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| author | Laurent Bercot <ska-skaware@skarnet.org> | 2015-01-15 20:14:44 +0000 |
|---|---|---|
| committer | Laurent Bercot <ska-skaware@skarnet.org> | 2015-01-15 20:14:44 +0000 |
| commit | 87c5b2118efcee65eeda3f743d081ea9c2b866d9 (patch) | |
| tree | 31ca07d6134adf44bc3d58f4fcf4ea8be9cb7dbb /doc/libs6/s6-ftrigrd.html | |
| parent | cd2500fcc704287c4994a3253b593593c867913e (diff) | |
| download | s6-87c5b2118efcee65eeda3f743d081ea9c2b866d9.tar.xz | |
Move Unix domain utilities and access control utilites,
as well as the accessrules library, from s6-networking to here
Diffstat (limited to 'doc/libs6/s6-ftrigrd.html')
| -rw-r--r-- | doc/libs6/s6-ftrigrd.html | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/doc/libs6/s6-ftrigrd.html b/doc/libs6/s6-ftrigrd.html new file mode 100644 index 0000000..4bbfc69 --- /dev/null +++ b/doc/libs6/s6-ftrigrd.html @@ -0,0 +1,80 @@ +<html> + <head> + <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> + <meta http-equiv="Content-Language" content="en" /> + <title>s6: the s6-ftrigrd program</title> + <meta name="Description" content="s6: the s6-ftrigrd program" /> + <meta name="Keywords" content="s6 command s6-ftrigrd program internal libexec fifodir regexp subscribe notification listener" /> + <!-- <link rel="stylesheet" type="text/css" href="http://skarnet.org/default.css" /> --> + </head> +<body> + +<p> +<a href="index.html">libs6</a><br /> +<a href="../">s6</a><br /> +<a href="http://skarnet.org/software/">Software</a><br /> +<a href="http://skarnet.org/">skarnet.org</a> +</p> + +<h1> The s6-ftrigrd program </h1> + +<p> +s6-ftrigrd is a helper program that manages a set of subscriptions to fifodirs as well +as regular expressions on events. It takes orders from its client program that controls +it via the <a href="ftrigr.html">ftrigr library</a>, and notifies it when desired +events happen. +</p> + +<h2> Interface </h2> + +<p> + s6-ftrigrd is not meant to be called directly. +</p> + +<ul> + <li> If the client program uses <tt>ftrigr_startf()</tt>, it spawns an instance of +s6-ftrigrd as a child. s6-ftrigrd's stdin is a pipe reading from the client; its +stdout is a pipe writing to the client; its stderr is the same as the client's; and +there's an additional pipe from s6-ftrigrd to the client, used for asynchronous +notifications. </li> + <li> If the client program uses <tt>ftrigr_start()</tt>, then it tries to connect +to a Unix domain socket. A ftrigrd <a href="../localservice.html">local service</a> should be listening to that +socket, i.e. a Unix domain superserver such as +<a href="s6-ipcserver.html">s6-ipcserver</a> +spawning a s6-ftrigrd program on every connection. Then a s6-ftrigrd instance is created +for the client. </li> + <li> When the client uses <tt>ftrigr_end()</tt>, or closes s6-ftrigrd's stdin in +any way, s6-ftrigrd exits 0. </li> +</ul> + +<p> + s6-ftrigrd handles the grunt work of creating fifos in a +<a href="fifodir.html">fifodir</a> for a subscriber. It also wakes up on every +event, and compares the chain of events it received on a given fifodir with the +client-provided regexp. If the chain of events matches the regexp, it notifies +the client. +</p> + +<h2> Notes </h2> + +<p> + The connection management between the client and s6-ftrigrd is entirely done +by the <a href="http://skarnet.org/software/skalibs/libunixonacid/skaclient.html">skaclient</a> +library. +</p> + +<p> + s6-ftrigrd is entirely asynchronous. It stores unread notifications into heap +memory; it can grow in size if there are a lot of events and the client fails +to read them. To avoid uncontrolled growth, make sure your client calls +<tt>ftrigr_update()</tt> as soon as <tt>ftrigr_fd()</tt> becomes readable. +</p> + +<p> + A s6-ftrigrd instance can only handle up to FTRIGRD_MAX (defined in <tt>s6/ftrigr.h</tt>) +subscriptions at once. By default, this number is 1000, which is more than enough for +any reasonable system. +</p> + +</body> +</html> |