Merge pull request #6633 from grondo/reslog-truncate-simple

truncate resource journal at configurable size

Author: mergify[bot]

doc/man5/flux-config-resource.rst

@@ -79,8 +79,14 @@ rediscover
    (optional) If true, force rediscovery of resources using HWLOC, rather
    then using the R and HWLOC XML from the enclosing instance.
 
-Note that updates to the resource table are ignored until the next Flux
-restart.
+journal-max
+   (optional) An integer containing the maximum number of resource eventlog
+   events held in the resource module for the ``resource.journal`` RPC. The
+   default is 100,000. This value takes immediate effect on a configuration
+   update.
+
+Note that, except where noted above, updates to the resource table are
+ignored until the next Flux restart.
 
 EXAMPLE
 =======

src/modules/resource/reslog.c

@@ -36,7 +36,8 @@ struct reslog {
     struct resource_ctx *ctx;
     zlist_t *pending;       // list of pending futures
     zlist_t *watchers;
-    json_t *eventlog;
+    zlistx_t *eventlog;
+    int journal_max;
     struct flux_msglist *consumers;
     flux_msg_handler_t **handlers;
 };
@@ -196,6 +197,45 @@ int reslog_sync (struct reslog *reslog)
     return 0;
 }
 
+/*  Truncate resource journal if needed to reslog->journal_max
+ */
+static int reslog_truncate (struct reslog *reslog)
+{
+    int rc = -1;
+    int count;
+    double timestamp;
+    json_t *event = NULL;
+
+    if ((count = zlistx_size (reslog->eventlog)) <= reslog->journal_max)
+        return 0;
+
+    /*  Detach events until count is decreased to max - 1.
+     *  Save timestamps for the truncate event.
+     */
+    while (count-- >= reslog->journal_max) {
+        event = zlistx_first (reslog->eventlog);
+        if (eventlog_entry_parse (event, &timestamp, NULL, NULL) < 0) {
+            /* Unlikely: failed to parse timestamp from first event, but
+             * timestamp of truncate event needs to come before any other
+             * event, so set it to a small value (not 0., because this will
+             * cause eventlog_entry_create() to use current timestamp.)
+             */
+            timestamp = 0.1;
+        }
+        zlistx_delete (reslog->eventlog, zlistx_cursor (reslog->eventlog));
+    }
+
+    /* Push truncate event onto front of list
+     */
+    if (!(event = eventlog_entry_create (timestamp, "truncate", NULL))
+        || !(zlistx_add_start (reslog->eventlog, event)))
+        goto out;
+    rc = 0;
+out:
+    json_decref (event);
+    return rc;
+}
+
 int reslog_post_pack (struct reslog *reslog,
                       const flux_msg_t *request,
                       double timestamp,
@@ -217,11 +257,12 @@ int reslog_post_pack (struct reslog *reslog,
     va_end (ap);
     if (!event)
         return -1;
-    if (json_array_append (reslog->eventlog, event) < 0) {
-        json_decref (event);
+    if (!zlistx_add_end (reslog->eventlog, event)) {
         errno = ENOMEM;
         return -1;
     }
+    if (reslog_truncate (reslog) < 0)
+        flux_log_error (h, "failed to truncate eventlog");
     if ((flags & EVENT_NO_COMMIT)) {
         if (!(f = flux_future_create (NULL, NULL)))
             goto error;
@@ -299,11 +340,11 @@ int reslog_add_callback (struct reslog *reslog, reslog_cb_f cb, void *arg)
 static bool send_backlog (struct reslog *reslog, const flux_msg_t *msg)
 {
     flux_t *h = reslog->ctx->h;
-    size_t index;
-    json_t *entry;
-    json_array_foreach (reslog->eventlog, index, entry) {
+    json_t *entry = zlistx_first (reslog->eventlog);
+    while (entry) {
         if (notify_one_consumer (reslog, msg, entry) < 0)
             goto error;
+        entry = zlistx_next (reslog->eventlog);
     }
     if (flux_respond_pack (h, msg, "{s:[]}", "events") < 0) // delimiter
         goto error;
@@ -398,34 +439,64 @@ void reslog_destroy (struct reslog *reslog)
             flux_msglist_destroy (reslog->consumers);
         }
         zlist_destroy (&reslog->watchers);
-        json_decref (reslog->eventlog);
+        zlistx_destroy (&reslog->eventlog);
         free (reslog);
         errno = saved_errno;
     }
 }
 
-struct reslog *reslog_create (struct resource_ctx *ctx, json_t *eventlog)
+static void entry_destructor (void **item)
+{
+    if (*item) {
+        json_decref (*item);
+        *item = NULL;
+    }
+}
+
+static void *entry_duplicator (const void *item)
+{
+    return json_incref ((json_t *) item);
+}
+
+void reslog_set_journal_max (struct reslog *reslog, int max)
+{
+    if (reslog) {
+        reslog->journal_max = max;
+        if (reslog_truncate (reslog) < 0)
+            flux_log_error (reslog->ctx->h,
+                            "resource eventlog truncation failed");
+    }
+}
+
+struct reslog *reslog_create (struct resource_ctx *ctx,
+                              json_t *eventlog,
+                              int journal_max)
 {
     struct reslog *reslog;
 
     if (!(reslog = calloc (1, sizeof (*reslog))))
         return NULL;
     reslog->ctx = ctx;
+    reslog->journal_max = journal_max;
     if (!(reslog->pending = zlist_new ())
         || !(reslog->watchers = zlist_new ()))
         goto nomem;
     zlist_comparefn (reslog->watchers, watcher_compare);
-    if (!(reslog->eventlog = json_array ()))
+    if (!(reslog->eventlog = zlistx_new ()))
         goto nomem;
+    zlistx_set_destructor (reslog->eventlog, entry_destructor);
+    zlistx_set_duplicator (reslog->eventlog, entry_duplicator);
     if (eventlog) {
         size_t index;
         json_t *entry;
         json_array_foreach (eventlog, index, entry) {
             // historical resource-define events are not helpful
             if (match_event (entry, "resource-define"))
                 continue;
-            if (json_array_append (reslog->eventlog, entry) < 0)
+            if (!zlistx_add_end (reslog->eventlog, entry))
                 goto nomem;
+            if (reslog_truncate (reslog) < 0)
+                flux_log_error (ctx->h, "eventlog truncate failed");
         }
     }
     if (!(reslog->consumers = flux_msglist_create ()))

src/modules/resource/reslog.h

@@ -22,9 +22,13 @@ typedef void (*reslog_cb_f)(struct reslog *reslog,
                             json_t *context,
                             void *arg);
 
-struct reslog *reslog_create (struct resource_ctx *ctx, json_t *eventlog);
+struct reslog *reslog_create (struct resource_ctx *ctx,
+                              json_t *eventlog,
+                              int journal_max);
 void reslog_destroy (struct reslog *reslog);
 
+void reslog_set_journal_max (struct reslog *reslog, int max);
+
 /* Post an event to the eventlog.  This function returns immediately,
  * and the commit to the eventlog completes asynchronously.
  * If 'request' is non-NULL, a success/fail response is sent upon commit

src/modules/resource/resource.c

@@ -61,7 +61,11 @@
  * rediscover = false
  *   Force rediscovery of local resources via hwloc. Do not fetch R or hwloc
  *   XML from the enclosing instance.
+ *
+ * journal-max = 100000
+ *   Maximum size allowed of the resource journal before it is truncated.
  */
+
 static int parse_config (struct resource_ctx *ctx,
                          const flux_conf_t *conf,
                          struct resource_config *rconfig,
@@ -75,12 +79,13 @@ static int parse_config (struct resource_ctx *ctx,
     int norestrict = 0;
     int no_update_watch = 0;
     int rediscover = 0;
+    int journal_max = 100000;
     json_t *o = NULL;
     json_t *config = NULL;
 
     if (flux_conf_unpack (conf,
                           &error,
-                          "{s?{s?s s?s s?o s?s s?b s?b s?b s?b !}}",
+                          "{s?{s?s s?s s?o s?s s?b s?b s?b s?b s?i !}}",
                           "resource",
                             "path", &path,
                             "scheduling", &scheduling_path,
@@ -89,7 +94,8 @@ static int parse_config (struct resource_ctx *ctx,
                             "norestrict", &norestrict,
                             "noverify", &noverify,
                             "no-update-watch", &no_update_watch,
-                            "rediscover", &rediscover) < 0) {
+                            "rediscover", &rediscover,
+                            "journal-max", &journal_max) < 0) {
         errprintf (errp,
                    "error parsing [resource] configuration: %s",
                    error.text);
@@ -146,6 +152,7 @@ static int parse_config (struct resource_ctx *ctx,
         }
     }
     if (rconfig) {
+        rconfig->journal_max = journal_max;
         rconfig->exclude_idset = exclude;
         rconfig->noverify = noverify ? true : false;
         rconfig->norestrict = norestrict ? true : false;
@@ -171,13 +178,15 @@ static void config_reload_cb (flux_t *h,
     const flux_conf_t *conf;
     flux_error_t error;
     const char *errstr = NULL;
+    struct resource_config config = {0};
 
     if (flux_conf_reload_decode (msg, &conf) < 0)
         goto error;
-    if (parse_config (ctx, conf, NULL, &error) < 0) {
+    if (parse_config (ctx, conf, &config, &error) < 0) {
         errstr = error.text;
         goto error;
     }
+    reslog_set_journal_max (ctx->reslog, config.journal_max);
     if (flux_set_conf (h, flux_conf_incref (conf)) < 0) {
         errstr = "error updating cached configuration";
         goto error;
@@ -372,7 +381,7 @@ int mod_main (flux_t *h, int argc, char **argv)
          */
         if (upgrade_eventlog (h, &eventlog) < 0)
             goto error;
-        if (!(ctx->reslog = reslog_create (ctx, eventlog)))
+        if (!(ctx->reslog = reslog_create (ctx, eventlog, config.journal_max)))
             goto error;
         if (!(ctx->acquire = acquire_create (ctx)))
             goto error;

src/modules/resource/resource.h

@@ -19,6 +19,7 @@ struct resource_config {
     bool norestrict;
     bool no_update_watch;
     bool monitor_force_up;
+    int journal_max;
 };
 
 struct resource_ctx {

t/t2355-resource-journal.t

@@ -158,7 +158,55 @@ test_expect_success 'last event: resource-define method=kvs' '
 	jq -e ".name == \"resource-define\"" restartlog.3 &&
 	jq -e ".context.method == \"kvs\"" restartlog.3
 '
-
+test_expect_success 'ensure all ranks are undrained' '
+	ranks=$(flux resource status -no {ranks} -s drain) &&
+	if test -n "$ranks"; then
+	    flux resource undrain $ranks
+	fi
+'
+test_expect_success 'capture eventlog before truncation' '
+	flux resource eventlog -H &&
+	flux resource eventlog -f json > eventlog.pre.out
+'
+test_expect_success 'set a journal size limit 1 less than current entries' '
+	limit=$(($(flux resource eventlog | wc -l) - 1)) &&
+	test_debug "echo limiting resource.journal to $limit entries" &&
+	echo resource.journal-max=$limit | flux config load
+'
+test_expect_success 'eventlog is now truncated' '
+	flux resource eventlog -H &&
+	flux resource eventlog -f json > eventlog.trunc
+'
+test_expect_success 'truncated eventlog has expected number of entries' '
+	test_debug "wc -l eventlog.trunc" &&
+	test $(wc -l < eventlog.trunc) -eq $limit
+'
+test_expect_success '1st event is a truncate event' '
+	head -1 eventlog.trunc > eventlog.trunc.1 &&
+	jq -e ".name == \"truncate\"" eventlog.trunc.1
+'
+test_expect_success 'cause another event to be posted to the eventlog' '
+	flux resource drain 0
+'
+test_expect_success '1st event is still a truncate event' '
+	flux resource eventlog -H &&
+	flux resource eventlog -f json > eventlog2.trunc &&
+	head -1 eventlog2.trunc | jq -e ".name == \"truncate\""
+'
+test_expect_success 'truncated eventlog has expected number of entries' '
+	test $(wc -l < eventlog2.trunc) -eq $limit
+'
+test_expect_success 'cause another event to be posted to the eventlog' '
+	flux resource undrain 0
+'
+test_expect_success '1st event is still a truncate event' '
+	flux resource eventlog -H &&
+	flux resource eventlog -f json > eventlog3.trunc &&
+	head -1 eventlog3.trunc | jq -e ".name == \"truncate\""
+'
+test_expect_success 'truncated eventlog has expected number of entries' '
+	test $(wc -l < eventlog3.trunc) -eq $limit
+'
 test_expect_success 'reload the scheduler' '
 	flux module load sched-simple
 '