diff options
Diffstat (limited to 'ev.html')
| -rw-r--r-- | ev.html | 18 |
1 files changed, 17 insertions, 1 deletions
@@ -6,7 +6,7 @@ <meta name="description" content="Pod documentation for libev" /> <meta name="inputfile" content="<standard input>" /> <meta name="outputfile" content="<standard output>" /> - <meta name="created" content="Fri Nov 23 06:14:47 2007" /> + <meta name="created" content="Fri Nov 23 09:26:40 2007" /> <meta name="generator" content="Pod::Xhtml 1.57" /> <link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head> <body> @@ -230,6 +230,9 @@ result in some caching, there is still a syscall per such incident (because the fd could point to a different file description now), so its best to avoid that. Also, dup()ed file descriptors might not work very well if you register events for both fds.</p> + <p>Please note that epoll sometimes generates spurious notifications, so you +need to use non-blocking I/O or other means to avoid blocking when no data +(or space) is available.</p> </dd> <dt><code>EVBACKEND_KQUEUE</code> (value 8, most BSD clones)</dt> <dd> @@ -252,6 +255,9 @@ incident, so its best to avoid that.</p> <dd> <p>This uses the Solaris 10 port mechanism. As with everything on Solaris, it's really slow, but it still scales very well (O(active_fds)).</p> + <p>Please note that solaris ports can result in a lot of spurious +notifications, so you need to use non-blocking I/O or other means to avoid +blocking when no data (or space) is available.</p> </dd> <dt><code>EVBACKEND_ALL</code></dt> <dd> @@ -550,6 +556,16 @@ the same underlying "file open").</p> <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | EV_WRITE</code> to receive the given events.</p> + <p>Please note that most of the more scalable backend mechanisms (for example +epoll and solaris ports) can result in spurious readyness notifications +for file descriptors, so you practically need to use non-blocking I/O (and +treat callback invocation as hint only), or retest separately with a safe +interface before doing I/O (XLib can do this), or force the use of either +<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this +problem. Also note that it is quite easy to have your callback invoked +when the readyness condition is no longer valid even when employing +typical ways of handling events, so its a good idea to use non-blocking +I/O unconditionally.</p> </dd> </dl> |