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/**
* Copyright (C) 2022-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/status.h"
#include "mongo/db/concurrency/d_concurrency.h"
#include "mongo/db/curop.h"
#include "mongo/db/query/partitioned_cache.h"
#include "mongo/db/query/plan_explainer.h"
#include "mongo/db/query/util/memory_util.h"
#include "mongo/db/service_context.h"
namespace mongo {
class OpDebug;
class AggregateCommandRequest;
class FindCommandRequest;
namespace {
/**
* Type we use to render values to BSON.
*/
using BSONNumeric = long long;
} // namespace
namespace telemetry {
/**
* An aggregated metric stores a compressed view of data. It balances the loss of information with
* the reduction in required storage.
*/
struct AggregatedMetric {
/**
* Aggregate an observed value into the metric.
*/
void aggregate(uint64_t val) {
sum += val;
max = std::max(val, max);
min = std::min(val, min);
sumOfSquares += val * val;
}
void appendTo(BSONObjBuilder& builder, const StringData& fieldName) const {
BSONObjBuilder metricsBuilder = builder.subobjStart(fieldName);
metricsBuilder.append("sum", (BSONNumeric)sum);
metricsBuilder.append("max", (BSONNumeric)max);
metricsBuilder.append("min", (BSONNumeric)min);
metricsBuilder.append("sumOfSquares", (BSONNumeric)sumOfSquares);
metricsBuilder.done();
}
uint64_t sum = 0;
// Default to the _signed_ maximum (which fits in unsigned range) because we cast to BSONNumeric
// when serializing.
uint64_t min = (uint64_t)std::numeric_limits<int64_t>::max;
uint64_t max = 0;
/**
* The sum of squares along with (an externally stored) count will allow us to compute the
* variance/stddev.
*/
uint64_t sumOfSquares = 0;
};
class TelemetryMetrics {
public:
TelemetryMetrics() : firstSeenTimestamp(Date_t::now().toMillisSinceEpoch() / 1000, 0) {}
BSONObj toBSON() const {
BSONObjBuilder builder{sizeof(TelemetryMetrics) + 100};
builder.append("lastExecutionMicros", (BSONNumeric)lastExecutionMicros);
builder.append("execCount", (BSONNumeric)execCount);
queryOptMicros.appendTo(builder, "queryOptMicros");
queryExecMicros.appendTo(builder, "queryExecMicros");
docsReturned.appendTo(builder, "docsReturned");
docsScanned.appendTo(builder, "docsScanned");
keysScanned.appendTo(builder, "keysScanned");
builder.append("firstSeenTimestamp", firstSeenTimestamp);
return builder.obj();
}
/**
* Redact a given telemetry key.
*/
const BSONObj& redactKey(const BSONObj& key) const;
/**
* Timestamp for when this query shape was added to the store. Set on construction.
*/
const Timestamp firstSeenTimestamp;
/**
* Last execution time in microseconds.
*/
uint64_t lastExecutionMicros = 0;
/**
* Number of query executions.
*/
uint64_t execCount = 0;
AggregatedMetric queryOptMicros;
AggregatedMetric queryExecMicros;
AggregatedMetric docsReturned;
AggregatedMetric docsScanned;
AggregatedMetric keysScanned;
private:
/**
* We cache the redacted key the first time it's computed.
*/
mutable boost::optional<BSONObj> _redactedKey;
};
struct TelemetryPartitioner {
// The partitioning function for use with the 'Partitioned' utility.
std::size_t operator()(const BSONObj& k, const std::size_t nPartitions) const {
return SimpleBSONObjComparator::Hasher()(k) % nPartitions;
}
};
/**
* Average key size used to pad the metrics size. We store a cached redaction of the key in the
* TelemetryMetrics object.
*/
const size_t kAverageKeySize = 100;
struct ComputeEntrySize {
size_t operator()(const TelemetryMetrics& entry) {
return sizeof(TelemetryMetrics) + kAverageKeySize;
}
};
using TelemetryStore = PartitionedCache<BSONObj,
TelemetryMetrics,
ComputeEntrySize,
TelemetryPartitioner,
SimpleBSONObjComparator::Hasher,
SimpleBSONObjComparator::EqualTo>;
/**
* Acquire a reference to the global telemetry store.
*/
std::pair<TelemetryStore*, Lock::ResourceLock> getTelemetryStoreForRead(
const ServiceContext* serviceCtx);
std::unique_ptr<TelemetryStore> resetTelemetryStore(const ServiceContext* serviceCtx);
/**
* Register a request for telemetry collection. The telemetry machinery may decide not to collect
* anything but this should be called for all requests. The decision is made based on the feature
* flag and telemetry parameters such as rate limiting.
*
* The caller is still responsible for subsequently calling collectTelemetry() once the request is
* completed.
*
* Note that calling this affects internal state. It should be called once for each request for
* which telemetry may be collected.
*/
void registerAggRequest(const AggregateCommandRequest& request, OperationContext* opCtx);
void registerFindRequest(const FindCommandRequest& request,
const NamespaceString& collection,
OperationContext* opCtx);
void registerGetMoreRequest(OperationContext* opCtx, const PlanExplainer& planExplainer);
void recordExecution(OperationContext* opCtx, const OpDebug& opDebug, bool isFle);
/**
* Collect telemetry for the operation identified by `key`. The `isExec` flag should be set if it's
* the beginning of execution (first batch) of results and not set for subsequent getMore() calls.
*/
void collectTelemetry(const OperationContext* opCtx, const OpDebug& opDebug);
} // namespace telemetry
} // namespace mongo
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