UpdateResult update(const UpdateRequest& request, OpDebug* opDebug) {
// Should the modifiers validate their embedded docs via okForStorage
// Only user updates should be checked. Any system or replication stuff should pass through.
// Config db docs shouldn't get checked for valid field names since the shard key can have
// a dot (".") in it.
bool shouldValidate = !(request.isFromReplication() ||
request.getNamespaceString().isConfigDB());
// TODO: Consider some sort of unification between the UpdateDriver, ModifierInterface
// and UpdateRequest structures.
UpdateDriver::Options opts;
opts.multi = request.isMulti();
opts.upsert = request.isUpsert();
opts.logOp = request.shouldUpdateOpLog();
opts.modOptions = ModifierInterface::Options( request.isFromReplication(), shouldValidate );
UpdateDriver driver( opts );
Status status = driver.parse( request.getUpdates() );
if ( !status.isOK() ) {
uasserted( 16840, status.reason() );
}
return update(request, opDebug, &driver);
}
UpdateResult update(const UpdateRequest& request, OpDebug* opDebug, UpdateDriver* driver) {
LOG(3) << "processing update : " << request;
const NamespaceString& nsString = request.getNamespaceString();
validateUpdate( nsString.ns().c_str(), request.getUpdates(), request.getQuery() );
NamespaceDetails* nsDetails = nsdetails( nsString.ns() );
NamespaceDetailsTransient* nsDetailsTransient =
&NamespaceDetailsTransient::get( nsString.ns().c_str() );
// TODO: This seems a bit circuitious.
opDebug->updateobj = request.getUpdates();
driver->refreshIndexKeys( nsDetailsTransient->indexKeys() );
shared_ptr<Cursor> cursor = getOptimizedCursor(
nsString.ns(), request.getQuery(), BSONObj(), request.getQueryPlanSelectionPolicy() );
// If the update was marked with '$isolated' (a.k.a '$atomic'), we are not allowed to
// yield while evaluating the update loop below.
//
// TODO: Old code checks this repeatedly within the update loop. Is that necessary? It seems
// that once atomic should be always atomic.
const bool isolated =
cursor->ok() &&
cursor->matcher() &&
cursor->matcher()->docMatcher().atomic();
// The 'cursor' the optimizer gave us may contain query plans that generate duplicate
// diskloc's. We set up here the mechanims that will prevent us from processing those
// twice if we see them. We also set up a 'ClientCursor' so that we can support
// yielding.
//
// TODO: Is it valid to call this on a non-ok cursor?
const bool dedupHere = cursor->autoDedup();
//
// We'll start assuming we have one or more documents for this update. (Othwerwise,
// we'll fallback to upserting.)
//
// We record that this will not be an upsert, in case a mod doesn't want to be applied
// when in strict update mode.
driver->setContext( ModifierInterface::ExecInfo::UPDATE_CONTEXT );
// Let's fetch each of them and pipe them through the update expression, making sure to
// keep track of the necessary stats. Recall that we'll be pulling documents out of
// cursors and some of them do not deduplicate the entries they generate. We have
// deduping logic in here, too -- for now.
unordered_set<DiskLoc, DiskLoc::Hasher> seenLocs;
int numMatched = 0;
// Reset these counters on each call. We might re-enter this function to retry this
// update if we throw a page fault exception below, and we rely on these counters
// reflecting only the actions taken locally. In particlar, we must have the no-op
// counter reset so that we can meaningfully comapre it with numMatched above.
opDebug->nscanned = 0;
opDebug->nupdateNoops = 0;
Client& client = cc();
mutablebson::Document doc;
mutablebson::DamageVector damages;
// If we are going to be yielding, we will need a ClientCursor scoped to this loop. We
// only loop as long as the underlying cursor is OK.
for ( auto_ptr<ClientCursor> clientCursor; cursor->ok(); ) {
// If we haven't constructed a ClientCursor, and if the client allows us to throw
// page faults, and if we are referring to a location that is likely not in
// physical memory, then throw a PageFaultException. The entire operation will be
// restarted.
if ( clientCursor.get() == NULL &&
client.allowedToThrowPageFaultException() &&
!cursor->currLoc().isNull() &&
!cursor->currLoc().rec()->likelyInPhysicalMemory() ) {
// We should never throw a PFE if we have already updated items. The numMatched
// variable includes no-ops, which do not prevent us from raising a PFE, so if
// numMatched is non-zero, we are still OK to throw as long all matched items
// resulted in a no-op.
dassert((numMatched == 0) || (numMatched == opDebug->nupdateNoops));
throw PageFaultException( cursor->currLoc().rec() );
}
if ( !isolated && opDebug->nscanned != 0 ) {
// We are permitted to yield. To do so we need a ClientCursor, so create one
// now if we have not yet done so.
if ( !clientCursor.get() )
clientCursor.reset(
new ClientCursor( QueryOption_NoCursorTimeout, cursor, nsString.ns() ) );
// Ask the client cursor to yield. We get two bits of state back: whether or not
// we yielded, and whether or not we correctly recovered from yielding.
bool yielded = false;
const bool recovered = clientCursor->yieldSometimes(
ClientCursor::WillNeed, &yielded );
if ( !recovered ) {
// If we failed to recover from the yield, then the ClientCursor is already
// gone. Release it so we don't destroy it a second time.
clientCursor.release();
break;
}
if ( !cursor->ok() ) {
// If the cursor died while we were yielded, just get out of the update loop.
break;
}
if ( yielded ) {
// We yielded and recovered OK, and our cursor is still good. Details about
// our namespace may have changed while we were yielded, so we re-acquire
// them here. If we can't do so, escape the update loop. Otherwise, refresh
// the driver so that it knows about what is currently indexed.
nsDetails = nsdetails( nsString.ns() );
if ( !nsDetails )
break;
nsDetailsTransient = &NamespaceDetailsTransient::get( nsString.ns().c_str() );
// TODO: This copies the index keys, but it may not need to do so.
driver->refreshIndexKeys( nsDetailsTransient->indexKeys() );
}
}
// Let's fetch the next candidate object for this update.
Record* record = cursor->_current();
DiskLoc loc = cursor->currLoc();
const BSONObj oldObj = loc.obj();
// We count how many documents we scanned even though we may skip those that are
// deemed duplicated. The final 'numUpdated' and 'nscanned' numbers may differ for
// that reason.
opDebug->nscanned++;
// Skips this document if it:
// a) doesn't match the query portion of the update
// b) was deemed duplicate by the underlying cursor machinery
//
// Now, if we are going to update the document,
// c) we don't want to do so while the cursor is at it, as that may invalidate
// the cursor. So, we advance to next document, before issuing the update.
MatchDetails matchDetails;
matchDetails.requestElemMatchKey();
if ( !cursor->currentMatches( &matchDetails ) ) {
// a)
cursor->advance();
continue;
}
else if ( cursor->getsetdup( loc ) && dedupHere ) {
// b)
cursor->advance();
continue;
}
else if (!driver->isDocReplacement() && request.isMulti()) {
// c)
cursor->advance();
if ( dedupHere ) {
if ( seenLocs.count( loc ) ) {
continue;
}
}
// There are certain kind of cursors that hold multiple pointers to data
// underneath. $or cursors is one example. In a $or cursor, it may be the case
// that when we did the last advance(), we finished consuming documents from
// one of $or child and started consuming the next one. In that case, it is
// possible that the last document of the previous child is the same as the
// first document of the next (see SERVER-5198 and jstests/orp.js).
//
// So we advance the cursor here until we see a new diskloc.
//
// Note that we won't be yielding, and we may not do so for a while if we find
// a particularly duplicated sequence of loc's. That is highly unlikely,
// though. (See SERVER-5725, if curious, but "stage" based $or will make that
// ticket moot).
while( cursor->ok() && loc == cursor->currLoc() ) {
cursor->advance();
}
}
// For some (unfortunate) historical reasons, not all cursors would be valid after
// a write simply because we advanced them to a document not affected by the write.
// To protect in those cases, not only we engaged in the advance() logic above, but
// we also tell the cursor we're about to write a document that we've just seen.
// prepareToTouchEarlierIterate() requires calling later
// recoverFromTouchingEarlierIterate(), so we make a note here to do so.
bool touchPreviousDoc = request.isMulti() && cursor->ok();
if ( touchPreviousDoc ) {
if ( clientCursor.get() )
clientCursor->setDoingDeletes( true );
cursor->prepareToTouchEarlierIterate();
}
// Found a matching document
numMatched++;
// Ask the driver to apply the mods. It may be that the driver can apply those "in
// place", that is, some values of the old document just get adjusted without any
// change to the binary layout on the bson layer. It may be that a whole new
// document is needed to accomodate the new bson layout of the resulting document.
doc.reset( oldObj, mutablebson::Document::kInPlaceEnabled );
BSONObj logObj;
// If there was a matched field, obtain it.
string matchedField;
if (matchDetails.hasElemMatchKey())
matchedField = matchDetails.elemMatchKey();
Status status = driver->update( matchedField, &doc, &logObj );
if ( !status.isOK() ) {
uasserted( 16837, status.reason() );
}
// If the driver applied the mods in place, we can ask the mutable for what
// changed. We call those changes "damages". :) We use the damages to inform the
// journal what was changed, and then apply them to the original document
// ourselves. If, however, the driver applied the mods out of place, we ask it to
// generate a new, modified document for us. In that case, the file manager will
// take care of the journaling details for us.
//
// This code flow is admittedly odd. But, right now, journaling is baked in the file
// manager. And if we aren't using the file manager, we have to do jounaling
// ourselves.
bool objectWasChanged = false;
BSONObj newObj;
const char* source = NULL;
bool inPlace = doc.getInPlaceUpdates(&damages, &source);
if ( inPlace && !driver->modsAffectIndices() ) {
// If a set of modifiers were all no-ops, we are still 'in place', but there is
// no work to do, in which case we want to consider the object unchanged.
if (!damages.empty() ) {
nsDetails->paddingFits();
// All updates were in place. Apply them via durability and writing pointer.
mutablebson::DamageVector::const_iterator where = damages.begin();
const mutablebson::DamageVector::const_iterator end = damages.end();
for( ; where != end; ++where ) {
const char* sourcePtr = source + where->sourceOffset;
void* targetPtr = getDur().writingPtr(
const_cast<char*>(oldObj.objdata()) + where->targetOffset,
where->size);
std::memcpy(targetPtr, sourcePtr, where->size);
}
objectWasChanged = true;
opDebug->fastmod = true;
}
newObj = oldObj;
}
else {
// The updates were not in place. Apply them through the file manager.
newObj = doc.getObject();
DiskLoc newLoc = theDataFileMgr.updateRecord(nsString.ns().c_str(),
nsDetails,
nsDetailsTransient,
record,
loc,
newObj.objdata(),
newObj.objsize(),
*opDebug);
// If we've moved this object to a new location, make sure we don't apply
// that update again if our traversal picks the objecta again.
//
// We also take note that the diskloc if the updates are affecting indices.
// Chances are that we're traversing one of them and they may be multi key and
// therefore duplicate disklocs.
if ( newLoc != loc || driver->modsAffectIndices() ) {
seenLocs.insert( newLoc );
}
objectWasChanged = true;
}
// Log Obj
if ( request.shouldUpdateOpLog() ) {
if ( driver->isDocReplacement() || !logObj.isEmpty() ) {
BSONObj idQuery = driver->makeOplogEntryQuery(newObj, request.isMulti());
logOp("u", nsString.ns().c_str(), logObj , &idQuery,
NULL, request.isFromMigration(), &newObj);
}
}
// If it was noop since the document didn't change, record that.
if (!objectWasChanged)
opDebug->nupdateNoops++;
if (!request.isMulti()) {
break;
}
// If we used the cursor mechanism that prepares an earlier seen document for a
// write we need to tell such mechanisms that the write is over.
if ( touchPreviousDoc ) {
cursor->recoverFromTouchingEarlierIterate();
}
getDur().commitIfNeeded();
}
// TODO: Can this be simplified?
if ((numMatched > 0) || (numMatched == 0 && !request.isUpsert()) ) {
opDebug->nupdated = numMatched;
return UpdateResult( numMatched > 0 /* updated existing object(s) */,
!driver->isDocReplacement() /* $mod or obj replacement */,
numMatched /* # of docments update, even no-ops */,
BSONObj() );
}
//
// We haven't found any existing document so an insert is done
// (upsert is true).
//
opDebug->upsert = true;
// Since this is an insert (no docs found and upsert:true), we will be logging it
// as an insert in the oplog. We don't need the driver's help to build the
// oplog record, then. We also set the context of the update driver to the INSERT_CONTEXT.
// Some mods may only work in that context (e.g. $setOnInsert).
driver->setLogOp( false );
driver->setContext( ModifierInterface::ExecInfo::INSERT_CONTEXT );
BSONObj baseObj;
// Reset the document we will be writing to
doc.reset( baseObj, mutablebson::Document::kInPlaceDisabled );
if ( request.getQuery().hasElement("_id") ) {
uassertStatusOK(doc.root().appendElement(request.getQuery().getField("_id")));
}
// If this is a $mod base update, we need to generate a document by examining the
// query and the mods. Otherwise, we can use the object replacement sent by the user
// update command that was parsed by the driver before.
// In the following block we handle the query part, and then do the regular mods after.
if ( *request.getUpdates().firstElementFieldName() == '$' ) {
uassertStatusOK(UpdateDriver::createFromQuery(request.getQuery(), doc));
opDebug->fastmodinsert = true;
}
// Apply the update modifications and then log the update as an insert manually.
Status status = driver->update( StringData(), &doc, NULL /* no oplog record */);
if ( !status.isOK() ) {
uasserted( 16836, status.reason() );
}
BSONObj newObj = doc.getObject();
theDataFileMgr.insertWithObjMod( nsString.ns().c_str(), newObj, false, request.isGod() );
if ( request.shouldUpdateOpLog() ) {
logOp( "i", nsString.ns().c_str(), newObj,
NULL, NULL, request.isFromMigration(), &newObj );
}
opDebug->nupdated = 1;
return UpdateResult( false /* updated a non existing document */,
!driver->isDocReplacement() /* $mod or obj replacement? */,
1 /* count of updated documents */,
newObj /* object that was upserted */ );
}