Author: wyoung
Date: Thu Jul 12 03:03:52 2007
New Revision: 1670
URL: http://svn.gna.org/viewcvs/mysqlpp?rev=1670&view=rev
Log:
First cut at new ConnectionPool class. Compiles and looks good, but to
really test it, we'll need to get thread safety stuff in place.
Added:
trunk/lib/cpool.cpp
trunk/lib/cpool.h
Modified:
trunk/Wishlist
trunk/mysql++.bkl
Modified: trunk/Wishlist
URL:
http://svn.gna.org/viewcvs/mysqlpp/trunk/Wishlist?rev=1670&r1=1669&r2=1670&view=diff
==============================================================================
--- trunk/Wishlist (original)
+++ trunk/Wishlist Thu Jul 12 03:03:52 2007
@@ -14,10 +14,6 @@
it can be done without breaking the ABI, which would force
a feature to v3.0.
- o Add ConnectionPool class, described in this post:
-
- http://lists.mysql.com/plusplus/6631
-
o Extend the manipulators to handle nullable versions of
the types we already support. Should just be a matter of
duplicating the existing type-specific manipulator functions,
Added: trunk/lib/cpool.cpp
URL: http://svn.gna.org/viewcvs/mysqlpp/trunk/lib/cpool.cpp?rev=1670&view=auto
==============================================================================
--- trunk/lib/cpool.cpp (added)
+++ trunk/lib/cpool.cpp Thu Jul 12 03:03:52 2007
@@ -1,0 +1,86 @@
+/***********************************************************************
+ cpool.cpp - Implements the ConnectionPool class.
+
+ Copyright (c) 2007 by Educational Technology Resources, Inc.
+ Others may also hold copyrights on code in this file. See the
+ CREDITS file in the top directory of the distribution for details.
+
+ This file is part of MySQL++.
+
+ MySQL++ is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published
+ by the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ MySQL++ is distributed in the hope that it will be useful, but WITHOUT
+ ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+ License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with MySQL++; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
+ USA
+***********************************************************************/
+
+#include "cpool.h"
+
+#include "connection.h"
+
+namespace mysqlpp {
+
+
+//// connection ////////////////////////////////////////////////////////
+
+Connection*
+ConnectionPool::connection()
+{
+ lock();
+
+ // Find first unused connection in the pool
+ PoolIt it = pool_.begin();
+ while ((it != pool_.end()) && it->in_use) {
+ ++it;
+ }
+
+ if (it != pool_.end()) {
+ // Found at least one unused connection. Try to find more, and
+ // decide which is the most recently used.
+ unsigned int tmax = max_idle_time();
+ time_t now = time(0);
+ PoolIt mru = it;
+ ++it;
+ while (it != pool_.end()) {
+ if (it->in_use) {
+ // Can't use this one, it's busy
+ ++it;
+ }
+ else if ((now - it->last_used) > tmax) {
+ // This one's too old; nuke it
+ PoolIt doomed = it;
+ ++it;
+ pool_.erase(doomed);
+ }
+ else if (it->last_used > mru->last_used) {
+ // Ah, found a free one more recently used;
hang onto it
+ mru = it;
+ ++it;
+ }
+ }
+
+ mru->in_use = true;
+ unlock();
+ return mru->conn;
+ }
+ else {
+ // Pool was empty when this function was called, so create and
+ // return a new one.
+ pool_.push_back(ConnectionInfo(create()));
+ Connection* pc = pool_.back().conn;
+ unlock();
+ return pc;
+ }
+}
+
+} // end namespace mysqlpp
+
Added: trunk/lib/cpool.h
URL: http://svn.gna.org/viewcvs/mysqlpp/trunk/lib/cpool.h?rev=1670&view=auto
==============================================================================
--- trunk/lib/cpool.h (added)
+++ trunk/lib/cpool.h Thu Jul 12 03:03:52 2007
@@ -1,0 +1,128 @@
+/// \file cpool.h
+/// \brief Declares the ConnectionPool class.
+
+/***********************************************************************
+ Copyright (c) 2007 by Educational Technology Resources, Inc.
+ Others may also hold copyrights on code in this file. See the
+ CREDITS file in the top directory of the distribution for details.
+
+ This file is part of MySQL++.
+
+ MySQL++ is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published
+ by the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ MySQL++ is distributed in the hope that it will be useful, but WITHOUT
+ ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+ License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with MySQL++; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
+ USA
+***********************************************************************/
+
+#if !defined(MYSQLPP_CPOOL_H)
+#define MYSQLPP_CPOOL_H
+
+#include "common.h"
+#include "lockable.h"
+
+#include <list>
+
+#include <time.h>
+
+namespace mysqlpp {
+
+#if !defined(DOXYGEN_IGNORE)
+// Make Doxygen ignore this
+class MYSQLPP_EXPORT Connection;
+#endif
+
+/// \brief A class to manage a pool of connections, for use in a
+/// multi-threaded program to allow multiple simultaneous queries.
+///
+/// This class manages a pool of active database connections. This is
+/// useful in a multi-threaded program, because the MySQL C API doesn't
+/// permit multiple simultaneous operations on a single connection. You
+/// can get around this limitation by having multiple connections, but
+/// this isn't easy to do well. This class does it well. :)
+///
+/// The pool use policy is to always use the most recently used
+/// connection that's not being used right now. This ensures that
+/// excess connections get killed off reasonably quickly. By contrast,
+/// picking the least recently used connection can result in a large
+/// pool of sparsely used connections because we'd keep resetting the
+/// last-used time of the least recently used connection.
+
+class ConnectionPool : public Lockable
+{
+public:
+ /// \brief Default ctor
+ ConnectionPool() :
+ Lockable(false)
+ {
+ }
+
+ /// \brief Dtor
+ virtual ~ConnectionPool() { }
+
+ /// \brief Get the most recently used connection in the pool.
+ ///
+ /// This method creates a new connection if an unused one doesn't
+ /// exist, and destroys any that have remained unused for too long.
+ ///
+ /// \retval a pointer to the most recently used connection
+ Connection* connection();
+
+protected:
+ //// Subclass overrides
+ /// \brief Create a new connection
+ ///
+ /// Subclasses must override this.
+ ///
+ /// Essentially, this method lets your code tell ConnectionPool
+ /// what server to connect to, what login parameters to use, what
+ /// connection options to enable, etc. ConnectionPool can't know
+ /// any of this without your help.
+ ///
+ /// \retval A connected Connection object
+ virtual Connection* create() = 0;
+
+ /// \brief Returns the maximum number of seconds a connection is
+ /// able to remain idle before it is dropped.
+ ///
+ /// Subclasses must override this as it encodes a policy issue,
+ /// something that MySQL++ can't declare by fiat.
+ ///
+ /// \retval number of seconds before an idle connection is destroyed
+ /// due to lack of use
+ virtual unsigned int max_idle_time() = 0;
+
+private:
+ //// Internal types
+ struct ConnectionInfo {
+ Connection* conn;
+ time_t last_used;
+ bool in_use;
+
+ ConnectionInfo(Connection* c) :
+ conn(c),
+ last_used(time(0)),
+ in_use(true)
+ {
+ }
+ };
+ typedef std::list<ConnectionInfo> PoolT;
+ typedef PoolT::iterator PoolIt;
+
+ //// Internal data
+ PoolT pool_;
+};
+
+} // end namespace mysqlpp
+
+#endif // !defined(MYSQLPP_CPOOL_H)
+
Modified: trunk/mysql++.bkl
URL:
http://svn.gna.org/viewcvs/mysqlpp/trunk/mysql%2B%2B.bkl?rev=1670&r1=1669&r2=1670&view=diff
==============================================================================
--- trunk/mysql++.bkl (original)
+++ trunk/mysql++.bkl Thu Jul 12 03:03:52 2007
@@ -41,6 +41,7 @@
<sources>
lib/coldata.cpp
lib/connection.cpp
+ lib/cpool.cpp
lib/datetime.cpp
lib/field_names.cpp
lib/fields.cpp
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