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//===-- 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 "list.h"
#include "mutex.h"
#include <string.h>
namespace scudo {
// Memory allocator statistics
enum StatType { StatAllocated, StatFree, 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 init() {
for (uptr I = 0; I < StatCount; I++)
DCHECK_EQ(get(static_cast<StatType>(I)), 0U);
}
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]); }
LocalStats *Next = nullptr;
LocalStats *Prev = nullptr;
private:
atomic_uptr StatsArray[StatCount] = {};
};
// Global stats, used for aggregation and querying.
class GlobalStats : public LocalStats {
public:
void init() { LocalStats::init(); }
void link(LocalStats *S) {
ScopedLock L(Mutex);
StatsList.push_back(S);
}
void unlink(LocalStats *S) {
ScopedLock L(Mutex);
StatsList.remove(S);
for (uptr I = 0; I < StatCount; I++)
add(static_cast<StatType>(I), S->get(static_cast<StatType>(I)));
}
void get(uptr *S) const {
ScopedLock L(Mutex);
for (uptr I = 0; I < StatCount; I++)
S[I] = LocalStats::get(static_cast<StatType>(I));
for (const auto &Stats : StatsList) {
for (uptr I = 0; I < StatCount; I++)
S[I] += Stats.get(static_cast<StatType>(I));
}
// All stats must be non-negative.
for (uptr I = 0; I < StatCount; I++)
S[I] = static_cast<sptr>(S[I]) >= 0 ? S[I] : 0;
}
void lock() { Mutex.lock(); }
void unlock() { Mutex.unlock(); }
void disable() { lock(); }
void enable() { unlock(); }
private:
mutable HybridMutex Mutex;
DoublyLinkedList<LocalStats> StatsList;
};
} // namespace scudo
#endif // SCUDO_STATS_H_
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