Cygwin support

src/platform-cygwin.cc

+// Copyright 2006-2011 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 "top.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);
+}
+
+
+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));
+}
+
+
+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, ie, 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) {
+  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(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);
+}
+
+
+#ifdef ENABLE_HEAP_PROTECTION
+
+void OS::Protect(void* address, size_t size) {
+  // TODO(1240712): mprotect has a return value which is ignored here.
+  mprotect(address, size, PROT_READ);
+}
+
+
+void OS::Unprotect(void* address, size_t size, bool is_executable) {
+  // TODO(1240712): mprotect has a return value which is ignored here.
+  int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
+  mprotect(address, size, prot);
+}
+
+#endif
+
+
+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, "w+");
+  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() {
+#ifdef ENABLE_LOGGING_AND_PROFILING
+  // 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));
+
+  // 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(SharedLibraryEvent(lib_name, start, end));
+    } else {
+      // Entry not describing executable data. Skip to end of line to setup
+      // reading the next entry.
+      do {
+        c = getc(fp);
+      } while ((c != EOF) && (c != '\n'));
+      if (c == EOF) break;
+    }
+  }
+  free(lib_name);
+  fclose(fp);
+#endif
+}
+
+
+void OS::SignalCodeMovingGC() {
+  // Nothing to do on Cygwin.
+}
+
+
+int OS::StackWalk(Vector<OS::StackFrame> frames) {
+  // Not supported on Cygwin.
+  return 0;
+}
+
+
+// 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 is_executable) {
+  int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
+
+  if (mprotect(address, size, prot) != 0) {
+    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) {
+  set_name("v8:<unknown>");
+}
+
+
+Thread::Thread(const char* name) : ThreadHandle(ThreadHandle::INVALID) {
+  set_name(name);
+}
+
+
+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::set_name(const char* name) {
+  strncpy(name_, name, sizeof(name_));
+  name_[sizeof(name_) - 1] = '\0';
+}
+
+
+void Thread::Start() {
+  pthread_create(&thread_handle_data()->thread_, NULL, ThreadEntry, this);
+  ASSERT(IsValid());
+}
+
+
+void Thread::Join() {
+  pthread_join(thread_handle_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);
+}
+
+
+#ifdef ENABLE_LOGGING_AND_PROFILING
+
+// ----------------------------------------------------------------------------
+// Cygwin profiler support.
+//
+// On Cygwin we use the same sampler implementation as on win32.
+
+class Sampler::PlatformData : public Malloced {
+ public:
+  explicit PlatformData(Sampler* sampler) {
+    sampler_ = sampler;
+    sampler_thread_ = INVALID_HANDLE_VALUE;
+    profiled_thread_ = INVALID_HANDLE_VALUE;
+  }
+
+  Sampler* sampler_;
+  HANDLE sampler_thread_;
+  HANDLE profiled_thread_;
+  RuntimeProfilerRateLimiter rate_limiter_;
+
+  // Sampler thread handler.
+  void Runner() {
+    while (sampler_->IsActive()) {
+      if (rate_limiter_.SuspendIfNecessary()) continue;
+      Sample();
+      Sleep(sampler_->interval_);
+    }
+  }
+
+  void Sample() {
+    if (sampler_->IsProfiling()) {
+      // 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();
+      if (sample == NULL) sample = &sample_obj;
+
+      static const DWORD kSuspendFailed = static_cast<DWORD>(-1);
+      if (SuspendThread(profiled_thread_) == kSuspendFailed) return;
+      sample->state = Top::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_);
+    }
+    if (RuntimeProfiler::IsEnabled()) RuntimeProfiler::NotifyTick();
+  }
+};
+
+
+// Entry point for sampler thread.
+static DWORD __stdcall SamplerEntry(void* arg) {
+  Sampler::PlatformData* data =
+      reinterpret_cast<Sampler::PlatformData*>(arg);
+  data->Runner();
+  return 0;
+}
+
+
+// Initialize a profile sampler.
+Sampler::Sampler(int interval)
+    : interval_(interval),
+      profiling_(false),
+      active_(false),
+      samples_taken_(0) {
+  data_ = new PlatformData(this);
+}
+
+
+Sampler::~Sampler() {
+  delete data_;
+}
+
+
+// Start profiling.
+void Sampler::Start() {
+  // Do not start multiple threads for the same sampler.
+  ASSERT(!IsActive());
+
+  // 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.
+  data_->profiled_thread_ = OpenThread(THREAD_GET_CONTEXT |
+                                       THREAD_SUSPEND_RESUME |
+                                       THREAD_QUERY_INFORMATION,
+                                       false,
+                                       GetCurrentThreadId());
+  BOOL ok = data_->profiled_thread_ != NULL;
+  if (!ok) return;
+
+  // Start sampler thread.
+  DWORD tid;
+  SetActive(true);
+  data_->sampler_thread_ = CreateThread(NULL, 0, SamplerEntry, data_, 0, &tid);
+  // Set thread to high priority to increase sampling accuracy.
+  SetThreadPriority(data_->sampler_thread_, THREAD_PRIORITY_TIME_CRITICAL);
+}
+
+
+// Stop profiling.
+void Sampler::Stop() {
+  // Seting active to false triggers termination of the sampler
+  // thread.
+  SetActive(false);
+
+  // Wait for sampler thread to terminate.
+  Top::WakeUpRuntimeProfilerThreadBeforeShutdown();
+  WaitForSingleObject(data_->sampler_thread_, INFINITE);
+
+  // Release the thread handles
+  CloseHandle(data_->sampler_thread_);
+  CloseHandle(data_->profiled_thread_);
+}
+
+
+#endif  // ENABLE_LOGGING_AND_PROFILING
+
+} }  // namespace v8::internal
+