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authoryaworsky <yaworsky>2005-10-18 03:46:52 +0000
committeryaworsky <yaworsky>2005-10-18 03:46:52 +0000
commita3c53fe93626a09757cd83e3d253ab4dbf2f5488 (patch)
tree5105ab2a9a1f71bc361878165a6e2f0f1ab09656 /doc
parentdef1744fb0c11ee3656cbe6fcbd940532305f367 (diff)
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Added to CVS.
Diffstat (limited to 'doc')
-rw-r--r--doc/src/internals.xml83
-rw-r--r--doc/website/internals.xml17
2 files changed, 100 insertions, 0 deletions
diff --git a/doc/src/internals.xml b/doc/src/internals.xml
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+<para>
+There are three basic parts of daemon: listener, message processor and
+message writer.
+All these parts run in separate threads:
+the listener receives messages as fast as possible and passes them to the
+message processor,
+the message processor performs time-consuming tasks and
+message writer performs asynchronous output to files.
+</para>
+<para>
+Datagrams are received by the listener.
+The listener emits raw messages (struct raw_message) which contain content
+of datagram, sender address and reference to a source described
+in configuration file.
+</para>
+<para>
+Raw messages are passed to the processing thread via queue.
+Message processing involves the following tasks:
+ <itemizedlist>
+ <listitem>
+ <para>
+parse datagram:
+pick out PRI, TIMESTAMP, HOSTNAME, TAG an CONTENT according to
+<ulink url="http://www.ietf.org/rfc/rfc3164.txt">RFC 3164</ulink>;
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+convert CONTENT's encoding if specified;
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+determine sender host name if <option>usedns</option> option is set or just
+convert IP address to string;
+the result is saved in hostname cache to speed up subsequent resolutions;
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+multiplex message to logpaths and apply filters in logpaths;
+in other words, messages are multiplexed to logpaths through filters;
+messages in logpaths are represented with references to message structure
+and message structure contains reference count;
+ </para>
+ </listitem>
+ </itemizedlist>
+Because destination file name may be a pattern, further multiplexing is
+performed. Messages with similar HOSTNAME, TAG and CONTENT are coalesced.
+</para>
+<para>
+Log rotation is initiated at process startup or at writing thread startup.
+</para>
+<para>
+Old log files are deleted by the purger which is launched at process startup
+or by the writing thread after file is closed.
+ <screen>
++--------+ raw message +-----+ +------+ message +-----------------+
+|listener|------------>|queue|--->|parser|-------->|charset converter|--->
++--------+ +-----+ +------+ +-----------------+
+
+ +------+ +-----------+ +-----------+
+--->|filter|--->|multiplexer|-+->|destination|+
+ +------+ +-----------+ +->+-----------+|+
+ ^ +-> +-----------+|
+ | +-----------+
+ +-------+
+ |logpath|+
+ +-------+|+
+ +-------+|
+ +-------+
+
+
+ +-----------+ +-----+ +--------------+
+destination: >--|multiplexer|-+->|queue|+ ---> |writing thread|+
+ +-----------+ +->+-----+|+ ---> +--------------+|+
+ ^ +-> +-----+| ---> +--------------+|
+ | +-----+ +--------------+
+ +----------------+
+ |filename pattern|
+ +----------------+
+ </screen>
+</para>
diff --git a/doc/website/internals.xml b/doc/website/internals.xml
new file mode 100644
index 0000000..345ef40
--- /dev/null
+++ b/doc/website/internals.xml
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+<?xml version="1.0"?>
+<!DOCTYPE webpage PUBLIC "-//Norman Walsh//DTD Website Full V2.6.0//EN"
+ "http://docbook.sourceforge.net/release/website/current/schema/dtd/website-full.dtd" [
+ <!ENTITY internals SYSTEM "../src/internals.xml">
+]>
+
+<webpage id="internals">
+
+<config param="rcsdate" value="$Date: 2005/10/18 03:48:37 $"/>
+
+<head>
+ <title>Internals</title>
+</head>
+
+&internals;
+
+</webpage>