send DBE_PROPERTY events only if property field actually changed

dirk-zimoch · Aug 30, 2024 · 5385213 · 5385213
1 parent 052a0c7
commit 5385213
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diff --git a/documentation/RELEASE_NOTES.md b/documentation/RELEASE_NOTES.md
@@ -22,6 +22,11 @@ should also be read to understand what has changed since earlier releases:
 
 ## Changes made on the 7.0 branch since 7.0.8.1
 
+### DBE_PROPERTY event rate changed
+
+Updating property fields now only post DBE_PROPERTY events if the
+field actually changed.
+
 ### Allow users to delete previously created records from the database
 
 From this release, record instances and aliases that have already been loaded

diff --git a/modules/database/src/ioc/db/dbAccess.c b/modules/database/src/ioc/db/dbAccess.c
@@ -1325,6 +1325,7 @@ long dbPut(DBADDR *paddr, short dbrType,
     long status = 0;
     dbFldDes *pfldDes;
     int isValueField;
+    int propertyUpdate = paddr->pfldDes->prop && precord->mlis.count;
 
     if (special == SPC_ATTRIBUTE)
         return S_db_noMod;
@@ -1369,8 +1370,22 @@ long dbPut(DBADDR *paddr, short dbrType,
         if (nRequest < 1) {
             recGblSetSevr(precord, LINK_ALARM, INVALID_ALARM);
         } else {
-            status = dbFastPutConvertRoutine[dbrType][field_type](pbuffer,
-                paddr->pfield, paddr);
+            if (propertyUpdate && paddr->field_size <= sizeof(epicsAny)) {
+                epicsAny propBuffer;
+                status = dbFastPutConvertRoutine[dbrType][field_type](pbuffer,
+                    &propBuffer, paddr);
+                if (!status) {
+                    if (memcmp(paddr->pfield, &propBuffer, paddr->field_size) != 0) {
+                        memcpy(paddr->pfield, &propBuffer, paddr->field_size);
+                    } else {
+                        /* suppress DBE_PROPERTY event if property did not change */
+                        propertyUpdate = 0;
+                    }
+                }
+            } else {
+                status = dbFastPutConvertRoutine[dbrType][field_type](pbuffer,
+                    paddr->pfield, paddr);
+            }
             nRequest = 1;
         }
     }
@@ -1391,11 +1406,7 @@ long dbPut(DBADDR *paddr, short dbrType,
     if (precord->mlis.count &&
         !(isValueField && pfldDes->process_passive))
         db_post_events(precord, pfieldsave, DBE_VALUE | DBE_LOG);
-    /* If this field is a property (metadata) field,
-     * then post a property change event (even if the field
-     * didn't change).
-     */
-    if (precord->mlis.count && pfldDes->prop)
+    if (propertyUpdate)
         db_post_events(precord, NULL, DBE_PROPERTY);
 done:
     paddr->pfield = pfieldsave;