[sdk] Move async stack trace fragment iteration from UI to sdk

This should have been implemented on the sdk/ layer in the first place.
We move it now so we can reuse it for the new StackTrace abstraction.

[email protected]

Bug: 433162438
Change-Id: I95b6d8b5fed0e571a9e820e29c730945209aa2cc
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6772976
Reviewed-by: Philip Pfaffe <[email protected]>
Commit-Queue: Simon Zünd <[email protected]>

Author: szuend

front_end/core/sdk/DebuggerModel.ts

@@ -972,6 +972,45 @@ export class DebuggerModel extends SDKModel<EventTypes> {
       ((arg0: CallFrame, arg1: EvaluationOptions) => Promise<EvaluationResult|null>)|null {
     return this.evaluateOnCallFrameCallback;
   }
+
+  /**
+   * Iterates the async stack trace parents.
+   *
+   * Retrieving cross-target async stack fragments requires CDP interaction, so this is an async generator.
+   *
+   * Important: This iterator will not yield the "synchronous" part of the stack trace, only the async parent chain.
+   */
+  async *
+      iterateAsyncParents(stackTraceOrPausedDetails: Protocol.Runtime.StackTrace|DebuggerPausedDetails):
+          AsyncGenerator<Protocol.Runtime.StackTrace> {
+    // We make `DebuggerPausedDetails` look like a stack trace. We are only interested in `parent` and `parentId` in any case.
+    let stackTrace: Protocol.Runtime.StackTrace = stackTraceOrPausedDetails instanceof DebuggerPausedDetails ?
+        {
+          callFrames: [],
+          parent: stackTraceOrPausedDetails.asyncStackTrace,
+          parentId: stackTraceOrPausedDetails.asyncStackTraceId
+        } :
+        stackTraceOrPausedDetails;
+
+    while (true) {
+      if (stackTrace.parent) {
+        stackTrace = stackTrace.parent;
+      } else if (stackTrace.parentId) {
+        const model: DebuggerModel|null = stackTrace.parentId.debuggerId ?
+            await DebuggerModel.modelForDebuggerId(stackTrace.parentId.debuggerId) :
+            this;
+        const maybeStackTrace = await model?.fetchAsyncStackTrace(stackTrace.parentId);
+        if (!maybeStackTrace) {
+          return;
+        }
+        stackTrace = maybeStackTrace;
+      } else {
+        return;
+      }
+
+      yield stackTrace;
+    }
+  }
 }
 
 const debuggerIdToModel = new Map<string, DebuggerModel>();

front_end/panels/sources/CallStackSidebarPane.ts

@@ -241,34 +241,20 @@ export class CallStackSidebarPane extends UI.View.SimpleView implements UI.Conte
       UI.Tooltip.Tooltip.install(this.callFrameWarningsElement, Array.from(uniqueWarnings).join('\n'));
     }
 
-    let debuggerModel = details.debuggerModel;
-    let asyncStackTraceId = details.asyncStackTraceId;
-    let asyncStackTrace: Protocol.Runtime.StackTrace|undefined|null = details.asyncStackTrace;
     let previousStackTrace: Protocol.Runtime.CallFrame[]|SDK.DebuggerModel.CallFrame[] = details.callFrames;
-    for (let {maxAsyncStackChainDepth} = this; maxAsyncStackChainDepth > 0; --maxAsyncStackChainDepth) {
-      if (!asyncStackTrace) {
-        if (!asyncStackTraceId) {
-          break;
-        }
-        if (asyncStackTraceId.debuggerId) {
-          const dm = await SDK.DebuggerModel.DebuggerModel.modelForDebuggerId(asyncStackTraceId.debuggerId);
-          if (!dm) {
-            break;
-          }
-          debuggerModel = dm;
-        }
-        asyncStackTrace = await debuggerModel.fetchAsyncStackTrace(asyncStackTraceId);
-        if (!asyncStackTrace) {
-          break;
-        }
-      }
+    let {maxAsyncStackChainDepth} = this;
+    let asyncStackTrace: Protocol.Runtime.StackTrace|null = null;
+    for await (asyncStackTrace of details.debuggerModel.iterateAsyncParents(details)) {
       const title = UI.UIUtils.asyncStackTraceLabel(asyncStackTrace.description, previousStackTrace);
       items.push(...await Item.createItemsForAsyncStack(
-          title, debuggerModel, asyncStackTrace.callFrames, this.locationPool, this.refreshItem.bind(this)));
+          title, details.debuggerModel, asyncStackTrace.callFrames, this.locationPool, this.refreshItem.bind(this)));
       previousStackTrace = asyncStackTrace.callFrames;
-      asyncStackTraceId = asyncStackTrace.parentId;
-      asyncStackTrace = asyncStackTrace.parent;
+
+      if (--maxAsyncStackChainDepth <= 0) {
+        break;
+      }
     }
+
     this.showMoreMessageElement.classList.toggle('hidden', !asyncStackTrace);
     this.items.replaceAll(items);
     for (const item of this.items) {