// Previous sets the read pointer into the journal back by one entry.
func (j *Journal) Previous() (uint64, error) {
j.mu.Lock()
r := C.sd_journal_previous(j.cjournal)
j.mu.Unlock()
if r < 0 {
return uint64(r), fmt.Errorf("failed to iterate journal: %d", r)
}
return uint64(r), nil
}
func (s *journald) readLogs(logWatcher *logger.LogWatcher, config logger.ReadConfig) {
var j *C.sd_journal
var cmatch *C.char
var stamp C.uint64_t
var sinceUnixMicro uint64
var pipes [2]C.int
cursor := ""
defer close(logWatcher.Msg)
// Get a handle to the journal.
rc := C.sd_journal_open(&j, C.int(0))
if rc != 0 {
logWatcher.Err <- fmt.Errorf("error opening journal")
return
}
defer C.sd_journal_close(j)
// Remove limits on the size of data items that we'll retrieve.
rc = C.sd_journal_set_data_threshold(j, C.size_t(0))
if rc != 0 {
logWatcher.Err <- fmt.Errorf("error setting journal data threshold")
return
}
// Add a match to have the library do the searching for us.
cmatch = C.CString("CONTAINER_ID_FULL=" + s.vars["CONTAINER_ID_FULL"])
defer C.free(unsafe.Pointer(cmatch))
rc = C.sd_journal_add_match(j, unsafe.Pointer(cmatch), C.strlen(cmatch))
if rc != 0 {
logWatcher.Err <- fmt.Errorf("error setting journal match")
return
}
// If we have a cutoff time, convert it to Unix time once.
if !config.Since.IsZero() {
nano := config.Since.UnixNano()
sinceUnixMicro = uint64(nano / 1000)
}
if config.Tail > 0 {
lines := config.Tail
// Start at the end of the journal.
if C.sd_journal_seek_tail(j) < 0 {
logWatcher.Err <- fmt.Errorf("error seeking to end of journal")
return
}
if C.sd_journal_previous(j) < 0 {
logWatcher.Err <- fmt.Errorf("error backtracking to previous journal entry")
return
}
// Walk backward.
for lines > 0 {
// Stop if the entry time is before our cutoff.
// We'll need the entry time if it isn't, so go
// ahead and parse it now.
if C.sd_journal_get_realtime_usec(j, &stamp) != 0 {
break
} else {
// Compare the timestamp on the entry
// to our threshold value.
if sinceUnixMicro != 0 && sinceUnixMicro > uint64(stamp) {
break
}
}
lines--
// If we're at the start of the journal, or
// don't need to back up past any more entries,
// stop.
if lines == 0 || C.sd_journal_previous(j) <= 0 {
break
}
}
} else {
// Start at the beginning of the journal.
if C.sd_journal_seek_head(j) < 0 {
logWatcher.Err <- fmt.Errorf("error seeking to start of journal")
return
}
// If we have a cutoff date, fast-forward to it.
if sinceUnixMicro != 0 && C.sd_journal_seek_realtime_usec(j, C.uint64_t(sinceUnixMicro)) != 0 {
logWatcher.Err <- fmt.Errorf("error seeking to start time in journal")
return
}
if C.sd_journal_next(j) < 0 {
logWatcher.Err <- fmt.Errorf("error skipping to next journal entry")
return
}
}
cursor = s.drainJournal(logWatcher, config, j, "")
if config.Follow {
// Create a pipe that we can poll at the same time as the journald descriptor.
if C.pipe(&pipes[0]) == C.int(-1) {
logWatcher.Err <- fmt.Errorf("error opening journald close notification pipe")
} else {
s.followJournal(logWatcher, config, j, pipes, cursor)
}
}
return
}
func (s *journald) readLogs(logWatcher *logger.LogWatcher, config logger.ReadConfig) {
var j *C.sd_journal
var cmatch *C.char
var stamp C.uint64_t
var sinceUnixMicro uint64
var pipes [2]C.int
cursor := ""
// Get a handle to the journal.
rc := C.sd_journal_open(&j, C.int(0))
if rc != 0 {
logWatcher.Err <- fmt.Errorf("error opening journal")
close(logWatcher.Msg)
return
}
// If we end up following the log, we can set the journal context
// pointer and the channel pointer to nil so that we won't close them
// here, potentially while the goroutine that uses them is still
// running. Otherwise, close them when we return from this function.
following := false
defer func(pfollowing *bool) {
if !*pfollowing {
C.sd_journal_close(j)
close(logWatcher.Msg)
}
}(&following)
// Remove limits on the size of data items that we'll retrieve.
rc = C.sd_journal_set_data_threshold(j, C.size_t(0))
if rc != 0 {
logWatcher.Err <- fmt.Errorf("error setting journal data threshold")
return
}
// Add a match to have the library do the searching for us.
cmatch = C.CString("CONTAINER_ID_FULL=" + s.vars["CONTAINER_ID_FULL"])
defer C.free(unsafe.Pointer(cmatch))
rc = C.sd_journal_add_match(j, unsafe.Pointer(cmatch), C.strlen(cmatch))
if rc != 0 {
logWatcher.Err <- fmt.Errorf("error setting journal match")
return
}
// If we have a cutoff time, convert it to Unix time once.
if !config.Since.IsZero() {
nano := config.Since.UnixNano()
sinceUnixMicro = uint64(nano / 1000)
}
if config.Tail > 0 {
lines := config.Tail
// Start at the end of the journal.
if C.sd_journal_seek_tail(j) < 0 {
logWatcher.Err <- fmt.Errorf("error seeking to end of journal")
return
}
if C.sd_journal_previous(j) < 0 {
logWatcher.Err <- fmt.Errorf("error backtracking to previous journal entry")
return
}
// Walk backward.
for lines > 0 {
// Stop if the entry time is before our cutoff.
// We'll need the entry time if it isn't, so go
// ahead and parse it now.
if C.sd_journal_get_realtime_usec(j, &stamp) != 0 {
break
} else {
// Compare the timestamp on the entry
// to our threshold value.
if sinceUnixMicro != 0 && sinceUnixMicro > uint64(stamp) {
break
}
}
lines--
// If we're at the start of the journal, or
// don't need to back up past any more entries,
// stop.
if lines == 0 || C.sd_journal_previous(j) <= 0 {
break
}
}
} else {
// Start at the beginning of the journal.
if C.sd_journal_seek_head(j) < 0 {
logWatcher.Err <- fmt.Errorf("error seeking to start of journal")
return
}
// If we have a cutoff date, fast-forward to it.
if sinceUnixMicro != 0 && C.sd_journal_seek_realtime_usec(j, C.uint64_t(sinceUnixMicro)) != 0 {
logWatcher.Err <- fmt.Errorf("error seeking to start time in journal")
return
}
if C.sd_journal_next(j) < 0 {
logWatcher.Err <- fmt.Errorf("error skipping to next journal entry")
return
}
}
cursor = s.drainJournal(logWatcher, config, j, "")
if config.Follow {
// Allocate a descriptor for following the journal, if we'll
// need one. Do it here so that we can report if it fails.
if fd := C.sd_journal_get_fd(j); fd < C.int(0) {
logWatcher.Err <- fmt.Errorf("error opening journald follow descriptor: %q", C.GoString(C.strerror(-fd)))
} else {
// Create a pipe that we can poll at the same time as
// the journald descriptor.
if C.pipe(&pipes[0]) == C.int(-1) {
logWatcher.Err <- fmt.Errorf("error opening journald close notification pipe")
} else {
s.followJournal(logWatcher, config, j, pipes, cursor)
// Let followJournal handle freeing the journal context
// object and closing the channel.
following = true
}
}
}
return
}