ceremonyclient/pebble/vfs/file_lock_test.go

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2024-01-03 07:31:42 +00:00
// Copyright 2014 The LevelDB-Go and Pebble Authors. All rights reserved. Use
// of this source code is governed by a BSD-style license that can be found in
// the LICENSE file.
package vfs_test
import (
"bytes"
"flag"
"os"
"os/exec"
"testing"
"github.com/cockroachdb/pebble/vfs"
"github.com/stretchr/testify/require"
)
var lockFilename = flag.String("lockfile", "", "File to lock. A non-empty value implies a child process.")
func spawn(prog, filename string) ([]byte, error) {
return exec.Command(prog, "-lockfile", filename, "-test.v",
"-test.run=TestLock$").CombinedOutput()
}
// TestLock locks a file, spawns a second process that attempts to grab the
// lock to verify it fails.
// Then it closes the lock, and spawns a third copy to verify it can be
// relocked.
func TestLock(t *testing.T) {
child := *lockFilename != ""
var filename string
if child {
filename = *lockFilename
} else {
f, err := os.CreateTemp("", "golang-pebble-db-testlock-")
require.NoError(t, err)
filename = f.Name()
// NB: On Windows, locking will fail if the file is already open by the
// current process, so we close the lockfile here.
require.NoError(t, f.Close())
defer os.Remove(filename)
}
// Avoid truncating an existing, non-empty file.
fi, err := os.Stat(filename)
if err == nil && fi.Size() != 0 {
t.Fatalf("The file %s is not empty", filename)
}
t.Logf("Locking: %s", filename)
lock, err := vfs.Default.Lock(filename)
if err != nil {
t.Fatalf("Could not lock %s: %v", filename, err)
}
if !child {
t.Logf("Spawning child, should fail to grab lock.")
out, err := spawn(os.Args[0], filename)
if err == nil {
t.Fatalf("Attempt to grab open lock should have failed.\n%s", out)
}
if !bytes.Contains(out, []byte("Could not lock")) {
t.Fatalf("Child failed with unexpected output: %s", out)
}
t.Logf("Child failed to grab lock as expected.")
}
t.Logf("Unlocking %s", filename)
if err := lock.Close(); err != nil {
t.Fatalf("Could not unlock %s: %v", filename, err)
}
if !child {
t.Logf("Spawning child, should successfully grab lock.")
if out, err := spawn(os.Args[0], filename); err != nil {
t.Fatalf("Attempt to re-open lock should have succeeded: %v\n%s",
err, out)
}
t.Logf("Child grabbed lock.")
}
}
func TestLockSameProcess(t *testing.T) {
f, err := os.CreateTemp("", "pebble-testlocksameprocess-")
require.NoError(t, err)
filename := f.Name()
// NB: On Windows, locking will fail if the file is already open by the
// current process, so we close the lockfile here.
require.NoError(t, f.Close())
defer os.Remove(filename)
lock1, err := vfs.Default.Lock(filename)
require.NoError(t, err)
// Locking the file again from within the same process should fail.
// On Unix, Lock should detect the file in the global map of
// process-locked files.
// On Windows, locking will fail since the file is already open by the
// current process.
_, err = vfs.Default.Lock(filename)
require.Error(t, err)
require.NoError(t, lock1.Close())
}