README
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BigCache 
Fast, concurrent, evicting in-memory cache written to keep big number of entries without impact on performance. BigCache keeps entries on heap but omits GC for them. To achieve that operations on bytes arrays take place, therefore entries (de)serialization in front of the cache will be needed in most use cases.
Usage
Simple initialization
import "github.com/allegro/bigcache"
cache := bigcache.NewBigCache(bigcache.DefaultConfig(10 * time.Minute))
cache.Set("my-unique-key", []byte("value"))
entry, _ := cache.Get("my-unique-key")
fmt.Println(string(entry))
Custom initialization
When cache load can be predicted in advance then it is better to use custom initialization because additional memory allocation can be avoided in that way.
import "github.com/allegro/bigcache"
config := bigcache.Config{
Shards: 1000, // number of shards
LifeWindow: 10 * time.Minute, // time after which entry can be evicted
MaxEntriesInWindow: 1000 * 10 * 60, // rps * lifeWindow
MaxEntrySize: 500, // max entry size in bytes
Verbose: true, // prints information about additional memory allocation
}
cache := bigcache.NewBigCache(config)
cache.Set("my-unique-key", []byte("value"))
if entry, err := cache.Get("my-unique-key"); err == nil {
fmt.Println(string(entry))
}
How it works
BigCache relays on optimization presented in 1.5 version of Go (issue-9477).
This optimization states that if map without pointers in keys and values is used then GC will omit it’s content.
Therefore BigCache uses map[uint64]uint32 where keys are hashed and values are offsets of entries.
Entries are kept in bytes array, to omit GC again. Bytes array size can grow to gigabytes without impact on performance because GC will only see single pointer to it.
License
BigCache is released under the Apache 2.0 license (see LICENSE)
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
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Functions ¶
This section is empty.
Types ¶
type BigCache ¶
type BigCache struct {
// contains filtered or unexported fields
}
BigCache is fast, concurrent, evicting cache created to keep big number of entries without impact on performance. It keeps entries on heap but omits GC for them. To achieve that operations on bytes arrays take place, therefore entries (de)serialization in front of the cache will be needed in most use cases.
func NewBigCache ¶
NewBigCache initialize new instance of BigCache
type Config ¶
type Config struct {
// Number of cache shards
Shards int
// Time after which entry can be evicted
LifeWindow time.Duration
// Max number of entries in life window. Used to allocate proper size of cache in every shard.
// When proper value is set then cache will not allocate additional memory
MaxEntriesInWindow int
// Max size of entry in bytes. Used to allocate proper size of cache in every shard.
MaxEntrySize int
// Verbose mode prints information about new memory allocation
Verbose bool
}
Config for BigCache
func DefaultConfig ¶
DefaultConfig initializes config with default values. When load for BigCache can be predicted in advance then it is better to use custom config.
type EntryNotFoundError ¶
type EntryNotFoundError struct {
// contains filtered or unexported fields
}
EntryNotFoundError is an error type struct which is returned when entry was not found for provided key
func (EntryNotFoundError) Error ¶
func (e EntryNotFoundError) Error() string
Error returned when entry does not exist.
Source Files
Directories