refactor: simplify tracing code — remove dead code, extract helpers

- Remove unused createClientSpan() method (52 lines) and its 2 tests.
  Replaced by emitRetroactiveClientSpan() which creates spans with
  proper scheduling-to-completion duration.

- Extract emitClientSpanIfTracked() helper to eliminate 4× duplicated
  retroactive client span emission blocks in task/sub-orchestration
  completed/failed handlers.

- Extract storeSchedulingMetadata() helper to consolidate 2× duplicated
  scheduling metadata storage in handleTaskScheduled and
  handleSubOrchestrationCreated.

Net: -151 lines.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: torosent

client/src/main/java/com/microsoft/durabletask/TaskOrchestrationExecutor.java

@@ -545,18 +545,7 @@ private void handleTaskScheduled(HistoryEvent e) {
 
             TaskScheduledEvent taskScheduled = e.getTaskScheduled();
 
-            // Store scheduling metadata for retroactive client span at completion time.
-            // Use orchestrationSpanContext as parent so the client span is a child of the orchestration span.
-            Instant scheduledTime = e.hasTimestamp()
-                    ? DataConverter.getInstantFromTimestamp(e.getTimestamp())
-                    : null;
-            TraceContext spanParent = this.orchestrationSpanContext != null
-                    ? this.orchestrationSpanContext : this.parentTraceContext;
-            this.scheduledTaskInfoMap.put(taskId, new ScheduledTaskInfo(
-                    taskScheduled.getName(),
-                    scheduledTime,
-                    spanParent,
-                    TracingHelper.TYPE_ACTIVITY));
+            storeSchedulingMetadata(taskId, taskScheduled.getName(), TracingHelper.TYPE_ACTIVITY, e);
 
             // The history shows that this orchestrator created a durable task in a previous execution.
             // We can therefore remove it from the map of pending actions. If we can't find the pending
@@ -595,17 +584,7 @@ private void handleTaskCompleted(HistoryEvent e) {
 
                 // Emit a retroactive Client span covering scheduling-to-completion duration.
                 // Matches .NET SDK's EmitTraceActivityForTaskCompleted pattern.
-                ScheduledTaskInfo info = this.scheduledTaskInfoMap.remove(taskId);
-                if (info != null) {
-                    TracingHelper.emitRetroactiveClientSpan(
-                            info.spanType + ":" + info.taskName,
-                            info.parentTraceContext,
-                            info.spanType,
-                            info.taskName,
-                            this.instanceId,
-                            taskId,
-                            info.scheduledTime);
-                }
+                emitClientSpanIfTracked(taskId);
             }
             CompletableTask task = record.getTask();
             try {
@@ -631,17 +610,7 @@ private void handleTaskFailed(HistoryEvent e) {
                 // TODO: Log task failure, including the number of bytes in the result
 
                 // Emit a retroactive Client span covering scheduling-to-failure duration.
-                ScheduledTaskInfo info = this.scheduledTaskInfoMap.remove(taskId);
-                if (info != null) {
-                    TracingHelper.emitRetroactiveClientSpan(
-                            info.spanType + ":" + info.taskName,
-                            info.parentTraceContext,
-                            info.spanType,
-                            info.taskName,
-                            this.instanceId,
-                            taskId,
-                            info.scheduledTime);
-                }
+                emitClientSpanIfTracked(taskId);
             }
 
             CompletableTask<?> task = record.getTask();
@@ -798,17 +767,8 @@ private void handleSubOrchestrationCreated(HistoryEvent e) {
             int taskId = e.getEventId();
             SubOrchestrationInstanceCreatedEvent subOrchestrationInstanceCreated = e.getSubOrchestrationInstanceCreated();
 
-            // Store scheduling metadata for retroactive client span at completion time
-            Instant scheduledTime = e.hasTimestamp()
-                    ? DataConverter.getInstantFromTimestamp(e.getTimestamp())
-                    : null;
-            TraceContext spanParent = this.orchestrationSpanContext != null
-                    ? this.orchestrationSpanContext : this.parentTraceContext;
-            this.scheduledTaskInfoMap.put(taskId, new ScheduledTaskInfo(
-                    subOrchestrationInstanceCreated.getName(),
-                    scheduledTime,
-                    spanParent,
-                    TracingHelper.TYPE_ORCHESTRATION));
+            storeSchedulingMetadata(taskId, subOrchestrationInstanceCreated.getName(),
+                    TracingHelper.TYPE_ORCHESTRATION, e);
 
             OrchestratorAction taskAction = this.pendingActions.remove(taskId);
             if (taskAction == null) {
@@ -841,17 +801,7 @@ private void handleSubOrchestrationCompleted(HistoryEvent e) {
                         rawResult != null ? rawResult : "(null)"));
 
                 // Emit a retroactive Client span covering scheduling-to-completion duration.
-                ScheduledTaskInfo info = this.scheduledTaskInfoMap.remove(taskId);
-                if (info != null) {
-                    TracingHelper.emitRetroactiveClientSpan(
-                            info.spanType + ":" + info.taskName,
-                            info.parentTraceContext,
-                            info.spanType,
-                            info.taskName,
-                            this.instanceId,
-                            taskId,
-                            info.scheduledTime);
-                }
+                emitClientSpanIfTracked(taskId);
             }
             CompletableTask task = record.getTask();
             try {
@@ -877,17 +827,7 @@ private void handleSubOrchestrationFailed(HistoryEvent e){
                 // TODO: Log task failure, including the number of bytes in the result
 
                 // Emit a retroactive Client span covering scheduling-to-failure duration.
-                ScheduledTaskInfo info = this.scheduledTaskInfoMap.remove(taskId);
-                if (info != null) {
-                    TracingHelper.emitRetroactiveClientSpan(
-                            info.spanType + ":" + info.taskName,
-                            info.parentTraceContext,
-                            info.spanType,
-                            info.taskName,
-                            this.instanceId,
-                            taskId,
-                            info.scheduledTime);
-                }
+                emitClientSpanIfTracked(taskId);
             }
 
             CompletableTask<?> task = record.getTask();
@@ -1104,6 +1044,35 @@ public Class<V> getDataType() {
             }
         }
 
+        /**
+         * Emits a retroactive Client span for a completed/failed task, if scheduling metadata was tracked.
+         */
+        private void emitClientSpanIfTracked(int taskId) {
+            ScheduledTaskInfo info = this.scheduledTaskInfoMap.remove(taskId);
+            if (info != null) {
+                TracingHelper.emitRetroactiveClientSpan(
+                        info.spanType + ":" + info.taskName,
+                        info.parentTraceContext,
+                        info.spanType,
+                        info.taskName,
+                        this.instanceId,
+                        taskId,
+                        info.scheduledTime);
+            }
+        }
+
+        /**
+         * Stores scheduling metadata for a task so a retroactive client span can be emitted at completion time.
+         */
+        private void storeSchedulingMetadata(int taskId, String taskName, String spanType, HistoryEvent e) {
+            Instant scheduledTime = e.hasTimestamp()
+                    ? DataConverter.getInstantFromTimestamp(e.getTimestamp()) : null;
+            TraceContext spanParent = this.orchestrationSpanContext != null
+                    ? this.orchestrationSpanContext : this.parentTraceContext;
+            this.scheduledTaskInfoMap.put(taskId, new ScheduledTaskInfo(
+                    taskName, scheduledTime, spanParent, spanType));
+        }
+
         /**
          * Stores scheduling metadata for retroactive client span creation at completion time.
          * Matches .NET SDK pattern where client spans are emitted with the full scheduling-to-completion duration.

client/src/main/java/com/microsoft/durabletask/TracingHelper.java

@@ -219,74 +219,6 @@ static Span startSpanWithStartTime(
         return span;
     }
 
-    /**
-     * Creates a short-lived Client-kind span for scheduling an activity or sub-orchestration,
-     * captures its trace context as a protobuf {@code TraceContext}, and ends the span immediately.
-     * This mirrors the .NET SDK pattern of paired Client+Server spans.
-     *
-     * @param spanName       The span name (e.g. "activity:GetWeather").
-     * @param parentContext  The parent trace context from the orchestration, may be {@code null}.
-     * @param type           The durabletask.type value (e.g. "activity").
-     * @param taskName       The task name attribute value.
-     * @param instanceId     The orchestration instance ID.
-     * @param taskId         The task sequence ID.
-     * @return A {@code TraceContext} captured from the Client span, or the original parentContext if tracing is unavailable.
-     */
-    @Nullable
-    static TraceContext createClientSpan(
-            String spanName,
-            @Nullable TraceContext parentContext,
-            String type,
-            String taskName,
-            @Nullable String instanceId,
-            int taskId) {
-
-        Tracer tracer = GlobalOpenTelemetry.getTracer(TRACER_NAME);
-        SpanBuilder spanBuilder = tracer.spanBuilder(spanName)
-                .setSpanKind(SpanKind.CLIENT)
-                .setAttribute(ATTR_TYPE, type)
-                .setAttribute(ATTR_TASK_NAME, taskName)
-                .setAttribute(ATTR_TASK_ID, String.valueOf(taskId));
-
-        if (instanceId != null) {
-            spanBuilder.setAttribute(ATTR_INSTANCE_ID, instanceId);
-        }
-
-        Context parentCtx = extractTraceContext(parentContext);
-        if (parentCtx != null) {
-            spanBuilder.setParent(parentCtx);
-        }
-
-        Span clientSpan = spanBuilder.startSpan();
-
-        // Capture the client span's context before ending it
-        TraceContext captured;
-        try {
-            SpanContext sc = clientSpan.getSpanContext();
-            if (sc.isValid()) {
-                String traceParent = String.format("00-%s-%s-%02x",
-                        sc.getTraceId(), sc.getSpanId(), sc.getTraceFlags().asByte());
-
-                String traceState = sc.getTraceState().asMap()
-                        .entrySet()
-                        .stream()
-                        .map(entry -> entry.getKey() + "=" + entry.getValue())
-                        .collect(Collectors.joining(","));
-
-                TraceContext.Builder builder = TraceContext.newBuilder().setTraceParent(traceParent);
-                if (traceState != null && !traceState.isEmpty()) {
-                    builder.setTraceState(StringValue.of(traceState));
-                }
-                captured = builder.build();
-            } else {
-                captured = parentContext;
-            }
-        } finally {
-            clientSpan.end();
-        }
-        return captured;
-    }
-
     /**
      * Ends the given span, optionally recording an error.
      *

client/src/test/java/com/microsoft/durabletask/TracingHelperTest.java

@@ -239,58 +239,6 @@ void getCurrentTraceContext_roundTrip() {
                 extractedSpan.getSpanContext().getSpanId());
     }
 
-    @Test
-    void createClientSpan_createsClientKindSpan_withNewSpanId() {
-        // Create a parent context
-        Tracer tracer = openTelemetry.getTracer("test");
-        Span parentSpan = tracer.spanBuilder("parent-orch").startSpan();
-        TraceContext parentCtx;
-        try (Scope ignored = parentSpan.makeCurrent()) {
-            parentCtx = TracingHelper.getCurrentTraceContext();
-        } finally {
-            parentSpan.end();
-        }
-        assertNotNull(parentCtx);
-        spanExporter.reset();
-
-        // Create a client span
-        TraceContext clientCtx = TracingHelper.createClientSpan(
-                "activity:GetWeather", parentCtx,
-                TracingHelper.TYPE_ACTIVITY, "GetWeather", "instance-123", 3);
-
-        assertNotNull(clientCtx);
-        assertNotNull(clientCtx.getTraceParent());
-
-        // Client span should have the same trace ID but different span ID
-        String parentTraceId = parentCtx.getTraceParent().split("-")[1];
-        String clientTraceId = clientCtx.getTraceParent().split("-")[1];
-        String parentSpanId = parentCtx.getTraceParent().split("-")[2];
-        String clientSpanId = clientCtx.getTraceParent().split("-")[2];
-        assertEquals(parentTraceId, clientTraceId, "Should share the same trace ID");
-        assertNotEquals(parentSpanId, clientSpanId, "Should have a new span ID");
-
-        // Verify the exported client span has correct attributes and kind
-        List<SpanData> spans = spanExporter.getFinishedSpanItems();
-        assertEquals(1, spans.size());
-        SpanData sd = spans.get(0);
-        assertEquals("activity:GetWeather", sd.getName());
-        assertEquals(SpanKind.CLIENT, sd.getKind());
-        assertEquals("activity", sd.getAttributes().get(io.opentelemetry.api.common.AttributeKey.stringKey("durabletask.type")));
-        assertEquals("GetWeather", sd.getAttributes().get(io.opentelemetry.api.common.AttributeKey.stringKey("durabletask.task.name")));
-        assertEquals("instance-123", sd.getAttributes().get(io.opentelemetry.api.common.AttributeKey.stringKey("durabletask.task.instance_id")));
-        assertEquals("3", sd.getAttributes().get(io.opentelemetry.api.common.AttributeKey.stringKey("durabletask.task.task_id")));
-    }
-
-    @Test
-    void createClientSpan_withNullParent_returnsNull() {
-        TraceContext result = TracingHelper.createClientSpan(
-                "activity:Test", null, TracingHelper.TYPE_ACTIVITY, "Test", null, 0);
-        // When parent is null, the span has no parent but still creates a valid context
-        // (or returns null if the tracer returns an invalid span)
-        // With a registered SDK, it should create a root span
-        assertNotNull(result);
-    }
-
     @Test
     void emitTimerSpan_createsInternalSpanWithFireAt() {
         TracingHelper.emitTimerSpan("MyOrchestration", "instance-1", 5, "2026-01-01T00:00:00Z", null, null);