<?xml version="1.0"?>

<!DOCTYPE module SYSTEM "../../../../dtd/module.dtd">

<module name="Module ngx_http_map_module"
        link="/en/docs/http/ngx_http_map_module.html"
        lang="en">

<section id="summary">

<para>
The <literal>ngx_http_map_module</literal> module creates variables
whose values depend on values of other variables.
</para>

</section>


<section id="example" name="Example Configuration">

<para>
<example>
map $http_host $name  {
    hostnames;

    default       0;

    example.com   1;
    *.example.com 1;
    test.com      2;
    *.test.com    2;
    .site.com     3;
    wap.*         4;
}
</example>
</para>

</section>


<section id="directives" name="Directives">

<directive name="map">
<syntax block="yes">
    <value>$variable1</value>
    <value>$variable2</value></syntax>
<default/>
<context>http</context>

<para>
Creates a variable whose value
depends on the value of another variable.
The directive supports three special parameters:
<list type="tag">
<tag-name><literal>default</literal> <value>value</value></tag-name>
<tag-desc>
sets a value for the second variable when the value
of the first variable cannot be found.
</tag-desc>

<tag-name><literal>hostnames</literal></tag-name>
<tag-desc>
allows to specify hostnames with a prefix or suffix mask, as source
values, for example,
<example>
*.example.com 1;
example.*     1;
</example>
The following two records
<example>
example.com   1;
*.example.com 1;
</example>
can be combined:
<example>
.example.com  1;
</example>
</tag-desc>

<tag-name><literal>include</literal> <value>file</value></tag-name>
<tag-desc>
includes a file with values.
There can be several inclusions.
</tag-desc>

</list>
</para>

</directive>


<directive name="map_hash_bucket_size">
<syntax><value>size</value></syntax>
<default>32|64|128</default>
<context>http</context>

<para>
Sets the bucket size for the <link id="map"/> variables hash tables.
Default value depends on the size of the processor's cache line.
For more information, please refer to
<link doc="../hash.xml">Setting Up Hashes</link>.
</para>

</directive>


<directive name="map_hash_max_size">
<syntax><value>size</value></syntax>
<default>2048</default>
<context>http</context>

<para>
Sets the maximum <value>size</value> of the <link id="map"/> variables
hash tables.
For more information, please refer to
<link doc="../hash.xml">Setting Up Hashes</link>.
</para>

</directive>

</section>

</module>