Bug 1743465: Extract Windows install information to a reusable module. r=nalexander

This is a re-post of https://phabricator.services.mozilla.com/D108662 with the performance bits noted there fixed.

Differential Revision: https://phabricator.services.mozilla.com/D135246

toolkit/components/telemetry/pings/UninstallPing.jsm

@@ -5,7 +5,15 @@
 
 "use strict";
 
-const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
+const { XPCOMUtils } = ChromeUtils.import(
+  "resource://gre/modules/XPCOMUtils.jsm"
+);
+
+XPCOMUtils.defineLazyModuleGetters(this, {
+  Services: "resource://gre/modules/Services.jsm",
+  WindowsInstallsInfo:
+    "resource://gre/modules/components-utils/WindowsInstallsInfo.jsm",
+});
 
 var EXPORTED_SYMBOLS = ["UninstallPing"];
 
@@ -24,81 +32,10 @@ var UninstallPing = {
    * Count other installs of this app, based on the values in the TaskBarIDs registry key.
    *
    */
-  getOtherInstallsCount(rootKey) {
+  getOtherInstallsCount() {
-    // This is somewhat more complicated than just counting the number of values on the key:
+    return WindowsInstallsInfo.getInstallPaths(
-    // 1) the same install can be listed in both HKCU and HKLM
+      this.MAX_OTHER_INSTALLS,
-    // 2) the current path may not be listed
+      new Set([Services.dirsvc.get("GreBinD", Ci.nsIFile).path])
-    //
+    ).size;
-    // The strategy is to add all paths to a Set (to deduplicate) and use that size.
-
-    // Add the names of the values under `rootKey\subKey` to `set`, until the set has `maxCount`.
-    // All strings are lower cased first, as Windows paths are not case-sensitive.
-    function collectValues(rootKey, wowFlag, subKey, set, maxCount) {
-      if (set.size >= maxCount) {
-        return;
-      }
-
-      const key = Cc["@mozilla.org/windows-registry-key;1"].createInstance(
-        Ci.nsIWindowsRegKey
-      );
-
-      try {
-        key.open(rootKey, subKey, key.ACCESS_READ | wowFlag);
-      } catch (_e) {
-        // The key may not exist, ignore.
-        // (nsWindowsRegKey::Open doesn't provide detailed error codes)
-        return;
-      }
-      const valueCount = key.valueCount;
-
-      try {
-        for (let i = 0; i < valueCount && set.size < maxCount; ++i) {
-          set.add(key.getValueName(i).toLowerCase());
-        }
-      } finally {
-        key.close();
-      }
-    }
-
-    const subKeyName = `Software\\Mozilla\\${Services.appinfo.name}\\TaskBarIDs`;
-
-    const paths = new Set();
-
-    // The current install path may not have a value in TaskBarIDs. It is simpler to
-    // pre-add it and always include it in the total, than to check for it everywhere and
-    // sometimes include it.
-    paths.add(Services.dirsvc.get("GreBinD", Ci.nsIFile).path.toLowerCase());
-
-    const initialPathsCount = paths.size;
-    const maxPathsCount = initialPathsCount + this.MAX_OTHER_INSTALLS;
-
-    // First collect from HKLM for both 32-bit and 64-bit installs regardless of the architecture
-    // of the current application.
-    for (const wowFlag of [
-      Ci.nsIWindowsRegKey.WOW64_32,
-      Ci.nsIWindowsRegKey.WOW64_64,
-    ]) {
-      collectValues(
-        Ci.nsIWindowsRegKey.ROOT_KEY_LOCAL_MACHINE,
-        wowFlag,
-        subKeyName,
-        paths,
-        maxPathsCount
-      );
-    }
-
-    // Then collect from HKCU.
-    // HKCU\Software is shared between 32 and 64 so nothing special is needed for WOW64,
-    // ref https://docs.microsoft.com/en-us/windows/win32/winprog64/shared-registry-keys
-    collectValues(
-      Ci.nsIWindowsRegKey.ROOT_KEY_CURRENT_USER,
-      0 /* wowFlag */,
-      subKeyName,
-      paths,
-      maxPathsCount
-    );
-
-    // Subtract our pre-added path, which is not an "other" install.
-    return paths.size - initialPathsCount;
   },
 };

toolkit/components/utils/WindowsInstallsInfo.jsm

@@ -0,0 +1,101 @@
+/* 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";
+
+var EXPORTED_SYMBOLS = ["WindowsInstallsInfo"];
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "Services",
+  "resource://gre/modules/Services.jsm"
+);
+
+var WindowsInstallsInfo = {
+  /**
+   * Retrieve install paths of this app, based on the values in the TaskBarIDs registry key.
+   *
+   * Installs from unarchived packages do not have a TaskBarID registry key and
+   * therefore won't appear in the result.
+   *
+   * @param {Number} [limit] Optional, maximum number of installation paths to count.
+            Defaults to 1024.
+   * @param {Set} [exclude] Optional, an Set of paths to exclude from the count.
+   * @returns {Set} Set of install paths, lower cased.
+   */
+  getInstallPaths(limit = 1024, exclude = new Set()) {
+    // This is somewhat more complicated than just collecting all values because
+    // the same install can be listed in both HKCU and HKLM.  The strategy is to
+    // add all paths to a Set to deduplicate.
+
+    const lcExclude = new Set();
+    exclude.forEach(p => lcExclude.add(p.toLowerCase()));
+
+    // Add the names of the values under `rootKey\subKey` to `set`.
+    // All strings are lower cased first, as Windows paths are not case-sensitive.
+    function collectValues(rootKey, wowFlag, subKey, set) {
+      const key = Cc["@mozilla.org/windows-registry-key;1"].createInstance(
+        Ci.nsIWindowsRegKey
+      );
+
+      try {
+        key.open(rootKey, subKey, key.ACCESS_READ | wowFlag);
+      } catch (_e) {
+        // The key may not exist, ignore.
+        // (nsWindowsRegKey::Open doesn't provide detailed error codes)
+        return;
+      }
+      const valueCount = key.valueCount;
+
+      try {
+        for (let i = 0; i < valueCount; ++i) {
+          const path = key.getValueName(i).toLowerCase();
+          if (!lcExclude.has(path)) {
+            set.add(path);
+          }
+          if (set.size >= limit) {
+            break;
+          }
+        }
+      } finally {
+        key.close();
+      }
+    }
+
+    const subKeyName = `Software\\Mozilla\\${Services.appinfo.name}\\TaskBarIDs`;
+
+    const paths = new Set();
+
+    // First collect from HKLM for both 32-bit and 64-bit installs regardless of the architecture
+    // of the current application.
+    for (const wowFlag of [
+      Ci.nsIWindowsRegKey.WOW64_32,
+      Ci.nsIWindowsRegKey.WOW64_64,
+    ]) {
+      collectValues(
+        Ci.nsIWindowsRegKey.ROOT_KEY_LOCAL_MACHINE,
+        wowFlag,
+        subKeyName,
+        paths
+      );
+      if (paths.size >= limit) {
+        break;
+      }
+    }
+
+    if (paths.size < limit) {
+      // Then collect from HKCU.
+      // HKCU\Software is shared between 32 and 64 so nothing special is needed for WOW64,
+      // ref https://docs.microsoft.com/en-us/windows/win32/winprog64/shared-registry-keys
+      collectValues(
+        Ci.nsIWindowsRegKey.ROOT_KEY_CURRENT_USER,
+        0 /* wowFlag */,
+        subKeyName,
+        paths
+      );
+    }
+
+    return paths;
+  },
+};

toolkit/components/utils/moz.build

@@ -18,6 +18,7 @@ EXTRA_JS_MODULES["components-utils"] = [
     "mozjexl.js",
     "PreferenceFilters.jsm",
     "Sampling.jsm",
+    "WindowsInstallsInfo.jsm",
     "WindowsVersionInfo.jsm",
 ]