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130 lines
3.3 KiB
130 lines
3.3 KiB
/*jshint unused:false*/
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var cache_manager = require('../');
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var memory_cache = cache_manager.caching({store: 'memory', max: 100, ttl: 10/*seconds*/});
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var memory_cache2 = cache_manager.caching({store: 'memory', max: 100, ttl: 100/*seconds*/});
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//
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// Basic usage
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//
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memory_cache.set('foo', 'bar', function (err) {
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if (err) { throw err; }
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memory_cache.get('foo', function (err, result) {
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console.log(result);
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// >> 'bar'
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memory_cache.del('foo', function (err) {
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if (err) {
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console.log(err);
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}
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});
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});
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});
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function get_user(id, cb) {
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setTimeout(function () {
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console.log("Fetching user from slow database.");
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cb(null, {id: id, name: 'Bob'});
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}, 100);
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}
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var user_id = 123;
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var key = 'user_' + user_id;
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//
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// wrap() example
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//
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// Instead of manually managing the cache like this:
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function get_cached_user_manually(id, cb) {
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memory_cache.get(id, function (err, result) {
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if (err) { return cb(err); }
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if (result) {
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return cb(null, result);
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}
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get_user(id, function (err, result) {
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if (err) { return cb(err); }
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memory_cache.set(id, result);
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cb(null, result);
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});
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});
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}
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// ... you can instead use the `wrap` function:
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function get_cached_user(id, cb) {
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memory_cache.wrap(id, function (cache_callback) {
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get_user(id, cache_callback);
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}, cb);
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}
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get_cached_user(user_id, function (err, user) {
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// First time fetches the user from the (fake) database:
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console.log(user);
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get_cached_user(user_id, function (err, user) {
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// Second time fetches from cache.
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console.log(user);
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});
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});
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// Outputs:
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// Returning user from slow database.
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// { id: 123, name: 'Bob' }
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// { id: 123, name: 'Bob' }
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// Same as above, but written differently:
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memory_cache.wrap(key, function (cb) {
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get_user(user_id, cb);
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}, function (err, user) {
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console.log(user);
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// Second time fetches user from memory_cache
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memory_cache.wrap(key, function (cb) {
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get_user(user_id, cb);
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}, function (err, user) {
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console.log(user);
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});
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});
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//
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// multi-cache example
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//
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var multi_cache = cache_manager.multi_caching([memory_cache, memory_cache2]);
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var user_id2 = 456;
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var key2 = 'user_' + user_id;
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multi_cache.wrap(key2, function (cb) {
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get_user(user_id2, cb);
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}, function (err, user) {
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console.log(user);
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// Second time fetches user from memory_cache, since it's highest priority.
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// If the data expires in the memory cache, the next fetch would pull it from
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// the Redis cache, and set the data in memory again.
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multi_cache.wrap(key2, function (cb) {
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get_user(user_id2, cb);
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}, function (err, user) {
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console.log(user);
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});
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// Sets in all caches.
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multi_cache.set('foo2', 'bar2', function (err) {
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if (err) { throw err; }
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// Fetches from highest priority cache that has the key.
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multi_cache.get('foo2', function (err, result) {
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console.log(result);
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// >> 'bar2'
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// Delete from all caches
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multi_cache.del('foo2', function (err) {
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if (err) {
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console.log(err);
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}
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process.exit();
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});
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});
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});
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});
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