1//===-- stats.h -------------------------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef SCUDO_STATS_H_
10#define SCUDO_STATS_H_
11
12#include "atomic_helpers.h"
13#include "list.h"
14#include "mutex.h"
15
16#include <string.h>
17
18namespace scudo {
19
20// Memory allocator statistics
21enum StatType { StatAllocated, StatFree, StatMapped, StatCount };
22
23typedef uptr StatCounters[StatCount];
24
25// Per-thread stats, live in per-thread cache. We use atomics so that the
26// numbers themselves are consistent. But we don't use atomic_{add|sub} or a
27// lock, because those are expensive operations , and we only care for the stats
28// to be "somewhat" correct: eg. if we call GlobalStats::get while a thread is
29// LocalStats::add'ing, this is OK, we will still get a meaningful number.
30class LocalStats {
31public:
32  void initLinkerInitialized() {}
33  void init() { memset(this, 0, sizeof(*this)); }
34
35  void add(StatType I, uptr V) {
36    V += atomic_load_relaxed(&StatsArray[I]);
37    atomic_store_relaxed(&StatsArray[I], V);
38  }
39
40  void sub(StatType I, uptr V) {
41    V = atomic_load_relaxed(&StatsArray[I]) - V;
42    atomic_store_relaxed(&StatsArray[I], V);
43  }
44
45  void set(StatType I, uptr V) { atomic_store_relaxed(&StatsArray[I], V); }
46
47  uptr get(StatType I) const { return atomic_load_relaxed(&StatsArray[I]); }
48
49  LocalStats *Next;
50  LocalStats *Prev;
51
52private:
53  atomic_uptr StatsArray[StatCount];
54};
55
56// Global stats, used for aggregation and querying.
57class GlobalStats : public LocalStats {
58public:
59  void initLinkerInitialized() {}
60  void init() {
61    LocalStats::init();
62    Mutex.init();
63    StatsList = {};
64    initLinkerInitialized();
65  }
66
67  void link(LocalStats *S) {
68    ScopedLock L(Mutex);
69    StatsList.push_back(S);
70  }
71
72  void unlink(LocalStats *S) {
73    ScopedLock L(Mutex);
74    StatsList.remove(S);
75    for (uptr I = 0; I < StatCount; I++)
76      add(static_cast<StatType>(I), S->get(static_cast<StatType>(I)));
77  }
78
79  void get(uptr *S) const {
80    ScopedLock L(Mutex);
81    for (uptr I = 0; I < StatCount; I++)
82      S[I] = LocalStats::get(static_cast<StatType>(I));
83    for (const auto &Stats : StatsList) {
84      for (uptr I = 0; I < StatCount; I++)
85        S[I] += Stats.get(static_cast<StatType>(I));
86    }
87    // All stats must be non-negative.
88    for (uptr I = 0; I < StatCount; I++)
89      S[I] = static_cast<sptr>(S[I]) >= 0 ? S[I] : 0;
90  }
91
92  void disable() { Mutex.lock(); }
93  void enable() { Mutex.unlock(); }
94
95private:
96  mutable HybridMutex Mutex;
97  DoublyLinkedList<LocalStats> StatsList;
98};
99
100} // namespace scudo
101
102#endif // SCUDO_STATS_H_
103