journal: Serialize __MONOTONIC_TIMESTAMP metadata field as well

Otherwise the forwarded journals won't have any monotonic timestamps.

src/journal/journald-server.c

@@ -20,6 +20,7 @@
 #include "conf-parser.h"
 #include "creds-util.h"
 #include "dirent-util.h"
+#include "event-util.h"
 #include "extract-word.h"
 #include "fd-util.h"
 #include "fileio.h"
@@ -932,24 +933,19 @@ static void server_write_to_journal(
                 uid_t uid,
                 const struct iovec *iovec,
                 size_t n,
+                const dual_timestamp *ts,
                 int priority) {
 
         bool vacuumed = false;
-        struct dual_timestamp ts;
         JournalFile *f;
         int r;
 
         assert(s);
         assert(iovec);
         assert(n > 0);
+        assert(ts);
 
-        /* Get the closest, linearized time we have for this log event from the event loop. (Note that we do not use
-         * the source time, and not even the time the event was originally seen, but instead simply the time we started
-         * processing it, as we want strictly linear ordering in what we write out.) */
-        assert_se(sd_event_now(s->event, CLOCK_REALTIME, &ts.realtime) >= 0);
-        assert_se(sd_event_now(s->event, CLOCK_MONOTONIC, &ts.monotonic) >= 0);
-
-        if (ts.realtime < s->last_realtime_clock) {
+        if (ts->realtime < s->last_realtime_clock) {
                 /* When the time jumps backwards, let's immediately rotate. Of course, this should not happen during
                  * regular operation. However, when it does happen, then we should make sure that we start fresh files
                  * to ensure that the entries in the journal files are strictly ordered by time, in order to ensure
@@ -983,11 +979,11 @@ static void server_write_to_journal(
                         return;
         }
 
-        s->last_realtime_clock = ts.realtime;
+        s->last_realtime_clock = ts->realtime;
 
         r = journal_file_append_entry(
                         f,
-                        &ts,
+                        ts,
                         /* boot_id= */ NULL,
                         iovec, n,
                         &s->seqnum->seqnum,
@@ -1019,7 +1015,7 @@ static void server_write_to_journal(
         log_debug_errno(r, "Retrying write.");
         r = journal_file_append_entry(
                         f,
-                        &ts,
+                        ts,
                         /* boot_id= */ NULL,
                         iovec, n,
                         &s->seqnum->seqnum,
@@ -1188,9 +1184,15 @@ static void server_dispatch_message_real(
         else
                 journal_uid = 0;
 
-        (void) server_forward_socket(s, iovec, n, priority);
+        /* Get the closest, linearized time we have for this log event from the event loop. (Note that we do
+         * not use the source time, and not even the time the event was originally seen, but instead simply
+         * the time we started processing it, as we want strictly linear ordering in what we write out.) */
+        struct dual_timestamp ts;
+        event_dual_timestamp_now(s->event, &ts);
+
+        (void) server_forward_socket(s, iovec, n, &ts, priority);
 
-        server_write_to_journal(s, journal_uid, iovec, n, priority);
+        server_write_to_journal(s, journal_uid, iovec, n, &ts, priority);
 }
 
 void server_driver_message(Server *s, pid_t object_pid, const char *message_id, const char *format, ...) {

src/journal/journald-socket.c

@@ -70,6 +70,7 @@ int server_forward_socket(
                 Server *s,
                 const struct iovec *iovec,
                 size_t n_iovec,
+                const dual_timestamp *ts,
                 int priority) {
 
         _cleanup_free_ struct iovec *iov_alloc = NULL;
@@ -81,6 +82,7 @@ int server_forward_socket(
         assert(s);
         assert(iovec);
         assert(n_iovec > 0);
+        assert(ts);
 
         if (LOG_PRI(priority) > s->max_level_socket)
                 return 0;
@@ -90,8 +92,8 @@ int server_forward_socket(
                 return r;
 
         /* We need a newline after each iovec + 4 for each we have to serialize in a binary safe way
-         * + 1 for the final __REALTIME_TIMESTAMP metadata field. */
-        size_t n = n_iovec * 5 + 1;
+         * + 2 for the final __REALTIME_TIMESTAMP and __MONOTONIC_TIMESTAMP metadata fields. */
+        size_t n = n_iovec * 5 + 2;
 
         if (n < ALLOCA_MAX / (sizeof(struct iovec) + sizeof(le64_t)) / 2) {
                 iov = newa(struct iovec, n);
@@ -139,11 +141,15 @@ int server_forward_socket(
                 iov[iov_idx++] = nl;
         }
 
-        /* Synthesise __REALTIME_TIMESTAMP as the last argument so systemd-journal-upload can receive these
-         * export messages. */
-        char buf[STRLEN("__REALTIME_TIMESTAMP=") + DECIMAL_STR_MAX(usec_t) + 2];
-        xsprintf(buf, "__REALTIME_TIMESTAMP="USEC_FMT"\n\n", now(CLOCK_REALTIME));
-        iov[iov_idx++] = IOVEC_MAKE_STRING(buf);
+        /* Synthesise __REALTIME_TIMESTAMP and __MONOTONIC_TIMESTAMP as the last arguments so
+         * systemd-journal-upload can receive these export messages. */
+        char realtime_buf[STRLEN("__REALTIME_TIMESTAMP=") + DECIMAL_STR_MAX(usec_t) + 1];
+        xsprintf(realtime_buf, "__REALTIME_TIMESTAMP="USEC_FMT"\n", ts->realtime);
+        iov[iov_idx++] = IOVEC_MAKE_STRING(realtime_buf);
+
+        char monotonic_buf[STRLEN("__MONOTONIC_TIMESTAMP=") + DECIMAL_STR_MAX(usec_t) + 2];
+        xsprintf(monotonic_buf, "__MONOTONIC_TIMESTAMP="USEC_FMT"\n\n", ts->monotonic);
+        iov[iov_idx++] = IOVEC_MAKE_STRING(monotonic_buf);
 
         if (writev(s->forward_socket_fd, iov, iov_idx) < 0) {
                 log_debug_errno(errno, "Failed to forward log message over socket: %m");

src/journal/journald-socket.h

@@ -4,4 +4,4 @@
 #include "journald-server.h"
 #include "socket-util.h"
 
-int server_forward_socket(Server *s, const struct iovec *iovec, size_t n, int priority);
+int server_forward_socket(Server *s, const struct iovec *iovec, size_t n, const dual_timestamp *ts, int priority);

src/libsystemd/sd-event/event-util.c

@@ -168,3 +168,12 @@ int event_add_child_pidref(
 
         return sd_event_add_child(e, s, pid->pid, options, callback, userdata);
 }
+
+dual_timestamp* event_dual_timestamp_now(sd_event *e, dual_timestamp *ts) {
+        assert(e);
+        assert(ts);
+
+        assert_se(sd_event_now(e, CLOCK_REALTIME, &ts->realtime) >= 0);
+        assert_se(sd_event_now(e, CLOCK_MONOTONIC, &ts->monotonic) >= 0);
+        return ts;
+}

src/libsystemd/sd-event/event-util.h

@@ -36,3 +36,5 @@ static inline int event_source_disable(sd_event_source *s) {
 int event_add_time_change(sd_event *e, sd_event_source **ret, sd_event_io_handler_t callback, void *userdata);
 
 int event_add_child_pidref(sd_event *e, sd_event_source **s, const PidRef *pid, int options, sd_event_child_handler_t callback, void *userdata);
+
+dual_timestamp* event_dual_timestamp_now(sd_event *e, dual_timestamp *ts);