You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
292 lines
12 KiB
Plaintext
292 lines
12 KiB
Plaintext
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
|
|
|
|
func New(de, ci time.Duration) *Cache
|
|
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 their next lookup or before calling DeleteExpired.
|
|
|
|
func (c *Cache) Set(k string, x interface{}, d time.Duration)
|
|
Add an item to the cache, replacing any existing item. If the duration is
|
|
0, the cache's default expiration time is used. If it is -1, the item never
|
|
expires.
|
|
|
|
func (c *Cache) Add(k string, x interface{}, d time.Duration) error
|
|
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 if not.
|
|
|
|
func (c *Cache) Replace(k string, x interface{}, d time.Duration) error
|
|
Set a new value for the cache key only if it already exists. Returns an
|
|
error if it does not.
|
|
|
|
func (c *Cache) Get(k string) (interface{}, bool)
|
|
Get an item from the cache. Returns the item or nil, and a bool indicating
|
|
whether the key was found.
|
|
|
|
func (c *Cache) Increment(k string, n int64) error
|
|
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 (c *Cache) IncrementFloat(k string, n float64) error
|
|
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.
|
|
|
|
func (c *Cache) IncrementInt(k string, n int) (int, error)
|
|
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 (c *Cache) IncrementInt8(k string, n int8) (int8, error)
|
|
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 (c *Cache) IncrementInt16(k string, n int16) (int16, error)
|
|
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 (c *Cache) IncrementInt32(k string, n int32) (int32, error)
|
|
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 (c *Cache) IncrementInt64(k string, n int64) (int64, error)
|
|
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 (c *Cache) IncrementUint(k string, n uint) (uint, error)
|
|
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 (c *Cache) IncrementUint8(k string, n uint8) (uint8, error)
|
|
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 (c *Cache) IncrementUint16(k string, n uint16) (uint16, error)
|
|
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 (c *Cache) IncrementUint32(k string, n uint32) (uint32, error)
|
|
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 (c *Cache) IncrementUint64(k string, n uint64) (uint64, error)
|
|
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 (c *Cache) IncrementFloat32(k string, n float32) (float32, error)
|
|
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 (c *Cache) IncrementFloat64(k string, n float64) (float64, error)
|
|
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 (c *Cache) Decrement(k string, n int64) error
|
|
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.
|
|
|
|
func (c *Cache) DecrementFloat(k string, n float64) error
|
|
Decrement an item of type float32 or float64 by n. Returns an error if the
|
|
item's value is floating point, if it was not found, or if it is not
|
|
possible to decrement it by n.
|
|
|
|
func (c *Cache) DecrementInt(k string, n int) (int, error)
|
|
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 (c *Cache) DecrementInt8(k string, n int8) (int8, error)
|
|
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 (c *Cache) DecrementInt16(k string, n int16) (int16, error)
|
|
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 (c *Cache) DecrementInt32(k string, n int32) (int32, error)
|
|
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 (c *Cache) DecrementInt64(k string, n int64) (int64, error)
|
|
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 (c *Cache) DecrementUint(k string, n uint) (uint, error)
|
|
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 (c *Cache) DecrementUintptr(k string, n uintptr) (uintptr, error)
|
|
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 (c *Cache) DecrementUint8(k string, n uint8) (uint8, error)
|
|
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 (c *Cache) DecrementUint16(k string, n uint16) (uint16, error)
|
|
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 (c *Cache) DecrementUint32(k string, n uint32) (uint32, error)
|
|
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 (c *Cache) DecrementUint64(k string, n uint64) (uint64, error)
|
|
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 (c *Cache) DecrementFloat32(k string, n float32) (float32, error)
|
|
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 (c *Cache) DecrementFloat64(k string, n float64) (float64, error)
|
|
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 (c *Cache) Delete(k string)
|
|
Delete an item from the cache. Does nothing if the key does not exist in the
|
|
cache.
|
|
|
|
func (c *Cache) DeleteExpired()
|
|
Delete all expired items from the cache.
|
|
|
|
func (c *Cache) Flush()
|
|
Delete all items from the cache.
|
|
|
|
func (c *Cache) Save(w io.Writer) error
|
|
Write the cache's items (using Gob) to an io.Writer. Returns an error if
|
|
the serialization fails, e.g. because there are unserializable objects like
|
|
channels in the cache.
|
|
|
|
func (c *Cache) SaveFile(fname string) error
|
|
Save the cache's items to the given filename, creating the file if it
|
|
doesn't exist, and overwriting it if it does.
|
|
|
|
func (c *Cache) Load(r io.Reader) error
|
|
Add (Gob-serialized) cache items from an io.Reader, excluding any items
|
|
with keys that already exist in the current cache.
|
|
|
|
func (c *Cache) LoadFile(fname string) error
|
|
Loads and adds cache items from the given filename, excluding any items
|
|
with keys that already exist in the current cache.
|