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Annotation of embedaddon/strongswan/src/libstrongswan/processing/watcher.h, revision 1.1

1.1     ! misho       1: /*
        !             2:  * Copyright (C) 2013 Martin Willi
        !             3:  * Copyright (C) 2013 revosec AG
        !             4:  *
        !             5:  * This program is free software; you can redistribute it and/or modify it
        !             6:  * under the terms of the GNU General Public License as published by the
        !             7:  * Free Software Foundation; either version 2 of the License, or (at your
        !             8:  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
        !             9:  *
        !            10:  * This program is distributed in the hope that it will be useful, but
        !            11:  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
        !            12:  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
        !            13:  * for more details.
        !            14:  */
        !            15: 
        !            16: /**
        !            17:  * @defgroup watcher watcher
        !            18:  * @{ @ingroup processor
        !            19:  */
        !            20: 
        !            21: #ifndef WATCHER_H_
        !            22: #define WATCHER_H_
        !            23: 
        !            24: typedef struct watcher_t watcher_t;
        !            25: typedef enum watcher_event_t watcher_event_t;
        !            26: typedef enum watcher_state_t watcher_state_t;
        !            27: 
        !            28: #include <library.h>
        !            29: 
        !            30: /**
        !            31:  * Callback function to register for file descriptor events.
        !            32:  *
        !            33:  * The callback is executed asynchronously using a thread from the pool.
        !            34:  * Monitoring of fd is temporarily suspended to avoid additional events while
        !            35:  * it is processed asynchronously. To allow concurrent events, one can quickly
        !            36:  * process it (using a read/write) and return from the callback. This will
        !            37:  * re-enable the event, while the data read can be processed in another
        !            38:  * asynchronous job.
        !            39:  *
        !            40:  * On Linux, even if select() marks an FD as "ready", a subsequent read/write
        !            41:  * can block. It is therefore highly recommended to use non-blocking I/O
        !            42:  * and handle EAGAIN/EWOULDBLOCK gracefully.
        !            43:  *
        !            44:  * @param data         user data passed during registration
        !            45:  * @param fd           file descriptor the event occurred on
        !            46:  * @param event                type of event
        !            47:  * @return                     TRUE to keep watching event, FALSE to unregister fd for event
        !            48:  */
        !            49: typedef bool (*watcher_cb_t)(void *data, int fd, watcher_event_t event);
        !            50: 
        !            51: /**
        !            52:  * What events to watch for a file descriptor.
        !            53:  */
        !            54: enum watcher_event_t {
        !            55:        WATCHER_READ = (1<<0),
        !            56:        WATCHER_WRITE = (1<<1),
        !            57:        WATCHER_EXCEPT = (1<<2),
        !            58: };
        !            59: 
        !            60: /**
        !            61:  * State the watcher currently is in
        !            62:  */
        !            63: enum watcher_state_t {
        !            64:        /** no watcher thread running or queued */
        !            65:        WATCHER_STOPPED = 0,
        !            66:        /** a job has been queued for watching, but not yet started */
        !            67:        WATCHER_QUEUED,
        !            68:        /** a watcher thread is active, dispatching socket events */
        !            69:        WATCHER_RUNNING,
        !            70: };
        !            71: 
        !            72: /**
        !            73:  * Watch multiple file descriptors using select().
        !            74:  */
        !            75: struct watcher_t {
        !            76: 
        !            77:        /**
        !            78:         * Start watching a new file descriptor.
        !            79:         *
        !            80:         * Multiple callbacks can be registered for the same file descriptor, and
        !            81:         * all of them get notified. Such callbacks are executed concurrently.
        !            82:         *
        !            83:         * @param fd            file descriptor to start watching
        !            84:         * @param events        ORed set of events to watch
        !            85:         * @param cb            callback function to invoke on events
        !            86:         * @param data          data to pass to cb()
        !            87:         */
        !            88:        void (*add)(watcher_t *this, int fd, watcher_event_t events,
        !            89:                                watcher_cb_t cb, void *data);
        !            90: 
        !            91:        /**
        !            92:         * Stop watching a previously registered file descriptor.
        !            93:         *
        !            94:         * This call blocks until any active callback for this FD returns. All
        !            95:         * callbacks registered for that FD get unregistered.
        !            96:         *
        !            97:         * @param fd            file descriptor to stop watching
        !            98:         */
        !            99:        void (*remove)(watcher_t *this, int fd);
        !           100: 
        !           101:        /**
        !           102:         * Get the current watcher state
        !           103:         *
        !           104:         * @return                      currently active watcher state
        !           105:         */
        !           106:        watcher_state_t (*get_state)(watcher_t *this);
        !           107: 
        !           108:        /**
        !           109:         * Destroy a watcher_t.
        !           110:         */
        !           111:        void (*destroy)(watcher_t *this);
        !           112: };
        !           113: 
        !           114: /**
        !           115:  * Create a watcher instance.
        !           116:  *
        !           117:  * @return             watcher
        !           118:  */
        !           119: watcher_t *watcher_create();
        !           120: 
        !           121: #endif /** WATCHER_H_ @}*/