1 files changed, 124 insertions, 0 deletions
diff --git a/devtools/server/actors/watcher/WatchedDataHelpers.jsm b/devtools/server/actors/watcher/WatchedDataHelpers.jsm
new file mode 100644
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+++ b/devtools/server/actors/watcher/WatchedDataHelpers.jsm
@@ -0,0 +1,124 @@
+/* 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";
+
+/**
+ * Helper module alongside WatcherRegistry, which focus on updating the "watchedData" object.
+ * This object is shared across processes and threads and have to be maintained in all these runtimes.
+ */
+
+var EXPORTED_SYMBOLS = ["WatchedDataHelpers"];
+
+// List of all arrays stored in `watchedData`, which are replicated across processes and threads
+const SUPPORTED_DATA = {
+  BREAKPOINTS: "breakpoints",
+  RESOURCES: "resources",
+  TARGETS: "targets",
+};
+
+// Optional function, if data isn't a primitive data type in order to produce a key
+// for the given data entry
+const DATA_KEY_FUNCTION = {
+  [SUPPORTED_DATA.BREAKPOINTS]: function({
+    location: { sourceUrl, sourceId, line, column },
+  }) {
+    if (!sourceUrl && !sourceId) {
+      throw new Error(
+        `Breakpoints expect to have either a sourceUrl or a sourceId.`
+      );
+    }
+    if (sourceUrl && typeof sourceUrl != "string") {
+      throw new Error(
+        `Breakpoints expect to have sourceUrl string, got ${typeof sourceUrl} instead.`
+      );
+    }
+    // sourceId may be undefined for some sources keyed by URL
+    if (sourceId && typeof sourceId != "string") {
+      throw new Error(
+        `Breakpoints expect to have sourceId string, got ${typeof sourceId} instead.`
+      );
+    }
+    if (typeof line != "number") {
+      throw new Error(
+        `Breakpoints expect to have line number, got ${typeof line} instead.`
+      );
+    }
+    if (typeof column != "number") {
+      throw new Error(
+        `Breakpoints expect to have column number, got ${typeof column} instead.`
+      );
+    }
+    return `${sourceUrl}:${sourceId}:${line}:${column}`;
+  },
+};
+
+function idFunction(v) {
+  if (typeof v != "string") {
+    throw new Error(
+      `Expect data entry values to be string, or be using custom data key functions. Got ${typeof v} type instead.`
+    );
+  }
+  return v;
+}
+
+const WatchedDataHelpers = {
+  SUPPORTED_DATA,
+
+  /**
+   * Add new values to the shared "watchedData" object.
+   *
+   * @param Object watchedData
+   *               The data object to update.
+   * @param string type
+   *               The type of data to be added
+   * @param Array<Object> entries
+   *               The values to be added to this type of data
+   */
+  addWatchedDataEntry(watchedData, type, entries) {
+    const toBeAdded = [];
+    const keyFunction = DATA_KEY_FUNCTION[type] || idFunction;
+    for (const entry of entries) {
+      const alreadyExists = watchedData[type].some(existingEntry => {
+        return keyFunction(existingEntry) === keyFunction(entry);
+      });
+      if (!alreadyExists) {
+        toBeAdded.push(entry);
+      }
+    }
+    watchedData[type].push(...toBeAdded);
+  },
+
+  /**
+   * Remove values from the shared "watchedData" object.
+   *
+   * @param Object watchedData
+   *               The data object to update.
+   * @param string type
+   *               The type of data to be remove
+   * @param Array<Object> entries
+   *               The values to be removed from this type of data
+   * @return Boolean
+   *               True, if at least one entries existed and has been removed.
+   *               False, if none of the entries existed and none has been removed.
+   */
+  removeWatchedDataEntry(watchedData, type, entries) {
+    let includesAtLeastOne = false;
+    const keyFunction = DATA_KEY_FUNCTION[type] || idFunction;
+    for (const entry of entries) {
+      const idx = watchedData[type].findIndex(existingEntry => {
+        return keyFunction(existingEntry) === keyFunction(entry);
+      });
+      if (idx !== -1) {
+        watchedData[type].splice(idx, 1);
+        includesAtLeastOne = true;
+      }
+    }
+    if (!includesAtLeastOne) {
+      return false;
+    }
+
+    return true;
+  },
+};