This project contains the implementation of the Firefox brwoser.memory API.

Returns a promise that will resolve to an object containing memory details for each process. Each process is identified by it's PID, except for the main process which is labeled as "Parent." Currently only rss and uss are supported.

{
  "Parent":
   {
     "uss": 1234,
     "rss": 4567
   },
   "67890":
   {
     "uss": 1234,
     "rss": 4567
   }
}

An event that is triggered when low memory is detected. This can be used to proactively clear caches and attempt to reduce overall memory used by your WebExtension. Examples:

const callback = (data) => { console.log(`low memory: ${data}`); }

// register for the event
browser.memory.onLowMemory.addListener(callback);

// unregister from the event
browser.memory.onLowMemory.removeListener(callback);

Note: This was lifted from the logins experiment, there might be a better way to do things.

1. From a mozilla-central source tree, create a symlink for test/test_ext_memory.js in the webextensions xpcshell directory with the command:

   ln -s (path/to/this/repo)/test/test_ext_memory.js toolkit/components/extensions/test/xpcshell

2. Add the following line to toolkit/components/extensions/test/xpcshell/xpcshell.ini:

   [test_ext_memory.js]

3. Re-build the test database (./mach build or your favorite more targetted variant)

4. Run the test:

   ./mach test toolkit/components/extensions/test/xpcshell/test_ext_memory.js