Mailing List Archive

Author: des
Date: 2006-02-27 08:47:19 +0100 (Mon, 27 Feb 2006)
New Revision: 31

Modified:
trunk/varnish-doc/en/varnish-architecture/article.xml
Log:
Paste large portion of phk's notes.

Modified: trunk/varnish-doc/en/varnish-architecture/article.xml
===================================================================
--- trunk/varnish-doc/en/varnish-architecture/article.xml 2006-02-27 07:28:50 UTC (rev 30)
+++ trunk/varnish-doc/en/varnish-architecture/article.xml 2006-02-27 07:47:19 UTC (rev 31)
@@ -89,9 +89,8 @@
<title>Logger</title>

<para>The Logger keeps logs of various types of events in
- circular shared-memory buffers. These buffers must be managed
- using either POSIX shared memory primitives or file-backed
- mmap(2).</para>
+ circular shared-memory buffers. See <xref
+ linkend="sect.logging"/> for details.</para>

<para>It is the responsibility of each module to feed relevant
log data to the Logger.</para>
@@ -99,6 +98,144 @@
</section>
</section>

+ <section>
+ <title>Configuration</title>
+
+ <para>Policy is configured in a simple unidirectional (no loops,
+ no goto) programming language which is compiled into 'C' and from
+ there binary modules which are dlopen'ed by the main Varnish
+ process.</para>
+
+ <para>The dl object contains one exported symbol, a pointer to a
+ structure which contains a reference count, a number of function
+ pointers, a couple of string variables with identifying
+ information.</para>
+
+ <para>All access into the config is protected by the reference
+ counts.</para>
+
+ <para>Multiple policy configurations can be loaded at the same
+ time but only one is the "active configuration". Loading,
+ switching and unloading of policy configurations happen via the
+ managment process.</para>
+
+ <para>A global config sequence number is incremented on each
+ switch and policy modified object attributes (ttl, cache/nocache)
+ are all qualified by the config-sequence under which they were
+ calculated and invalid if a different policy is now in
+ effect.</para>
+ </section>
+
+ <section id="sect.logging">
+ <title>Logging</title>
+
+ <para>
+ </para>
+ </section>
+
+ <section id="sect.invalidation">
+ <title>Invalidation</title>
+
+ <para>When a purge request comes in, the regexp is tagged with the
+ next generation number and added to the tail of the list of purge
+ regexps.</para>
+
+ <para>Before a sender transmits an object, it is checked against
+ any purge-regexps which have higher generation number than the
+ object and if it matches the request is sent to a fetcher and the
+ object purged.</para>
+
+ <para>If there were purge regexps with higher generation to match,
+ but they didn't match, the object is tagged with the current
+ generation number and moved to the tail of the list.</para>
+
+ <para>Otherwise, the object does not change generation number and
+ is not moved on the generation list.</para>
+
+ <para>New Objects are tagged with the current generation number
+ and put at the tail of the list.</para>
+
+ <para>Objects are removed from the generation list when
+ deleted.</para>
+
+ <para>When a purge object has a lower generation number than the
+ first object on the generation list, the purge object has been
+ completed and will be removed. A log entry is written with number
+ of compares and number of hits.</para>
+ </section>
+
+ <section id="sect.management">
+ <title>Management</title>
+
+ <section>
+ <title>Management commands</title>
+
+ <itemizedlist>
+ <listitem>
+ <para>object_query url -&gt; TTL, size, checksum</para>
+ </listitem>
+ <listitem>
+ <para>{purge,invalidate} regexp</para>
+ </listitem>
+ <listitem>
+ <para>object_status url -&gt; object metadata</para>
+ </listitem>
+ <listitem>
+ <para>load_config filename</para>
+ </listitem>
+ <listitem>
+ <para>switch_config configname</para>
+ </listitem>
+ <listitem>
+ <para>list_configs</para>
+ </listitem>
+ <listitem>
+ <para>unload_config</para>
+ </listitem>
+ <listitem>
+ <para>freeze # stop the clock, freezes the object store</para>
+ </listitem>
+ <listitem>
+ <para>thaw</para>
+ </listitem>
+ <listitem>
+ <para>suspend # stop acceptor accepting new requests</para>
+ </listitem>
+ <listitem>
+ <para>resume</para>
+ </listitem>
+ <listitem>
+ <para>stop # forced stop (exits) varnish process</para>
+ </listitem>
+ <listitem>
+ <para>start</para>
+ </listitem>
+ <listitem>
+ <para>restart = "stop;start"</para>
+ </listitem>
+ <listitem>
+ <para>ping $utc_time -&gt; pong $utc_time</para>
+ </listitem>
+ <listitem>
+ <para>stats [-mr] -&gt; $data</para>
+ </listitem>
+ <listitem>
+ <para>zero stats</para>
+ </listitem>
+ <listitem>
+ <para>help</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>Cluster only:</para>
+ <itemizedlist>
+ <listitem>
+ <para>config_contents filename $inline -> compilation messages</para>
+ </listitem>
+ </itemizedlist>
+ </section>
+ </section>
+
<bibliography>
<title>References</title>