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#ifndef IRC_QUEUE_H

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#define IRC_QUEUE_H

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/**

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 * @file

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 *

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 * Ratelimited queue of outgoing irc_line's for use with irc_conn.

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 *

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 * This implements the basic flood control algorithm as described in RFC1459 section 8.10.

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 */

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#include "irc_line.h"

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#include <sys/queue.h>

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#include <event2/event.h>

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/**

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 * Number of seconds of penalty applied for each message

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 */

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#define IRC_QUEUE_PENALTY 2

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/**

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 * Maximum allowed burst, in seconds

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 */

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#define IRC_QUEUE_WINDOW 10

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/**

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 * An enqueued irc_line for later delivery

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 */

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struct irc_queue_entry {

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    /** The formatted irc_line data, including terminating CRLF */

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    char line_buf[IRC_LINE_MAX + 2];

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    /** Our entry in the irc_queue list */

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    TAILQ_ENTRY(irc_queue_entry) queue_list;

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};

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/**

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 * The queue state and timing algorithm, as described in the RFC:

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 *  * A line will be sent directly if the current timer is less than IRC_QUEUE_WINDOW seconds into the future, and

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 *    IRC_QUEUE_PENALTY seconds are added on to the timer.

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 *  * Otherwise, the line is stored as a irc_queue_entry and enqueued for later transmission, once the timer value

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 *    drops below IRC_QUEUE_WINDOW seconds into the future.

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 *  * The above is repeated for each dequeued line.

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 *

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 * Additionally, if sending a line fails due to the line_proto socket buffer being full, this also handles this case

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 * by queueing the line for later sending.

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 *

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 * Note that the timing behaviour of this is rather unexact - the socket layer may introduce its own delays/jitter which

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 * we can't measure or control here, but at least we make an effort. This should work OK as long as the outgoing lines

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 * don't accumulate in the socket's write buffer too much. XXX: maybe tweak socket params to try and "disable" 

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 * buffering on our end to improve accuracy?

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 */

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struct irc_queue {

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    /** The line_proto that we can send the messages out on */

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    struct line_proto *lp;

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    /** Our timeout used for delaying messages */

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    struct event *ev;

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    /** Current "message timer" value, may be up to IRC_QUEUE_WINDOW seconds in the future */

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    time_t timer;

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    /** The actual queue of messages */

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    TAILQ_HEAD(irc_queue_entry_list, irc_queue_entry) list;

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};

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/**

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 * Create a new irc_queue for use with the given line_proto

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 */

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err_t irc_queue_create (struct irc_queue **queue_ptr, struct event_base *ev_base, struct line_proto *lp, error_t *err);

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/**

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 * Process a line, either sending it directly, or enqueueing it, based on the timer state.

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 */

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err_t irc_queue_process (struct irc_queue *queue, const struct irc_line *line);

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/**

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 * Destroy the irc_queue, releasing all queued lines

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 */

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void irc_queue_destroy (struct irc_queue *queue);

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#endif /* IRC_QUEUE_H */