54 lines
2.3 KiB
C++
54 lines
2.3 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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// https://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_SCHEDULING_MODE_H_
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#define ABSL_BASE_INTERNAL_SCHEDULING_MODE_H_
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namespace absl {
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namespace base_internal {
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// Used to describe how a thread may be scheduled. Typically associated with
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// the declaration of a resource supporting synchronized access.
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//
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// SCHEDULE_COOPERATIVE_AND_KERNEL:
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// Specifies that when waiting, a cooperative thread (e.g. a Fiber) may
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// reschedule (using base::scheduling semantics); allowing other cooperative
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// threads to proceed.
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//
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// SCHEDULE_KERNEL_ONLY: (Also described as "non-cooperative")
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// Specifies that no cooperative scheduling semantics may be used, even if the
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// current thread is itself cooperatively scheduled. This means that
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// cooperative threads will NOT allow other cooperative threads to execute in
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// their place while waiting for a resource of this type. Host operating system
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// semantics (e.g. a futex) may still be used.
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//
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// When optional, clients should strongly prefer SCHEDULE_COOPERATIVE_AND_KERNEL
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// by default. SCHEDULE_KERNEL_ONLY should only be used for resources on which
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// base::scheduling (e.g. the implementation of a Scheduler) may depend.
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//
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// NOTE: Cooperative resources may not be nested below non-cooperative ones.
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// This means that it is invalid to to acquire a SCHEDULE_COOPERATIVE_AND_KERNEL
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// resource if a SCHEDULE_KERNEL_ONLY resource is already held.
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enum SchedulingMode {
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SCHEDULE_KERNEL_ONLY = 0, // Allow scheduling only the host OS.
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SCHEDULE_COOPERATIVE_AND_KERNEL, // Also allow cooperative scheduling.
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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_SCHEDULING_MODE_H_
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