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ConnectionPool.cpp
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ConnectionPool.cpp
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/* -*- C++ -*-; c-basic-offset: 4; indent-tabs-mode: nil */
/*
* Implementation for ConnectionPool class.
*
* Copyright (c) 2009 Webroot Software, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
#include "ConnectionPool.h"
#include <sstream>
#include <utility>
#include <boost/thread/locks.hpp>
#include <boost/thread/mutex.hpp>
namespace Voldemort {
using namespace boost;
using namespace std;
enum {
STATUS_UNINIT = 0,
STATUS_READY,
STATUS_CHECKED_OUT
};
ConnectionPool::ConnectionPool(shared_ptr<ClientConfig>& config)
: clientConfig(config), totalConnections(0) {
}
shared_ptr<Connection>& ConnectionPool::checkout(const string& host, int port,
const string& negString) {
stringstream hostKey;
hostKey << host << ":" << port;
shared_ptr<Connection>* connRet = NULL;
{
// Ensure that we don't have too many connections in the pool
unique_lock<mutex> lock(poolMutex);
host_entry_ptr& hep = pool[hostKey.str()];
int& host_ready_count = ready_count[hostKey.str()];
if (!hep.get()) {
hep = host_entry_ptr(new host_entry());
host_ready_count = 0;
}
while ((host_ready_count == 0) &&
(((clientConfig->getMaxConnectionsPerNode() > 0) &&
(hep->size() >= (size_t)clientConfig->getMaxConnectionsPerNode())) ||
((clientConfig->getMaxTotalConnections() > 0) &&
(totalConnections >= clientConfig->getMaxTotalConnections())))) {
checkinCond.wait(lock);
}
// Search for a ready connection to try
if (host_ready_count > 0) {
host_entry::iterator heit;
for (heit = hep->begin(); heit != hep->end(); ++heit) {
if (heit->second.first == STATUS_READY) {
heit->second.first = STATUS_CHECKED_OUT;
host_ready_count -= 1;
return heit->second.second;
}
}
}
// Otherwise fall back to creating a new connection
// Reserve a spot in the pool
stringstream portStr;
portStr << port;
std::string portString = portStr.str();
//cout << "Creating connection " << hostKey.str() << endl;
shared_ptr<Connection> conn(new Connection(host, portString, negString,
clientConfig));
(*hep)[(size_t)conn.get()] = make_pair((int)STATUS_UNINIT, conn);
totalConnections += 1;
connRet = &(((*hep)[(size_t)conn.get()]).second);
}
// Connect to the remote host
try {
(*connRet)->connect();
} catch (...) {
checkin(*connRet);
throw;
}
{
lock_guard<mutex> guard(poolMutex);
(*pool[hostKey.str()])[(size_t)connRet->get()].first =
(int)STATUS_CHECKED_OUT;
}
return *connRet;
}
void ConnectionPool::checkin(shared_ptr<Connection>& conn) {
string hostKey = conn->get_host() + ":" + conn->get_port();
// cout << "Checking in " << hostKey << endl;
{
lock_guard<mutex> guard(poolMutex);
host_entry_ptr& hep = pool[hostKey];
int& host_ready_count = ready_count[hostKey];
if (!hep.get()) {
hep = host_entry_ptr(new host_entry());
host_ready_count = 0;
}
conn_entry& ce = (*hep)[(size_t)conn.get()];
if (ce.first != STATUS_CHECKED_OUT || !conn->is_active()) {
/* Something horrible has happened to our connection */
hep->erase((size_t)conn.get());
totalConnections -= 1;
//cout << "Destroying connection " << hostKey << endl;
} else {
host_ready_count += 1;
ce.first = STATUS_READY;
}
}
checkinCond.notify_one();
}
} /* namespace Voldemort */