Documentation

Overview

    Package memcache provides a client for the memcached cache server.

    Index

    Constants

    View Source
    const (
    	// DefaultTimeout is the default socket read/write timeout.
    	DefaultTimeout = 100 * time.Millisecond
    
    	// DefaultMaxIdleConns is the default maximum number of idle connections
    	// kept for any single address.
    	DefaultMaxIdleConns = 2
    )

    Variables

    View Source
    var (
    	// ErrCacheMiss means that a Get failed because the item wasn't present.
    	ErrCacheMiss = errors.New("memcache: cache miss")
    
    	// ErrCASConflict means that a CompareAndSwap call failed due to the
    	// cached value being modified between the Get and the CompareAndSwap.
    	// If the cached value was simply evicted rather than replaced,
    	// ErrNotStored will be returned instead.
    	ErrCASConflict = errors.New("memcache: compare-and-swap conflict")
    
    	// ErrNotStored means that a conditional write operation (i.e. Add or
    	// CompareAndSwap) failed because the condition was not satisfied.
    	ErrNotStored = errors.New("memcache: item not stored")
    
    	// ErrServer means that a server error occurred.
    	ErrServerError = errors.New("memcache: server error")
    
    	// ErrNoStats means that no statistics were available.
    	ErrNoStats = errors.New("memcache: no statistics available")
    
    	// ErrMalformedKey is returned when an invalid key is used.
    	// Keys must be at maximum 250 bytes long and not
    	// contain whitespace or control characters.
    	ErrMalformedKey = errors.New("malformed: key is too long or contains invalid characters")
    
    	// ErrNoServers is returned when no servers are configured or available.
    	ErrNoServers = errors.New("memcache: no servers configured or available")
    )

    Functions

    This section is empty.

    Types

    type Client

    type Client struct {
    	// Timeout specifies the socket read/write timeout.
    	// If zero, DefaultTimeout is used.
    	Timeout time.Duration
    
    	// MaxIdleConns specifies the maximum number of idle connections that will
    	// be maintained per address. If less than one, DefaultMaxIdleConns will be
    	// used.
    	//
    	// Consider your expected traffic rates and latency carefully. This should
    	// be set to a number higher than your peak parallel requests.
    	MaxIdleConns int
    	// contains filtered or unexported fields
    }

      Client is a memcache client. It is safe for unlocked use by multiple concurrent goroutines.

      func New

      func New(server ...string) *Client

        New returns a memcache client using the provided server(s) with equal weight. If a server is listed multiple times, it gets a proportional amount of weight.

        func NewFromSelector

        func NewFromSelector(ss ServerSelector) *Client

          NewFromSelector returns a new Client using the provided ServerSelector.

          func (*Client) Add

          func (c *Client) Add(item *Item) error

            Add writes the given item, if no value already exists for its key. ErrNotStored is returned if that condition is not met.

            func (*Client) CompareAndSwap

            func (c *Client) CompareAndSwap(item *Item) error

              CompareAndSwap writes the given item that was previously returned by Get, if the value was neither modified or evicted between the Get and the CompareAndSwap calls. The item's Key should not change between calls but all other item fields may differ. ErrCASConflict is returned if the value was modified in between the calls. ErrNotStored is returned if the value was evicted in between the calls.

              func (*Client) Decrement

              func (c *Client) Decrement(key string, delta uint64) (newValue uint64, err error)

                Decrement atomically decrements key by delta. The return value is the new value after being decremented or an error. If the value didn't exist in memcached the error is ErrCacheMiss. The value in memcached must be an decimal number, or an error will be returned. On underflow, the new value is capped at zero and does not wrap around.

                func (*Client) Delete

                func (c *Client) Delete(key string) error

                  Delete deletes the item with the provided key. The error ErrCacheMiss is returned if the item didn't already exist in the cache.

                  func (*Client) DeleteAll

                  func (c *Client) DeleteAll() error

                    DeleteAll deletes all items in the cache.

                    func (*Client) FlushAll

                    func (c *Client) FlushAll() error

                    func (*Client) Get

                    func (c *Client) Get(key string) (item *Item, err error)

                      Get gets the item for the given key. ErrCacheMiss is returned for a memcache cache miss. The key must be at most 250 bytes in length.

                      func (*Client) GetMulti

                      func (c *Client) GetMulti(keys []string) (map[string]*Item, error)

                        GetMulti is a batch version of Get. The returned map from keys to items may have fewer elements than the input slice, due to memcache cache misses. Each key must be at most 250 bytes in length. If no error is returned, the returned map will also be non-nil.

                        func (*Client) Increment

                        func (c *Client) Increment(key string, delta uint64) (newValue uint64, err error)

                          Increment atomically increments key by delta. The return value is the new value after being incremented or an error. If the value didn't exist in memcached the error is ErrCacheMiss. The value in memcached must be an decimal number, or an error will be returned. On 64-bit overflow, the new value wraps around.

                          func (*Client) Ping

                          func (c *Client) Ping() error

                            Ping checks all instances if they are alive. Returns error if any of them is down.

                            func (*Client) Replace

                            func (c *Client) Replace(item *Item) error

                              Replace writes the given item, but only if the server *does* already hold data for this key

                              func (*Client) Set

                              func (c *Client) Set(item *Item) error

                                Set writes the given item, unconditionally.

                                func (*Client) Touch

                                func (c *Client) Touch(key string, seconds int32) (err error)

                                  Touch updates the expiry for the given key. The seconds parameter is either a Unix timestamp or, if seconds is less than 1 month, the number of seconds into the future at which time the item will expire. Zero means the item has no expiration time. ErrCacheMiss is returned if the key is not in the cache. The key must be at most 250 bytes in length.

                                  type ConnectTimeoutError

                                  type ConnectTimeoutError struct {
                                  	Addr net.Addr
                                  }

                                    ConnectTimeoutError is the error type used when it takes too long to connect to the desired host. This level of detail can generally be ignored.

                                    func (*ConnectTimeoutError) Error

                                    func (cte *ConnectTimeoutError) Error() string

                                    type Item

                                    type Item struct {
                                    	// Key is the Item's key (250 bytes maximum).
                                    	Key string
                                    
                                    	// Value is the Item's value.
                                    	Value []byte
                                    
                                    	// Flags are server-opaque flags whose semantics are entirely
                                    	// up to the app.
                                    	Flags uint32
                                    
                                    	// Expiration is the cache expiration time, in seconds: either a relative
                                    	// time from now (up to 1 month), or an absolute Unix epoch time.
                                    	// Zero means the Item has no expiration time.
                                    	Expiration int32
                                    	// contains filtered or unexported fields
                                    }

                                      Item is an item to be got or stored in a memcached server.

                                      type ServerList

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

                                        ServerList is a simple ServerSelector. Its zero value is usable.

                                        func (*ServerList) Each

                                        func (ss *ServerList) Each(f func(net.Addr) error) error

                                          Each iterates over each server calling the given function

                                          func (*ServerList) PickServer

                                          func (ss *ServerList) PickServer(key string) (net.Addr, error)

                                          func (*ServerList) SetServers

                                          func (ss *ServerList) SetServers(servers ...string) error

                                            SetServers changes a ServerList'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 is returned, no changes are made to the ServerList.

                                            type ServerSelector

                                            type ServerSelector interface {
                                            	// PickServer returns the server address that a given item
                                            	// should be shared onto.
                                            	PickServer(key string) (net.Addr, error)
                                            	Each(func(net.Addr) error) error
                                            }

                                              ServerSelector is the interface that selects a memcache server as a function of the item's key.

                                              All ServerSelector implementations must be safe for concurrent use by multiple goroutines.