Documentation
¶
Overview ¶
Package memcache provides a client for the memcached cache server.
Index ¶
- Constants
- Variables
- type Client
- func (c *Client) Add(item *Item) error
- func (c *Client) Append(item *Item) error
- func (c *Client) Close() error
- func (c *Client) CompareAndSwap(item *Item) error
- func (c *Client) Decrement(key string, delta uint64) (newValue uint64, err error)
- func (c *Client) Delete(key string) error
- func (c *Client) DeleteAll() error
- func (c *Client) FlushAll() error
- func (c *Client) Get(key string) (item *Item, err error)
- func (c *Client) GetMulti(keys []string) (map[string]*Item, error)
- func (c *Client) Increment(key string, delta uint64) (newValue uint64, err error)
- func (c *Client) Ping() error
- func (c *Client) Prepend(item *Item) error
- func (c *Client) Replace(item *Item) error
- func (c *Client) Set(item *Item) error
- func (c *Client) Touch(key string, seconds int32) (err error)
- type ConnectTimeoutError
- type Item
- type ServerList
- type ServerSelector
Constants ¶
const ( // DefaultTimeout is the default socket read/write timeout. DefaultTimeout = 500 * time.Millisecond // DefaultMaxIdleConns is the default maximum number of idle connections // kept for any single address. DefaultMaxIdleConns = 2 )
Variables ¶
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 {
// DialContext connects to the address on the named network using the
// provided context.
//
// To connect to servers using TLS (memcached running with "--enable-ssl"),
// use a DialContext func that uses tls.Dialer.DialContext. See this
// package's tests as an example.
DialContext func(ctx context.Context, network, address string) (net.Conn, error)
// 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 ¶
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 ¶
Add writes the given item, if no value already exists for its key. ErrNotStored is returned if that condition is not met.
func (*Client) Append ¶
Append appends the given item to the existing item, if a value already exists for its key. ErrNotStored is returned if that condition is not met.
func (*Client) Close ¶
Close closes any open connections.
It returns the first error encountered closing connections, but always closes all connections.
After Close, the Client may still be used.
func (*Client) CompareAndSwap ¶
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 ¶
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 ¶
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) Get ¶
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 ¶
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 ¶
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 ¶
Ping checks all instances if they are alive. Returns error if any of them is down.
func (*Client) Prepend ¶
Prepend prepends the given item to the existing item, if a value already exists for its key. ErrNotStored is returned if that condition is not met.
func (*Client) Replace ¶
Replace writes the given item, but only if the server *does* already hold data for this key
func (*Client) Touch ¶
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 ¶
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
// CasID is the compare and swap ID.
//
// It's populated by get requests and then the same value is
// required for a CompareAndSwap request to succeed.
CasID uint64
}
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.
Source Files