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