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mongodb/db/clientcursor.cpp

279 lines
9.1 KiB
C++

/**
* 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/>.
*/
/* clientcursor.cpp
ClientCursor is a wrapper that represents a cursorid from our database
application's perspective.
Cursor -- and its derived classes -- are our internal cursors.
*/
#include "stdafx.h"
#include "query.h"
#include "introspect.h"
#include <time.h>
#include "db.h"
#include "commands.h"
namespace mongo {
CCById ClientCursor::clientCursorsById;
CCByLoc ClientCursor::byLoc;
boost::recursive_mutex ClientCursor::ccmutex;
unsigned ClientCursor::byLocSize() {
recursive_boostlock lock(ccmutex);
return byLoc.size();
}
void ClientCursor::setLastLoc_inlock(DiskLoc L) {
if ( L == _lastLoc )
return;
if ( !_lastLoc.isNull() ) {
CCByLoc::iterator i = kv_find(byLoc, _lastLoc, this);
if ( i != byLoc.end() )
byLoc.erase(i);
}
if ( !L.isNull() )
byLoc.insert( make_pair(L, this) );
_lastLoc = L;
}
/* ------------------------------------------- */
/* must call this when a btree node is updated */
//void removedKey(const DiskLoc& btreeLoc, int keyPos) {
//}
/* todo: this implementation is incomplete. we use it as a prefix for dropDatabase, which
works fine as the prefix will end with '.'. however, when used with drop and
deleteIndexes, this could take out cursors that belong to something else -- if you
drop "foo", currently, this will kill cursors for "foobar".
*/
void ClientCursor::invalidate(const char *nsPrefix) {
vector<ClientCursor*> toDelete;
int len = strlen(nsPrefix);
assert( len > 0 && strchr(nsPrefix, '.') );
{
recursive_boostlock lock(ccmutex);
for ( CCByLoc::iterator i = byLoc.begin(); i != byLoc.end(); ++i ) {
ClientCursor *cc = i->second;
if ( strncmp(nsPrefix, cc->ns.c_str(), len) == 0 )
toDelete.push_back(i->second);
}
for ( vector<ClientCursor*>::iterator i = toDelete.begin(); i != toDelete.end(); ++i )
delete (*i);
}
}
/* called every 4 seconds. millis is amount of idle time passed since the last call -- could be zero */
void ClientCursor::idleTimeReport(unsigned millis) {
recursive_boostlock lock(ccmutex);
for ( CCByLoc::iterator i = byLoc.begin(); i != byLoc.end(); ) {
CCByLoc::iterator j = i;
i++;
if( j->second->shouldTimeout( millis ) ){
log(1) << "killing old cursor " << j->second->cursorid << ' ' << j->second->ns
<< " idle:" << j->second->idleTime() << "ms\n";
delete j->second;
}
}
}
/* must call when a btree bucket going away.
note this is potentially slow
*/
void ClientCursor::informAboutToDeleteBucket(const DiskLoc& b) {
recursive_boostlock lock(ccmutex);
RARELY if ( byLoc.size() > 70 ) {
log() << "perf warning: byLoc.size=" << byLoc.size() << " in aboutToDeleteBucket\n";
}
for ( CCByLoc::iterator i = byLoc.begin(); i != byLoc.end(); i++ )
i->second->c->aboutToDeleteBucket(b);
}
void aboutToDeleteBucket(const DiskLoc& b) {
ClientCursor::informAboutToDeleteBucket(b);
}
/* must call this on a delete so we clean up the cursors. */
void ClientCursor::aboutToDelete(const DiskLoc& dl) {
recursive_boostlock lock(ccmutex);
CCByLoc::iterator j = byLoc.lower_bound(dl);
CCByLoc::iterator stop = byLoc.upper_bound(dl);
if ( j == stop )
return;
vector<ClientCursor*> toAdvance;
while ( 1 ) {
toAdvance.push_back(j->second);
WIN assert( j->first == dl );
++j;
if ( j == stop )
break;
}
wassert( toAdvance.size() < 5000 );
for ( vector<ClientCursor*>::iterator i = toAdvance.begin(); i != toAdvance.end(); ++i ){
ClientCursor* cc = *i;
if ( cc->_doingDeletes ) continue;
Cursor *c = cc->c.get();
if ( c->capped() ){
delete cc;
continue;
}
c->checkLocation();
DiskLoc tmp1 = c->refLoc();
if ( tmp1 != dl ) {
/* this might indicate a failure to call ClientCursor::updateLocation() */
problem() << "warning: cursor loc " << tmp1 << " does not match byLoc position " << dl << " !" << endl;
}
c->advance();
if ( c->eof() ) {
// advanced to end -- delete cursor
delete cc;
}
else {
wassert( c->refLoc() != dl );
cc->updateLocation();
}
}
}
void aboutToDelete(const DiskLoc& dl) { ClientCursor::aboutToDelete(dl); }
ClientCursor::~ClientCursor() {
assert( pos != -2 );
{
recursive_boostlock lock(ccmutex);
setLastLoc_inlock( DiskLoc() ); // removes us from bylocation multimap
clientCursorsById.erase(cursorid);
// defensive:
(CursorId&) cursorid = -1;
pos = -2;
}
}
/* call when cursor's location changes so that we can update the
cursorsbylocation map. if you are locked and internally iterating, only
need to call when you are ready to "unlock".
*/
void ClientCursor::updateLocation() {
assert( cursorid );
_idleAgeMillis = 0;
DiskLoc cl = c->refLoc();
if ( lastLoc() == cl ) {
//log() << "info: lastloc==curloc " << ns << '\n';
return;
}
{
recursive_boostlock lock(ccmutex);
setLastLoc_inlock(cl);
c->noteLocation();
}
}
bool ClientCursor::yield() {
// need to store on the stack in case this gets deleted
CursorId id = cursorid;
bool doingDeletes = _doingDeletes;
_doingDeletes = false;
updateLocation();
{
/* a quick test that our temprelease is safe.
todo: make a YieldingCursor class
and then make the following code part of a unit test.
*/
const int test = 0;
static bool inEmpty = false;
if( test && !inEmpty ) {
inEmpty = true;
log() << "TEST: manipulate collection during remove" << endl;
if( test == 1 )
Helpers::emptyCollection(ns.c_str());
else if( test == 2 ) {
BSONObjBuilder b; string m;
dropCollection(ns.c_str(), m, b);
}
else {
dropDatabase(ns.c_str());
}
}
}
{
dbtempreleasecond unlock;
}
if ( ClientCursor::find( id , false ) == 0 ){
// i was deleted
return false;
}
_doingDeletes = doingDeletes;
return true;
}
int ctmLast = 0; // so we don't have to do find() which is a little slow very often.
long long ClientCursor::allocCursorId_inlock() {
long long x;
int ctm = (int) curTimeMillis();
while ( 1 ) {
x = (((long long)rand()) << 32);
x = x | ctm | 0x80000000; // OR to make sure not zero
if ( ctm != ctmLast || ClientCursor::find_inlock(x, false) == 0 )
break;
}
ctmLast = ctm;
DEV out() << " alloccursorid " << x << endl;
return x;
}
// QUESTION: Restrict to the namespace from which this command was issued?
// Alternatively, make this command admin-only?
class CmdCursorInfo : public Command {
public:
CmdCursorInfo() : Command( "cursorInfo" ) {}
virtual bool slaveOk() { return true; }
virtual void help( stringstream& help ) const {
help << " example: { cursorInfo : 1 }";
}
bool run(const char *dbname, BSONObj& jsobj, string& errmsg, BSONObjBuilder& result, bool fromRepl ){
recursive_boostlock lock(ClientCursor::ccmutex);
result.append("byLocation_size", unsigned( ClientCursor::byLoc.size() ) );
result.append("clientCursors_size", unsigned( ClientCursor::clientCursorsById.size() ) );
return true;
}
} cmdCursorInfo;
} // namespace mongo