<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title> examples.dogpile_caching.environment — SQLAlchemy 1.2 Documentation </title> <!-- begin iterate through site-imported + sphinx environment css_files --> <link rel="stylesheet" href="../../../_static/pygments.css" type="text/css" /> <link rel="stylesheet" href="../../../_static/docs.css" type="text/css" /> <link rel="stylesheet" href="../../../_static/changelog.css" type="text/css" /> <link rel="stylesheet" href="../../../_static/sphinx_paramlinks.css" type="text/css" /> <!-- end iterate through site-imported + sphinx environment css_files --> <!-- begin layout.mako headers --> <link rel="index" title="Index" href="../../../genindex.html" /> <link rel="search" title="Search" href="../../../search.html" /> <link rel="copyright" title="Copyright" href="../../../copyright.html" /> <link rel="top" title="SQLAlchemy 1.2 Documentation" href="../../../index.html" /> <link rel="up" title="Module code" href="../../index.html" /> <!-- end layout.mako headers --> </head> <body> <div id="docs-container"> <div id="docs-top-navigation-container" class="body-background"> <div id="docs-header"> <div id="docs-version-header"> Release: <span class="version-num">1.2.19</span> | Release Date: April 15, 2019 </div> <h1>SQLAlchemy 1.2 Documentation</h1> </div> </div> <div id="docs-body-container"> <div id="fixed-sidebar" class=""> <div id="index-nav"> <form class="search" action="../../../search.html" method="get"> <label> Search terms: <input type="text" placeholder="search..." name="q" size="12" /> </label> <input type="submit" value="Search" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> <p> <a href="../../../contents.html">Contents</a> | <a href="../../../genindex.html">Index</a> </p> </div> </div> <div id="docs-body" class="" > <h1>Source code for examples.dogpile_caching.environment</h1><div class="highlight"><pre> <span></span><span class="sd">"""Establish data / cache file paths, and configurations,</span> <span class="sd">bootstrap fixture data if necessary.</span> <span class="sd">"""</span> <span class="kn">from</span> <span class="nn">hashlib</span> <span class="k">import</span> <span class="n">md5</span> <span class="kn">import</span> <span class="nn">os</span> <span class="kn">import</span> <span class="nn">sys</span> <span class="kn">from</span> <span class="nn">dogpile.cache.region</span> <span class="k">import</span> <span class="n">make_region</span> <span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">create_engine</span> <span class="kn">from</span> <span class="nn">sqlalchemy.ext.declarative</span> <span class="k">import</span> <span class="n">declarative_base</span> <span class="kn">from</span> <span class="nn">sqlalchemy.orm</span> <span class="k">import</span> <span class="n">scoped_session</span> <span class="kn">from</span> <span class="nn">sqlalchemy.orm</span> <span class="k">import</span> <span class="n">sessionmaker</span> <span class="kn">from</span> <span class="nn">.</span> <span class="k">import</span> <span class="n">caching_query</span> <span class="n">py2k</span> <span class="o">=</span> <span class="n">sys</span><span class="o">.</span><span class="n">version_info</span> <span class="o"><</span> <span class="p">(</span><span class="mi">3</span><span class="p">,</span> <span class="mi">0</span><span class="p">)</span> <span class="k">if</span> <span class="n">py2k</span><span class="p">:</span> <span class="nb">input</span> <span class="o">=</span> <span class="n">raw_input</span> <span class="c1"># noqa</span> <span class="c1"># dogpile cache regions. A home base for cache configurations.</span> <span class="n">regions</span> <span class="o">=</span> <span class="p">{}</span> <span class="c1"># scoped_session. Apply our custom CachingQuery class to it,</span> <span class="c1"># using a callable that will associate the dictionary</span> <span class="c1"># of regions with the Query.</span> <span class="n">Session</span> <span class="o">=</span> <span class="n">scoped_session</span><span class="p">(</span> <span class="n">sessionmaker</span><span class="p">(</span><span class="n">query_cls</span><span class="o">=</span><span class="n">caching_query</span><span class="o">.</span><span class="n">query_callable</span><span class="p">(</span><span class="n">regions</span><span class="p">))</span> <span class="p">)</span> <span class="c1"># global declarative base class.</span> <span class="n">Base</span> <span class="o">=</span> <span class="n">declarative_base</span><span class="p">()</span> <span class="n">root</span> <span class="o">=</span> <span class="s2">"./dogpile_data/"</span> <span class="k">if</span> <span class="ow">not</span> <span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">exists</span><span class="p">(</span><span class="n">root</span><span class="p">):</span> <span class="nb">input</span><span class="p">(</span> <span class="s2">"Will create datafiles in </span><span class="si">%r</span><span class="s2">.</span><span class="se">\n</span><span class="s2">"</span> <span class="s2">"To reset the cache + database, delete this directory.</span><span class="se">\n</span><span class="s2">"</span> <span class="s2">"Press enter to continue.</span><span class="se">\n</span><span class="s2">"</span> <span class="o">%</span> <span class="n">root</span> <span class="p">)</span> <span class="n">os</span><span class="o">.</span><span class="n">makedirs</span><span class="p">(</span><span class="n">root</span><span class="p">)</span> <span class="n">dbfile</span> <span class="o">=</span> <span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">root</span><span class="p">,</span> <span class="s2">"dogpile_demo.db"</span><span class="p">)</span> <span class="n">engine</span> <span class="o">=</span> <span class="n">create_engine</span><span class="p">(</span><span class="s2">"sqlite:///</span><span class="si">%s</span><span class="s2">"</span> <span class="o">%</span> <span class="n">dbfile</span><span class="p">,</span> <span class="n">echo</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span> <span class="n">Session</span><span class="o">.</span><span class="n">configure</span><span class="p">(</span><span class="n">bind</span><span class="o">=</span><span class="n">engine</span><span class="p">)</span> <span class="k">def</span> <span class="nf">md5_key_mangler</span><span class="p">(</span><span class="n">key</span><span class="p">):</span> <span class="sd">"""Receive cache keys as long concatenated strings;</span> <span class="sd"> distill them into an md5 hash.</span> <span class="sd"> """</span> <span class="k">return</span> <span class="n">md5</span><span class="p">(</span><span class="n">key</span><span class="o">.</span><span class="n">encode</span><span class="p">(</span><span class="s2">"ascii"</span><span class="p">))</span><span class="o">.</span><span class="n">hexdigest</span><span class="p">()</span> <span class="c1"># configure the "default" cache region.</span> <span class="n">regions</span><span class="p">[</span><span class="s2">"default"</span><span class="p">]</span> <span class="o">=</span> <span class="n">make_region</span><span class="p">(</span> <span class="c1"># the "dbm" backend needs</span> <span class="c1"># string-encoded keys</span> <span class="n">key_mangler</span><span class="o">=</span><span class="n">md5_key_mangler</span> <span class="p">)</span><span class="o">.</span><span class="n">configure</span><span class="p">(</span> <span class="c1"># using type 'file' to illustrate</span> <span class="c1"># serialized persistence. Normally</span> <span class="c1"># memcached or similar is a better choice</span> <span class="c1"># for caching.</span> <span class="s2">"dogpile.cache.dbm"</span><span class="p">,</span> <span class="n">expiration_time</span><span class="o">=</span><span class="mi">3600</span><span class="p">,</span> <span class="n">arguments</span><span class="o">=</span><span class="p">{</span><span class="s2">"filename"</span><span class="p">:</span> <span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">root</span><span class="p">,</span> <span class="s2">"cache.dbm"</span><span class="p">)},</span> <span class="p">)</span> <span class="c1"># optional; call invalidate() on the region</span> <span class="c1"># once created so that all data is fresh when</span> <span class="c1"># the app is restarted. Good for development,</span> <span class="c1"># on a production system needs to be used carefully</span> <span class="c1"># regions['default'].invalidate()</span> <span class="n">installed</span> <span class="o">=</span> <span class="kc">False</span> <span class="k">def</span> <span class="nf">bootstrap</span><span class="p">():</span> <span class="k">global</span> <span class="n">installed</span> <span class="kn">from</span> <span class="nn">.</span> <span class="k">import</span> <span class="n">fixture_data</span> <span class="k">if</span> <span class="ow">not</span> <span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">exists</span><span class="p">(</span><span class="n">dbfile</span><span class="p">):</span> <span class="n">fixture_data</span><span class="o">.</span><span class="n">install</span><span class="p">()</span> <span class="n">installed</span> <span class="o">=</span> <span class="kc">True</span></pre></div> </div> </div> <div id="docs-bottom-navigation" class="docs-navigation-links"> <div id="docs-copyright"> © <a href="../../../copyright.html">Copyright</a> 2007-2019, the SQLAlchemy authors and contributors. 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