136 lines
5.7 KiB
Markdown
136 lines
5.7 KiB
Markdown
# go-cache
|
|
|
|
go-cache 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 go-cache 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/patrickmn/go-cache`
|
|
|
|
### Usage
|
|
|
|
```go
|
|
import (
|
|
"fmt"
|
|
"github.com/patrickmn/go-cache"
|
|
"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
|
|
|
|
}
|
|
```
|
|
|
|
### Reference
|
|
|
|
`godoc` or [http://godoc.org/github.com/patrickmn/go-cache](http://godoc.org/github.com/patrickmn/go-cache)
|
|
|
|
### 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 |
|