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/*
* Copyright (C) 2007 Tommi Maekitalo
*
* This library 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.
*
* As a special exception, you may use this file as part of a free
* software library without restriction. Specifically, if other files
* instantiate templates or use macros or inline functions from this
* file, or you compile this file and link it with other files to
* produce an executable, this file does not by itself cause the
* resulting executable to be covered by the GNU General Public
* License. This exception does not however invalidate any other
* reasons why the executable file might be covered by the GNU Library
* General Public License.
*
* This library 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <iostream>
#include <cxxtools/thread.h>
#include <cxxtools/pool.h>
#include <cxxtools/log.h>
#include <unistd.h>
log_define("pooldemo")
// define a dummy dbconnection-object
class Connection
{
std::string db;
public:
Connection()
{
log_info("create connection");
}
explicit Connection(const std::string& db_)
: db(db_)
{
log_info("create connection to \"" << db << '"');
}
~Connection()
{
log_info("destroy connection");
}
void doSomething()
{
sleep(1);
}
};
// define a custom connector for passing the connection string
class Connector
{
std::string db;
public:
explicit Connector(const std::string& db_)
: db(db_)
{ }
Connection* operator() ()
{ return new Connection(db); }
};
// define a connection-pool-type
typedef cxxtools::Pool<Connection, Connector> ConnectionPoolType;
// define a thread, which fetches a connection from a pool
// and does something
class MyThread
{
cxxtools::AttachedThread thread;
ConnectionPoolType& pool;
unsigned threadNum;
unsigned sec;
public:
explicit MyThread (ConnectionPoolType& pool_, unsigned threadNum_, unsigned sec_ = 1)
: thread( cxxtools::callable(*this, &MyThread::run) ),
pool(pool_),
threadNum(threadNum_),
sec(sec_)
{ }
void create()
{ thread.start(); }
void join()
{ thread.join(); }
void run()
{
log_info("start thread " << threadNum);
sleep(sec);
// We fetch a object from the pool, and call a method pool.get() does
// not return a connection, but a proxy object, so we have to take
// care not to assign the object to a Connection, but use that proxy
// directy.
//
// This would be wrong:
// Connection conn = *pool.get(); // convert the proxy-object
// conn.doSomething(threadNum); // the connection is back in the pool here :-(
//
// The reason is, that the proxy object is destroyed too early.
// The proxy object puts the connection back to the free-list of the
// pool, before we use the connection.
//
log_info("doSomething in thread " << threadNum);
pool.get()->doSomething();
log_info("doSomething ends in thread " << threadNum);
log_info("thread ready " << threadNum);
}
};
int main(int argc, char* argv[])
{
try
{
log_init();
ConnectionPoolType connectionPool(3, Connector("mydb"));
MyThread th1(connectionPool, 1, 2);
MyThread th2(connectionPool, 2);
MyThread th3(connectionPool, 3, 3);
MyThread th4(connectionPool, 4, 3);
MyThread th5(connectionPool, 5, 4);
th1.create();
th2.create();
th3.create();
th4.create();
th5.create();
log_info("threads created");
th1.join();
// Thread 1 is ready and the connection is put back into the pool.
// We release all free connections here. At least one connection
// from thread 1 is released.
log_info("pool drop");
connectionPool.drop();
th2.join();
th4.join();
th3.join();
th5.join();
log_info("threads joined");
}
catch (const std::exception& e)
{
std::cerr << e.what() << std::endl;
}
}
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