broker: use module stats for log debug stuff

Problem: broker attributes reflect live usage stats of the
log ring buffer for testing, but in other parts of the broker
we have migrated that sort of stuff to the stats.get RPC.

Add RPC handler for stats object.
Drop log-count and log-ring-used broker attributes.
Update dmesg sharness test.
Drop those attributes from flux-broker-attributes(7).

Author: garlick

doc/man7/flux-broker-attributes.rst

@@ -211,16 +211,10 @@ tbon.tcp_user_timeout
 LOGGING
 =======
 
-log-ring-used
-   The number of log entries currently stored in the ring buffer.
-
 log-ring-size [Updates: C, R]
    The maximum number of log entries that can be stored in the ring buffer.
    Default: ``1024``.
 
-log-count
-   The number of log entries ever stored in the ring buffer.
-
 log-forward-level [Updates: C, R]
    Log entries at :linux:man3:`syslog` level at or below this value
    are forwarded to rank zero for permanent capture.  Default ``7``

src/broker/log.c

@@ -264,10 +264,6 @@ static int attr_get_log (const char *name, const char **val, void *arg)
         *val = logbuf->stderr_mode == MODE_LEADER ? "leader" : "local";
     else if (!strcmp (name, "log-ring-size"))
         *val = int_to_string (logbuf->ring_size);
-    else if (!strcmp (name, "log-ring-used"))
-        *val = int_to_string (zlist_size (logbuf->buf));
-    else if (!strcmp (name, "log-count"))
-        *val = int_to_string (logbuf->seq);
     else if (!strcmp (name, "log-filename"))
         *val = logbuf->filename;
     else if (!strcmp (name, "log-level"))
@@ -360,12 +356,6 @@ static int logbuf_register_attrs (logbuf_t *logbuf, attr_t *attrs)
     if (attr_add_active (attrs, "log-ring-size", 0,
                          attr_get_log, attr_set_log, logbuf) < 0)
         goto done;
-    if (attr_add_active (attrs, "log-ring-used", 0,
-                         attr_get_log, NULL, logbuf) < 0)
-        goto done;
-    if (attr_add_active (attrs, "log-count", 0,
-                         attr_get_log, NULL, logbuf) < 0)
-        goto done;
     rc = 0;
 done:
     return rc;
@@ -571,12 +561,29 @@ static void cancel_request_cb (flux_t *h,
     flux_msglist_cancel (h, logbuf->followers, msg);
 }
 
+static void stats_request_cb (flux_t *h,
+                              flux_msg_handler_t *mh,
+                              const flux_msg_t *msg,
+                              void *arg)
+{
+    logbuf_t *logbuf = arg;
+
+    if (flux_respond_pack (h,
+                           msg,
+                           "{s:i s:i}",
+                           "ring-used", (int)zlist_size (logbuf->buf),
+                           "count", logbuf->seq) < 0)
+        flux_log_error (h, "error responding to log.stats.get");
+}
+
+
 static const struct flux_msg_handler_spec htab[] = {
     { FLUX_MSGTYPE_REQUEST, "log.append",         append_request_cb, 0 },
     { FLUX_MSGTYPE_REQUEST, "log.clear",          clear_request_cb, 0 },
     { FLUX_MSGTYPE_REQUEST, "log.dmesg",          dmesg_request_cb, 0 },
     { FLUX_MSGTYPE_REQUEST, "log.disconnect",     disconnect_request_cb, 0 },
     { FLUX_MSGTYPE_REQUEST, "log.cancel",         cancel_request_cb, 0 },
+    { FLUX_MSGTYPE_REQUEST, "log.stats.get",      stats_request_cb, 0 },
     FLUX_MSGHANDLER_TABLE_END,
 };
 

t/t0009-dmesg.t

@@ -9,16 +9,16 @@ waitfile="${SHARNESS_TEST_SRCDIR}/scripts/waitfile.lua"
 
 test_under_flux 4 minimal
 
-test_expect_success 'flux getattr log-count counts log messages' '
-	OLD_VAL=`flux getattr log-count` &&
+test_expect_success 'module stats --parse count log counts log messages' '
+	OLD_VAL=$(flux module stats --parse count log) &&
 	flux logger hello &&
-	NEW_VAL=`flux getattr log-count` &&
+	NEW_VAL=$(flux module stats --parse count log) &&
 	test "${OLD_VAL}" -lt "${NEW_VAL}"
 '
-test_expect_success 'flux getattr log-ring-used counts log messages' '
-	OLD_VAL=`flux getattr log-ring-used` &&
+test_expect_success 'module stats --parse ring-used log counts log messages' '
+	OLD_VAL=$(flux module stats --parse ring-used log) &&
 	flux logger hello &&
-	NEW_VAL=`flux getattr log-ring-used` &&
+	NEW_VAL=$(flux module stats --parse ring-used log) &&
 	test "${OLD_VAL}" -lt "${NEW_VAL}"
 '
 test_expect_success 'flux dmesg -C clears ring buffer' '