garbage_collector.cc revision 3f9667022788ba1effcd1e47fc9e3decc4db569d 
1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#define ATRACE_TAG ATRACE_TAG_DALVIK
18
19#include <stdio.h>
20#include <cutils/trace.h>
21
22#include "garbage_collector.h"
23
24#include "base/logging.h"
25#include "base/mutex-inl.h"
26#include "gc/accounting/heap_bitmap.h"
27#include "gc/space/large_object_space.h"
28#include "gc/space/space-inl.h"
29#include "thread.h"
30#include "thread_list.h"
31
32namespace art {
33namespace gc {
34namespace collector {
35
36GarbageCollector::GarbageCollector(Heap* heap, const std::string& name)
37    : heap_(heap),
38      name_(name),
39      verbose_(VLOG_IS_ON(heap)),
40      duration_ns_(0),
41      timings_(name_.c_str(), true, verbose_),
42      cumulative_timings_(name) {
43  ResetCumulativeStatistics();
44}
45
46bool GarbageCollector::HandleDirtyObjectsPhase() {
47  DCHECK(IsConcurrent());
48  return true;
49}
50
51void GarbageCollector::RegisterPause(uint64_t nano_length) {
52  pause_times_.push_back(nano_length);
53}
54
55void GarbageCollector::ResetCumulativeStatistics() {
56  cumulative_timings_.Reset();
57  total_time_ns_ = 0;
58  total_paused_time_ns_ = 0;
59  total_freed_objects_ = 0;
60  total_freed_bytes_ = 0;
61}
62
63void GarbageCollector::Run() {
64  ThreadList* thread_list = Runtime::Current()->GetThreadList();
65  uint64_t start_time = NanoTime();
66  pause_times_.clear();
67  duration_ns_ = 0;
68
69  InitializePhase();
70
71  if (!IsConcurrent()) {
72    // Pause is the entire length of the GC.
73    uint64_t pause_start = NanoTime();
74    ATRACE_BEGIN("Application threads suspended");
75    thread_list->SuspendAll();
76    MarkingPhase();
77    ReclaimPhase();
78    thread_list->ResumeAll();
79    ATRACE_END();
80    uint64_t pause_end = NanoTime();
81    pause_times_.push_back(pause_end - pause_start);
82  } else {
83    Thread* self = Thread::Current();
84    {
85      ReaderMutexLock mu(self, *Locks::mutator_lock_);
86      MarkingPhase();
87    }
88    bool done = false;
89    while (!done) {
90      uint64_t pause_start = NanoTime();
91      ATRACE_BEGIN("Suspending mutator threads");
92      thread_list->SuspendAll();
93      ATRACE_END();
94      ATRACE_BEGIN("All mutator threads suspended");
95      done = HandleDirtyObjectsPhase();
96      ATRACE_END();
97      uint64_t pause_end = NanoTime();
98      ATRACE_BEGIN("Resuming mutator threads");
99      thread_list->ResumeAll();
100      ATRACE_END();
101      pause_times_.push_back(pause_end - pause_start);
102    }
103    {
104      ReaderMutexLock mu(self, *Locks::mutator_lock_);
105      ReclaimPhase();
106    }
107  }
108
109  uint64_t end_time = NanoTime();
110  duration_ns_ = end_time - start_time;
111
112  FinishPhase();
113}
114
115void GarbageCollector::SwapBitmaps() {
116  // Swap the live and mark bitmaps for each alloc space. This is needed since sweep re-swaps
117  // these bitmaps. The bitmap swapping is an optimization so that we do not need to clear the live
118  // bits of dead objects in the live bitmap.
119  const GcType gc_type = GetGcType();
120  for (const auto& space : GetHeap()->GetContinuousSpaces()) {
121    // We never allocate into zygote spaces.
122    if (space->GetGcRetentionPolicy() == space::kGcRetentionPolicyAlwaysCollect ||
123        (gc_type == kGcTypeFull &&
124         space->GetGcRetentionPolicy() == space::kGcRetentionPolicyFullCollect)) {
125      accounting::SpaceBitmap* live_bitmap = space->GetLiveBitmap();
126      accounting::SpaceBitmap* mark_bitmap = space->GetMarkBitmap();
127      if (live_bitmap != mark_bitmap) {
128        heap_->GetLiveBitmap()->ReplaceBitmap(live_bitmap, mark_bitmap);
129        heap_->GetMarkBitmap()->ReplaceBitmap(mark_bitmap, live_bitmap);
130        space->AsDlMallocSpace()->SwapBitmaps();
131      }
132    }
133  }
134  for (const auto& disc_space : GetHeap()->GetDiscontinuousSpaces()) {
135    space::LargeObjectSpace* space = down_cast<space::LargeObjectSpace*>(disc_space);
136    accounting::SpaceSetMap* live_set = space->GetLiveObjects();
137    accounting::SpaceSetMap* mark_set = space->GetMarkObjects();
138    heap_->GetLiveBitmap()->ReplaceObjectSet(live_set, mark_set);
139    heap_->GetMarkBitmap()->ReplaceObjectSet(mark_set, live_set);
140    down_cast<space::LargeObjectSpace*>(space)->SwapBitmaps();
141  }
142}
143
144}  // namespace collector
145}  // namespace gc
146}  // namespace art
147