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Diffstat (limited to '9/platforms/android-21/arch-arm/usr/include/android/looper.h')
-rw-r--r-- | 9/platforms/android-21/arch-arm/usr/include/android/looper.h | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/9/platforms/android-21/arch-arm/usr/include/android/looper.h b/9/platforms/android-21/arch-arm/usr/include/android/looper.h new file mode 100644 index 0000000..74c0383 --- /dev/null +++ b/9/platforms/android-21/arch-arm/usr/include/android/looper.h @@ -0,0 +1,256 @@ +/* + * Copyright (C) 2010 The Android Open Source Project + * + * 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 + * + * http://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. + */ + + +#ifndef ANDROID_LOOPER_H +#define ANDROID_LOOPER_H + +#ifdef __cplusplus +extern "C" { +#endif + +/** + * ALooper + * + * A looper is the state tracking an event loop for a thread. + * Loopers do not define event structures or other such things; rather + * they are a lower-level facility to attach one or more discrete objects + * listening for an event. An "event" here is simply data available on + * a file descriptor: each attached object has an associated file descriptor, + * and waiting for "events" means (internally) polling on all of these file + * descriptors until one or more of them have data available. + * + * A thread can have only one ALooper associated with it. + */ +struct ALooper; +typedef struct ALooper ALooper; + +/** + * Returns the looper associated with the calling thread, or NULL if + * there is not one. + */ +ALooper* ALooper_forThread(); + +enum { + /** + * Option for ALooper_prepare: this looper will accept calls to + * ALooper_addFd() that do not have a callback (that is provide NULL + * for the callback). In this case the caller of ALooper_pollOnce() + * or ALooper_pollAll() MUST check the return from these functions to + * discover when data is available on such fds and process it. + */ + ALOOPER_PREPARE_ALLOW_NON_CALLBACKS = 1<<0 +}; + +/** + * Prepares a looper associated with the calling thread, and returns it. + * If the thread already has a looper, it is returned. Otherwise, a new + * one is created, associated with the thread, and returned. + * + * The opts may be ALOOPER_PREPARE_ALLOW_NON_CALLBACKS or 0. + */ +ALooper* ALooper_prepare(int opts); + +enum { + /** + * Result from ALooper_pollOnce() and ALooper_pollAll(): + * The poll was awoken using wake() before the timeout expired + * and no callbacks were executed and no other file descriptors were ready. + */ + ALOOPER_POLL_WAKE = -1, + + /** + * Result from ALooper_pollOnce() and ALooper_pollAll(): + * One or more callbacks were executed. + */ + ALOOPER_POLL_CALLBACK = -2, + + /** + * Result from ALooper_pollOnce() and ALooper_pollAll(): + * The timeout expired. + */ + ALOOPER_POLL_TIMEOUT = -3, + + /** + * Result from ALooper_pollOnce() and ALooper_pollAll(): + * An error occurred. + */ + ALOOPER_POLL_ERROR = -4, +}; + +/** + * Acquire a reference on the given ALooper object. This prevents the object + * from being deleted until the reference is removed. This is only needed + * to safely hand an ALooper from one thread to another. + */ +void ALooper_acquire(ALooper* looper); + +/** + * Remove a reference that was previously acquired with ALooper_acquire(). + */ +void ALooper_release(ALooper* looper); + +/** + * Flags for file descriptor events that a looper can monitor. + * + * These flag bits can be combined to monitor multiple events at once. + */ +enum { + /** + * The file descriptor is available for read operations. + */ + ALOOPER_EVENT_INPUT = 1 << 0, + + /** + * The file descriptor is available for write operations. + */ + ALOOPER_EVENT_OUTPUT = 1 << 1, + + /** + * The file descriptor has encountered an error condition. + * + * The looper always sends notifications about errors; it is not necessary + * to specify this event flag in the requested event set. + */ + ALOOPER_EVENT_ERROR = 1 << 2, + + /** + * The file descriptor was hung up. + * For example, indicates that the remote end of a pipe or socket was closed. + * + * The looper always sends notifications about hangups; it is not necessary + * to specify this event flag in the requested event set. + */ + ALOOPER_EVENT_HANGUP = 1 << 3, + + /** + * The file descriptor is invalid. + * For example, the file descriptor was closed prematurely. + * + * The looper always sends notifications about invalid file descriptors; it is not necessary + * to specify this event flag in the requested event set. + */ + ALOOPER_EVENT_INVALID = 1 << 4, +}; + +/** + * For callback-based event loops, this is the prototype of the function + * that is called when a file descriptor event occurs. + * It is given the file descriptor it is associated with, + * a bitmask of the poll events that were triggered (typically ALOOPER_EVENT_INPUT), + * and the data pointer that was originally supplied. + * + * Implementations should return 1 to continue receiving callbacks, or 0 + * to have this file descriptor and callback unregistered from the looper. + */ +typedef int (*ALooper_callbackFunc)(int fd, int events, void* data); + +/** + * Waits for events to be available, with optional timeout in milliseconds. + * Invokes callbacks for all file descriptors on which an event occurred. + * + * If the timeout is zero, returns immediately without blocking. + * If the timeout is negative, waits indefinitely until an event appears. + * + * Returns ALOOPER_POLL_WAKE if the poll was awoken using wake() before + * the timeout expired and no callbacks were invoked and no other file + * descriptors were ready. + * + * Returns ALOOPER_POLL_CALLBACK if one or more callbacks were invoked. + * + * Returns ALOOPER_POLL_TIMEOUT if there was no data before the given + * timeout expired. + * + * Returns ALOOPER_POLL_ERROR if an error occurred. + * + * Returns a value >= 0 containing an identifier if its file descriptor has data + * and it has no callback function (requiring the caller here to handle it). + * In this (and only this) case outFd, outEvents and outData will contain the poll + * events and data associated with the fd, otherwise they will be set to NULL. + * + * This method does not return until it has finished invoking the appropriate callbacks + * for all file descriptors that were signalled. + */ +int ALooper_pollOnce(int timeoutMillis, int* outFd, int* outEvents, void** outData); + +/** + * Like ALooper_pollOnce(), but performs all pending callbacks until all + * data has been consumed or a file descriptor is available with no callback. + * This function will never return ALOOPER_POLL_CALLBACK. + */ +int ALooper_pollAll(int timeoutMillis, int* outFd, int* outEvents, void** outData); + +/** + * Wakes the poll asynchronously. + * + * This method can be called on any thread. + * This method returns immediately. + */ +void ALooper_wake(ALooper* looper); + +/** + * Adds a new file descriptor to be polled by the looper. + * If the same file descriptor was previously added, it is replaced. + * + * "fd" is the file descriptor to be added. + * "ident" is an identifier for this event, which is returned from ALooper_pollOnce(). + * The identifier must be >= 0, or ALOOPER_POLL_CALLBACK if providing a non-NULL callback. + * "events" are the poll events to wake up on. Typically this is ALOOPER_EVENT_INPUT. + * "callback" is the function to call when there is an event on the file descriptor. + * "data" is a private data pointer to supply to the callback. + * + * There are two main uses of this function: + * + * (1) If "callback" is non-NULL, then this function will be called when there is + * data on the file descriptor. It should execute any events it has pending, + * appropriately reading from the file descriptor. The 'ident' is ignored in this case. + * + * (2) If "callback" is NULL, the 'ident' will be returned by ALooper_pollOnce + * when its file descriptor has data available, requiring the caller to take + * care of processing it. + * + * Returns 1 if the file descriptor was added or -1 if an error occurred. + * + * This method can be called on any thread. + * This method may block briefly if it needs to wake the poll. + */ +int ALooper_addFd(ALooper* looper, int fd, int ident, int events, + ALooper_callbackFunc callback, void* data); + +/** + * Removes a previously added file descriptor from the looper. + * + * When this method returns, it is safe to close the file descriptor since the looper + * will no longer have a reference to it. However, it is possible for the callback to + * already be running or for it to run one last time if the file descriptor was already + * signalled. Calling code is responsible for ensuring that this case is safely handled. + * For example, if the callback takes care of removing itself during its own execution either + * by returning 0 or by calling this method, then it can be guaranteed to not be invoked + * again at any later time unless registered anew. + * + * Returns 1 if the file descriptor was removed, 0 if none was previously registered + * or -1 if an error occurred. + * + * This method can be called on any thread. + * This method may block briefly if it needs to wake the poll. + */ +int ALooper_removeFd(ALooper* looper, int fd); + +#ifdef __cplusplus +}; +#endif + +#endif // ANDROID_LOOPER_H |