1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef INCLUDE_PERFETTO_BASE_TASK_RUNNER_H_ 18 #define INCLUDE_PERFETTO_BASE_TASK_RUNNER_H_ 19 20 #include <stdint.h> 21 22 #include <functional> 23 24 #include "perfetto/base/export.h" 25 #include "perfetto/base/platform_handle.h" 26 27 namespace perfetto { 28 namespace base { 29 30 // A generic interface to allow the library clients to interleave the execution 31 // of the tracing internals in their runtime environment. 32 // The expectation is that all tasks, which are queued either via PostTask() or 33 // AddFileDescriptorWatch(), are executed on the same sequence (either on the 34 // same thread, or on a thread pool that gives sequencing guarantees). 35 // 36 // Tasks are never executed synchronously inside PostTask and there is a full 37 // memory barrier between tasks. 38 // 39 // All methods of this interface can be called from any thread. 40 class PERFETTO_EXPORT TaskRunner { 41 public: 42 virtual ~TaskRunner(); 43 44 // Schedule a task for immediate execution. Immediate tasks are always 45 // executed in the order they are posted. Can be called from any thread. 46 virtual void PostTask(std::function<void()>) = 0; 47 48 // Schedule a task for execution after |delay_ms|. Note that there is no 49 // strict ordering guarantee between immediate and delayed tasks. Can be 50 // called from any thread. 51 virtual void PostDelayedTask(std::function<void()>, uint32_t delay_ms) = 0; 52 53 // Schedule a task to run when the handle becomes readable. The same handle 54 // can only be monitored by one function. Note that this function only needs 55 // to be implemented on platforms where the built-in ipc framework is used. 56 // Can be called from any thread. 57 // TODO(skyostil): Refactor this out of the shared interface. 58 virtual void AddFileDescriptorWatch(PlatformHandle, 59 std::function<void()>) = 0; 60 61 // Remove a previously scheduled watch for the handle. If this is run on the 62 // target thread of this TaskRunner, guarantees that the task registered to 63 // this handle will not be executed after this function call. 64 // Can be called from any thread. 65 virtual void RemoveFileDescriptorWatch(PlatformHandle) = 0; 66 67 // Checks if the current thread is the same thread where the TaskRunner's task 68 // run. This allows single threaded task runners (like the ones used in 69 // perfetto) to inform the caller that anything posted will run on the same 70 // thread/sequence. This can allow some callers to skip PostTask and instead 71 // directly execute the code. Can be called from any thread. 72 virtual bool RunsTasksOnCurrentThread() const = 0; 73 }; 74 75 } // namespace base 76 } // namespace perfetto 77 78 #endif // INCLUDE_PERFETTO_BASE_TASK_RUNNER_H_ 79