cache/README.md

cachemap

cachemap is an in-memory key:value store/cache similar to memcached that is suitable for applications running on a single machine. Its major advantage is that, being essentially a thread-safe map[string]interface{} with expiration times, it doesn't need to serialize or transmit its contents over the network.

Any object can be stored, for a given duration or forever, and the cache can be safely used by multiple goroutines.

Although cachemap isn't meant to be used as a persistent datastore, the entire cache can be saved to and loaded from a file (using c.Items() to retrieve the items map to serialize, and NewFrom() to create a cache from a deserialized one) to recover from downtime quickly. (See the docs for NewFrom() for caveats.)

Installation

go get github.com/ggaaooppeenngg/cachemap

Usage

	import (
		"fmt"
		"github.com/patrickmn/cachemap"
		"time"
	)

	func main() {

		// Create a cache with a default expiration time of 5 minutes, and which
		// purges expired items every 30 seconds
		c := cache.New(5*time.Minute, 30*time.Second)

		// Set the value of the key "foo" to "bar", with the default expiration time
		c.Set("foo", "bar", cache.DefaultExpiration)

		// Set the value of the key "baz" to 42, with no expiration time
		// (the item won't be removed until it is re-set, or removed using
		// c.Delete("baz")
		c.Set("baz", 42, cache.NoExpiration)

		// Get the string associated with the key "foo" from the cache
		foo, found := c.Get("foo")
		if found {
			fmt.Println(foo)
		}

		// Since Go is statically typed, and cache values can be anything, type
		// assertion is needed when values are being passed to functions that don't
		// take arbitrary types, (i.e. interface{}). The simplest way to do this for
		// values which will only be used once--e.g. for passing to another
		// function--is:
		foo, found := c.Get("foo")
		if found {
			MyFunction(foo.(string))
		}

		// This gets tedious if the value is used several times in the same function.
		// You might do either of the following instead:
		if x, found := c.Get("foo"); found {
			foo := x.(string)
			// ...
		}
		// or
		var foo string
		if x, found := c.Get("foo"); found {
			foo = x.(string)
		}
		// ...
		// foo can then be passed around freely as a string

		// Want performance? Store pointers!
		c.Set("foo", &MyStruct, cache.DefaultExpiration)
		if x, found := c.Get("foo"); found {
			foo := x.(*MyStruct)
			// ...
		}

		// If you store a reference type like a pointer, slice, map or channel, you
		// do not need to run Set if you modify the underlying data. The cached
		// reference points to the same memory, so if you modify a struct whose
		// pointer you've stored in the cache, retrieving that pointer with Get will
		// point you to the same data:
		foo := &MyStruct{Num: 1}
		c.Set("foo", foo, cache.DefaultExpiration)
		// ...
		x, _ := c.Get("foo")
		foo := x.(*MyStruct)
		fmt.Println(foo.Num)
		// ...
		foo.Num++
		// ...
		x, _ := c.Get("foo")
		foo := x.(*MyStruct)
		foo.Println(foo.Num)

		// will print:
		// 1
		// 2

	}

Benchmark

benchmark\package	go-cache	cachemap
BenchmarkCacheGetExpiring-v	30000000,46.3 ns/op	20000000,43.4 ns/op
BenchmarkCacheGetNotExpiring-v	50000000,29.6 ns/op	50000000,29.6 ns/op
BenchmarkRWMutexMapGet-x	50000000,26.7 ns/op	50000000,26.6 ns/op
BenchmarkRWMutexInterfaceMapGetStruct-x	20000000,75.1 ns/op	20000000,66.1 ns/op
BenchmarkRWMutexInterfaceMapGetString-x	20000000,75.3 ns/op	20000000,67.6 ns/op
BenchmarkCacheGetConcurrentExpiring-v	20000000,67.8 ns/op	20000000,68.9 ns/op
BenchmarkCacheGetConcurrentNotExpiring-v	20000000,69.2 ns/op	20000000,68.6 ns/op
BenchmarkRWMutexMapGetConcurrent-x	30000000,57.4 ns/op	20000000,64.7 ns/op
BenchmarkCacheGetManyConcurrentExpiring-v	100000000,68.0 ns/op	100000000,66.7 ns/op
BenchmarkCacheGetManyConcurrentNotExpiring-v	2000000000,68.3 ns/op	20000000,69.3 ns/op
BenchmarkCacheSetExpiring-4	10000000,173 ns/op	20000000,91.4 ns/op
BenchmarkCacheSetNotExpiring-4	10000000,123 ns/op	20000000,100 ns/op
BenchmarkRWMutexMapSet-4	20000000,88.5 ns/op	20000000,74.5 ns/op
BenchmarkCacheSetDelete-4	5000000,257 ns/op	10000000,151 ns/op
BenchmarkRWMutexMapSetDelete-4	10000000,180 ns/op	10000000,154 ns/op
BenchmarkCacheSetDeleteSingleLock-4	10000000,211 ns/op	20000000,118 ns/op
BenchmarkRWMutexMapSetDeleteSingleLock-4	10000000,142 ns/op	20000000,118 ns/op
BenchmarkIncrementInt-4	10000000,167 ns/op
BenchmarkDeleteExpiredLoop-4	500,2584384 ns/op	1000,2173019 ns/op
BenchmarkShardedCacheGetExpiring-4	20000000,79.5 ns/op	20000000,67.9 ns/op
BenchmarkShardedCacheGetNotExpiring-4	30000000,59.3 ns/op	20000000,49.9 ns/op
BenchmarkShardedCacheGetManyConcurrentExpiring-4	2000000000,52.4 ns/op	10000000,75.8 ns/op
BenchmarkShardedCacheGetManyConcurrentNotExpiring-4	100000000,68.2 ns/op	20000000,75.8 ns/op