5dd58142cb
The old LRU implementation stored a list's indices to reference items in that list, but deletions from the list made indices point to the wrong slot. Functionally, it meant that deleted slots were not guaranteed to be the oldest slot. Using a linked list fixes that.
138 lines
4.6 KiB
JavaScript
138 lines
4.6 KiB
JavaScript
var LRU = require('../lib/lru-cache.js');
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module.exports = [
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["should support being called without new", function(done, assert) {
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var cache = LRU(1);
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assert(cache instanceof LRU);
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done();
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}],
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["should support a zero capacity", function(done, assert) {
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var cache = new LRU(0);
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cache.set('key', 'value');
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assert.equal(cache.cache.size, 0);
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done();
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}],
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["should support a one capacity", function(done, assert) {
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var cache = new LRU(1);
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cache.set('key1', 'value1');
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assert.equal(cache.cache.size, 1);
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assert.equal(cache.newest, cache.cache.get('key1'));
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assert.equal(cache.oldest, cache.cache.get('key1'));
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cache.set('key2', 'value2');
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assert.equal(cache.cache.size, 1);
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assert.equal(cache.newest, cache.cache.get('key2'));
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assert.equal(cache.oldest, cache.cache.get('key2'));
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assert.equal(cache.get('key1'), undefined);
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assert.equal(cache.get('key2'), 'value2');
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done();
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}],
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["should remove the oldest element when reaching capacity",
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function(done, assert) {
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var cache = new LRU(2);
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cache.set('key1', 'value1');
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cache.set('key2', 'value2');
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cache.set('key3', 'value3');
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var slot1 = cache.cache.get('key1');
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var slot2 = cache.cache.get('key2');
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var slot3 = cache.cache.get('key3');
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assert.equal(cache.cache.size, 2);
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assert.equal(cache.oldest, slot2);
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assert.equal(cache.newest, slot3);
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assert.equal(slot2.older, null);
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assert.equal(slot2.newer, slot3);
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assert.equal(slot3.older, slot2);
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assert.equal(slot3.newer, null);
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assert.equal(cache.cache.get('key1'), undefined);
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assert.equal(cache.get('key1'), undefined);
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assert.equal(cache.get('key2'), 'value2');
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assert.equal(cache.get('key3'), 'value3');
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done();
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}],
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["should make sure that resetting a key in cache makes it newest",
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function(done, assert) {
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var cache = new LRU(2);
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cache.set('key', 'value');
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cache.set('key2', 'value2');
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assert.equal(cache.oldest, cache.cache.get('key'));
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assert.equal(cache.newest, cache.cache.get('key2'));
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cache.set('key', 'value');
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assert.equal(cache.oldest, cache.cache.get('key2'));
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assert.equal(cache.newest, cache.cache.get('key'));
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done();
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}],
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["should make sure that getting a key in cache makes it newest",
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function(done, assert) {
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// When the key is oldest.
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var cache = new LRU(2);
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cache.set('key1', 'value1');
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cache.set('key2', 'value2');
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var slot1 = cache.cache.get('key1');
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var slot2 = cache.cache.get('key2');
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assert.equal(cache.oldest, slot1);
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assert.equal(cache.newest, slot2);
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assert.equal(slot1.older, null);
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assert.equal(slot1.newer, slot2);
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assert.equal(slot2.older, slot1);
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assert.equal(slot2.newer, null);
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assert.equal(cache.get('key1'), 'value1');
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var slot1 = cache.cache.get('key1');
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var slot2 = cache.cache.get('key2');
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assert.equal(cache.oldest, slot2);
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assert.equal(cache.newest, slot1);
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assert.equal(slot2.older, null);
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assert.equal(slot2.newer, slot1);
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assert.equal(slot1.older, slot2);
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assert.equal(slot1.newer, null);
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// When the key is newest.
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cache = new LRU(2);
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cache.set('key1', 'value1');
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cache.set('key2', 'value2');
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assert.equal(cache.get('key2'), 'value2');
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var slot1 = cache.cache.get('key1');
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var slot2 = cache.cache.get('key2');
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assert.equal(cache.oldest, slot1);
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assert.equal(cache.newest, slot2);
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assert.equal(slot1.older, null);
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assert.equal(slot1.newer, slot2);
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assert.equal(slot2.older, slot1);
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assert.equal(slot2.newer, null);
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// When the key is in the middle.
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cache = new LRU(3);
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cache.set('key1', 'value1');
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cache.set('key2', 'value2');
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cache.set('key3', 'value3');
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var slot1 = cache.cache.get('key1');
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var slot2 = cache.cache.get('key2');
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var slot3 = cache.cache.get('key3');
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assert.equal(cache.oldest, slot1);
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assert.equal(cache.newest, slot3);
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assert.equal(slot1.older, null);
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assert.equal(slot1.newer, slot2);
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assert.equal(slot2.older, slot1);
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assert.equal(slot2.newer, slot3);
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assert.equal(slot3.older, slot2);
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assert.equal(slot3.newer, null);
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assert.equal(cache.get('key2'), 'value2');
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var slot1 = cache.cache.get('key1');
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var slot2 = cache.cache.get('key2');
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var slot3 = cache.cache.get('key3');
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assert.equal(cache.oldest, slot1);
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assert.equal(cache.newest, slot2);
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assert.equal(slot1.older, null);
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assert.equal(slot1.newer, slot3);
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assert.equal(slot3.older, slot1);
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assert.equal(slot3.newer, slot2);
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assert.equal(slot2.older, slot3);
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assert.equal(slot2.newer, null);
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done();
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}],
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];
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