prometheus/fileutil/flock_test.go

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// Copyright 2016 The Prometheus Authors
// 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
//
// http://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 fileutil
import (
"os"
"path/filepath"
"testing"
"github.com/prometheus/tsdb/testutil"
)
func TestLocking(t *testing.T) {
dir := testutil.NewTemporaryDirectory("test_flock", t)
defer dir.Close()
fileName := filepath.Join(dir.Path(), "LOCK")
if _, err := os.Stat(fileName); err == nil {
t.Fatalf("File %q unexpectedly exists.", fileName)
}
lock, existed, err := Flock(fileName)
if err != nil {
t.Fatalf("Error locking file %q: %s", fileName, err)
}
if existed {
t.Errorf("File %q reported as existing during locking.", fileName)
}
// File must now exist.
if _, err = os.Stat(fileName); err != nil {
t.Errorf("Could not stat file %q expected to exist: %s", fileName, err)
}
// Try to lock again.
lockedAgain, existed, err := Flock(fileName)
if err == nil {
t.Fatalf("File %q locked twice.", fileName)
}
if lockedAgain != nil {
t.Error("Unsuccessful locking did not return nil.")
}
if !existed {
t.Errorf("Existing file %q not recognized.", fileName)
}
if err := lock.Release(); err != nil {
t.Errorf("Error releasing lock for file %q: %s", fileName, err)
}
// File must still exist.
if _, err = os.Stat(fileName); err != nil {
t.Errorf("Could not stat file %q expected to exist: %s", fileName, err)
}
// Lock existing file.
lock, existed, err = Flock(fileName)
if err != nil {
t.Fatalf("Error locking file %q: %s", fileName, err)
}
if !existed {
t.Errorf("Existing file %q not recognized.", fileName)
}
if err := lock.Release(); err != nil {
t.Errorf("Error releasing lock for file %q: %s", fileName, err)
}
}