ttl-mem-cache - npm Package Compare versions

Comparing version 1.3.0 to 1.4.0

lib/cache.js

@@ -6,3 +6,3 @@ 'use strict';
 module.exports = class Cache extends stream.Duplex {
-    constructor({ maxAge = 5 * 60 * 1000, stale = false } = {}) {
+    constructor({ maxAge = 5 * 60 * 1000, stale = false, changefeed = false } = {}) {
         super({
@@ -13,2 +13,3 @@ objectMode: true
         this.stale = stale;
+        this.changefeed = changefeed;
         this.store = new Map();
@@ -34,3 +35,3 @@
         }
-        return undefined;
+        return null;
     }
@@ -47,4 +48,17 @@
         const expires = this.constructor._calculateExpire((maxAge || this.maxAge));
+
+        const eventObj = {
+            key,
+            value
+        };
+
+        if (this.changefeed) {
+            eventObj.value = {
+                oldVal: this.get(key),
+                newVal: value
+            };
+        }
+
         this.store.set(key, { value, expires });
-        this.emit('set', { key, value });
+        this.emit('set', eventObj);
         return value;
@@ -51,0 +65,0 @@ }

package.json

 {
   "name": "ttl-mem-cache",
-  "version": "1.3.0",
+  "version": "1.4.0",
   "description": "A in memory time to live cache with streaming support.",
@@ -5,0 +5,0 @@ "main": "lib/cache.js",

README.md

@@ -60,2 +60,3 @@ # ttl-mem-cache
  * stale - `Boolean` - If expired items in cache should be returned when pruned from the cache. Default: `false`.
+ * changelog - `Boolean` - If emitted `set` event and stream should contain both old and new value. Default: `false`
 
@@ -70,3 +71,3 @@ If an option Object with a `maxAge` is not provided all items in the cache will by
 for retrieving items from the cache. By default pruning happens before the method
-returns a value so if an item have expired, `undefined` will be returned for expired
+returns a value so if an item have expired, `null` will be returned for expired
 items. By setting `stale` to `true`, these methods will return the pruned item(s)
@@ -117,4 +118,4 @@ before they are removed from the cache.
 the max age set on it, the item will be removed from the cache and this method
-will return `undefined` unless `stale` is set to `true` on the constructor. Then
-the expired item will be returned before its removed from the cache.
+will return `null` unless `stale` is set to `true` on the constructor. Then the
+expired item will be returned before its removed from the cache.
 
@@ -213,2 +214,5 @@
 
+If `changefeed` is set to be `true` on the constructor, the emitted Object will hold both
+old and new value for the key. See "changelog" for further info.
+
 ### dispose
@@ -316,4 +320,43 @@
 
+If `changefeed` is set to be `true` on the constructor, the emitted Object in the Readable stream
+will hold both old and new value for the key. See "changelog" for further info.
 
 
+
+## Changelog
+
+If the attribute `changelog` is set to `true` on the constructor, some emitted events will
+emit an object holding both old and new values for the key.
+
+The emitted object looks like this:
+
+```js
+{
+    key: 'a',
+    value: {
+        oldVal: 'foo',
+        newVal: 'bar'
+    }
+}
+```
+
+Example:
+
+```js
+const Cache = require('ttl-mem-cache');
+
+const cache = new Cache({ changefeed: true });
+cache.on('set', (item) => {
+    // item will be in the format above
+});
+cache.set('a', 'foo');
+cache.set('a', 'bar');
+```
+
+If a key does not hold a value in cache before, `oldVal` will be `null`.
+If a key hold a value which has expired and `stale` is `false`, `oldVal` will be `null`.
+If a key hold a value which has expired and `stale` is `true`, `oldVal` will be the old value.
+
+
+
 ## node.js compabillity
@@ -320,0 +363,0 @@

New alerts

Major refactor

Supply chain risk

Package has recently undergone a major refactor. It may be unstable or indicate significant internal changes. Use caution when updating to versions that include significant changes.

Found 1 instance in 1 package

Improved metrics

Total package byte prevSize

44977

65.81%

Number of package files

9

12.5%

Lines of code

700

291.06%

Number of lines in readme file

398

12.11%

Worsened metrics

Number of medium supply chain risk alerts

1

Infinity%

No dependency changes