/usr/share/gocode/src/github.com/revel/revel/Godeps/_workspace/src/github.com/robfig/go-cache/cache.go is in golang-github-revel-revel-dev 0.12.0+dfsg-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import (
"encoding/binary"
"encoding/gob"
"fmt"
"hash/fnv"
"io"
"os"
"runtime"
"sync"
"time"
)
var (
ErrKeyExists = fmt.Errorf("item already exists")
ErrCacheMiss = fmt.Errorf("item not found")
)
type unexportedInterface interface {
Set(string, interface{}, time.Duration)
Add(string, interface{}, time.Duration) error
Replace(string, interface{}, time.Duration) error
Get(string) (interface{}, bool)
Increment(string, int64) error
IncrementFloat(string, float64) error
Decrement(string, int64) error
Delete(string)
DeleteExpired()
Flush()
Save(io.Writer) error
SaveFile(string) error
Load(io.Reader) error
LoadFile(io.Reader) error
}
type item struct {
Object interface{}
Expiration *time.Time
}
// Returns true if the item has expired.
func (i *item) Expired() bool {
if i.Expiration == nil {
return false
}
return i.Expiration.Before(time.Now())
}
type Cache struct {
*cache
// If this is confusing, see the comment at the bottom of New()
}
type cache struct {
sync.Mutex
defaultExpiration time.Duration
items map[string]*item
janitor *janitor
}
// 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) Set(k string, x interface{}, d time.Duration) {
c.Lock()
c.set(k, x, d)
// TODO: Calls to mu.Unlock are currently not deferred because defer
// adds ~200 ns (as of go1.)
c.Unlock()
}
func (c *cache) set(k string, x interface{}, d time.Duration) {
var e *time.Time
if d == 0 {
d = c.defaultExpiration
}
if d > 0 {
t := time.Now().Add(d)
e = &t
}
c.items[k] = &item{
Object: x,
Expiration: e,
}
}
// 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.Lock()
_, found := c.get(k)
if found {
c.Unlock()
return ErrKeyExists
}
c.set(k, x, d)
c.Unlock()
return nil
}
// Set a new value for the cache key only if it already exists. Returns an
// error if it does not.
func (c *cache) Replace(k string, x interface{}, d time.Duration) error {
c.Lock()
_, found := c.get(k)
if !found {
c.Unlock()
return fmt.Errorf("item %s doesn't exist", k)
}
c.set(k, x, d)
c.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.Lock()
x, found := c.get(k)
c.Unlock()
return x, found
}
func (c *cache) get(k string) (interface{}, bool) {
item, found := c.items[k]
if !found {
return nil, false
}
if item.Expired() {
c.delete(k)
return nil, false
}
return item.Object, true
}
// 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.
func (c *cache) IncrementFloat(k string, n float64) error {
c.Lock()
v, found := c.items[k]
if !found || v.Expired() {
c.Unlock()
return fmt.Errorf("item not found")
}
switch v.Object.(type) {
case float32:
v.Object = v.Object.(float32) + float32(n)
case float64:
v.Object = v.Object.(float64) + n
default:
c.Unlock()
return fmt.Errorf("The value for %s does not have type float32 or float64", k)
}
c.Unlock()
return nil
}
// Increment an item of type int, int8, int16, int32, int64, uintptr, uint,
// uint8, uint32, or uint64 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.
// Wraps around on overlow.
func (c *cache) Increment(k string, n uint64) (uint64, error) {
c.Lock()
defer c.Unlock()
v, found := c.items[k]
if !found || v.Expired() {
return 0, ErrCacheMiss
}
switch v.Object.(type) {
case int:
v.Object = v.Object.(int) + int(n)
return uint64(v.Object.(int)), nil
case int8:
v.Object = v.Object.(int8) + int8(n)
return uint64(v.Object.(int8)), nil
case int16:
v.Object = v.Object.(int16) + int16(n)
return uint64(v.Object.(int16)), nil
case int32:
v.Object = v.Object.(int32) + int32(n)
return uint64(v.Object.(int32)), nil
case int64:
v.Object = v.Object.(int64) + int64(n)
return uint64(v.Object.(int64)), nil
case uint:
v.Object = v.Object.(uint) + uint(n)
return uint64(v.Object.(uint)), nil
case uintptr:
v.Object = v.Object.(uintptr) + uintptr(n)
return uint64(v.Object.(uintptr)), nil
case uint8:
v.Object = v.Object.(uint8) + uint8(n)
return uint64(v.Object.(uint8)), nil
case uint16:
v.Object = v.Object.(uint16) + uint16(n)
return uint64(v.Object.(uint16)), nil
case uint32:
v.Object = v.Object.(uint32) + uint32(n)
return uint64(v.Object.(uint32)), nil
case uint64:
v.Object = v.Object.(uint64) + n
return uint64(v.Object.(uint64)), nil
}
return 0, fmt.Errorf("The value for %s is not an integer", k)
}
// Decrement an item of type int, int8, int16, int32, int64, uintptr, uint,
// uint8, uint32, or uint64 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.
// Stops at 0 on underflow.
func (c *cache) Decrement(k string, n uint64) (uint64, error) {
// TODO: Implement Increment and Decrement more cleanly.
// (Cannot do Increment(k, n*-1) for uints.)
c.Lock()
defer c.Unlock()
v, found := c.items[k]
if !found || v.Expired() {
return 0, ErrCacheMiss
}
switch v.Object.(type) {
case int:
vi := v.Object.(int)
if vi > int(n) {
v.Object = vi - int(n)
} else {
v.Object = int(0)
}
return uint64(v.Object.(int)), nil
case int8:
vi := v.Object.(int8)
if vi > int8(n) {
v.Object = vi - int8(n)
} else {
v.Object = int8(0)
}
return uint64(v.Object.(int8)), nil
case int16:
vi := v.Object.(int16)
if vi > int16(n) {
v.Object = vi - int16(n)
} else {
v.Object = int16(0)
}
return uint64(v.Object.(int16)), nil
case int32:
vi := v.Object.(int32)
if vi > int32(n) {
v.Object = vi - int32(n)
} else {
v.Object = int32(0)
}
return uint64(v.Object.(int32)), nil
case int64:
vi := v.Object.(int64)
if vi > int64(n) {
v.Object = vi - int64(n)
} else {
v.Object = int64(0)
}
return uint64(v.Object.(int64)), nil
case uint:
vi := v.Object.(uint)
if vi > uint(n) {
v.Object = vi - uint(n)
} else {
v.Object = uint(0)
}
return uint64(v.Object.(uint)), nil
case uintptr:
vi := v.Object.(uintptr)
if vi > uintptr(n) {
v.Object = vi - uintptr(n)
} else {
v.Object = uintptr(0)
}
return uint64(v.Object.(uintptr)), nil
case uint8:
vi := v.Object.(uint8)
if vi > uint8(n) {
v.Object = vi - uint8(n)
} else {
v.Object = uint8(0)
}
return uint64(v.Object.(uint8)), nil
case uint16:
vi := v.Object.(uint16)
if vi > uint16(n) {
v.Object = vi - uint16(n)
} else {
v.Object = uint16(0)
}
return uint64(v.Object.(uint16)), nil
case uint32:
vi := v.Object.(uint32)
if vi > uint32(n) {
v.Object = vi - uint32(n)
} else {
v.Object = uint32(0)
}
return uint64(v.Object.(uint32)), nil
case uint64:
vi := v.Object.(uint64)
if vi > uint64(n) {
v.Object = vi - uint64(n)
} else {
v.Object = uint64(0)
}
return uint64(v.Object.(uint64)), nil
}
return 0, fmt.Errorf("The value for %s is not an integer", k)
}
// Delete an item from the cache. Does nothing if the key is not in the cache.
func (c *cache) Delete(k string) (found bool) {
c.Lock()
_, found = c.get(k)
c.delete(k)
c.Unlock()
return
}
func (c *cache) delete(k string) {
delete(c.items, k)
}
// Delete all expired items from the cache.
func (c *cache) DeleteExpired() {
c.Lock()
for k, v := range c.items {
if v.Expired() {
c.delete(k)
}
}
c.Unlock()
}
// Write the cache's items (using Gob) to an io.Writer.
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")
}
}()
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.
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 in the current cache.
func (c *cache) Load(r io.Reader) error {
dec := gob.NewDecoder(r)
items := map[string]*item{}
err := dec.Decode(&items)
if err == nil {
for k, v := range items {
_, found := c.items[k]
if !found {
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.
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()
}
// Delete all items from the cache.
func (c *cache) Flush() {
c.Lock()
c.items = map[string]*item{}
c.Unlock()
}
type janitor struct {
Interval time.Duration
stop chan bool
}
func (j *janitor) Run(c *cache) {
j.stop = make(chan bool)
tick := time.Tick(j.Interval)
for {
select {
case <-tick:
c.DeleteExpired()
case <-j.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) *cache {
if de == 0 {
de = -1
}
c := &cache{
defaultExpiration: de,
items: map[string]*item{},
}
return c
}
// 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 New(defaultExpiration, cleanupInterval time.Duration) *Cache {
c := newCache(defaultExpiration)
// 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 cleanupInterval > 0 {
runJanitor(c, cleanupInterval)
runtime.SetFinalizer(C, stopJanitor)
}
return C
}
type unexportedShardedCache struct {
*shardedCache
}
type shardedCache struct {
m uint32
cs []*cache
janitor *shardedJanitor
}
func (sc *shardedCache) bucket(k string) *cache {
h := fnv.New32()
h.Write([]byte(k))
n := binary.BigEndian.Uint32(h.Sum(nil))
return sc.cs[n%sc.m]
}
func (sc *shardedCache) Set(k string, x interface{}, d time.Duration) {
sc.bucket(k).Set(k, x, d)
}
func (sc *shardedCache) Add(k string, x interface{}, d time.Duration) error {
return sc.bucket(k).Add(k, x, d)
}
func (sc *shardedCache) Replace(k string, x interface{}, d time.Duration) error {
return sc.bucket(k).Replace(k, x, d)
}
func (sc *shardedCache) Get(k string) (interface{}, bool) {
return sc.bucket(k).Get(k)
}
func (sc *shardedCache) Increment(k string, n uint64) (uint64, error) {
return sc.bucket(k).Increment(k, n)
}
func (sc *shardedCache) IncrementFloat(k string, n float64) error {
return sc.bucket(k).IncrementFloat(k, n)
}
func (sc *shardedCache) Decrement(k string, n uint64) (uint64, error) {
return sc.bucket(k).Decrement(k, n)
}
func (sc *shardedCache) Delete(k string) {
sc.bucket(k).Delete(k)
}
func (sc *shardedCache) DeleteExpired() {
for _, v := range sc.cs {
v.DeleteExpired()
}
}
func (sc *shardedCache) Flush() {
for _, v := range sc.cs {
v.Flush()
}
}
type shardedJanitor struct {
Interval time.Duration
stop chan bool
}
func (j *shardedJanitor) Run(sc *shardedCache) {
j.stop = make(chan bool)
tick := time.Tick(j.Interval)
for {
select {
case <-tick:
sc.DeleteExpired()
case <-j.stop:
return
}
}
}
func stopShardedJanitor(sc *unexportedShardedCache) {
sc.janitor.stop <- true
}
func runShardedJanitor(sc *shardedCache, ci time.Duration) {
j := &shardedJanitor{
Interval: ci,
}
sc.janitor = j
go j.Run(sc)
}
func newShardedCache(n int, de time.Duration) *shardedCache {
sc := &shardedCache{
m: uint32(n - 1),
cs: make([]*cache, n),
}
for i := 0; i < n; i++ {
c := &cache{
defaultExpiration: de,
items: map[string]*item{},
}
sc.cs[i] = c
}
return sc
}
func unexportedNewSharded(shards int, defaultExpiration, cleanupInterval time.Duration) *unexportedShardedCache {
if defaultExpiration == 0 {
defaultExpiration = -1
}
sc := newShardedCache(shards, defaultExpiration)
SC := &unexportedShardedCache{sc}
if cleanupInterval > 0 {
runShardedJanitor(sc, cleanupInterval)
runtime.SetFinalizer(SC, stopShardedJanitor)
}
return SC
}
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