Plugin API » Interfaces » InterRuntimeSignal

InterRuntimeSignal interface

A JavaScript object implementing the InterRuntimeSignal interface represents a named signal which can be delivered to all current JavaScript runtimes. It is intended for invalidating small caches implemented by runtimes.

If the cache is likely to be invalidated very infrequently, you could use O.reloadJavaScriptRuntimes() instead.

Construction

Use O.interRuntimeSignal(), passing in a name and a “signal function” which will be called when check() is called on a signalled object.

Usage

To implement a simple cache which can be invalidated by any active JavaScript runtime, use code like:

    // Functions implementing interface to cache object
    var getCache, invalidateCache;

    // Prevent cache being directly accessed using anon function
    (function() {
        // Cache object and signal to invalidate
        var cache = {};
        var invalidate = O.interRuntimeSignal("invalidate_test_cache",
            function() {
                cache = {};
            }
        );

        // Expose function to get the cache object, checking that
        // it hasn't been invalidated by another runtime.
        getCache = function(name) {
            invalidate.check();
            return cache;
        };

        // Expose function to invalidate cache
        invalidateCache = function() {
            invalidate.signal();
            // cache will be empty, as signal function has been called
        };
    })();

Interface

function signal()

Send the named signal to all other current JavaScript plugins. The signal function will be called in this runtime before the signal() function returns, and in all other runtimes the next time check() function is called.

function check()

Efficiently check whether this signal object is signalled, and if so, call the signal function then set this object to the unsignalled state.