feat: Add a JS binding for MemoryPressureMonitor

.github/workflows/bs_electron_ci_ec2.yml

@@ -53,7 +53,7 @@ jobs:
 
       - name: Start EC2 runner
         id: start-ec2-runner
-        uses: brightsign/ec2-github-runner@0fa8b183dd4124fd191ccdbc48b68f0ea46a9634
+        uses: brightsign/ec2-github-runner@3ef5e07bd58c60757b26c39b8cf25f234df7b974
         with:
           mode: start
           github-app-private-key: ${{ secrets.GH_APP_PRIVATE_KEY }}
@@ -98,11 +98,11 @@ jobs:
           aws-region: ${{ inputs.aws_region }}
 
       - name: Stop EC2 runner
-        uses: brightsign/ec2-github-runner@0fa8b183dd4124fd191ccdbc48b68f0ea46a9634
+        uses: brightsign/ec2-github-runner@3ef5e07bd58c60757b26c39b8cf25f234df7b974
         with:
           mode: stop
           github-app-private-key: ${{ secrets.GH_APP_PRIVATE_KEY }}
           github-app-id: 287690
           label: ${{ needs.start-runner.outputs.label }}
           ec2-instance-id: ${{ needs.start-runner.outputs.ec2-instance-id }}
-          leave-ec2-instance-running:  ${{ inputs.leave_ec2_instance_running }}
+          leave-ec2-instance-running:  ${{ inputs.leave_ec2_instance_running }}

docs/api/memory-pressure-monitor.md

@@ -0,0 +1,80 @@
+# memoryPressureMonitor
+
+> Monitor and trigger system memory pressure events.
+
+Process: [Main](../glossary.md#main-process)
+
+## Events
+
+The `memoryPressureMonitor` module emits the following events:
+
+### Event: 'memory-pressure'
+
+Returns:
+
+* `level` string - The memory pressure level. Can be `moderate` or `critical`.
+
+Emitted when the system reports a change in memory pressure. This is an
+OS-level signal indicating that the system is running low on available memory.
+
+At the `moderate` level, modules should free buffers that are cheap to
+re-allocate and not immediately needed.
+
+At the `critical` level, modules should free all possible memory. The
+alternative is to be killed by the system, which means all memory will have to
+be re-created, plus the cost of a cold start.
+
+Apps may react by closing non-essential windows or tabs, clearing caches,
+dropping undo history, or other memory-saving measures.
+
+## Methods
+
+The `memoryPressureMonitor` module has the following methods:
+
+### `memoryPressureMonitor.getCurrentPressureLevel()`
+
+Returns `string` - The current memory pressure level. Can be `none`, `moderate`,
+or `critical`.
+
+Returns the memory pressure level last set via `notifyMemoryPressure()`. Defaults
+to `none` if no level has been set.
+
+### `memoryPressureMonitor.notifyMemoryPressure(level)`
+
+* `level` string - The pressure level to set. Must be `none`, `moderate`, or
+  `critical`.
+
+Broadcasts a memory pressure notification to all listeners in both the main
+process and all renderer processes. This causes Chromium internals (blink
+resource cache, V8 garbage collector, network cache, decoded image cache, etc.)
+to release memory as if the OS had reported memory pressure.
+
+When called with `none`, the level is stored (so `getCurrentPressureLevel()`
+reflects it) but no notification is broadcast, since Chromium does not support
+notifying "no pressure".
+
+Use this when your application knows that external resources held by the
+Electron process are causing system-wide memory pressure, and you want Electron
+to proactively release caches and run garbage collection across all processes.
+
+In the main process, this respects the notification-suppressed flag — if
+notifications are suppressed (e.g. during memory measurement), the main-process
+notification will be silently dropped. Renderer processes are always notified.
+
+```javascript
+const { memoryPressureMonitor } = require('electron')
+
+// Listen for OS memory pressure events
+memoryPressureMonitor.on('memory-pressure', (level) => {
+  console.log(`Memory pressure: ${level}`)
+  if (level === 'critical') {
+    // Close non-essential windows, drop caches, etc.
+  }
+})
+
+// Trigger memory pressure to force Electron to release caches
+memoryPressureMonitor.notifyMemoryPressure('critical')
+
+// Query current pressure level
+console.log(memoryPressureMonitor.getCurrentPressureLevel())
+```

filenames.auto.gni

@@ -27,6 +27,7 @@ auto_filenames = {
     "docs/api/incoming-message.md",
     "docs/api/ipc-main.md",
     "docs/api/ipc-renderer.md",
+    "docs/api/memory-pressure-monitor.md",
     "docs/api/menu-item.md",
     "docs/api/menu.md",
     "docs/api/message-channel-main.md",
@@ -206,6 +207,7 @@ auto_filenames = {
     "lib/browser/api/global-shortcut.ts",
     "lib/browser/api/in-app-purchase.ts",
     "lib/browser/api/ipc-main.ts",
+    "lib/browser/api/memory-pressure-monitor.ts",
     "lib/browser/api/menu-item-roles.ts",
     "lib/browser/api/menu-item.ts",
     "lib/browser/api/menu-utils.ts",

filenames.gni

@@ -289,6 +289,8 @@ filenames = {
     "shell/browser/api/electron_api_in_app_purchase.h",
     "shell/browser/api/electron_api_menu.cc",
     "shell/browser/api/electron_api_menu.h",
+    "shell/browser/api/electron_api_memory_pressure_monitor.cc",
+    "shell/browser/api/electron_api_memory_pressure_monitor.h",
     "shell/browser/api/electron_api_native_theme.cc",
     "shell/browser/api/electron_api_native_theme.h",
     "shell/browser/api/electron_api_net_log.cc",

lib/browser/api/memory-pressure-monitor.ts

@@ -0,0 +1,55 @@
+import { EventEmitter } from 'events';
+
+const {
+  createMemoryPressureMonitor
+} = process._linkedBinding('electron_browser_memory_pressure_monitor');
+
+class MemoryPressureMonitor extends EventEmitter {
+  #native: any;
+
+  constructor () {
+    super();
+    // Lazily create the native binding on first listener, following
+    // the powerMonitor pattern. This avoids creating a
+    // base::MemoryPressureListener until someone actually cares.
+    this.once('newListener', () => {
+      this.#native = createMemoryPressureMonitor();
+      this.#native.emit = this.emit.bind(this);
+    });
+  }
+
+  /**
+   * Returns the current memory pressure level reported by the OS.
+   * @returns {'none' | 'moderate' | 'critical'}
+   */
+  getCurrentPressureLevel (): 'none' | 'moderate' | 'critical' {
+    if (this.#native) {
+      return this.#native.getCurrentPressureLevel();
+    }
+    // If native binding hasn't been created yet, create it now
+    this.#native = createMemoryPressureMonitor();
+    this.#native.emit = this.emit.bind(this);
+    return this.#native.getCurrentPressureLevel();
+  }
+
+  /**
+   * Sets the memory pressure level. For 'moderate' and 'critical',
+   * broadcasts a notification to all listeners in this process and
+   * renderer processes. For 'none', records the level without
+   * broadcasting (Chromium does not accept none notifications).
+   *
+   * @param level - 'none' | 'moderate' | 'critical'
+   */
+  notifyMemoryPressure (level: 'none' | 'moderate' | 'critical'): void {
+    if (this.#native) {
+      this.#native.notifyMemoryPressure(level);
+      return;
+    }
+    // If native binding hasn't been created yet, create it now
+    this.#native = createMemoryPressureMonitor();
+    this.#native.emit = this.emit.bind(this);
+    this.#native.notifyMemoryPressure(level);
+  }
+}
+
+module.exports = new MemoryPressureMonitor();

lib/browser/api/module-list.ts

@@ -15,6 +15,7 @@ export const browserModuleList: ElectronInternal.ModuleEntry[] = [
   { name: 'globalShortcut', loader: () => require('./global-shortcut') },
   { name: 'ipcMain', loader: () => require('./ipc-main') },
   { name: 'inAppPurchase', loader: () => require('./in-app-purchase') },
+  { name: 'memoryPressureMonitor', loader: () => require('./memory-pressure-monitor') },
   { name: 'Menu', loader: () => require('./menu') },
   { name: 'MenuItem', loader: () => require('./menu-item') },
   { name: 'MessageChannelMain', loader: () => require('./message-channel') },

patches/chromium/.patches

@@ -195,9 +195,9 @@ add_switch_to_disable_font_matching_cache_os-14352.patch
 fix_overlay_strategy_for_html_pages_with_transparency_os-19250.patch
 feat_nexus-window_implement_setopacity_support_for_nexus_platform.patch
 ozone_nexus_implement_setfullscreen_for_nexuswindow_os-19899.patch
-enable_memory_pressure_monitoring_and_enable_for_renderer_process.patch
 fix_wayland_window_call_setwindowgeometry_for_position_updates.patch
 add_mse_support_to_brightsign_video_player_os-19598.patch
 feat_enable_hls_support_when_brightsign_media_player_is_enabled.patch
 feat_add_video_audio-codecs-supported_flag_support.patch
 brightsign_enable_viewport_options_when_viewport_enabled_os-20339.patch
+feat_enable_cross-process_memory_pressure_notification_on_all.patch