root/src/platform-solaris.cc

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DEFINITIONS

This source file includes following definitions.
  1. signbit
  2. ceiling
  3. PostSetUp
  4. CpuFeaturesImpliedByPlatform
  5. ActivationFrameAlignment
  6. ReleaseStore
  7. LocalTimezone
  8. LocalTimeOffset
  9. UpdateAllocatedSpaceLimits
  10. IsOutsideAllocatedSpace
  11. AllocateAlignment
  12. Allocate
  13. Free
  14. Sleep
  15. Abort
  16. DebugBreak
  17. size_
  18. memory
  19. size
  20. open
  21. create
  22. LogSharedLibraryAddresses
  23. SignalCodeMovingGC
  24. StackWalkCallback
  25. StackWalk
  26. size_
  27. size_
  28. IsReserved
  29. Reset
  30. Commit
  31. Uncommit
  32. Guard
  33. ReserveRegion
  34. CommitRegion
  35. UncommitRegion
  36. ReleaseRegion
  37. PlatformData
  38. stack_size_
  39. ThreadEntry
  40. set_name
  41. Start
  42. Join
  43. CreateThreadLocalKey
  44. DeleteThreadLocalKey
  45. GetThreadLocal
  46. SetThreadLocal
  47. YieldCPU
  48. Lock
  49. Unlock
  50. TryLock
  51. CreateMutex
  52. Signal
  53. Wait
  54. Wait
  55. CreateSemaphore
  56. GetThreadID
  57. ProfilerSignalHandler
  58. PlatformData
  59. vm_tid
  60. interval_
  61. SetUp
  62. TearDown
  63. InstallSignalHandler
  64. RestoreSignalHandler
  65. AddActiveSampler
  66. RemoveActiveSampler
  67. Run
  68. DoCpuProfile
  69. DoRuntimeProfile
  70. SendProfilingSignal
  71. Sleep
  72. SetUp
  73. TearDown
  74. samples_taken_
  75. Start
  76. Stop

// 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 Solaris 10 goes here. For the POSIX comaptible
// parts the implementation is in platform-posix.cc.

#ifdef __sparc
# error "V8 does not support the SPARC CPU architecture."
#endif

#include <sys/stack.h>  // for stack alignment
#include <unistd.h>  // getpagesize(), usleep()
#include <sys/mman.h>  // mmap()
#include <ucontext.h>  // walkstack(), getcontext()
#include <dlfcn.h>     // dladdr
#include <pthread.h>
#include <sched.h>  // for sched_yield
#include <semaphore.h>
#include <time.h>
#include <sys/time.h>  // gettimeofday(), timeradd()
#include <errno.h>
#include <ieeefp.h>  // finite()
#include <signal.h>  // sigemptyset(), etc
#include <sys/regset.h>


#undef MAP_TYPE

#include "v8.h"

#include "platform-posix.h"
#include "platform.h"
#include "v8threads.h"
#include "vm-state-inl.h"


// It seems there is a bug in some Solaris distributions (experienced in
// SunOS 5.10 Generic_141445-09) which make it difficult or impossible to
// access signbit() despite the availability of other C99 math functions.
#ifndef signbit
// Test sign - usually defined in math.h
int signbit(double x) {
  // We need to take care of the special case of both positive and negative
  // versions of zero.
  if (x == 0) {
    return fpclass(x) & FP_NZERO;
  } else {
    // This won't detect negative NaN but that should be okay since we don't
    // assume that behavior.
    return x < 0;
  }
}
#endif  // signbit

namespace v8 {
namespace internal {


// 0 is never a valid thread id on Solaris since the main thread is 1 and
// subsequent have their ids incremented from there
static const pthread_t kNoThread = (pthread_t) 0;


double ceiling(double x) {
  return ceil(x);
}


static Mutex* limit_mutex = NULL;


void OS::PostSetUp() {
  POSIXPostSetUp();
}


uint64_t OS::CpuFeaturesImpliedByPlatform() {
  return 0;  // Solaris runs on a lot of things.
}


int OS::ActivationFrameAlignment() {
  // GCC generates code that requires 16 byte alignment such as movdqa.
  return Max(STACK_ALIGN, 16);
}


void OS::ReleaseStore(volatile AtomicWord* ptr, AtomicWord value) {
  __asm__ __volatile__("" : : : "memory");
  *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 Solaris.
}


double OS::LocalTimeOffset() {
  // On Solaris, 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);
  return static_cast<double>((mktime(loc) - utc) * msPerSecond);
}


// 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 static_cast<size_t>(getpagesize());
}


void* OS::Allocate(const size_t requested,
                   size_t* allocated,
                   bool is_executable) {
  const size_t msize = RoundUp(requested, getpagesize());
  int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
  void* mbase = mmap(NULL, msize, prot, MAP_PRIVATE | MAP_ANON, -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::Sleep(int milliseconds) {
  useconds_t ms = static_cast<useconds_t>(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() {
}


void OS::SignalCodeMovingGC() {
}


struct StackWalker {
  Vector<OS::StackFrame>& frames;
  int index;
};


static int StackWalkCallback(uintptr_t pc, int signo, void* data) {
  struct StackWalker* walker = static_cast<struct StackWalker*>(data);
  Dl_info info;

  int i = walker->index;

  walker->frames[i].address = reinterpret_cast<void*>(pc);

  // Make sure line termination is in place.
  walker->frames[i].text[OS::kStackWalkMaxTextLen - 1] = '\0';

  Vector<char> text = MutableCStrVector(walker->frames[i].text,
                                        OS::kStackWalkMaxTextLen);

  if (dladdr(reinterpret_cast<void*>(pc), &info) == 0) {
    OS::SNPrintF(text, "[0x%p]", pc);
  } else if ((info.dli_fname != NULL && info.dli_sname != NULL)) {
    // We have symbol info.
    OS::SNPrintF(text, "%s'%s+0x%x", info.dli_fname, info.dli_sname, pc);
  } else {
    // No local symbol info.
    OS::SNPrintF(text,
                 "%s'0x%p [0x%p]",
                 info.dli_fname,
                 pc - reinterpret_cast<uintptr_t>(info.dli_fbase),
                 pc);
  }
  walker->index++;
  return 0;
}


int OS::StackWalk(Vector<OS::StackFrame> frames) {
  ucontext_t ctx;
  struct StackWalker walker = { frames, 0 };

  if (getcontext(&ctx) < 0) return kStackWalkError;

  if (!walkcontext(&ctx, StackWalkCallback, &walker)) {
    return kStackWalkError;
  }

  return walker.index;
}


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


VirtualMemory::VirtualMemory() : address_(NULL), size_(0) { }

VirtualMemory::VirtualMemory(size_t size) {
  address_ = ReserveRegion(size);
  size_ = size;
}


VirtualMemory::VirtualMemory(size_t size, size_t alignment)
    : address_(NULL), size_(0) {
  ASSERT(IsAligned(alignment, static_cast<intptr_t>(OS::AllocateAlignment())));
  size_t request_size = RoundUp(size + alignment,
                                static_cast<intptr_t>(OS::AllocateAlignment()));
  void* reservation = mmap(OS::GetRandomMmapAddr(),
                           request_size,
                           PROT_NONE,
                           MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE,
                           kMmapFd,
                           kMmapFdOffset);
  if (reservation == MAP_FAILED) return;

  Address base = static_cast<Address>(reservation);
  Address aligned_base = RoundUp(base, alignment);
  ASSERT_LE(base, aligned_base);

  // Unmap extra memory reserved before and after the desired block.
  if (aligned_base != base) {
    size_t prefix_size = static_cast<size_t>(aligned_base - base);
    OS::Free(base, prefix_size);
    request_size -= prefix_size;
  }

  size_t aligned_size = RoundUp(size, OS::AllocateAlignment());
  ASSERT_LE(aligned_size, request_size);

  if (aligned_size != request_size) {
    size_t suffix_size = request_size - aligned_size;
    OS::Free(aligned_base + aligned_size, suffix_size);
    request_size -= suffix_size;
  }

  ASSERT(aligned_size == request_size);

  address_ = static_cast<void*>(aligned_base);
  size_ = aligned_size;
}


VirtualMemory::~VirtualMemory() {
  if (IsReserved()) {
    bool result = ReleaseRegion(address(), size());
    ASSERT(result);
    USE(result);
  }
}


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


void VirtualMemory::Reset() {
  address_ = NULL;
  size_ = 0;
}


bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) {
  return CommitRegion(address, size, is_executable);
}


bool VirtualMemory::Uncommit(void* address, size_t size) {
  return UncommitRegion(address, size);
}


bool VirtualMemory::Guard(void* address) {
  OS::Guard(address, OS::CommitPageSize());
  return true;
}


void* VirtualMemory::ReserveRegion(size_t size) {
  void* result = mmap(OS::GetRandomMmapAddr(),
                      size,
                      PROT_NONE,
                      MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE,
                      kMmapFd,
                      kMmapFdOffset);

  if (result == MAP_FAILED) return NULL;

  return result;
}


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

  UpdateAllocatedSpaceLimits(base, size);
  return true;
}


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


bool VirtualMemory::ReleaseRegion(void* base, size_t size) {
  return munmap(base, size) == 0;
}


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;
  if (stack_size_ > 0) {
    pthread_attr_init(&attr);
    pthread_attr_setstacksize(&attr, static_cast<size_t>(stack_size_));
  }
  pthread_create(&data_->thread_, NULL, ThreadEntry, this);
  ASSERT(data_->thread_ != kNoThread);
}


void Thread::Join() {
  pthread_join(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 SolarisMutex : public Mutex {
 public:
  SolarisMutex() {
    pthread_mutexattr_t attr;
    pthread_mutexattr_init(&attr);
    pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
    pthread_mutex_init(&mutex_, &attr);
  }

  ~SolarisMutex() { pthread_mutex_destroy(&mutex_); }

  int Lock() { return pthread_mutex_lock(&mutex_); }

  int Unlock() { return pthread_mutex_unlock(&mutex_); }

  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_;
};


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


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

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


void SolarisSemaphore::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


#ifndef timeradd
#define timeradd(a, b, result) \
  do { \
    (result)->tv_sec = (a)->tv_sec + (b)->tv_sec; \
    (result)->tv_usec = (a)->tv_usec + (b)->tv_usec; \
    if ((result)->tv_usec >= 1000000) { \
      ++(result)->tv_sec; \
      (result)->tv_usec -= 1000000; \
    } \
  } while (0)
#endif


bool SolarisSemaphore::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 SolarisSemaphore(count);
}


static pthread_t GetThreadID() {
  return pthread_self();
}

static void ProfilerSignalHandler(int signal, siginfo_t* info, void* context) {
  USE(info);
  if (signal != SIGPROF) return;
  Isolate* isolate = Isolate::UncheckedCurrent();
  if (isolate == NULL || !isolate->IsInitialized() || !isolate->IsInUse()) {
    // We require a fully initialized and entered isolate.
    return;
  }
  if (v8::Locker::IsActive() &&
      !isolate->thread_manager()->IsLockedByCurrentThread()) {
    return;
  }

  Sampler* sampler = isolate->logger()->sampler();
  if (sampler == NULL || !sampler->IsActive()) return;

  TickSample sample_obj;
  TickSample* sample = CpuProfiler::TickSampleEvent(isolate);
  if (sample == NULL) sample = &sample_obj;

  // Extracting the sample from the context is extremely machine dependent.
  ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(context);
  mcontext_t& mcontext = ucontext->uc_mcontext;
  sample->state = isolate->current_vm_state();

  sample->pc = reinterpret_cast<Address>(mcontext.gregs[REG_PC]);
  sample->sp = reinterpret_cast<Address>(mcontext.gregs[REG_SP]);
  sample->fp = reinterpret_cast<Address>(mcontext.gregs[REG_FP]);

  sampler->SampleStack(sample);
  sampler->Tick(sample);
}

class Sampler::PlatformData : public Malloced {
 public:
  PlatformData() : vm_tid_(GetThreadID()) {}

  pthread_t vm_tid() const { return vm_tid_; }

 private:
  pthread_t vm_tid_;
};


class SignalSender : public Thread {
 public:
  enum SleepInterval {
    HALF_INTERVAL,
    FULL_INTERVAL
  };

  static const int kSignalSenderStackSize = 64 * KB;

  explicit SignalSender(int interval)
      : Thread(Thread::Options("SignalSender", kSignalSenderStackSize)),
        interval_(interval) {}

  static void SetUp() { if (!mutex_) mutex_ = OS::CreateMutex(); }
  static void TearDown() { delete mutex_; }

  static void InstallSignalHandler() {
    struct sigaction sa;
    sa.sa_sigaction = ProfilerSignalHandler;
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = SA_RESTART | SA_SIGINFO;
    signal_handler_installed_ =
        (sigaction(SIGPROF, &sa, &old_signal_handler_) == 0);
  }

  static void RestoreSignalHandler() {
    if (signal_handler_installed_) {
      sigaction(SIGPROF, &old_signal_handler_, 0);
      signal_handler_installed_ = false;
    }
  }

  static void AddActiveSampler(Sampler* sampler) {
    ScopedLock lock(mutex_);
    SamplerRegistry::AddActiveSampler(sampler);
    if (instance_ == NULL) {
      // Start a thread that will send SIGPROF signal to VM threads,
      // when CPU profiling will be enabled.
      instance_ = new SignalSender(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;
      RestoreSignalHandler();
    }
  }

  // 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();
      if (cpu_profiling_enabled && !signal_handler_installed_) {
        InstallSignalHandler();
      } else if (!cpu_profiling_enabled && signal_handler_installed_) {
        RestoreSignalHandler();
      }

      // 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 && runtime_profiler_enabled) {
        if (!SamplerRegistry::IterateActiveSamplers(&DoCpuProfile, this)) {
          return;
        }
        Sleep(HALF_INTERVAL);
        if (!SamplerRegistry::IterateActiveSamplers(&DoRuntimeProfile, NULL)) {
          return;
        }
        Sleep(HALF_INTERVAL);
      } else {
        if (cpu_profiling_enabled) {
          if (!SamplerRegistry::IterateActiveSamplers(&DoCpuProfile,
                                                      this)) {
            return;
          }
        }
        if (runtime_profiler_enabled) {
          if (!SamplerRegistry::IterateActiveSamplers(&DoRuntimeProfile,
                                                      NULL)) {
            return;
          }
        }
        Sleep(FULL_INTERVAL);
      }
    }
  }

  static void DoCpuProfile(Sampler* sampler, void* raw_sender) {
    if (!sampler->IsProfiling()) return;
    SignalSender* sender = reinterpret_cast<SignalSender*>(raw_sender);
    sender->SendProfilingSignal(sampler->platform_data()->vm_tid());
  }

  static void DoRuntimeProfile(Sampler* sampler, void* ignored) {
    if (!sampler->isolate()->IsInitialized()) return;
    sampler->isolate()->runtime_profiler()->NotifyTick();
  }

  void SendProfilingSignal(pthread_t tid) {
    if (!signal_handler_installed_) return;
    pthread_kill(tid, SIGPROF);
  }

  void Sleep(SleepInterval full_or_half) {
    // Convert ms to us and subtract 100 us to compensate delays
    // occuring during signal delivery.
    useconds_t interval = interval_ * 1000 - 100;
    if (full_or_half == HALF_INTERVAL) interval /= 2;
    int result = usleep(interval);
#ifdef DEBUG
    if (result != 0 && errno != EINTR) {
      fprintf(stderr,
              "SignalSender usleep error; interval = %u, errno = %d\n",
              interval,
              errno);
      ASSERT(result == 0 || errno == EINTR);
    }
#endif
    USE(result);
  }

  const int interval_;
  RuntimeProfilerRateLimiter rate_limiter_;

  // Protects the process wide state below.
  static Mutex* mutex_;
  static SignalSender* instance_;
  static bool signal_handler_installed_;
  static struct sigaction old_signal_handler_;

 private:
  DISALLOW_COPY_AND_ASSIGN(SignalSender);
};

Mutex* SignalSender::mutex_ = NULL;
SignalSender* SignalSender::instance_ = NULL;
struct sigaction SignalSender::old_signal_handler_;
bool SignalSender::signal_handler_installed_ = false;


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 will 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();
  SignalSender::SetUp();
}


void OS::TearDown() {
  SignalSender::TearDown();
  delete limit_mutex;
}


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);
  SignalSender::AddActiveSampler(this);
}


void Sampler::Stop() {
  ASSERT(IsActive());
  SignalSender::RemoveActiveSampler(this);
  SetActive(false);
}

} }  // namespace v8::internal

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