Allow manual compaction for tests when compaction is disabled globally. (#412)

for tests we need to control when a compaction happens so with this
change automated compaction can be disabled, but allow to run it
manually it tests.

fixes failing tests in : https://github.com/prometheus/tsdb/pull/374

Signed-off-by: Krasi Georgiev <kgeorgie@redhat.com>

compact_test.go

@@ -19,10 +19,13 @@ import (
 	"os"
 	"path/filepath"
 	"testing"
+	"time"
 
 	"github.com/go-kit/kit/log"
 	"github.com/pkg/errors"
+	dto "github.com/prometheus/client_model/go"
 	"github.com/prometheus/tsdb/chunks"
+	"github.com/prometheus/tsdb/labels"
 	"github.com/prometheus/tsdb/testutil"
 )
 
@@ -682,3 +685,59 @@ func TestCompaction_populateBlock(t *testing.T) {
 		}
 	}
 }
+
+// TestDisableAutoCompactions checks that we can
+// disable and enable the auto compaction.
+// This is needed for unit tests that rely on
+// checking state before and after a compaction.
+func TestDisableAutoCompactions(t *testing.T) {
+	db, close := openTestDB(t, nil)
+	defer close()
+	defer db.Close()
+
+	blockRange := DefaultOptions.BlockRanges[0]
+	label := labels.FromStrings("foo", "bar")
+
+	// Trigger a compaction to check that it was skipped and
+	// no new blocks were created when compaction is disabled.
+	db.DisableCompactions()
+	app := db.Appender()
+	for i := int64(0); i < 3; i++ {
+		_, err := app.Add(label, i*blockRange, 0)
+		testutil.Ok(t, err)
+		_, err = app.Add(label, i*blockRange+1000, 0)
+		testutil.Ok(t, err)
+	}
+	testutil.Ok(t, app.Commit())
+
+	select {
+	case db.compactc <- struct{}{}:
+	default:
+	}
+
+	m := &dto.Metric{}
+	for x := 0; x < 10; x++ {
+		db.metrics.compactionsSkipped.Write(m)
+		if *m.Counter.Value > float64(0) {
+			break
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+
+	testutil.Assert(t, *m.Counter.Value > float64(0), "No compaction was skipped after the set timeout.")
+	testutil.Equals(t, 0, len(db.blocks))
+
+	// Enable the compaction, trigger it and check that the block is persisted.
+	db.EnableCompactions()
+	select {
+	case db.compactc <- struct{}{}:
+	default:
+	}
+	for x := 0; x < 10; x++ {
+		if len(db.Blocks()) > 0 {
+			break
+		}
+		time.Sleep(30 * time.Millisecond)
+	}
+	testutil.Assert(t, len(db.Blocks()) > 0, "No block was persisted after the set timeout.")
+}

db.go

@@ -112,9 +112,13 @@ type DB struct {
 	donec    chan struct{}
 	stopc    chan struct{}
 
-	// cmtx is used to control compactions and deletions.
+	// cmtx ensures that compactions and deletions don't run simultaneously.
 	cmtx sync.Mutex
-	compactionsEnabled bool
+
+	// autoCompactMtx ensures that no compaction gets triggered while
+	// changing the autoCompact var.
+	autoCompactMtx sync.Mutex
+	autoCompact    bool
 }
 
 type dbMetrics struct {
@@ -123,6 +127,7 @@ type dbMetrics struct {
 	reloads              prometheus.Counter
 	reloadsFailed        prometheus.Counter
 	compactionsTriggered prometheus.Counter
+	compactionsSkipped   prometheus.Counter
 	cutoffs              prometheus.Counter
 	cutoffsFailed        prometheus.Counter
 	startTime            prometheus.GaugeFunc
@@ -165,6 +170,10 @@ func newDBMetrics(db *DB, r prometheus.Registerer) *dbMetrics {
 		Name: "prometheus_tsdb_compactions_triggered_total",
 		Help: "Total number of triggered compactions for the partition.",
 	})
+	m.compactionsSkipped = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "prometheus_tsdb_compactions_skipped_total",
+		Help: "Total number of skipped compactions due to disabled auto compaction.",
+	})
 	m.cutoffs = prometheus.NewCounter(prometheus.CounterOpts{
 		Name: "prometheus_tsdb_retention_cutoffs_total",
 		Help: "Number of times the database cut off block data from disk.",
@@ -232,7 +241,7 @@ func Open(dir string, l log.Logger, r prometheus.Registerer, opts *Options) (db
 		compactc:    make(chan struct{}, 1),
 		donec:       make(chan struct{}),
 		stopc:       make(chan struct{}),
-		compactionsEnabled: true,
+		autoCompact: true,
 		chunkPool:   chunkenc.NewPool(),
 	}
 	db.metrics = newDBMetrics(db, r)
@@ -300,14 +309,18 @@ func (db *DB) run() {
 		case <-db.compactc:
 			db.metrics.compactionsTriggered.Inc()
 
-			err := db.compact()
+			db.autoCompactMtx.Lock()
-			if err != nil {
+			if db.autoCompact {
+				if err := db.compact(); err != nil {
 					level.Error(db.logger).Log("msg", "compaction failed", "err", err)
 					backoff = exponential(backoff, 1*time.Second, 1*time.Minute)
 				} else {
 					backoff = 0
 				}
-
+			} else {
+				db.metrics.compactionsSkipped.Inc()
+			}
+			db.autoCompactMtx.Unlock()
 		case <-db.stopc:
 			return
 		}
@@ -369,11 +382,6 @@ func (a dbAppender) Commit() error {
 func (db *DB) compact() (err error) {
 	db.cmtx.Lock()
 	defer db.cmtx.Unlock()
-
-	if !db.compactionsEnabled {
-		return nil
-	}
-
 	// Check whether we have pending head blocks that are ready to be persisted.
 	// They have the highest priority.
 	for {
@@ -731,21 +739,21 @@ func (db *DB) Close() error {
 	return merr.Err()
 }
 
-// DisableCompactions disables compactions.
+// DisableCompactions disables auto compactions.
 func (db *DB) DisableCompactions() {
-	db.cmtx.Lock()
+	db.autoCompactMtx.Lock()
-	defer db.cmtx.Unlock()
+	defer db.autoCompactMtx.Unlock()
 
-	db.compactionsEnabled = false
+	db.autoCompact = false
 	level.Info(db.logger).Log("msg", "compactions disabled")
 }
 
-// EnableCompactions enables compactions.
+// EnableCompactions enables auto compactions.
 func (db *DB) EnableCompactions() {
-	db.cmtx.Lock()
+	db.autoCompactMtx.Lock()
-	defer db.cmtx.Unlock()
+	defer db.autoCompactMtx.Unlock()
 
-	db.compactionsEnabled = true
+	db.autoCompact = true
 	level.Info(db.logger).Log("msg", "compactions enabled")
 }