Improve documentation of workflow outputs

modules/nextflow/src/main/groovy/nextflow/extension/PublishOp.groovy

@@ -52,7 +52,7 @@ class PublishOp {
 
     private IndexOpts indexOpts
 
-    private List indexRecords = []
+    private List publishedValues = []
 
     private DataflowVariable target
 
@@ -106,7 +106,7 @@ class PublishOp {
      * @param value
      */
     protected void onNext(value) {
-        log.trace "Publish operator received: $value"
+        log.trace "Received value for workflow output '${name}': ${value}"
 
         // evaluate dynamic path
         final targetResolver = getTargetDir(value)
@@ -130,10 +130,11 @@ class PublishOp {
             publisher.apply(files, sourceDir)
         }
 
-        // append record to index
-        final normalized = normalizePaths(value, targetResolver)
-        log.trace "Normalized record for index file: ${normalized}"
-        indexRecords << normalized
+        // publish value to workflow output
+        final normalizedValue = normalizeValue(value, targetResolver)
+
+        log.trace "Published value to workflow output '${name}': ${normalizedValue}"
+        publishedValues << normalizedValue
     }
 
     /**
@@ -216,37 +217,37 @@ class PublishOp {
      */
     protected void onComplete() {
         // publish individual record if source is a value channel
-        final value = CH.isValue(source)
-            ? indexRecords.first()
-            : indexRecords
+        final outputValue = CH.isValue(source)
+            ? publishedValues.first()
+            : publishedValues
 
         // publish workflow output
         final indexPath = indexOpts
             ? session.outputDir.resolve(indexOpts.path)
             : null
-        session.notifyWorkflowOutput(new WorkflowOutputEvent(name, value, indexPath))
+        session.notifyWorkflowOutput(new WorkflowOutputEvent(name, outputValue, indexPath))
 
         // write value to index file
         if( indexOpts ) {
             final ext = indexPath.getExtension()
             indexPath.parent.mkdirs()
             if( ext == 'csv' ) {
-                new CsvWriter(header: indexOpts.header, sep: indexOpts.sep).apply(indexRecords, indexPath)
+                new CsvWriter(header: indexOpts.header, sep: indexOpts.sep).apply(publishedValues, indexPath)
             }
             else if( ext == 'json' ) {
-                indexPath.text = DumpHelper.prettyPrintJson(value)
+                indexPath.text = DumpHelper.prettyPrintJson(outputValue)
             }
             else if( ext == 'yaml' || ext == 'yml' ) {
-                indexPath.text = DumpHelper.prettyPrintYaml(value)
+                indexPath.text = DumpHelper.prettyPrintYaml(outputValue)
             }
             else {
                 throw new ScriptRuntimeException("Invalid extension '${ext}' for index file '${indexOpts.path}' -- should be CSV, JSON, or YAML")
             }
             session.notifyFilePublish(new FilePublishEvent(null, indexPath, publishOpts.labels as List))
         }
 
-        log.trace "Publish operator complete"
-        target.bind(indexPath ?: value)
+        log.trace "Completed workflow output '${name}'"
+        target.bind(indexPath ?: outputValue)
     }
 
     /**
@@ -283,7 +284,7 @@ class PublishOp {
      * @param value
      * @param targetResolver
      */
-    protected Object normalizePaths(value, targetResolver) {
+    protected Object normalizeValue(value, targetResolver) {
         if( value instanceof Path ) {
             return normalizePath(value, targetResolver)
         }
@@ -293,9 +294,9 @@ class PublishOp {
                 if( el instanceof Path )
                     return normalizePath(el, targetResolver)
                 if( el instanceof Collection<Path> )
-                    return normalizePaths(el, targetResolver)
+                    return normalizeValue(el, targetResolver)
                 if( el instanceof Map )
-                    return normalizePaths(el, targetResolver)
+                    return normalizeValue(el, targetResolver)
                 return el
             }
         }
@@ -305,9 +306,9 @@ class PublishOp {
                 if( v instanceof Path )
                     return [k, normalizePath(v, targetResolver)]
                 if( v instanceof Collection<Path> )
-                    return [k, normalizePaths(v, targetResolver)]
+                    return [k, normalizeValue(v, targetResolver)]
                 if( v instanceof Map )
-                    return [k, normalizePaths(v, targetResolver)]
+                    return [k, normalizeValue(v, targetResolver)]
                 return [k, v]
             }
         }

modules/nextflow/src/main/groovy/nextflow/trace/TraceObserverV2.groovy

@@ -121,15 +121,19 @@ interface TraceObserverV2 {
     default void onFlowError(TaskEvent event) {}
 
     /**
-     * Invoked when a workflow output is published.
+     * Invoked when a workflow output is completed.
+     *
+     * For a given workflow output, this event is guaranteed
+     * to be emitted after all files for that output have been
+     * published via onFilePublish().
      *
      * @param event
      */
     default void onWorkflowOutput(WorkflowOutputEvent event) {}
 
     /**
-     * Invoked when a file is published, either by a `publishDir` directive
-     * or a workflow output.
+     * Invoked when a file is published by a workflow output
+     * or `publishDir` directive.
      *
      * @param event
      */

modules/nextflow/src/main/groovy/nextflow/trace/event/FilePublishEvent.groovy

@@ -22,7 +22,8 @@ import groovy.transform.Canonical
 import groovy.transform.CompileStatic
 
 /**
- * Models a file publish event.
+ * Models a file publish event, which is emitted for each file
+ * that is published in a workflow output or publishDir.
  *
  * @author Ben Sherman <bentshermann@gmail.com>
  */

modules/nextflow/src/main/groovy/nextflow/trace/event/WorkflowOutputEvent.groovy

@@ -22,7 +22,8 @@ import groovy.transform.Canonical
 import groovy.transform.CompileStatic
 
 /**
- * Models a workflow output event.
+ * Models a workflow output event, which is emitted for each
+ * workflow output when it is completed.
  *
  * @author Ben Sherman <bentshermann@gmail.com>
  */
@@ -34,7 +35,13 @@ class WorkflowOutputEvent {
      */
     String name
     /**
-     * The value of the workflow output. It will be null if the index file was specified.
+     * The value of the workflow output.
+     *
+     * If the source is a dataflow channel. this value is an unordered
+     * collection of the published values from the channel. If the source
+     * is a dataflow value, this value is the published value.
+     *
+     * If the index file was enabled, this value is null.
      */
     Object value
     /**