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      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 #ifndef ART_RUNTIME_GC_COLLECTOR_GARBAGE_COLLECTOR_H_
     18 #define ART_RUNTIME_GC_COLLECTOR_GARBAGE_COLLECTOR_H_
     19 
     20 #include "base/histogram.h"
     21 #include "base/mutex.h"
     22 #include "base/timing_logger.h"
     23 #include "gc/collector_type.h"
     24 #include "gc/gc_cause.h"
     25 #include "gc_root.h"
     26 #include "gc_type.h"
     27 #include <stdint.h>
     28 #include <vector>
     29 
     30 namespace art {
     31 namespace gc {
     32 
     33 class Heap;
     34 
     35 namespace collector {
     36 
     37 struct ObjectBytePair {
     38   ObjectBytePair(uint64_t num_objects = 0, int64_t num_bytes = 0)
     39       : objects(num_objects), bytes(num_bytes) {}
     40   void Add(const ObjectBytePair& other) {
     41     objects += other.objects;
     42     bytes += other.bytes;
     43   }
     44   // Number of objects which were freed.
     45   uint64_t objects;
     46   // Freed bytes are signed since the GC can free negative bytes if it promotes objects to a space
     47   // which has a larger allocation size.
     48   int64_t bytes;
     49 };
     50 
     51 // A information related single garbage collector iteration. Since we only ever have one GC running
     52 // at any given time, we can have a single iteration info.
     53 class Iteration {
     54  public:
     55   Iteration();
     56   // Returns how long the mutators were paused in nanoseconds.
     57   const std::vector<uint64_t>& GetPauseTimes() const {
     58     return pause_times_;
     59   }
     60   TimingLogger* GetTimings() {
     61     return &timings_;
     62   }
     63   // Returns how long the GC took to complete in nanoseconds.
     64   uint64_t GetDurationNs() const {
     65     return duration_ns_;
     66   }
     67   int64_t GetFreedBytes() const {
     68     return freed_.bytes;
     69   }
     70   int64_t GetFreedLargeObjectBytes() const {
     71     return freed_los_.bytes;
     72   }
     73   uint64_t GetFreedObjects() const {
     74     return freed_.objects;
     75   }
     76   uint64_t GetFreedLargeObjects() const {
     77     return freed_los_.objects;
     78   }
     79   uint64_t GetFreedRevokeBytes() const {
     80     return freed_bytes_revoke_;
     81   }
     82   void SetFreedRevoke(uint64_t freed) {
     83     freed_bytes_revoke_ = freed;
     84   }
     85   void Reset(GcCause gc_cause, bool clear_soft_references);
     86   // Returns the estimated throughput of the iteration.
     87   uint64_t GetEstimatedThroughput() const;
     88   bool GetClearSoftReferences() const {
     89     return clear_soft_references_;
     90   }
     91   void SetClearSoftReferences(bool clear_soft_references) {
     92     clear_soft_references_ = clear_soft_references;
     93   }
     94   GcCause GetGcCause() const {
     95     return gc_cause_;
     96   }
     97 
     98  private:
     99   void SetDurationNs(uint64_t duration) {
    100     duration_ns_ = duration;
    101   }
    102 
    103   GcCause gc_cause_;
    104   bool clear_soft_references_;
    105   uint64_t duration_ns_;
    106   TimingLogger timings_;
    107   ObjectBytePair freed_;
    108   ObjectBytePair freed_los_;
    109   uint64_t freed_bytes_revoke_;  // see Heap::num_bytes_freed_revoke_.
    110   std::vector<uint64_t> pause_times_;
    111 
    112   friend class GarbageCollector;
    113   DISALLOW_COPY_AND_ASSIGN(Iteration);
    114 };
    115 
    116 class GarbageCollector : public RootVisitor {
    117  public:
    118   class SCOPED_LOCKABLE ScopedPause {
    119    public:
    120     explicit ScopedPause(GarbageCollector* collector) EXCLUSIVE_LOCK_FUNCTION(Locks::mutator_lock_);
    121     ~ScopedPause() UNLOCK_FUNCTION();
    122 
    123    private:
    124     const uint64_t start_time_;
    125     GarbageCollector* const collector_;
    126   };
    127 
    128   GarbageCollector(Heap* heap, const std::string& name);
    129   virtual ~GarbageCollector() { }
    130   const char* GetName() const {
    131     return name_.c_str();
    132   }
    133   virtual GcType GetGcType() const = 0;
    134   virtual CollectorType GetCollectorType() const = 0;
    135   // Run the garbage collector.
    136   void Run(GcCause gc_cause, bool clear_soft_references);
    137   Heap* GetHeap() const {
    138     return heap_;
    139   }
    140   void RegisterPause(uint64_t nano_length);
    141   const CumulativeLogger& GetCumulativeTimings() const {
    142     return cumulative_timings_;
    143   }
    144   void ResetCumulativeStatistics();
    145   // Swap the live and mark bitmaps of spaces that are active for the collector. For partial GC,
    146   // this is the allocation space, for full GC then we swap the zygote bitmaps too.
    147   void SwapBitmaps() EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
    148   uint64_t GetTotalPausedTimeNs() LOCKS_EXCLUDED(pause_histogram_lock_);
    149   int64_t GetTotalFreedBytes() const {
    150     return total_freed_bytes_;
    151   }
    152   uint64_t GetTotalFreedObjects() const {
    153     return total_freed_objects_;
    154   }
    155   // Reset the cumulative timings and pause histogram.
    156   void ResetMeasurements();
    157   // Returns the estimated throughput in bytes / second.
    158   uint64_t GetEstimatedMeanThroughput() const;
    159   // Returns how many GC iterations have been run.
    160   size_t NumberOfIterations() const {
    161     return GetCumulativeTimings().GetIterations();
    162   }
    163   // Returns the current GC iteration and assocated info.
    164   Iteration* GetCurrentIteration();
    165   const Iteration* GetCurrentIteration() const;
    166   TimingLogger* GetTimings() {
    167     return &GetCurrentIteration()->timings_;
    168   }
    169   // Record a free of normal objects.
    170   void RecordFree(const ObjectBytePair& freed);
    171   // Record a free of large objects.
    172   void RecordFreeLOS(const ObjectBytePair& freed);
    173   void DumpPerformanceInfo(std::ostream& os) LOCKS_EXCLUDED(pause_histogram_lock_);
    174 
    175  protected:
    176   // Run all of the GC phases.
    177   virtual void RunPhases() = 0;
    178   // Revoke all the thread-local buffers.
    179   virtual void RevokeAllThreadLocalBuffers() = 0;
    180 
    181   static constexpr size_t kPauseBucketSize = 500;
    182   static constexpr size_t kPauseBucketCount = 32;
    183 
    184   Heap* const heap_;
    185   std::string name_;
    186   // Cumulative statistics.
    187   Histogram<uint64_t> pause_histogram_ GUARDED_BY(pause_histogram_lock_);
    188   uint64_t total_time_ns_;
    189   uint64_t total_freed_objects_;
    190   int64_t total_freed_bytes_;
    191   CumulativeLogger cumulative_timings_;
    192   mutable Mutex pause_histogram_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
    193 
    194  private:
    195   DISALLOW_IMPLICIT_CONSTRUCTORS(GarbageCollector);
    196 };
    197 
    198 }  // namespace collector
    199 }  // namespace gc
    200 }  // namespace art
    201 
    202 #endif  // ART_RUNTIME_GC_COLLECTOR_GARBAGE_COLLECTOR_H_
    203