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/**
* Copyright (C) 2010 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/>.
*/
#include "pch.h"
#include "../commands.h"
#include "rs.h"
#include "multicmd.h"
namespace mongo {
class CmdReplSetFresh : public ReplSetCommand {
public:
CmdReplSetFresh() : ReplSetCommand("replSetFresh") { }
private:
virtual bool run(const string& , BSONObj& cmdObj, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
if( !check(errmsg, result) )
return false;
if( cmdObj["set"].String() != theReplSet->name() ) {
errmsg = "wrong repl set name";
return false;
}
string who = cmdObj["who"].String();
int cfgver = cmdObj["cfgver"].Int();
OpTime opTime(cmdObj["opTime"].Date());
bool weAreFresher = false;
if( theReplSet->config().version > cfgver ) {
log() << "replSet member " << who << " is not yet aware its cfg version " << cfgver << " is stale" << rsLog;
result.append("info", "config version stale");
weAreFresher = true;
}
else if( opTime < theReplSet->lastOpTimeWritten ) {
weAreFresher = true;
}
result.appendDate("opTime", theReplSet->lastOpTimeWritten.asDate());
result.append("fresher", weAreFresher);
return true;
}
} cmdReplSetFresh;
class CmdReplSetElect : public ReplSetCommand {
public:
CmdReplSetElect() : ReplSetCommand("replSetElect") { }
private:
virtual bool run(const string& , BSONObj& cmdObj, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
if( !check(errmsg, result) )
return false;
//task::lam f = boost::bind(&Consensus::electCmdReceived, &theReplSet->elect, cmdObj, &result);
//theReplSet->mgr->call(f);
theReplSet->elect.electCmdReceived(cmdObj, &result);
return true;
}
} cmdReplSetElect;
int Consensus::totalVotes() const {
static int complain = 0;
int vTot = rs._self->config().votes;
for( Member *m = rs.head(); m; m=m->next() )
vTot += m->config().votes;
if( vTot % 2 == 0 && vTot && complain++ == 0 )
log() << "replSet " /*buildbot! warning */ "total number of votes is even - add arbiter or give one member an extra vote" << rsLog;
return vTot;
}
bool Consensus::aMajoritySeemsToBeUp() const {
int vUp = rs._self->config().votes;
for( Member *m = rs.head(); m; m=m->next() )
vUp += m->hbinfo().up() ? m->config().votes : 0;
return vUp * 2 > totalVotes();
}
bool Consensus::shouldRelinquish() const {
int vUp = rs._self->config().votes;
const long long T = rs.config().ho.heartbeatTimeoutMillis * rs.config().ho.heartbeatConnRetries;
for( Member *m = rs.head(); m; m=m->next() ) {
long long dt = m->hbinfo().timeDown();
if( dt < T )
vUp += m->config().votes;
}
return !( vUp * 2 > totalVotes() );
}
static const int VETO = -10000;
const time_t LeaseTime = 30;
unsigned Consensus::yea(unsigned memberId) /* throws VoteException */ {
Atomic<LastYea>::tran t(ly);
LastYea &ly = t.ref();
time_t now = time(0);
if( ly.when + LeaseTime >= now && ly.who != memberId ) {
log(1) << "replSet not voting yea for " << memberId <<
" voted for " << ly.who << ' ' << now-ly.when << " secs ago" << rsLog;
throw VoteException();
}
ly.when = now;
ly.who = memberId;
return rs._self->config().votes;
}
/* we vote for ourself at start of election. once it fails, we can cancel the lease we had in
place instead of leaving it for a long time.
*/
void Consensus::electionFailed(unsigned meid) {
Atomic<LastYea>::tran t(ly);
LastYea &L = t.ref();
DEV assert( L.who == meid ); // this may not always always hold, so be aware, but adding for now as a quick sanity test
if( L.who == meid )
L.when = 0;
}
/* todo: threading **************** !!!!!!!!!!!!!!!! */
void Consensus::electCmdReceived(BSONObj cmd, BSONObjBuilder* _b) {
BSONObjBuilder& b = *_b;
DEV log() << "replSet received elect msg " << cmd.toString() << rsLog;
else log(2) << "replSet received elect msg " << cmd.toString() << rsLog;
string set = cmd["set"].String();
unsigned whoid = cmd["whoid"].Int();
int cfgver = cmd["cfgver"].Int();
OID round = cmd["round"].OID();
int myver = rs.config().version;
const Member* primary = rs.box.getPrimary();
const Member* hopeful = rs.findById(whoid);
int vote = 0;
if( set != rs.name() ) {
log() << "replSet error received an elect request for '" << set << "' but our set name is '" << rs.name() << "'" << rsLog;
}
else if( myver < cfgver ) {
// we are stale. don't vote
}
else if( myver > cfgver ) {
// they are stale!
log() << "replSet info got stale version # during election" << rsLog;
vote = -10000;
}
else if( !hopeful ) {
log() << "couldn't find member with id " << whoid << rsLog;
vote = -10000;
}
else if( primary && primary->hbinfo().opTime > hopeful->hbinfo().opTime ) {
// other members might be aware of more up-to-date nodes
log() << hopeful->fullName() << " is trying to elect itself but " <<
primary->fullName() << " is already primary and more up-to-date" << rsLog;
vote = -10000;
}
else {
try {
vote = yea(whoid);
rs.relinquish();
log() << "replSet info voting yea for " << whoid << rsLog;
}
catch(VoteException&) {
log() << "replSet voting no already voted for another" << rsLog;
}
}
b.append("vote", vote);
b.append("round", round);
}
void ReplSetImpl::_getTargets(list<Target>& L, int& configVersion) {
configVersion = config().version;
for( Member *m = head(); m; m=m->next() )
if( m->hbinfo().up() )
L.push_back( Target(m->fullName()) );
}
/* config version is returned as it is ok to use this unlocked. BUT, if unlocked, you would need
to check later that the config didn't change. */
void ReplSetImpl::getTargets(list<Target>& L, int& configVersion) {
if( lockedByMe() ) {
_getTargets(L, configVersion);
return;
}
lock lk(this);
_getTargets(L, configVersion);
}
/* Do we have the newest data of them all?
@param allUp - set to true if all members are up. Only set if true returned.
@return true if we are freshest. Note we may tie.
*/
bool Consensus::weAreFreshest(bool& allUp, int& nTies) {
const OpTime ord = theReplSet->lastOpTimeWritten;
nTies = 0;
assert( !ord.isNull() );
BSONObj cmd = BSON(
"replSetFresh" << 1 <<
"set" << rs.name() <<
"opTime" << Date_t(ord.asDate()) <<
"who" << rs._self->fullName() <<
"cfgver" << rs._cfg->version );
list<Target> L;
int ver;
rs.getTargets(L, ver);
multiCommand(cmd, L);
int nok = 0;
allUp = true;
for( list<Target>::iterator i = L.begin(); i != L.end(); i++ ) {
if( i->ok ) {
nok++;
if( i->result["fresher"].trueValue() )
return false;
OpTime remoteOrd( i->result["opTime"].Date() );
if( remoteOrd == ord )
nTies++;
assert( remoteOrd <= ord );
}
else {
DEV log() << "replSet freshest returns " << i->result.toString() << rsLog;
allUp = false;
}
}
DEV log() << "replSet dev we are freshest of up nodes, nok:" << nok << " nTies:" << nTies << rsLog;
assert( ord <= theReplSet->lastOpTimeWritten ); // <= as this may change while we are working...
return true;
}
extern time_t started;
void Consensus::multiCommand(BSONObj cmd, list<Target>& L) {
assert( !rs.lockedByMe() );
mongo::multiCommand(cmd, L);
}
void Consensus::_electSelf() {
if( time(0) < steppedDown )
return;
{
const OpTime ord = theReplSet->lastOpTimeWritten;
if( ord == 0 ) {
log() << "replSet info not trying to elect self, do not yet have a complete set of data from any point in time" << rsLog;
return;
}
}
bool allUp;
int nTies;
if( !weAreFreshest(allUp, nTies) ) {
log() << "replSet info not electing self, we are not freshest" << rsLog;
return;
}
rs.sethbmsg("",9);
if( !allUp && time(0) - started < 60 * 5 ) {
/* the idea here is that if a bunch of nodes bounce all at once, we don't want to drop data
if we don't have to -- we'd rather be offline and wait a little longer instead
todo: make this configurable.
*/
rs.sethbmsg("not electing self, not all members up and we have been up less than 5 minutes");
return;
}
Member& me = *rs._self;
if( nTies ) {
/* tie? we then randomly sleep to try to not collide on our voting. */
/* todo: smarter. */
if( me.id() == 0 || sleptLast ) {
// would be fine for one node not to sleep
// todo: biggest / highest priority nodes should be the ones that get to not sleep
} else {
assert( !rs.lockedByMe() ); // bad to go to sleep locked
unsigned ms = ((unsigned) rand()) % 1000 + 50;
DEV log() << "replSet tie " << nTies << " sleeping a little " << ms << "ms" << rsLog;
sleptLast = true;
sleepmillis(ms);
throw RetryAfterSleepException();
}
}
sleptLast = false;
time_t start = time(0);
unsigned meid = me.id();
int tally = yea( meid );
bool success = false;
try {
log() << "replSet info electSelf " << meid << rsLog;
BSONObj electCmd = BSON(
"replSetElect" << 1 <<
"set" << rs.name() <<
"who" << me.fullName() <<
"whoid" << me.hbinfo().id() <<
"cfgver" << rs._cfg->version <<
"round" << OID::gen() /* this is just for diagnostics */
);
int configVersion;
list<Target> L;
rs.getTargets(L, configVersion);
multiCommand(electCmd, L);
{
RSBase::lock lk(&rs);
for( list<Target>::iterator i = L.begin(); i != L.end(); i++ ) {
DEV log() << "replSet elect res: " << i->result.toString() << rsLog;
if( i->ok ) {
int v = i->result["vote"].Int();
tally += v;
}
}
if( tally*2 <= totalVotes() ) {
log() << "replSet couldn't elect self, only received " << tally << " votes" << rsLog;
}
else if( time(0) - start > 30 ) {
// defensive; should never happen as we have timeouts on connection and operation for our conn
log() << "replSet too much time passed during our election, ignoring result" << rsLog;
}
else if( configVersion != rs.config().version ) {
log() << "replSet config version changed during our election, ignoring result" << rsLog;
}
else {
/* succeeded. */
log(1) << "replSet election succeeded, assuming primary role" << rsLog;
success = true;
rs.assumePrimary();
}
}
} catch( std::exception& ) {
if( !success ) electionFailed(meid);
throw;
}
if( !success ) electionFailed(meid);
}
void Consensus::electSelf() {
assert( !rs.lockedByMe() );
assert( !rs.myConfig().arbiterOnly );
assert( rs.myConfig().slaveDelay == 0 );
try {
_electSelf();
}
catch(RetryAfterSleepException&) {
throw;
}
catch(VoteException& ) {
log() << "replSet not trying to elect self as responded yea to someone else recently" << rsLog;
}
catch(DBException& e) {
log() << "replSet warning caught unexpected exception in electSelf() " << e.toString() << rsLog;
}
catch(...) {
log() << "replSet warning caught unexpected exception in electSelf()" << rsLog;
}
}
}
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