Example: call stdin_readable_cb when STDIN_FILENO has become, well readable, but only once. Since it is likely line-buffered, you could @@ -849,13 +871,34 @@

If the timer is repeating, either start it if necessary (with the repeat value), or reset the running timer to the repeat value.

This sounds a bit complicated, but here is a useful and typical -example: Imagine you have a tcp connection and you want a so-called idle -timeout, that is, you want to be called when there have been, say, 60 -seconds of inactivity on the socket. The easiest way to do this is to -configure an ev_timer with after=repeat=60 and calling ev_timer_again each -time you successfully read or write some data. If you go into an idle -state where you do not expect data to travel on the socket, you can stop -the timer, and again will automatically restart it if need be.

You can also ignore the after value and ev_timer_start altogether +and only ever use the repeat value:

This is more efficient then stopping/starting the timer eahc time you want +to modify its timeout value.

Example: call a callback every hour, or, more precisely, whenever the system clock is divisible by 3600. The callback invocation times have @@ -1041,6 +1096,10 @@

Configures the watcher to trigger on the given signal number (usually one of the SIGxxx constants).

ev_stat - did the file attributes just change?

This watches a filesystem path for attribute changes. That is, it calls +stat regularly (or when the OS says it changed) and sees if it changed +compared to the last time, invoking the callback if it did.

The path does not need to exist: changing from "path exists" to "path does +not exist" is a status change like any other. The condition "path does +not exist" is signified by the st_nlink field being zero (which is +otherwise always forced to be at least one) and all the other fields of +the stat buffer having unspecified contents.

Since there is no standard to do this, the portable implementation simply +calls stat (2) regulalry on the path to see if it changed somehow. You +can specify a recommended polling interval for this case. If you specify +a polling interval of 0 (highly recommended!) then a suitable, +unspecified default value will be used (which you can expect to be around +five seconds, although this might change dynamically). Libev will also +impose a minimum interval which is currently around 0.1, but thats +usually overkill.

This watcher type is not meant for massive numbers of stat watchers, +as even with OS-supported change notifications, this can be +resource-intensive.

At the time of this writing, no specific OS backends are implemented, but +if demand increases, at least a kqueue and inotify backend will be added.

ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)

ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)

Configures the watcher to wait for status changes of the given +path. The interval is a hint on how quickly a change is expected to +be detected and should normally be specified as 0 to let libev choose +a suitable value. The memory pointed to by path must point to the same +path for as long as the watcher is active.

The callback will be receive EV_STAT when a change was detected, +relative to the attributes at the time the watcher was started (or the +last change was detected).

ev_stat_stat (ev_stat *)

Updates the stat buffer immediately with new values. If you change the +watched path in your callback, you could call this fucntion to avoid +detecting this change (while introducing a race condition). Can also be +useful simply to find out the new values.

ev_statdata attr [read-only]

The most-recently detected attributes of the file. Although the type is of +ev_statdata, this is usually the (or one of the) struct stat types +suitable for your system. If the st_nlink member is 0, then there +was some error while stating the file.

ev_statdata prev [read-only]

The previous attributes of the file. The callback gets invoked whenever +prev != attr.

ev_tstamp interval [read-only]

The specified interval.

const char *path [read-only]

The filesystem path that is being watched.

Example: Watch /etc/passwd for attribute changes.

  static void
+  passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
+  {
+    /* /etc/passwd changed in some way */
+    if (w->attr.st_nlink)
+      {
+        printf ("passwd current size  %ld\n", (long)w->attr.st_size);
+        printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
+        printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
+      }
+    else
+      /* you shalt not abuse printf for puts */
+      puts ("wow, /etc/passwd is not there, expect problems. "
+            "if this is windows, they already arrived\n");
+  }
+
+  ...
+  ev_stat passwd;
+
+  ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
+  ev_stat_start (loop, &passwd);
+
+
+
+
+

+ +

ev_idle - when you've got nothing better to do...

Idle watchers trigger events when there are no other events are pending @@ -1306,6 +1471,10 @@ similarly to ev_loop (embedded_loop, EVLOOP_NONBLOCK), but in the most apropriate way for embedded loops.

struct ev_loop *loop [read-only]

The embedded event loop.

@@ -1704,10 +1873,27 @@ for multiple event loops and there is no first event loop pointer argument. Instead, all functions act on the single default loop.

EV_PERIODICS

EV_PERIODIC_ENABLE

If undefined or defined to be 1, then periodic timers are supported. If +defined to be 0, then they are not. Disabling them saves a few kB of +code.

EV_EMBED_ENABLE

If undefined or defined to be 1, then embed watchers are supported. If +defined to be 0, then they are not.

EV_STAT_ENABLE

If undefined or defined to be 1, then stat watchers are supported. If +defined to be 0, then they are not.

EV_MINIMAL

If undefined or defined to be 1, then periodic timers are supported, -otherwise not. This saves a few kb of code.

If you need to shave off some kilobytes of code at the expense of some +speed, define this symbol to 1. Currently only used for gcc to override +some inlining decisions, saves roughly 30% codesize of amd64.

EV_COMMON

WATCHER TYPES

`ev_stat` - did the file attributes just change?

`ev_idle` - when you've got nothing better to do...

WATCHER TYPES

ev_stat - did the file attributes just change?

ev_idle - when you've got nothing better to do...

`ev_stat` - did the file attributes just change?

`ev_idle` - when you've got nothing better to do...