135 lines
6.0 KiB
Markdown
135 lines
6.0 KiB
Markdown
[](https://travis-ci.org/ggaaooppeenngg/cachemap)
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[](https://goreportcard.com/report/github.com/ggaaooppeenngg/cachemap)
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[](https://godoc.org/github.com/ggaaooppeenngg/cachemap)
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# cachemap
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cachemap is an in-memory key:value store/cache similar to memcached that is
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suitable for applications running on a single machine. Its major advantage is
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that, being essentially a thread-safe `map[string]interface{}` with expiration
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times, it doesn't need to serialize or transmit its contents over the network.
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Any object can be stored, for a given duration or forever, and the cache can be
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safely used by multiple goroutines.
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Although cachemap isn't meant to be used as a persistent datastore, the entire
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cache can be saved to and loaded from a file (using `c.Items()` to retrieve the
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items map to serialize, and `NewFrom()` to create a cache from a deserialized
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one) to recover from downtime quickly. (See the docs for `NewFrom()` for caveats.)
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### Installation
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`go get github.com/ggaaooppeenngg/cachemap`
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### Usage
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```go
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import (
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"fmt"
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"github.com/patrickmn/cachemap"
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"time"
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)
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func main() {
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// Create a cache with a default expiration time of 5 minutes, and which
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// purges expired items every 30 seconds
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c := cache.New(5*time.Minute, 30*time.Second)
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// Set the value of the key "foo" to "bar", with the default expiration time
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c.Set("foo", "bar", cache.DefaultExpiration)
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// Set the value of the key "baz" to 42, with no expiration time
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// (the item won't be removed until it is re-set, or removed using
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// c.Delete("baz")
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c.Set("baz", 42, cache.NoExpiration)
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// Get the string associated with the key "foo" from the cache
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foo, found := c.Get("foo")
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if found {
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fmt.Println(foo)
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}
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// Since Go is statically typed, and cache values can be anything, type
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// assertion is needed when values are being passed to functions that don't
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// take arbitrary types, (i.e. interface{}). The simplest way to do this for
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// values which will only be used once--e.g. for passing to another
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// function--is:
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foo, found := c.Get("foo")
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if found {
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MyFunction(foo.(string))
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}
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// This gets tedious if the value is used several times in the same function.
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// You might do either of the following instead:
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if x, found := c.Get("foo"); found {
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foo := x.(string)
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// ...
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}
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// or
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var foo string
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if x, found := c.Get("foo"); found {
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foo = x.(string)
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}
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// ...
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// foo can then be passed around freely as a string
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// Want performance? Store pointers!
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c.Set("foo", &MyStruct, cache.DefaultExpiration)
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if x, found := c.Get("foo"); found {
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foo := x.(*MyStruct)
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// ...
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}
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// If you store a reference type like a pointer, slice, map or channel, you
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// do not need to run Set if you modify the underlying data. The cached
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// reference points to the same memory, so if you modify a struct whose
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// pointer you've stored in the cache, retrieving that pointer with Get will
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// point you to the same data:
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foo := &MyStruct{Num: 1}
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c.Set("foo", foo, cache.DefaultExpiration)
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// ...
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x, _ := c.Get("foo")
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foo := x.(*MyStruct)
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fmt.Println(foo.Num)
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// ...
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foo.Num++
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// ...
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x, _ := c.Get("foo")
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foo := x.(*MyStruct)
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foo.Println(foo.Num)
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// will print:
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// 1
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// 2
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}
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```
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### Benchmark
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| benchmark\package | go-cache | cachemap |
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|-----------------------------------------------------|-----------------------|----------------------|
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| BenchmarkCacheGetExpiring-v | 30000000,46.3 ns/op | 20000000,43.4 ns/op |
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| BenchmarkCacheGetNotExpiring-v | 50000000,29.6 ns/op | 50000000,29.6 ns/op |
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| BenchmarkRWMutexMapGet-x | 50000000,26.7 ns/op | 50000000,26.6 ns/op |
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| BenchmarkRWMutexInterfaceMapGetStruct-x | 20000000,75.1 ns/op | 20000000,66.1 ns/op |
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| BenchmarkRWMutexInterfaceMapGetString-x | 20000000,75.3 ns/op | 20000000,67.6 ns/op |
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| BenchmarkCacheGetConcurrentExpiring-v | 20000000,67.8 ns/op | 20000000,68.9 ns/op |
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| BenchmarkCacheGetConcurrentNotExpiring-v | 20000000,69.2 ns/op | 20000000,68.6 ns/op |
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| BenchmarkRWMutexMapGetConcurrent-x | 30000000,57.4 ns/op | 20000000,64.7 ns/op |
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| BenchmarkCacheGetManyConcurrentExpiring-v | 100000000,68.0 ns/op | 100000000,66.7 ns/op |
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| BenchmarkCacheGetManyConcurrentNotExpiring-v | 2000000000,68.3 ns/op | 20000000,69.3 ns/op |
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| BenchmarkCacheSetExpiring-4 | 10000000,173 ns/op | 20000000,91.4 ns/op |
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| BenchmarkCacheSetNotExpiring-4 | 10000000,123 ns/op | 20000000,100 ns/op |
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| BenchmarkRWMutexMapSet-4 | 20000000,88.5 ns/op | 20000000,74.5 ns/op |
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| BenchmarkCacheSetDelete-4 | 5000000,257 ns/op | 10000000,151 ns/op |
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| BenchmarkRWMutexMapSetDelete-4 | 10000000,180 ns/op | 10000000,154 ns/op |
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| BenchmarkCacheSetDeleteSingleLock-4 | 10000000,211 ns/op | 20000000,118 ns/op |
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| BenchmarkRWMutexMapSetDeleteSingleLock-4 | 10000000,142 ns/op | 20000000,118 ns/op |
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| BenchmarkIncrementInt-4 | 10000000,167 ns/op | |
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| BenchmarkDeleteExpiredLoop-4 | 500,2584384 ns/op | 1000,2173019 ns/op |
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| BenchmarkShardedCacheGetExpiring-4 | 20000000,79.5 ns/op | 20000000,67.9 ns/op |
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| BenchmarkShardedCacheGetNotExpiring-4 | 30000000,59.3 ns/op | 20000000,49.9 ns/op |
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| BenchmarkShardedCacheGetManyConcurrentExpiring-4 | 2000000000,52.4 ns/op | 10000000,75.8 ns/op |
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| BenchmarkShardedCacheGetManyConcurrentNotExpiring-4 | 100000000,68.2 ns/op | 20000000,75.8 ns/op |
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