1 files changed, 225 insertions, 0 deletions
diff --git a/src/mongo/db/pipeline/pipeline.h b/src/mongo/db/pipeline/pipeline.h
new file mode 100755
index 00000000000..9f3a545c5d7
--- /dev/null
+++ b/src/mongo/db/pipeline/pipeline.h
@@ -0,0 +1,225 @@
+/**
+ * Copyright 2011 (c) 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/>.
+ */
+
+#pragma once
+
+#include "mongo/pch.h"
+
+#include "util/intrusive_counter.h"
+#include "util/timer.h"
+
+namespace mongo {
+    class BSONObj;
+    class BSONObjBuilder;
+    class BSONArrayBuilder;
+    class DocumentSource;
+    class DocumentSourceProject;
+    class Expression;
+    class ExpressionContext;
+    class ExpressionNary;
+    struct OpDesc; // local private struct
+
+    /** mongodb "commands" (sent via db.$cmd.findOne(...))
+        subclass to make a command.  define a singleton object for it.
+        */
+    class Pipeline :
+        public IntrusiveCounterUnsigned {
+    public:
+        virtual ~Pipeline();
+
+        /**
+          Create a pipeline from the command.
+
+          @param errmsg where to write errors, if there are any
+          @param cmdObj the command object sent from the client
+          @returns the pipeline, if created, otherwise a NULL reference
+         */
+        static intrusive_ptr<Pipeline> parseCommand(
+            string &errmsg, BSONObj &cmdObj,
+            const intrusive_ptr<ExpressionContext> &pCtx);
+
+        /**
+          Get the collection name from the command.
+
+          @returns the collection name
+        */
+        string getCollectionName() const;
+
+        /**
+          Split the current Pipeline into a Pipeline for each shard, and
+          a Pipeline that combines the results within mongos.
+
+          This permanently alters this pipeline for the merging operation.
+
+          @returns the Spec for the pipeline command that should be sent
+            to the shards
+        */
+        intrusive_ptr<Pipeline> splitForSharded();
+
+        /**
+           If the pipeline starts with a $match, dump its BSON predicate
+           specification to the supplied builder and return true.
+
+           @param pQueryBuilder the builder to put the match BSON into
+           @returns true if a match was found and dumped to pQueryBuilder,
+             false otherwise
+         */
+        bool getInitialQuery(BSONObjBuilder *pQueryBuilder) const;
+
+        /**
+          Write the Pipeline as a BSONObj command.  This should be the
+          inverse of parseCommand().
+
+          This is only intended to be used by the shard command obtained
+          from splitForSharded().  Some pipeline operations in the merge
+          process do not have equivalent command forms, and using this on
+          the mongos Pipeline will cause assertions.
+
+          @param the builder to write the command to
+        */
+        void toBson(BSONObjBuilder *pBuilder) const;
+
+        /**
+          Run the Pipeline on the given source.
+
+          @param result builder to write the result to
+          @param errmsg place to put error messages, if any
+          @param pSource the document source to use at the head of the chain
+          @returns true on success, false if an error occurs
+        */
+        bool run(BSONObjBuilder &result, string &errmsg,
+                 const intrusive_ptr<DocumentSource> &pSource);
+
+        /**
+          Debugging:  should the processing pipeline be split within
+          mongod, simulating the real mongos/mongod split?  This is determined
+          by setting the splitMongodPipeline field in an "aggregate"
+          command.
+
+          The split itself is handled by the caller, which is currently
+          pipeline_command.cpp.
+
+          @returns true if the pipeline is to be split
+         */
+        bool getSplitMongodPipeline() const;
+
+        /**
+           Ask if this is for an explain request.
+
+           @returns true if this is an explain
+         */
+        bool isExplain() const;
+
+        /**
+          The aggregation command name.
+         */
+        static const char commandName[];
+
+        /*
+          PipelineD is a "sister" class that has additional functionality
+          for the Pipeline.  It exists because of linkage requirements.
+          Pipeline needs to function in mongod and mongos.  PipelineD
+          contains extra functionality required in mongod, and which can't
+          appear in mongos because the required symbols are unavailable
+          for linking there.  Consider PipelineD to be an extension of this
+          class for mongod only.
+         */
+        friend class PipelineD;
+
+    private:
+        static const char pipelineName[];
+        static const char explainName[];
+        static const char fromRouterName[];
+        static const char splitMongodPipelineName[];
+        static const char serverPipelineName[];
+        static const char mongosPipelineName[];
+
+        Pipeline(const intrusive_ptr<ExpressionContext> &pCtx);
+
+        /*
+          Write the pipeline's operators to the given array, with the
+          explain flag true (for DocumentSource::addToBsonArray()).
+
+          @param pArrayBuilder where to write the ops to
+         */
+        void writeExplainOps(BSONArrayBuilder *pArrayBuilder) const;
+
+        /*
+          Write the pipeline's operators to the given result document,
+          for a shard server (or regular server, in an unsharded setup).
+
+          This uses writeExplainOps() and adds that array to the result
+          with the serverPipelineName.  That will be preceded by explain
+          information for the input source.
+
+          @param result the object to add the explain information to
+          @param pInputSource source for the pipeline
+         */
+        void writeExplainShard(BSONObjBuilder &result,
+            const intrusive_ptr<DocumentSource> &pInputSource) const;
+
+        /*
+          Write the pipeline's operators to the given result document,
+          for a mongos instance.
+
+          This first adds the serverPipeline obtained from the input
+          source.
+
+          Then this uses writeExplainOps() and adds that array to the result
+          with the serverPipelineName.  That will be preceded by explain
+          information for the input source.
+
+          @param result the object to add the explain information to
+          @param pInputSource source for the pipeline; expected to be the
+            output of a shard
+         */
+        void writeExplainMongos(BSONObjBuilder &result,
+            const intrusive_ptr<DocumentSource> &pInputSource) const;
+
+        string collectionName;
+        typedef vector<intrusive_ptr<DocumentSource> > SourceVector;
+        SourceVector sourceVector;
+        bool explain;
+
+        bool splitMongodPipeline;
+        intrusive_ptr<ExpressionContext> pCtx;
+    };
+
+} // namespace mongo
+
+
+/* ======================= INLINED IMPLEMENTATIONS ========================== */
+
+namespace mongo {
+
+    inline string Pipeline::getCollectionName() const {
+        return collectionName;
+    }
+
+    inline bool Pipeline::getSplitMongodPipeline() const {
+        if (!DEBUG_BUILD)
+            return false;
+
+        return splitMongodPipeline;
+    }
+
+    inline bool  Pipeline::isExplain() const {
+        return explain;
+    }
+
+} // namespace mongo
+
+