try custom lru cache

test/test-discover/2_compare_lru_caches.js

@@ -2,21 +2,48 @@ var path = require('path');
 var name = path.basename(__filename);
 var LRU = require('lru-cache');
 var MKC = require('mkc');
+var expect = require('expect.js');
+
+var customLRUCache = function(max) {
+  var data = {};
+  return {
+    get: function(key) {
+      var val = data[key];
+      if (typeof val !== 'undefined') {
+        // val is defined, so mark as "most recently used"
+        // by moving to back of data object using the fact
+        // that objects recall key order
+        //
+        // NB: object key order is only preserved for non-numerical keys
+        delete data[key];
+        data[key] = val;
+      }
+      return val;
+    },
+    set: function(key, val) {
+      data[key] = val;
+      var keys = Object.keys(data);
+      var deleteCount = keys.length - max;
+      for (var i = 0; i < deleteCount; i++) delete data[keys[i]];
+      // console.log(Object.keys(data).length);
+    }
+  }
+};
 
 describe(name, function() {
 
   context('multiple keys with lru-cache and key append', function() {
 
     before('create cache', function() {
       this.cache = LRU({
-        max: 10,
+        max: 100,
         maxAge: 0
       });
     });
 
-    it('processes 10000 entries with max 10', function() {
+    it('processes 100000 entries with max 100', function() {
 
-      for (var i = 0; i < 10000; i++) {
+      for (var i = 0; i < 100000; i++) {
         var key1 = '/some/average/string/length/' + i;
         var key2 = '/some/other/average/string/' + i;
 
@@ -35,12 +62,12 @@ describe(name, function() {
   context('multiple keys with multikey-cache', function() {
 
     before('create cache', function() {
-      this.cache = new MKC({max: 10});
+      this.cache = new MKC({max: 100});
     });
 
-    it('processes 10000 entries with max 10', function() {
+    it('processes 100000 entries with max 100', function() {
 
-      for (var i = 0; i < 10000; i++) {
+      for (var i = 0; i < 100000; i++) {
         var key1 = '/some/average/string/length/' + i;
         var key2 = '/some/other/average/string/' + i;
 
@@ -55,5 +82,66 @@ describe(name, function() {
   });
 
 
+  context('multiple keys with customLRUCache', function() {
+
+    before('create cache', function() {
+      this.cache = customLRUCache(100);
+    });
+
+    it('processes 100000 entries with max 100', function() {
+
+      for (var i = 0; i < 100000; i++) {
+        var key1 = '/some/average/string/length/' + i;
+        var key2 = '/some/other/average/string/' + i;
+
+        var key = key1 + '##' + key2;
+        var got = this.cache.get(key);
+        if (typeof got === 'undefined') {
+          this.cache.set(key, true);
+        }
+      }
+
+    });
+
+    it('set() works', function() {
+
+      var cache = customLRUCache(max = 3);
+
+      // add 4 entries, the first should be deleted
+
+      cache.set('/01', true);
+      cache.set('/02', true);
+      cache.set('/03', true);
+      cache.set('/04', true);
+
+      expect(cache.get('/01')).to.equal(undefined);
+      expect(cache.get('/02')).to.equal(true);
+      expect(cache.get('/03')).to.equal(true);
+      expect(cache.get('/04')).to.equal(true);
+
+    });
+
+    it('get() works', function() {
+
+      var cache = customLRUCache(max = 3);
+
+      cache.set('/01', true);
+      cache.set('/02', true);
+      cache.set('/03', true);
+
+      // use /01 so that it's most recently used
+      expect(cache.get('/01')).to.equal(true);
+
+      // create new entry should push off least recently used: /02
+      cache.set('/04', true);
+
+      expect(cache.get('/01')).to.equal(true);
+      expect(cache.get('/02')).to.equal(undefined);
+      expect(cache.get('/03')).to.equal(true);
+      expect(cache.get('/04')).to.equal(true);
+
+    });
+
+  });
 
 });