From f8658e86c8237cebb1d0ce41f28e2715b983a532 Mon Sep 17 00:00:00 2001 From: Laurent Bercot Date: Sun, 28 Feb 2016 11:58:41 +0000 Subject: Add s6-rc-fdholder-filler doc --- doc/index.html | 1 + doc/s6-rc-fdholder-filler.html | 95 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 96 insertions(+) create mode 100644 doc/s6-rc-fdholder-filler.html diff --git a/doc/index.html b/doc/index.html index 06e92bf..897a777 100644 --- a/doc/index.html +++ b/doc/index.html @@ -114,6 +114,7 @@ the previous versions of s6-rc and the current one.

Related resources

diff --git a/doc/s6-rc-fdholder-filler.html b/doc/s6-rc-fdholder-filler.html new file mode 100644 index 0000000..83132fd --- /dev/null +++ b/doc/s6-rc-fdholder-filler.html @@ -0,0 +1,95 @@ + + + + + + s6-rc: the s6-rc-fdholder-filler program + + + + + + +

+s6-rc
+Software
+skarnet.org +

+ +

The s6-rc-fdholder-filler internal program

+ +

+ s6-rc-fdholder-filler creates anonymous pipes and stores them into a +s6-fdholderd +"fd-holding" daemon. +

+ +

+ s6-rc-fdholder-filler is not meant to be used directly; it is used +in internal scripts created by +s6-rc-compile, which are invoked during an +s6-rc execution. +

+ +

Interface

+ +

+     s6-rc-fdholder-filler [ -1 ] [ -t timeout ] longrunnames...
+

+ +

s6-rc-fdholder-filler expects file descriptor 6 to be open and +connected to the +s6-fdholderd +daemon instance managed by s6-rc as the internal s6rc-fdholder service.
For every argument longrun in longrunnames..., it +creates an anonymous pipe, and stores both ends of that pipe into the +s6-fdholderd +instance, with the pipe:s6-rc-r-longrun (for the reading +end) and pipe:s6-rc-w-longrun (for the writing end) +identifiers, and an infinite timeout.
It then exits 0.

+ +

Options

+ +

-1 : write a newline to stdout before exiting after +successful operation. This is used as a notification mechanism.
-t timeout : if the operation cannot be +achieved in timeout milliseconds, abort and report failure. By +default, timeout is 0, meaning infinite.

+ +

Exit codes

+ +

0: success
100: wrong usage
111: system call failed

+ +

Notes

+ +

s6-rc-fdholder-filler is never meant to be used manually; this page +should only be used to understand s6-rc internals.
s6-rc-fdholder-filler is used in the s6rc-fdholder internal +service's run script, right after the +s6-fdholderd +daemon is started; its arguments are the names of all the consumer longrun +services declared in the service database.
The point is to create all the pipes for the longrun pipelines in +advance, every time the s6rc-fdholder service is started, and +make them available in the fd holder. This way, pipelined services +can simply retrieve their stdin (for consumers) or stdout (for producers) +from the fd holder, at any time: even if a pipeline service dies and is +restarted, the pipe will remain valid.
If the fd holder itself dies, it will be refilled with a new set +of pipes as soon as it is restarted. Pipelined services will not be +impacted until one of them restarts; then all the pipeline will +restart.

+ + + -- cgit v1.2.3