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e7a9def Nov 25, 2016
@patrickmn @temoto @databus23
1132 lines (1068 sloc) 29.4 KB
package cache
import (
"encoding/gob"
"fmt"
"io"
"os"
"runtime"
"sync"
"time"
)
type Item struct {
Object interface{}
Expiration int64
}
// Returns true if the item has expired.
func (item Item) Expired() bool {
if item.Expiration == 0 {
return false
}
return time.Now().UnixNano() > item.Expiration
}
const (
// For use with functions that take an expiration time.
NoExpiration time.Duration = -1
// For use with functions that take an expiration time. Equivalent to
// passing in the same expiration duration as was given to New() or
// NewFrom() when the cache was created (e.g. 5 minutes.)
DefaultExpiration time.Duration = 0
)
type Cache struct {
*cache
// If this is confusing, see the comment at the bottom of New()
}
type cache struct {
defaultExpiration time.Duration
items map[string]Item
mu sync.RWMutex
onEvicted func(string, interface{})
janitor *janitor
}
// Add an item to the cache, replacing any existing item. If the duration is 0
// (DefaultExpiration), the cache's default expiration time is used. If it is -1
// (NoExpiration), the item never expires.
func (c *cache) Set(k string, x interface{}, d time.Duration) {
// "Inlining" of set
var e int64
if d == DefaultExpiration {
d = c.defaultExpiration
}
if d > 0 {
e = time.Now().Add(d).UnixNano()
}
c.mu.Lock()
c.items[k] = Item{
Object: x,
Expiration: e,
}
// TODO: Calls to mu.Unlock are currently not deferred because defer
// adds ~200 ns (as of go1.)
c.mu.Unlock()
}
func (c *cache) set(k string, x interface{}, d time.Duration) {
var e int64
if d == DefaultExpiration {
d = c.defaultExpiration
}
if d > 0 {
e = time.Now().Add(d).UnixNano()
}
c.items[k] = Item{
Object: x,
Expiration: e,
}
}
// Add an item to the cache, replacing any existing item, using the default
// expiration.
func (c *cache) SetDefault(k string, x interface{}) {
c.Set(k, x, DefaultExpiration)
}
// 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 (c *cache) Add(k string, x interface{}, d time.Duration) error {
c.mu.Lock()
_, found := c.get(k)
if found {
c.mu.Unlock()
return fmt.Errorf("Item %s already exists", k)
}
c.set(k, x, d)
c.mu.Unlock()
return nil
}
// Set a new value for the cache key only if it already exists, and the existing
// item hasn't expired. Returns an error otherwise.
func (c *cache) Replace(k string, x interface{}, d time.Duration) error {
c.mu.Lock()
_, found := c.get(k)
if !found {
c.mu.Unlock()
return fmt.Errorf("Item %s doesn't exist", k)
}
c.set(k, x, d)
c.mu.Unlock()
return nil
}
// Get an item from the cache. Returns the item or nil, and a bool indicating
// whether the key was found.
func (c *cache) Get(k string) (interface{}, bool) {
c.mu.RLock()
// "Inlining" of get and Expired
item, found := c.items[k]
if !found {
c.mu.RUnlock()
return nil, false
}
if item.Expiration > 0 {
if time.Now().UnixNano() > item.Expiration {
c.mu.RUnlock()
return nil, false
}
}
c.mu.RUnlock()
return item.Object, true
}
func (c *cache) get(k string) (interface{}, bool) {
item, found := c.items[k]
if !found {
return nil, false
}
// "Inlining" of Expired
if item.Expiration > 0 {
if time.Now().UnixNano() > item.Expiration {
return nil, false
}
}
return item.Object, true
}
// 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) Increment(k string, n int64) error {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return fmt.Errorf("Item %s not found", k)
}
switch v.Object.(type) {
case int:
v.Object = v.Object.(int) + int(n)
case int8:
v.Object = v.Object.(int8) + int8(n)
case int16:
v.Object = v.Object.(int16) + int16(n)
case int32:
v.Object = v.Object.(int32) + int32(n)
case int64:
v.Object = v.Object.(int64) + n
case uint:
v.Object = v.Object.(uint) + uint(n)
case uintptr:
v.Object = v.Object.(uintptr) + uintptr(n)
case uint8:
v.Object = v.Object.(uint8) + uint8(n)
case uint16:
v.Object = v.Object.(uint16) + uint16(n)
case uint32:
v.Object = v.Object.(uint32) + uint32(n)
case uint64:
v.Object = v.Object.(uint64) + uint64(n)
case float32:
v.Object = v.Object.(float32) + float32(n)
case float64:
v.Object = v.Object.(float64) + float64(n)
default:
c.mu.Unlock()
return fmt.Errorf("The value for %s is not an integer", k)
}
c.items[k] = v
c.mu.Unlock()
return nil
}
// 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 (c *cache) IncrementFloat(k string, n float64) error {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return fmt.Errorf("Item %s not found", k)
}
switch v.Object.(type) {
case float32:
v.Object = v.Object.(float32) + float32(n)
case float64:
v.Object = v.Object.(float64) + n
default:
c.mu.Unlock()
return fmt.Errorf("The value for %s does not have type float32 or float64", k)
}
c.items[k] = v
c.mu.Unlock()
return nil
}
// 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) IncrementInt(k string, n int) (int, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(int)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an int", k)
}
nv := rv + n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) IncrementInt8(k string, n int8) (int8, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(int8)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an int8", k)
}
nv := rv + n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) IncrementInt16(k string, n int16) (int16, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(int16)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an int16", k)
}
nv := rv + n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) IncrementInt32(k string, n int32) (int32, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(int32)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an int32", k)
}
nv := rv + n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) IncrementInt64(k string, n int64) (int64, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(int64)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an int64", k)
}
nv := rv + n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) IncrementUint(k string, n uint) (uint, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(uint)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an uint", k)
}
nv := rv + n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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 (c *cache) IncrementUintptr(k string, n uintptr) (uintptr, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(uintptr)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an uintptr", k)
}
nv := rv + n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) IncrementUint8(k string, n uint8) (uint8, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(uint8)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an uint8", k)
}
nv := rv + n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) IncrementUint16(k string, n uint16) (uint16, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(uint16)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an uint16", k)
}
nv := rv + n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) IncrementUint32(k string, n uint32) (uint32, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(uint32)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an uint32", k)
}
nv := rv + n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) IncrementUint64(k string, n uint64) (uint64, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(uint64)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an uint64", k)
}
nv := rv + n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) IncrementFloat32(k string, n float32) (float32, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(float32)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an float32", k)
}
nv := rv + n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) IncrementFloat64(k string, n float64) (float64, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(float64)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an float64", k)
}
nv := rv + n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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 (c *cache) Decrement(k string, n int64) error {
// TODO: Implement Increment and Decrement more cleanly.
// (Cannot do Increment(k, n*-1) for uints.)
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return fmt.Errorf("Item not found")
}
switch v.Object.(type) {
case int:
v.Object = v.Object.(int) - int(n)
case int8:
v.Object = v.Object.(int8) - int8(n)
case int16:
v.Object = v.Object.(int16) - int16(n)
case int32:
v.Object = v.Object.(int32) - int32(n)
case int64:
v.Object = v.Object.(int64) - n
case uint:
v.Object = v.Object.(uint) - uint(n)
case uintptr:
v.Object = v.Object.(uintptr) - uintptr(n)
case uint8:
v.Object = v.Object.(uint8) - uint8(n)
case uint16:
v.Object = v.Object.(uint16) - uint16(n)
case uint32:
v.Object = v.Object.(uint32) - uint32(n)
case uint64:
v.Object = v.Object.(uint64) - uint64(n)
case float32:
v.Object = v.Object.(float32) - float32(n)
case float64:
v.Object = v.Object.(float64) - float64(n)
default:
c.mu.Unlock()
return fmt.Errorf("The value for %s is not an integer", k)
}
c.items[k] = v
c.mu.Unlock()
return nil
}
// 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 (c *cache) DecrementFloat(k string, n float64) error {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return fmt.Errorf("Item %s not found", k)
}
switch v.Object.(type) {
case float32:
v.Object = v.Object.(float32) - float32(n)
case float64:
v.Object = v.Object.(float64) - n
default:
c.mu.Unlock()
return fmt.Errorf("The value for %s does not have type float32 or float64", k)
}
c.items[k] = v
c.mu.Unlock()
return nil
}
// 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) DecrementInt(k string, n int) (int, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(int)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an int", k)
}
nv := rv - n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) DecrementInt8(k string, n int8) (int8, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(int8)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an int8", k)
}
nv := rv - n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) DecrementInt16(k string, n int16) (int16, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(int16)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an int16", k)
}
nv := rv - n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) DecrementInt32(k string, n int32) (int32, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(int32)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an int32", k)
}
nv := rv - n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) DecrementInt64(k string, n int64) (int64, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(int64)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an int64", k)
}
nv := rv - n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) DecrementUint(k string, n uint) (uint, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(uint)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an uint", k)
}
nv := rv - n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) DecrementUintptr(k string, n uintptr) (uintptr, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(uintptr)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an uintptr", k)
}
nv := rv - n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) DecrementUint8(k string, n uint8) (uint8, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(uint8)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an uint8", k)
}
nv := rv - n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) DecrementUint16(k string, n uint16) (uint16, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(uint16)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an uint16", k)
}
nv := rv - n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) DecrementUint32(k string, n uint32) (uint32, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(uint32)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an uint32", k)
}
nv := rv - n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) DecrementUint64(k string, n uint64) (uint64, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(uint64)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an uint64", k)
}
nv := rv - n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) DecrementFloat32(k string, n float32) (float32, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(float32)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an float32", k)
}
nv := rv - n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// 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) DecrementFloat64(k string, n float64) (float64, error) {
c.mu.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.mu.Unlock()
return 0, fmt.Errorf("Item %s not found", k)
}
rv, ok := v.Object.(float64)
if !ok {
c.mu.Unlock()
return 0, fmt.Errorf("The value for %s is not an float64", k)
}
nv := rv - n
v.Object = nv
c.items[k] = v
c.mu.Unlock()
return nv, nil
}
// Delete an item from the cache. Does nothing if the key is not in the cache.
func (c *cache) Delete(k string) {
c.mu.Lock()
v, evicted := c.delete(k)
c.mu.Unlock()
if evicted {
c.onEvicted(k, v)
}
}
func (c *cache) delete(k string) (interface{}, bool) {
if c.onEvicted != nil {
if v, found := c.items[k]; found {
delete(c.items, k)
return v.Object, true
}
}
delete(c.items, k)
return nil, false
}
type keyAndValue struct {
key string
value interface{}
}
// Delete all expired items from the cache.
func (c *cache) DeleteExpired() {
var evictedItems []keyAndValue
now := time.Now().UnixNano()
c.mu.Lock()
for k, v := range c.items {
// "Inlining" of expired
if v.Expiration > 0 && now > v.Expiration {
ov, evicted := c.delete(k)
if evicted {
evictedItems = append(evictedItems, keyAndValue{k, ov})
}
}
}
c.mu.Unlock()
for _, v := range evictedItems {
c.onEvicted(v.key, v.value)
}
}
// Sets an (optional) function that is called with the key and value when an
// item is evicted from the cache. (Including when it is deleted manually, but
// not when it is overwritten.) Set to nil to disable.
func (c *cache) OnEvicted(f func(string, interface{})) {
c.mu.Lock()
c.onEvicted = f
c.mu.Unlock()
}
// Write the cache's items (using Gob) to an io.Writer.
//
// NOTE: This method is deprecated in favor of c.Items() and NewFrom() (see the
// documentation for NewFrom().)
func (c *cache) Save(w io.Writer) (err error) {
enc := gob.NewEncoder(w)
defer func() {
if x := recover(); x != nil {
err = fmt.Errorf("Error registering item types with Gob library")
}
}()
c.mu.RLock()
defer c.mu.RUnlock()
for _, v := range c.items {
gob.Register(v.Object)
}
err = enc.Encode(&c.items)
return
}
// Save the cache's items to the given filename, creating the file if it
// doesn't exist, and overwriting it if it does.
//
// NOTE: This method is deprecated in favor of c.Items() and NewFrom() (see the
// documentation for NewFrom().)
func (c *cache) SaveFile(fname string) error {
fp, err := os.Create(fname)
if err != nil {
return err
}
err = c.Save(fp)
if err != nil {
fp.Close()
return err
}
return fp.Close()
}
// 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.
//
// NOTE: This method is deprecated in favor of c.Items() and NewFrom() (see the
// documentation for NewFrom().)
func (c *cache) Load(r io.Reader) error {
dec := gob.NewDecoder(r)
items := map[string]Item{}
err := dec.Decode(&items)
if err == nil {
c.mu.Lock()
defer c.mu.Unlock()
for k, v := range items {
ov, found := c.items[k]
if !found || ov.Expired() {
c.items[k] = v
}
}
}
return err
}
// Load and add cache items from the given filename, excluding any items with
// keys that already exist in the current cache.
//
// NOTE: This method is deprecated in favor of c.Items() and NewFrom() (see the
// documentation for NewFrom().)
func (c *cache) LoadFile(fname string) error {
fp, err := os.Open(fname)
if err != nil {
return err
}
err = c.Load(fp)
if err != nil {
fp.Close()
return err
}
return fp.Close()
}
// Copies all unexpired items in the cache into a new map and returns it.
func (c *cache) Items() map[string]Item {
c.mu.RLock()
defer c.mu.RUnlock()
m := make(map[string]Item, len(c.items))
now := time.Now().UnixNano()
for k, v := range c.items {
// "Inlining" of Expired
if v.Expiration > 0 {
if now > v.Expiration {
continue
}
}
m[k] = v
}
return m
}
// Returns the number of items in the cache. This may include items that have
// expired, but have not yet been cleaned up.
func (c *cache) ItemCount() int {
c.mu.RLock()
n := len(c.items)
c.mu.RUnlock()
return n
}
// Delete all items from the cache.
func (c *cache) Flush() {
c.mu.Lock()
c.items = map[string]Item{}
c.mu.Unlock()
}
type janitor struct {
Interval time.Duration
stop chan bool
}
func (j *janitor) Run(c *cache) {
j.stop = make(chan bool)
ticker := time.NewTicker(j.Interval)
for {
select {
case <-ticker.C:
c.DeleteExpired()
case <-j.stop:
ticker.Stop()
return
}
}
}
func stopJanitor(c *Cache) {
c.janitor.stop <- true
}
func runJanitor(c *cache, ci time.Duration) {
j := &janitor{
Interval: ci,
}
c.janitor = j
go j.Run(c)
}
func newCache(de time.Duration, m map[string]Item) *cache {
if de == 0 {
de = -1
}
c := &cache{
defaultExpiration: de,
items: m,
}
return c
}
func newCacheWithJanitor(de time.Duration, ci time.Duration, m map[string]Item) *Cache {
c := newCache(de, m)
// This trick ensures that the janitor goroutine (which--granted it
// was enabled--is running DeleteExpired on c forever) does not keep
// the returned C object from being garbage collected. When it is
// garbage collected, the finalizer stops the janitor goroutine, after
// which c can be collected.
C := &Cache{c}
if ci > 0 {
runJanitor(c, ci)
runtime.SetFinalizer(C, stopJanitor)
}
return C
}
// Return a new cache with a given default expiration duration and cleanup
// interval. If the expiration duration is less than one (or NoExpiration),
// 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 c.DeleteExpired().
func New(defaultExpiration, cleanupInterval time.Duration) *Cache {
items := make(map[string]Item)
return newCacheWithJanitor(defaultExpiration, cleanupInterval, items)
}
// Return a new cache with a given default expiration duration and cleanup
// interval. If the expiration duration is less than one (or NoExpiration),
// 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 c.DeleteExpired().
//
// NewFrom() also accepts an items map which will serve as the underlying map
// for the cache. This is useful for starting from a deserialized cache
// (serialized using e.g. gob.Encode() on c.Items()), or passing in e.g.
// make(map[string]Item, 500) to improve startup performance when the cache
// is expected to reach a certain minimum size.
//
// Only the cache's methods synchronize access to this map, so it is not
// recommended to keep any references to the map around after creating a cache.
// If need be, the map can be accessed at a later point using c.Items() (subject
// to the same caveat.)
//
// Note regarding serialization: When using e.g. gob, make sure to
// gob.Register() the individual types stored in the cache before encoding a
// map retrieved with c.Items(), and to register those same types before
// decoding a blob containing an items map.
func NewFrom(defaultExpiration, cleanupInterval time.Duration, items map[string]Item) *Cache {
return newCacheWithJanitor(defaultExpiration, cleanupInterval, items)
}