pvalink: input proc if changed

documentation/qsrvpage.h

@@ -184,6 +184,7 @@ record(longin, "src") {
         time:false, # set record time during getValue
         monorder:0, # Order of record processing as a result of CP and CPP
         retry:false,# allow Put while disconnected.
+        always:false,# CP/CPP input link process even when .value field hasn't changed
         defer:false # Defer put
     }})
 }
@@ -283,6 +284,12 @@ Put to contain updates to multiple sub-fields.
 Allow a Put operation to be queued while the link is disconnected.
 The Put will be executed when the link becomes connected.
 
+@subsubsection qsrv_link_always always: CP/CPP always process
+
+By default (always:false) a subscription update will only cause a CP input link
+to scan if the structure field (cf. field: option) is marked as changed.
+Set to true to override this, and always process the link.
+
 @subsubsection qsrv_link_sem Link semantics/behavior
 
 This section attempts to answer some questions about how links behave in certain situations.

pdbApp/pvalink.h

@@ -78,7 +78,7 @@ struct pvaLinkConfig : public jlink
         MSI,
     } ms;
 
-    bool defer, pipeline, time, retry, local;
+    bool defer, pipeline, time, retry, local, always;
     int monorder;
 
     // internals used by jlif parsing
@@ -168,6 +168,7 @@ private:
 
     std::vector<dbCommon*> scan_records;
     std::vector<bool> scan_check_passive;
+    std::vector<epics::pvData::BitSet> scan_changed;
 
     DBManyLock atomic_lock;
 };
@@ -194,6 +195,7 @@ struct pvaLink : public pvaLinkConfig
     epics::pvData::PVStructure::const_shared_pointer fld_display,
                                                      fld_control,
                                                      fld_valueAlarm;
+    epics::pvData::BitSet proc_changed;
 
     // cached snapshot of alarm and  timestamp
     // captured in pvaGetValue().

pdbApp/pvalink_channel.cpp

@@ -256,6 +256,9 @@ void pvaLinkChannel::run_dbProcess(size_t idx)
     if(scan_check_passive[idx] && precord->scan!=0) {
         return;
 
+    } else if(connected_latched && !op_mon.changed.logical_and(scan_changed[idx])) {
+        return;
+
     } else if (precord->pact) {
         if (precord->tpro)
             printf("%s: Active %s\n",
@@ -327,6 +330,7 @@ void pvaLinkChannel::run()
 
             scan_records.clear();
             scan_check_passive.clear();
+            scan_changed.clear();
 
             for(links_t::iterator it(links.begin()), end(links.end()); it!=end; ++it)
             {
@@ -343,6 +347,7 @@ void pvaLinkChannel::run()
 
                 scan_records.push_back(link->plink->precord);
                 scan_check_passive.push_back(link->pp != pvaLink::CP);
+                scan_changed.push_back(link->proc_changed);
             }
 
             DBManyLock ML(scan_records);
@@ -351,8 +356,6 @@ void pvaLinkChannel::run()
 
             links_changed = false;
         }
-
-        // TODO: if connected_latched.  Option to test op_mon.changed with link::fld_value to only process on value change
     }
 
     if(scan_records.empty()) {

pdbApp/pvalink_jlif.cpp

@@ -17,6 +17,7 @@ pvaLinkConfig::pvaLinkConfig()
     ,time(false)
     ,retry(false)
     ,local(false)
+    ,always(false)
     ,monorder(0)
 {}
 pvaLinkConfig::~pvaLinkConfig() {}
@@ -41,6 +42,7 @@ using namespace pvalink;
  *  "monorder":#,// order of processing during CP scan
  *  "defer":true,// whether to immediately start Put, or only queue value to be sent
  *  "retry":true,// queue Put while disconnected, and retry on connect
+ *  "always":true,// CP/CPP updates always process a like, even if its input field hasn't changed
  *  "local":false,// Require local channel
  * }
  */
@@ -114,6 +116,8 @@ jlif_result pva_parse_bool(jlink *pjlink, int val)
             pvt->retry = !!val;
         } else if(pvt->jkey == "local") {
             pvt->local = !!val;
+        } else if(pvt->jkey == "always") {
+            pvt->always = !!val;
         } else if(pvt->debug) {
             printf("pva link parsing unknown integer depth=%u key=\"%s\" value=%s\n",
                    pvt->parseDepth, pvt->jkey.c_str(), val ? "true" : "false");

pdbApp/pvalink_link.cpp

@@ -114,6 +114,29 @@ void pvaLink::onTypeChange()
     fld_display = std::tr1::dynamic_pointer_cast<const pvd::PVStructure>(getSubField("display"));
     fld_control = std::tr1::dynamic_pointer_cast<const pvd::PVStructure>(getSubField("control"));
     fld_valueAlarm = std::tr1::dynamic_pointer_cast<const pvd::PVStructure>(getSubField("valueAlarm"));
+
+    proc_changed.clear();
+
+    // build mask of all "changed" bits associated with our .value
+    // CP/CPP input links will process this link only for updates where
+    // the changed mask and proc_changed share at least one set bit.
+    if(fld_value) {
+        // bit for this field
+        proc_changed.set(fld_value->getFieldOffset());
+
+        // bits of all parent fields
+        for(const pvd::PVStructure* parent = fld_value->getParent(); parent; parent = parent->getParent()) {
+            proc_changed.set(parent->getFieldOffset());
+        }
+
+        if(fld_value->getField()->getType()==pvd::structure)
+        {
+            // bits of all child fields
+            const pvd::PVStructure *val = static_cast<const pvd::PVStructure*>(fld_value.get());
+            for(size_t i=val->getFieldOffset(), N=val->getNextFieldOffset(); i<N; i++)
+                proc_changed.set(i);
+        }
+    }
 }
 
 } // namespace pvalink