2020-12-30 07:08:20 +01:00
|
|
|
package gocache
|
|
|
|
|
|
|
|
import (
|
|
|
|
"errors"
|
2021-01-13 03:08:18 +01:00
|
|
|
"reflect"
|
2020-12-30 07:08:20 +01:00
|
|
|
"sync"
|
|
|
|
"time"
|
|
|
|
)
|
|
|
|
|
2021-01-13 03:08:18 +01:00
|
|
|
var (
|
2020-12-30 07:08:20 +01:00
|
|
|
Debug = false
|
2021-01-13 03:08:18 +01:00
|
|
|
)
|
2020-12-30 07:08:20 +01:00
|
|
|
|
2021-01-13 03:08:18 +01:00
|
|
|
const (
|
2020-12-30 07:08:20 +01:00
|
|
|
// NoMaxSize means that the cache has no maximum number of entries in the cache
|
|
|
|
// Setting Cache.maxSize to this value also means there will be no eviction
|
|
|
|
NoMaxSize = 0
|
|
|
|
|
|
|
|
// NoMaxMemoryUsage means that the cache has no maximum number of entries in the cache
|
|
|
|
NoMaxMemoryUsage = 0
|
|
|
|
|
|
|
|
// DefaultMaxSize is the max size set if no max size is specified
|
|
|
|
DefaultMaxSize = 100000
|
|
|
|
|
|
|
|
// NoExpiration is the value that must be used as TTL to specify that the given key should never expire
|
|
|
|
NoExpiration = -1
|
|
|
|
|
|
|
|
Kilobyte = 1024
|
2021-01-13 03:08:18 +01:00
|
|
|
Megabyte = 1024 * Kilobyte
|
|
|
|
Gigabyte = 1024 * Megabyte
|
2020-12-30 07:08:20 +01:00
|
|
|
)
|
|
|
|
|
|
|
|
var (
|
2021-01-13 03:08:18 +01:00
|
|
|
ErrKeyDoesNotExist = errors.New("key does not exist")
|
|
|
|
ErrKeyHasNoExpiration = errors.New("key has no expiration")
|
|
|
|
ErrJanitorAlreadyRunning = errors.New("janitor is already running")
|
2020-12-30 07:08:20 +01:00
|
|
|
)
|
|
|
|
|
|
|
|
// Cache is the core struct of gocache which contains the data as well as all relevant configuration fields
|
|
|
|
type Cache struct {
|
|
|
|
// maxSize is the maximum amount of entries that can be in the cache at any given time
|
|
|
|
// By default, this is set to DefaultMaxSize
|
|
|
|
maxSize int
|
|
|
|
|
|
|
|
// maxMemoryUsage is the maximum amount of memory that can be taken up by the cache at any time
|
|
|
|
// By default, this is set to NoMaxMemoryUsage, meaning that the default behavior is to not evict
|
|
|
|
// based on maximum memory usage
|
|
|
|
maxMemoryUsage int
|
|
|
|
|
|
|
|
// evictionPolicy is the eviction policy
|
|
|
|
evictionPolicy EvictionPolicy
|
|
|
|
|
|
|
|
// stats is the object that contains cache statistics/metrics
|
|
|
|
stats *Statistics
|
|
|
|
|
|
|
|
// entries is the content of the cache
|
|
|
|
entries map[string]*Entry
|
|
|
|
|
|
|
|
// mutex is the lock for making concurrent operations on the cache
|
|
|
|
mutex sync.RWMutex
|
|
|
|
|
|
|
|
// head is the cache entry at the head of the cache
|
|
|
|
head *Entry
|
|
|
|
|
|
|
|
// tail is the last cache node and also the next entry that will be evicted
|
|
|
|
tail *Entry
|
|
|
|
|
|
|
|
// stopJanitor is the channel used to stop the janitor
|
|
|
|
stopJanitor chan bool
|
|
|
|
|
|
|
|
// memoryUsage is the approximate memory usage of the cache (dataset only) in bytes
|
|
|
|
memoryUsage int
|
2021-01-13 03:08:18 +01:00
|
|
|
|
|
|
|
// forceNilInterfaceOnNilPointer determines whether all Set-like functions should set a value as nil if the
|
|
|
|
// interface passed has a nil value but not a nil type.
|
|
|
|
//
|
|
|
|
// By default, interfaces are only nil when both their type and value is nil.
|
|
|
|
// This means that when you pass a pointer to a nil value, the type of the interface
|
|
|
|
// will still show as nil, which means that if you don't cast the interface after
|
|
|
|
// retrieving it, a nil check will return that the value is not false.
|
|
|
|
forceNilInterfaceOnNilPointer bool
|
2020-12-30 07:08:20 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
// MaxSize returns the maximum amount of keys that can be present in the cache before
|
|
|
|
// new entries trigger the eviction of the tail
|
|
|
|
func (cache *Cache) MaxSize() int {
|
|
|
|
return cache.maxSize
|
|
|
|
}
|
|
|
|
|
|
|
|
// MaxMemoryUsage returns the configured maxMemoryUsage of the cache
|
|
|
|
func (cache *Cache) MaxMemoryUsage() int {
|
|
|
|
return cache.maxMemoryUsage
|
|
|
|
}
|
|
|
|
|
|
|
|
// EvictionPolicy returns the EvictionPolicy of the Cache
|
|
|
|
func (cache *Cache) EvictionPolicy() EvictionPolicy {
|
|
|
|
return cache.evictionPolicy
|
|
|
|
}
|
|
|
|
|
|
|
|
// Stats returns statistics from the cache
|
2021-01-13 03:08:18 +01:00
|
|
|
func (cache *Cache) Stats() Statistics {
|
|
|
|
cache.mutex.RLock()
|
|
|
|
stats := Statistics{
|
|
|
|
EvictedKeys: cache.stats.EvictedKeys,
|
|
|
|
ExpiredKeys: cache.stats.ExpiredKeys,
|
|
|
|
Hits: cache.stats.Hits,
|
|
|
|
Misses: cache.stats.Misses,
|
|
|
|
}
|
|
|
|
cache.mutex.RUnlock()
|
|
|
|
return stats
|
2020-12-30 07:08:20 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
// MemoryUsage returns the current memory usage of the cache's dataset in bytes
|
|
|
|
// If MaxMemoryUsage is set to NoMaxMemoryUsage, this will return 0
|
|
|
|
func (cache *Cache) MemoryUsage() int {
|
|
|
|
return cache.memoryUsage
|
|
|
|
}
|
|
|
|
|
|
|
|
// WithMaxSize sets the maximum amount of entries that can be in the cache at any given time
|
|
|
|
// A maxSize of 0 or less means infinite
|
|
|
|
func (cache *Cache) WithMaxSize(maxSize int) *Cache {
|
|
|
|
if maxSize < 0 {
|
|
|
|
maxSize = NoMaxSize
|
|
|
|
}
|
2021-01-13 03:08:18 +01:00
|
|
|
if maxSize != NoMaxSize && cache.Count() == 0 {
|
|
|
|
cache.entries = make(map[string]*Entry, maxSize)
|
|
|
|
}
|
2020-12-30 07:08:20 +01:00
|
|
|
cache.maxSize = maxSize
|
|
|
|
return cache
|
|
|
|
}
|
|
|
|
|
|
|
|
// WithMaxMemoryUsage sets the maximum amount of memory that can be used by the cache at any given time
|
|
|
|
//
|
|
|
|
// NOTE: This is approximate.
|
|
|
|
//
|
|
|
|
// Setting this to NoMaxMemoryUsage will disable eviction by memory usage
|
|
|
|
func (cache *Cache) WithMaxMemoryUsage(maxMemoryUsageInBytes int) *Cache {
|
|
|
|
if maxMemoryUsageInBytes < 0 {
|
|
|
|
maxMemoryUsageInBytes = NoMaxMemoryUsage
|
|
|
|
}
|
|
|
|
cache.maxMemoryUsage = maxMemoryUsageInBytes
|
|
|
|
return cache
|
|
|
|
}
|
|
|
|
|
|
|
|
// WithEvictionPolicy sets eviction algorithm.
|
|
|
|
// Defaults to FirstInFirstOut (FIFO)
|
|
|
|
func (cache *Cache) WithEvictionPolicy(policy EvictionPolicy) *Cache {
|
|
|
|
cache.evictionPolicy = policy
|
|
|
|
return cache
|
|
|
|
}
|
|
|
|
|
2021-01-13 03:08:18 +01:00
|
|
|
// WithForceNilInterfaceOnNilPointer sets whether all Set-like functions should set a value as nil if the
|
|
|
|
// interface passed has a nil value but not a nil type.
|
|
|
|
//
|
|
|
|
// In Go, an interface is only nil if both its type and value are nil, which means that a nil pointer
|
|
|
|
// (e.g. (*Struct)(nil)) will retain its attribution to the type, and the unmodified value returned from
|
|
|
|
// Cache.Get, for instance, would return false when compared with nil if this option is set to false.
|
|
|
|
//
|
|
|
|
// We can bypass this by detecting if the interface's value is nil and setting it to nil rather than
|
|
|
|
// a nil pointer, which will make the value returned from Cache.Get return true when compared with nil.
|
|
|
|
// This is exactly what passing true to WithForceNilInterfaceOnNilPointer does, and it's also the default behavior.
|
|
|
|
//
|
|
|
|
// Alternatively, you may pass false to WithForceNilInterfaceOnNilPointer, which will mean that you'll have
|
|
|
|
// to cast the value returned from Cache.Get to its original type to check for whether the pointer returned
|
|
|
|
// is nil or not.
|
|
|
|
//
|
|
|
|
// If set to true:
|
|
|
|
// cache := gocache.NewCache().WithForceNilInterfaceOnNilPointer(true)
|
|
|
|
// cache.Set("key", (*Struct)(nil))
|
|
|
|
// value, _ := cache.Get("key")
|
|
|
|
// // the following returns true, because the interface{} was forcefully set to nil
|
|
|
|
// if value == nil {}
|
|
|
|
// // the following will panic, because the value has been casted to its type
|
|
|
|
// if value.(*Struct) == nil {}
|
|
|
|
//
|
|
|
|
// If set to false:
|
|
|
|
// cache := gocache.NewCache().WithForceNilInterfaceOnNilPointer(false)
|
|
|
|
// cache.Set("key", (*Struct)(nil))
|
|
|
|
// value, _ := cache.Get("key")
|
|
|
|
// // the following returns false, because the interface{} returned has a non-nil type (*Struct)
|
|
|
|
// if value == nil {}
|
|
|
|
// // the following returns true, because the value has been casted to its type
|
|
|
|
// if value.(*Struct) == nil {}
|
|
|
|
//
|
|
|
|
// In other words, if set to true, you do not need to cast the value returned from the cache to
|
|
|
|
// to check if the value is nil.
|
|
|
|
//
|
|
|
|
// Defaults to true
|
|
|
|
func (cache *Cache) WithForceNilInterfaceOnNilPointer(forceNilInterfaceOnNilPointer bool) *Cache {
|
|
|
|
cache.forceNilInterfaceOnNilPointer = forceNilInterfaceOnNilPointer
|
|
|
|
return cache
|
|
|
|
}
|
|
|
|
|
2020-12-30 07:08:20 +01:00
|
|
|
// NewCache creates a new Cache
|
|
|
|
//
|
|
|
|
// Should be used in conjunction with Cache.WithMaxSize, Cache.WithMaxMemoryUsage and/or Cache.WithEvictionPolicy
|
|
|
|
// gocache.NewCache().WithMaxSize(10000).WithEvictionPolicy(gocache.LeastRecentlyUsed)
|
|
|
|
//
|
|
|
|
func NewCache() *Cache {
|
|
|
|
return &Cache{
|
2021-01-13 03:08:18 +01:00
|
|
|
maxSize: DefaultMaxSize,
|
|
|
|
evictionPolicy: FirstInFirstOut,
|
|
|
|
stats: &Statistics{},
|
|
|
|
entries: make(map[string]*Entry),
|
|
|
|
mutex: sync.RWMutex{},
|
|
|
|
stopJanitor: nil,
|
|
|
|
forceNilInterfaceOnNilPointer: true,
|
2020-12-30 07:08:20 +01:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// Set creates or updates a key with a given value
|
|
|
|
func (cache *Cache) Set(key string, value interface{}) {
|
|
|
|
cache.SetWithTTL(key, value, NoExpiration)
|
|
|
|
}
|
|
|
|
|
|
|
|
// SetWithTTL creates or updates a key with a given value and sets an expiration time (-1 is NoExpiration)
|
2021-01-13 03:08:18 +01:00
|
|
|
//
|
|
|
|
// The TTL provided must be greater than 0, or NoExpiration (-1). If a negative value that isn't -1 (NoExpiration) is
|
|
|
|
// provided, the entry will not be created if the key doesn't exist
|
2020-12-30 07:08:20 +01:00
|
|
|
func (cache *Cache) SetWithTTL(key string, value interface{}, ttl time.Duration) {
|
2021-01-13 03:08:18 +01:00
|
|
|
// An interface is only nil if both its value and its type are nil, however, passing a pointer
|
|
|
|
if cache.forceNilInterfaceOnNilPointer {
|
|
|
|
if value != nil && (reflect.ValueOf(value).Kind() == reflect.Ptr && reflect.ValueOf(value).IsNil()) {
|
|
|
|
value = nil
|
|
|
|
}
|
|
|
|
}
|
2020-12-30 07:08:20 +01:00
|
|
|
cache.mutex.Lock()
|
|
|
|
entry, ok := cache.get(key)
|
|
|
|
if !ok {
|
2021-01-13 03:08:18 +01:00
|
|
|
// A negative TTL that isn't -1 (NoExpiration) or 0 is an entry that will expire instantly,
|
2020-12-30 07:08:20 +01:00
|
|
|
// so might as well just not create it in the first place
|
2021-01-13 03:08:18 +01:00
|
|
|
if ttl != NoExpiration && ttl < 1 {
|
2020-12-30 07:08:20 +01:00
|
|
|
cache.mutex.Unlock()
|
|
|
|
return
|
|
|
|
}
|
|
|
|
// Cache entry doesn't exist, so we have to create a new one
|
|
|
|
entry = &Entry{
|
|
|
|
Key: key,
|
|
|
|
Value: value,
|
|
|
|
RelevantTimestamp: time.Now(),
|
|
|
|
previous: cache.head,
|
|
|
|
}
|
|
|
|
if cache.head == nil {
|
|
|
|
cache.tail = entry
|
|
|
|
} else {
|
|
|
|
cache.head.next = entry
|
|
|
|
}
|
|
|
|
cache.head = entry
|
|
|
|
cache.entries[key] = entry
|
|
|
|
if cache.maxMemoryUsage != NoMaxMemoryUsage {
|
|
|
|
cache.memoryUsage += entry.SizeInBytes()
|
|
|
|
}
|
|
|
|
} else {
|
2021-01-13 03:08:18 +01:00
|
|
|
// A negative TTL that isn't -1 (NoExpiration) or 0 is an entry that will expire instantly,
|
|
|
|
// so might as well just delete it immediately instead of updating it
|
|
|
|
if ttl != NoExpiration && ttl < 1 {
|
|
|
|
cache.delete(key)
|
|
|
|
cache.mutex.Unlock()
|
|
|
|
return
|
|
|
|
}
|
2020-12-30 07:08:20 +01:00
|
|
|
if cache.maxMemoryUsage != NoMaxMemoryUsage {
|
|
|
|
// Substract the old entry from the cache's memoryUsage
|
|
|
|
cache.memoryUsage -= entry.SizeInBytes()
|
|
|
|
}
|
|
|
|
// Update existing entry's value
|
|
|
|
entry.Value = value
|
|
|
|
entry.RelevantTimestamp = time.Now()
|
|
|
|
if cache.maxMemoryUsage != NoMaxMemoryUsage {
|
|
|
|
// Add the memory usage of the new entry to the cache's memoryUsage
|
|
|
|
cache.memoryUsage += entry.SizeInBytes()
|
|
|
|
}
|
|
|
|
// Because we just updated the entry, we need to move it back to HEAD
|
|
|
|
cache.moveExistingEntryToHead(entry)
|
|
|
|
}
|
|
|
|
if ttl != NoExpiration {
|
|
|
|
entry.Expiration = time.Now().Add(ttl).UnixNano()
|
|
|
|
} else {
|
|
|
|
entry.Expiration = NoExpiration
|
|
|
|
}
|
|
|
|
// If the cache doesn't have a maxSize/maxMemoryUsage, then there's no point checking if we need to evict
|
|
|
|
// an entry, so we'll just return now
|
|
|
|
if cache.maxSize == NoMaxSize && cache.maxMemoryUsage == NoMaxMemoryUsage {
|
|
|
|
cache.mutex.Unlock()
|
|
|
|
return
|
|
|
|
}
|
|
|
|
// If there's a maxSize and the cache has more entries than the maxSize, evict
|
|
|
|
if cache.maxSize != NoMaxSize && len(cache.entries) > cache.maxSize {
|
|
|
|
cache.evict()
|
|
|
|
}
|
|
|
|
// If there's a maxMemoryUsage and the memoryUsage is above the maxMemoryUsage, evict
|
|
|
|
if cache.maxMemoryUsage != NoMaxMemoryUsage && cache.memoryUsage > cache.maxMemoryUsage {
|
|
|
|
for cache.memoryUsage > cache.maxMemoryUsage && len(cache.entries) > 0 {
|
|
|
|
cache.evict()
|
|
|
|
}
|
|
|
|
}
|
|
|
|
cache.mutex.Unlock()
|
|
|
|
}
|
|
|
|
|
|
|
|
// SetAll creates or updates multiple values
|
|
|
|
func (cache *Cache) SetAll(entries map[string]interface{}) {
|
|
|
|
for key, value := range entries {
|
|
|
|
cache.SetWithTTL(key, value, NoExpiration)
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// Get retrieves an entry using the key passed as parameter
|
|
|
|
// If there is no such entry, the value returned will be nil and the boolean will be false
|
|
|
|
// If there is an entry, the value returned will be the value cached and the boolean will be true
|
|
|
|
func (cache *Cache) Get(key string) (interface{}, bool) {
|
|
|
|
cache.mutex.Lock()
|
|
|
|
entry, ok := cache.get(key)
|
|
|
|
if !ok {
|
|
|
|
cache.mutex.Unlock()
|
|
|
|
cache.stats.Misses++
|
|
|
|
return nil, false
|
|
|
|
}
|
|
|
|
if entry.Expired() {
|
2021-01-13 03:08:18 +01:00
|
|
|
cache.stats.ExpiredKeys++
|
2020-12-30 07:08:20 +01:00
|
|
|
cache.delete(key)
|
|
|
|
cache.mutex.Unlock()
|
|
|
|
return nil, false
|
|
|
|
}
|
2021-01-13 03:08:18 +01:00
|
|
|
cache.stats.Hits++
|
2020-12-30 07:08:20 +01:00
|
|
|
if cache.evictionPolicy == LeastRecentlyUsed {
|
|
|
|
entry.Accessed()
|
|
|
|
if cache.head == entry {
|
|
|
|
cache.mutex.Unlock()
|
|
|
|
return entry.Value, true
|
|
|
|
}
|
|
|
|
// Because the eviction policy is LRU, we need to move the entry back to HEAD
|
|
|
|
cache.moveExistingEntryToHead(entry)
|
|
|
|
}
|
|
|
|
cache.mutex.Unlock()
|
|
|
|
return entry.Value, true
|
|
|
|
}
|
|
|
|
|
2021-01-13 03:08:18 +01:00
|
|
|
// GetByKeys retrieves multiple entries using the keys passed as parameter
|
|
|
|
// All keys are returned in the map, regardless of whether they exist or not, however, entries that do not exist in the
|
|
|
|
// cache will return nil, meaning that there is no way of determining whether a key genuinely has the value nil, or
|
|
|
|
// whether it doesn't exist in the cache using only this function.
|
|
|
|
func (cache *Cache) GetByKeys(keys []string) map[string]interface{} {
|
2020-12-30 07:08:20 +01:00
|
|
|
entries := make(map[string]interface{})
|
|
|
|
for _, key := range keys {
|
|
|
|
entries[key], _ = cache.Get(key)
|
|
|
|
}
|
|
|
|
return entries
|
|
|
|
}
|
|
|
|
|
2021-01-13 03:08:18 +01:00
|
|
|
// GetAll retrieves all cache entries
|
|
|
|
//
|
|
|
|
// If the eviction policy is LeastRecentlyUsed, note that unlike Get and GetByKeys, this does not update the last access
|
|
|
|
// timestamp. The reason for this is that since all cache entries will be accessed, updating the last access timestamp
|
|
|
|
// would provide very little benefit while harming the ability to accurately determine the next key that will be evicted
|
|
|
|
//
|
|
|
|
// You should probably avoid using this if you have a lot of entries.
|
|
|
|
//
|
|
|
|
// GetKeysByPattern is a good alternative if you want to retrieve entries that you do not have the key for, as it only
|
|
|
|
// retrieves the keys and does not trigger active eviction and has a parameter for setting a limit to the number of keys
|
|
|
|
// you wish to retrieve.
|
|
|
|
func (cache *Cache) GetAll() map[string]interface{} {
|
|
|
|
entries := make(map[string]interface{})
|
|
|
|
cache.mutex.Lock()
|
|
|
|
for key, entry := range cache.entries {
|
|
|
|
if entry.Expired() {
|
|
|
|
cache.delete(key)
|
|
|
|
continue
|
|
|
|
}
|
|
|
|
entries[key] = entry.Value
|
|
|
|
}
|
|
|
|
cache.stats.Hits += uint64(len(entries))
|
|
|
|
cache.mutex.Unlock()
|
|
|
|
return entries
|
|
|
|
}
|
|
|
|
|
2020-12-30 07:08:20 +01:00
|
|
|
// GetKeysByPattern retrieves a slice of keys that match a given pattern
|
|
|
|
// If the limit is set to 0, the entire cache will be searched for matching keys.
|
|
|
|
// If the limit is above 0, the search will stop once the specified number of matching keys have been found.
|
|
|
|
//
|
2021-01-13 03:08:18 +01:00
|
|
|
// e.g.
|
|
|
|
// cache.GetKeysByPattern("*some*", 0) will return all keys containing "some" in them
|
|
|
|
// cache.GetKeysByPattern("*some*", 5) will return 5 keys (or less) containing "some" in them
|
2020-12-30 07:08:20 +01:00
|
|
|
//
|
2021-01-13 03:08:18 +01:00
|
|
|
// Note that GetKeysByPattern does not trigger active evictions, nor does it count as accessing the entry, the latter
|
|
|
|
// only applying if the cache uses the LeastRecentlyUsed eviction policy.
|
|
|
|
// The reason for that behavior is that these two (active eviction and access) only applies when you access the value
|
|
|
|
// of the cache entry, and this function only returns the keys.
|
2020-12-30 07:08:20 +01:00
|
|
|
func (cache *Cache) GetKeysByPattern(pattern string, limit int) []string {
|
|
|
|
var matchingKeys []string
|
2021-01-13 03:08:18 +01:00
|
|
|
cache.mutex.Lock()
|
|
|
|
for key, value := range cache.entries {
|
|
|
|
if value.Expired() {
|
|
|
|
continue
|
|
|
|
}
|
2020-12-30 07:08:20 +01:00
|
|
|
if MatchPattern(pattern, key) {
|
|
|
|
matchingKeys = append(matchingKeys, key)
|
|
|
|
if limit > 0 && len(matchingKeys) >= limit {
|
|
|
|
break
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
2021-01-13 03:08:18 +01:00
|
|
|
cache.mutex.Unlock()
|
2020-12-30 07:08:20 +01:00
|
|
|
return matchingKeys
|
|
|
|
}
|
|
|
|
|
|
|
|
// Delete removes a key from the cache
|
|
|
|
//
|
|
|
|
// Returns false if the key did not exist.
|
|
|
|
func (cache *Cache) Delete(key string) bool {
|
|
|
|
cache.mutex.Lock()
|
|
|
|
ok := cache.delete(key)
|
|
|
|
cache.mutex.Unlock()
|
|
|
|
return ok
|
|
|
|
}
|
|
|
|
|
|
|
|
// DeleteAll deletes multiple entries based on the keys passed as parameter
|
|
|
|
//
|
|
|
|
// Returns the number of keys deleted
|
|
|
|
func (cache *Cache) DeleteAll(keys []string) int {
|
|
|
|
numberOfKeysDeleted := 0
|
|
|
|
cache.mutex.Lock()
|
|
|
|
for _, key := range keys {
|
|
|
|
if cache.delete(key) {
|
|
|
|
numberOfKeysDeleted++
|
|
|
|
}
|
|
|
|
}
|
|
|
|
cache.mutex.Unlock()
|
|
|
|
return numberOfKeysDeleted
|
|
|
|
}
|
|
|
|
|
|
|
|
// Count returns the total amount of entries in the cache, regardless of whether they're expired or not
|
|
|
|
func (cache *Cache) Count() int {
|
|
|
|
cache.mutex.RLock()
|
|
|
|
count := len(cache.entries)
|
|
|
|
cache.mutex.RUnlock()
|
|
|
|
return count
|
|
|
|
}
|
|
|
|
|
|
|
|
// Clear deletes all entries from the cache
|
|
|
|
func (cache *Cache) Clear() {
|
|
|
|
cache.mutex.Lock()
|
|
|
|
cache.entries = make(map[string]*Entry)
|
|
|
|
cache.memoryUsage = 0
|
|
|
|
cache.head = nil
|
|
|
|
cache.tail = nil
|
|
|
|
cache.mutex.Unlock()
|
|
|
|
}
|
|
|
|
|
|
|
|
// TTL returns the time until the cache entry specified by the key passed as parameter
|
|
|
|
// will be deleted.
|
|
|
|
func (cache *Cache) TTL(key string) (time.Duration, error) {
|
|
|
|
cache.mutex.RLock()
|
|
|
|
entry, ok := cache.get(key)
|
|
|
|
cache.mutex.RUnlock()
|
|
|
|
if !ok {
|
|
|
|
return 0, ErrKeyDoesNotExist
|
|
|
|
}
|
|
|
|
if entry.Expiration == NoExpiration {
|
|
|
|
return 0, ErrKeyHasNoExpiration
|
|
|
|
}
|
|
|
|
timeUntilExpiration := time.Until(time.Unix(0, entry.Expiration))
|
|
|
|
if timeUntilExpiration < 0 {
|
|
|
|
// The key has already expired but hasn't been deleted yet.
|
|
|
|
// From the client's perspective, this means that the cache entry doesn't exist
|
|
|
|
return 0, ErrKeyDoesNotExist
|
|
|
|
}
|
|
|
|
return timeUntilExpiration, nil
|
|
|
|
}
|
|
|
|
|
|
|
|
// Expire sets a key's expiration time
|
|
|
|
//
|
|
|
|
// A TTL of -1 means that the key will never expire
|
|
|
|
// A TTL of 0 means that the key will expire immediately
|
|
|
|
// If using LRU, note that this does not reset the position of the key
|
|
|
|
//
|
|
|
|
// Returns true if the cache key exists and has had its expiration time altered
|
|
|
|
func (cache *Cache) Expire(key string, ttl time.Duration) bool {
|
|
|
|
entry, ok := cache.get(key)
|
|
|
|
if !ok || entry.Expired() {
|
|
|
|
return false
|
|
|
|
}
|
|
|
|
if ttl != NoExpiration {
|
|
|
|
entry.Expiration = time.Now().Add(ttl).UnixNano()
|
|
|
|
} else {
|
|
|
|
entry.Expiration = NoExpiration
|
|
|
|
}
|
|
|
|
return true
|
|
|
|
}
|
|
|
|
|
|
|
|
// get retrieves an entry using the key passed as parameter, but unlike Get, it doesn't update the access time or
|
|
|
|
// move the position of the entry to the head
|
|
|
|
func (cache *Cache) get(key string) (*Entry, bool) {
|
|
|
|
entry, ok := cache.entries[key]
|
|
|
|
return entry, ok
|
|
|
|
}
|
|
|
|
|
|
|
|
func (cache *Cache) delete(key string) bool {
|
|
|
|
entry, ok := cache.entries[key]
|
|
|
|
if ok {
|
|
|
|
if cache.maxMemoryUsage != NoMaxMemoryUsage {
|
|
|
|
cache.memoryUsage -= entry.SizeInBytes()
|
|
|
|
}
|
|
|
|
cache.removeExistingEntryReferences(entry)
|
|
|
|
delete(cache.entries, key)
|
|
|
|
}
|
|
|
|
return ok
|
|
|
|
}
|
|
|
|
|
|
|
|
// moveExistingEntryToHead replaces the current cache head for an existing entry
|
|
|
|
func (cache *Cache) moveExistingEntryToHead(entry *Entry) {
|
|
|
|
if !(entry == cache.head && entry == cache.tail) {
|
|
|
|
cache.removeExistingEntryReferences(entry)
|
|
|
|
}
|
|
|
|
if entry != cache.head {
|
|
|
|
entry.previous = cache.head
|
|
|
|
entry.next = nil
|
|
|
|
if cache.head != nil {
|
|
|
|
cache.head.next = entry
|
|
|
|
}
|
|
|
|
cache.head = entry
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// removeExistingEntryReferences modifies the next and previous reference of an existing entry and re-links
|
|
|
|
// the next and previous entry accordingly, as well as the cache head or/and the cache tail if necessary.
|
|
|
|
// Note that it does not remove the entry from the cache, only the references.
|
|
|
|
func (cache *Cache) removeExistingEntryReferences(entry *Entry) {
|
|
|
|
if cache.tail == entry && cache.head == entry {
|
|
|
|
cache.tail = nil
|
|
|
|
cache.head = nil
|
|
|
|
} else if cache.tail == entry {
|
|
|
|
cache.tail = cache.tail.next
|
|
|
|
} else if cache.head == entry {
|
|
|
|
cache.head = cache.head.previous
|
|
|
|
}
|
|
|
|
if entry.previous != nil {
|
|
|
|
entry.previous.next = entry.next
|
|
|
|
}
|
|
|
|
if entry.next != nil {
|
|
|
|
entry.next.previous = entry.previous
|
|
|
|
}
|
|
|
|
entry.next = nil
|
|
|
|
entry.previous = nil
|
|
|
|
}
|
|
|
|
|
|
|
|
// evict removes the tail from the cache
|
|
|
|
func (cache *Cache) evict() {
|
|
|
|
if cache.tail == nil || len(cache.entries) == 0 {
|
|
|
|
return
|
|
|
|
}
|
|
|
|
if cache.tail != nil {
|
|
|
|
oldTail := cache.tail
|
|
|
|
cache.removeExistingEntryReferences(oldTail)
|
|
|
|
delete(cache.entries, oldTail.Key)
|
|
|
|
if cache.maxMemoryUsage != NoMaxMemoryUsage {
|
|
|
|
cache.memoryUsage -= oldTail.SizeInBytes()
|
|
|
|
}
|
|
|
|
cache.stats.EvictedKeys++
|
|
|
|
}
|
|
|
|
}
|