348 lines
11 KiB
C++
348 lines
11 KiB
C++
/*
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* Copyright (C) 2007 The Android Open Source Project
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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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* http://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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#ifndef _LIBS_UTILS_THREADS_H
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#define _LIBS_UTILS_THREADS_H
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#include <stdint.h>
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#include <sys/types.h>
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#include <time.h>
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// ------------------------------------------------------------------
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// C API
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef void* android_thread_id_t;
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typedef int (*android_thread_func_t)(void*);
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enum {
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/*
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* ***********************************************
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* ** Keep in sync with android.os.Process.java **
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* ***********************************************
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*
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* This maps directly to the "nice" priorites we use in Android.
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* A thread priority should be chosen inverse-proportinally to
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* the amount of work the thread is expected to do. The more work
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* a thread will do, the less favorable priority it should get so that
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* it doesn't starve the system. Threads not behaving properly might
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* be "punished" by the kernel.
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* Use the levels below when appropriate. Intermediate values are
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* acceptable, preferably use the {MORE|LESS}_FAVORABLE constants below.
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*/
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ANDROID_PRIORITY_LOWEST = 19,
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/* use for background tasks */
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ANDROID_PRIORITY_BACKGROUND = 10,
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/* most threads run at normal priority */
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ANDROID_PRIORITY_NORMAL = 0,
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/* threads currently running a UI that the user is interacting with */
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ANDROID_PRIORITY_FOREGROUND = -2,
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/* the main UI thread has a slightly more favorable priority */
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ANDROID_PRIORITY_DISPLAY = -4,
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/* ui service treads might want to run at a urgent display (uncommon) */
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ANDROID_PRIORITY_URGENT_DISPLAY = -8,
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/* all normal audio threads */
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ANDROID_PRIORITY_AUDIO = -16,
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/* service audio threads (uncommon) */
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ANDROID_PRIORITY_URGENT_AUDIO = -19,
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/* should never be used in practice. regular process might not
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* be allowed to use this level */
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ANDROID_PRIORITY_HIGHEST = -20,
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ANDROID_PRIORITY_DEFAULT = ANDROID_PRIORITY_NORMAL,
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ANDROID_PRIORITY_MORE_FAVORABLE = -1,
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ANDROID_PRIORITY_LESS_FAVORABLE = +1,
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};
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// Create and run a new thread.
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extern int androidCreateThread(android_thread_func_t, void *);
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// Create thread with lots of parameters
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extern int androidCreateThreadEtc(android_thread_func_t entryFunction,
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void *userData,
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const char* threadName,
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int32_t threadPriority,
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size_t threadStackSize,
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android_thread_id_t *threadId);
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// Get some sort of unique identifier for the current thread.
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extern android_thread_id_t androidGetThreadId();
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// Low-level thread creation -- never creates threads that can
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// interact with the Java VM.
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extern int androidCreateRawThreadEtc(android_thread_func_t entryFunction,
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void *userData,
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const char* threadName,
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int32_t threadPriority,
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size_t threadStackSize,
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android_thread_id_t *threadId);
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// Used by the Java Runtime to control how threads are created, so that
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// they can be proper and lovely Java threads.
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typedef int (*android_create_thread_fn)(android_thread_func_t entryFunction,
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void *userData,
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const char* threadName,
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int32_t threadPriority,
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size_t threadStackSize,
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android_thread_id_t *threadId);
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extern void androidSetCreateThreadFunc(android_create_thread_fn func);
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#ifdef __cplusplus
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}
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#endif
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// ------------------------------------------------------------------
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// C++ API
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#ifdef __cplusplus
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#include <utils/Errors.h>
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#include <utils/RefBase.h>
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#include <utils/Timers.h>
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namespace android {
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typedef android_thread_id_t thread_id_t;
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typedef android_thread_func_t thread_func_t;
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enum {
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PRIORITY_LOWEST = ANDROID_PRIORITY_LOWEST,
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PRIORITY_BACKGROUND = ANDROID_PRIORITY_BACKGROUND,
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PRIORITY_NORMAL = ANDROID_PRIORITY_NORMAL,
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PRIORITY_FOREGROUND = ANDROID_PRIORITY_FOREGROUND,
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PRIORITY_DISPLAY = ANDROID_PRIORITY_DISPLAY,
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PRIORITY_URGENT_DISPLAY = ANDROID_PRIORITY_URGENT_DISPLAY,
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PRIORITY_AUDIO = ANDROID_PRIORITY_AUDIO,
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PRIORITY_URGENT_AUDIO = ANDROID_PRIORITY_URGENT_AUDIO,
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PRIORITY_HIGHEST = ANDROID_PRIORITY_HIGHEST,
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PRIORITY_DEFAULT = ANDROID_PRIORITY_DEFAULT,
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PRIORITY_MORE_FAVORABLE = ANDROID_PRIORITY_MORE_FAVORABLE,
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PRIORITY_LESS_FAVORABLE = ANDROID_PRIORITY_LESS_FAVORABLE,
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};
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// Create and run a new thread.
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inline bool createThread(thread_func_t f, void *a) {
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return androidCreateThread(f, a) ? true : false;
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}
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// Create thread with lots of parameters
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inline bool createThreadEtc(thread_func_t entryFunction,
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void *userData,
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const char* threadName = "android:unnamed_thread",
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int32_t threadPriority = PRIORITY_DEFAULT,
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size_t threadStackSize = 0,
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thread_id_t *threadId = 0)
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{
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return androidCreateThreadEtc(entryFunction, userData, threadName,
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threadPriority, threadStackSize, threadId) ? true : false;
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}
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// Get some sort of unique identifier for the current thread.
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inline thread_id_t getThreadId() {
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return androidGetThreadId();
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}
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/*
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* Simple mutex class. The implementation is system-dependent.
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*
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* The mutex must be unlocked by the thread that locked it. They are not
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* recursive, i.e. the same thread can't lock it multiple times.
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*/
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class Mutex {
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public:
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Mutex();
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Mutex(const char* name);
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~Mutex();
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// lock or unlock the mutex
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status_t lock();
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void unlock();
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// lock if possible; returns 0 on success, error otherwise
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status_t tryLock();
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// Manages the mutex automatically. It'll be locked when Autolock is
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// constructed and released when Autolock goes out of scope.
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class Autolock {
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public:
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inline Autolock(Mutex& mutex) : mpMutex(&mutex) { mutex.lock(); }
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inline Autolock(Mutex* mutex) : mpMutex(mutex) { mutex->lock(); }
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inline ~Autolock() { mpMutex->unlock(); }
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private:
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Mutex* mpMutex;
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};
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private:
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friend class Condition;
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// A mutex cannot be copied
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Mutex(const Mutex&);
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Mutex& operator = (const Mutex&);
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void _init();
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void* mState;
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};
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/*
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* Automatic mutex. Declare one of these at the top of a function.
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* When the function returns, it will go out of scope, and release the
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* mutex.
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*/
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typedef Mutex::Autolock AutoMutex;
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/*
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* Condition variable class. The implementation is system-dependent.
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*
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* Condition variables are paired up with mutexes. Lock the mutex,
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* call wait(), then either re-wait() if things aren't quite what you want,
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* or unlock the mutex and continue. All threads calling wait() must
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* use the same mutex for a given Condition.
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*/
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class Condition {
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public:
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Condition();
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~Condition();
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// Wait on the condition variable. Lock the mutex before calling.
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status_t wait(Mutex& mutex);
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// Wait on the condition variable until the given time. Lock the mutex
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// before calling.
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status_t wait(Mutex& mutex, nsecs_t abstime);
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// same with relative timeout
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status_t waitRelative(Mutex& mutex, nsecs_t reltime);
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// Signal the condition variable, allowing one thread to continue.
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void signal();
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// Signal the condition variable, allowing all threads to continue.
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void broadcast();
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private:
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void* mState;
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};
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/*
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* Read/write lock. The resource can have multiple readers or one writer,
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* but can't be read and written at the same time.
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*
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* The same thread should not call a lock function while it already has
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* a lock. (Should be okay for multiple readers.)
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*/
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class ReadWriteLock {
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public:
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ReadWriteLock()
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: mNumReaders(0), mNumWriters(0)
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{}
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~ReadWriteLock() {}
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void lockForRead();
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bool tryLockForRead();
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void unlockForRead();
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void lockForWrite();
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bool tryLockForWrite();
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void unlockForWrite();
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private:
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int mNumReaders;
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int mNumWriters;
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Mutex mLock;
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Condition mReadWaiter;
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Condition mWriteWaiter;
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#if defined(PRINT_RENDER_TIMES)
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DurationTimer mDebugTimer;
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#endif
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};
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/*
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* This is our spiffy thread object!
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*/
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class Thread : virtual public RefBase
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{
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public:
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// Create a Thread object, but doesn't create or start the associated
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// thread. See the run() method.
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Thread(bool canCallJava = true);
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virtual ~Thread();
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// Start the thread in threadLoop() which needs to be implemented.
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virtual status_t run( const char* name = 0,
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int32_t priority = PRIORITY_DEFAULT,
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size_t stack = 0);
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// Ask this object's thread to exit. This function is asynchronous, when the
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// function returns the thread might still be running. Of course, this
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// function can be called from a different thread.
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virtual void requestExit();
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// Good place to do one-time initializations
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virtual status_t readyToRun();
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// Call requestExit() and wait until this object's thread exits.
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// BE VERY CAREFUL of deadlocks. In particular, it would be silly to call
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// this function from this object's thread. Will return WOULD_BLOCK in
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// that case.
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status_t requestExitAndWait();
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protected:
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// exitPending() returns true if requestExit() has been called.
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bool exitPending() const;
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private:
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// Derived class must implemtent threadLoop(). The thread starts its life
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// here. There are two ways of using the Thread object:
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// 1) loop: if threadLoop() returns true, it will be called again if
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// requestExit() wasn't called.
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// 2) once: if threadLoop() returns false, the thread will exit upon return.
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virtual bool threadLoop() = 0;
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private:
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Thread& operator=(const Thread&);
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static int _threadLoop(void* user);
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const bool mCanCallJava;
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thread_id_t mThread;
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Mutex mLock;
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Condition mThreadExitedCondition;
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status_t mStatus;
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volatile bool mExitPending;
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volatile bool mRunning;
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sp<Thread> mHoldSelf;
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};
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}; // namespace android
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#endif // __cplusplus
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#endif // _LIBS_UTILS_THREADS_H
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