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121 lines
3.6 KiB
C++
121 lines
3.6 KiB
C++
/** @file connpool.h */
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/**
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* Copyright (C) 2008 10gen Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License, version 3,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include <stack>
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#include "dbclient.h"
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namespace mongo {
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struct PoolForHost {
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std::stack<DBClientBase*> pool;
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};
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/** Database connection pool.
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Generally, use ScopedDbConnection and do not call these directly.
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This class, so far, is suitable for use with unauthenticated connections.
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Support for authenticated connections requires some adjustements: please
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request...
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Usage:
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{
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ScopedDbConnection c("myserver");
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c.conn()...
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}
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*/
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class DBConnectionPool {
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boost::mutex poolMutex;
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map<string,PoolForHost*> pools; // servername -> pool
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public:
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void flush();
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DBClientBase *get(const string& host);
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void release(const string& host, DBClientBase *c) {
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boostlock L(poolMutex);
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pools[host]->pool.push(c);
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}
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};
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extern DBConnectionPool pool;
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/** Use to get a connection from the pool. On exceptions things
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clean up nicely.
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*/
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class ScopedDbConnection {
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const string host;
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DBClientBase *_conn;
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public:
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/** get the associated connection object */
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DBClientBase* operator->(){
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uassert( "did you call done already" , _conn );
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return _conn;
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}
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/** get the associated connection object */
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DBClientBase& conn() {
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uassert( "did you call done already" , _conn );
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return *_conn;
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}
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/** throws UserException if can't connect */
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ScopedDbConnection(const string& _host) :
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host(_host), _conn( pool.get(_host) ) {
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//cout << " for: " << _host << " got conn: " << _conn << endl;
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}
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/** Force closure of the connection. You should call this if you leave it in
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a bad state. Destructor will do this too, but it is verbose.
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*/
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void kill() {
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delete _conn;
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_conn = 0;
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}
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/** Call this when you are done with the connection.
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If you do not call done() before this object goes out of scope,
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we can't be sure we fully read all expected data of a reply on the socket. so
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we don't try to reuse the connection in that situation.
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*/
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void done() {
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if ( ! _conn )
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return;
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/* we could do this, but instead of assume one is using autoreconnect mode on the connection
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if ( _conn->isFailed() )
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kill();
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else
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*/
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pool.release(host, _conn);
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_conn = 0;
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}
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~ScopedDbConnection() {
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if ( _conn ) {
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/* see done() comments above for why we log this line */
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out() << "~ScopedDBConnection: _conn != null\n";
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kill();
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}
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}
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};
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} // namespace mongo
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