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Migrate pg_locks to collector package
Migrate the `pg_locks_count` query from `main` to the `collector` package. Signed-off-by: SuperQ <superq@gmail.com>
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‎README.md‎

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@@ -73,7 +73,10 @@ This will build the docker image as `prometheuscommunity/postgres_exporter:${bra
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* `[no-]collector.database`
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Enable the database collector (default: enabled).
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Enable the `database` collector (default: enabled).
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* `[no-]collector.locks`
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Enable the `locks` collector (default: enabled).
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* `[no-]collector.postmaster`
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Enable the `postmaster` collector (default: enabled).

‎cmd/postgres_exporter/postgres_exporter.go‎

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@@ -176,15 +176,6 @@ var builtinMetricMaps = map[string]intermediateMetricMap{
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true,
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0,
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},
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"pg_locks": {
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map[string]ColumnMapping{
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"datname": {LABEL, "Name of this database", nil, nil},
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"mode": {LABEL, "Type of Lock", nil, nil},
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"count": {GAUGE, "Number of locks", nil, nil},
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},
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true,
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0,
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},
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"pg_stat_replication": {
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map[string]ColumnMapping{
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"procpid": {DISCARD, "Process ID of a WAL sender process", nil, semver.MustParseRange("<9.2.0")},

‎cmd/postgres_exporter/queries.go‎

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@@ -46,31 +46,6 @@ type OverrideQuery struct {
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// Overriding queries for namespaces above.
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// TODO: validate this is a closed set in tests, and there are no overlaps
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var queryOverrides = map[string][]OverrideQuery{
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"pg_locks": {
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{
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semver.MustParseRange(">0.0.0"),
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`SELECT pg_database.datname,tmp.mode,COALESCE(count,0) as count
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FROM
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(
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VALUES ('accesssharelock'),
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('rowsharelock'),
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('rowexclusivelock'),
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('shareupdateexclusivelock'),
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('sharelock'),
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('sharerowexclusivelock'),
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('exclusivelock'),
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('accessexclusivelock'),
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('sireadlock')
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) AS tmp(mode) CROSS JOIN pg_database
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LEFT JOIN
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(SELECT database, lower(mode) AS mode,count(*) AS count
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FROM pg_locks WHERE database IS NOT NULL
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GROUP BY database, lower(mode)
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) AS tmp2
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ON tmp.mode=tmp2.mode and pg_database.oid = tmp2.database ORDER BY 1`,
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},
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},
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"pg_stat_replication": {
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{
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semver.MustParseRange(">=10.0.0"),

‎collector/pg_locks.go‎

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@@ -0,0 +1,119 @@
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// Copyright 2023 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package collector
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import (
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"context"
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"github.com/go-kit/log"
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"github.com/prometheus/client_golang/prometheus"
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)
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const locksSubsystem = "locks"
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func init() {
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registerCollector(locksSubsystem, defaultEnabled, NewPGLocksCollector)
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}
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type PGLocksCollector struct {
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log log.Logger
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}
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func NewPGLocksCollector(config collectorConfig) (Collector, error) {
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return &PGLocksCollector{
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log: config.logger,
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}, nil
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}
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var (
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pgLocksDesc = prometheus.NewDesc(
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prometheus.BuildFQName(
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namespace,
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locksSubsystem,
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"count",
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),
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"Number of locks",
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[]string{"datname", "mode"}, nil,
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)
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pgLocksQuery = `
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SELECT
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pg_database.datname as datname,
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tmp.mode as mode,
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COALESCE(count, 0) as count
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FROM
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(
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VALUES
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('accesssharelock'),
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('rowsharelock'),
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('rowexclusivelock'),
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('shareupdateexclusivelock'),
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('sharelock'),
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('sharerowexclusivelock'),
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('exclusivelock'),
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('accessexclusivelock'),
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('sireadlock')
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) AS tmp(mode) CROSS
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JOIN pg_database
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LEFT JOIN (
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SELECT
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database,
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lower(mode) AS mode,
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count(*) AS count
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FROM
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pg_locks
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WHERE
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database IS NOT NULL
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GROUP BY
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database,
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lower(mode)
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) AS tmp2 ON tmp.mode = tmp2.mode
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and pg_database.oid = tmp2.database
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ORDER BY
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1
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`
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)
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// Update implements Collector and exposes database locks.
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// It is called by the Prometheus registry when collecting metrics.
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func (c PGLocksCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
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db := instance.getDB()
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// Query the list of databases
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rows, err := db.QueryContext(ctx,
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pgLocksQuery,
95+
)
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if err != nil {
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return err
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}
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defer rows.Close()
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var datname, mode string
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var count int64
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for rows.Next() {
105+
if err := rows.Scan(&datname, &mode, &count); err != nil {
106+
return err
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}
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ch <- prometheus.MustNewConstMetric(
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pgLocksDesc,
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prometheus.GaugeValue, float64(count),
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datname, mode,
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)
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}
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if err := rows.Err(); err != nil {
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return err
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}
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return nil
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}

‎collector/pg_locks_test.go‎

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// Copyright 2023 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11+
// See the License for the specific language governing permissions and
12+
// limitations under the License.
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package collector
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import (
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"context"
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"testing"
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"github.com/DATA-DOG/go-sqlmock"
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"github.com/prometheus/client_golang/prometheus"
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dto "github.com/prometheus/client_model/go"
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"github.com/smartystreets/goconvey/convey"
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)
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func TestPGLocksCollector(t *testing.T) {
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db, mock, err := sqlmock.New()
27+
if err != nil {
28+
t.Fatalf("Error opening a stub db connection: %s", err)
29+
}
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defer db.Close()
31+
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inst := &instance{db: db}
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rows := sqlmock.NewRows([]string{"datname", "mode", "count"}).
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AddRow("test", "exclusivelock", 42)
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mock.ExpectQuery(sanitizeQuery(pgLocksQuery)).WillReturnRows(rows)
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ch := make(chan prometheus.Metric)
40+
go func() {
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defer close(ch)
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c := PGLocksCollector{}
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if err := c.Update(context.Background(), inst, ch); err != nil {
44+
t.Errorf("Error calling PGLocksCollector.Update: %s", err)
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}
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}()
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expected := []MetricResult{
49+
{labels: labelMap{"datname": "test", "mode": "exclusivelock"}, value: 42, metricType: dto.MetricType_GAUGE},
50+
}
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convey.Convey("Metrics comparison", t, func() {
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for _, expect := range expected {
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m := readMetric(<-ch)
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convey.So(expect, convey.ShouldResemble, m)
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}
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})
57+
if err := mock.ExpectationsWereMet(); err != nil {
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t.Errorf("there were unfulfilled exceptions: %s", err)
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}
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}

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