cf6ab6bb2b
- b527a3e4b36b644ac424e3c525b1cd393f6f6c40 Fix some typos in the usage examples by Jorg Brown <jorg@google.com> - 82be4a9adf3bb0ddafc0d46274969c99afffe870 Fix typo in optional.h comment. by Abseil Team <absl-team@google.com> - d6ee63bf8fc51fba074c23b33cebc28c808d7f07 Remove internal-only identifiers from code. by Daniel Katz <katzdm@google.com> - f9c3ad2f0d73f53b21603638af8b4bed636e79f4 Use easier understandable names for absl::StartsWith and ... by Abseil Team <absl-team@google.com> - 7c16c14fefee89c927b8789d6043c4691bcffc9b Add -Wno-missing-prototypes back to the LLVM copts. by Derek Mauro <dmauro@google.com> - 2f4b7d2e50c7023240242f1e15db60ccd7e8768d IWYU | absl/strings by Juemin Yang <jueminyang@google.com> - a99cbcc1daa34a2d6a2bb26de275e05173cc77e9 IWYU | absl/type by Juemin Yang <jueminyang@google.com> - 12e1146d0fc76c071d7e0ebaabb62f0a984fae66 Use LLVM_FLAGS and LLVM_TEST_FLAGS when --compiler=llvm. by Derek Mauro <dmauro@google.com> - cd6bea616abda558d0bace5bd77455662a233688 IWYU | absl/debugging by Juemin Yang <jueminyang@google.com> - d9a7382e59d46a8581b6b7a31cd5a48bb89326e9 IWYU | absl/synchronization by Juemin Yang <jueminyang@google.com> - 07ec7d6d5a4a666f4183c5d0ed9c342baa7b24bc IWYU | absl/numeric by Juemin Yang <jueminyang@google.com> - 12bfe40051f4270f8707e191af5652f83f2f750c Remove the RoundTrip{Float,Double}ToBuffer routines from ... by Jorg Brown <jorg@google.com> - eeb4fd67c9d97f66cb9475c3c5e51ab132f1c810 Adds conversion functions for converting between absl/tim... by Greg Miller <jgm@google.com> - 59a2108d05d4ea85dc5cc11e49b2cd2335d4295a Change Substitute to use %.6g formatting rather than 15/1... by Jorg Brown <jorg@google.com> - 394becb48e0fcd161642cdaac5120d32567e0ef8 IWYU | absl/meta by Juemin Yang <jueminyang@google.com> - 1e5da6e8da336699b2469dcf6dda025b9b0ec4c9 Rewrite atomic_hook.h to not use std::atomic<T*> under Wi... by Greg Falcon <gfalcon@google.com> GitOrigin-RevId: b527a3e4b36b644ac424e3c525b1cd393f6f6c40 Change-Id: I14e331d91c956ef045ac7927091a9f179716de0c
104 lines
3.9 KiB
C++
104 lines
3.9 KiB
C++
// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// Core interfaces and definitions used by by low-level interfaces such as
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// SpinLock.
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#ifndef ABSL_BASE_INTERNAL_LOW_LEVEL_SCHEDULING_H_
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#define ABSL_BASE_INTERNAL_LOW_LEVEL_SCHEDULING_H_
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#include "absl/base/internal/scheduling_mode.h"
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#include "absl/base/macros.h"
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// The following two declarations exist so SchedulingGuard may friend them with
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// the appropriate language linkage. These callbacks allow libc internals, such
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// as function level statics, to schedule cooperatively when locking.
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extern "C" bool __google_disable_rescheduling(void);
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extern "C" void __google_enable_rescheduling(bool disable_result);
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namespace absl {
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namespace base_internal {
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class SchedulingHelper; // To allow use of SchedulingGuard.
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class SpinLock; // To allow use of SchedulingGuard.
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// SchedulingGuard
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// Provides guard semantics that may be used to disable cooperative rescheduling
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// of the calling thread within specific program blocks. This is used to
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// protect resources (e.g. low-level SpinLocks or Domain code) that cooperative
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// scheduling depends on.
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//
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// Domain implementations capable of rescheduling in reaction to involuntary
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// kernel thread actions (e.g blocking due to a pagefault or syscall) must
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// guarantee that an annotated thread is not allowed to (cooperatively)
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// reschedule until the annotated region is complete.
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//
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// It is an error to attempt to use a cooperatively scheduled resource (e.g.
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// Mutex) within a rescheduling-disabled region.
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//
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// All methods are async-signal safe.
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class SchedulingGuard {
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public:
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// Returns true iff the calling thread may be cooperatively rescheduled.
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static bool ReschedulingIsAllowed();
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private:
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// Disable cooperative rescheduling of the calling thread. It may still
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// initiate scheduling operations (e.g. wake-ups), however, it may not itself
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// reschedule. Nestable. The returned result is opaque, clients should not
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// attempt to interpret it.
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// REQUIRES: Result must be passed to a pairing EnableScheduling().
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static bool DisableRescheduling();
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// Marks the end of a rescheduling disabled region, previously started by
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// DisableRescheduling().
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// REQUIRES: Pairs with innermost call (and result) of DisableRescheduling().
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static void EnableRescheduling(bool disable_result);
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// A scoped helper for {Disable, Enable}Rescheduling().
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// REQUIRES: destructor must run in same thread as constructor.
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struct ScopedDisable {
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ScopedDisable() { disabled = SchedulingGuard::DisableRescheduling(); }
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~ScopedDisable() { SchedulingGuard::EnableRescheduling(disabled); }
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bool disabled;
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};
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// Access to SchedulingGuard is explicitly white-listed.
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friend class SchedulingHelper;
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friend class SpinLock;
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SchedulingGuard(const SchedulingGuard&) = delete;
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SchedulingGuard& operator=(const SchedulingGuard&) = delete;
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};
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//------------------------------------------------------------------------------
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// End of public interfaces.
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//------------------------------------------------------------------------------
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inline bool SchedulingGuard::ReschedulingIsAllowed() {
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return false;
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}
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inline bool SchedulingGuard::DisableRescheduling() {
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return false;
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}
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inline void SchedulingGuard::EnableRescheduling(bool /* disable_result */) {
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return;
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}
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} // namespace base_internal
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} // namespace absl
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#endif // ABSL_BASE_INTERNAL_LOW_LEVEL_SCHEDULING_H_
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