Documentation
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Overview ¶
Package lru implements a least recently used in-memory cache. It used a doubly linked list and purges items if the number of items in the cache exceeds the max, the total size of the cache in memory exceeds the given size, or the item expires.
Index ¶
- Constants
- Variables
- type LRU
- func (c *LRU) Add(key string, value interface{}, exp time.Duration) error
- func (c *LRU) Append(key string, value interface{}) error
- func (c *LRU) CompareAndSwap(key string, value interface{}, exp time.Duration, cas uint64) (err error)
- func (c *LRU) Decrement(key string, delta uint64) (uint64, error)
- func (c *LRU) Del(key string) (err error)
- func (c *LRU) Exists(key string) (exists bool)
- func (c *LRU) Get(key string, dstVal interface{}) (err error)
- func (c *LRU) GetItem(key string, dstVal interface{}) (cas uint64, err error)
- func (c *LRU) Increment(key string, delta uint64) (uint64, error)
- func (c *LRU) Len() int
- func (c *LRU) Prepend(key string, value interface{}) error
- func (c *LRU) Replace(key string, value interface{}) error
- func (c *LRU) Set(key string, value interface{}, exp time.Duration) (err error)
- func (c *LRU) SetItem(key string, value interface{}, exp time.Duration, cas uint64) (err error)
- func (c *LRU) Touch(key string, exp time.Duration) error
- type ShardedLRU
- func (c *ShardedLRU) Add(key string, value interface{}, exp time.Duration) (err error)
- func (c *ShardedLRU) Append(key string, value interface{}) (err error)
- func (c *ShardedLRU) CompareAndSwap(key string, value interface{}, exp time.Duration, cas uint64) (err error)
- func (c *ShardedLRU) Decrement(key string, delta uint64) (uint64, error)
- func (c *ShardedLRU) Del(key string) (err error)
- func (c *ShardedLRU) Exists(key string) bool
- func (c *ShardedLRU) Get(key string, dstVal interface{}) (err error)
- func (c *ShardedLRU) GetItem(key string, dstVal interface{}) (cas uint64, err error)
- func (c *ShardedLRU) Increment(key string, delta uint64) (uint64, error)
- func (c *ShardedLRU) Prepend(key string, value interface{}) (err error)
- func (c *ShardedLRU) Replace(key string, value interface{}) (err error)
- func (c *ShardedLRU) Set(key string, value interface{}, exp time.Duration) (err error)
- func (c *ShardedLRU) SetItem(key string, value interface{}, exp time.Duration, cas uint64) (err error)
- func (c *ShardedLRU) Touch(key string, exp time.Duration) (err error)
Constants ¶
const ( Byte uint64 = 1 Kilobyte = Byte << 10 Megabyte = Kilobyte << 10 Gigabyte = Megabyte << 10 Terabyte = Gigabyte << 10 )
Sizes and defaults for the cache
Variables ¶
var ( // ErrCannotSetValue is returned when an previously set cache value pointer cannot be set. ErrCannotSetValue = errors.New("cannot set value of interface") // ErrCannotAssignValue is returned when a previously set cache value pointer cannot be // updated because the new value's type cannot be assigned to the previous value's type. ErrCannotAssignValue = errors.New("cannot assign value") )
Functions ¶
This section is empty.
Types ¶
type LRU ¶
type LRU struct {
// MaxEntries are the max number of cache entries. 0 is unlimited
MaxEntries int
// MaxSize is the max size, in bytes, of the total cache store in memory
MaxSize uint64
sync.RWMutex
// contains filtered or unexported fields
}
LRU is a least recently used in-memory cache implementation
func (*LRU) Append ¶
Append appends the value to the current key value. The value to append must be a string, []byte or pointer to one of those types.
func (*LRU) CompareAndSwap ¶
func (c *LRU) CompareAndSwap(key string, value interface{}, exp time.Duration, cas uint64) (err error)
CompareAndSwap writes the given item that was previously returned by Get, if the value was neither modified or evicted between the Get and the CompareAndSwap calls. The item's Key should not change between calls but all other item fields may differ. ErrCASConflict is returned if the value
was modified in between the calls. ErrNotStored is returned if the value
was evicted in between the calls.
func (*LRU) Decrement ¶
Decrement decreases the key's value by delta. The expiration remains the same. The underlying value to increment must be a uint64 or pointer to a uint64.
func (*LRU) Get ¶
Get fetches the key into the dstVal. It returns an error if the value doesn't exist.
func (*LRU) Increment ¶
Increment increases the key's value by delta. The exipration remains the same. The existing value must be a uint64 or a pointer to a uint64
func (*LRU) Prepend ¶
Prepend prepends the value to the current key value. The value to prepend must be a string, []byte or pointer to one of those types.
func (*LRU) Replace ¶
Replace replaces the current value for the key with the new value, but only if the key already exists. The expiration remains the same.
type ShardedLRU ¶
type ShardedLRU struct {
// contains filtered or unexported fields
}
ShardedLRU is a LRU with keys split across shards for better performance
func New ¶
func New() *ShardedLRU
New returns a new ShardedLRU with a up to a max of one Gigabyte of memory usage
func NewSharded ¶
func NewSharded(maxSize uint64, maxEntries uint64, shardCt uint64) *ShardedLRU
NewSharded returns a new sharded LRU cache with a maximum in-memory size of maxSize, and total maxEntries spread over shardCt
func (*ShardedLRU) Add ¶
func (c *ShardedLRU) Add(key string, value interface{}, exp time.Duration) (err error)
Add adds the value to cache, but only if the key doesn't already exist.
func (*ShardedLRU) Append ¶
func (c *ShardedLRU) Append(key string, value interface{}) (err error)
Append appends the value to the current key value. The value to append must be a string, []byte or pointer to one of those types.
func (*ShardedLRU) CompareAndSwap ¶
func (c *ShardedLRU) CompareAndSwap(key string, value interface{}, exp time.Duration, cas uint64) (err error)
CompareAndSwap writes the given item that was previously returned by Get, if the value was neither modified or evicted between the Get and the CompareAndSwap calls. The item's Key should not change between calls but all other item fields may differ. ErrCASConflict is returned if the value
was modified in between the calls. ErrNotStored is returned if the value
was evicted in between the calls.
func (*ShardedLRU) Decrement ¶
func (c *ShardedLRU) Decrement(key string, delta uint64) (uint64, error)
Decrement decreases the key's value by delta. The expiration remains the same. The underlying value to increment must be a uint64 or pointer to a uint64.
func (*ShardedLRU) Del ¶
func (c *ShardedLRU) Del(key string) (err error)
Del removes the key from the cache
func (*ShardedLRU) Exists ¶
func (c *ShardedLRU) Exists(key string) bool
Exists returns true if the given key exists
func (*ShardedLRU) Get ¶
func (c *ShardedLRU) Get(key string, dstVal interface{}) (err error)
Get fetches the key into the dstVal. It returns an error if the value doesn't exist.
func (*ShardedLRU) GetItem ¶
func (c *ShardedLRU) GetItem(key string, dstVal interface{}) (cas uint64, err error)
GetItem is similar to Get() only it returns the items unique CAS identifier
func (*ShardedLRU) Increment ¶
func (c *ShardedLRU) Increment(key string, delta uint64) (uint64, error)
Increment increases the key's value by delta. The exipration remains the same. The existing value must be a uint64 or a pointer to a uint64
func (*ShardedLRU) Prepend ¶
func (c *ShardedLRU) Prepend(key string, value interface{}) (err error)
Prepend prepends the value to the current key value. The value to prepend must be a string, []byte or pointer to one of those types.
func (*ShardedLRU) Replace ¶
func (c *ShardedLRU) Replace(key string, value interface{}) (err error)
Replace replaces the current value for the key with the new value, but only if the key already exists. The expiration remains the same.
func (*ShardedLRU) Set ¶
func (c *ShardedLRU) Set(key string, value interface{}, exp time.Duration) (err error)
Set sets the key/value pair
func (*ShardedLRU) SetItem ¶
func (c *ShardedLRU) SetItem(key string, value interface{}, exp time.Duration, cas uint64) (err error)
SetItem sets the item with the given parameters. Use it if you need to specifiy the cas id for future CompareAndSwap actions. Otherwise it's easier to just use Set() instead.
Source Files