SERVER-19500 Cleanup explain logic

No functional changes, just moving code around.

1 files changed, 240 insertions, 0 deletions

diff --git a/src/mongo/db/commands/group_cmd.cpp b/src/mongo/db/commands/group_cmd.cpp
new file mode 100644
index 00000000000..1fd20f39a6f
--- /dev/null
+++ b/src/mongo/db/commands/group_cmd.cpp
@@ -0,0 +1,240 @@
+/**
+ *    Copyright (C) 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/platform/basic.h"
+
+#include "mongo/db/auth/action_set.h"
+#include "mongo/db/auth/action_type.h"
+#include "mongo/db/auth/authorization_session.h"
+#include "mongo/db/auth/privilege.h"
+#include "mongo/db/commands.h"
+#include "mongo/db/db_raii.h"
+#include "mongo/db/exec/group.h"
+#include "mongo/db/exec/working_set_common.h"
+#include "mongo/db/query/get_executor.h"
+
+namespace mongo {
+
+using std::unique_ptr;
+using std::string;
+
+namespace {
+
+class GroupCommand : public Command {
+public:
+    GroupCommand() : Command("group") {}
+
+private:
+    virtual bool isWriteCommandForConfigServer() const {
+        return false;
+    }
+
+    virtual bool maintenanceOk() const {
+        return false;
+    }
+
+    virtual bool slaveOk() const {
+        return false;
+    }
+
+    virtual bool slaveOverrideOk() const {
+        return true;
+    }
+
+    bool supportsReadConcern() const final {
+        return true;
+    }
+
+    virtual void help(std::stringstream& help) const {
+        help << "http://dochub.mongodb.org/core/aggregation";
+    }
+
+    virtual Status checkAuthForCommand(ClientBasic* client,
+                                       const std::string& dbname,
+                                       const BSONObj& cmdObj) {
+        std::string ns = parseNs(dbname, cmdObj);
+        if (!AuthorizationSession::get(client)
+                 ->isAuthorizedForActionsOnNamespace(NamespaceString(ns), ActionType::find)) {
+            return Status(ErrorCodes::Unauthorized, "unauthorized");
+        }
+        return Status::OK();
+    }
+
+    virtual std::string parseNs(const std::string& dbname, const BSONObj& cmdObj) const {
+        const BSONObj& p = cmdObj.firstElement().embeddedObjectUserCheck();
+        uassert(17211, "ns has to be set", p["ns"].type() == String);
+        return dbname + "." + p["ns"].String();
+    }
+
+    virtual Status explain(OperationContext* txn,
+                           const std::string& dbname,
+                           const BSONObj& cmdObj,
+                           ExplainCommon::Verbosity verbosity,
+                           BSONObjBuilder* out) const {
+        GroupRequest groupRequest;
+        Status parseRequestStatus = _parseRequest(dbname, cmdObj, &groupRequest);
+        if (!parseRequestStatus.isOK()) {
+            return parseRequestStatus;
+        }
+
+        groupRequest.explain = true;
+
+        AutoGetCollectionForRead ctx(txn, groupRequest.ns);
+        Collection* coll = ctx.getCollection();
+
+        auto statusWithPlanExecutor =
+            getExecutorGroup(txn, coll, groupRequest, PlanExecutor::YIELD_AUTO);
+        if (!statusWithPlanExecutor.isOK()) {
+            return statusWithPlanExecutor.getStatus();
+        }
+
+        unique_ptr<PlanExecutor> planExecutor = std::move(statusWithPlanExecutor.getValue());
+
+        Explain::explainStages(planExecutor.get(), verbosity, out);
+        return Status::OK();
+    }
+
+    virtual bool run(OperationContext* txn,
+                     const std::string& dbname,
+                     BSONObj& cmdObj,
+                     int options,
+                     std::string& errmsg,
+                     BSONObjBuilder& result) {
+        GroupRequest groupRequest;
+        Status parseRequestStatus = _parseRequest(dbname, cmdObj, &groupRequest);
+        if (!parseRequestStatus.isOK()) {
+            return appendCommandStatus(result, parseRequestStatus);
+        }
+
+        AutoGetCollectionForRead ctx(txn, groupRequest.ns);
+        Collection* coll = ctx.getCollection();
+
+        auto statusWithPlanExecutor =
+            getExecutorGroup(txn, coll, groupRequest, PlanExecutor::YIELD_AUTO);
+        if (!statusWithPlanExecutor.isOK()) {
+            return appendCommandStatus(result, statusWithPlanExecutor.getStatus());
+        }
+
+        unique_ptr<PlanExecutor> planExecutor = std::move(statusWithPlanExecutor.getValue());
+
+        // Group executors return ADVANCED exactly once, with the entire group result.
+        BSONObj retval;
+        PlanExecutor::ExecState state = planExecutor->getNext(&retval, NULL);
+        if (PlanExecutor::ADVANCED != state) {
+            invariant(PlanExecutor::FAILURE == state || PlanExecutor::DEAD == state);
+
+            if (WorkingSetCommon::isValidStatusMemberObject(retval)) {
+                return appendCommandStatus(result, WorkingSetCommon::getMemberObjectStatus(retval));
+            }
+            return appendCommandStatus(result,
+                                       Status(ErrorCodes::BadValue,
+                                              str::stream() << "error encountered during group "
+                                                            << "operation, executor returned "
+                                                            << PlanExecutor::statestr(state)));
+        }
+
+        invariant(planExecutor->isEOF());
+
+        invariant(STAGE_GROUP == planExecutor->getRootStage()->stageType());
+        GroupStage* groupStage = static_cast<GroupStage*>(planExecutor->getRootStage());
+        const GroupStats* groupStats =
+            static_cast<const GroupStats*>(groupStage->getSpecificStats());
+        const CommonStats* groupChildStats = groupStage->getChildren()[0]->getCommonStats();
+
+        result.appendArray("retval", retval);
+        result.append("count", static_cast<long long>(groupChildStats->advanced));
+        result.append("keys", static_cast<long long>(groupStats->nGroups));
+
+        return true;
+    }
+
+private:
+    /**
+     * Parse a group command object.
+     *
+     * If 'cmdObj' is well-formed, returns Status::OK() and fills in out-argument 'request'.
+     *
+     * If a parsing error is encountered, returns an error Status.
+     */
+    Status _parseRequest(const std::string& dbname,
+                         const BSONObj& cmdObj,
+                         GroupRequest* request) const {
+        request->ns = parseNs(dbname, cmdObj);
+
+        // By default, group requests are regular group not explain of group.
+        request->explain = false;
+
+        const BSONObj& p = cmdObj.firstElement().embeddedObjectUserCheck();
+
+        if (p["cond"].type() == Object) {
+            request->query = p["cond"].embeddedObject().getOwned();
+        } else if (p["condition"].type() == Object) {
+            request->query = p["condition"].embeddedObject().getOwned();
+        } else if (p["query"].type() == Object) {
+            request->query = p["query"].embeddedObject().getOwned();
+        } else if (p["q"].type() == Object) {
+            request->query = p["q"].embeddedObject().getOwned();
+        }
+
+        if (p["key"].type() == Object) {
+            request->keyPattern = p["key"].embeddedObjectUserCheck().getOwned();
+            if (!p["$keyf"].eoo()) {
+                return Status(ErrorCodes::BadValue, "can't have key and $keyf");
+            }
+        } else if (!p["$keyf"].eoo()) {
+            request->keyFunctionCode = p["$keyf"]._asCode();
+        } else {
+            // No key specified.  Use the entire object as the key.
+        }
+
+        BSONElement reduce = p["$reduce"];
+        if (reduce.eoo()) {
+            return Status(ErrorCodes::BadValue, "$reduce has to be set");
+        }
+        request->reduceCode = reduce._asCode();
+
+        if (reduce.type() == CodeWScope) {
+            request->reduceScope = reduce.codeWScopeObject().getOwned();
+        }
+
+        if (p["initial"].type() != Object) {
+            return Status(ErrorCodes::BadValue, "initial has to be an object");
+        }
+        request->initial = p["initial"].embeddedObject().getOwned();
+
+        if (!p["finalize"].eoo()) {
+            request->finalize = p["finalize"]._asCode();
+        }
+
+        return Status::OK();
+    }
+
+} cmdGroup;
+
+}  // namespace
+}  // namespace mongo