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// shardconnection.cpp
/**
* Copyright (C) 2008 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects
* for all of the code used other than as permitted herein. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you do not
* wish to do so, delete this exception statement from your version. If you
* delete this exception statement from all source files in the program,
* then also delete it in the license file.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kSharding
#define MONGO_PCH_WHITELISTED
#include "mongo/platform/basic.h"
#include "mongo/pch.h"
#undef MONGO_PCH_WHITELISTED
#include <boost/noncopyable.hpp>
#include <set>
#include "mongo/db/auth/authorization_manager.h"
#include "mongo/db/client.h"
#include "mongo/db/commands.h"
#include "mongo/db/lasterror.h"
#include "mongo/db/server_parameters.h"
#include "mongo/s/config.h"
#include "mongo/s/request.h"
#include "mongo/s/shard.h"
#include "mongo/s/stale_exception.h"
#include "mongo/s/version_manager.h"
#include "mongo/server.h"
#include "mongo/util/concurrency/spin_lock.h"
#include "mongo/util/exit.h"
#include "mongo/util/log.h"
#include "mongo/util/stacktrace.h"
namespace mongo {
DBConnectionPool shardConnectionPool;
class ClientConnections;
/**
* Class which tracks ClientConnections (the client connection pool) for each incoming
* connection, allowing stats access.
*/
class ActiveClientConnections {
public:
ActiveClientConnections() : _mutex( "ActiveClientConnections" ) {
}
void add( const ClientConnections* cc ) {
scoped_lock lock( _mutex );
_clientConnections.insert( cc );
}
void remove( const ClientConnections* cc ) {
scoped_lock lock( _mutex );
_clientConnections.erase( cc );
}
// Implemented after ClientConnections
void appendInfo( BSONObjBuilder& b );
private:
mongo::mutex _mutex;
set<const ClientConnections*> _clientConnections;
} activeClientConnections;
/**
* Command to allow access to the sharded conn pool information in mongos.
* TODO: Refactor with other connection pooling changes
*/
class ShardedPoolStats : public Command {
public:
ShardedPoolStats() : Command( "shardConnPoolStats" ) {}
virtual void help( stringstream &help ) const { help << "stats about the shard connection pool"; }
virtual bool isWriteCommandForConfigServer() const { return false; }
virtual bool slaveOk() const { return true; }
// Same privs as connPoolStats
virtual void addRequiredPrivileges( const std::string& dbname,
const BSONObj& cmdObj,
std::vector<Privilege>* out )
{
ActionSet actions;
actions.addAction( ActionType::connPoolStats );
out->push_back( Privilege( ResourcePattern::forClusterResource(), actions ) );
}
virtual bool run( OperationContext* txn, const string&, mongo::BSONObj&, int, std::string&, mongo::BSONObjBuilder& result, bool ) {
// Base pool info
shardConnectionPool.appendInfo( result );
// Thread connection info
activeClientConnections.appendInfo( result );
return true;
}
} shardedPoolStatsCmd;
/**
* holds all the actual db connections for a client to various servers
* 1 per thread, so doesn't have to be thread safe
*/
class ClientConnections : boost::noncopyable {
public:
struct Status : boost::noncopyable {
Status() : created(0), avail(0) {}
// May be read concurrently, but only written from
// this thread.
long long created;
DBClientBase* avail;
};
// Gets or creates the status object for the host
Status* _getStatus( const string& addr ) {
scoped_spinlock lock( _lock );
Status* &temp = _hosts[addr];
if ( ! temp )
temp = new Status();
return temp;
}
ClientConnections() {
// Start tracking client connections
activeClientConnections.add( this );
}
~ClientConnections() {
// Stop tracking these client connections
activeClientConnections.remove( this );
releaseAll( true );
}
void releaseAll( bool fromDestructor = false ) {
// Don't need spinlock protection because if not in the destructor, we don't
// modify _hosts, and if in the destructor we are not accessible to external
// threads.
for ( HostMap::iterator i=_hosts.begin(); i!=_hosts.end(); ++i ) {
string addr = i->first;
Status* ss = i->second;
verify( ss );
if ( ss->avail ) {
/* if we're shutting down, don't want to initiate release mechanism as it is slow,
and isn't needed since all connections will be closed anyway */
if ( inShutdown() ) {
if( versionManager.isVersionableCB( ss->avail ) ) versionManager.resetShardVersionCB( ss->avail );
delete ss->avail;
}
else
release( addr , ss->avail );
ss->avail = 0;
}
if ( fromDestructor ) delete ss;
}
if ( fromDestructor ) _hosts.clear();
}
DBClientBase * get( const string& addr , const string& ns ) {
{
// We want to report ns stats
scoped_spinlock lock(_lock);
if (ns.size() > 0)
_seenNS.insert(ns);
}
Status* s = _getStatus( addr );
auto_ptr<DBClientBase> c; // Handles cleanup if there's an exception thrown
if ( s->avail ) {
c.reset( s->avail );
s->avail = 0;
shardConnectionPool.onHandedOut( c.get() ); // May throw an exception
} else {
c.reset( shardConnectionPool.get( addr ) );
s->created++; // After, so failed creation doesn't get counted
}
return c.release();
}
void done( const string& addr , DBClientBase* conn ) {
Status* s = _hosts[addr];
verify( s );
const bool isConnGood = shardConnectionPool.isConnectionGood(addr, conn);
if (s->avail != NULL) {
warning() << "Detected additional sharded connection in the "
"thread local pool for " << addr << endl;
if (DBException::traceExceptions) {
// There shouldn't be more than one connection checked out to the same
// host on the same thread.
printStackTrace();
}
if (!isConnGood) {
delete s->avail;
s->avail = NULL;
}
// Let the internal pool handle the bad connection, this can also
// update the lower bounds for the known good socket creation time
// for this host.
release(addr, conn);
return;
}
if (!isConnGood) {
// Let the internal pool handle the bad connection.
release(addr, conn);
return;
}
// Note: Although we try our best to clear bad connections as much as possible,
// some of them can still slip through because of how ClientConnections are being
// used - as thread local variables. This means that threads won't be able to
// see the s->avail connection of other threads.
s->avail = conn;
}
void sync() {
for ( HostMap::iterator i=_hosts.begin(); i!=_hosts.end(); ++i ) {
string addr = i->first;
Status* ss = i->second;
if ( ss->avail )
ss->avail->getLastError();
}
}
void checkVersions( const string& ns ) {
vector<Shard> all;
Shard::getAllShards( all );
// Don't report exceptions here as errors in GetLastError
LastError::Disabled ignoreForGLE(lastError.get(false));
// Now only check top-level shard connections
for ( unsigned i=0; i<all.size(); i++ ) {
Shard& shard = all[i];
try {
string sconnString = shard.getConnString();
Status* s = _getStatus( sconnString );
if( ! s->avail ) {
s->avail = shardConnectionPool.get( sconnString );
s->created++; // After, so failed creation doesn't get counted
}
versionManager.checkShardVersionCB( s->avail, ns, false, 1 );
}
catch ( const DBException& ex ) {
warning() << "problem while initially checking shard versions on" << " "
<< shard.getName() << causedBy( ex ) << endl;
// NOTE: This is only a heuristic, to avoid multiple stale version retries
// across multiple shards, and does not affect correctness.
}
}
}
void release( const string& addr , DBClientBase * conn ) {
shardConnectionPool.release( addr , conn );
}
/**
* Appends info about the client connection pool to a BOBuilder
* Safe to call with activeClientConnections lock
*/
void appendInfo( BSONObjBuilder& b ) const {
scoped_spinlock lock( _lock );
BSONArrayBuilder hostsArrB( b.subarrayStart( "hosts" ) );
for ( HostMap::const_iterator i = _hosts.begin(); i != _hosts.end(); ++i ) {
BSONObjBuilder bb( hostsArrB.subobjStart() );
bb.append( "host", i->first );
bb.append( "created", i->second->created );
bb.appendBool( "avail", static_cast<bool>( i->second->avail ) );
bb.done();
}
hostsArrB.done();
BSONArrayBuilder nsArrB( b.subarrayStart( "seenNS" ) );
for ( set<string>::const_iterator i = _seenNS.begin(); i != _seenNS.end(); ++i ) {
nsArrB.append(*i);
}
nsArrB.done();
}
// Protects only the creation of new entries in the _hosts and _seenNS map
// from external threads. Reading _hosts / _seenNS in this thread doesn't
// need protection.
mutable SpinLock _lock;
typedef map<string,Status*,DBConnectionPool::serverNameCompare> HostMap;
HostMap _hosts;
set<string> _seenNS;
/**
* Clears the connections kept by this pool (ie, not including the global pool)
*/
void clearPool() {
for(HostMap::iterator iter = _hosts.begin(); iter != _hosts.end(); ++iter) {
if (iter->second->avail != NULL) {
delete iter->second->avail;
}
delete iter->second;
}
_hosts.clear();
}
void forgetNS( const string& ns ) {
scoped_spinlock lock( _lock );
_seenNS.erase( ns );
}
// -----
static thread_specific_ptr<ClientConnections> _perThread;
static ClientConnections* threadInstance() {
ClientConnections* cc = _perThread.get();
if ( ! cc ) {
cc = new ClientConnections();
_perThread.reset( cc );
}
return cc;
}
};
thread_specific_ptr<ClientConnections> ClientConnections::_perThread;
/**
* Appends info about all active client shard connections to a BOBuilder
*/
void ActiveClientConnections::appendInfo( BSONObjBuilder& b ) {
BSONArrayBuilder arr( 64 * 1024 ); // There may be quite a few threads
{
scoped_lock lock( _mutex );
for ( set<const ClientConnections*>::const_iterator i = _clientConnections.begin();
i != _clientConnections.end(); ++i )
{
BSONObjBuilder bb( arr.subobjStart() );
(*i)->appendInfo( bb );
bb.done();
}
}
b.appendArray( "threads", arr.obj() );
}
ShardConnection::ShardConnection( const Shard * s , const string& ns, ChunkManagerPtr manager )
: _addr( s->getConnString() ) , _ns( ns ), _manager( manager ) {
_init();
}
ShardConnection::ShardConnection( const Shard& s , const string& ns, ChunkManagerPtr manager )
: _addr( s.getConnString() ) , _ns( ns ), _manager( manager ) {
_init();
}
ShardConnection::ShardConnection( const string& addr , const string& ns, ChunkManagerPtr manager )
: _addr( addr ) , _ns( ns ), _manager( manager ) {
_init();
}
void usingAShardConnection( const string& addr );
void ShardConnection::_init() {
verify( _addr.size() );
_conn = ClientConnections::threadInstance()->get( _addr , _ns );
_finishedInit = false;
usingAShardConnection( _addr );
}
void ShardConnection::_finishInit() {
if ( _finishedInit )
return;
_finishedInit = true;
if (versionManager.isVersionableCB(_conn)) {
// Make sure we specified a manager for the correct namespace
if (_ns.size() && _manager)
verify(_manager->getns() == _ns);
_setVersion = versionManager.checkShardVersionCB( this , false , 1 );
}
else {
// Make sure we didn't specify a manager for a non-versionable connection (i.e. config)
verify(!_manager);
_setVersion = false;
}
}
void ShardConnection::done() {
if ( _conn ) {
ClientConnections::threadInstance()->done( _addr , _conn );
_conn = 0;
_finishedInit = true;
}
}
void ShardConnection::kill() {
if ( _conn ) {
if( versionManager.isVersionableCB( _conn ) ) versionManager.resetShardVersionCB( _conn );
if (_conn->isFailed()) {
// Let the pool know about the bad connection and also delegate disposal to it.
ClientConnections::threadInstance()->done(_addr, _conn);
}
else {
delete _conn;
}
_conn = 0;
_finishedInit = true;
}
}
void ShardConnection::sync() {
ClientConnections::threadInstance()->sync();
}
void ShardConnection::checkMyConnectionVersions( const string & ns ) {
ClientConnections::threadInstance()->checkVersions( ns );
}
ShardConnection::~ShardConnection() {
if ( _conn ) {
if (_conn->isFailed()) {
if (_conn->getSockCreationMicroSec() ==
DBClientBase::INVALID_SOCK_CREATION_TIME) {
kill();
}
else {
// The pool takes care of deleting the failed connection - this
// will also trigger disposal of older connections in the pool
done();
}
}
else {
/* see done() comments above for why we log this line */
log() << "sharded connection to " << _conn->getServerAddress()
<< " not being returned to the pool" << endl;
kill();
}
}
}
void ShardConnection::releaseMyConnections() {
ClientConnections::threadInstance()->releaseAll();
}
void ShardConnection::clearPool() {
shardConnectionPool.clear();
ClientConnections::threadInstance()->clearPool();
}
void ShardConnection::forgetNS( const string& ns ) {
ClientConnections::threadInstance()->forgetNS( ns );
}
}
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