kvs: use zhashx for transaction_requests

Problem: In the kvsroot data structure, a zhash_t is used for
transaction requests.  A zhashx_t is preferred in flux-core
nowadays because it does not have as large of a initial memory
footprint.

Convert transaction_requests from a zhash_t to zhashx_t.

Author: chu11

src/modules/kvs/kvs.c

@@ -1234,7 +1234,7 @@ static int heartbeat_root_cb (struct kvsroot *root, void *arg)
 
     if (root->remove) {
         if (!zlist_size (root->wait_version_list)
-            && !zhash_size (root->transaction_requests)
+            && !zhashx_size (root->transaction_requests)
             && !kvstxn_mgr_ready_transaction_count (root->ktm)) {
 
             if (event_unsubscribe (ctx, root->ns_name) < 0)
@@ -1252,7 +1252,7 @@ static int heartbeat_root_cb (struct kvsroot *root, void *arg)
         && !root->is_primary
         && (now - root->last_update_time) > max_namespace_age
         && !zlist_size (root->wait_version_list)
-        && !zhash_size (root->transaction_requests)
+        && !zhashx_size (root->transaction_requests)
         && !kvstxn_mgr_ready_transaction_count (root->ktm)) {
         /* remove a root if it not the primary one, has timed out
          * on a follower node, and it does not have any watchers,
@@ -1602,9 +1602,9 @@ static void finalize_transaction_bynames (struct kvs_ctx *ctx,
             return;
         }
         nameval = json_string_value (name);
-        if ((msg = zhash_lookup (root->transaction_requests, nameval))) {
+        if ((msg = zhashx_lookup (root->transaction_requests, nameval))) {
             finalize_transaction_req (msg, &cbd);
-            zhash_delete (root->transaction_requests, nameval);
+            zhashx_delete (root->transaction_requests, nameval);
         }
     }
 }
@@ -2060,7 +2060,7 @@ static int stats_get_root_cb (struct kvsroot *root, void *arg)
                          "#no-op stores",
                          kvstxn_mgr_get_noop_stores (root->ktm),
                          "#transactions",
-                         zhash_size (root->transaction_requests),
+                         zhashx_size (root->transaction_requests),
                          "#readytransactions",
                          kvstxn_mgr_ready_transaction_count (root->ktm),
                          "store revision", root->seq))) {

src/modules/kvs/kvsroot.c

@@ -88,7 +88,7 @@ static void kvsroot_destroy (void *data)
         if (root->ktm)
             kvstxn_mgr_destroy (root->ktm);
         if (root->transaction_requests)
-            zhash_destroy (&(root->transaction_requests));
+            zhashx_destroy (&(root->transaction_requests));
         if (root->wait_version_list)
             zlist_destroy (&root->wait_version_list);
         if (root->setroot_queue)
@@ -98,6 +98,13 @@ static void kvsroot_destroy (void *data)
     }
 }
 
+/* zhashx_destructor_fn */
+static void flux_msg_decref_wrapper (void **item)
+{
+    flux_msg_t *msg = *item;
+    flux_msg_decref (msg);
+}
+
 struct kvsroot *kvsroot_mgr_create_root (kvsroot_mgr_t *krm,
                                          struct cache *cache,
                                          const char *hash_name,
@@ -136,11 +143,17 @@ struct kvsroot *kvsroot_mgr_create_root (kvsroot_mgr_t *krm,
         goto error;
     }
 
-    if (!(root->transaction_requests = zhash_new ())) {
-        flux_log_error (krm->h, "zhash_new");
+    if (!(root->transaction_requests = zhashx_new ())) {
+        flux_log_error (krm->h, "zhashx_new");
         goto error;
     }
 
+    zhashx_set_duplicator (root->transaction_requests,
+                           (zhashx_duplicator_fn *)flux_msg_incref);
+
+    zhashx_set_destructor (root->transaction_requests,
+                           (zhashx_destructor_fn *)flux_msg_decref_wrapper);
+
     if (!(root->wait_version_list = zlist_new ())) {
         flux_log_error (krm->h, "zlist_new");
         goto error;
@@ -261,17 +274,13 @@ int kvsroot_save_transaction_request (struct kvsroot *root,
         return -1;
     }
 
-    if (zhash_insert (root->transaction_requests,
-                      name,
-                      (void *)flux_msg_incref (request)) < 0) {
-        flux_msg_decref (request);
+    if (zhashx_insert (root->transaction_requests,
+                       name,
+                       (void *)request) < 0) {
         errno = EEXIST;
         return -1;
     }
 
-    zhash_freefn (root->transaction_requests,
-                  name,
-                  (zhash_free_fn *)flux_msg_decref);
     return 0;
 }
 

src/modules/kvs/kvsroot.h

@@ -30,7 +30,7 @@ struct kvsroot {
     int seq;
     char ref[BLOBREF_MAX_STRING_SIZE];
     kvstxn_mgr_t *ktm;
-    zhash_t *transaction_requests;
+    zhashx_t *transaction_requests;
     zlist_t *wait_version_list;
     double last_update_time;
     int flags;

src/modules/kvs/test/kvsroot.c

@@ -305,7 +305,7 @@ void basic_transaction_request_tests (void)
                                          0)) != NULL,
          "kvsroot_mgr_create_root works");
 
-    ok (zhash_size (root->transaction_requests) == 0,
+    ok (zhashx_size (root->transaction_requests) == 0,
         "before saving transaction, no transaction_requests in hash");
 
     if (!(request = flux_request_encode ("mytopic", "{ bar : 1 }")))
@@ -320,7 +320,7 @@ void basic_transaction_request_tests (void)
 
     flux_msg_destroy (request);
 
-    ok (zhash_size (root->transaction_requests) == 1,
+    ok (zhashx_size (root->transaction_requests) == 1,
         "after saving transaction, one transaction_requests in hash");
 
     kvsroot_mgr_destroy (krm);