func (s *journald) drainJournal(logWatcher *logger.LogWatcher, config logger.ReadConfig, j *C.sd_journal, oldCursor string) string {
var msg, cursor *C.char
var length C.size_t
var stamp C.uint64_t
var priority C.int
// Walk the journal from here forward until we run out of new entries.
drain:
for {
// Try not to send a given entry twice.
if oldCursor != "" {
ccursor := C.CString(oldCursor)
defer C.free(unsafe.Pointer(ccursor))
for C.sd_journal_test_cursor(j, ccursor) > 0 {
if C.sd_journal_next(j) <= 0 {
break drain
}
}
}
// Read and send the logged message, if there is one to read.
i := C.get_message(j, &msg, &length)
if i != -C.ENOENT && i != -C.EADDRNOTAVAIL {
// Read the entry's timestamp.
if C.sd_journal_get_realtime_usec(j, &stamp) != 0 {
break
}
// Set up the time and text of the entry.
timestamp := time.Unix(int64(stamp)/1000000, (int64(stamp)%1000000)*1000)
line := append(C.GoBytes(unsafe.Pointer(msg), C.int(length)), "\n"...)
// Recover the stream name by mapping
// from the journal priority back to
// the stream that we would have
// assigned that value.
source := ""
if C.get_priority(j, &priority) != 0 {
source = ""
} else if priority == C.int(journal.PriErr) {
source = "stderr"
} else if priority == C.int(journal.PriInfo) {
source = "stdout"
}
// Send the log message.
cid := s.vars["CONTAINER_ID_FULL"]
logWatcher.Msg <- &logger.Message{ContainerID: cid, Line: line, Source: source, Timestamp: timestamp}
}
// If we're at the end of the journal, we're done (for now).
if C.sd_journal_next(j) <= 0 {
break
}
}
retCursor := ""
if C.sd_journal_get_cursor(j, &cursor) == 0 {
retCursor = C.GoString(cursor)
C.free(unsafe.Pointer(cursor))
}
return retCursor
}
// TestCursor may be used to check whether the current position in the journal matches the specified cursor. This is useful since cursor strings do not uniquely identify an entry: the same entry might be referred to by multiple different cursor strings, and hence string comparing cursors is not possible. Use this call to verify after an invocation of SeekCursor whether the entry being sought to was actually found in the journal or the next closest entry was used instead.
func (j *Journal) TestCursor(cursor string) (bool, error) {
ccursor := C.CString(cursor)
defer C.free(unsafe.Pointer(ccursor))
j.mu.Lock()
r := C.sd_journal_test_cursor(j.cjournal, ccursor)
j.mu.Unlock()
// testing failed if negative zero
if r < 0 {
return false, fmt.Errorf("failed to test cursor '%s' for seek accuracy: %d", cursor, r)
}
// if 0, it sought to the next closest position
if r == 0 {
return false, nil
}
// if positive, it sought to the exact position
return true, nil
}
func (s *journald) drainJournal(logWatcher *logger.LogWatcher, config logger.ReadConfig, j *C.sd_journal, oldCursor string) string {
var msg, data, cursor *C.char
var length C.size_t
var stamp C.uint64_t
var priority C.int
// Walk the journal from here forward until we run out of new entries.
drain:
for {
// Try not to send a given entry twice.
if oldCursor != "" {
ccursor := C.CString(oldCursor)
defer C.free(unsafe.Pointer(ccursor))
for C.sd_journal_test_cursor(j, ccursor) > 0 {
if C.sd_journal_next(j) <= 0 {
break drain
}
}
}
// Read and send the logged message, if there is one to read.
i := C.get_message(j, &msg, &length)
if i != -C.ENOENT && i != -C.EADDRNOTAVAIL {
// Read the entry's timestamp.
if C.sd_journal_get_realtime_usec(j, &stamp) != 0 {
break
}
// Set up the time and text of the entry.
timestamp := time.Unix(int64(stamp)/1000000, (int64(stamp)%1000000)*1000)
line := append(C.GoBytes(unsafe.Pointer(msg), C.int(length)), "\n"...)
// Recover the stream name by mapping
// from the journal priority back to
// the stream that we would have
// assigned that value.
source := ""
if C.get_priority(j, &priority) != 0 {
source = ""
} else if priority == C.int(journal.PriErr) {
source = "stderr"
} else if priority == C.int(journal.PriInfo) {
source = "stdout"
}
// Retrieve the values of any variables we're adding to the journal.
attrs := make(map[string]string)
C.sd_journal_restart_data(j)
for C.get_attribute_field(j, &data, &length) > C.int(0) {
kv := strings.SplitN(C.GoStringN(data, C.int(length)), "=", 2)
attrs[kv[0]] = kv[1]
}
if len(attrs) == 0 {
attrs = nil
}
// Send the log message.
logWatcher.Msg <- &logger.Message{
Line: line,
Source: source,
Timestamp: timestamp.In(time.UTC),
Attrs: attrs,
}
}
// If we're at the end of the journal, we're done (for now).
if C.sd_journal_next(j) <= 0 {
break
}
}
retCursor := ""
if C.sd_journal_get_cursor(j, &cursor) == 0 {
retCursor = C.GoString(cursor)
C.free(unsafe.Pointer(cursor))
}
return retCursor
}
