1 /* 2 * Copyright (C) 2019 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_TRACING_PLATFORM_H_ 18 #define INCLUDE_PERFETTO_TRACING_PLATFORM_H_ 19 20 #include <stddef.h> 21 #include <stdint.h> 22 23 #include <functional> 24 #include <memory> 25 #include <string> 26 27 #include "perfetto/base/export.h" 28 #include "perfetto/base/logging.h" 29 #include "perfetto/base/proc_utils.h" 30 #include "perfetto/base/thread_utils.h" 31 #include "perfetto/tracing/tracing.h" 32 33 namespace perfetto { 34 35 namespace base { 36 class TaskRunner; 37 } // namespace base 38 39 // This abstract class is used to abstract dependencies on platform-specific 40 // primitives that cannot be implemented by the perfetto codebase and must be 41 // provided or overridden by the embedder. 42 // This is, for instance, for cases where we want to use some particular 43 // base:: class in Chrome and provide instead POSIX fallbacks for other 44 // embedders. 45 46 // Base class for thread-local objects. This is to get a basic object vtable and 47 // delegate destruction to the embedder. See Platform::CreateThreadLocalObject. 48 class PERFETTO_EXPORT_COMPONENT PlatformThreadLocalObject { 49 public: 50 // Implemented by perfetto internal code. The embedder must call this when 51 // implementing GetOrCreateThreadLocalObject() to create an instance for the 52 // first time on each thread. 53 static std::unique_ptr<PlatformThreadLocalObject> CreateInstance(); 54 virtual ~PlatformThreadLocalObject(); 55 }; 56 57 class PERFETTO_EXPORT_COMPONENT Platform { 58 public: 59 // Embedders can use this unless they have custom needs (e.g. Chrome wanting 60 // to use its own base class for TLS). 61 static Platform* GetDefaultPlatform(); 62 63 // Embedders can call this to set process ID in those cases where getpid() 64 // returns incorrect values (e.g. for sandboxed processes in Chromium). 65 // Should only be called once, before tracing has been initialized. SetCurrentProcessId(base::PlatformProcessId process_id)66 static void SetCurrentProcessId(base::PlatformProcessId process_id) { 67 PERFETTO_CHECK(!process_id_); 68 PERFETTO_DCHECK(!Tracing::IsInitialized()); 69 process_id_ = process_id; 70 } 71 72 // Returns process ID previously set by SetCurrentProcessId, or the process 73 // ID provided by the OS if no custom ID was provided. GetCurrentProcessId()74 static base::PlatformProcessId GetCurrentProcessId() { 75 if (process_id_) 76 return process_id_; 77 return base::GetProcessId(); 78 } 79 80 virtual ~Platform(); 81 82 // Creates a thread-local object. The embedder must: 83 // - Create an instance per-thread calling ThreadLocalObject::CreateInstance. 84 // - Own the lifetime of the returned object as long as the thread is alive. 85 // - Destroy it when the thread exits. 86 // Perfetto requires only one thread-local object overall (obviously, one 87 // instance per-thread) from the embedder. 88 using ThreadLocalObject = ::perfetto::PlatformThreadLocalObject; 89 virtual ThreadLocalObject* GetOrCreateThreadLocalObject() = 0; 90 91 // Creates a sequenced task runner. The easiest implementation is to create 92 // a new thread (e.g. use base::ThreadTaskRunner) but this can also be 93 // implemented in some more clever way (e.g. using chromiums's scheduler). 94 struct CreateTaskRunnerArgs { 95 // Optional. Sets the name to the newly created task runner. In the default 96 // PosixPlatform implementation this causes a pthread_setname_np(). This is 97 // only for ease of debugging, it does not affect the tracing behavior. 98 std::string name_for_debugging; 99 }; 100 virtual std::unique_ptr<base::TaskRunner> CreateTaskRunner( 101 const CreateTaskRunnerArgs&) = 0; 102 103 // Used to derive the producer name. Mostly relevant when using the 104 // kSystemBackend mode. It can be an arbitrary string when using the 105 // in-process mode. 106 virtual std::string GetCurrentProcessName() = 0; 107 108 // Tear down any persistent platform state (e.g., TLS variables). The platform 109 // interface must not be used after calling this function. 110 virtual void Shutdown(); 111 112 // Returns the thread ID provided by the OS by default. Chromium uses 113 // different thread IDs on some platforms, so it needs the ability to 114 // override this method. 115 virtual base::PlatformThreadId GetCurrentThreadId(); 116 117 private: 118 static base::PlatformProcessId process_id_; 119 }; 120 121 } // namespace perfetto 122 123 #endif // INCLUDE_PERFETTO_TRACING_PLATFORM_H_ 124