// Copyright 2017 The Abseil Authors. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // https://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. // // Core interfaces and definitions used by by low-level interfaces such as // SpinLock. #ifndef ABSL_BASE_INTERNAL_SCHEDULING_MODE_H_ #define ABSL_BASE_INTERNAL_SCHEDULING_MODE_H_ #include "absl/base/config.h" namespace absl { ABSL_NAMESPACE_BEGIN namespace base_internal { // Used to describe how a thread may be scheduled. Typically associated with // the declaration of a resource supporting synchronized access. // // SCHEDULE_COOPERATIVE_AND_KERNEL: // Specifies that when waiting, a cooperative thread (e.g. a Fiber) may // reschedule (using base::scheduling semantics); allowing other cooperative // threads to proceed. // // SCHEDULE_KERNEL_ONLY: (Also described as "non-cooperative") // Specifies that no cooperative scheduling semantics may be used, even if the // current thread is itself cooperatively scheduled. This means that // cooperative threads will NOT allow other cooperative threads to execute in // their place while waiting for a resource of this type. Host operating system // semantics (e.g. a futex) may still be used. // // When optional, clients should strongly prefer SCHEDULE_COOPERATIVE_AND_KERNEL // by default. SCHEDULE_KERNEL_ONLY should only be used for resources on which // base::scheduling (e.g. the implementation of a Scheduler) may depend. // // NOTE: Cooperative resources may not be nested below non-cooperative ones. // This means that it is invalid to to acquire a SCHEDULE_COOPERATIVE_AND_KERNEL // resource if a SCHEDULE_KERNEL_ONLY resource is already held. enum SchedulingMode { SCHEDULE_KERNEL_ONLY = 0, // Allow scheduling only the host OS. SCHEDULE_COOPERATIVE_AND_KERNEL, // Also allow cooperative scheduling. }; } // namespace base_internal ABSL_NAMESPACE_END } // namespace absl #endif // ABSL_BASE_INTERNAL_SCHEDULING_MODE_H_