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 18 namespace scudo { 19 20 // Memory allocator statistics 21 enum StatType { StatAllocated, StatFree, StatMapped, StatCount }; 22 23 typedef 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. 30 class LocalStats { 31 public: 32 void init() { 33 for (uptr I = 0; I < StatCount; I++) 34 DCHECK_EQ(get(static_cast<StatType>(I)), 0U); 35 } 36 37 void add(StatType I, uptr V) { 38 V += atomic_load_relaxed(&StatsArray[I]); 39 atomic_store_relaxed(&StatsArray[I], V); 40 } 41 42 void sub(StatType I, uptr V) { 43 V = atomic_load_relaxed(&StatsArray[I]) - V; 44 atomic_store_relaxed(&StatsArray[I], V); 45 } 46 47 void set(StatType I, uptr V) { atomic_store_relaxed(&StatsArray[I], V); } 48 49 uptr get(StatType I) const { return atomic_load_relaxed(&StatsArray[I]); } 50 51 LocalStats *Next = nullptr; 52 LocalStats *Prev = nullptr; 53 54 private: 55 atomic_uptr StatsArray[StatCount] = {}; 56 }; 57 58 // Global stats, used for aggregation and querying. 59 class GlobalStats : public LocalStats { 60 public: 61 void init() { LocalStats::init(); } 62 63 void link(LocalStats *S) { 64 ScopedLock L(Mutex); 65 StatsList.push_back(S); 66 } 67 68 void unlink(LocalStats *S) { 69 ScopedLock L(Mutex); 70 StatsList.remove(S); 71 for (uptr I = 0; I < StatCount; I++) 72 add(static_cast<StatType>(I), S->get(static_cast<StatType>(I))); 73 } 74 75 void get(uptr *S) const { 76 ScopedLock L(Mutex); 77 for (uptr I = 0; I < StatCount; I++) 78 S[I] = LocalStats::get(static_cast<StatType>(I)); 79 for (const auto &Stats : StatsList) { 80 for (uptr I = 0; I < StatCount; I++) 81 S[I] += Stats.get(static_cast<StatType>(I)); 82 } 83 // All stats must be non-negative. 84 for (uptr I = 0; I < StatCount; I++) 85 S[I] = static_cast<sptr>(S[I]) >= 0 ? S[I] : 0; 86 } 87 88 void lock() { Mutex.lock(); } 89 void unlock() { Mutex.unlock(); } 90 91 void disable() { lock(); } 92 void enable() { unlock(); } 93 94 private: 95 mutable HybridMutex Mutex; 96 DoublyLinkedList<LocalStats> StatsList; 97 }; 98 99 } // namespace scudo 100 101 #endif // SCUDO_STATS_H_ 102