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/*
* Copyright (C) 2007 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.
*/
/**
* Framework for multiplexing I/O. A selector manages a set of file
* descriptors and calls out to user-provided callback functions to read and
* write data and handle errors.
*/
#ifndef __SELECTOR_H
#define __SELECTOR_H
#ifdef __cplusplus
extern "C" {
#endif
#include <stdbool.h>
/**
* Manages SelectableFds and invokes their callbacks at appropriate times.
*/
typedef struct Selector Selector;
/**
* A selectable descriptor. Contains callbacks which the selector can invoke
* before calling select(), when the descriptor is readable or writable, and
* when the descriptor contains out-of-band data. Simply set a callback to
* NULL if you're not interested in that particular event.
*
* A selectable descriptor can indicate that it needs to be removed from the
* selector by setting the 'remove' flag. The selector will remove the
* descriptor at a later time and invoke the onRemove() callback.
*
* SelectableFd fields should only be modified from the selector loop.
*/
typedef struct SelectableFd SelectableFd;
struct SelectableFd {
/** The file descriptor itself. */
int fd;
/** Pointer to user-specific data. Can be NULL. */
void* data;
/**
* Set this flag when you no longer wish to be selected. The selector
* will invoke onRemove() when the descriptor is actually removed.
*/
bool remove;
/**
* Invoked by the selector before calling select. You can set up other
* callbacks from here as necessary.
*/
void (*beforeSelect)(SelectableFd* self);
/**
* Invoked by the selector when the descriptor has data available. Set to
* NULL to indicate that you're not interested in reading.
*/
void (*onReadable)(SelectableFd* self);
/**
* Invoked by the selector when the descriptor can accept data. Set to
* NULL to indicate that you're not interested in writing.
*/
void (*onWritable)(SelectableFd* self);
/**
* Invoked by the selector when out-of-band (OOB) data is available. Set to
* NULL to indicate that you're not interested in OOB data.
*/
void (*onExcept)(SelectableFd* self);
/**
* Invoked by the selector after the descriptor is removed from the
* selector but before the selector frees the SelectableFd memory.
*/
void (*onRemove)(SelectableFd* self);
/**
* The selector which selected this fd. Set by the selector itself.
*/
Selector* selector;
};
/**
* Creates a new selector.
*/
Selector* selectorCreate(void);
/**
* Creates a new selectable fd, adds it to the given selector and returns a
* pointer. Outside of 'selector' and 'fd', all fields are set to 0 or NULL
* by default.
*
* The selectable fd should only be modified from the selector loop thread.
*/
SelectableFd* selectorAdd(Selector* selector, int fd);
/**
* Wakes up the selector even though no I/O events occurred. Use this
* to indicate that you're ready to write to a descriptor.
*/
void selectorWakeUp(Selector* selector);
/**
* Loops continuously selecting file descriptors and firing events.
* Does not return.
*/
void selectorLoop(Selector* selector);
#ifdef __cplusplus
}
#endif
#endif /* __SELECTOR_H */
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