cache

package
v0.4.7 Latest Latest
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 Go to latest Published: Oct 23, 2019 License: Apache-2.0 Imports: 23 Imported by: 0

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Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func HashKey 

func HashKey(key string) string

HashKey hashes key into something you can store in memcached.

Types

type BackgroundConfig 

type BackgroundConfig struct {
	WriteBackGoroutines int `yaml:"writeback_goroutines,omitempty"`
	WriteBackBuffer     int `yaml:"writeback_buffer,omitempty"`
}

BackgroundConfig is config for a Background Cache.

func (*BackgroundConfig) RegisterFlagsWithPrefix 

func (cfg *BackgroundConfig) RegisterFlagsWithPrefix(prefix string, description string, f *flag.FlagSet)

RegisterFlagsWithPrefix adds the flags required to config this to the given FlagSet

type Cache 

type Cache interface {
	Store(ctx context.Context, key []string, buf [][]byte)
	Fetch(ctx context.Context, keys []string) (found []string, bufs [][]byte, missing []string)
	Stop() error
}

Cache byte arrays by key.

NB we intentionally do not return errors in this interface - caching is best effort by definition. We found that when these methods did return errors, the caller would just log them - so its easier for implementation to do that. Whatsmore, we found partially successful Fetchs were often treated as failed when they returned an error.

func Instrument 

func Instrument(name string, cache Cache) Cache

Instrument returns an instrumented cache.

func New 

func New(cfg Config) (Cache, error)

New creates a new Cache using Config.

func NewBackground 

func NewBackground(name string, cfg BackgroundConfig, cache Cache) Cache

NewBackground returns a new Cache that does stores on background goroutines.

func NewMockCache 

func NewMockCache() Cache

NewMockCache makes a new MockCache

func NewSnappy 

func NewSnappy(next Cache) Cache

NewSnappy makes a new snappy encoding cache wrapper.

func NewTiered 

func NewTiered(caches []Cache) Cache

NewTiered makes a new tiered cache.

func StopOnce 

func StopOnce(cache Cache) Cache

StopOnce wraps a Cache and ensures its only stopped once.

type Config 

type Config struct {
	EnableFifoCache bool `yaml:"enable_fifocache,omitempty"`

	DefaultValidity time.Duration `yaml:"defaul_validity,omitempty"`

	Background     BackgroundConfig      `yaml:"background,omitempty"`
	Memcache       MemcachedConfig       `yaml:"memcached,omitempty"`
	MemcacheClient MemcachedClientConfig `yaml:"memcached_client,omitempty"`
	Redis          RedisConfig           `yaml:"redis,omitempty"`
	Fifocache      FifoCacheConfig       `yaml:"fifocache,omitempty"`

	// This is to name the cache metrics properly.
	Prefix string `yaml:"prefix,omitempty"`

	// For tests to inject specific implementations.
	Cache Cache
}

Config for building Caches.

func (*Config) RegisterFlagsWithPrefix 

func (cfg *Config) RegisterFlagsWithPrefix(prefix string, description string, f *flag.FlagSet)

RegisterFlagsWithPrefix adds the flags required to config this to the given FlagSet

type FifoCache 

type FifoCache struct {
	// contains filtered or unexported fields
}

FifoCache is a simple string -> interface{} cache which uses a fifo slide to manage evictions. O(1) inserts and updates, O(1) gets.

func NewFifoCache 

func NewFifoCache(name string, cfg FifoCacheConfig) *FifoCache

NewFifoCache returns a new initialised FifoCache of size. TODO(bwplotka): Fix metrics, get them out of globals, separate or allow prefixing.

func (*FifoCache) Fetch 

func (c *FifoCache) Fetch(ctx context.Context, keys []string) (found []string, bufs [][]byte, missing []string)

Fetch implements Cache.

func (*FifoCache) Get 

func (c *FifoCache) Get(ctx context.Context, key string) (interface{}, bool)

Get returns the stored value against the key and when the key was last updated.

func (*FifoCache) Put 

func (c *FifoCache) Put(ctx context.Context, keys []string, values []interface{})

Put stores the value against the key.

func (*FifoCache) Stop 

func (c *FifoCache) Stop() error

Stop implements Cache.

func (*FifoCache) Store 

func (c *FifoCache) Store(ctx context.Context, keys []string, bufs [][]byte)

Store implements Cache.

type FifoCacheConfig 

type FifoCacheConfig struct {
	Size     int           `yaml:"size,omitempty"`
	Validity time.Duration `yaml:"validity,omitempty"`
}

FifoCacheConfig holds config for the FifoCache.

func (*FifoCacheConfig) RegisterFlagsWithPrefix 

func (cfg *FifoCacheConfig) RegisterFlagsWithPrefix(prefix, description string, f *flag.FlagSet)

RegisterFlagsWithPrefix adds the flags required to config this to the given FlagSet

type Memcached 

type Memcached struct {
	// contains filtered or unexported fields
}

Memcached type caches chunks in memcached

func NewMemcached 

func NewMemcached(cfg MemcachedConfig, client MemcachedClient, name string) *Memcached

NewMemcached makes a new Memcache. TODO(bwplotka): Fix metrics, get them out of globals, separate or allow prefixing. TODO(bwplotka): Remove globals & util packages from cache package entirely (e.g util.Logger).

func (*Memcached) Fetch 

func (c *Memcached) Fetch(ctx context.Context, keys []string) (found []string, bufs [][]byte, missed []string)

Fetch gets keys from the cache. The keys that are found must be in the order of the keys requested.

func (*Memcached) Stop 

func (c *Memcached) Stop() error

Stop does nothing.

func (*Memcached) Store 

func (c *Memcached) Store(ctx context.Context, keys []string, bufs [][]byte)

Store stores the key in the cache.

type MemcachedClient 

type MemcachedClient interface {
	GetMulti(keys []string) (map[string]*memcache.Item, error)
	Set(item *memcache.Item) error
}

MemcachedClient interface exists for mocking memcacheClient.

func NewMemcachedClient 

func NewMemcachedClient(cfg MemcachedClientConfig) MemcachedClient

NewMemcachedClient creates a new MemcacheClient that gets its server list from SRV and updates the server list on a regular basis.

type MemcachedClientConfig 

type MemcachedClientConfig struct {
	Host           string        `yaml:"host,omitempty"`
	Service        string        `yaml:"service,omitempty"`
	Timeout        time.Duration `yaml:"timeout,omitempty"`
	MaxIdleConns   int           `yaml:"max_idle_conns,omitempty"`
	UpdateInterval time.Duration `yaml:"update_interval,omitempty"`
	ConsistentHash bool          `yaml:"consistent_hash,omitempty"`
}

MemcachedClientConfig defines how a MemcachedClient should be constructed.

func (*MemcachedClientConfig) RegisterFlagsWithPrefix 

func (cfg *MemcachedClientConfig) RegisterFlagsWithPrefix(prefix, description string, f *flag.FlagSet)

RegisterFlagsWithPrefix adds the flags required to config this to the given FlagSet

type MemcachedConfig 

type MemcachedConfig struct {
	Expiration time.Duration `yaml:"expiration,omitempty"`

	BatchSize   int `yaml:"batch_size,omitempty"`
	Parallelism int `yaml:"parallelism,omitempty"`
}

MemcachedConfig is config to make a Memcached

func (*MemcachedConfig) RegisterFlagsWithPrefix 

func (cfg *MemcachedConfig) RegisterFlagsWithPrefix(prefix, description string, f *flag.FlagSet)

RegisterFlagsWithPrefix adds the flags required to config this to the given FlagSet

type MemcachedJumpHashSelector 

type MemcachedJumpHashSelector struct {
	// contains filtered or unexported fields
}

MemcachedJumpHashSelector implements the memcache.ServerSelector interface. MemcachedJumpHashSelector utilizes a jump hash to distribute keys to servers.

While adding or removing servers only requires 1/N keys to move, servers are treated as a stack and can only be pushed/popped. Therefore, MemcachedJumpHashSelector works best for servers with consistent DNS names where the naturally sorted order is predictable.

func (*MemcachedJumpHashSelector) Each 

func (s *MemcachedJumpHashSelector) Each(f func(net.Addr) error) error

Each iterates over each server and calls the given function. If f returns a non-nil error, iteration will stop and that error will be returned.

func (*MemcachedJumpHashSelector) PickServer 

func (s *MemcachedJumpHashSelector) PickServer(key string) (net.Addr, error)

PickServer returns the server address that a given item should be shared onto.

func (*MemcachedJumpHashSelector) SetServers 

func (s *MemcachedJumpHashSelector) SetServers(servers ...string) error

SetServers changes a MemcachedJumpHashSelector's set of servers at runtime and is safe for concurrent use by multiple goroutines.

Each server is given equal weight. A server is given more weight if it's listed multiple times.

SetServers returns an error if any of the server names fail to resolve. No attempt is made to connect to the server. If any error occurs, no changes are made to the internal server list.

To minimize the number of rehashes for keys when scaling the number of servers in subsequent calls to SetServers, servers are stored in natural sort order.

type RedisCache added in v0.4.0 

type RedisCache struct {
	// contains filtered or unexported fields
}

RedisCache type caches chunks in redis

func NewRedisCache added in v0.4.0 

func NewRedisCache(cfg RedisConfig, name string, pool *redis.Pool) *RedisCache

NewRedisCache creates a new RedisCache

func (*RedisCache) Fetch added in v0.4.0 

func (c *RedisCache) Fetch(ctx context.Context, keys []string) (found []string, bufs [][]byte, missed []string)

Fetch gets keys from the cache. The keys that are found must be in the order of the keys requested.

func (*RedisCache) Stop added in v0.4.0 

func (c *RedisCache) Stop() error

Stop stops the redis client.

func (*RedisCache) Store added in v0.4.0 

func (c *RedisCache) Store(ctx context.Context, keys []string, bufs [][]byte)

Store stores the key in the cache.

type RedisConfig added in v0.4.0 

type RedisConfig struct {
	Endpoint       string        `yaml:"endpoint,omitempty"`
	Timeout        time.Duration `yaml:"timeout,omitempty"`
	Expiration     time.Duration `yaml:"expiration,omitempty"`
	MaxIdleConns   int           `yaml:"max_idle_conns,omitempty"`
	MaxActiveConns int           `yaml:"max_active_conns,omitempty"`
}

RedisConfig defines how a RedisCache should be constructed.

func (*RedisConfig) RegisterFlagsWithPrefix added in v0.4.0 

func (cfg *RedisConfig) RegisterFlagsWithPrefix(prefix, description string, f *flag.FlagSet)

RegisterFlagsWithPrefix adds the flags required to config this to the given FlagSet

Source Files

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