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/**
* Copyright (C) 2013-2014 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.
*/
#pragma once
#include "mongo/db/exec/plan_stage.h"
#include "mongo/db/exec/plan_stats.h"
#include "mongo/db/query/canonical_query.h"
#include "mongo/db/query/explain_common.h"
#include "mongo/db/query/plan_executor.h"
#include "mongo/db/query/query_planner_params.h"
#include "mongo/db/query/query_solution.h"
namespace mongo {
class Collection;
class OperationContext;
/**
* A container for the summary statistics that the profiler, slow query log, and
* other non-explain debug mechanisms may want to collect.
*/
struct PlanSummaryStats {
PlanSummaryStats() : nReturned(0),
totalKeysExamined(0),
totalDocsExamined(0),
isIdhack(false),
hasSortStage(false),
summaryStr("") { }
// The number of results returned by the plan.
size_t nReturned;
// The total number of index keys examined by the plan.
size_t totalKeysExamined;
// The total number of documents examined by the plan.
size_t totalDocsExamined;
// The number of milliseconds spent inside the root stage's work() method.
long long executionTimeMillis;
// Did this plan use the fast path for key-value retrievals on the _id index?
bool isIdhack;
// Did this plan use an in-memory sort stage?
bool hasSortStage;
// A string summarizing the plan selected.
std::string summaryStr;
};
/**
* Namespace for the collection of static methods used to generate explain information.
*/
class Explain {
public:
/**
* Get explain BSON for the execution stages contained by 'exec'. Use this function if you
* have a PlanExecutor and want to convert it into a human readable explain format. Any
* operation which has a query component (e.g. find, update, group) can be explained via
* this function.
*
* The explain information is extracted from 'exec' and added to the out-parameter 'out'.
*
* The explain information is generated with the level of detail specified by 'verbosity'.
*
* Does not take ownership of its arguments.
*/
static Status explainStages(OperationContext* opCtx,
PlanExecutor* exec,
ExplainCommon::Verbosity verbosity,
BSONObjBuilder* out);
/**
* Converts the stats tree 'stats' into a corresponding BSON object containing
* explain information.
*
* Generates the BSON stats at a verbosity specified by 'verbosity'. Defaults
* to the highest verbosity (FULL).
*/
static BSONObj statsToBSON(const PlanStageStats& stats,
ExplainCommon::Verbosity verbosity = ExplainCommon::FULL);
/**
* This version of stats tree to BSON conversion returns the result through the
* out-parameter 'bob' rather than returning a BSONObj.
*
* Generates the BSON stats at a verbosity specified by 'verbosity'. Defaults
* to the highest verbosity (FULL).
*/
static void statsToBSON(const PlanStageStats& stats,
BSONObjBuilder* bob,
ExplainCommon::Verbosity verbosity = ExplainCommon::FULL);
/**
* Returns a short plan summary std::string describing the leaves of the query plan.
*/
static std::string getPlanSummary(PlanExecutor* exec);
static std::string getPlanSummary(PlanStage* root);
/**
* Fills out 'statsOut' with summary stats using the execution tree contained
* in 'exec'.
*
* The summary stats are consumed by debug mechanisms such as the profiler and
* the slow query log.
*
* This is a lightweight alternative for explainStages(...) above which is useful
* when operations want to request debug information without doing all the work
* to generate a full explain.
*
* Does not take ownership of its arguments.
*/
static void getSummaryStats(PlanExecutor* exec, PlanSummaryStats* statsOut);
private:
/**
* Private helper that does the heavy-lifting for the public statsToBSON(...) functions
* declared above.
*
* Not used except as a helper to the public statsToBSON(...) functions.
*/
static void statsToBSON(const PlanStageStats& stats,
ExplainCommon::Verbosity verbosity,
BSONObjBuilder* bob,
BSONObjBuilder* topLevelBob);
/**
* Adds the 'queryPlanner' explain section to the BSON object being built
* by 'out'.
*
* This is a helper for generating explain BSON. It is used by explainStages(...).
*
* @param query -- the query part of the operation being explained.
* @param winnerStats -- the stats tree for the winning plan.
* @param rejectedStats -- an array of stats trees, one per rejected plan
*/
static void generatePlannerInfo(CanonicalQuery* query,
PlanStageStats* winnerStats,
const vector<PlanStageStats*>& rejectedStats,
BSONObjBuilder* out);
/**
* Generates the execution stats section for the stats tree 'stats',
* adding the resulting BSON to 'out'.
*
* The 'totalTimeMillis' value passed here will be added to the top level of
* the execution stats section, but will not affect the reporting of timing for
* individual stages. If 'totalTimeMillis' is not specified, then the default
* value of -1 indicates that we should only use the approximate timing information
* collected by the stages.
*
* Stats are generated at the verbosity specified by 'verbosity'.
*
* This is a helper for generating explain BSON. It is used by explainStages(...).
*/
static void generateExecStats(PlanStageStats* stats,
ExplainCommon::Verbosity verbosity,
BSONObjBuilder* out,
long long totalTimeMillis = -1);
/**
* Adds the 'serverInfo' explain section to the BSON object being build
* by 'out'.
*
* This is a helper for generating explain BSON. It is used by explainStages(...).
*/
static void generateServerInfo(BSONObjBuilder* out);
};
} // namespace
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