sanitizer_quarantine.h revision e174cd1ee373c3b77f3ce8e7fc62f70d0668d03d 
1//===-- sanitizer_quarantine.h ----------------------------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// Memory quarantine for AddressSanitizer and potentially other tools.
11// Quarantine caches some specified amount of memory in per-thread caches,
12// then evicts to global FIFO queue. When the queue reaches specified threshold,
13// oldest memory is recycled.
14//
15//===----------------------------------------------------------------------===//
16
17#ifndef SANITIZER_QUARANTINE_H
18#define SANITIZER_QUARANTINE_H
19
20#include "sanitizer_internal_defs.h"
21#include "sanitizer_mutex.h"
22#include "sanitizer_list.h"
23
24namespace __sanitizer {
25
26template<typename Node> class QuarantineCache;
27
28struct QuarantineBatch {
29  static const uptr kSize = 1024;
30  QuarantineBatch *next;
31  uptr size;
32  uptr count;
33  void *batch[kSize];
34};
35
36// The callback interface is:
37// void Callback::Recycle(Node *ptr);
38// void *cb.Allocate(uptr size);
39// void cb.Deallocate(void *ptr);
40template<typename Callback, typename Node>
41class Quarantine {
42 public:
43  typedef QuarantineCache<Callback> Cache;
44
45  explicit Quarantine(LinkerInitialized)
46      : cache_(LINKER_INITIALIZED) {
47  }
48
49  void Init(uptr size, uptr cache_size) {
50    max_size_ = size;
51    min_size_ = size / 10 * 9;  // 90% of max size.
52    max_cache_size_ = cache_size;
53  }
54
55  void Put(Cache *c, Callback cb, Node *ptr, uptr size) {
56    c->Enqueue(cb, ptr, size);
57    if (c->Size() > max_cache_size_)
58      Drain(c, cb);
59  }
60
61  void NOINLINE Drain(Cache *c, Callback cb) {
62    {
63      SpinMutexLock l(&cache_mutex_);
64      cache_.Transfer(c);
65    }
66    if (cache_.Size() > max_size_ && recycle_mutex_.TryLock())
67      Recycle(cb);
68  }
69
70 private:
71  // Read-only data.
72  char pad0_[kCacheLineSize];
73  uptr max_size_;
74  uptr min_size_;
75  uptr max_cache_size_;
76  char pad1_[kCacheLineSize];
77  SpinMutex cache_mutex_;
78  SpinMutex recycle_mutex_;
79  Cache cache_;
80  char pad2_[kCacheLineSize];
81
82  void NOINLINE Recycle(Callback cb) {
83    Cache tmp;
84    {
85      SpinMutexLock l(&cache_mutex_);
86      while (cache_.Size() > min_size_) {
87        QuarantineBatch *b = cache_.DequeueBatch();
88        tmp.EnqueueBatch(b);
89      }
90    }
91    recycle_mutex_.Unlock();
92    DoRecycle(&tmp, cb);
93  }
94
95  void NOINLINE DoRecycle(Cache *c, Callback cb) {
96    while (QuarantineBatch *b = c->DequeueBatch()) {
97      const uptr kPrefetch = 16;
98      for (uptr i = 0; i < kPrefetch; i++)
99        PREFETCH(b->batch[i]);
100      for (uptr i = 0; i < b->count; i++) {
101        PREFETCH(b->batch[i + kPrefetch]);
102        cb.Recycle((Node*)b->batch[i]);
103      }
104      cb.Deallocate(b);
105    }
106  }
107};
108
109// Per-thread cache of memory blocks.
110template<typename Callback>
111class QuarantineCache {
112 public:
113  explicit QuarantineCache(LinkerInitialized) {
114  }
115
116  QuarantineCache()
117      : size_() {
118    list_.clear();
119  }
120
121  uptr Size() const {
122    return atomic_load(&size_, memory_order_relaxed);
123  }
124
125  void Enqueue(Callback cb, void *ptr, uptr size) {
126    if (list_.empty() || list_.back()->count == QuarantineBatch::kSize)
127      AllocBatch(cb);
128    QuarantineBatch *b = list_.back();
129    b->batch[b->count++] = ptr;
130    b->size += size;
131    SizeAdd(size);
132  }
133
134  void Transfer(QuarantineCache *c) {
135    list_.append_back(&c->list_);
136    SizeAdd(c->Size());
137    atomic_store(&c->size_, 0, memory_order_relaxed);
138  }
139
140  void EnqueueBatch(QuarantineBatch *b) {
141    list_.push_back(b);
142    SizeAdd(b->size);
143  }
144
145  QuarantineBatch *DequeueBatch() {
146    if (list_.empty())
147      return 0;
148    QuarantineBatch *b = list_.front();
149    list_.pop_front();
150    // FIXME: should probably add SizeSub method?
151    // See https://code.google.com/p/thread-sanitizer/issues/detail?id=20
152    SizeAdd(0 - b->size);
153    return b;
154  }
155
156 private:
157  IntrusiveList<QuarantineBatch> list_;
158  atomic_uintptr_t size_;
159
160  void SizeAdd(uptr add) {
161    atomic_store(&size_, Size() + add, memory_order_relaxed);
162  }
163
164  NOINLINE QuarantineBatch* AllocBatch(Callback cb) {
165    QuarantineBatch *b = (QuarantineBatch *)cb.Allocate(sizeof(*b));
166    b->count = 0;
167    b->size = 0;
168    list_.push_back(b);
169    return b;
170  }
171};
172}  // namespace __sanitizer
173
174#endif  // #ifndef SANITIZER_QUARANTINE_H
175