DPL: make adding distsubtimeframe & co stable

Previous version could have failed in case of multiple source devices as
in the case of multiple readers.

This PR aims at making sure the device picked to attach the
DISTSUBTIMEFRAME is always the same.

Author: ktf

Framework/Core/src/WorkflowHelpers.cxx

@@ -541,18 +541,33 @@ void WorkflowHelpers::injectServiceDevices(WorkflowSpec& workflow, ConfigContext
     } else if (providesDISTSTF) {
       ccdbBackend.inputs.push_back(InputSpec{"tfn", dstf, Lifetime::Timeframe});
     } else {
-      for (auto& dp : workflow) {
-        bool enumOnly = dp.inputs.size() == 1 && dp.inputs[0].lifetime == Lifetime::Enumeration;
-        bool timerOnly = dp.inputs.size() == 1 && dp.inputs[0].lifetime == Lifetime::Timer;
-        if (enumOnly == true) {
-          dp.outputs.push_back(OutputSpec{{"ccdb-diststf"}, dstf, Lifetime::Timeframe});
-          ccdbBackend.inputs.push_back(InputSpec{"tfn", dstf, Lifetime::Timeframe});
-          break;
-        } else if (timerOnly == true) {
-          dstf = DataSpecUtils::asConcreteDataMatcher(dp.outputs[0]);
-          ccdbBackend.inputs.push_back(InputSpec{{"tfn"}, dstf, Lifetime::Timeframe});
-          break;
+      // We find the first device which has either just enumerations or
+      // just timers, and we add the DISTSUBTIMEFRAME to it.
+      // Notice how we do so in a stable manner by sorting the devices
+      // by name.
+      int enumCandidate = -1;
+      int timerCandidate = -1;
+      for (size_t wi = 0; wi < workflow.size(); wi++) {
+        auto& dp = workflow[wi];
+        if (dp.inputs.size() != 1) {
+          continue;
         }
+        auto lifetime = dp.inputs[0].lifetime;
+        if (lifetime == Lifetime::Enumeration && (enumCandidate == -1 || workflow[enumCandidate].name > dp.name)) {
+          enumCandidate = wi;
+        }
+        if (lifetime == Lifetime::Timer && (timerCandidate == -1 || workflow[timerCandidate].name > dp.name)) {
+          timerCandidate = wi;
+        }
+      }
+      if (enumCandidate != -1) {
+        auto& dp = workflow[enumCandidate];
+        dp.outputs.push_back(OutputSpec{{"ccdb-diststf"}, dstf, Lifetime::Timeframe});
+        ccdbBackend.inputs.push_back(InputSpec{"tfn", dstf, Lifetime::Timeframe});
+      } else if (timerCandidate != -1) {
+        auto& dp = workflow[timerCandidate];
+        dstf = DataSpecUtils::asConcreteDataMatcher(dp.outputs[0]);
+        ccdbBackend.inputs.push_back(InputSpec{{"tfn"}, dstf, Lifetime::Timeframe});
       }
     }
 
@@ -573,18 +588,33 @@ void WorkflowHelpers::injectServiceDevices(WorkflowSpec& workflow, ConfigContext
       }
     }
     if (requiresDISTSUBTIMEFRAME) {
-      for (auto& dp : workflow) {
-        bool enumOnly = dp.inputs.size() == 1 && dp.inputs[0].lifetime == Lifetime::Enumeration;
-        bool timerOnly = dp.inputs.size() == 1 && dp.inputs[0].lifetime == Lifetime::Timer;
-        if (enumOnly == true) {
-          dp.outputs.push_back(OutputSpec{{"ccdb-diststf"}, dstf, Lifetime::Timeframe});
-          ccdbBackend.inputs.push_back(InputSpec{"tfn", dstf, Lifetime::Timeframe});
-          break;
-        } else if (timerOnly == true) {
-          dstf = DataSpecUtils::asConcreteDataMatcher(dp.outputs[0]);
-          ccdbBackend.inputs.push_back(InputSpec{{"tfn"}, dstf, Lifetime::Timeframe});
-          break;
+      // We find the first device which has either just enumerations or
+      // just timers, and we add the DISTSUBTIMEFRAME to it.
+      // Notice how we do so in a stable manner by sorting the devices
+      // by name.
+      int enumCandidate = -1;
+      int timerCandidate = -1;
+      for (size_t wi = 0; wi < workflow.size(); wi++) {
+        auto& dp = workflow[wi];
+        if (dp.inputs.size() != 1) {
+          continue;
         }
+        auto lifetime = dp.inputs[0].lifetime;
+        if (lifetime == Lifetime::Enumeration && (enumCandidate == -1 || workflow[enumCandidate].name > dp.name)) {
+          enumCandidate = wi;
+        }
+        if (lifetime == Lifetime::Timer && (timerCandidate == -1 || workflow[timerCandidate].name > dp.name)) {
+          timerCandidate = wi;
+        }
+      }
+      if (enumCandidate != -1) {
+        auto& dp = workflow[enumCandidate];
+        dp.outputs.push_back(OutputSpec{{"ccdb-diststf"}, dstf, Lifetime::Timeframe});
+        ccdbBackend.inputs.push_back(InputSpec{"tfn", dstf, Lifetime::Timeframe});
+      } else if (timerCandidate != -1) {
+        auto& dp = workflow[timerCandidate];
+        dstf = DataSpecUtils::asConcreteDataMatcher(dp.outputs[0]);
+        ccdbBackend.inputs.push_back(InputSpec{{"tfn"}, dstf, Lifetime::Timeframe});
       }
     }
   }