Synchronize file rotation
Create a lock file during log rotation so that multiple processes won't
step on each other.
Test: Run `while true; do get_build_var TARGET_PRODUCT; done` in parallel
Test: m blueprint_tools
Change-Id: I7144cd42aca47c694487ddae44713f82665ed81e
diff --git a/ui/logger/logger.go b/ui/logger/logger.go
index 7d9687b..15c413d 100644
--- a/ui/logger/logger.go
+++ b/ui/logger/logger.go
@@ -38,6 +38,7 @@
"path/filepath"
"strconv"
"sync"
+ "syscall"
)
type Logger interface {
@@ -93,10 +94,19 @@
// existing files to <filename>.#.<ext>, keeping up to maxCount files.
// <filename>.1.<ext> is the most recent backup, <filename>.2.<ext> is the
// second most recent backup, etc.
-//
-// TODO: This function is not guaranteed to be atomic, if there are multiple
-// users attempting to do the same operation, the result is undefined.
func CreateFileWithRotation(filename string, maxCount int) (*os.File, error) {
+ lockFileName := filepath.Join(filepath.Dir(filename), ".lock_"+filepath.Base(filename))
+ lockFile, err := os.OpenFile(lockFileName, os.O_RDWR|os.O_CREATE, 0666)
+ if err != nil {
+ return nil, err
+ }
+ defer lockFile.Close()
+
+ err = syscall.Flock(int(lockFile.Fd()), syscall.LOCK_EX)
+ if err != nil {
+ return nil, err
+ }
+
if _, err := os.Lstat(filename); err == nil {
ext := filepath.Ext(filename)
basename := filename[:len(filename)-len(ext)]
diff --git a/ui/logger/logger_test.go b/ui/logger/logger_test.go
index 0f88ab3..dc6f2e9 100644
--- a/ui/logger/logger_test.go
+++ b/ui/logger/logger_test.go
@@ -67,7 +67,7 @@
t.Fatalf("Failed to read dir: %v", err)
}
sort.Strings(names)
- expected := []string{"build.1.log", "build.2.log", "build.3.log", "build.log"}
+ expected := []string{".lock_build.log", "build.1.log", "build.2.log", "build.3.log", "build.log"}
if !reflect.DeepEqual(names, expected) {
t.Errorf("File list does not match.")
t.Errorf(" got: %v", names)