose(fp);
  }
  
  
  void OS::SignalCodeMovingGC() {
    // Nothing to do on Cygwin.
  }
  
  
  int OS::StackWalk(Vector<OS::StackFrame> frames) {
    // Not supported on Cygwin.
    return 0;
  }
  
  
  // The VirtualMemory implementation is taken from platform-win32.cc.
  // The mmap-based virtual memory implementation as it is used on most posix
  // platforms does not work well because Cygwin does not support MAP_FIXED.
  // This causes VirtualMemory::Commit to not always commit the memory region
  // specified.
  
  bool VirtualMemory::IsReserved() {
    return address_ != NULL;
  }
  
  
  VirtualMemory::VirtualMemory(size_t size) {
    address_ = VirtualAlloc(NULL, size, MEM_RESERVE, PAGE_NOACCESS);
    size_ = size;
  }
  
  
  VirtualMemory::~VirtualMemory() {
    if (IsReserved()) {
      if (0 == VirtualFree(address(), 0, MEM_RELEASE)) address_ = NULL;
    }
  }
  
  
  bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) {
    int prot = is_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
    if (NULL == VirtualAlloc(address, size, MEM_COMMIT, prot)) {
      return false;
    }
  
    UpdateAllocatedSpaceLimits(address, static_cast<int>(size));
    return true;
  }
  
  
  bool VirtualMemory::Uncommit(void* address, size_t size) {
    ASSERT(IsReserved());
    return VirtualFree(address, size, MEM_DECOMMIT) != false;
  }
  
  
  bool VirtualMemory::Guard(void* address) {
    if (NULL == VirtualAlloc(address,
                             OS::CommitPageSize(),
                             MEM_COMMIT,
                             PAGE_READONLY | PAGE_GUARD)) {
      return false;
    }
    return true;
  }
  
  
  class Thread::PlatformData : public Malloced {
   public:
    PlatformData() : thread_(kNoThread) {}
    pthread_t thread_;  // Thread handle for pthread.
  };
  
  
  
  
  Thread::Thread(const Options& options)
      : data_(new PlatformData()),
        stack_size_(options.stack_size()) {
    set_name(options.name());
  }
  
  
  Thread::~Thread() {
    delete data_;
  }
  
  
  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->data()->thread_ = pthread_self();
    ASSERT(thread->data()->thread_ != kNoThread);
    thread->Run();
    return NULL;
  }
  
  
  void Thread::set_name(const char* name) {
    strncpy(name_, name, sizeof(name_));
    name_[sizeof(name_) - 1] = '\0';
  }
  
  
  void Thread::Start() {
    pthread_attr_t* attr_ptr = NULL;
    pthread_attr_t attr;
    if (stack_size_ > 0) {
      pthread_attr_init(&attr);
      pthread_attr_setstacksize(&attr, static_cast<size_t>(stack_size_));
      attr_ptr = &attr;
    }
    pthread_create(&data_->thread_, attr_ptr, ThreadEntry, this);
    ASSERT(data_->thread_ != kNoThread);
  }
  
  
  void Thread::Join() {
    pthread_join(data_->thread_, NULL);
  }
  
  
  static inline Thread::LocalStorageKey PthreadKeyToLocalKey(
      pthread_key_t pthread_key) {
    // We need to cast pthread_key_t to Thread::LocalStorageKey in two steps
    // because pthread_key_t is a pointer type on Cygwin. This will probably not
    // work on 64-bit platforms, but Cygwin doesn't support 64-bit anyway.
    STATIC_ASSERT(sizeof(Thread::LocalStorageKey) == sizeof(pthread_key_t));
    intptr_t ptr_key = reinterpret_cast<intptr_t>(pthread_key);
    return static_cast<Thread::LocalStorageKey>(ptr_key);
  }
  
  
  static inline pthread_key_t LocalKeyToPthreadKey(
      Thread::LocalStorageKey local_key) {
    STATIC_ASSERT(sizeof(Thread::LocalStorageKey) == sizeof(pthread_key_t));
    intptr_t ptr_key = static_cast<intptr_t>(local_key);
    return reinterpret_cast<pthread_key_t>(ptr_key);
  }
  
  
  Thread::LocalStorageKey Thread::CreateThreadLocalKey() {
    pthread_key_t key;
    int result = pthread_key_create(&key, NULL);
    USE(result);
    ASSERT(result == 0);
    return PthreadKeyToLocalKey(key);
  }
  
  
  void Thread::DeleteThreadLocalKey(LocalStorageKey key) {
    pthread_key_t pthread_key = LocalKeyToPthreadKey(key);
    int result = pthread_key_delete(pthread_key);
    USE(result);
    ASSERT(result == 0);
  }
  
  
  void* Thread::GetThreadLocal(LocalStorageKey key) {
    pthread_key_t pthread_key = LocalKeyToPthreadKey(key);
    return pthread_getspecific(pthread_key);
  }
  
  
  void Thread::SetThreadLocal(LocalStorageKey key, void* value) {
    pthread_key_t pthread_key = LocalKeyToPthreadKey(key);
    pthread_setspecific(pthread_key, value);
  }
  
  
  void Thread::YieldCPU() {
    sched_yield();
  }
  
  
  class CygwinMutex : public Mutex {
   public:
    CygwinMutex() {
      pthread_mutexattr_t attrs;
      memset(&attrs, 0, sizeof(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 ~CygwinMutex() { 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;
    }
  
    virtual bool TryLock() {
      int result = pthread_mutex_trylock(&mutex_);
      // Return false if the lock is busy and locking failed.
      if (result == EBUSY) {
        return false;
      }
      ASSERT(result == 0);  // Verify no other errors.
      return true;
    }
  
   private:
    pthread_mutex_t mutex_;   // Pthread mutex for POSIX platforms.
  };
  
  
  Mutex* OS::CreateMutex() {
    return new CygwinMutex();
  }
  
  
  class CygwinSemaphore : public Semaphore {
   public:
    explicit CygwinSemaphore(int count) {  sem_init(&sem_, 0, count); }
    virtual ~CygwinSemaphore() { sem_destroy(&sem_); }
  
    virtual void Wait();
    virtual bool Wait(int timeout);
    virtual void Signal() { sem_post(&sem_); }
   private:
    sem_t sem_;
  };
  
  
  void CygwinSemaphore::Wait() {
    while (true) {
      int result = sem_wait(&sem_);
      if (result == 0) return;  // Successfully got semaphore.
      CHECK(result == -1 && errno == EINTR);  // Signal caused spurious wakeup.
    }
  }
  
  
  #ifndef TIMEVAL_TO_TIMESPEC
  #define TIMEVAL_TO_TIMESPEC(tv, ts) do {                            \
      (ts)->tv_sec = (tv)->tv_sec;                                    \
      (ts)->tv_nsec = (tv)->tv_usec * 1000;                           \
  } while (false)
  #endif
  
  
  bool CygwinSemaphore::Wait(int timeout) {
    const long kOneSecondMicros = 1000000;  // NOLINT
  
    // Split timeout into second and nanosecond parts.
    struct timeval delta;
    delta.tv_usec = timeout % kOneSecondMicros;
    delta.tv_sec = timeout / kOneSecondMicros;
  
    struct timeval current_time;
    // Get the current time.
    if (gettimeofday(&current_time, NULL) == -1) {
      return false;
    }
  
    // Calculate time for end of timeout.
    struct timeval end_time;
    timeradd(&current_time, &delta, &end_time);
  
    struct timespec ts;
    TIMEVAL_TO_TIMESPEC(&end_time, &ts);
    // Wait for semaphore signalled or timeout.
    while (true) {
      int result = sem_timedwait(&sem_, &ts);
      if (result == 0) return true;  // Successfully got semaphore.
      if (result == -1 && errno == ETIMEDOUT) return false;  // Timeout.
      CHECK(result == -1 && errno == EINTR);  // Signal caused spurious wakeup.
    }
  }
  
  
  Semaphore* OS::CreateSemaphore(int count) {
    return new CygwinSemaphore(count);
  }
  
  
  // ----------------------------------------------------------------------------
  // Cygwin profiler support.
  //
  // On Cygwin we use the same sampler implementation as on win32.
  
  class Sampler::PlatformData : public Malloced {
   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) {
        CloseHandle(profiled_thread_);
        profiled_thread_ = NULL;
      }
    }
  
    HANDLE profiled_thread() { return profiled_thread_; }
  
   private:
    HANDLE profiled_thread_;
  };
  
  
  class SamplerThread : public Thread {
   public:
    static const int kSamplerThreadStackSize = 64 * KB;
  
    explicit SamplerThread(int interval)
        : Thread(Thread::Options("SamplerThread", kSamplerThreadStackSize)),
          interval_(interval) {}
  
    static void AddActiveSampler(Sampler* sampler) {
      ScopedLock lock(mutex_);
      SamplerRegistry::AddActiveSampler(sampler);
      if (instance_ == NULL) {
        instance_ = new SamplerThread(sampler->interval());
        instance_->Start();
      } else {
        ASSERT(instance_->interval_ == sampler->interval());
      }
    }
  
    static void RemoveActiveSampler(Sampler* sampler) {
      ScopedLock lock(mutex_);
      SamplerRegistry::RemoveActiveSampler(sampler);
      if (SamplerRegistry::GetState() == SamplerRegistry::HAS_NO_SAMPLERS) {
        RuntimeProfiler::StopRuntimeProfilerThreadBeforeShutdown(instance_);
        delete instance_;
        instance_ = NULL;
      }
    }
  
    // Implement Thread::Run().
    virtual void Run() {
      SamplerRegistry::State state;
      while ((state = SamplerRegistry::GetState()) !=
             SamplerRegistry::HAS_NO_SAMPLERS) {
        bool cpu_profiling_enabled =
            (state == SamplerRegistry::HAS_CPU_PROFILING_SAMPLERS);
        bool runtime_profiler_enabled = RuntimeProfiler::IsEnabled();
        // When CPU profiling is enabled both JavaScript and C++ code is
        // profiled. We must not suspend.
        if (!cpu_profiling_enabled) {
          if (rate_limiter_.SuspendIfNecessary()) continue;
        }
        if (cpu_profiling_enabled) {
          if (!SamplerRegistry::IterateActiveSamplers(&DoCpuProfile, this)) {
            return;
          }
        }
        if (runtime_profiler_enabled) {
          if (!SamplerRegistry::IterateActiveSamplers(&DoRuntimeProfile, NULL)) {
            return;
          }
        }
        OS::Sleep(interval_);
      }
    }
  
    static void DoCpuProfile(Sampler* sampler, void* raw_sampler_thread) {
      if (!sampler->isolate()->IsInitialized()) return;
      if (!sampler->IsProfiling()) return;
      SamplerThread* sampler_thread =
          reinterpret_cast<SamplerThread*>(raw_sampler_thread);
      sampler_thread->SampleContext(sampler);
    }
  
    static void DoRuntimeProfile(Sampler* sampler, void* ignored) {
      if (!sampler->isolate()->IsInitialized()) return;
      sampler->isolate()->runtime_profiler()->NotifyTick();
    }
  
    void SampleContext(Sampler* sampler) {
      HANDLE profiled_thread = sampler->platform_data()->profiled_thread();
      if (profiled_thread == NULL) return;
  
      // Context used for sampling the register state of the profiled thread.
      CONTEXT context;
      memset(&context, 0, sizeof(context));
  
      TickSample sample_obj;
      TickSample* sample = CpuProfiler::TickSampleEvent(sampler->isolate());
      if (sample == NULL) sample = &sample_obj;
  
      static const DWORD kSuspendFailed = static_cast<DWORD>(-1);
      if (SuspendThread(profiled_thread) == kSuspendFailed) return;
      sample->state = sampler->isolate()->current_vm_state();
  
      context.ContextFlags = CONTEXT_FULL;
      if (GetThreadContext(profiled_thread, &context) != 0) {
  #if V8_HOST_ARCH_X64
        sample->pc = reinterpret_cast<Address>(context.Rip);
        sample->sp = reinterpret_cast<Address>(context.Rsp);
        sample->fp = reinterpret_cast<Address>(context.Rbp);
  #else
        sample->pc = reinterpret_cast<Address>(context.Eip);
        sample->sp = reinterpret_cast<Address>(context.Esp);
        sample->fp = reinterpret_cast<Address>(context.Ebp);
  #endif
        sampler->SampleStack(sample);
        sampler->Tick(sample);
      }
      ResumeThread(profiled_thread);
    }
  
    const int interval_;
    RuntimeProfilerRateLimiter rate_limiter_;
  
    // Protects the process wide state below.
    static Mutex* mutex_;
    static SamplerThread* instance_;
  
   private:
    DISALLOW_COPY_AND_ASSIGN(SamplerThread);
  };
  
  
  Mutex* SamplerThread::mutex_ = OS::CreateMutex();
  SamplerThread* SamplerThread::instance_ = NULL;
  
  
  Sampler::Sampler(Isolate* isolate, int interval)
      : isolate_(isolate),
        interval_(interval),
        profiling_(false),
        active_(false),
        samples_taken_(0) {
    data_ = new PlatformData;
  }
  
  
  Sampler::~Sampler() {
    ASSERT(!IsActive());
    delete data_;
  }
  
  
  void Sampler::Start() {
    ASSERT(!IsActive());
    SetActive(true);
    SamplerThread::AddActiveSampler(this);
  }
  
  
  void Sampler::Stop() {
    ASSERT(IsActive());
    SamplerThread::RemoveActiveSampler(this);
    SetActive(false);
  }
  
  
  } }  // namespace v8::internal
  