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/**
* Copyright (C) 2019-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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/base/simple_string_data_comparator.h"
#include "mongo/base/string_data.h"
#include "mongo/base/string_data_comparator_interface.h"
#include "mongo/db/client.h"
#include "mongo/db/commands/server_status.h"
#include "mongo/db/service_context.h"
#include "mongo/stdx/unordered_map.h"
#include "mongo/stdx/unordered_set.h"
namespace mongo {
/**
* LatchAnalyzer is a ServiceContext decoration that aggregates latch events
*
* This class is intended to provide a platform for hierarchical analysis on latches. To that end,
* onContention(), onAcquire(), and onRelease() are currently called by a
* latch_detail::DiagnosticListener subclass defined in source. This class does much more work for
* each event when the enableLatchAnalysis failpoint is set to "alwaysOn". This failpoint provides a
* wealth of data for future analysis, but involves additional mutexes and mapping structures that
* may prove too costly for production usage at the least.
*/
class LatchAnalyzer {
public:
static LatchAnalyzer& get(ServiceContext* serviceContext);
static LatchAnalyzer& get(Client* client);
static LatchAnalyzer& get();
// Handler function for a failed latch acquire
void onContention(const latch_detail::Identity& id);
// Handler function for a successful latch acquire
void onAcquire(const latch_detail::Identity& id);
// Handler function for a latch release
void onRelease(const latch_detail::Identity& id);
// Append the current statistics in a form appropriate for server status to a BOB
void appendToBSON(mongo::BSONObjBuilder& result) const;
// Log the current statistics in JSON form to INFO
void dump();
void setAllowExitOnViolation(bool allowExitOnViolation);
bool allowExitOnViolation();
private:
struct HierarchyStats {
const latch_detail::Identity* identity = nullptr;
int acquiredAfter = 0;
int releasedBefore = 0;
};
using SingleLatchHierarchy = stdx::unordered_map<int64_t, HierarchyStats>;
struct HierarchicalAcquisitionLevelViolation {
int onAcquire = 0;
int onRelease = 0;
};
// Either warn about the violation or crash the process.
void _handleViolation(ErrorCodes::Error ec,
StringData message,
const latch_detail::Identity& identity,
Client* client) noexcept;
void _handleAcquireViolation(ErrorCodes::Error ec,
StringData message,
const latch_detail::Identity& identity,
Client* client) noexcept;
void _handleReleaseViolation(ErrorCodes::Error ec,
StringData message,
const latch_detail::Identity& identity,
Client* client) noexcept;
AtomicWord<bool> _allowExitOnViolation{true};
mutable stdx::mutex _mutex; // NOLINT
stdx::unordered_map<int64_t, SingleLatchHierarchy> _hierarchies;
stdx::unordered_map<int64_t, HierarchicalAcquisitionLevelViolation> _violations;
};
class LatchAnalyzerDisabledBlock {
public:
LatchAnalyzerDisabledBlock();
~LatchAnalyzerDisabledBlock();
};
} // namespace mongo
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