Bug 409870

Description Mark Macdonald 2013-06-04 11:56:50 EDT

Libing has this code, which updates the "recent searches" pref:

> serviceRegistry.getService("orion.core.preference").getPreferences("/window/favorites").then(function(prefs) {
>     prefs.put("recentSearch", newSearches);  // put the new value
>     eventTarget.dispatchEvent({ type: "recentSearchesChanged" });
> });

The above code invokes an event handler, who tries to get the new pref value by doing this:

> serviceRegistry.getService("orion.core.preference").getPreferences("/window/favorites").then(function(prefs) {
>     var searches = prefs.get("recentSearch");    // doesn't get the new value
>     // ...
> });

The event handler receives a stale value for the "recentSearch" pref.

I didn't debug this, but I think it's because the getPreferences() call hands out a new Preferences instance every time, and the instances do not know about each other's pending changes until they get flushed to the back end store (or some other asynchronous event happens, whatever it is). This means you need to pass the actual Preferences object around to all clients, or they risk getting stale values.

It would be convenient if the pending changes were known to all Preferences instances. Is this feasible? It seems simpler than full blown cross-tab preferences (something we've discussed in the past) since everything is in the same window.