src/sweeper-thread.cc

// Copyright 2012 the V8 project authors. All rights reserved.
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#include "sweeper-thread.h"

#include "v8.h"

#include "isolate.h"
#include "v8threads.h"

namespace v8 {
namespace internal {

static const int kSweeperThreadStackSize = 64 * KB;

SweeperThread::SweeperThread(Isolate* isolate)
     : Thread(Thread::Options("v8:SweeperThread", kSweeperThreadStackSize)),
       isolate_(isolate),
       heap_(isolate->heap()),
       collector_(heap_->mark_compact_collector()),
       start_sweeping_semaphore_(0),
       end_sweeping_semaphore_(0),
       stop_semaphore_(0),
       free_list_old_data_space_(heap_->paged_space(OLD_DATA_SPACE)),
       free_list_old_pointer_space_(heap_->paged_space(OLD_POINTER_SPACE)),
       private_free_list_old_data_space_(heap_->paged_space(OLD_DATA_SPACE)),
       private_free_list_old_pointer_space_(
           heap_->paged_space(OLD_POINTER_SPACE)) {
  NoBarrier_Store(&stop_thread_, static_cast<AtomicWord>(false));
}


void SweeperThread::Run() {
  Isolate::SetIsolateThreadLocals(isolate_, NULL);
  DisallowHeapAllocation no_allocation;
  DisallowHandleAllocation no_handles;
  DisallowHandleDereference no_deref;

  while (true) {
    start_sweeping_semaphore_.Wait();

    if (Acquire_Load(&stop_thread_)) {
      stop_semaphore_.Signal();
      return;
    }

    collector_->SweepInParallel(heap_->old_data_space(),
                                &private_free_list_old_data_space_,
                                &free_list_old_data_space_);
    collector_->SweepInParallel(heap_->old_pointer_space(),
                                &private_free_list_old_pointer_space_,
                                &free_list_old_pointer_space_);
    end_sweeping_semaphore_.Signal();
  }
}


intptr_t SweeperThread::StealMemory(PagedSpace* space) {
  if (space->identity() == OLD_POINTER_SPACE) {
    return space->free_list()->Concatenate(&free_list_old_pointer_space_);
  } else if (space->identity() == OLD_DATA_SPACE) {
    return space->free_list()->Concatenate(&free_list_old_data_space_);
  }
  return 0;
}


void SweeperThread::Stop() {
  Release_Store(&stop_thread_, static_cast<AtomicWord>(true));
  start_sweeping_semaphore_.Signal();
  stop_semaphore_.Wait();
  Join();
}


void SweeperThread::StartSweeping() {
  start_sweeping_semaphore_.Signal();
}


void SweeperThread::WaitForSweeperThread() {
  end_sweeping_semaphore_.Wait();
}
} }  // namespace v8::internal