feat($cacheFactory): add general purpose $cacheFactory service

Author: IgorMinar

Rakefile

@@ -16,6 +16,7 @@ ANGULAR = [
   'src/filters.js',
   'src/formatters.js',
   'src/validators.js',
+  'src/service/cacheFactory.js',
   'src/service/cookieStore.js',
   'src/service/cookies.js',
   'src/service/defer.js',

jsTestDriver-coverage.conf

@@ -19,6 +19,7 @@ load:
   - src/filters.js
   - src/formatters.js
   - src/validators.js
+  - src/service/cacheFactory.js
   - src/service/cookieStore.js
   - src/service/cookies.js
   - src/service/defer.js

jsTestDriver-jquery.conf

@@ -19,6 +19,7 @@ load:
   - src/filters.js
   - src/formatters.js
   - src/validators.js
+  - src/service/cacheFactory.js
   - src/service/cookieStore.js
   - src/service/cookies.js
   - src/service/defer.js

jsTestDriver-perf.conf

@@ -17,6 +17,7 @@ load:
   - src/filters.js
   - src/formatters.js
   - src/validators.js
+  - src/service/cacheFactory.js
   - src/service/cookieStore.js
   - src/service/cookies.js
   - src/service/defer.js

jsTestDriver.conf

@@ -19,6 +19,7 @@ load:
   - src/filters.js
   - src/formatters.js
   - src/validators.js
+  - src/service/cacheFactory.js
   - src/service/cookieStore.js
   - src/service/cookies.js
   - src/service/defer.js

src/angular-bootstrap.js

@@ -103,6 +103,7 @@
 
              // Extension points
 
+             'service/cacheFactory.js',
              'service/cookieStore.js',
              'service/cookies.js',
              'service/defer.js',

src/service/cacheFactory.js

@@ -0,0 +1,151 @@
+/**
+ * @workInProgress
+ * @ngdoc service
+ * @name angular.service.$cacheFactory
+ *
+ * @description
+ * Factory that constructs cache objects.
+ *
+ *
+ * @param {string} cacheId Name or id of the newly created cache.
+ * @param {object=} options Options object that specifies the cache behavior. Properties:
+ *
+ *   - `{number=}` `capacity` — turns the cache into LRU cache.
+ *
+ * @returns {object} Newly created cache object with the following set of methods:
+ *
+ * - `{string}` `id()` — Returns id or name of the cache.
+ * - `{number}` `size()` — Returns number of items currently in the cache
+ * - `{void}` `put({string} key, {*} value)` — Puts a new key-value pair into the cache
+ * - `{(*}} `get({string} key) — Returns cached value for `key` or undefined for cache miss.
+ * - `{void}` `remove{string} key) — Removes a key-value pair from the cache.
+ * - `{void}` `removeAll() — Removes all cached values.
+ *
+ */
+angularServiceInject('$cacheFactory', function() {
+
+  var caches = {};
+
+  function cacheFactory(cacheId, options) {
+    if (cacheId in caches) {
+      throw Error('cacheId ' + cacheId + ' taken');
+    }
+
+    var size = 0,
+        stats = extend({}, options, {id: cacheId}),
+        data = {},
+        capacity = (options && options.capacity) || Number.MAX_VALUE,
+        lruHash = {},
+        freshEnd = null,
+        staleEnd = null;
+
+    return caches[cacheId] = {
+
+      put: function(key, value) {
+        var lruEntry = lruHash[key] || (lruHash[key] = {key: key});
+
+        refresh(lruEntry);
+
+        if (isUndefined(value)) return;
+        if (!(key in data)) size++;
+        data[key] = value;
+
+        if (size > capacity) {
+          this.remove(staleEnd.key);
+        }
+      },
+
+
+      get: function(key) {
+        var lruEntry = lruHash[key];
+
+        if (!lruEntry) return;
+
+        refresh(lruEntry);
+
+        return data[key];
+      },
+
+
+      remove: function(key) {
+        var lruEntry = lruHash[key];
+
+        if (lruEntry == freshEnd) freshEnd = lruEntry.p;
+        if (lruEntry == staleEnd) staleEnd = lruEntry.n;
+        link(lruEntry.n,lruEntry.p);
+
+        delete lruHash[key];
+        delete data[key];
+        size--;
+      },
+
+
+      removeAll: function() {
+        data = {};
+        size = 0;
+        lruHash = {};
+        freshEnd = staleEnd = null;
+      },
+
+
+      destroy: function() {
+        data = null;
+        stats = null;
+        lruHash = null;
+        delete caches[cacheId];
+      },
+
+
+      info: function() {
+        return extend({}, stats, {size: size});
+      }
+    };
+
+
+    /**
+     * makes the `entry` the freshEnd of the LRU linked list
+     */
+    function refresh(entry) {
+      if (entry != freshEnd) {
+        if (!staleEnd) {
+          staleEnd = entry;
+        } else if (staleEnd == entry) {
+          staleEnd = entry.n;
+        }
+
+        link(entry.n, entry.p);
+        link(entry, freshEnd);
+        freshEnd = entry;
+        freshEnd.n = null;
+      }
+    }
+
+
+    /**
+     * bidirectionally links two entries of the LRU linked list
+     */
+    function link(nextEntry, prevEntry) {
+      if (nextEntry != prevEntry) {
+        if (nextEntry) nextEntry.p = prevEntry; //p stands for previous, 'prev' didn't minify
+        if (prevEntry) prevEntry.n = nextEntry; //n stands for next, 'next' didn't minify
+      }
+    }
+  }
+
+
+  cacheFactory.info = function() {
+    var info = {};
+    forEach(caches, function(cache, cacheId) {
+      info[cacheId] = cache.info();
+    });
+    return info;
+  };
+
+
+  cacheFactory.get = function(cacheId) {
+    return caches[cacheId];
+  };
+
+
+  return cacheFactory;
+});