README
¶
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 may be saved to and loaded from a file (or any io.Reader/Writer) to
recover from downtime quickly.
== Installation
go get github.com/pmylund/go-cache
== Usage
import "github.com/pmylund/go-cache"
// 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", 0)
// 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, -1)
// 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, 0)
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, 0)
...
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
`go doc` or http://godoc.org/github.com/pmylund/go-cache
Documentation
¶
Index ¶
- type Cache
- func (c Cache) Add(k string, x interface{}, d time.Duration) error
- func (c Cache) Decrement(k string, n int64) error
- func (c Cache) DecrementFloat(k string, n float64) error
- func (c Cache) DecrementFloat32(k string, n float32) (float32, error)
- func (c Cache) DecrementFloat64(k string, n float64) (float64, error)
- func (c Cache) DecrementInt(k string, n int) (int, error)
- func (c Cache) DecrementInt16(k string, n int16) (int16, error)
- func (c Cache) DecrementInt32(k string, n int32) (int32, error)
- func (c Cache) DecrementInt64(k string, n int64) (int64, error)
- func (c Cache) DecrementInt8(k string, n int8) (int8, error)
- func (c Cache) DecrementUint(k string, n uint) (uint, error)
- func (c Cache) DecrementUint16(k string, n uint16) (uint16, error)
- func (c Cache) DecrementUint32(k string, n uint32) (uint32, error)
- func (c Cache) DecrementUint64(k string, n uint64) (uint64, error)
- func (c Cache) DecrementUint8(k string, n uint8) (uint8, error)
- func (c Cache) DecrementUintptr(k string, n uintptr) (uintptr, error)
- func (c Cache) Delete(k string)
- func (c Cache) DeleteExpired()
- func (c Cache) Flush()
- func (c Cache) Get(k string) (interface{}, bool)
- func (c Cache) Increment(k string, n int64) error
- func (c Cache) IncrementFloat(k string, n float64) error
- func (c Cache) IncrementFloat32(k string, n float32) (float32, error)
- func (c Cache) IncrementFloat64(k string, n float64) (float64, error)
- func (c Cache) IncrementInt(k string, n int) (int, error)
- func (c Cache) IncrementInt16(k string, n int16) (int16, error)
- func (c Cache) IncrementInt32(k string, n int32) (int32, error)
- func (c Cache) IncrementInt64(k string, n int64) (int64, error)
- func (c Cache) IncrementInt8(k string, n int8) (int8, error)
- func (c Cache) IncrementUint(k string, n uint) (uint, error)
- func (c Cache) IncrementUint16(k string, n uint16) (uint16, error)
- func (c Cache) IncrementUint32(k string, n uint32) (uint32, error)
- func (c Cache) IncrementUint64(k string, n uint64) (uint64, error)
- func (c Cache) IncrementUint8(k string, n uint8) (uint8, error)
- func (c Cache) IncrementUintptr(k string, n uintptr) (uintptr, error)
- func (c Cache) ItemCount() int
- func (c Cache) Items() map[string]*Item
- func (c Cache) Load(r io.Reader) error
- func (c Cache) LoadFile(fname string) error
- func (c Cache) Replace(k string, x interface{}, d time.Duration) error
- func (c Cache) Save(w io.Writer) (err error)
- func (c Cache) SaveFile(fname string) error
- func (c Cache) Set(k string, x interface{}, d time.Duration)
- type Item
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Cache ¶
type Cache struct {
// contains filtered or unexported fields
}
func New ¶
Return a new cache with a given default expiration duration and cleanup interval. If the expiration duration is less than 1, the items in the cache never expire (by default), and must be deleted manually. If the cleanup interval is less than one, expired items are not deleted from the cache before calling DeleteExpired.
func (Cache) Add ¶
Add an item to the cache only if an item doesn't already exist for the given key, or if the existing item has expired. Returns an error otherwise.
func (Cache) Decrement ¶
Decrement an item of type int, int8, int16, int32, int64, uintptr, uint, uint8, uint32, or uint64, float32 or float64 by n. Returns an error if the item's value is not an integer, if it was not found, or if it is not possible to decrement it by n. To retrieve the decremented value, use one of the specialized methods, e.g. DecrementInt64.
func (Cache) DecrementFloat ¶
Decrement an item of type float32 or float64 by n. Returns an error if the item's value is not floating point, if it was not found, or if it is not possible to decrement it by n. Pass a negative number to decrement the value. To retrieve the decremented value, use one of the specialized methods, e.g. DecrementFloat64.
func (Cache) DecrementFloat32 ¶
Decrement an item of type float32 by n. Returns an error if the item's value is not an float32, or if it was not found. If there is no error, the decremented value is returned.
func (Cache) DecrementFloat64 ¶
Decrement an item of type float64 by n. Returns an error if the item's value is not an float64, or if it was not found. If there is no error, the decremented value is returned.
func (Cache) DecrementInt ¶
Decrement an item of type int by n. Returns an error if the item's value is not an int, or if it was not found. If there is no error, the decremented value is returned.
func (Cache) DecrementInt16 ¶
Decrement an item of type int16 by n. Returns an error if the item's value is not an int16, or if it was not found. If there is no error, the decremented value is returned.
func (Cache) DecrementInt32 ¶
Decrement an item of type int32 by n. Returns an error if the item's value is not an int32, or if it was not found. If there is no error, the decremented value is returned.
func (Cache) DecrementInt64 ¶
Decrement an item of type int64 by n. Returns an error if the item's value is not an int64, or if it was not found. If there is no error, the decremented value is returned.
func (Cache) DecrementInt8 ¶
Decrement an item of type int8 by n. Returns an error if the item's value is not an int8, or if it was not found. If there is no error, the decremented value is returned.
func (Cache) DecrementUint ¶
Decrement an item of type uint by n. Returns an error if the item's value is not an uint, or if it was not found. If there is no error, the decremented value is returned.
func (Cache) DecrementUint16 ¶
Decrement an item of type uint16 by n. Returns an error if the item's value is not an uint16, or if it was not found. If there is no error, the decremented value is returned.
func (Cache) DecrementUint32 ¶
Decrement an item of type uint32 by n. Returns an error if the item's value is not an uint32, or if it was not found. If there is no error, the decremented value is returned.
func (Cache) DecrementUint64 ¶
Decrement an item of type uint64 by n. Returns an error if the item's value is not an uint64, or if it was not found. If there is no error, the decremented value is returned.
func (Cache) DecrementUint8 ¶
Decrement an item of type uint8 by n. Returns an error if the item's value is not an uint8, or if it was not found. If there is no error, the decremented value is returned.
func (Cache) DecrementUintptr ¶
Decrement an item of type uintptr by n. Returns an error if the item's value is not an uintptr, or if it was not found. If there is no error, the decremented value is returned.
func (Cache) Delete ¶
func (c Cache) Delete(k string)
Delete an item from the cache. Does nothing if the key is not in the cache.
func (Cache) DeleteExpired ¶
func (c Cache) DeleteExpired()
Delete all expired items from the cache.
func (Cache) Get ¶
Get an item from the cache. Returns the item or nil, and a bool indicating whether the key was found.
func (Cache) Increment ¶
Increment an item of type int, int8, int16, int32, int64, uintptr, uint, uint8, uint32, or uint64, float32 or float64 by n. Returns an error if the item's value is not an integer, if it was not found, or if it is not possible to increment it by n. To retrieve the incremented value, use one of the specialized methods, e.g. IncrementInt64.
func (Cache) IncrementFloat ¶
Increment an item of type float32 or float64 by n. Returns an error if the item's value is not floating point, if it was not found, or if it is not possible to increment it by n. Pass a negative number to decrement the value. To retrieve the incremented value, use one of the specialized methods, e.g. IncrementFloat64.
func (Cache) IncrementFloat32 ¶
Increment an item of type float32 by n. Returns an error if the item's value is not an float32, or if it was not found. If there is no error, the incremented value is returned.
func (Cache) IncrementFloat64 ¶
Increment an item of type float64 by n. Returns an error if the item's value is not an float64, or if it was not found. If there is no error, the incremented value is returned.
func (Cache) IncrementInt ¶
Increment an item of type int by n. Returns an error if the item's value is not an int, or if it was not found. If there is no error, the incremented value is returned.
func (Cache) IncrementInt16 ¶
Increment an item of type int16 by n. Returns an error if the item's value is not an int16, or if it was not found. If there is no error, the incremented value is returned.
func (Cache) IncrementInt32 ¶
Increment an item of type int32 by n. Returns an error if the item's value is not an int32, or if it was not found. If there is no error, the incremented value is returned.
func (Cache) IncrementInt64 ¶
Increment an item of type int64 by n. Returns an error if the item's value is not an int64, or if it was not found. If there is no error, the incremented value is returned.
func (Cache) IncrementInt8 ¶
Increment an item of type int8 by n. Returns an error if the item's value is not an int8, or if it was not found. If there is no error, the incremented value is returned.
func (Cache) IncrementUint ¶
Increment an item of type uint by n. Returns an error if the item's value is not an uint, or if it was not found. If there is no error, the incremented value is returned.
func (Cache) IncrementUint16 ¶
Increment an item of type uint16 by n. Returns an error if the item's value is not an uint16, or if it was not found. If there is no error, the incremented value is returned.
func (Cache) IncrementUint32 ¶
Increment an item of type uint32 by n. Returns an error if the item's value is not an uint32, or if it was not found. If there is no error, the incremented value is returned.
func (Cache) IncrementUint64 ¶
Increment an item of type uint64 by n. Returns an error if the item's value is not an uint64, or if it was not found. If there is no error, the incremented value is returned.
func (Cache) IncrementUint8 ¶
Increment an item of type uint8 by n. Returns an error if the item's value is not an uint8, or if it was not found. If there is no error, the incremented value is returned.
func (Cache) IncrementUintptr ¶
Increment an item of type uintptr by n. Returns an error if the item's value is not an uintptr, or if it was not found. If there is no error, the incremented value is returned.
func (Cache) ItemCount ¶
func (c Cache) ItemCount() int
Returns the number of items in the cache. This may include items that have expired, but have not yet been cleaned up. Equivalent to len(c.Items()).
func (Cache) Items ¶
Returns the items in the cache. This may include items that have expired, but have not yet been cleaned up. If this is significant, the Expiration fields of the items should be checked. Note that explicit synchronization is needed to use a cache and its corresponding Items() return value at the same time, as the map is shared.
func (Cache) Load ¶
Add (Gob-serialized) cache items from an io.Reader, excluding any items with keys that already exist (and haven't expired) in the current cache.
func (Cache) LoadFile ¶
Load and add cache items from the given filename, excluding any items with keys that already exist in the current cache.
func (Cache) Replace ¶
Set a new value for the cache key only if it already exists, and the existing item hasn't expired. Returns an error otherwise.
Source Files