| // 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. | |
| 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 | |