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72c9c808cd
Export `GetStallSpecs` as `mozilla::GetAllocatorStallSpecs`, when it exists. Differential Revision: https://phabricator.services.mozilla.com/D165430
76 lines
2.1 KiB
C++
76 lines
2.1 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozjemalloc_utils_h
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#define mozjemalloc_utils_h
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#include <optional>
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#include <type_traits>
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#if defined(MOZ_MEMORY) && defined(XP_WIN)
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# include "mozmemory_wrap.h"
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#endif
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namespace mozilla {
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namespace detail {
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// Helper for StallAndRetry error messages.
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template <typename T>
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constexpr bool is_std_optional = false;
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template <typename T>
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constexpr bool is_std_optional<std::optional<T>> = true;
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} // namespace detail
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struct StallSpecs {
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// Maximum number of retry-attempts before giving up.
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size_t maxAttempts;
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// Delay time between successive events.
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size_t delayMs;
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// Retry a fallible operation until it succeeds or until we've run out of
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// retries.
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//
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// Note that this invokes `aDelayFunc` immediately upon being called! It's
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// intended for use in the unhappy path, after an initial attempt has failed.
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//
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// The function type here may be read:
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// ```
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// fn StallAndRetry<R>(
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// delay_func: impl Fn(usize) -> (),
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// operation: impl Fn() -> Option<R>,
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// ) -> Option<R>;
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// ```
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//
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template <typename DelayFunc, typename OpFunc>
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auto StallAndRetry(DelayFunc&& aDelayFunc, OpFunc&& aOperation) const
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-> decltype(aOperation()) {
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{
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// Explicit typecheck for OpFunc, to provide an explicit error message.
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using detail::is_std_optional;
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static_assert(is_std_optional<decltype(aOperation())>,
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"aOperation() must return std::optional");
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// (clang's existing error messages suffice for aDelayFunc.)
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}
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for (size_t i = 0; i < maxAttempts; ++i) {
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aDelayFunc(delayMs);
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if (const auto opt = aOperation()) {
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return opt;
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}
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}
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return std::nullopt;
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}
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};
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#if defined(MOZ_MEMORY) && defined(XP_WIN)
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MOZ_JEMALLOC_API StallSpecs GetAllocatorStallSpecs();
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#endif
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} // namespace mozilla
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#endif // mozjemalloc_utils_h
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