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Diffstat (limited to 'lib/scudo/standalone/stats.h')
-rw-r--r-- | lib/scudo/standalone/stats.h | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/lib/scudo/standalone/stats.h b/lib/scudo/standalone/stats.h new file mode 100644 index 000000000..7fb9c9ed6 --- /dev/null +++ b/lib/scudo/standalone/stats.h @@ -0,0 +1,105 @@ +//===-- stats.h -------------------------------------------------*- C++ -*-===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +#ifndef SCUDO_STATS_H_ +#define SCUDO_STATS_H_ + +#include "atomic_helpers.h" +#include "mutex.h" + +#include <string.h> + +namespace scudo { + +// Memory allocator statistics +enum StatType { StatAllocated, StatMapped, StatCount }; + +typedef uptr StatCounters[StatCount]; + +// Per-thread stats, live in per-thread cache. We use atomics so that the +// numbers themselves are consistent. But we don't use atomic_{add|sub} or a +// lock, because those are expensive operations , and we only care for the stats +// to be "somewhat" correct: eg. if we call GlobalStats::get while a thread is +// LocalStats::add'ing, this is OK, we will still get a meaningful number. +class LocalStats { +public: + void initLinkerInitialized() {} + void init() { memset(this, 0, sizeof(*this)); } + + void add(StatType I, uptr V) { + V += atomic_load_relaxed(&StatsArray[I]); + atomic_store_relaxed(&StatsArray[I], V); + } + + void sub(StatType I, uptr V) { + V = atomic_load_relaxed(&StatsArray[I]) - V; + atomic_store_relaxed(&StatsArray[I], V); + } + + void set(StatType I, uptr V) { atomic_store_relaxed(&StatsArray[I], V); } + + uptr get(StatType I) const { return atomic_load_relaxed(&StatsArray[I]); } + +private: + friend class GlobalStats; + atomic_uptr StatsArray[StatCount]; + LocalStats *Next; + LocalStats *Prev; +}; + +// Global stats, used for aggregation and querying. +class GlobalStats : public LocalStats { +public: + void initLinkerInitialized() { + Next = this; + Prev = this; + } + void init() { + memset(this, 0, sizeof(*this)); + initLinkerInitialized(); + } + + void link(LocalStats *S) { + SpinMutexLock L(&Mutex); + S->Next = Next; + S->Prev = this; + Next->Prev = S; + Next = S; + } + + void unlink(LocalStats *S) { + SpinMutexLock L(&Mutex); + S->Prev->Next = S->Next; + S->Next->Prev = S->Prev; + for (uptr I = 0; I < StatCount; I++) + add(static_cast<StatType>(I), S->get(static_cast<StatType>(I))); + } + + void get(uptr *S) const { + memset(S, 0, StatCount * sizeof(uptr)); + SpinMutexLock L(&Mutex); + const LocalStats *Stats = this; + for (;;) { + for (uptr I = 0; I < StatCount; I++) + S[I] += Stats->get(static_cast<StatType>(I)); + Stats = Stats->Next; + if (Stats == this) + break; + } + // All stats must be non-negative. + for (uptr I = 0; I < StatCount; I++) + S[I] = static_cast<sptr>(S[I]) >= 0 ? S[I] : 0; + } + +private: + mutable StaticSpinMutex Mutex; +}; + +} // namespace scudo + +#endif // SCUDO_STATS_H_ |