// Copyright 2024 Google LLC

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

// https://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

package spanner

import (

"context"

"log"

"sync"

"cloud.google.com/go/spanner/internal"

"go.opentelemetry.io/otel"

"go.opentelemetry.io/otel/attribute"

"go.opentelemetry.io/otel/metric"

"go.opentelemetry.io/otel/trace"

"google.golang.org/grpc/metadata"

)

// OtInstrumentationScope is the instrumentation name that will be associated with the emitted telemetry.

const OtInstrumentationScope = "cloud.google.com/go"

const metricsPrefix = "spanner/"

var (

attributeKeyClientID = attribute.Key("client_id")

attributeKeyDatabase = attribute.Key("database")

attributeKeyInstance = attribute.Key("instance_id")

attributeKeyLibVersion = attribute.Key("library_version")

attributeKeyType = attribute.Key("type")

attributeKeyMethod = attribute.Key("grpc_client_method")

attributeKeyIsMultiplexed = attribute.Key("is_multiplexed")

attributeNumInUseSessions = attributeKeyType.String("num_in_use_sessions")

attributeNumSessions = attributeKeyType.String("num_sessions")

// openTelemetryMetricsEnabled is used to track if OpenTelemetry Metrics need to be recorded

openTelemetryMetricsEnabled = false

// mutex to avoid data race in reading/writing the above flag

otMu = sync.RWMutex{}

)

func createOpenTelemetryConfig(ctx context.Context, mp metric.MeterProvider, logger *log.Logger, sessionClientID string, db string) (*openTelemetryConfig, error) {

// Important: snapshot the value of the global variable to ensure a

// consistent value for the lifetime of this client.

enabled := IsOpenTelemetryMetricsEnabled()

_, instance, database, err := parseDatabaseName(db)

if err != nil {

return nil, err

}

config := &openTelemetryConfig{

enabled: enabled,

attributeMap: []attribute.KeyValue{},

commonTraceStartOptions: []trace.SpanStartOption{

trace.WithAttributes(

attribute.String("db.name", database),

attribute.String("instance.name", instance),

attribute.String("cloud.region", detectClientLocation(ctx)),

attribute.String("gcp.client.version", internal.Version),

attribute.String("gcp.client.repo", gcpClientRepo),

attribute.String("gcp.client.artifact", gcpClientArtifact),

attribute.String("gcp.resource.name", GcpResourceNamePrefix+db),

),

},

}

if !enabled {

return config, nil

}

// Construct attributes for Metrics

attributeMap := []attribute.KeyValue{

attributeKeyClientID.String(sessionClientID),

attributeKeyDatabase.String(database),

attributeKeyInstance.String(instance),

attributeKeyLibVersion.String(internal.Version),

}

config.attributeMap = append(config.attributeMap, attributeMap...)

config.attributeMapWithMultiplexed = append(config.attributeMapWithMultiplexed, attributeMap...)

config.attributeMapWithMultiplexed = append(config.attributeMapWithMultiplexed, attributeKeyIsMultiplexed.String("true"))

setOpenTelemetryMetricProvider(config, mp, logger)

return config, nil

}

func setOpenTelemetryMetricProvider(config *openTelemetryConfig, mp metric.MeterProvider, logger *log.Logger) {

// Fallback to global meter provider in OpenTelemetry

if mp == nil {

mp = otel.GetMeterProvider()

}

config.meterProvider = mp

initializeMetricInstruments(config, logger)

}

func initializeMetricInstruments(config *openTelemetryConfig, logger *log.Logger) {

if !config.enabled {

return

}

meter := config.meterProvider.Meter(OtInstrumentationScope, metric.WithInstrumentationVersion(internal.Version))

openSessionCountInstrument, err := meter.Int64ObservableGauge(

metricsPrefix+"open_session_count",

metric.WithDescription("Number of sessions currently opened"),

metric.WithUnit("1"),

)

if err != nil {

logf(logger, "Error during registering instrument for metric spanner/open_session_count, error: %v", err)

}

config.openSessionCount = openSessionCountInstrument

getSessionTimeoutsCountInstrument, err := meter.Int64Counter(

metricsPrefix+"get_session_timeouts",

metric.WithDescription("The number of get sessions timeouts due to pool exhaustion."),

metric.WithUnit("1"),

)

if err != nil {

logf(logger, "Error during registering instrument for metric spanner/get_session_timeouts, error: %v", err)

}

config.getSessionTimeoutsCount = getSessionTimeoutsCountInstrument

acquiredSessionsCountInstrument, err := meter.Int64Counter(

metricsPrefix+"num_acquired_sessions",

metric.WithDescription("The number of sessions acquired from the session pool."),

metric.WithUnit("1"),

)

if err != nil {

logf(logger, "Error during registering instrument for metric spanner/num_acquired_sessions, error: %v", err)

}

config.acquiredSessionsCount = acquiredSessionsCountInstrument

releasedSessionsCountInstrument, err := meter.Int64Counter(

metricsPrefix+"num_released_sessions",

metric.WithDescription("The number of sessions released by the user and pool maintainer."),

metric.WithUnit("1"),

)

if err != nil {

logf(logger, "Error during registering instrument for metric spanner/num_released_sessions, error: %v", err)

}

config.releasedSessionsCount = releasedSessionsCountInstrument

gfeLatencyInstrument, err := meter.Int64Histogram(

metricsPrefix+"gfe_latency",

metric.WithDescription("Latency between Google's network receiving an RPC and reading back the first byte of the response"),

metric.WithUnit("ms"),

metric.WithExplicitBucketBoundaries(0.0, 0.01, 0.05, 0.1, 0.3, 0.6, 0.8, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 8.0, 10.0, 13.0,

16.0, 20.0, 25.0, 30.0, 40.0, 50.0, 65.0, 80.0, 100.0, 130.0, 160.0, 200.0, 250.0,

300.0, 400.0, 500.0, 650.0, 800.0, 1000.0, 2000.0, 5000.0, 10000.0, 20000.0, 50000.0,

100000.0),

)

if err != nil {

logf(logger, "Error during registering instrument for metric spanner/gfe_latency, error: %v", err)

}

config.gfeLatency = gfeLatencyInstrument

gfeHeaderMissingCountInstrument, err := meter.Int64Counter(

metricsPrefix+"gfe_header_missing_count",

metric.WithDescription("Number of RPC responses received without the server-timing header, most likely means that the RPC never reached Google's network"),

metric.WithUnit("1"),

)

if err != nil {

logf(logger, "Error during registering instrument for metric spanner/gfe_header_missing_count, error: %v", err)

}

config.gfeHeaderMissingCount = gfeHeaderMissingCountInstrument

}

func registerSessionManagerOTMetrics(sm *sessionManager) error {

otConfig := sm.otConfig

if otConfig == nil || !otConfig.enabled {

return nil

}

reg, err := otConfig.meterProvider.Meter(OtInstrumentationScope, metric.WithInstrumentationVersion(internal.Version)).RegisterCallback(

func(ctx context.Context, o metric.Observer) error {

sm.mu.Lock()

defer sm.mu.Unlock()

if sm.multiplexedSession != nil {

o.ObserveInt64(otConfig.openSessionCount, int64(1), metric.WithAttributes(otConfig.attributeMapWithMultiplexed...))

} else {

o.ObserveInt64(otConfig.openSessionCount, int64(0), metric.WithAttributes(otConfig.attributeMapWithMultiplexed...))

}

return nil

},

otConfig.openSessionCount,

)

sm.otConfig.otMetricRegistration = reg

return err

}

// EnableOpenTelemetryMetrics enables OpenTelemetery metrics

func EnableOpenTelemetryMetrics() {

setOpenTelemetryMetricsFlag(true)

}

// IsOpenTelemetryMetricsEnabled tells whether OpenTelemtery metrics is enabled or not.

func IsOpenTelemetryMetricsEnabled() bool {

otMu.RLock()

defer otMu.RUnlock()

return openTelemetryMetricsEnabled

}

func setOpenTelemetryMetricsFlag(enable bool) {

otMu.Lock()

openTelemetryMetricsEnabled = enable

otMu.Unlock()

}

func recordGFELatencyMetricsOT(ctx context.Context, md metadata.MD, keyMethod string, otConfig *openTelemetryConfig) error {

if otConfig == nil || !otConfig.enabled || md == nil {

return nil

}

attr := otConfig.attributeMap

metrics := parseServerTimingHeader(md)

if len(metrics) == 0 && otConfig.gfeHeaderMissingCount != nil {

otConfig.gfeHeaderMissingCount.Add(ctx, 1, metric.WithAttributes(attr...))

return nil

}

attr = append(attr, attributeKeyMethod.String(keyMethod))

if otConfig.gfeLatency != nil {

otConfig.gfeLatency.Record(ctx, metrics[gfeTimingHeader].Milliseconds(), metric.WithAttributes(attr...))

}

return nil

}