Log when starting to create a checkpoint (#7581)

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>

tsdb/db_test.go

@@ -1169,7 +1169,7 @@ func TestSizeRetention(t *testing.T) {
 	// Create a WAL checkpoint, and compare sizes.
 	first, last, err := db.Head().wal.Segments()
 	testutil.Ok(t, err)
-	_, err = wal.Checkpoint(db.Head().wal, first, last-1, func(x uint64) bool { return false }, 0)
+	_, err = wal.Checkpoint(log.NewNopLogger(), db.Head().wal, first, last-1, func(x uint64) bool { return false }, 0)
 	testutil.Ok(t, err)
 	blockSize = int64(prom_testutil.ToFloat64(db.metrics.blocksBytes)) // Use the actual internal metrics.
 	walSize, err = db.Head().wal.Size()

tsdb/head.go

@@ -835,7 +835,7 @@ func (h *Head) Truncate(mint int64) (err error) {
 		return ok
 	}
 	h.metrics.checkpointCreationTotal.Inc()
-	if _, err = wal.Checkpoint(h.wal, first, last, keep, mint); err != nil {
+	if _, err = wal.Checkpoint(h.logger, h.wal, first, last, keep, mint); err != nil {
 		h.metrics.checkpointCreationFail.Inc()
 		if _, ok := errors.Cause(err).(*wal.CorruptionErr); ok {
 			h.metrics.walCorruptionsTotal.Inc()

tsdb/wal/checkpoint.go

@@ -25,6 +25,8 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/go-kit/kit/log"
+	"github.com/go-kit/kit/log/level"
 	"github.com/pkg/errors"
 	tsdb_errors "github.com/prometheus/prometheus/tsdb/errors"
 	"github.com/prometheus/prometheus/tsdb/fileutil"
@@ -87,10 +89,12 @@ const checkpointPrefix = "checkpoint."
 // segmented format as the original WAL itself.
 // This makes it easy to read it through the WAL package and concatenate
 // it with the original WAL.
-func Checkpoint(w *WAL, from, to int, keep func(id uint64) bool, mint int64) (*CheckpointStats, error) {
+func Checkpoint(logger log.Logger, w *WAL, from, to int, keep func(id uint64) bool, mint int64) (*CheckpointStats, error) {
 	stats := &CheckpointStats{}
 	var sgmReader io.ReadCloser
 
+	level.Info(logger).Log("msg", "Creating checkpoint", "from_segment", from, "to_segment", to, "mint", mint)
+
 	{
 
 		var sgmRange []SegmentRange

tsdb/wal/checkpoint_test.go

@@ -16,6 +16,7 @@ package wal
 
 import (
 	"fmt"
+	"github.com/go-kit/kit/log"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -177,7 +178,7 @@ func TestCheckpoint(t *testing.T) {
 			}
 			testutil.Ok(t, w.Close())
 
-			_, err = Checkpoint(w, 100, 106, func(x uint64) bool {
+			_, err = Checkpoint(log.NewNopLogger(), w, 100, 106, func(x uint64) bool {
 				return x%2 == 0
 			}, last/2)
 			testutil.Ok(t, err)
@@ -236,7 +237,7 @@ func TestCheckpointNoTmpFolderAfterError(t *testing.T) {
 	w.Close()
 
 	// Run the checkpoint and since the wal contains an invalid records this should return an error.
-	_, err = Checkpoint(w, 0, 1, nil, 0)
+	_, err = Checkpoint(log.NewNopLogger(), w, 0, 1, nil, 0)
 	testutil.NotOk(t, err)
 
 	// Walk the wal dir to make sure there are no tmp folder left behind after the error.

tsdb/wal/watcher_test.go

@@ -14,6 +14,7 @@ package wal
 
 import (
 	"fmt"
+	"github.com/go-kit/kit/log"
 	"io/ioutil"
 	"math/rand"
 	"os"
@@ -275,7 +276,7 @@ func TestReadToEndWithCheckpoint(t *testing.T) {
 				}
 			}
 
-			Checkpoint(w, 0, 1, func(x uint64) bool { return true }, 0)
+			Checkpoint(log.NewNopLogger(), w, 0, 1, func(x uint64) bool { return true }, 0)
 			w.Truncate(1)
 
 			// Write more records after checkpointing.
@@ -360,7 +361,7 @@ func TestReadCheckpoint(t *testing.T) {
 					testutil.Ok(t, w.Log(sample))
 				}
 			}
-			Checkpoint(w, 30, 31, func(x uint64) bool { return true }, 0)
+			Checkpoint(log.NewNopLogger(), w, 30, 31, func(x uint64) bool { return true }, 0)
 			w.Truncate(32)
 
 			// Start read after checkpoint, no more data written.
@@ -520,7 +521,7 @@ func TestCheckpointSeriesReset(t *testing.T) {
 			})
 			testutil.Equals(t, seriesCount, wt.checkNumLabels())
 
-			_, err = Checkpoint(w, 2, 4, func(x uint64) bool { return true }, 0)
+			_, err = Checkpoint(log.NewNopLogger(), w, 2, 4, func(x uint64) bool { return true }, 0)
 			testutil.Ok(t, err)
 
 			err = w.Truncate(5)