/*
* This file is part of DisOrder.
- * Copyright (C) 2004, 2005 Richard Kettlewell
+ * Copyright (C) 2004, 2005, 2007 Richard Kettlewell
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
*/
+/** @file lib/event.c
+ * @brief DisOrder event loop
+ */
#include <config.h>
#include <sys/types.h>
#include <sys/resource.h>
#include <sys/wait.h>
+#include <sys/stat.h>
#include <unistd.h>
#include <assert.h>
#include <signal.h>
#include "syscalls.h"
#include "printf.h"
#include "sink.h"
+#include "vector.h"
+/** @brief A timeout */
struct timeout {
struct timeout *next;
struct timeval when;
int resolve;
};
+/** @brief A file descriptor in one mode */
struct fd {
int fd;
ev_fd_callback *callback;
void *u;
+ const char *what;
};
+/** @brief All the file descriptors in a given mode */
struct fdmode {
+ /** @brief Mask of active file descriptors passed to @c select() */
fd_set enabled;
+
+ /** @brief File descriptor mask returned from @c select() */
fd_set tripped;
- int nfds, fdslots;
+
+ /** @brief Number of file descriptors in @p fds */
+ int nfds;
+
+ /** @brief Number of slots in @p fds */
+ int fdslots;
+
+ /** @brief Array of all active file descriptors */
struct fd *fds;
+
+ /** @brief Highest-numbered file descriptor or 0 */
int maxfd;
};
+/** @brief A signal handler */
struct signal {
struct sigaction oldsa;
ev_signal_callback *callback;
void *u;
};
+/** @brief A child process */
struct child {
pid_t pid;
int options;
void *u;
};
+/** @brief An event loop */
struct ev_source {
+ /** @brief File descriptors, per mode */
struct fdmode mode[ev_nmodes];
+
+ /** @brief Sorted linked list of timeouts
+ *
+ * We could use @ref HEAP_TYPE now, but there aren't many timeouts.
+ */
struct timeout *timeouts;
+
+ /** @brief Array of handled signals */
struct signal signals[NSIG];
+
+ /** @brief Mask of handled signals */
sigset_t sigmask;
+
+ /** @brief Escape early from handling of @c select() results
+ *
+ * This is set if any of the file descriptor arrays are invalidated, since
+ * it's then not safe for processing of them to continue.
+ */
int escape;
+
+ /** @brief Signal handling pipe
+ *
+ * The signal handle writes signal numbers down this pipe.
+ */
int sigpipe[2];
- int nchildren, nchildslots;
+
+ /** @brief Number of child processes in @p children */
+ int nchildren;
+
+ /** @brief Number of slots in @p children */
+ int nchildslots;
+
+ /** @brief Array of child processes */
struct child *children;
};
+/** @brief Names of file descriptor modes */
static const char *modenames[] = { "read", "write", "except" };
/* utilities ******************************************************************/
+/** @brief Great-than comparison for timevals
+ *
+ * Ought to be in @file lib/timeval.h
+ */
static inline int gt(const struct timeval *a, const struct timeval *b) {
if(a->tv_sec > b->tv_sec)
return 1;
return 0;
}
+/** @brief Greater-than-or-equal comparison for timevals
+ *
+ * Ought to be in @ref lib/timeval.h
+ */
static inline int ge(const struct timeval *a, const struct timeval *b) {
return !gt(b, a);
}
/* creation *******************************************************************/
+/** @brief Create a new event loop */
ev_source *ev_new(void) {
ev_source *ev = xmalloc(sizeof *ev);
int n;
/* event loop *****************************************************************/
+/** @brief Run the event loop
+ * @return -1 on error, non-0 if any callback returned non-0
+ */
int ev_run(ev_source *ev) {
for(;;) {
struct timeval now;
int ret;
int maxfd;
struct timeout *t, **tt;
+ struct stat sb;
xgettimeofday(&now, 0);
/* Handle timeouts. We don't want to handle any timeouts that are added
xsigprocmask(SIG_BLOCK, &ev->sigmask, 0);
if(n < 0) {
error(errno, "error calling select");
+ if(errno == EBADF) {
+ /* If there's a bad FD in the mix then check them all and log what we
+ * find, to ease debugging */
+ for(mode = 0; mode < ev_nmodes; ++mode) {
+ for(n = 0; n < ev->mode[mode].nfds; ++n) {
+ const int fd = ev->mode[mode].fds[n].fd;
+
+ if(FD_ISSET(fd, &ev->mode[mode].enabled)
+ && fstat(fd, &sb) < 0)
+ error(errno, "mode %s fstat %d (%s)",
+ modenames[mode], fd, ev->mode[mode].fds[n].what);
+ }
+ for(n = 0; n <= maxfd; ++n)
+ if(FD_ISSET(n, &ev->mode[mode].enabled)
+ && fstat(n, &sb) < 0)
+ error(errno, "mode %s fstat %d", modenames[mode], n);
+ }
+ }
return -1;
}
if(n > 0) {
/* file descriptors ***********************************************************/
+/** @brief Register a file descriptor
+ * @param ev Event loop
+ * @param mode @c ev_read or @c ev_write
+ * @param fd File descriptor
+ * @param callback Called when @p is readable/writable
+ * @param u Passed to @p callback
+ * @param what Text description
+ * @return 0 on success, non-0 on error
+ *
+ * Sets @ref ev_source::escape, so no further processing of file descriptors
+ * will occur this time round the event loop.
+ */
int ev_fd(ev_source *ev,
ev_fdmode mode,
int fd,
ev_fd_callback *callback,
- void *u) {
+ void *u,
+ const char *what) {
int n;
D(("registering %s fd %d callback %p %p", modenames[mode], fd,
ev->mode[mode].fds[n].fd = fd;
ev->mode[mode].fds[n].callback = callback;
ev->mode[mode].fds[n].u = u;
+ ev->mode[mode].fds[n].what = what;
if(fd > ev->mode[mode].maxfd)
ev->mode[mode].maxfd = fd;
ev->escape = 1;
return 0;
}
+/** @brief Cancel a file descriptor
+ * @param ev Event loop
+ * @param mode @c ev_read or @c ev_write
+ * @param fd File descriptor
+ * @return 0 on success, non-0 on error
+ *
+ * Sets @ref ev_source::escape, so no further processing of file descriptors
+ * will occur this time round the event loop.
+ */
int ev_fd_cancel(ev_source *ev, ev_fdmode mode, int fd) {
int n;
int maxfd;
return 0;
}
+/** @brief Re-enable a file descriptor
+ * @param ev Event loop
+ * @param mode @c ev_read or @c ev_write
+ * @param fd File descriptor
+ * @return 0 on success, non-0 on error
+ *
+ * It is harmless if @p fd is currently disabled, but it must not have been
+ * cancelled.
+ */
int ev_fd_enable(ev_source *ev, ev_fdmode mode, int fd) {
+ assert(fd >= 0);
D(("enabling mode %s fd %d", modenames[mode], fd));
FD_SET(fd, &ev->mode[mode].enabled);
return 0;
}
+/** @brief Temporarily disable a file descriptor
+ * @param ev Event loop
+ * @param mode @c ev_read or @c ev_write
+ * @param fd File descriptor
+ * @return 0 on success, non-0 on error
+ *
+ * Re-enable with ev_fd_enable(). It is harmless if @p fd is already disabled,
+ * but it must not have been cancelled.
+ */
int ev_fd_disable(ev_source *ev, ev_fdmode mode, int fd) {
D(("disabling mode %s fd %d", modenames[mode], fd));
FD_CLR(fd, &ev->mode[mode].enabled);
FD_CLR(fd, &ev->mode[mode].tripped);
+ /* Suppress any pending callbacks */
+ ev->escape = 1;
return 0;
}
+/** @brief Log a report of file descriptor state */
+void ev_report(ev_source *ev) {
+ int n, fd;
+ ev_fdmode mode;
+ struct dynstr d[1];
+ char b[4096];
+
+ if(!debugging)
+ return;
+ dynstr_init(d);
+ for(mode = 0; mode < ev_nmodes; ++mode) {
+ D(("mode %s maxfd %d", modenames[mode], ev->mode[mode].maxfd));
+ for(n = 0; n < ev->mode[mode].nfds; ++n) {
+ fd = ev->mode[mode].fds[n].fd;
+ D(("fd %s %d%s%s (%s)", modenames[mode], fd,
+ FD_ISSET(fd, &ev->mode[mode].enabled) ? " enabled" : "",
+ FD_ISSET(fd, &ev->mode[mode].tripped) ? " tripped" : "",
+ ev->mode[mode].fds[n].what));
+ }
+ d->nvec = 0;
+ for(fd = 0; fd <= ev->mode[mode].maxfd; ++fd) {
+ if(!FD_ISSET(fd, &ev->mode[mode].enabled))
+ continue;
+ for(n = 0; n < ev->mode[mode].nfds; ++n) {
+ if(ev->mode[mode].fds[n].fd == fd)
+ break;
+ }
+ if(n < ev->mode[mode].nfds)
+ snprintf(b, sizeof b, "%d(%s)", fd, ev->mode[mode].fds[n].what);
+ else
+ snprintf(b, sizeof b, "%d", fd);
+ dynstr_append(d, ' ');
+ dynstr_append_string(d, b);
+ }
+ dynstr_terminate(d);
+ D(("%s enabled:%s", modenames[mode], d->vec));
+ }
+}
+
/* timeouts *******************************************************************/
+/** @brief Register a timeout
+ * @param ev Event source
+ * @param handlep Where to store timeout handle, or @c NULL
+ * @param when Earliest time to call @p callback, or @c NULL
+ * @param callback Function to call at or after @p when
+ * @param u Passed to @p callback
+ * @return 0 on success, non-0 on error
+ *
+ * If @p when is a null pointer then a time of 0 is assumed. The effect is to
+ * call the timeout handler from ev_run() next time around the event loop.
+ * This is used internally to schedule various operations if it is not
+ * convenient to call them from the current place in the call stack, or
+ * externally to ensure that other clients of the event loop get a look in when
+ * performing some lengthy operation.
+ */
int ev_timeout(ev_source *ev,
ev_timeout_handle *handlep,
const struct timeval *when,
return 0;
}
+/** @brief Cancel a timeout
+ * @param ev Event loop
+ * @param handle Handle returned from ev_timeout(), or 0
+ * @return 0 on success, non-0 on error
+ *
+ * If @p handle is 0 then this is a no-op.
+ */
int ev_timeout_cancel(ev_source *ev,
ev_timeout_handle handle) {
struct timeout *t = handle, *p, **pp;
+ if(!t)
+ return 0;
for(pp = &ev->timeouts; (p = *pp) && p != t; pp = &p->next)
;
if(p) {
/* signals ********************************************************************/
+/** @brief Mapping of signals to pipe write ends
+ *
+ * The pipes are per-event loop, it's possible in theory for there to be
+ * multiple event loops (e.g. in different threads), although in fact DisOrder
+ * does not do this.
+ */
static int sigfd[NSIG];
+/** @brief The signal handler
+ * @param s Signal number
+ *
+ * Writes to @c sigfd[s].
+ */
static void sighandler(int s) {
unsigned char sc = s;
static const char errmsg[] = "error writing to signal pipe";
}
}
+/** @brief Read callback for signals */
static int signal_read(ev_source *ev,
int attribute((unused)) fd,
void attribute((unused)) *u) {
return 0;
}
+/** @brief Close the signal pipe */
static void close_sigpipe(ev_source *ev) {
int save_errno = errno;
errno = save_errno;
}
+/** @brief Register a signal handler
+ * @param ev Event loop
+ * @param sig Signal to handle
+ * @param callback Called when signal is delivered
+ * @param u Passed to @p callback
+ * @return 0 on success, non-0 on error
+ *
+ * Note that @p callback is called from inside ev_run(), not from inside the
+ * signal handler, so the usual restrictions on signal handlers do not apply.
+ */
int ev_signal(ev_source *ev,
int sig,
ev_signal_callback *callback,
nonblock(ev->sigpipe[n]);
cloexec(ev->sigpipe[n]);
}
- if(ev_fd(ev, ev_read, ev->sigpipe[0], signal_read, 0)) {
+ if(ev_fd(ev, ev_read, ev->sigpipe[0], signal_read, 0, "sigpipe read")) {
close_sigpipe(ev);
return -1;
}
return 0;
}
+/** @brief Cancel a signal handler
+ * @param ev Event loop
+ * @param sig Signal to cancel
+ * @return 0 on success, non-0 on error
+ */
int ev_signal_cancel(ev_source *ev,
int sig) {
sigset_t ss;
return 0;
}
+/** @brief Clean up signal handling
+ * @param ev Event loop
+ *
+ * This function can be called from inside a fork. It restores signal
+ * handlers, unblocks the signals, and closes the signal pipe for @p ev.
+ */
void ev_signal_atfork(ev_source *ev) {
int sig;
/* child processes ************************************************************/
+/** @brief Called on SIGCHLD */
static int sigchld_callback(ev_source *ev,
int attribute((unused)) sig,
void attribute((unused)) *u) {
return 0;
}
+/** @brief Configure event loop for child process handling
+ * @return 0 on success, non-0 on error
+ *
+ * Currently at most one event loop can handle child processes and it must be
+ * distinguished from others by calling this function on it. This could be
+ * fixed but since no process ever makes use of more than one event loop there
+ * is no need.
+ */
int ev_child_setup(ev_source *ev) {
D(("installing SIGCHLD handler"));
return ev_signal(ev, SIGCHLD, sigchld_callback, 0);
}
+/** @brief Wait for a child process to terminate
+ * @param ev Event loop
+ * @param pid Process ID of child
+ * @param options Options to pass to @c wait4()
+ * @param callback Called when child terminates (or possibly when it stops)
+ * @param u Passed to @p callback
+ * @return 0 on success, non-0 on error
+ *
+ * You must have called ev_child_setup() on @p ev once first.
+ */
int ev_child(ev_source *ev,
pid_t pid,
int options,
return 0;
}
+/** @brief Stop waiting for a child process
+ * @param ev Event loop
+ * @param pid Child process ID
+ * @return 0 on success, non-0 on error
+ */
int ev_child_cancel(ev_source *ev,
pid_t pid) {
int n;
/* socket listeners ***********************************************************/
+/** @brief State for a socket listener */
struct listen_state {
ev_listen_callback *callback;
void *u;
};
+/** @brief Called when a listenign socket is readable */
static int listen_callback(ev_source *ev, int fd, void *u) {
const struct listen_state *l = u;
int newfd;
return 0;
}
+/** @brief Listen on a socket for inbound stream connections
+ * @param ev Event source
+ * @param fd File descriptor of socket
+ * @param callback Called when a new connection arrives
+ * @param u Passed to @p callback
+ * @param what Text description of socket
+ * @return 0 on success, non-0 on error
+ */
int ev_listen(ev_source *ev,
int fd,
ev_listen_callback *callback,
- void *u) {
+ void *u,
+ const char *what) {
struct listen_state *l = xmalloc(sizeof *l);
D(("registering listener fd %d callback %p %p", fd, (void *)callback, u));
l->callback = callback;
l->u = u;
- return ev_fd(ev, ev_read, fd, listen_callback, l);
+ return ev_fd(ev, ev_read, fd, listen_callback, l, what);
}
+/** @brief Stop listening on a socket
+ * @param ev Event loop
+ * @param fd File descriptor of socket
+ * @return 0 on success, non-0 on error
+ */
int ev_listen_cancel(ev_source *ev, int fd) {
D(("cancelling listener fd %d", fd));
return ev_fd_cancel(ev, ev_read, fd);
/* buffer *********************************************************************/
+/** @brief Buffer structure */
struct buffer {
char *base, *start, *end, *top;
};
-/* make sure there is @bytes@ available at @b->end@ */
+/* @brief Make sure there is @p bytes available at @c b->end */
static void buffer_space(struct buffer *b, size_t bytes) {
D(("buffer_space %p %p %p %p want %lu",
(void *)b->base, (void *)b->start, (void *)b->end, (void *)b->top,
(void *)b->base, (void *)b->start, (void *)b->end, (void *)b->top));
}
-/* buffered writer ************************************************************/
+/* readers and writers *******************************************************/
+/** @brief State structure for a buffered writer */
struct ev_writer {
+ /** @brief Sink used for writing to the buffer */
struct sink s;
+
+ /** @brief Output buffer */
struct buffer b;
+
+ /** @brief File descriptor to write to */
int fd;
+
+ /** @brief Set if there'll be no more output */
int eof;
+
+ /** @brief Error/termination callback */
ev_error_callback *callback;
+
+ /** @brief Passed to @p callback */
+ void *u;
+
+ /** @brief Parent event source */
+ ev_source *ev;
+
+ /** @brief Maximum amount of time between succesful writes, 0 = don't care */
+ int timebound;
+ /** @brief Maximum amount of data to buffer, 0 = don't care */
+ int spacebound;
+ /** @brief Error code to pass to @p callback (see writer_shutdown()) */
+ int error;
+ /** @brief Timeout handle for @p timebound (or 0) */
+ ev_timeout_handle timeout;
+
+ /** @brief Description of this writer */
+ const char *what;
+
+ /** @brief Tied reader or 0 */
+ ev_reader *reader;
+};
+
+/** @brief State structure for a buffered reader */
+struct ev_reader {
+ /** @brief Input buffer */
+ struct buffer b;
+ /** @brief File descriptor read from */
+ int fd;
+ /** @brief Called when new data is available */
+ ev_reader_callback *callback;
+ /** @brief Called on error and shutdown */
+ ev_error_callback *error_callback;
+ /** @brief Passed to @p callback and @p error_callback */
void *u;
+ /** @brief Parent event loop */
ev_source *ev;
+ /** @brief Set when EOF is detected */
+ int eof;
+ /** @brief Error code to pass to error callback */
+ int error;
+ /** @brief Tied writer or NULL */
+ ev_writer *writer;
};
-static int writer_callback(ev_source *ev, int fd, void *u) {
+/* buffered writer ************************************************************/
+
+/** @brief Shut down the writer
+ *
+ * This is called to shut down a writer. The error callback is not called
+ * through any other path. Also we do not cancel @p fd from anywhere else,
+ * though we might disable it.
+ *
+ * It has the signature of a timeout callback so that it can be called from a
+ * time=0 timeout.
+ *
+ * Calls @p callback with @p w->syntherr as the error code (which might be 0).
+ */
+static int writer_shutdown(ev_source *ev,
+ const attribute((unused)) struct timeval *now,
+ void *u) {
ev_writer *w = u;
+
+ if(w->fd == -1)
+ return 0; /* already shut down */
+ D(("writer_shutdown fd=%d error=%d", w->fd, w->error));
+ ev_timeout_cancel(ev, w->timeout);
+ ev_fd_cancel(ev, ev_write, w->fd);
+ w->timeout = 0;
+ if(w->reader) {
+ D(("found a tied reader"));
+ /* If there is a reader still around we just untie it */
+ w->reader->writer = 0;
+ shutdown(w->fd, SHUT_WR); /* there'll be no more writes */
+ } else {
+ D(("no tied reader"));
+ /* There's no reader so we are free to close the FD */
+ xclose(w->fd);
+ }
+ w->fd = -1;
+ return w->callback(ev, w->error, w->u);
+}
+
+/** @brief Called when a writer's @p timebound expires */
+static int writer_timebound_exceeded(ev_source *ev,
+ const struct timeval *now,
+ void *u) {
+ ev_writer *const w = u;
+
+ error(0, "abandoning writer %s because no writes within %ds",
+ w->what, w->timebound);
+ w->error = ETIMEDOUT;
+ return writer_shutdown(ev, now, u);
+}
+
+/** @brief Set the time bound callback (if not set already) */
+static void writer_set_timebound(ev_writer *w) {
+ if(w->timebound && !w->timeout) {
+ struct timeval when;
+ ev_source *const ev = w->ev;
+
+ xgettimeofday(&when, 0);
+ when.tv_sec += w->timebound;
+ ev_timeout(ev, &w->timeout, &when, writer_timebound_exceeded, w);
+ }
+}
+
+/** @brief Called when a writer's file descriptor is writable */
+static int writer_callback(ev_source *ev, int fd, void *u) {
+ ev_writer *const w = u;
int n;
n = write(fd, w->b.start, w->b.end - w->b.start);
D(("callback for writer fd %d, %ld bytes, n=%d, errno=%d",
fd, (long)(w->b.end - w->b.start), n, errno));
if(n >= 0) {
+ /* Consume bytes from the buffer */
w->b.start += n;
+ /* Suppress any outstanding timeout */
+ ev_timeout_cancel(ev, w->timeout);
+ w->timeout = 0;
if(w->b.start == w->b.end) {
+ /* The buffer is empty */
if(w->eof) {
- ev_fd_cancel(ev, ev_write, fd);
- return w->callback(ev, fd, 0, w->u);
+ /* We're done, we can shut down this writer */
+ w->error = 0;
+ return writer_shutdown(ev, 0, w);
} else
+ /* There might be more to come but we don't need writer_callback() to
+ * be called for the time being */
ev_fd_disable(ev, ev_write, fd);
- }
+ } else
+ /* The buffer isn't empty, set a timeout so we give up if we don't manage
+ * to write some more within a reasonable time */
+ writer_set_timebound(w);
} else {
switch(errno) {
case EINTR:
case EAGAIN:
break;
default:
- ev_fd_cancel(ev, ev_write, fd);
- return w->callback(ev, fd, errno, w->u);
+ w->error = errno;
+ return writer_shutdown(ev, 0, w);
}
}
return 0;
}
+/** @brief Write bytes to a writer's buffer
+ *
+ * This is the sink write callback.
+ *
+ * Calls ev_fd_enable() if necessary (i.e. if the buffer was empty but
+ * now is not).
+ */
static int ev_writer_write(struct sink *sk, const void *s, int n) {
ev_writer *w = (ev_writer *)sk;
-
+
+ if(!n)
+ return 0; /* avoid silliness */
+ if(w->fd == -1)
+ error(0, "ev_writer_write on %s after shutdown", w->what);
+ if(w->spacebound && w->b.end - w->b.start + n > w->spacebound) {
+ /* The new buffer contents will exceed the space bound. We assume that the
+ * remote client has gone away and TCP hasn't noticed yet, or that it's got
+ * hopelessly stuck. */
+ error(0, "abandoning writer %s because buffer has reached %td bytes",
+ w->what, w->b.end - w->b.start);
+ ev_fd_disable(w->ev, ev_write, w->fd);
+ w->error = EPIPE;
+ return ev_timeout(w->ev, 0, 0, writer_shutdown, w);
+ }
+ /* Make sure there is space */
buffer_space(&w->b, n);
+ /* If the buffer was formerly empty then we'll need to re-enable the FD */
if(w->b.start == w->b.end)
ev_fd_enable(w->ev, ev_write, w->fd);
memcpy(w->b.end, s, n);
w->b.end += n;
+ /* Arrange a timeout if there wasn't one set already */
+ writer_set_timebound(w);
return 0;
}
+/** @brief Create a new buffered writer
+ * @param ev Event loop
+ * @param fd File descriptor to write to
+ * @param callback Called if an error occurs and when finished
+ * @param u Passed to @p callback
+ * @param what Text description
+ * @return New writer or @c NULL
+ *
+ * Writers own their file descriptor and close it when they have finished with
+ * it.
+ *
+ * If you pass the same fd to a reader and writer, you must tie them together
+ * with ev_tie().
+ */
ev_writer *ev_writer_new(ev_source *ev,
int fd,
ev_error_callback *callback,
- void *u) {
+ void *u,
+ const char *what) {
ev_writer *w = xmalloc(sizeof *w);
D(("registering writer fd %d callback %p %p", fd, (void *)callback, u));
w->callback = callback;
w->u = u;
w->ev = ev;
- if(ev_fd(ev, ev_write, fd, writer_callback, w))
+ w->timebound = 10 * 60;
+ w->spacebound = 512 * 1024;
+ w->what = what;
+ if(ev_fd(ev, ev_write, fd, writer_callback, w, what))
return 0;
+ /* Buffer is initially empty so we don't want a callback */
ev_fd_disable(ev, ev_write, fd);
return w;
}
-struct sink *ev_writer_sink(ev_writer *w) {
- return &w->s;
+/** @brief Get/set the time bound
+ * @param w Writer
+ * @param new_time_bound New bound or -1 for no change
+ * @return Latest time bound
+ *
+ * If @p new_time_bound is negative then the current time bound is returned.
+ * Otherwise it is set and the new value returned.
+ *
+ * The time bound is the number of seconds allowed between writes. If it takes
+ * longer than this to flush a buffer then the peer will be assumed to be dead
+ * and an error will be synthesized. 0 means "don't care". The default time
+ * bound is 10 minutes.
+ *
+ * Note that this value does not take into account kernel buffering and
+ * timeouts.
+ */
+int ev_writer_time_bound(ev_writer *w,
+ int new_time_bound) {
+ if(new_time_bound >= 0)
+ w->timebound = new_time_bound;
+ return w->timebound;
}
-static int writer_shutdown(ev_source *ev,
- const attribute((unused)) struct timeval *now,
- void *u) {
- ev_writer *w = u;
+/** @brief Get/set the space bound
+ * @param w Writer
+ * @param new_space_bound New bound or -1 for no change
+ * @return Latest space bound
+ *
+ * If @p new_space_bound is negative then the current space bound is returned.
+ * Otherwise it is set and the new value returned.
+ *
+ * The space bound is the number of bytes allowed between in the buffer. If
+ * the buffer exceeds this size an error will be synthesized. 0 means "don't
+ * care". The default space bound is 512Kbyte.
+ *
+ * Note that this value does not take into account kernel buffering.
+ */
+int ev_writer_space_bound(ev_writer *w,
+ int new_space_bound) {
+ if(new_space_bound >= 0)
+ w->spacebound = new_space_bound;
+ return w->spacebound;
+}
- return w->callback(ev, w->fd, 0, w->u);
+/** @brief Return the sink associated with a writer
+ * @param w Writer
+ * @return Pointer to sink
+ *
+ * Writing to the sink will arrange for those bytes to be written to the file
+ * descriptor as and when it is writable.
+ */
+struct sink *ev_writer_sink(ev_writer *w) {
+ if(!w)
+ fatal(0, "ev_write_sink called with null writer");
+ return &w->s;
}
+/** @brief Close a writer
+ * @param w Writer to close
+ * @return 0 on success, non-0 on error
+ *
+ * Close a writer. No more bytes should be written to its sink.
+ *
+ * When the last byte has been written the callback will be called with an
+ * error code of 0. It is guaranteed that this will NOT happen before
+ * ev_writer_close() returns (although the file descriptor for the writer might
+ * be cancelled by the time it returns).
+ */
int ev_writer_close(ev_writer *w) {
D(("close writer fd %d", w->fd));
+ if(w->eof)
+ return 0; /* already closed */
w->eof = 1;
if(w->b.start == w->b.end) {
- /* we're already finished */
- ev_fd_cancel(w->ev, ev_write, w->fd);
+ /* We're already finished */
+ w->error = 0; /* no error */
return ev_timeout(w->ev, 0, 0, writer_shutdown, w);
}
return 0;
}
-int ev_writer_cancel(ev_writer *w) {
- D(("cancel writer fd %d", w->fd));
- return ev_fd_cancel(w->ev, ev_write, w->fd);
-}
-
+/** @brief Attempt to flush a writer
+ * @param w Writer to flush
+ * @return 0 on success, non-0 on error
+ *
+ * Does a speculative write of any buffered data. Does not block if it cannot
+ * be written.
+ */
int ev_writer_flush(ev_writer *w) {
return writer_callback(w->ev, w->fd, w);
}
/* buffered reader ************************************************************/
-struct ev_reader {
- struct buffer b;
- int fd;
- ev_reader_callback *callback;
- ev_error_callback *error_callback;
- void *u;
- ev_source *ev;
- int eof;
-};
+/** @brief Shut down a reader*
+ *
+ * This is the only path through which we cancel and close the file descriptor.
+ * As with the writer case it is given timeout signature to allow it be
+ * deferred to the next iteration of the event loop.
+ *
+ * We only call @p error_callback if @p error is nonzero (unlike the writer
+ * case).
+ */
+static int reader_shutdown(ev_source *ev,
+ const attribute((unused)) struct timeval *now,
+ void *u) {
+ ev_reader *const r = u;
+
+ if(r->fd == -1)
+ return 0; /* already shut down */
+ D(("reader_shutdown fd=%d", r->fd));
+ ev_fd_cancel(ev, ev_read, r->fd);
+ r->eof = 1;
+ if(r->writer) {
+ D(("found a tied writer"));
+ /* If there is a writer still around we just untie it */
+ r->writer->reader = 0;
+ shutdown(r->fd, SHUT_RD); /* there'll be no more reads */
+ } else {
+ D(("no tied writer found"));
+ /* There's no writer so we are free to close the FD */
+ xclose(r->fd);
+ }
+ r->fd = -1;
+ if(r->error)
+ return r->error_callback(ev, r->error, r->u);
+ else
+ return 0;
+}
+/** @brief Called when a reader's @p fd is readable */
static int reader_callback(ev_source *ev, int fd, void *u) {
ev_reader *r = u;
int n;
fd, (int)(r->b.top - r->b.end), n, errno));
if(n > 0) {
r->b.end += n;
- return r->callback(ev, r, fd, r->b.start, r->b.end - r->b.start, 0, r->u);
+ return r->callback(ev, r, r->b.start, r->b.end - r->b.start, 0, r->u);
} else if(n == 0) {
- r->eof = 1;
- ev_fd_cancel(ev, ev_read, fd);
- return r->callback(ev, r, fd, r->b.start, r->b.end - r->b.start, 1, r->u);
+ /* No more read callbacks needed */
+ ev_fd_disable(r->ev, ev_read, r->fd);
+ ev_timeout(r->ev, 0, 0, reader_shutdown, r);
+ /* Pass the remaining data and an eof indicator to the user */
+ return r->callback(ev, r, r->b.start, r->b.end - r->b.start, 1, r->u);
} else {
switch(errno) {
case EINTR:
case EAGAIN:
break;
default:
- ev_fd_cancel(ev, ev_read, fd);
- return r->error_callback(ev, fd, errno, r->u);
+ /* Fatal error, kill the reader now */
+ r->error = errno;
+ return reader_shutdown(ev, 0, r);
}
}
return 0;
}
+/** @brief Create a new buffered reader
+ * @param ev Event loop
+ * @param fd File descriptor to read from
+ * @param callback Called when new data is available
+ * @param error_callback Called if an error occurs
+ * @param u Passed to callbacks
+ * @param what Text description
+ * @return New reader or @c NULL
+ *
+ * Readers own their fd and close it when they are finished with it.
+ *
+ * If you pass the same fd to a reader and writer, you must tie them together
+ * with ev_tie().
+ */
ev_reader *ev_reader_new(ev_source *ev,
int fd,
ev_reader_callback *callback,
ev_error_callback *error_callback,
- void *u) {
+ void *u,
+ const char *what) {
ev_reader *r = xmalloc(sizeof *r);
D(("registering reader fd %d callback %p %p %p",
r->error_callback = error_callback;
r->u = u;
r->ev = ev;
- if(ev_fd(ev, ev_read, fd, reader_callback, r))
+ if(ev_fd(ev, ev_read, fd, reader_callback, r, what))
return 0;
return r;
}
buffer_space(&r->b, nbytes - (r->b.end - r->b.start));
}
+/** @brief Consume @p n bytes from the reader's buffer
+ * @param r Reader
+ * @param n Number of bytes to consume
+ *
+ * Tells the reader than the next @p n bytes have been dealt with and can now
+ * be discarded.
+ */
void ev_reader_consume(ev_reader *r, size_t n) {
r->b.start += n;
}
+/** @brief Cancel a reader
+ * @param r Reader
+ * @return 0 on success, non-0 on error
+ *
+ * No further callbacks will be made, and the FD will be closed (in a later
+ * iteration of the event loop).
+ */
int ev_reader_cancel(ev_reader *r) {
D(("cancel reader fd %d", r->fd));
- return ev_fd_cancel(r->ev, ev_read, r->fd);
+ if(r->fd == -1)
+ return 0; /* already thoroughly cancelled */
+ ev_fd_disable(r->ev, ev_read, r->fd);
+ return ev_timeout(r->ev, 0, 0, reader_shutdown, r);
}
+/** @brief Temporarily disable a reader
+ * @param r Reader
+ * @return 0 on success, non-0 on error
+ *
+ * No further callbacks for this reader will be made. Re-enable with
+ * ev_reader_enable().
+ */
int ev_reader_disable(ev_reader *r) {
D(("disable reader fd %d", r->fd));
- return r->eof ? 0 : ev_fd_disable(r->ev, ev_read, r->fd);
+ return ev_fd_disable(r->ev, ev_read, r->fd);
}
+/** @brief Called from ev_run() for ev_reader_incomplete() */
static int reader_continuation(ev_source attribute((unused)) *ev,
const attribute((unused)) struct timeval *now,
void *u) {
ev_reader *r = u;
D(("reader continuation callback fd %d", r->fd));
- if(ev_fd_enable(r->ev, ev_read, r->fd)) return -1;
- return r->callback(ev, r, r->fd, r->b.start, r->b.end - r->b.start, r->eof, r->u);
+ /* If not at EOF turn the FD back on */
+ if(!r->eof)
+ if(ev_fd_enable(r->ev, ev_read, r->fd))
+ return -1;
+ /* We're already in a timeout callback so there's no reason we can't call the
+ * user callback directly (compare ev_reader_enable()). */
+ return r->callback(ev, r, r->b.start, r->b.end - r->b.start, r->eof, r->u);
}
+/** @brief Arrange another callback
+ * @param r reader
+ * @return 0 on success, non-0 on error
+ *
+ * Indicates that the reader can process more input but would like to yield to
+ * other clients of the event loop. Input will be disabled but it will be
+ * re-enabled on the next iteration of the event loop and the read callback
+ * will be called again (even if no further bytes are available).
+ */
int ev_reader_incomplete(ev_reader *r) {
if(ev_fd_disable(r->ev, ev_read, r->fd)) return -1;
return ev_timeout(r->ev, 0, 0, reader_continuation, r);
ev_reader *r = u;
D(("reader enabled callback fd %d", r->fd));
- return r->callback(ev, r, r->fd, r->b.start, r->b.end - r->b.start, r->eof, r->u);
+ return r->callback(ev, r, r->b.start, r->b.end - r->b.start, r->eof, r->u);
}
+/** @brief Re-enable reading
+ * @param r reader
+ * @return 0 on success, non-0 on error
+ *
+ * If there is unconsumed data then you get a callback next time round the
+ * event loop even if nothing new has been read.
+ *
+ * The idea is in your read callback you come across a line (or whatever) that
+ * can't be processed immediately. So you set up processing and disable
+ * reading with ev_reader_disable(). Later when you finish processing you
+ * re-enable. You'll automatically get another callback directly from the
+ * event loop (i.e. not from inside ev_reader_enable()) so you can handle the
+ * next line (or whatever) if the whole thing has in fact already arrived.
+ *
+ * The difference between this process and calling ev_reader_incomplete() is
+ * ev_reader_incomplete() deals with the case where you can process now but
+ * would rather yield to other clients of the event loop, while using
+ * ev_reader_disable() and ev_reader_enable() deals with the case where you
+ * cannot process input yet because some other process is actually not
+ * complete.
+ */
int ev_reader_enable(ev_reader *r) {
D(("enable reader fd %d", r->fd));
- return ((r->eof ? 0 : ev_fd_enable(r->ev, ev_read, r->fd))
- || ev_timeout(r->ev, 0, 0, reader_enabled, r)) ? -1 : 0;
+
+ /* First if we're not at EOF then we re-enable reading */
+ if(!r->eof)
+ if(ev_fd_enable(r->ev, ev_read, r->fd))
+ return -1;
+ /* Arrange another callback next time round the event loop */
+ return ev_timeout(r->ev, 0, 0, reader_enabled, r);
+}
+
+/** @brief Tie a reader and a writer together
+ * @param r Reader
+ * @param w Writer
+ * @return 0 on success, non-0 on error
+ *
+ * This function must be called if @p r and @p w share a file descritptor.
+ */
+int ev_tie(ev_reader *r, ev_writer *w) {
+ assert(r->writer == 0);
+ assert(w->reader == 0);
+ r->writer = w;
+ w->reader = r;
+ return 0;
}
/*
~mdw / disorder / blobdiff