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Diffstat (limited to 'doc/s6-rc-compile.html')
| -rw-r--r-- | doc/s6-rc-compile.html | 47 |
1 files changed, 33 insertions, 14 deletions
diff --git a/doc/s6-rc-compile.html b/doc/s6-rc-compile.html index 14bec2f..4065689 100644 --- a/doc/s6-rc-compile.html +++ b/doc/s6-rc-compile.html @@ -287,19 +287,20 @@ be copied verbatim into the generated service directory. </li> it must contain the name of another longrun service <em>servicelog</em>; <em>service</em> is then declared as a producer for <em>servicelog</em>. <em>servicelog</em> must also, in its own definition directory, -be declared as a consumer for <em>service</em>. </li> +be declared as a consumer for at least <em>service</em>. </li> <li> An optional file named <tt>consumer-for</tt>. If this file exists, then -it must contain the name of another longrun service <em>serviceprod</em>; -<em>service</em> is then declared as a consumer for <em>serviceprod</em>. -<em>serviceprod</em> must also, in its own definition directory, +it must contain a list of longrun services <em>serviceprod...</em>: +<em>service</em> is then declared as a consumer for all the services +in <em>serviceprod</em>. Each of those services +must also, in its own definition directory, be declared as a producer for <em>service</em>. </li> <li> An optional file named <tt>pipeline-name</tt>. If this file exists -along with a <tt>producer-for</tt> file, and there is no -<tt>consumer-for</tt> file, then a bundle will automatically be +along with a <tt>consumer-for</tt> file, and there is no +<tt>producer-for</tt> file, then a bundle will automatically be created, named with the content of the <tt>pipeline-name</tt> file, and -containing all the services in the pipeline that starts at <em>service</em>. +containing all the services in the pipeline that ends at <em>service</em>. See below for more about pipelining. The <tt>pipeline-name</tt> file -is ignored if <em>service</em> is not a first producer. </li> +is ignored if <em>service</em> is not a last consumer. </li> </ul> <p> @@ -342,12 +343,12 @@ indefinite number of longrun services this way. </p> <ul> - <li> The first producer declares its direct consumer in a <tt>producer-for</tt> file. </li> - <li> Intermediate services declare both their direct producer in their + <li> A producer declares its direct consumer in a <tt>producer-for</tt> file. </li> + <li> Intermediate services declare both their direct producers in their <tt>consumer-for</tt> file, and their direct consumer in their <tt>producer-for</tt> file. </li> - <li> The last consumer only declares its direct producer in a <tt>consumer-for</tt> file. </li> - <li> The first producer may declare a name for the whole pipeline, in + <li> The last consumer only declares its direct producers in a <tt>consumer-for</tt> file. </li> + <li> The last consumer may also declare a name for the whole pipeline, in its <tt>pipeline-name</tt> file. If it does so, then a bundle is automatically created with the given name, and it contains all the services in the pipeline. </li> @@ -360,14 +361,32 @@ that the pipes are not broken whenever one element in the chain dies. </p> <p> + A service can only be declared as a producer for <em>one</em> other +services, but it can be declared as a consumer for several other +services: the <em>consumer-for</em> can have several lines. This +means that one service can only send its output to one consumer, but +it can read its input from several producers. If there are several +producers to a service, they will all write to the same Unix pipe +that the service reads. +</p> + +<p> + This means that what s6-rc calls <em>pipelines</em> are really +<em>funnels</em>: you can collapse multiple data streams into +a single data stream, at every step of your processing chain. +The <em>pipeline</em> terminology remains for history reasons: +previous versions of s6-rc could not handle multiple producers. +</p> + +<p> s6-rc-compile checks for pipeline consistency. It must see a -<tt>producer-for</tt> file in the producer's definition that is consistent +<tt>producer-for</tt> file in the producers' definition that is consistent with the <tt>consumer-for</tt> file in the consumer's definition. It will detect and reject cycles as well as collisions. </p> <p> - The pipe linking a producer with a consumer is created and stored at + The pipe linking a set of producers with a consumer is created and stored at run-time in a <a href="//skarnet.org/software/s6/s6-fdholder-daemon.html">s6-fdholder-daemon</a> instance managed by an automatically generated longrun service named |