From 0967683ae96e8aebf3c0d7b25f22b580920bfaf7 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Tue, 13 Aug 2019 01:45:22 +0300
Subject: [PATCH] lib: move common code for creating flock.lock file into
 fs.CreateFlockFile

---
 lib/fs/fs.go           | 15 +++++++++++++++
 lib/mergeset/table.go  |  8 ++------
 lib/storage/storage.go | 10 +++-------
 lib/storage/table.go   | 10 +++-------
 4 files changed, 23 insertions(+), 20 deletions(-)

diff --git a/lib/fs/fs.go b/lib/fs/fs.go
index ddc65390f..617c835a6 100644
--- a/lib/fs/fs.go
+++ b/lib/fs/fs.go
@@ -13,6 +13,7 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/filestream"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/metrics"
+	"golang.org/x/sys/unix"
 )
 
 // ReadAtCloser is rand-access read interface.
@@ -385,3 +386,17 @@ func MustWriteData(w io.Writer, data []byte) {
 		logger.Panicf("BUG: writer wrote %d bytes instead of %d bytes", n, len(data))
 	}
 }
+
+// CreateFlockFile creates flock.lock file in the directory dir
+// and returns the handler to the file.
+func CreateFlockFile(dir string) (*os.File, error) {
+	flockFile := dir + "/flock.lock"
+	flockF, err := os.Create(flockFile)
+	if err != nil {
+		return nil, fmt.Errorf("cannot create lock file %q: %s", flockFile, err)
+	}
+	if err := unix.Flock(int(flockF.Fd()), unix.LOCK_EX|unix.LOCK_NB); err != nil {
+		return nil, fmt.Errorf("cannot acquire lock on file %q: %s", flockFile, err)
+	}
+	return flockF, nil
+}
diff --git a/lib/mergeset/table.go b/lib/mergeset/table.go
index 06110b395..5daa9de2b 100644
--- a/lib/mergeset/table.go
+++ b/lib/mergeset/table.go
@@ -134,13 +134,9 @@ func OpenTable(path string) (*Table, error) {
 	}
 
 	// Protect from concurrent opens.
-	flockFile := path + "/flock.lock"
-	flockF, err := os.Create(flockFile)
+	flockF, err := fs.CreateFlockFile(path)
 	if err != nil {
-		return nil, fmt.Errorf("cannot create lock file %q: %s", flockFile, err)
-	}
-	if err := unix.Flock(int(flockF.Fd()), unix.LOCK_EX|unix.LOCK_NB); err != nil {
-		return nil, fmt.Errorf("cannot acquire lock on file %q: %s", flockFile, err)
+		return nil, err
 	}
 
 	// Open table parts.
diff --git a/lib/storage/storage.go b/lib/storage/storage.go
index b077a2c0e..84d6880be 100644
--- a/lib/storage/storage.go
+++ b/lib/storage/storage.go
@@ -21,7 +21,6 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/memory"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/timerpool"
 	"github.com/VictoriaMetrics/fastcache"
-	"golang.org/x/sys/unix"
 )
 
 const maxRetentionMonths = 12 * 100
@@ -103,13 +102,10 @@ func OpenStorage(path string, retentionMonths int) (*Storage, error) {
 		return nil, fmt.Errorf("cannot create %q: %s", snapshotsPath, err)
 	}
 
-	flockFile := path + "/flock.lock"
-	flockF, err := os.Create(flockFile)
+	// Protect from concurrent opens.
+	flockF, err := fs.CreateFlockFile(path)
 	if err != nil {
-		return nil, fmt.Errorf("cannot create lock file %q: %s", flockFile, err)
-	}
-	if err := unix.Flock(int(flockF.Fd()), unix.LOCK_EX|unix.LOCK_NB); err != nil {
-		return nil, fmt.Errorf("cannot acquire lock on file %q: %s", flockFile, err)
+		return nil, err
 	}
 	s.flockF = flockF
 
diff --git a/lib/storage/table.go b/lib/storage/table.go
index 4acc27b0c..9a0cc3d6e 100644
--- a/lib/storage/table.go
+++ b/lib/storage/table.go
@@ -10,7 +10,6 @@ import (
 
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fs"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
-	"golang.org/x/sys/unix"
 )
 
 // table represents a single table with time series data.
@@ -84,13 +83,10 @@ func openTable(path string, retentionMonths int, getDeletedMetricIDs func() map[
 		return nil, fmt.Errorf("cannot create directory for table %q: %s", path, err)
 	}
 
-	flockFile := path + "/flock.lock"
-	flockF, err := os.Create(flockFile)
+	// Protect from concurrent opens.
+	flockF, err := fs.CreateFlockFile(path)
 	if err != nil {
-		return nil, fmt.Errorf("cannot create lock file %q: %s", flockFile, err)
-	}
-	if err := unix.Flock(int(flockF.Fd()), unix.LOCK_EX|unix.LOCK_NB); err != nil {
-		return nil, fmt.Errorf("cannot acquire lock on file %q: %s", flockFile, err)
+		return nil, err
 	}
 
 	// Create directories for small and big partitions if they don't exist yet.