Bug 1619622 - Stop fetching the sources twice. r=jdescottes,jlast

We already do that from actions, once per added thread.
Only the timing may be different.

Differential Revision: https://phabricator.services.mozilla.com/D72686

devtools/client/debugger/src/actions/threads.js

@@ -18,23 +18,25 @@ import {
   getSourceActorsForThread,
 } from "../selectors";
 
-function addThreads(
+async function addThreads(
   { dispatch, client, getState }: ThunkArgs,
   addedThreads: ThreadList
 ) {
   const cx = getContext(getState());
   dispatch(({ type: "INSERT_THREADS", cx, threads: addedThreads }: Action));
 
   // Fetch the sources and install breakpoints on any new workers.
-  // NOTE: This runs in the background and fails quietly because it is
-  // pretty easy for sources to throw during the fetch if their thread
-  // shuts down, which would cause test failures.
-  for (const thread of addedThreads) {
-    client
-      .fetchThreadSources(thread.actor)
-      .then(sources => dispatch(newGeneratedSources(sources)))
-      .catch(e => console.error(e));
-  }
+  await Promise.all(addedThreads.map(async thread => {
+    try {
+      const sources = await client.fetchThreadSources(thread.actor);
+      await dispatch(newGeneratedSources(sources));
+    } catch (e) {
+      // NOTE: This fails quietly because it is pretty easy for sources to
+      // throw during the fetch if their thread shuts down,
+      // which would cause test failures.
+      console.error(e);
+    }
+  }));
 }
 
 function removeThreads(

devtools/client/debugger/src/client/firefox.js

@@ -86,17 +86,6 @@ async function onTargetAvailable({
     targetFront.isWebExtension
   );
 
-  // Fetch the sources for all the targets
-  //
-  // In Firefox, we need to initially request all of the sources. This
-  // usually fires off individual `newSource` notifications as the
-  // debugger finds them, but there may be existing sources already in
-  // the debugger (if it's paused already, or if loading the page from
-  // bfcache) so explicity fire `newSource` events for all returned
-  // sources.
-  const sources = await clientCommands.fetchSources();
-  await actions.newGeneratedSources(sources);
-
   await actions.addTarget(targetFront);
 
   await clientCommands.checkIfAlreadyPaused();