Parallel and concurrent sweeping.

src/sweeper-thread.cc

+// 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.
+
+#include "sweeper-thread.h"
+
+#include "v8.h"
+
+#include "isolate.h"
+#include "v8threads.h"
+
+namespace v8 {
+namespace internal {
+
+SweeperThread::SweeperThread(Isolate* isolate)
+     : Thread("SweeperThread"),
+       isolate_(isolate),
+       heap_(isolate->heap()),
+       collector_(heap_->mark_compact_collector()),
+       start_sweeping_semaphore_(OS::CreateSemaphore(0)),
+       end_sweeping_semaphore_(OS::CreateSemaphore(0)),
+       stop_semaphore_(OS::CreateSemaphore(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)),
+       sweeper_type_(CONSERVATIVE) {
+  NoBarrier_Store(&stop_thread_, static_cast<AtomicWord>(false));
+}
+
+
+bool SweeperThread::sweeping_pending_ = false;
+
+
+void SweeperThread::Run() {
+  Isolate::SetIsolateThreadLocals(isolate_, NULL);
+  while (true) {
+    start_sweeping_semaphore_->Wait();
+
+    if (Acquire_Load(&stop_thread_)) {
+      stop_semaphore_->Signal();
+      return;
+    }
+
+    collector_->SweepInParallel(heap_->old_data_space(),
+                                sweeper_type_,
+                                &private_free_list_old_data_space_,
+                                &free_list_old_data_space_);
+    collector_->SweepInParallel(heap_->old_pointer_space(),
+                                sweeper_type_,
+                                &private_free_list_old_pointer_space_,
+                                &free_list_old_pointer_space_);
+    end_sweeping_semaphore_->Signal();
+  }
+}
+
+intptr_t SweeperThread::StealMemory(PagedSpace* space) {
+  intptr_t free_bytes = 0;
+  if (space->identity() == OLD_POINTER_SPACE) {
+    free_bytes = space->free_list()->Concatenate(&free_list_old_pointer_space_);
+    space->AddToAccountingStats(free_bytes);
+  } else if (space->identity() == OLD_DATA_SPACE) {
+    free_bytes = space->free_list()->Concatenate(&free_list_old_data_space_);
+    space->AddToAccountingStats(free_bytes);
+  }
+  return free_bytes;
+}
+
+void SweeperThread::Stop() {
+  Release_Store(&stop_thread_, static_cast<AtomicWord>(true));
+  start_sweeping_semaphore_->Signal();
+  stop_semaphore_->Wait();
+}
+
+
+void SweeperThread::StartSweeping(SweeperType sweeper_type) {
+  sweeper_type_ = sweeper_type;
+  start_sweeping_semaphore_->Signal();
+}
+
+
+void SweeperThread::WaitForSweeperThread() {
+  end_sweeping_semaphore_->Wait();
+}
+} }  // namespace v8::internal