1 files changed, 81 insertions, 0 deletions
diff --git a/devtools/shared/commands/resource/legacy-listeners/thread-states.js b/devtools/shared/commands/resource/legacy-listeners/thread-states.js
new file mode 100644
index 0000000000..42c922072a
--- /dev/null
+++ b/devtools/shared/commands/resource/legacy-listeners/thread-states.js
@@ -0,0 +1,81 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const ResourceCommand = require("resource://devtools/shared/commands/resource/resource-command.js");
+
+module.exports = async function ({ targetCommand, targetFront, onAvailable }) {
+  const isBrowserToolbox =
+    targetCommand.descriptorFront.isBrowserProcessDescriptor;
+  const isNonTopLevelFrameTarget =
+    !targetFront.isTopLevel &&
+    targetFront.targetType === targetCommand.TYPES.FRAME;
+
+  if (isBrowserToolbox && isNonTopLevelFrameTarget) {
+    // In the BrowserToolbox, non-top-level frame targets are already
+    // debugged via content-process targets.
+    return;
+  }
+
+  // Wait for the thread actor to be attached, otherwise getFront(thread) will throw for worker targets
+  // This is because worker target are still kind of descriptors and are only resolved into real target
+  // after being attached. And the thread actor ID is only retrieved and available after being attached.
+  await targetFront.onThreadAttached;
+
+  if (targetFront.isDestroyed()) {
+    return;
+  }
+  const threadFront = await targetFront.getFront("thread");
+
+  let isInterrupted = false;
+  const onPausedPacket = packet => {
+    // If paused by an explicit interrupt, which are generated by the
+    // slow script dialog and internal events such as setting
+    // breakpoints, ignore the event.
+    const { why } = packet;
+    if (why.type === "interrupted" && !why.onNext) {
+      isInterrupted = true;
+      return;
+    }
+
+    // Ignore attached events because they are not useful to the user.
+    if (why.type == "alreadyPaused" || why.type == "attached") {
+      return;
+    }
+
+    onAvailable([
+      {
+        resourceType: ResourceCommand.TYPES.THREAD_STATE,
+        state: "paused",
+        why,
+        frame: packet.frame,
+      },
+    ]);
+  };
+  threadFront.on("paused", onPausedPacket);
+
+  threadFront.on("resumed", packet => {
+    // NOTE: the client suppresses resumed events while interrupted
+    // to prevent unintentional behavior.
+    // see [client docs](devtools/client/debugger/src/client/README.md#interrupted) for more information.
+    if (isInterrupted) {
+      isInterrupted = false;
+      return;
+    }
+
+    onAvailable([
+      {
+        resourceType: ResourceCommand.TYPES.THREAD_STATE,
+        state: "resumed",
+      },
+    ]);
+  });
+
+  // Notify about already paused thread
+  const pausedPacket = threadFront.getLastPausePacket();
+  if (pausedPacket) {
+    onPausedPacket(pausedPacket);
+  }
+};