diff options
Diffstat (limited to 'compiler_wrapper/rusage_flag.go')
-rw-r--r-- | compiler_wrapper/rusage_flag.go | 52 |
1 files changed, 43 insertions, 9 deletions
diff --git a/compiler_wrapper/rusage_flag.go b/compiler_wrapper/rusage_flag.go index 2a3768c1..690308b2 100644 --- a/compiler_wrapper/rusage_flag.go +++ b/compiler_wrapper/rusage_flag.go @@ -18,6 +18,26 @@ func getRusageLogFilename(env env) string { return value } +func lockFileExclusive(fd uintptr) error { + maxTries := 100 + for i := 0; i < maxTries; i++ { + const seekSet = 0 + err := syscall.FcntlFlock(fd, syscall.F_SETLKW, &syscall.Flock_t{ + Type: syscall.F_WRLCK, + Whence: seekSet, + Start: 0, + Len: 0, + }) + if err == nil { + return nil + } + if err != syscall.EINTR { + return fmt.Errorf("locking file: %v", err) + } + } + return fmt.Errorf("locking file failed after %d tries", maxTries) +} + func logRusage(env env, logFileName string, compilerCmd *command) (exitCode int, err error) { rusageBefore := syscall.Rusage{} if err := syscall.Getrusage(syscall.RUSAGE_CHILDREN, &rusageBefore); err != nil { @@ -49,21 +69,35 @@ func logRusage(env env, logFileName string, compilerCmd *command) (exitCode int, if err := os.MkdirAll(filepath.Dir(logFileName), 0777); err != nil { return 0, wrapErrorwithSourceLocf(err, "error creating rusage log directory %s", logFileName) } + + timeUnit := float64(time.Second) + data := fmt.Sprintf("%.5f : %.5f : %.5f : %d : %s : %s\n", + float64(elapsedRealTime)/timeUnit, float64(elapsedUserTime)/timeUnit, float64(elapsedSysTime)/timeUnit, + maxMemUsed, absCompilerPath, + strings.Join(append([]string{filepath.Base(absCompilerPath)}, compilerCmd.Args...), " ")) + // Note: using file mode 0666 so that a root-created log is writable by others. logFile, err := os.OpenFile(logFileName, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0666) if err != nil { - return 0, wrapErrorwithSourceLocf(err, "error creating rusage logfile %s", logFileName) + return 0, wrapErrorwithSourceLocf(err, "creating rusage logfile %s", logFileName) } - timeUnit := float64(time.Second) - if _, err := fmt.Fprintf(logFile, "%.5f : %.5f : %.5f : %d : %s : %s\n", - float64(elapsedRealTime)/timeUnit, float64(elapsedUserTime)/timeUnit, float64(elapsedSysTime)/timeUnit, - maxMemUsed, absCompilerPath, - strings.Join(append([]string{filepath.Base(absCompilerPath)}, compilerCmd.Args...), " ")); err != nil { + + // O_APPEND's atomicity guarantees are only for writes up to a certain size. If we don't + // lock the file, we might end up with corrupted records. + // + // Note that Close()'ing the file releases all associated locks. + if err := lockFileExclusive(logFile.Fd()); err != nil { _ = logFile.Close() - return 0, wrapErrorwithSourceLocf(err, "error writing rusage logfile %s", logFileName) + return 0, wrapErrorwithSourceLocf(err, "locking rusage logfile %s: %v", logFileName, err) + } + + _, err = logFile.WriteString(data) + closeErr := logFile.Close() + if err != nil { + return 0, wrapErrorwithSourceLocf(err, "writing to rusage logfile %s: %v", logFileName, err) } - if err := logFile.Close(); err != nil { - return 0, wrapErrorwithSourceLocf(err, "error closing rusage logfile %s", logFileName) + if closeErr != nil { + return 0, wrapErrorwithSourceLocf(err, "closing rusage logfile %s: %v", logFileName, closeErr) } return exitCode, nil |