ottobackwards commented on a change in pull request #257:
URL: https://github.com/apache/plc4x/pull/257#discussion_r664037340
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File path:
plc4j/integrations/apache-nifi/nifi-plc4x-processors/src/main/java/org/apache/plc4x/nifi/record/Plc4xReadResponseRecordSet.java
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@@ -0,0 +1,130 @@
+package org.apache.plc4x.nifi.record;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.apache.avro.Schema;
+import org.apache.nifi.avro.AvroTypeUtil;
+import org.apache.nifi.serialization.record.MapRecord;
+import org.apache.nifi.serialization.record.Record;
+import org.apache.nifi.serialization.record.RecordField;
+import org.apache.nifi.serialization.record.RecordSchema;
+import org.apache.nifi.serialization.record.RecordSet;
+import org.apache.plc4x.java.api.messages.PlcReadResponse;
+import org.apache.plc4x.java.api.value.PlcValue;
+import org.apache.plc4x.nifi.util.Plc4xCommon;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+public class Plc4xReadResponseRecordSet implements RecordSet, Closeable {
+ private static final Logger logger =
LoggerFactory.getLogger(Plc4xReadResponseRecordSet.class);
+ private final PlcReadResponse readResponse;
+ private final Set<String> rsColumnNames;
+ private boolean moreRows;
+
+ // TODO: review this AtomicReference?
+ // TODO: this could be enhanced checking if record schema should be
updated (via a cache boolean, checking property values is a nifi expression
language, etc)
Review comment:
So the logic would have to be (pseudo code):
```
// IF YOU ARE GOING TO JUST CACHE ONE
currentValue = property.evaluateexpressions.getvalue
if ( cachedSchema current key != currentValue) {
// this is not the same, the cached object doesn't match
// if we just cache the last schema we just dump the old on
// and build a new one, setting it as the cached schema now
cleanupCachedSchema()
buildCachedSchema()
cachedSchema current key = currentValue
}
// IF YOU ARE GOING TO CACHE MORE THAN ONE
// if this is going to change a lot, and maybe the user configures it we
*could* keep the
// schema in a map based on the key ( let's say the value switches between
20 things )
currentValue = property.evaluateexpressions.getvalue
if ( cached map does not contain current value ) {
cached map add current value buildCachedSchema()
}
return cached map get current value
```
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