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Caching
— Mako 0.3.6 Documentation</title>
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<h1>Mako 0.3.6 Documentation</h1>
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Version: <span class="versionnum">0.3.6</span> Last Updated: 11/13/2010 16:04:30
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Caching
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<h2>
Caching
</h2>
</div>
<ul>
<li><a class="reference internal" href="#">Caching</a><ul>
<li><a class="reference internal" href="#cache-arguments">Cache arguments</a></li>
<li><a class="reference internal" href="#accessing-the-cache">Accessing the Cache</a></li>
<li><a class="reference internal" href="#api-reference">API Reference</a></li>
</ul>
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<div class="section" id="caching">
<span id="caching-toplevel"></span><h1>Caching<a class="headerlink" href="#caching" title="Permalink to this headline">¶</a></h1>
<p>Any template or component can be cached using the <tt class="docutils literal"><span class="pre">cache</span></tt>
argument to the <tt class="docutils literal"><span class="pre"><%page></span></tt> or <tt class="docutils literal"><span class="pre"><%def></span></tt> directives:</p>
<div class="highlight-mako"><div class="highlight"><pre><span class="cp"><%</span><span class="nb">page</span> <span class="na">cached=</span><span class="s">"True"</span><span class="cp">/></span><span class="x"></span>
<span class="x">template text</span>
</pre></div>
</div>
<p>The above template, after being executed the first time, will
store its content within a cache that by default is scoped
within memory. Subsequent calls to the template’s <a class="reference internal" href="usage.html#mako.template.Template.render" title="mako.template.Template.render"><tt class="xref py py-meth docutils literal"><span class="pre">render()</span></tt></a>
method will return content directly from the cache. When the
<a class="reference internal" href="usage.html#mako.template.Template" title="mako.template.Template"><tt class="xref py py-class docutils literal"><span class="pre">Template</span></tt></a> object itself falls out of scope, its corresponding
cache is garbage collected along with the template.</p>
<p>Caching requires that the <tt class="docutils literal"><span class="pre">beaker</span></tt> package be installed on the
system.</p>
<p>The caching flag and all its options can be used with the
<tt class="docutils literal"><span class="pre"><%def></span></tt> tag.</p>
<div class="highlight-mako"><div class="highlight"><pre><span class="cp"><%</span><span class="nb">def</span> <span class="na">name=</span><span class="s">"mycomp"</span> <span class="na">cached=</span><span class="s">"True"</span> <span class="na">cache_timeout=</span><span class="s">"30"</span> <span class="na">cache_type=</span><span class="s">"memory"</span><span class="cp">></span><span class="x"></span>
<span class="x"> other text</span>
<span class="cp"></%</span><span class="nb">def</span><span class="cp">></span><span class="x"></span>
</pre></div>
</div>
<div class="section" id="cache-arguments">
<h2>Cache arguments<a class="headerlink" href="#cache-arguments" title="Permalink to this headline">¶</a></h2>
<p>The various cache arguments are cascaded from their default
values, to the arguments specified programmatically to the
<a class="reference internal" href="usage.html#mako.template.Template" title="mako.template.Template"><tt class="xref py py-class docutils literal"><span class="pre">Template</span></tt></a> or its originating <a class="reference internal" href="usage.html#mako.lookup.TemplateLookup" title="mako.lookup.TemplateLookup"><tt class="xref py py-class docutils literal"><span class="pre">TemplateLookup</span></tt></a>, then to those
defined in the <tt class="docutils literal"><span class="pre"><%page></span></tt> tag of an individual template, and
finally to an individual <tt class="docutils literal"><span class="pre"><%def></span></tt> tag within the template. This
means you can define, for example, a cache type of <tt class="docutils literal"><span class="pre">dbm</span></tt> on your
<a class="reference internal" href="usage.html#mako.lookup.TemplateLookup" title="mako.lookup.TemplateLookup"><tt class="xref py py-class docutils literal"><span class="pre">TemplateLookup</span></tt></a>, a cache timeout of 60 seconds in a particular
template’s <tt class="docutils literal"><span class="pre"><%page></span></tt> tag, and within one of that template’s
<tt class="docutils literal"><span class="pre"><%def></span></tt> tags <tt class="docutils literal"><span class="pre">cache=True</span></tt>, and that one particular def will
then cache its data using a <tt class="docutils literal"><span class="pre">dbm</span></tt> cache and a data timeout of 60
seconds.</p>
<p>The options available are:</p>
<ul>
<li><p class="first"><tt class="docutils literal"><span class="pre">cached="False|True"</span></tt> - turn caching on</p>
</li>
<li><p class="first"><tt class="docutils literal"><span class="pre">cache_timeout</span></tt> - number of seconds in which to invalidate the
cached data. after this timeout, the content is re-generated
on the next call.</p>
</li>
<li><p class="first"><tt class="docutils literal"><span class="pre">cache_type</span></tt> - type of caching. <tt class="docutils literal"><span class="pre">memory</span></tt>, <tt class="docutils literal"><span class="pre">file</span></tt>, <tt class="docutils literal"><span class="pre">dbm</span></tt>, or
<tt class="docutils literal"><span class="pre">memcached</span></tt>.</p>
</li>
<li><p class="first"><tt class="docutils literal"><span class="pre">cache_url</span></tt> - (only used for <tt class="docutils literal"><span class="pre">memcached</span></tt> but required) a single
IP address or a semi-colon separated list of IP address of
memcache servers to use.</p>
</li>
<li><p class="first"><tt class="docutils literal"><span class="pre">cache_dir</span></tt> - In the case of the <tt class="docutils literal"><span class="pre">file</span></tt> and <tt class="docutils literal"><span class="pre">dbm</span></tt> cache types,
this is the filesystem directory with which to store data
files. If this option is not present, the value of
<tt class="docutils literal"><span class="pre">module_directory</span></tt> is used (i.e. the directory where compiled
template modules are stored). If neither option is available
an exception is thrown.</p>
<p>In the case of the <tt class="docutils literal"><span class="pre">memcached</span></tt> type, this attribute is required
and it’s used to store the lock files.</p>
</li>
<li><p class="first"><tt class="docutils literal"><span class="pre">cache_key</span></tt> - the “key” used to uniquely identify this content
in the cache. the total namespace of keys within the cache is
local to the current template, and the default value of “key”
is the name of the def which is storing its data. It is an
evaluable tag, so you can put a Python expression to calculate
the value of the key on the fly. For example, heres a page
that caches any page which inherits from it, based on the
filename of the calling template:</p>
</li>
</ul>
<div class="highlight-mako"><div class="highlight"><pre><span class="cp"><%</span><span class="nb">page</span> <span class="na">cached=</span><span class="s">"True"</span> <span class="na">cache_key=</span><span class="s">"${self.filename}"</span><span class="cp">/></span><span class="x"></span>
<span class="cp">${</span><span class="nb">next</span><span class="o">.</span><span class="n">body</span><span class="p">()</span><span class="cp">}</span>
<span class="cp">## rest of template</span><span class="x"></span>
</pre></div>
</div>
</div>
<div class="section" id="accessing-the-cache">
<h2>Accessing the Cache<a class="headerlink" href="#accessing-the-cache" title="Permalink to this headline">¶</a></h2>
<p>The <a class="reference internal" href="usage.html#mako.template.Template" title="mako.template.Template"><tt class="xref py py-class docutils literal"><span class="pre">Template</span></tt></a>, as well as any template-derived namespace, has
an accessor called <tt class="docutils literal"><span class="pre">cache</span></tt> which returns the <tt class="docutils literal"><span class="pre">Cache</span></tt> object
for that template. This object is a facade on top of the Beaker
internal cache object, and provides some very rudimental
capabilities, such as the ability to get and put arbitrary
values:</p>
<div class="highlight-mako"><div class="highlight"><pre><span class="cp"><%</span>
<span class="n">local</span><span class="o">.</span><span class="n">cache</span><span class="o">.</span><span class="n">put</span><span class="p">(</span><span class="s">"somekey"</span><span class="p">,</span> <span class="nb">type</span><span class="o">=</span><span class="s">"memory"</span><span class="p">,</span> <span class="s">"somevalue"</span><span class="p">)</span>
<span class="cp">%></span><span class="x"></span>
</pre></div>
</div>
<p>Above, the cache associated with the <tt class="docutils literal"><span class="pre">local</span></tt> namespace is
accessed and a key is placed within a memory cache.</p>
<p>More commonly the <tt class="docutils literal"><span class="pre">cache</span></tt> object is used to invalidate cached
sections programmatically:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">template</span> <span class="o">=</span> <span class="n">lookup</span><span class="o">.</span><span class="n">get_template</span><span class="p">(</span><span class="s">'/sometemplate.html'</span><span class="p">)</span>
<span class="c"># invalidate the "body" of the template</span>
<span class="n">template</span><span class="o">.</span><span class="n">cache</span><span class="o">.</span><span class="n">invalidate_body</span><span class="p">()</span>
<span class="c"># invalidate an individual def</span>
<span class="n">template</span><span class="o">.</span><span class="n">cache</span><span class="o">.</span><span class="n">invalidate_def</span><span class="p">(</span><span class="s">'somedef'</span><span class="p">)</span>
<span class="c"># invalidate an arbitrary key</span>
<span class="n">template</span><span class="o">.</span><span class="n">cache</span><span class="o">.</span><span class="n">invalidate</span><span class="p">(</span><span class="s">'somekey'</span><span class="p">)</span>
</pre></div>
</div>
</div>
<div class="section" id="api-reference">
<h2>API Reference<a class="headerlink" href="#api-reference" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="mako.cache.Cache">
<em class="property">class </em><tt class="descclassname">mako.cache.</tt><tt class="descname">Cache</tt><big>(</big><em>id</em>, <em>starttime</em><big>)</big><a class="headerlink" href="#mako.cache.Cache" title="Permalink to this definition">¶</a></dt>
<dd><p>Bases: <tt class="xref py py-class docutils literal"><span class="pre">object</span></tt></p>
<p>Represents a data content cache made available to the module
space of a <a class="reference internal" href="usage.html#mako.template.Template" title="mako.template.Template"><tt class="xref py py-class docutils literal"><span class="pre">Template</span></tt></a> object.</p>
<p><a class="reference internal" href="#mako.cache.Cache" title="mako.cache.Cache"><tt class="xref py py-class docutils literal"><span class="pre">Cache</span></tt></a> is a wrapper on top of a Beaker CacheManager object.
This object in turn references any number of “containers”, each of
which defines its own backend (i.e. file, memory, memcached, etc.)
independently of the rest.</p>
<dl class="method">
<dt id="mako.cache.Cache.get">
<tt class="descname">get</tt><big>(</big><em>key</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#mako.cache.Cache.get" title="Permalink to this definition">¶</a></dt>
<dd><p>Retrieve a value from the cache.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>key</strong> – the value’s key.</li>
<li><strong>**kwargs</strong> – cache configuration arguments. The
backend is configured using these arguments upon first request.
Subsequent requests that use the same series of configuration
values will use that same backend.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="mako.cache.Cache.invalidate">
<tt class="descname">invalidate</tt><big>(</big><em>key</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#mako.cache.Cache.invalidate" title="Permalink to this definition">¶</a></dt>
<dd><p>Invalidate a value in the cache.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>key</strong> – the value’s key.</li>
<li><strong>**kwargs</strong> – cache configuration arguments. The
backend is configured using these arguments upon first request.
Subsequent requests that use the same series of configuration
values will use that same backend.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="mako.cache.Cache.invalidate_body">
<tt class="descname">invalidate_body</tt><big>(</big><big>)</big><a class="headerlink" href="#mako.cache.Cache.invalidate_body" title="Permalink to this definition">¶</a></dt>
<dd><p>Invalidate the cached content of the “body” method for this template.</p>
</dd></dl>
<dl class="method">
<dt id="mako.cache.Cache.invalidate_closure">
<tt class="descname">invalidate_closure</tt><big>(</big><em>name</em><big>)</big><a class="headerlink" href="#mako.cache.Cache.invalidate_closure" title="Permalink to this definition">¶</a></dt>
<dd><p>Invalidate a nested <%def> within this template.</p>
<p>Caching of nested defs is a blunt tool as there is no
management of scope - nested defs that use cache tags
need to have names unique of all other nested defs in the
template, else their content will be overwritten by
each other.</p>
</dd></dl>
<dl class="method">
<dt id="mako.cache.Cache.invalidate_def">
<tt class="descname">invalidate_def</tt><big>(</big><em>name</em><big>)</big><a class="headerlink" href="#mako.cache.Cache.invalidate_def" title="Permalink to this definition">¶</a></dt>
<dd><p>Invalidate the cached content of a particular <%def> within this template.</p>
</dd></dl>
<dl class="method">
<dt id="mako.cache.Cache.put">
<tt class="descname">put</tt><big>(</big><em>key</em>, <em>value</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#mako.cache.Cache.put" title="Permalink to this definition">¶</a></dt>
<dd><p>Place a value in the cache.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>key</strong> – the value’s key.</li>
<li><strong>value</strong> – the value</li>
<li><strong>**kwargs</strong> – cache configuration arguments. The
backend is configured using these arguments upon first request.
Subsequent requests that use the same series of configuration
values will use that same backend.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
</dd></dl>
</div>
</div>
</div>
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