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/**
* Copyright (c) 2012-2014 MongoDB 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.
*/
#include "mongo/pch.h"
#include "mongo/db/pipeline/pipeline_d.h"
#include "mongo/client/dbclientinterface.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/catalog/database.h"
#include "mongo/db/instance.h"
#include "mongo/db/pipeline/document_source.h"
#include "mongo/db/pipeline/pipeline.h"
#include "mongo/db/query/get_executor.h"
#include "mongo/db/query/query_planner.h"
#include "mongo/s/d_logic.h"
namespace mongo {
namespace {
class MongodImplementation : public DocumentSourceNeedsMongod::MongodInterface {
public:
MongodImplementation(const intrusive_ptr<ExpressionContext>& ctx)
: _ctx(ctx)
, _client(ctx->opCtx)
{}
DBClientBase* directClient() {
// opCtx may have changed since our last call
invariant(_ctx->opCtx);
_client.setOpCtx(_ctx->opCtx);
return &_client;
}
bool isSharded(const NamespaceString& ns) {
const ChunkVersion unsharded(0, 0, OID());
return !(shardingState.getVersion(ns.ns()).isWriteCompatibleWith(unsharded));
}
bool isCapped(const NamespaceString& ns) {
Client::ReadContext ctx(_ctx->opCtx, ns.ns());
Collection* collection = ctx.ctx().db()->getCollection(_ctx->opCtx, ns);
return collection && collection->isCapped();
}
private:
intrusive_ptr<ExpressionContext> _ctx;
DBDirectClient _client;
};
}
boost::shared_ptr<PlanExecutor> PipelineD::prepareCursorSource(
OperationContext* txn,
Collection* collection,
const intrusive_ptr<Pipeline>& pPipeline,
const intrusive_ptr<ExpressionContext>& pExpCtx) {
// get the full "namespace" name
const string& fullName = pExpCtx->ns.ns();
pExpCtx->opCtx->lockState()->assertAtLeastReadLocked(fullName);
// We will be modifying the source vector as we go
Pipeline::SourceContainer& sources = pPipeline->sources;
// Inject a MongodImplementation to sources that need them.
for (size_t i = 0; i < sources.size(); i++) {
DocumentSourceNeedsMongod* needsMongod =
dynamic_cast<DocumentSourceNeedsMongod*>(sources[i].get());
if (needsMongod) {
needsMongod->injectMongodInterface(
boost::make_shared<MongodImplementation>(pExpCtx));
}
}
if (!sources.empty() && sources.front()->isValidInitialSource()) {
if (dynamic_cast<DocumentSourceMergeCursors*>(sources.front().get())) {
// Enable the hooks for setting up authentication on the subsequent internal
// connections we are going to create. This would normally have been done
// when SetShardVersion was called, but since SetShardVersion is never called
// on secondaries, this is needed.
ShardedConnectionInfo::addHook();
}
return boost::shared_ptr<PlanExecutor>(); // don't need a cursor
}
// Look for an initial match. This works whether we got an initial query or not.
// If not, it results in a "{}" query, which will be what we want in that case.
const BSONObj queryObj = pPipeline->getInitialQuery();
if (!queryObj.isEmpty()) {
// This will get built in to the Cursor we'll create, so
// remove the match from the pipeline
sources.pop_front();
}
// Find the set of fields in the source documents depended on by this pipeline.
const DepsTracker deps = pPipeline->getDependencies(queryObj);
// Passing query an empty projection since it is faster to use ParsedDeps::extractFields().
// This will need to change to support covering indexes (SERVER-12015). There is an
// exception for textScore since that can only be retrieved by a query projection.
const BSONObj projectionForQuery = deps.needTextScore ? deps.toProjection() : BSONObj();
/*
Look for an initial sort; we'll try to add this to the
Cursor we create. If we're successful in doing that (further down),
we'll remove the $sort from the pipeline, because the documents
will already come sorted in the specified order as a result of the
index scan.
*/
intrusive_ptr<DocumentSourceSort> sortStage;
BSONObj sortObj;
if (!sources.empty()) {
sortStage = dynamic_cast<DocumentSourceSort*>(sources.front().get());
if (sortStage) {
// build the sort key
sortObj = sortStage->serializeSortKey(/*explain*/false).toBson();
}
}
// Create the PlanExecutor.
//
// If we try to create a PlanExecutor that includes both the match and the
// sort, and the two are incompatible wrt the available indexes, then
// we don't get a PlanExecutor back.
//
// So we try to use both first. If that fails, try again, without the
// sort.
//
// If we don't have a sort, jump straight to just creating a PlanExecutor.
// without the sort.
//
// If we are able to incorporate the sort into the PlanExecutor, remove it
// from the head of the pipeline.
//
// LATER - we should be able to find this out before we create the
// cursor. Either way, we can then apply other optimizations there
// are tickets for, such as SERVER-4507.
const size_t runnerOptions = QueryPlannerParams::DEFAULT
| QueryPlannerParams::INCLUDE_SHARD_FILTER
| QueryPlannerParams::NO_BLOCKING_SORT
;
boost::shared_ptr<PlanExecutor> exec;
bool sortInRunner = false;
const WhereCallbackReal whereCallback(pExpCtx->opCtx, pExpCtx->ns.db());
if (sortStage) {
CanonicalQuery* cq;
Status status =
CanonicalQuery::canonicalize(pExpCtx->ns,
queryObj,
sortObj,
projectionForQuery,
&cq,
whereCallback);
PlanExecutor* rawExec;
if (status.isOK() && getExecutor(txn, collection, cq, &rawExec, runnerOptions).isOK()) {
// success: The PlanExecutor will handle sorting for us using an index.
exec.reset(rawExec);
sortInRunner = true;
sources.pop_front();
if (sortStage->getLimitSrc()) {
// need to reinsert coalesced $limit after removing $sort
sources.push_front(sortStage->getLimitSrc());
}
}
}
if (!exec.get()) {
const BSONObj noSort;
CanonicalQuery* cq;
uassertStatusOK(
CanonicalQuery::canonicalize(pExpCtx->ns,
queryObj,
noSort,
projectionForQuery,
&cq,
whereCallback));
PlanExecutor* rawExec;
uassertStatusOK(getExecutor(txn, collection, cq, &rawExec, runnerOptions));
exec.reset(rawExec);
}
// DocumentSourceCursor expects a yielding PlanExecutor that has had its state saved.
exec->saveState();
// Put the PlanExecutor into a DocumentSourceCursor and add it to the front of the pipeline.
intrusive_ptr<DocumentSourceCursor> pSource =
DocumentSourceCursor::create(fullName, exec, pExpCtx);
// Note the query, sort, and projection for explain.
pSource->setQuery(queryObj);
if (sortInRunner)
pSource->setSort(sortObj);
pSource->setProjection(deps.toProjection(), deps.toParsedDeps());
while (!sources.empty() && pSource->coalesce(sources.front())) {
sources.pop_front();
}
pPipeline->addInitialSource(pSource);
return exec;
}
} // namespace mongo
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