lru-cache - npm Package Compare versions

Comparing version 1.0.6 to 1.1.0

lib/lru-cache.js

@@ -14,6 +14,17 @@ ;(function () { // closure for web browsers
 
-function LRUCache (maxLength) {
+function naiveLength () { return 1 }
+
+function LRUCache (maxLength, lengthCalculator) {
   if (!(this instanceof LRUCache)) {
-    return new LRUCache(maxLength)
+    return new LRUCache(maxLength, lengthCalculator)
   }
+
+  if (typeof lengthCalculator !== "function") {
+    lengthCalculator = naiveLength
+  }
+  if (!maxLength || !(typeof maxLength === "number") || maxLength <= 0 ) {
+    maxLength = Infinity
+  }
+
+
   var cache = {} // hash of items by key
@@ -24,3 +35,5 @@ , lruList = {} // list of items in order of use recency
     , length = 0 // number of items in the list
+    , itemCount = 0
 
+
   // resize the cache when the maxLength changes.
@@ -39,4 +52,26 @@ Object.defineProperty(this, "maxLength",
 
-  this.maxLength = maxLength
+  // resize the cache when the lengthCalculator changes.
+  Object.defineProperty(this, "lengthCalculator",
+    { set : function (lC) {
+        if (typeof lC !== "function") {
+          lengthCalculator = naiveLength
+          length = itemCount
+          Object.keys(cache).forEach(function (key) {
+            cache[key].length = 1
+          })
+        } else {
+          lengthCalculator = lC
+          length = 0
+          Object.keys(cache).forEach(function (key) {
+            cache[key].length = lengthCalculator(cache[key].value)
+            length += cache[key].length
+          })
+        }
 
+        if (length > maxLength) trim()
+      }
+    , get : function () { return lengthCalculator }
+    , enumerable : true
+    })
+
   Object.defineProperty(this, "length",
@@ -47,2 +82,8 @@ { get : function () { return length }
 
+
+  Object.defineProperty(this, "itemCount",
+    { get : function () { return itemCount }
+    , enumerable : true
+    })
+
   this.reset = function () {
@@ -54,2 +95,3 @@ cache = {}
     length = 0
+    itemCount = 0
   }
@@ -67,7 +109,14 @@
       cache[key].value = value
-      return undefined
+      return
     }
-    var hit = {key:key, value:value, lu:mru++}
+
+    var hit = {key:key, value:value, lu:mru++, length:lengthCalculator(value)}
+
+    // oversized objects fall out of cache automatically.
+    if (hit.length > maxLength) return
+
+    length += hit.length
     lruList[hit.lu] = cache[key] = hit
-    length ++
+    itemCount ++
+
     if (length > maxLength) trim()
@@ -77,3 +126,3 @@ }
   this.get = function (key) {
-    if (!hOP(cache, key)) return undefined
+    if (!hOP(cache, key)) return
     var hit = cache[key]
@@ -88,3 +137,3 @@ delete lruList[hit.lu]
   this.del = function (key) {
-    if (!hOP(cache, key)) return undefined
+    if (!hOP(cache, key)) return
     var hit = cache[key]
@@ -94,3 +143,4 @@ delete cache[key]
     if (hit.lu === lru) lruWalk()
-    length --
+    length -= hit.length
+    itemCount --
   }
@@ -100,13 +150,13 @@
     // lru has been deleted, hop up to the next hit.
-    lru = Object.keys(lruList).shift()
+    lru = Object.keys(lruList)[0]
   }
 
   function trim () {
-    if (length <= maxLength) return undefined
-    var prune = Object.keys(lruList).slice(0, length - maxLength)
-    for (var i = 0, l = (length - maxLength); i < l; i ++) {
+    if (length <= maxLength) return
+    var prune = Object.keys(lruList)
+    for (var i = 0; i < prune.length && length > maxLength; i ++) {
+      length -= lruList[prune[i]].length
       delete cache[ lruList[prune[i]].key ]
       delete lruList[prune[i]]
     }
-    length = maxLength
     lruWalk()
@@ -113,0 +163,0 @@ }

package.json

 { "name": "lru-cache"
 , "description": "A cache object that deletes the least-recently-used items."
-, "version": "1.0.6"
+, "version": "1.1.0"
 , "author": "Isaac Z. Schlueter <[e-mail]>"
@@ -8,3 +8,3 @@ , "scripts": { "test": "tap test" }
 , "repository": "git://github.com/isaacs/node-lru-cache.git"
-, "devDependencies": { "tap": "0" }
+, "devDependencies": { "tap": "" }
 , "license":
@@ -11,0 +11,0 @@ { "type": "MIT"

README.md

@@ -8,3 +8,10 @@ # lru cache
     var LRU = require("lru-cache")
-      , cache = LRU(10) // max 10 items. default = Infinity
+      , cache = LRU(10, // max length. default = Infinity
+                    // calculate how "big" each item is
+                    //
+                    // defaults to function(){return 1}, ie, just limit
+                    // the item count, without any knowledge as to their
+                    // relative size.
+                    function (item) { return item.length })
+
     cache.set("key", "value")
@@ -15,2 +22,7 @@ cache.get("key") // "value"
 
+If you put more stuff in it, then items will fall out.
+
+If you try to put an oversized thing in it, then it'll fall out right
+away.
+
 RTFS for more info.

test/basic.js

@@ -1,5 +0,5 @@
-var test = require('tap').test
-  , LRU = require('../')
+var test = require("tap").test
+  , LRU = require("../")
 
-test('basic', function (t) {
+test("basic", function (t) {
   var cache = new LRU(10)
@@ -14,3 +14,3 @@ cache.set("key", "value")
 
-test('least recently set', function (t) {
+test("least recently set", function (t) {
   var cache = new LRU(2)
@@ -26,3 +26,3 @@ cache.set("a", "A")
 
-test('lru recently gotten', function (t) {
+test("lru recently gotten", function (t) {
   var cache = new LRU(2)
@@ -39,3 +39,3 @@ cache.set("a", "A")
 
-test('del', function (t) {
+test("del", function (t) {
   var cache = new LRU(2)
@@ -48,3 +48,3 @@ cache.set("a", "A")
 
-test('maxLength', function (t) {
+test("maxLength", function (t) {
   var cache = new LRU(3)
@@ -87,3 +87,3 @@
 
-test('reset', function (t) {
+test("reset", function (t) {
   var cache = new LRU(10)
@@ -100,5 +100,6 @@ cache.set("a", "A")
 
+
 // Note: `<cache>.dump()` is a debugging tool only. No guarantees are made
 // about the format/layout of the response.
-test('dump', function (t) {
+test("dump", function (t) {
   var cache = new LRU(10)
@@ -108,6 +109,6 @@ var d = cache.dump();
   cache.set("a", "A")
-  var d = cache.dump()  // { a: { key: 'a', value: 'A', lu: 0 } }
+  var d = cache.dump()  // { a: { key: "a", value: "A", lu: 0 } }
   t.ok(d.a)
-  t.equal(d.a.key, 'a')
-  t.equal(d.a.value, 'A')
+  t.equal(d.a.key, "a")
+  t.equal(d.a.value, "A")
   t.equal(d.a.lu, 0)
@@ -119,4 +120,4 @@
   t.ok(d.b)
-  t.equal(d.b.key, 'b')
-  t.equal(d.b.value, 'B')
+  t.equal(d.b.key, "b")
+  t.equal(d.b.value, "B")
   t.equal(d.b.lu, 2)
@@ -126,1 +127,54 @@
 })
+
+
+test("basic with weighed length", function (t) {
+  var cache = new LRU(100, function (item) { return item.size } )
+  cache.set("key", {val: "value", size: 50})
+  t.equal(cache.get("key").val, "value")
+  t.equal(cache.get("nada"), undefined)
+  t.equal(cache.lengthCalculator(cache.get("key")), 50)
+  t.equal(cache.length, 50)
+  t.equal(cache.maxLength, 100)
+  t.end()
+})
+
+
+test("weighed length item too large", function (t) {
+  var cache = new LRU(10, function (item) { return item.size } )
+  t.equal(cache.maxLength, 10)
+
+  // should fall out immediately
+  cache.set("key", {val: "value", size: 50})
+
+  t.equal(cache.length, 0)
+  t.equal(cache.get("key"), undefined)
+  t.end()
+})
+
+test("least recently set with weighed length", function (t) {
+  var cache = new LRU(8, function (item) { return item.length })
+  cache.set("a", "A")
+  cache.set("b", "BB")
+  cache.set("c", "CCC")
+  cache.set("d", "DDDD")
+  t.equal(cache.get("d"), "DDDD")
+  t.equal(cache.get("c"), "CCC")
+  t.equal(cache.get("b"), undefined)
+  t.equal(cache.get("a"), undefined)
+  t.end()
+})
+
+test("lru recently gotten with weighed length", function (t) {
+  var cache = new LRU(8, function (item) { return item.length })
+  cache.set("a", "A")
+  cache.set("b", "BB")
+  cache.set("c", "CCC")
+  cache.get("a")
+  cache.get("b")
+  cache.set("d", "DDDD")
+  t.equal(cache.get("c"), undefined)
+  t.equal(cache.get("d"), "DDDD")
+  t.equal(cache.get("b"), "BB")
+  t.equal(cache.get("a"), "A")
+  t.end()
+})

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Improved metrics

Total package byte prevSize

10634

increased by46.64%

Number of package files

7

increased by16.67%

Lines of code

281

increased by41.92%

Number of lines in readme file

27

increased by80%

No dependency changes