tsan_clock.h revision 1.1.1.4 
1//===-- tsan_clock.h --------------------------------------------*- C++ -*-===//
2//
3// This file is distributed under the University of Illinois Open Source
4// License. See LICENSE.TXT for details.
5//
6//===----------------------------------------------------------------------===//
7//
8// This file is a part of ThreadSanitizer (TSan), a race detector.
9//
10//===----------------------------------------------------------------------===//
11#ifndef TSAN_CLOCK_H
12#define TSAN_CLOCK_H
13
14#include "tsan_defs.h"
15#include "tsan_dense_alloc.h"
16
17namespace __tsan {
18
19struct ClockElem {
20  u64 epoch  : kClkBits;
21  u64 reused : 64 - kClkBits;
22};
23
24struct ClockBlock {
25  static const uptr kSize = 512;
26  static const uptr kTableSize = kSize / sizeof(u32);
27  static const uptr kClockCount = kSize / sizeof(ClockElem);
28
29  union {
30    u32       table[kTableSize];
31    ClockElem clock[kClockCount];
32  };
33
34  ClockBlock() {
35  }
36};
37
38typedef DenseSlabAlloc<ClockBlock, 1<<16, 1<<10> ClockAlloc;
39typedef DenseSlabAllocCache ClockCache;
40
41// The clock that lives in sync variables (mutexes, atomics, etc).
42class SyncClock {
43 public:
44  SyncClock();
45  ~SyncClock();
46
47  uptr size() const {
48    return size_;
49  }
50
51  u64 get(unsigned tid) const {
52    return elem(tid).epoch;
53  }
54
55  void Resize(ClockCache *c, uptr nclk);
56  void Reset(ClockCache *c);
57
58  void DebugDump(int(*printf)(const char *s, ...));
59
60 private:
61  friend struct ThreadClock;
62  static const uptr kDirtyTids = 2;
63
64  unsigned release_store_tid_;
65  unsigned release_store_reused_;
66  unsigned dirty_tids_[kDirtyTids];
67  // tab_ contains indirect pointer to a 512b block using DenseSlabAlloc.
68  // If size_ <= 64, then tab_ points to an array with 64 ClockElem's.
69  // Otherwise, tab_ points to an array with 128 u32 elements,
70  // each pointing to the second-level 512b block with 64 ClockElem's.
71  ClockBlock *tab_;
72  u32 tab_idx_;
73  u32 size_;
74
75  ClockElem &elem(unsigned tid) const;
76};
77
78// The clock that lives in threads.
79struct ThreadClock {
80 public:
81  typedef DenseSlabAllocCache Cache;
82
83  explicit ThreadClock(unsigned tid, unsigned reused = 0);
84
85  u64 get(unsigned tid) const {
86    DCHECK_LT(tid, kMaxTidInClock);
87    return clk_[tid].epoch;
88  }
89
90  void set(unsigned tid, u64 v);
91
92  void set(u64 v) {
93    DCHECK_GE(v, clk_[tid_].epoch);
94    clk_[tid_].epoch = v;
95  }
96
97  void tick() {
98    clk_[tid_].epoch++;
99  }
100
101  uptr size() const {
102    return nclk_;
103  }
104
105  void acquire(ClockCache *c, const SyncClock *src);
106  void release(ClockCache *c, SyncClock *dst) const;
107  void acq_rel(ClockCache *c, SyncClock *dst);
108  void ReleaseStore(ClockCache *c, SyncClock *dst) const;
109
110  void DebugReset();
111  void DebugDump(int(*printf)(const char *s, ...));
112
113 private:
114  static const uptr kDirtyTids = SyncClock::kDirtyTids;
115  const unsigned tid_;
116  const unsigned reused_;
117  u64 last_acquire_;
118  uptr nclk_;
119  ClockElem clk_[kMaxTidInClock];
120
121  bool IsAlreadyAcquired(const SyncClock *src) const;
122  void UpdateCurrentThread(SyncClock *dst) const;
123};
124
125}  // namespace __tsan
126
127#endif  // TSAN_CLOCK_H
128