SharedPV monitor discard empty updates

src/pvrequest.cpp

@@ -71,5 +71,25 @@ BitMask request2mask(const FieldDesc* desc, const Value& pvRequest)
     return ret;
 }
 
+bool testmask(const Value& update, const BitMask& mask)
+{
+    auto desc = Value::Helper::desc(update);
+    auto store = Value::Helper::store_ptr(update);
+
+    if(!desc)
+        return false;
+
+    if(store->valid && mask[0])
+        return true;
+
+    if(desc->code==TypeCode::Struct) {
+        for(auto idx : range(size_t(1u), desc->size())) {
+            if(store[idx].valid && mask[idx])
+                return true;
+        }
+    }
+
+    return false;
+}
 
 }} // namespace pvxs::impl

src/pvrequest.h

@@ -16,6 +16,9 @@ namespace impl {
 PVXS_API
 BitMask request2mask(const FieldDesc* desc, const Value& pvRequest);
 
+PVXS_API
+bool testmask(const Value& update, const BitMask& mask);
+
 }} // namespace pvxs::impl
 
 #endif // PVREQUEST_H

src/servermon.cpp

@@ -220,28 +220,30 @@ struct ServerMonitorControl : public server::MonitorControlOp
         if(!mon)
             return false;
 
-        Guard G(mon->lock);
-
         if(val && mon->type && mon->type.get()!=Value::Helper::desc(val))
             throw std::logic_error("Type change not allowed in post().  Recommend pvxs::Value::cloneEmpty()");
 
-        if((mon->queue.size() < mon->limit) || force || !val) {
-            mon->queue.push_back(val);
+        if(testmask(val, mon->pvMask)) {
+            Guard G(mon->lock);
 
-        } else if(!maybe) {
-            // squash
-            assert(mon->limit>0 && !mon->queue.empty());
+            if((mon->queue.size() < mon->limit) || force || !val) {
+                mon->queue.push_back(val);
 
-            mon->queue.back().assign(val);
-            // TODO track overrun
+            } else if(!maybe) {
+                // squash
+                assert(mon->limit>0 && !mon->queue.empty());
 
-        } else {
-            // nope
+                mon->queue.back().assign(val);
+                // TODO track overrun
+
+            } else {
+                // nope
+            }
+
+            if(auto serv = server.lock())
+                MonitorOp::maybeReply(serv.get(), mon);
         }
 
-        if(auto serv = server.lock())
-            MonitorOp::maybeReply(serv.get(), mon);
-
         return mon->queue.size() < mon->limit;
     }
 

test/testpvreq.cpp

@@ -71,6 +71,36 @@ void testPvRequest()
     }
 }
 
+void testPvMask()
+{
+    auto val = nt::NTScalar{TypeCode::String}.create();
+
+    auto rdef = TypeDef(TypeCode::Struct, {
+                            members::Struct("field", {
+                                members::Struct("value", {}),
+                            })
+                        });
+
+    auto mask = request2mask(Value::Helper::desc(val), rdef.create());
+
+    testFalse(testmask(val, mask));
+
+    val["alarm.status"].mark();
+    testFalse(testmask(val, mask));
+
+    val["value"].mark();
+    testTrue(testmask(val, mask));
+
+    val["alarm.status"].unmark();
+    testTrue(testmask(val, mask));
+
+    val.unmark();
+    testFalse(testmask(val, mask));
+
+    val.mark();
+    testTrue(testmask(val, mask));
+}
+
 struct TestBuilder : client::detail::CommonBuilder<TestBuilder, client::detail::PRBase>
 {
     TestBuilder()
@@ -349,10 +379,11 @@ void testArgs()
 
 MAIN(testpvreq)
 {
-    testPlan(30);
+    testPlan(36);
     testSetup();
     logger_config_env();
     testPvRequest();
+    testPvMask();
     testEmpty();
     testAssemble();
     testParseEmpty();