| 1 | /* |
| 2 | * Copyright (C) 2007 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 | /** |
| 18 | * Framework for multiplexing I/O. A selector manages a set of file |
| 19 | * descriptors and calls out to user-provided callback functions to read and |
| 20 | * write data and handle errors. |
| 21 | */ |
| 22 | |
| 23 | #ifndef __SELECTOR_H |
| 24 | #define __SELECTOR_H |
| 25 | |
| 26 | #ifdef __cplusplus |
| 27 | extern "C" { |
| 28 | #endif |
| 29 | |
| 30 | #include <stdbool.h> |
| 31 | |
| 32 | /** |
| 33 | * Manages SelectableFds and invokes their callbacks at appropriate times. |
| 34 | */ |
| 35 | typedef struct Selector Selector; |
| 36 | |
| 37 | /** |
| 38 | * A selectable descriptor. Contains callbacks which the selector can invoke |
| 39 | * before calling select(), when the descriptor is readable or writable, and |
| 40 | * when the descriptor contains out-of-band data. Simply set a callback to |
| 41 | * NULL if you're not interested in that particular event. |
| 42 | * |
| 43 | * A selectable descriptor can indicate that it needs to be removed from the |
| 44 | * selector by setting the 'remove' flag. The selector will remove the |
| 45 | * descriptor at a later time and invoke the onRemove() callback. |
| 46 | * |
| 47 | * SelectableFd fields should only be modified from the selector loop. |
| 48 | */ |
| 49 | typedef struct SelectableFd SelectableFd; |
| 50 | struct SelectableFd { |
| 51 | |
| 52 | /** The file descriptor itself. */ |
| 53 | int fd; |
| 54 | |
| 55 | /** Pointer to user-specific data. Can be NULL. */ |
| 56 | void* data; |
| 57 | |
| 58 | /** |
| 59 | * Set this flag when you no longer wish to be selected. The selector |
| 60 | * will invoke onRemove() when the descriptor is actually removed. |
| 61 | */ |
| 62 | bool remove; |
| 63 | |
| 64 | /** |
| 65 | * Invoked by the selector before calling select. You can set up other |
| 66 | * callbacks from here as necessary. |
| 67 | */ |
| 68 | void (*beforeSelect)(SelectableFd* self); |
| 69 | |
| 70 | /** |
| 71 | * Invoked by the selector when the descriptor has data available. Set to |
| 72 | * NULL to indicate that you're not interested in reading. |
| 73 | */ |
| 74 | void (*onReadable)(SelectableFd* self); |
| 75 | |
| 76 | /** |
| 77 | * Invoked by the selector when the descriptor can accept data. Set to |
| 78 | * NULL to indicate that you're not interested in writing. |
| 79 | */ |
| 80 | void (*onWritable)(SelectableFd* self); |
| 81 | |
| 82 | /** |
| 83 | * Invoked by the selector when out-of-band (OOB) data is available. Set to |
| 84 | * NULL to indicate that you're not interested in OOB data. |
| 85 | */ |
| 86 | void (*onExcept)(SelectableFd* self); |
| 87 | |
| 88 | /** |
| 89 | * Invoked by the selector after the descriptor is removed from the |
| 90 | * selector but before the selector frees the SelectableFd memory. |
| 91 | */ |
| 92 | void (*onRemove)(SelectableFd* self); |
| 93 | |
| 94 | /** |
| 95 | * The selector which selected this fd. Set by the selector itself. |
| 96 | */ |
| 97 | Selector* selector; |
| 98 | }; |
| 99 | |
| 100 | /** |
| 101 | * Creates a new selector. |
| 102 | */ |
| 103 | Selector* selectorCreate(void); |
| 104 | |
| 105 | /** |
| 106 | * Creates a new selectable fd, adds it to the given selector and returns a |
| 107 | * pointer. Outside of 'selector' and 'fd', all fields are set to 0 or NULL |
| 108 | * by default. |
| 109 | * |
| 110 | * The selectable fd should only be modified from the selector loop thread. |
| 111 | */ |
| 112 | SelectableFd* selectorAdd(Selector* selector, int fd); |
| 113 | |
| 114 | /** |
| 115 | * Wakes up the selector even though no I/O events occurred. Use this |
| 116 | * to indicate that you're ready to write to a descriptor. |
| 117 | */ |
| 118 | void selectorWakeUp(Selector* selector); |
| 119 | |
| 120 | /** |
| 121 | * Loops continuously selecting file descriptors and firing events. |
| 122 | * Does not return. |
| 123 | */ |
| 124 | void selectorLoop(Selector* selector); |
| 125 | |
| 126 | #ifdef __cplusplus |
| 127 | } |
| 128 | #endif |
| 129 | |
| 130 | #endif /* __SELECTOR_H */ |