X-Git-Url: http://mj.ucw.cz/gitweb/?a=blobdiff_plain;f=ucw%2Fmainloop.h;h=51a3683a46e145b50867c4feec9c0e82a379ca1c;hb=92b3bd34e6024ec20c67e3c1285f3a442fe6f326;hp=9ad3bed35fa91b8a1b5dc2f9ecb5114b1e7dc3f0;hpb=b453b78c24779eae3a51f9b8e6a439a834d89f96;p=libucw.git diff --git a/ucw/mainloop.h b/ucw/mainloop.h index 9ad3bed3..51a3683a 100644 --- a/ucw/mainloop.h +++ b/ucw/mainloop.h @@ -1,7 +1,7 @@ /* * UCW Library -- Main Loop * - * (c) 2004--2011 Martin Mares + * (c) 2004--2012 Martin Mares * * This software may be freely distributed and used according to the terms * of the GNU Lesser General Public License. @@ -10,7 +10,8 @@ #ifndef _UCW_MAINLOOP_H #define _UCW_MAINLOOP_H -#include "ucw/clists.h" +#include +#include #include @@ -24,10 +25,9 @@ /** The main loop context **/ struct main_context { - timestamp_t now; /** [*] Current time in milliseconds since the UNIX epoch. See @main_get_time(). **/ - ucw_time_t now_seconds; /** [*] Current time in seconds since the epoch. **/ - timestamp_t idle_time; /** [*] Total time in milliseconds spent by waiting for events. **/ - uns shutdown; /** [*] Setting this to nonzero forces the @main_loop() function to terminate. **/ + timestamp_t now; /* [*] Current time in milliseconds since an unknown epoch. See main_get_time(). */ + timestamp_t idle_time; /* [*] Total time in milliseconds spent by waiting for events. */ + uns shutdown; /* [*] Setting this to nonzero forces the main_loop() function to terminate. */ clist file_list; clist file_active_list; clist hook_list; @@ -35,6 +35,7 @@ struct main_context { clist process_list; clist signal_list; uns file_cnt; + uns single_step; #ifdef CONFIG_UCW_EPOLL int epoll_fd; /* File descriptor used for epoll */ struct epoll_event *epoll_events; @@ -89,20 +90,29 @@ void main_teardown(void); /** * Start the event loop on the current context. * It will watch the provided objects and call callbacks. - * Terminates when someone sets <> - * to nonzero, when all <> return - * <> or at last one <> - * returns <>. + * Terminates when someone calls @main_shut_down(), + * or when all <> return <> + * or at last one <> returns <>. **/ void main_loop(void); +/** + * Perform a single iteration of the main loop. + * Check if there are any events ready and process them. + * If there are none, do not wait. + **/ +void main_step(void); + /** Ask the main loop to terminate at the nearest occasion. **/ static inline void main_shut_down(void) { main_current()->shutdown = 1; } -/** Show the current state of a given context (use @main_debug() for the current context). **/ +/** + * Show the current state of a given context (use @main_debug() for the current context). + * Available only if LibUCW has been compiled with `CONFIG_UCW_DEBUG`. + **/ void main_debug_context(struct main_context *m); static inline void @@ -133,12 +143,6 @@ static inline timestamp_t main_get_now(void) return main_current()->now; } -/** An analog of @main_get_now() returning the number of seconds since the system epoch. **/ -static inline ucw_time_t main_get_now_seconds(void) -{ - return main_current()->now_seconds; -} - /** * This is a description of a timer. * You define the handler function and possibly user-defined data you wish @@ -158,7 +162,8 @@ struct main_timer { * timer. It is permitted (and usual) to call this function from the * timer's handler itself if you want the timer to trigger again. * - * The @expire parameter is absolute, use @timer_add_rel() for a relative version. + * The @expire parameter is absolute (in the same time scale as @main_get_now()), + * use @timer_add_rel() for a relative version. **/ void timer_add(struct main_timer *tm, timestamp_t expires); @@ -168,10 +173,16 @@ void timer_add_rel(struct main_timer *tm, timestamp_t expires_delta); /** * Removes a timer from the active ones. It is permitted (and common) to call * this function from the timer's handler itself if you want to deactivate - * the timer. + * the timer. Removing an already removed timer does nothing. **/ void timer_del(struct main_timer *tm); +/** Tells whether a timer is running. **/ +static inline int timer_is_active(struct main_timer *tm) +{ + return !!tm->expires; +} + /** * Forces refresh of the current timestamp cached in the active context. * You usually do not need to call this, since it is called every time the @@ -180,6 +191,79 @@ void timer_del(struct main_timer *tm); **/ void main_get_time(void); +/** Show current state of a timer. Available only if LibUCW has been compiled with `CONFIG_UCW_DEBUG`. **/ +void timer_debug(struct main_timer *tm); + +/*** + * [[hooks]] + * Loop hooks + * ---------- + * + * The hooks are called whenever the main loop performs an iteration. + * You can shutdown the main loop from within them or request an iteration + * to happen without sleeping (just poll, no waiting for events). + ***/ + +/** + * A hook. It contains the function to call and some user data. + * + * The handler() must return one value from + * <>. + * + * Fill with the hook and data and pass it to @hook_add(). + **/ +struct main_hook { + cnode n; + int (*handler)(struct main_hook *ho); /* [*] Hook function; returns HOOK_xxx */ + void *data; /* [*] For use by the handler */ +}; + +/** + * Return value of the hook handler(). + * Specifies what should happen next. + * + * - `HOOK_IDLE` -- Let the loop sleep until something happens, call after that. + * - `HOOK_RETRY` -- Force the loop to perform another iteration without sleeping. + * This will cause calling of all the hooks again soon. + * - `HOOK_DONE` -- The loop will terminate if all hooks return this. + * - `HOOK_SHUTDOWN` -- Shuts down the loop. + * + * The `HOOK_IDLE` and `HOOK_RETRY` constants are also used as return values + * of file handlers. + **/ +enum main_hook_return { + HOOK_IDLE, + HOOK_RETRY, + HOOK_DONE = -1, + HOOK_SHUTDOWN = -2 +}; + +/** + * Inserts a new hook into the loop. + * The hook will be scheduled at least once before next sleep. + * May be called from inside a hook handler too. + * Adding an already added hook is permitted and if the hook has been run, + * it will be run again before next sleep. + **/ +void hook_add(struct main_hook *ho); + +/** + * Removes an existing hook from the loop. + * May be called from inside a hook handler (to delete itself or another hook). + * Removing an already removed hook does nothing. + **/ +void hook_del(struct main_hook *ho); + +/** Tells if a hook is active (i.e., added). **/ +static inline int hook_is_active(struct main_hook *ho) +{ + return clist_is_linked(&ho->n); +} + +/** Show current state of a hook. Available only if LibUCW has been compiled with `CONFIG_UCW_DEBUG`. **/ +void hook_debug(struct main_hook *ho); + + /*** * [[file]] * Activity on file descriptors @@ -199,13 +283,15 @@ void main_get_time(void); * From within the handler functions, you are allowed to call @file_chg() and even * @file_del(). * - * The return value of a handler function should be either `HOOK_RETRY` or `HOOK_IDLE`. - * `HOOK_RETRY` signals that the function would like to consume more data immediately + * The return value of a handler function should be either <> + * or <>. <> + * signals that the function would like to consume more data immediately * (i.e., it wants to be called again soon, but the event loop can postpone it after - * processing other events to avoid starvation). `HOOK_IDLE` tells that the handler - * wants to be called when the descriptor becomes ready again. + * processing other events to avoid starvation). <> + * tells that the handler wants to be called when the descriptor becomes ready again. * - * For backward compatibility, 0 can be used instead of `HOOK_IDLE` and 1 for `HOOK_RETRY`. + * For backward compatibility, 0 can be used instead of <> + * and 1 for <>. * * If you want to read/write fixed-size blocks of data asynchronously, the * <> interface could be more convenient. @@ -237,6 +323,7 @@ struct main_file { * The file descriptor is automatically set to the non-blocking mode. **/ void file_add(struct main_file *fi); + /** * Tell the main loop that the file structure has changed. Call it whenever you * change any of the handlers. @@ -244,14 +331,25 @@ void file_add(struct main_file *fi); * Can be called only on active files (only the ones added by @file_add()). **/ void file_chg(struct main_file *fi); + /** * Removes a file from the watched set. If you want to close a descriptor, * please use this function first. * * Can be called from a handler. + * Removing an already removed file does nothing. **/ void file_del(struct main_file *fi); +/** Tells if a file is active (i.e., added). **/ +static inline int file_is_active(struct main_file *fi) +{ + return clist_is_linked(&fi->n); +} + +/** Show current state of a file. Available only if LibUCW has been compiled with `CONFIG_UCW_DEBUG`. **/ +void file_debug(struct main_file *fi); + /*** * [[blockio]] * Asynchronous block I/O @@ -262,7 +360,7 @@ void file_del(struct main_file *fi); * and writes for you. * * You just create <> and call - * @block_io_add() on it, which sets up some `main_file`s internally. + * @block_io_add() on it, which sets up some <>s internally. * Then you can just call @block_io_read() or @block_io_write() to ask for * reading or writing of a given block. When the operation is finished, * your handler function is called. @@ -272,7 +370,7 @@ void file_del(struct main_file *fi); * (except that it gets added and deleted at the right places), feel free * to adjust it from your handler functions by @block_io_set_timeout(). * When the timer expires, the error handler is automatically called with - * `MFERR_TIMEOUT`. + * <>. ***/ /** The block I/O structure. **/ @@ -292,20 +390,20 @@ struct main_block_io { /** Activate a block I/O structure. **/ void block_io_add(struct main_block_io *bio, int fd); -/** Deactivate a block I/O structure. **/ +/** Deactivate a block I/O structure. Calling twice is safe. **/ void block_io_del(struct main_block_io *bio); /** * Specifies when or why an error happened. This is passed to the error handler. * `errno` is still set to the original source of error. The only exception - * is `MFERR_TIMEOUT`, in which case `errno` is not set and the only possible + * is `BIO_ERR_TIMEOUT`, in which case `errno` is not set and the only possible * cause of it is timeout of the timer associated with the block_io * (see @block_io_set_timeout()). **/ enum block_io_err_cause { - MFERR_READ, - MFERR_WRITE, - MFERR_TIMEOUT + BIO_ERR_READ, + BIO_ERR_WRITE, + BIO_ERR_TIMEOUT }; /** @@ -338,7 +436,7 @@ void block_io_write(struct main_block_io *bio, void *buf, uns len); /** * Sets a timer for a file @bio. If the timer is not overwritten or disabled * until @expires_delta milliseconds, the file timeouts and error_handler() is called with - * <>. A value of `0` stops the timer. + * <>. A value of `0` stops the timer. * * Previous setting of the timeout on the same file will be overwritten. * @@ -351,58 +449,128 @@ void block_io_write(struct main_block_io *bio, void *buf, uns len); **/ void block_io_set_timeout(struct main_block_io *bio, timestamp_t expires_delta); +/** Tells if a @bio is active (i.e., added). **/ +static inline int block_io_is_active(struct main_block_io *bio) +{ + return file_is_active(&bio->file); +} + /*** - * [[hooks]] - * Loop hooks - * ---------- + * [[recordio]] + * Asynchronous record I/O + * ----------------------- + * + * Record-based I/O is another front-end to the main loop file operations. + * Unlike its older cousin `main_block_io`, it is able to process records + * of variable length. + * + * To set it up, you create <> and call + * @rec_io_add() on it, which sets up some <>s internally. + * + * To read data from the file, call @rec_io_start_read() first. Whenever any data + * arrive from the file, they are appended to an internal buffer and the `read_handler` + * hook is called. The hook checks if the buffer already contains a complete record. + * If it is so, it processes the record and returns the number of bytes consumed. + * Otherwise, it returns 0 to tell the buffering machinery that more data are needed. + * When the read handler decides to destroy the `main_rec_io`, it must return `~0U`. + * + * On the write side, `main_rec_io` maintains a buffer keeping all data that should + * be written to the file. The @rec_io_write() function appends data to this buffer + * and it is written on background. A simple flow-control mechanism can be asked + * for: when more than `write_throttle_read` data are buffered for writing, reading + * is temporarily suspended. + * + * Additionally, the record I/O is equipped with a timer, which can be used + * to detect communication timeouts. The timer is not touched internally + * (except that it gets added and deleted at the right places), feel free + * to adjust it from your handler functions by @rec_io_set_timeout(). * - * The hooks are called whenever the main loop performs an iteration. - * You can shutdown the main loop from within them or request an iteration - * to happen without sleeping (just poll, no waiting for events). + * All important events are passed to the `notify_handler`: errors when + * reading or writing, timeouts, the write buffer becoming empty, ... See + * <> for a complete list. ***/ -/** - * A hook. It contains the function to call and some user data. - * - * The handler() must return one value from - * <>. - * - * Fill with the hook and data and pass it to @hook_add(). - **/ -struct main_hook { - cnode n; - int (*handler)(struct main_hook *ho); /* [*] Hook function; returns HOOK_xxx */ - void *data; /* [*] For use by the handler */ +/** The record I/O structure. **/ +struct main_rec_io { + struct main_file file; + byte *read_buf; + byte *read_rec_start; /* [*] Start of current record */ + uns read_avail; /* [*] How much data is available */ + uns read_prev_avail; /* [*] How much data was available in previous read_handler */ + uns read_buf_size; /* [*] Read buffer size allocated (can be set before rec_io_add()) */ + uns read_started; /* Reading requested by user */ + uns read_running; /* Reading really runs (read_started && not stopped by write_throttle_read) */ + uns read_rec_max; /* [*] Maximum record size (0=unlimited) */ + clist busy_write_buffers; + clist idle_write_buffers; + uns write_buf_size; /* [*] Write buffer size allocated (can be set before rec_io_add()) */ + uns write_watermark; /* [*] How much data are waiting to be written */ + uns write_throttle_read; /* [*] If more than write_throttle_read bytes are buffered, stop reading; 0=no stopping */ + uns (*read_handler)(struct main_rec_io *rio); /* [*] Called whenever more bytes are read; returns 0 (want more) or number of bytes eaten */ + int (*notify_handler)(struct main_rec_io *rio, int status); /* [*] Called to notify about errors and other events */ + /* Returns either HOOK_RETRY or HOOK_IDLE. */ + struct main_timer timer; + struct main_hook start_read_hook; /* Used internally to defer rec_io_start_read() */ + void *data; /* [*] Data for use by the handlers */ }; +/** Activate a record I/O structure. **/ +void rec_io_add(struct main_rec_io *rio, int fd); + +/** Deactivate a record I/O structure. Calling twice is safe. **/ +void rec_io_del(struct main_rec_io *rio); + /** - * Return value of the hook handler(). - * Specifies what should happen next. + * Start reading. * - * - `HOOK_IDLE` -- Let the loop sleep until something happens, call after that. - * - `HOOK_RETRY` -- Force the loop to perform another iteration without sleeping. - * This will cause calling of all the hooks again soon. - * - `HOOK_DONE` -- The loop will terminate if all hooks return this. - * - `HOOK_SHUTDOWN` -- Shuts down the loop. - **/ -enum main_hook_return { - HOOK_IDLE, - HOOK_RETRY, - HOOK_DONE = -1, - HOOK_SHUTDOWN = -2 -}; + * When there were some data in the buffer (e.g., because @rec_io_stop_read() + * was called from the `read_handler`), it is processed as if it were read + * from the file once again. That is, `read_prev_avail` is reset to 0 and + * the `read_handler` is called to process all buffered data. + ***/ +void rec_io_start_read(struct main_rec_io *rio); + +/** Stop reading. **/ +void rec_io_stop_read(struct main_rec_io *rio); + +/** Analogous to @block_io_set_timeout(). **/ +void rec_io_set_timeout(struct main_rec_io *bio, timestamp_t expires_delta); + +void rec_io_write(struct main_rec_io *rio, void *data, uns len); /** - * Inserts a new hook into the loop. - * The hook will be scheduled at least once before next sleep. - * May be called from inside a hook handler too. + * An auxiliary function used for parsing of lines. When called in the @read_handler, + * it searches for the end of line character. When a complete line is found, the length + * of the line (including the end of line character) is returned. Otherwise, it returns zero. **/ -void hook_add(struct main_hook *ho); +uns rec_io_parse_line(struct main_rec_io *rio); + /** - * Removes an existing hook from the loop. - * May be called from inside a hook handler (to delete itself or other hook). + * Specifies what kind of error or other event happened, when the @notify_handler + * is called. In case of I/O errors, `errno` is still set. + * + * Upon @RIO_ERR_READ, @RIO_ERR_RECORD_TOO_LARGE and @RIO_EVENT_EOF, reading is stopped + * automatically. Upon @RIO_ERR_WRITE, writing is stopped. Upon @RIO_ERR_TIMEOUT, only the + * timer is deactivated. + * + * In all cases, the notification handler is allowed to call @rec_io_del(), but it + * must return @HOOK_IDLE in such cases. **/ -void hook_del(struct main_hook *ho); +enum rec_io_notify_status { + RIO_ERR_READ = -1, /* read() returned an error, errno set */ + RIO_ERR_WRITE = -2, /* write() returned an error, errno set */ + RIO_ERR_TIMEOUT = -3, /* A timeout has occurred */ + RIO_ERR_RECORD_TOO_LARGE = -4, /* Read: read_rec_max has been exceeded */ + RIO_EVENT_ALL_WRITTEN = 1, /* All buffered data has been written */ + RIO_EVENT_PART_WRITTEN = 2, /* Some buffered data has been written, but more remains */ + RIO_EVENT_EOF = 3, /* Read: EOF seen */ +}; + +/** Tells if a @rio is active (i.e., added). **/ +static inline int rec_io_is_active(struct main_rec_io *rio) +{ + return file_is_active(&rio->file); +} /*** * [[process]] @@ -433,12 +601,15 @@ struct main_process { * if you removed the process previously by @process_del(). **/ void process_add(struct main_process *mp); + /** * Removes the process from the watched set. This is done * automatically, when the process terminates, so you need it only * when you do not want to watch a running process any more. + * Removing an already removed process does nothing. */ void process_del(struct main_process *mp); + /** * Forks and fills the @mp with information about the new process. * @@ -455,16 +626,62 @@ void process_del(struct main_process *mp); **/ int process_fork(struct main_process *mp); -/* FIXME: Docs */ +/** Tells if a process is active (i.e., added). **/ +static inline int process_is_active(struct main_process *mp) +{ + return clist_is_linked(&mp->n); +} + +/** Show current state of a process. Available only if LibUCW has been compiled with `CONFIG_UCW_DEBUG`. **/ +void process_debug(struct main_process *pr); +/*** + * [[signal]] + * Synchronous delivery of signals + * ------------------------------- + * + * UNIX signals are delivered to processes in an asynchronous way: when a signal + * arrives (and it is not blocked), the process is interrupted and the corresponding + * signal handler function is called. However, most data structures and even most + * system library calls are not safe with respect to interrupts, so most program + * using signals contain subtle race conditions and may fail once in a long while. + * + * To avoid this problem, the event loop can be asked for synchronous delivery + * of signals. When a signal registered with @signal_add() arrives, it wakes up + * the loop (if it is not already awake) and it is processed in the same way + * as all other events. + * + * When used in a multi-threaded program, the signals are delivered to the thread + * which is currently using the particular main loop context. If the context is not + * current in any thread, the signals are blocked. + * + * As usually with UNIX signals, multiple instances of a single signal can be + * merged and delivered only once. (Some implementations of the main loop can even + * drop a signal completely during very intensive signal traffic, when an internal + * signal queue overflows.) + ***/ + +/** Description of a signal to catch. **/ struct main_signal { cnode n; - int signum; - void (*handler)(struct main_signal *ms); - void *data; + int signum; /* [*] Signal to catch */ + void (*handler)(struct main_signal *ms); /* [*] Called when the signal arrives */ + void *data; /* [*] For use by the handler */ }; +/** Request a signal to be caught and delivered synchronously. **/ void signal_add(struct main_signal *ms); + +/** Cancel a request for signal catching. Calling twice is safe. **/ void signal_del(struct main_signal *ms); +/** Tells if a signal catcher is active (i.e., added). **/ +static inline int signal_is_active(struct main_signal *ms) +{ + return clist_is_linked(&ms->n); +} + +/** Show current state of a signal catcher. Available only if LibUCW has been compiled with `CONFIG_UCW_DEBUG`. **/ +void signal_debug(struct main_signal *sg); + #endif