1 files changed, 362 insertions, 0 deletions
diff --git a/devtools/server/connectors/js-process-actor/DevToolsProcessChild.sys.mjs b/devtools/server/connectors/js-process-actor/DevToolsProcessChild.sys.mjs
new file mode 100644
index 0000000000..9e8ad64eea
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+++ b/devtools/server/connectors/js-process-actor/DevToolsProcessChild.sys.mjs
@@ -0,0 +1,362 @@
+/* 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/. */
+
+import { EventEmitter } from "resource://gre/modules/EventEmitter.sys.mjs";
+
+const lazy = {};
+ChromeUtils.defineESModuleGetters(
+  lazy,
+  {
+    releaseDistinctSystemPrincipalLoader:
+      "resource://devtools/shared/loader/DistinctSystemPrincipalLoader.sys.mjs",
+    useDistinctSystemPrincipalLoader:
+      "resource://devtools/shared/loader/DistinctSystemPrincipalLoader.sys.mjs",
+  },
+  { global: "contextual" }
+);
+
+// Name of the attribute into which we save data in `sharedData` object.
+const SHARED_DATA_KEY_NAME = "DevTools:watchedPerWatcher";
+
+// If true, log info about DOMProcess's being created.
+const DEBUG = false;
+
+/**
+ * Print information about operation being done against each content process.
+ *
+ * @param {nsIDOMProcessChild} domProcessChild
+ *        The process for which we should log a message.
+ * @param {String} message
+ *        Message to log.
+ */
+function logDOMProcess(domProcessChild, message) {
+  if (!DEBUG) {
+    return;
+  }
+  dump(" [pid:" + domProcessChild + "] " + message + "\n");
+}
+
+export class DevToolsProcessChild extends JSProcessActorChild {
+  constructor() {
+    super();
+
+    // The map is indexed by the Watcher Actor ID.
+    // The values are objects containing the following properties:
+    // - connection: the DevToolsServerConnection itself
+    // - actor: the ContentProcessTargetActor instance
+    this._connections = new Map();
+
+    this._onConnectionChange = this._onConnectionChange.bind(this);
+    EventEmitter.decorate(this);
+  }
+
+  instantiate() {
+    const { sharedData } = Services.cpmm;
+    const watchedDataByWatcherActor = sharedData.get(SHARED_DATA_KEY_NAME);
+    if (!watchedDataByWatcherActor) {
+      throw new Error(
+        "Request to instantiate the target(s) for the process, but `sharedData` is empty about watched targets"
+      );
+    }
+
+    // Create one Target actor for each prefix/client which listen to processes
+    for (const [watcherActorID, sessionData] of watchedDataByWatcherActor) {
+      const { connectionPrefix } = sessionData;
+
+      if (sessionData.targets?.includes("process")) {
+        this._createTargetActor(watcherActorID, connectionPrefix, sessionData);
+      }
+    }
+  }
+
+  /**
+   * Instantiate a new ProcessTarget for the given connection.
+   *
+   * @param String watcherActorID
+   *        The ID of the WatcherActor who requested to observe and create these target actors.
+   * @param String parentConnectionPrefix
+   *        The prefix of the DevToolsServerConnection of the Watcher Actor.
+   *        This is used to compute a unique ID for the target actor.
+   * @param Object sessionData
+   *        All data managed by the Watcher Actor and WatcherRegistry.sys.mjs, containing
+   *        target types, resources types to be listened as well as breakpoints and any
+   *        other data meant to be shared across processes and threads.
+   */
+  _createTargetActor(watcherActorID, parentConnectionPrefix, sessionData) {
+    // This method will be concurrently called from `observe()` and `DevToolsProcessParent:instantiate-already-available`
+    // When the JSprocessActor initializes itself and when the watcher want to force instantiating existing targets.
+    // Simply ignore the second call as there is nothing to return, neither to wait for as this method is synchronous.
+    if (this._connections.has(watcherActorID)) {
+      return;
+    }
+
+    // Compute a unique prefix, just for this DOM Process,
+    // which will be used to create a JSWindowActorTransport pair between content and parent processes.
+    // This is slightly hacky as we typicaly compute Prefix and Actor ID via `DevToolsServerConnection.allocID()`,
+    // but here, we can't have access to any DevTools connection as we are really early in the content process startup
+    // XXX: nsIDOMProcessChild's childID should be unique across processes, I think. So that should be safe?
+    // (this.manager == nsIDOMProcessChild interface)
+    // Ensure appending a final slash, otherwise the prefix may be the same between childID 1 and 10...
+    const forwardingPrefix =
+      parentConnectionPrefix + "contentProcess" + this.manager.childID + "/";
+
+    logDOMProcess(
+      this.manager,
+      "Instantiate ContentProcessTarget with prefix: " + forwardingPrefix
+    );
+
+    const { connection, targetActor } = this._createConnectionAndActor(
+      watcherActorID,
+      forwardingPrefix,
+      sessionData
+    );
+    this._connections.set(watcherActorID, {
+      connection,
+      actor: targetActor,
+    });
+
+    // Immediately queue a message for the parent process,
+    // in order to ensure that the JSWindowActorTransport is instantiated
+    // before any packet is sent from the content process.
+    // As the order of messages is guaranteed to be delivered in the order they
+    // were queued, we don't have to wait for anything around this sendAsyncMessage call.
+    // In theory, the ContentProcessTargetActor may emit events in its constructor.
+    // If it does, such RDP packets may be lost. But in practice, no events
+    // are emitted during its construction. Instead the frontend will start
+    // the communication first.
+    this.sendAsyncMessage("DevToolsProcessChild:connectFromContent", {
+      watcherActorID,
+      forwardingPrefix,
+      actor: targetActor.form(),
+    });
+
+    // Pass initialization data to the target actor
+    for (const type in sessionData) {
+      // `sessionData` will also contain `browserId` as well as entries with empty arrays,
+      // which shouldn't be processed.
+      const entries = sessionData[type];
+      if (!Array.isArray(entries) || !entries.length) {
+        continue;
+      }
+      targetActor.addOrSetSessionDataEntry(
+        type,
+        sessionData[type],
+        false,
+        "set"
+      );
+    }
+  }
+
+  _destroyTargetActor(watcherActorID, isModeSwitching) {
+    const connectionInfo = this._connections.get(watcherActorID);
+    // This connection has already been cleaned?
+    if (!connectionInfo) {
+      throw new Error(
+        `Trying to destroy a target actor that doesn't exists, or has already been destroyed. Watcher Actor ID:${watcherActorID}`
+      );
+    }
+    connectionInfo.connection.close({ isModeSwitching });
+    this._connections.delete(watcherActorID);
+    if (this._connections.size == 0) {
+      this.didDestroy({ isModeSwitching });
+    }
+  }
+
+  _createConnectionAndActor(watcherActorID, forwardingPrefix, sessionData) {
+    if (!this.loader) {
+      this.loader = lazy.useDistinctSystemPrincipalLoader(this);
+    }
+    const { DevToolsServer } = this.loader.require(
+      "devtools/server/devtools-server"
+    );
+
+    const { ContentProcessTargetActor } = this.loader.require(
+      "devtools/server/actors/targets/content-process"
+    );
+
+    DevToolsServer.init();
+
+    // For browser content toolbox, we do need a regular root actor and all tab
+    // actors, but don't need all the "browser actors" that are only useful when
+    // debugging the parent process via the browser toolbox.
+    DevToolsServer.registerActors({ target: true });
+    DevToolsServer.on("connectionchange", this._onConnectionChange);
+
+    const connection = DevToolsServer.connectToParentWindowActor(
+      this,
+      forwardingPrefix,
+      "DevToolsProcessChild:packet"
+    );
+
+    // Create the actual target actor.
+    const targetActor = new ContentProcessTargetActor(connection, {
+      sessionContext: sessionData.sessionContext,
+    });
+    // There is no root actor in content processes and so
+    // the target actor can't be managed by it, but we do have to manage
+    // the actor to have it working and be registered in the DevToolsServerConnection.
+    // We make it manage itself and become a top level actor.
+    targetActor.manage(targetActor);
+
+    const form = targetActor.form();
+    targetActor.once("destroyed", options => {
+      // This will destroy the content process one
+      this._destroyTargetActor(watcherActorID, options.isModeSwitching);
+      // And this will destroy the parent process one
+      try {
+        this.sendAsyncMessage("DevToolsProcessChild:destroy", {
+          actors: [
+            {
+              watcherActorID,
+              form,
+            },
+          ],
+          options,
+        });
+      } catch (e) {
+        // Ignore exception when the JSProcessActorChild has already been destroyed.
+        // We often try to emit this message while the process is being destroyed,
+        // but sendAsyncMessage doesn't have time to complete and throws.
+        if (
+          !e.message.includes("JSProcessActorChild cannot send at the moment")
+        ) {
+          throw e;
+        }
+      }
+    });
+
+    return { connection, targetActor };
+  }
+
+  /**
+   * Destroy the server once its last connection closes. Note that multiple
+   * frame scripts may be running in parallel and reuse the same server.
+   */
+  _onConnectionChange() {
+    if (this._destroyed) {
+      return;
+    }
+    this._destroyed = true;
+
+    const { DevToolsServer } = this.loader.require(
+      "devtools/server/devtools-server"
+    );
+
+    // Only destroy the server if there is no more connections to it. It may be
+    // used to debug another tab running in the same process.
+    if (DevToolsServer.hasConnection() || DevToolsServer.keepAlive) {
+      return;
+    }
+
+    DevToolsServer.off("connectionchange", this._onConnectionChange);
+    DevToolsServer.destroy();
+  }
+
+  /**
+   * Supported Queries
+   */
+
+  sendPacket(packet, prefix) {
+    this.sendAsyncMessage("DevToolsProcessChild:packet", { packet, prefix });
+  }
+
+  /**
+   * JsWindowActor API
+   */
+
+  async sendQuery(msg, args) {
+    try {
+      const res = await super.sendQuery(msg, args);
+      return res;
+    } catch (e) {
+      console.error("Failed to sendQuery in DevToolsProcessChild", msg);
+      console.error(e.toString());
+      throw e;
+    }
+  }
+
+  receiveMessage(message) {
+    switch (message.name) {
+      case "DevToolsProcessParent:instantiate-already-available": {
+        const { watcherActorID, connectionPrefix, sessionData } = message.data;
+        return this._createTargetActor(
+          watcherActorID,
+          connectionPrefix,
+          sessionData
+        );
+      }
+      case "DevToolsProcessParent:destroy": {
+        const { watcherActorID, isModeSwitching } = message.data;
+        return this._destroyTargetActor(watcherActorID, isModeSwitching);
+      }
+      case "DevToolsProcessParent:addOrSetSessionDataEntry": {
+        const { watcherActorID, type, entries, updateType } = message.data;
+        return this._addOrSetSessionDataEntry(
+          watcherActorID,
+          type,
+          entries,
+          updateType
+        );
+      }
+      case "DevToolsProcessParent:removeSessionDataEntry": {
+        const { watcherActorID, type, entries } = message.data;
+        return this._removeSessionDataEntry(watcherActorID, type, entries);
+      }
+      case "DevToolsProcessParent:packet":
+        return this.emit("packet-received", message);
+      default:
+        throw new Error(
+          "Unsupported message in DevToolsProcessParent: " + message.name
+        );
+    }
+  }
+
+  _getTargetActorForWatcherActorID(watcherActorID) {
+    const connectionInfo = this._connections.get(watcherActorID);
+    return connectionInfo?.actor;
+  }
+
+  _addOrSetSessionDataEntry(watcherActorID, type, entries, updateType) {
+    const targetActor = this._getTargetActorForWatcherActorID(watcherActorID);
+    if (!targetActor) {
+      throw new Error(
+        `No target actor for this Watcher Actor ID:"${watcherActorID}"`
+      );
+    }
+    return targetActor.addOrSetSessionDataEntry(
+      type,
+      entries,
+      false,
+      updateType
+    );
+  }
+
+  _removeSessionDataEntry(watcherActorID, type, entries) {
+    const targetActor = this._getTargetActorForWatcherActorID(watcherActorID);
+    // By the time we are calling this, the target may already have been destroyed.
+    if (!targetActor) {
+      return null;
+    }
+    return targetActor.removeSessionDataEntry(type, entries);
+  }
+
+  observe(subject, topic) {
+    if (topic === "init-devtools-content-process-actor") {
+      // This is triggered by the process actor registration and some code in process-helper.js
+      // which defines a unique topic to be observed
+      this.instantiate();
+    }
+  }
+
+  didDestroy(options) {
+    for (const { connection } of this._connections.values()) {
+      connection.close(options);
+    }
+    this._connections.clear();
+    if (this.loader) {
+      lazy.releaseDistinctSystemPrincipalLoader(this);
+      this.loader = null;
+    }
+  }
+}