twisted.enterprise.adbapi.ConnectionPool.html [plain text]
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<a href="twisted.html">Package twisted</a> ::
<a href="twisted.enterprise.html">Package enterprise</a> ::
<a href="twisted.enterprise.adbapi.html">Module adbapi</a> ::
Class ConnectionPool
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<!-- =========== START OF CLASS DESCRIPTION =========== -->
<h2 class="class">Class ConnectionPool</h2>
<hr/>
<p>I represent a pool of connections to a DB-API 2.0 compliant
database.</p>
You can pass cp_min, cp_max or both to set the minimum and maximum
number of connections that will be opened by the pool. You can pass the
noisy arg which determines whether informational log messages are
generated during the pool's operation.
<hr/>
<!-- =========== START OF METHOD SUMMARY =========== -->
<table class="summary" border="1" cellpadding="3" cellspacing="0" width="100%" bgcolor="white">
<tr bgcolor="#70b0f0" class="summary">
<th colspan="2">Method Summary</th></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><a name="__init__"></a><span class="summary-sig"><span class="summary-sig-name">__init__</span>(<span class=summary-sig-arg>self</span>,
<span class=summary-sig-arg>dbapiName</span>,
<span class="summary-sig-vararg">*connargs</span>,
<span class="summary-sig-kwarg">**connkw</span>)</span></code>
</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><a name="__getstate__"></a><span class="summary-sig"><span class="summary-sig-name">__getstate__</span>(<span class=summary-sig-arg>self</span>)</span></code>
</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><a name="__setstate__"></a><span class="summary-sig"><span class="summary-sig-name">__setstate__</span>(<span class=summary-sig-arg>self</span>,
<span class=summary-sig-arg>state</span>)</span></code>
</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><span class="summary-sig"><a href="twisted.enterprise.adbapi.ConnectionPool.html#_deferToThread" class="summary-sig-name"><code>_deferToThread</code></a>(<span class=summary-sig-arg>self</span>,
<span class=summary-sig-arg>f</span>,
<span class="summary-sig-vararg">*args</span>,
<span class="summary-sig-kwarg">**kwargs</span>)</span></code>
<br />
Internal function.</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><a name="_runInteraction"></a><span class="summary-sig"><span class="summary-sig-name">_runInteraction</span>(<span class=summary-sig-arg>self</span>,
<span class=summary-sig-arg>interaction</span>,
<span class="summary-sig-vararg">*args</span>,
<span class="summary-sig-kwarg">**kw</span>)</span></code>
</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><a name="_runOperation"></a><span class="summary-sig"><span class="summary-sig-name">_runOperation</span>(<span class=summary-sig-arg>self</span>,
<span class="summary-sig-vararg">*args</span>,
<span class="summary-sig-kwarg">**kw</span>)</span></code>
</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><a name="_runQuery"></a><span class="summary-sig"><span class="summary-sig-name">_runQuery</span>(<span class=summary-sig-arg>self</span>,
<span class="summary-sig-vararg">*args</span>,
<span class="summary-sig-kwarg">**kw</span>)</span></code>
</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><span class="summary-sig"><a href="twisted.enterprise.adbapi.ConnectionPool.html#close" class="summary-sig-name"><code>close</code></a>(<span class=summary-sig-arg>self</span>)</span></code>
<br />
Close all pool connections and shutdown the pool.</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><span class="summary-sig"><a href="twisted.enterprise.adbapi.ConnectionPool.html#connect" class="summary-sig-name"><code>connect</code></a>(<span class=summary-sig-arg>self</span>)</span></code>
<br />
Return a database connection when one becomes available.</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><span class="summary-sig"><a href="twisted.enterprise.adbapi.ConnectionPool.html#finalClose" class="summary-sig-name"><code>finalClose</code></a>(<span class=summary-sig-arg>self</span>)</span></code>
<br />
This should only be called by the shutdown trigger.</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><a name="interaction"></a><span class="summary-sig"><span class="summary-sig-name">interaction</span>(<span class=summary-sig-arg>self</span>,
<span class=summary-sig-arg>interaction</span>,
<span class=summary-sig-arg>callback</span>,
<span class=summary-sig-arg>errback</span>,
<span class="summary-sig-vararg">*args</span>,
<span class="summary-sig-kwarg">**kw</span>)</span></code>
</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><a name="operation"></a><span class="summary-sig"><span class="summary-sig-name">operation</span>(<span class=summary-sig-arg>self</span>,
<span class=summary-sig-arg>callback</span>,
<span class=summary-sig-arg>errback</span>,
<span class="summary-sig-vararg">*args</span>,
<span class="summary-sig-kwarg">**kw</span>)</span></code>
</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><a name="query"></a><span class="summary-sig"><span class="summary-sig-name">query</span>(<span class=summary-sig-arg>self</span>,
<span class=summary-sig-arg>callback</span>,
<span class=summary-sig-arg>errback</span>,
<span class="summary-sig-vararg">*args</span>,
<span class="summary-sig-kwarg">**kw</span>)</span></code>
</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><span class="summary-sig"><a href="twisted.enterprise.adbapi.ConnectionPool.html#runInteraction" class="summary-sig-name"><code>runInteraction</code></a>(<span class=summary-sig-arg>self</span>,
<span class=summary-sig-arg>interaction</span>,
<span class="summary-sig-vararg">*args</span>,
<span class="summary-sig-kwarg">**kw</span>)</span></code>
<br />
Interact with the database and return the result.</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><span class="summary-sig"><a href="twisted.enterprise.adbapi.ConnectionPool.html#runOperation" class="summary-sig-name"><code>runOperation</code></a>(<span class=summary-sig-arg>self</span>,
<span class="summary-sig-vararg">*args</span>,
<span class="summary-sig-kwarg">**kw</span>)</span></code>
<br />
Execute an SQL query and return None.</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><span class="summary-sig"><a href="twisted.enterprise.adbapi.ConnectionPool.html#runQuery" class="summary-sig-name"><code>runQuery</code></a>(<span class=summary-sig-arg>self</span>,
<span class="summary-sig-vararg">*args</span>,
<span class="summary-sig-kwarg">**kw</span>)</span></code>
<br />
Execute an SQL query and return the result.</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><span class="summary-sig"><a href="twisted.enterprise.adbapi.ConnectionPool.html#start" class="summary-sig-name"><code>start</code></a>(<span class=summary-sig-arg>self</span>)</span></code>
<br />
Start the connection pool.</td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"> </font></td>
<td><code><a name="synchronousOperation"></a><span class="summary-sig"><span class="summary-sig-name">synchronousOperation</span>(<span class=summary-sig-arg>self</span>,
<span class="summary-sig-vararg">*args</span>,
<span class="summary-sig-kwarg">**kw</span>)</span></code>
</td></tr>
</table><br />
<!-- =========== START OF CLASS VARIABLE SUMMARY =========== -->
<table class="summary" border="1" cellpadding="3" cellspacing="0" width="100%" bgcolor="white">
<tr bgcolor="#70b0f0" class="summary">
<th colspan="2">Class Variable Summary</th></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"><code>int</code></font></td>
<td><b><a href="twisted.enterprise.adbapi.ConnectionPool.html#max"><code>max</code></a></b> = <span title="5">5 </span></td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"><code>int</code></font></td>
<td><b><a href="twisted.enterprise.adbapi.ConnectionPool.html#min"><code>min</code></a></b> = <span title="3">3 </span></td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"><code>int</code></font></td>
<td><b><a href="twisted.enterprise.adbapi.ConnectionPool.html#noisy"><code>noisy</code></a></b> = <span title="1">1 </span></td></tr>
<tr><td align="right" valign="top" width="15%"><font size="-1"><code>int</code></font></td>
<td><b><a href="twisted.enterprise.adbapi.ConnectionPool.html#running"><code>running</code></a></b> = <span title="0">0 </span></td></tr>
</table><br />
<!-- =========== START OF METHOD DETAILS =========== -->
<table class="details" border="1" cellpadding="3" cellspacing="0" width="100%" bgcolor="white">
<tr bgcolor="#70b0f0" class="details">
<th colspan="2">Method Details</th></tr>
</table>
<a name="_deferToThread"></a>
<table width="100%" class="func-details" bgcolor="#e0e0e0"><tr><td>
<h3><span class="sig"><span class="sig-name">_deferToThread</span>(<span class=sig-arg>self</span>,
<span class=sig-arg>f</span>,
<span class="sig-vararg">*args</span>,
<span class="sig-kwarg">**kwargs</span>)</span>
</h3>
<p>Internal function.</p>
Call f in one of the connection pool's threads.
<dl><dt></dt><dd>
</dd></dl>
</td></tr></table>
<a name="close"></a>
<table width="100%" class="func-details" bgcolor="#e0e0e0"><tr><td>
<h3><span class="sig"><span class="sig-name">close</span>(<span class=sig-arg>self</span>)</span>
</h3>
Close all pool connections and shutdown the pool.
<dl><dt></dt><dd>
</dd></dl>
</td></tr></table>
<a name="connect"></a>
<table width="100%" class="func-details" bgcolor="#e0e0e0"><tr><td>
<h3><span class="sig"><span class="sig-name">connect</span>(<span class=sig-arg>self</span>)</span>
</h3>
<p>Return a database connection when one becomes available.</p>
This method blocks and should be run in a thread from the internal
threadpool. Don't call this method directly from non-threaded twisted
code.
<dl><dt></dt><dd>
<dl><dt><b>Returns:</b></dt>
<dd>
a database connection from the pool.
</dd>
</dl>
</dd></dl>
</td></tr></table>
<a name="finalClose"></a>
<table width="100%" class="func-details" bgcolor="#e0e0e0"><tr><td>
<h3><span class="sig"><span class="sig-name">finalClose</span>(<span class=sig-arg>self</span>)</span>
</h3>
This should only be called by the shutdown trigger.
<dl><dt></dt><dd>
</dd></dl>
</td></tr></table>
<a name="runInteraction"></a>
<table width="100%" class="func-details" bgcolor="#e0e0e0"><tr><td>
<h3><span class="sig"><span class="sig-name">runInteraction</span>(<span class=sig-arg>self</span>,
<span class=sig-arg>interaction</span>,
<span class="sig-vararg">*args</span>,
<span class="sig-kwarg">**kw</span>)</span>
</h3>
<p>Interact with the database and return the result.</p>
<p>The 'interaction' is a callable object which will be executed in a
thread using a pooled connection. It will be passed an <a
href="twisted.enterprise.adbapi.Transaction.html"
class="link"><code>Transaction</code></a> object as an argument (whose
interface is identical to that of the database cursor for your DB-API
module of choice), and its results will be returned as a Deferred. If
running the method raises an exception, the transaction will be rolled
back. If the method returns a value, the transaction will be
committed.</p>
NOTE that the function you pass is *not* run in the main thread: you
may have to worry about thread-safety in the function you pass to this
if it tries to use non-local objects.
<dl><dt></dt><dd>
<dl><dt><b>Parameters:</b></dt>
<dd><code><b>interaction</b></code> -
a callable object whose first argument is <a
href="twisted.enterprise.adbapi.Transaction.html"
class="link"><code>adbapi.Transaction</code></a>. *args,**kw will
be passed as additional arguments.
</dd>
</dl>
<dl><dt><b>Returns:</b></dt>
<dd>
a Deferred which will fire the return value of
'interaction(Transaction(...))', or a Failure.
</dd>
</dl>
</dd></dl>
</td></tr></table>
<a name="runOperation"></a>
<table width="100%" class="func-details" bgcolor="#e0e0e0"><tr><td>
<h3><span class="sig"><span class="sig-name">runOperation</span>(<span class=sig-arg>self</span>,
<span class="sig-vararg">*args</span>,
<span class="sig-kwarg">**kw</span>)</span>
</h3>
<p>Execute an SQL query and return None.</p>
<p>A DB-API cursor will will be invoked with cursor.execute(*args,
**kw). The exact nature of the arguments will depend on the specific
flavor of DB-API being used, but the first argument in *args will be an
SQL statement. This method will not attempt to fetch any results from
the query and is thus suitable for INSERT, DELETE, and other SQL
statements which do not return values. If the 'execute' method raises
an exception, the transaction will be rolled back and a Failure
returned.</p>
<p>The args and kw arguments will be passed to the DB-API cursor's
'execute' method.</p>
return: a Deferred which will fire None or a Failure.
<dl><dt></dt><dd>
</dd></dl>
</td></tr></table>
<a name="runQuery"></a>
<table width="100%" class="func-details" bgcolor="#e0e0e0"><tr><td>
<h3><span class="sig"><span class="sig-name">runQuery</span>(<span class=sig-arg>self</span>,
<span class="sig-vararg">*args</span>,
<span class="sig-kwarg">**kw</span>)</span>
</h3>
<p>Execute an SQL query and return the result.</p>
<p>A DB-API cursor will will be invoked with cursor.execute(*args,
**kw). The exact nature of the arguments will depend on the specific
flavor of DB-API being used, but the first argument in *args be an SQL
statement. The result of a subsequent cursor.fetchall() will be fired
to the Deferred which is returned. If either the 'execute' or
'fetchall' methods raise an exception, the transaction will be rolled
back and a Failure returned.</p>
The *args and **kw arguments will be passed to the DB-API cursor's
'execute' method.
<dl><dt></dt><dd>
<dl><dt><b>Returns:</b></dt>
<dd>
a Deferred which will fire the return value of a DB-API
cursor's 'fetchall' method, or a Failure.
</dd>
</dl>
</dd></dl>
</td></tr></table>
<a name="start"></a>
<table width="100%" class="func-details" bgcolor="#e0e0e0"><tr><td>
<h3><span class="sig"><span class="sig-name">start</span>(<span class=sig-arg>self</span>)</span>
</h3>
<p>Start the connection pool.</p>
If you are using the reactor normally, this function does *not* need
to be called.
<dl><dt></dt><dd>
</dd></dl>
</td></tr></table>
<br />
<!-- =========== START OF CLASS VARIABLE DETAILS =========== -->
<table class="details" border="1" cellpadding="3" cellspacing="0" width="100%" bgcolor="white">
<tr bgcolor="#70b0f0" class="details">
<th colspan="2">Class Variable Details</th></tr>
</table>
<table width="100%" class="var-details" bgcolor="#e0e0e0"><tr><td>
<a name="max"></a>
<h3>max</h3>
<dl>
<dt></dt>
<dd>
<dl>
<dt><b>Type:</b></dt>
<dd>
<code>int</code>
</dd>
<span title="5"> <dt><b>Value:</b></dt>
<dd><table><tr><td>
<pre class="variable">
5 </pre>
</td></tr></table></dd>
</span> </dl>
</dd>
</dl></td></tr></table>
<table width="100%" class="var-details" bgcolor="#e0e0e0"><tr><td>
<a name="min"></a>
<h3>min</h3>
<dl>
<dt></dt>
<dd>
<dl>
<dt><b>Type:</b></dt>
<dd>
<code>int</code>
</dd>
<span title="3"> <dt><b>Value:</b></dt>
<dd><table><tr><td>
<pre class="variable">
3 </pre>
</td></tr></table></dd>
</span> </dl>
</dd>
</dl></td></tr></table>
<table width="100%" class="var-details" bgcolor="#e0e0e0"><tr><td>
<a name="noisy"></a>
<h3>noisy</h3>
<dl>
<dt></dt>
<dd>
<dl>
<dt><b>Type:</b></dt>
<dd>
<code>int</code>
</dd>
<span title="1"> <dt><b>Value:</b></dt>
<dd><table><tr><td>
<pre class="variable">
1 </pre>
</td></tr></table></dd>
</span> </dl>
</dd>
</dl></td></tr></table>
<table width="100%" class="var-details" bgcolor="#e0e0e0"><tr><td>
<a name="running"></a>
<h3>running</h3>
<dl>
<dt></dt>
<dd>
<dl>
<dt><b>Type:</b></dt>
<dd>
<code>int</code>
</dd>
<span title="0"> <dt><b>Value:</b></dt>
<dd><table><tr><td>
<pre class="variable">
0 </pre>
</td></tr></table></dd>
</span> </dl>
</dd>
</dl></td></tr></table>
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