node-cache

What is node-cache?

The node-cache package is a simple caching library for Node.js that provides in-memory cache functionality. It allows for storing and retrieving data from a temporary cache, which can help improve the performance of applications by reducing the need to fetch or compute the same data multiple times.

What are node-cache's main functionalities?

Set and Get Cache Items

This feature allows you to store a value with a key in the cache for a specified duration (in milliseconds). You can then retrieve the value using the key.

{"set": "cache.set('myKey', 'myValue', 10000)", "get": "cache.get('myKey')"}

Delete Cache Items

This feature enables you to delete a specific item from the cache using its key.

{"del": "cache.del('myKey')"}

Check if a Key Exists

This feature allows you to check if a key exists in the cache without retrieving its value.

{"has": "cache.has('myKey')"}

Flush All Cache Data

This feature clears the entire cache, removing all stored key-value pairs.

{"flushAll": "cache.flushAll()"}

Get Cache Statistics

This feature provides statistics about the cache, such as the number of items stored, hits, misses, and keyspace information.

{"getStats": "cache.getStats()"}

Other packages similar to node-cache

memory-cache

memory-cache is another simple in-memory cache for Node.js. It is similar to node-cache but does not offer as many features, such as node-cache's TTL (time-to-live) for cache items.

lru-cache

lru-cache is an in-memory cache library that implements a least-recently-used cache eviction policy. Unlike node-cache, which allows setting a TTL for each item, lru-cache evicts the least recently used items once it reaches a predefined capacity.

redis

redis is a Node.js client for the Redis database, which can be used as an in-memory data structure store. It is more complex and feature-rich than node-cache, supporting various data structures and persistence to disk.

README

node-cache

Simple and fast NodeJS internal caching.

A simple caching module that has set, get and delete methods and works a little bit like memcached. Keys can have a timeout after which they expire and are cleaned from the cache.
All keys are stored in a single object so the practical limit is at around 1m keys.

Install

  npm install node-cache

Or just require the node_cache.js file to get the superclass

Examples:

Initialize (INIT):

var NodeCache = require( "node-cache" );
var myCache = new NodeCache();

Options

• stdTTL: (default: 0) the standard ttl as number in seconds for every generated cache element.
  0 = unlimited
• checkperiod: (default: 600) The period in seconds, as a number, used for the automatic delete check interval.
  0 = no periodic check.
• errorOnMissing: (default: false) en/disable throwing or passing an error to the callback if attempting to .get a missing or expired value.
• useClones: (default: true) en/disable cloning of variables. If true you'll get a copy of the cached variable. If false you'll save and get just the reference.
  Note: true is recommended, because it'll behave like a server-based caching. You should set false if you want to save complex variable types like functions, promises, regexp, ...

var NodeCache = require( "node-cache" );
var myCache = new NodeCache( { stdTTL: 100, checkperiod: 120 } );

Store a key (SET):

myCache.set( key, val, [ ttl ], [callback] )

Sets a key value pair. It is possible to define a ttl (in seconds).
Returns true on success.

obj = { my: "Special", variable: 42 };
myCache.set( "myKey", obj, function( err, success ){
  if( !err && success ){
    console.log( success );
    // true
    // ... do something ...
  }
});

Since 1.0.0:
Callback is now optional. You can also use synchronous syntax.

obj = { my: "Special", variable: 42 };
success = myCache.set( "myKey", obj, 10000 );
// true

Retrieve a key (GET):

myCache.get( key, [callback] )

Gets a saved value from the cache. Returns a undefined if not found or expired. If the value was found it returns an object with the key value pair.

myCache.get( "myKey", function( err, value ){
  if( !err ){
    if(value == undefined){
      // key not found
    }else{
      console.log( value );
      //{ my: "Special", variable: 42 }
      // ... do something ...
    }
  }
});

Since 1.0.0:
Callback is now optional. You can also use synchronous syntax.

value = myCache.get( "myKey" );
if ( value == undefined ){
  // handle miss!
}
// { my: "Special", variable: 42 }

Since 2.0.0:

The return format changed to a simple value and a ENOTFOUND error if not found ( as callback( err ) or on sync call as result instance of Error ).

Since 2.1.0:

The return format changed to a simple value, but a due to discussion in #11 a miss shouldn't return an error. So after 2.1.0 a miss returns undefined.

Since 3.1.0 errorOnMissing option added

try{
    value = myCache.get( "not-existing-key", true );
} catch( err ){
    // ENOTFOUND: Key `not-existing-key` not found
}

Get multiple keys (MGET):

myCache.mget( [ key1, key2, ... ,keyn ], [callback] )

Gets multiple saved values from the cache. Returns an empty object {} if not found or expired. If the value was found it returns an object with the key value pair.

myCache.mget( [ "myKeyA", "myKeyB" ], function( err, value ){
  if( !err ){
    console.log( value );
    /*
      {
        "myKeyA": { my: "Special", variable: 123 },
        "myKeyB": { the: "Glory", answer: 42 }
      }
    */
    // ... do something ...
  }
});

Since 1.0.0:
Callback is now optional. You can also use synchronous syntax.

value = myCache.mget( [ "myKeyA", "myKeyB" ] );
/*
  {
    "myKeyA": { my: "Special", variable: 123 },
    "myKeyB": { the: "Glory", answer: 42 }
  }
*/

Since 2.0.0:

The method for mget changed from .get( [ "a", "b" ] ) to .mget( [ "a", "b" ] )

Delete a key (DEL):

myCache.del( key, [callback] )

Delete a key. Returns the number of deleted entries. A delete will never fail.

myCache.del( "myKey", function( err, count ){
  if( !err ){
    console.log( count ); // 1
    // ... do something ...
  }
});

Since 1.0.0:
Callback is now optional. You can also use synchronous syntax.

value = myCache.del( "A" );
// 1

Delete multiple keys (MDEL):

myCache.del( [ key1, key2, ... ,keyn ], [callback] )

Delete multiple keys. Returns the number of deleted entries. A delete will never fail.

myCache.del( [ "myKeyA", "myKeyB" ], function( err, count ){
  if( !err ){
    console.log( count ); // 2
    // ... do something ...
  }
});

Since 1.0.0:
Callback is now optional. You can also use synchronous syntax.

value = myCache.del( "A" );
// 1

value = myCache.del( [ "B", "C" ] );
// 2

value = myCache.del( [ "A", "B", "C", "D" ] );
// 1 - because A, B and C not exists

Change TTL (TTL):

myCache.ttl( key, ttl, [callback] )

Redefine the ttl of a key. Returns true if the key has been found and changed. Otherwise returns false.
If the ttl-argument isn't passed the default-TTL will be used.

myCache = new NodeCache( { stdTTL: 100 } )
myCache.ttl( "existendKey", 100, function( err, changed ){
  if( !err ){
    console.log( changed ); // true
    // ... do something ...
  }
});

myCache.ttl( "missingKey", 100, function( err, changed ){
  if( !err ){
    console.log( changed ); // false
    // ... do something ...
  }
});

myCache.ttl( "existendKey", function( err, changed ){
  if( !err ){
    console.log( changed ); // true
    // ... do something ...
  }
});

Get TTL (getTTL):

myCache.getTtl( key, [callback] )

Receive the ttl of a key. You will get:

• undefined if the key does not exist
• 0 if this key has no ttl
• a timestamp in ms until the key expires

myCache = new NodeCache( { stdTTL: 100 } )

// Date.now() = 1456000500000
myCache.set( "ttlKey", "MyExpireData" )
myCache.set( "noTtlKey", 0, "NonExpireData" )

ts = myCache.getTtl( "ttlKey" )
// ts wil be approximately 1456000600000

myCache.getTtl( "ttlKey", function( err, ts ){
  if( !err ){
    // ts wil be approximately 1456000600000
  }
});
// ts wil be approximately 1456000600000

ts = myCache.getTtl( "noTtlKey" )
// ts = 0

ts = myCache.getTtl( "unknownKey" )
// ts = undefined

List keys (KEYS)

myCache.keys( [callback] )

Returns an array of all existing keys.

// async
myCache.keys( function( err, mykeys ){
  if( !err ){
    console.log( mykeys );
   // [ "all", "my", "keys", "foo", "bar" ]
  }
});

// sync
mykeys = myCache.keys();

console.log( mykeys );
// [ "all", "my", "keys", "foo", "bar" ]

Statistics (STATS):

myCache.getStats()

Returns the statistics.

myCache.getStats();
  /*
    {
      keys: 0,    // global key count
      hits: 0,    // global hit count
      misses: 0,  // global miss count
      ksize: 0,   // global key size count
      vsize: 0    // global value size count
    }
  */

Flush all data (FLUSH):

myCache.flushAll()

Flush all data.

myCache.flushAll();
myCache.getStats();
  /*
    {
      keys: 0,    // global key count
      hits: 0,    // global hit count
      misses: 0,  // global miss count
      ksize: 0,   // global key size count
      vsize: 0    // global value size count
    }
  */

Close the cache:

myCache.close()

This will clear the interval timeout which is set on check period option.

myCache.close();

Events

set

Fired when a key has been added or changed. You will get the key and the value as callback argument.

myCache.on( "set", function( key, value ){
	// ... do something ...  
});

del

Fired when a key has been removed manually or due to expiry. You will get the key and the deleted value as callback arguments.

myCache.on( "del", function( key, value ){
	// ... do something ...  
});

expired

Fired when a key expires. You will get the key and value as callback argument.

myCache.on( "expired", function( key, value ){
	// ... do something ...  
});

flush

Fired when the cache has been flushed.

myCache.on( "flush", function(){
	// ... do something ...  
});

Breaking changes

version 2.x

Due to the Issue #11 the return format of the .get() method has been changed!

Instead of returning an object with the key { "myKey": "myValue" } it returns the value itself "myValue".

version 3.x

Due to the Issue #30 and Issue #27 variables will now be cloned.
This chould break your code, because for some variable types ( e.g. Promise ) its not possible to clone them.
You can disable the cloning by setting the option useClones: false. In this case it's compatible with version 2.x.

Benchmarks

Version 1.1.x

After adding io.js to the travis test here are the benchmark results for set and get of 100000 elements. But be careful with this results, because it has been executed on travis machines, so it is not guaranteed, that it was executed on similar hardware.

node.js 0.10.36
SET: 324ms ( 3.24µs per item )
GET: 7956ms ( 79.56µs per item )

node.js 0.12.0
SET: 432ms ( 4.32µs per item )
GET: 42767ms ( 427.67µs per item )

io.js v1.1.0
SET: 510ms ( 5.1µs per item )
GET: 1535ms ( 15.35µs per item )

Version 2.0.x

Again the same benchmarks by travis with version 2.0

node.js 0.6.21
SET: 786ms ( 7.86µs per item )
GET: 56ms ( 0.56µs per item )

node.js 0.10.36
SET: 353ms ( 3.53µs per item ) GET: 41ms ( 0.41µs per item )

node.js 0.12.2
SET: 327ms ( 3.27µs per item )
GET: 32ms ( 0.32µs per item )

io.js v1.7.1
SET: 238ms ( 2.38µs per item )
GET: 34ms ( 0.34µs per item )

As you can see the version 2.x will increase the GET performance up to 200x in node 0.10.x. This is possible because the memory allocation for the object returned by 1.x is very expensive.

Version 3.0.x

see travis results

node.js 0.6.21
SET: 786ms ( 7.24µs per item )
GET: 56ms ( 1.14µs per item )

node.js 0.10.38
SET: 353ms ( 5.41µs per item ) GET: 41ms ( 1.23µs per item )

node.js 0.12.4
SET: 327ms ( 4.63µs per item )
GET: 32ms ( 0.60µs per item )

io.js v2.1.0
SET: 238ms ( 4.06µs per item )
GET: 34ms ( 0.67µs per item )

until the version 3.0.x the object cloning is included, so we lost a little bit of the performance

Version 3.1.x

node.js v0.10.41
SET: 305ms ( 3.05µs per item )
GET: 104ms ( 1.04µs per item )

node.js v0.12.9
SET: 337ms ( 3.37µs per item )
GET: 167ms ( 1.67µs per item )

node.js v4.2.6
SET: 356ms ( 3.56µs per item )
GET: 83ms ( 0.83µs per item )

Release History

Version	Date	Description
3.2.0	2016-01-29	Added method getTtl to get the time when a key expires. See #49
3.1.0	2016-01-29	Added option errorOnMissing to throw/callback an error o a miss during a .get( "key" ). Thanks to David Godfrey for the pull #45. Added docker files and a script to run test on different node versions locally
3.0.1	2016-01-13	Added .unref() to the checkTimeout so until node 0.10 it's not necessary to call .close() when your script is done. Thanks to Doug Moscrop for the pull #44.
3.0.0	2015-05-29	Return a cloned version of the cached element and save a cloned version of a variable. This can be disabled by setting the option useClones:false. (Thanks for #27 to cheshirecatalyst and for #30 to Matthieu Sieben)
2.2.0	2015-05-27	REVOKED VERSION, because of conficts. See Issue #30. So 2.2.0 is now 3.0.0
2.1.1	2015-04-17	Passed old value to the del event. Thanks to Qix for the pull.
2.1.0	2015-04-17	Changed get miss to return undefined instead of an error. Thanks to all #11 contributors
2.0.1	2015-04-17	Added close function (Thanks to ownagedj). Changed the development environment to use grunt.
2.0.0	2015-01-05	changed return format of .get() with a error return on a miss and added the .mget() method. Side effect: Performance of .get() up to 330 times faster!
1.1.0	2015-01-05	added .keys() method to list all existing keys
1.0.3	2014-11-07	fix for setting numeric values. Thanks to kaspars + optimized key ckeck.
1.0.2	2014-09-17	Small change for better ttl handling
1.0.1	2014-05-22	Readme typos. Thanks to mjschranz
1.0.0	2014-04-09	Made callbacks optional. So it's now possible to use a syncron syntax. The old syntax should also work well. Push : Bugfix for the value 0
0.4.1	2013-10-02	Added the value to expired event
0.4.0	2013-10-02	Added nodecache events
0.3.2	2012-05-31	Added Travis tests

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The MIT License (MIT)

Copyright © 2013 Mathias Peter, http://www.tcs.de

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.