內存緩存memory-cache

memory-cache 

A simple in-memory cache for node.js

 

Installation

npm install memory-cache --save

 

Usage

var cache = require('memory-cache');
 
// now just use the cache 
 
cache.put('foo', 'bar');
console.log(cache.get('foo'));
 
// that wasn't too interesting, here's the good part 
 
cache.put('houdini', 'disappear', 100, function(key, value) {
    console.log(key + ' did ' + value);
}); // Time in ms 
 
console.log('Houdini will now ' + cache.get('houdini'));
 
setTimeout(function() {
    console.log('Houdini is ' + cache.get('houdini'));
}, 200);
 
 
// create new cache instance 
var newCache = new cache.Cache();
 
newCache.put('foo', 'newbaz');
 
setTimeout(function() {
  console.log('foo in old cache is ' + cache.get('foo'));
  console.log('foo in new cache is ' + newCache.get('foo'));
}, 200);

 

which should print

bar
Houdini will now disappear
houdini did disappear
Houdini is null
foo in old cache is baz
foo in new cache is newbaz

 

API

put = function(key, value, time, timeoutCallback)

• Simply stores a value
• If time isn't passed in, it is stored forever
• Will actually remove the value in the specified time in ms (via setTimeout)
• timeoutCallback is optional function fired after entry has expired with key and value passed (function(key, value) {})
• Returns the cached value

get = function(key)

• Retrieves a value for a given key
• If value isn't cached, returns null

del = function(key)

• Deletes a key, returns a boolean specifying whether or not the key was deleted

clear = function()

• Deletes all keys

size = function()

• Returns the current number of entries in the cache

memsize = function()

• Returns the number of entries taking up space in the cache
• Will usually == size() unless a setTimeout removal went wrong

debug = function(bool)

• Turns on or off debugging

hits = function()

• Returns the number of cache hits (only monitored in debug mode)

misses = function()

• Returns the number of cache misses (only monitored in debug mode)

keys = function()

• Returns all the cache keys

exportJson = function()

• Returns a JSON string representing all the cache data
• Any timeoutCallbacks will be ignored

importJson = function(json: string, options: { skipDuplicates: boolean })

• Merges all the data from a previous call to export into the cache
• Any existing entries before an import will remain in the cache
• Any duplicate keys will be overwritten, unless skipDuplicates is true
• Any entries that would have expired since being exported will expire upon being imported (but their callbacks will not be invoked)
• Available options:
  • skipDuplicates: If true, any duplicate keys will be ignored when importing them. Defaults to false.
• Returns the new size of the cache

Cache = function()

• Cache constructor
• note that require('cache') would return the default instance of Cache
• while require('cache').Cache is the actual class