mirror of
https://github.com/go-gitea/gitea.git
synced 2024-10-31 08:37:35 -04:00
171b359877
Signed-off-by: Tamal Saha <tamal@appscode.com>
688 lines
19 KiB
Go
Vendored
688 lines
19 KiB
Go
Vendored
/*
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Copyright 2011 Google Inc.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// Package memcache provides a client for the memcached cache server.
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package memcache
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import (
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"bufio"
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"bytes"
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"errors"
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"fmt"
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"io"
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"net"
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"strconv"
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"strings"
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"sync"
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"time"
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)
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// Similar to:
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// https://godoc.org/google.golang.org/appengine/memcache
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var (
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// ErrCacheMiss means that a Get failed because the item wasn't present.
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ErrCacheMiss = errors.New("memcache: cache miss")
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// ErrCASConflict means that a CompareAndSwap call failed due to the
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// cached value being modified between the Get and the CompareAndSwap.
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// If the cached value was simply evicted rather than replaced,
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// ErrNotStored will be returned instead.
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ErrCASConflict = errors.New("memcache: compare-and-swap conflict")
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// ErrNotStored means that a conditional write operation (i.e. Add or
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// CompareAndSwap) failed because the condition was not satisfied.
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ErrNotStored = errors.New("memcache: item not stored")
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// ErrServer means that a server error occurred.
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ErrServerError = errors.New("memcache: server error")
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// ErrNoStats means that no statistics were available.
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ErrNoStats = errors.New("memcache: no statistics available")
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// ErrMalformedKey is returned when an invalid key is used.
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// Keys must be at maximum 250 bytes long and not
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// contain whitespace or control characters.
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ErrMalformedKey = errors.New("malformed: key is too long or contains invalid characters")
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// ErrNoServers is returned when no servers are configured or available.
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ErrNoServers = errors.New("memcache: no servers configured or available")
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)
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const (
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// DefaultTimeout is the default socket read/write timeout.
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DefaultTimeout = 100 * time.Millisecond
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// DefaultMaxIdleConns is the default maximum number of idle connections
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// kept for any single address.
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DefaultMaxIdleConns = 2
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)
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const buffered = 8 // arbitrary buffered channel size, for readability
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// resumableError returns true if err is only a protocol-level cache error.
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// This is used to determine whether or not a server connection should
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// be re-used or not. If an error occurs, by default we don't reuse the
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// connection, unless it was just a cache error.
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func resumableError(err error) bool {
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switch err {
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case ErrCacheMiss, ErrCASConflict, ErrNotStored, ErrMalformedKey:
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return true
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}
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return false
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}
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func legalKey(key string) bool {
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if len(key) > 250 {
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return false
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}
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for i := 0; i < len(key); i++ {
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if key[i] <= ' ' || key[i] == 0x7f {
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return false
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}
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}
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return true
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}
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var (
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crlf = []byte("\r\n")
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space = []byte(" ")
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resultOK = []byte("OK\r\n")
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resultStored = []byte("STORED\r\n")
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resultNotStored = []byte("NOT_STORED\r\n")
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resultExists = []byte("EXISTS\r\n")
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resultNotFound = []byte("NOT_FOUND\r\n")
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resultDeleted = []byte("DELETED\r\n")
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resultEnd = []byte("END\r\n")
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resultOk = []byte("OK\r\n")
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resultTouched = []byte("TOUCHED\r\n")
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resultClientErrorPrefix = []byte("CLIENT_ERROR ")
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)
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// New returns a memcache client using the provided server(s)
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// with equal weight. If a server is listed multiple times,
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// it gets a proportional amount of weight.
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func New(server ...string) *Client {
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ss := new(ServerList)
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ss.SetServers(server...)
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return NewFromSelector(ss)
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}
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// NewFromSelector returns a new Client using the provided ServerSelector.
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func NewFromSelector(ss ServerSelector) *Client {
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return &Client{selector: ss}
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}
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// Client is a memcache client.
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// It is safe for unlocked use by multiple concurrent goroutines.
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type Client struct {
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// Timeout specifies the socket read/write timeout.
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// If zero, DefaultTimeout is used.
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Timeout time.Duration
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// MaxIdleConns specifies the maximum number of idle connections that will
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// be maintained per address. If less than one, DefaultMaxIdleConns will be
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// used.
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//
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// Consider your expected traffic rates and latency carefully. This should
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// be set to a number higher than your peak parallel requests.
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MaxIdleConns int
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selector ServerSelector
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lk sync.Mutex
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freeconn map[string][]*conn
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}
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// Item is an item to be got or stored in a memcached server.
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type Item struct {
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// Key is the Item's key (250 bytes maximum).
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Key string
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// Value is the Item's value.
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Value []byte
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// Flags are server-opaque flags whose semantics are entirely
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// up to the app.
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Flags uint32
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// Expiration is the cache expiration time, in seconds: either a relative
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// time from now (up to 1 month), or an absolute Unix epoch time.
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// Zero means the Item has no expiration time.
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Expiration int32
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// Compare and swap ID.
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casid uint64
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}
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// conn is a connection to a server.
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type conn struct {
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nc net.Conn
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rw *bufio.ReadWriter
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addr net.Addr
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c *Client
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}
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// release returns this connection back to the client's free pool
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func (cn *conn) release() {
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cn.c.putFreeConn(cn.addr, cn)
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}
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func (cn *conn) extendDeadline() {
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cn.nc.SetDeadline(time.Now().Add(cn.c.netTimeout()))
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}
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// condRelease releases this connection if the error pointed to by err
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// is nil (not an error) or is only a protocol level error (e.g. a
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// cache miss). The purpose is to not recycle TCP connections that
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// are bad.
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func (cn *conn) condRelease(err *error) {
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if *err == nil || resumableError(*err) {
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cn.release()
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} else {
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cn.nc.Close()
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}
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}
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func (c *Client) putFreeConn(addr net.Addr, cn *conn) {
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c.lk.Lock()
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defer c.lk.Unlock()
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if c.freeconn == nil {
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c.freeconn = make(map[string][]*conn)
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}
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freelist := c.freeconn[addr.String()]
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if len(freelist) >= c.maxIdleConns() {
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cn.nc.Close()
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return
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}
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c.freeconn[addr.String()] = append(freelist, cn)
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}
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func (c *Client) getFreeConn(addr net.Addr) (cn *conn, ok bool) {
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c.lk.Lock()
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defer c.lk.Unlock()
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if c.freeconn == nil {
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return nil, false
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}
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freelist, ok := c.freeconn[addr.String()]
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if !ok || len(freelist) == 0 {
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return nil, false
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}
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cn = freelist[len(freelist)-1]
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c.freeconn[addr.String()] = freelist[:len(freelist)-1]
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return cn, true
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}
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func (c *Client) netTimeout() time.Duration {
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if c.Timeout != 0 {
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return c.Timeout
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}
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return DefaultTimeout
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}
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func (c *Client) maxIdleConns() int {
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if c.MaxIdleConns > 0 {
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return c.MaxIdleConns
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}
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return DefaultMaxIdleConns
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}
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// ConnectTimeoutError is the error type used when it takes
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// too long to connect to the desired host. This level of
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// detail can generally be ignored.
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type ConnectTimeoutError struct {
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Addr net.Addr
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}
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func (cte *ConnectTimeoutError) Error() string {
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return "memcache: connect timeout to " + cte.Addr.String()
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}
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func (c *Client) dial(addr net.Addr) (net.Conn, error) {
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type connError struct {
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cn net.Conn
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err error
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}
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nc, err := net.DialTimeout(addr.Network(), addr.String(), c.netTimeout())
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if err == nil {
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return nc, nil
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}
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if ne, ok := err.(net.Error); ok && ne.Timeout() {
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return nil, &ConnectTimeoutError{addr}
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}
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return nil, err
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}
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func (c *Client) getConn(addr net.Addr) (*conn, error) {
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cn, ok := c.getFreeConn(addr)
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if ok {
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cn.extendDeadline()
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return cn, nil
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}
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nc, err := c.dial(addr)
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if err != nil {
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return nil, err
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}
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cn = &conn{
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nc: nc,
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addr: addr,
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rw: bufio.NewReadWriter(bufio.NewReader(nc), bufio.NewWriter(nc)),
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c: c,
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}
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cn.extendDeadline()
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return cn, nil
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}
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func (c *Client) onItem(item *Item, fn func(*Client, *bufio.ReadWriter, *Item) error) error {
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addr, err := c.selector.PickServer(item.Key)
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if err != nil {
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return err
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}
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cn, err := c.getConn(addr)
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if err != nil {
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return err
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}
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defer cn.condRelease(&err)
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if err = fn(c, cn.rw, item); err != nil {
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return err
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}
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return nil
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}
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func (c *Client) FlushAll() error {
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return c.selector.Each(c.flushAllFromAddr)
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}
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// Get gets the item for the given key. ErrCacheMiss is returned for a
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// memcache cache miss. The key must be at most 250 bytes in length.
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func (c *Client) Get(key string) (item *Item, err error) {
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err = c.withKeyAddr(key, func(addr net.Addr) error {
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return c.getFromAddr(addr, []string{key}, func(it *Item) { item = it })
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})
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if err == nil && item == nil {
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err = ErrCacheMiss
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}
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return
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}
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// Touch updates the expiry for the given key. The seconds parameter is either
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// a Unix timestamp or, if seconds is less than 1 month, the number of seconds
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// into the future at which time the item will expire. Zero means the item has
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// no expiration time. ErrCacheMiss is returned if the key is not in the cache.
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// The key must be at most 250 bytes in length.
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func (c *Client) Touch(key string, seconds int32) (err error) {
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return c.withKeyAddr(key, func(addr net.Addr) error {
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return c.touchFromAddr(addr, []string{key}, seconds)
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})
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}
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func (c *Client) withKeyAddr(key string, fn func(net.Addr) error) (err error) {
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if !legalKey(key) {
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return ErrMalformedKey
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}
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addr, err := c.selector.PickServer(key)
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if err != nil {
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return err
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}
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return fn(addr)
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}
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func (c *Client) withAddrRw(addr net.Addr, fn func(*bufio.ReadWriter) error) (err error) {
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cn, err := c.getConn(addr)
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if err != nil {
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return err
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}
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defer cn.condRelease(&err)
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return fn(cn.rw)
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}
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func (c *Client) withKeyRw(key string, fn func(*bufio.ReadWriter) error) error {
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return c.withKeyAddr(key, func(addr net.Addr) error {
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return c.withAddrRw(addr, fn)
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})
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}
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func (c *Client) getFromAddr(addr net.Addr, keys []string, cb func(*Item)) error {
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return c.withAddrRw(addr, func(rw *bufio.ReadWriter) error {
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if _, err := fmt.Fprintf(rw, "gets %s\r\n", strings.Join(keys, " ")); err != nil {
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return err
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}
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if err := rw.Flush(); err != nil {
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return err
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}
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if err := parseGetResponse(rw.Reader, cb); err != nil {
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return err
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}
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return nil
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})
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}
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// flushAllFromAddr send the flush_all command to the given addr
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func (c *Client) flushAllFromAddr(addr net.Addr) error {
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return c.withAddrRw(addr, func(rw *bufio.ReadWriter) error {
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if _, err := fmt.Fprintf(rw, "flush_all\r\n"); err != nil {
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return err
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}
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if err := rw.Flush(); err != nil {
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return err
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}
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line, err := rw.ReadSlice('\n')
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if err != nil {
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return err
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}
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switch {
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case bytes.Equal(line, resultOk):
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break
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default:
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return fmt.Errorf("memcache: unexpected response line from flush_all: %q", string(line))
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}
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return nil
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})
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}
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func (c *Client) touchFromAddr(addr net.Addr, keys []string, expiration int32) error {
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return c.withAddrRw(addr, func(rw *bufio.ReadWriter) error {
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for _, key := range keys {
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if _, err := fmt.Fprintf(rw, "touch %s %d\r\n", key, expiration); err != nil {
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return err
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}
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if err := rw.Flush(); err != nil {
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return err
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}
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line, err := rw.ReadSlice('\n')
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if err != nil {
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return err
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}
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switch {
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case bytes.Equal(line, resultTouched):
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break
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case bytes.Equal(line, resultNotFound):
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return ErrCacheMiss
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default:
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return fmt.Errorf("memcache: unexpected response line from touch: %q", string(line))
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}
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}
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return nil
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})
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}
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// GetMulti is a batch version of Get. The returned map from keys to
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// items may have fewer elements than the input slice, due to memcache
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// cache misses. Each key must be at most 250 bytes in length.
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// If no error is returned, the returned map will also be non-nil.
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func (c *Client) GetMulti(keys []string) (map[string]*Item, error) {
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var lk sync.Mutex
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m := make(map[string]*Item)
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addItemToMap := func(it *Item) {
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lk.Lock()
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defer lk.Unlock()
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m[it.Key] = it
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}
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keyMap := make(map[net.Addr][]string)
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for _, key := range keys {
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if !legalKey(key) {
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return nil, ErrMalformedKey
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}
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addr, err := c.selector.PickServer(key)
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if err != nil {
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return nil, err
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}
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keyMap[addr] = append(keyMap[addr], key)
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}
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ch := make(chan error, buffered)
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for addr, keys := range keyMap {
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go func(addr net.Addr, keys []string) {
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ch <- c.getFromAddr(addr, keys, addItemToMap)
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}(addr, keys)
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}
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var err error
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for _ = range keyMap {
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if ge := <-ch; ge != nil {
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err = ge
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}
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}
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return m, err
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}
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// parseGetResponse reads a GET response from r and calls cb for each
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// read and allocated Item
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func parseGetResponse(r *bufio.Reader, cb func(*Item)) error {
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for {
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line, err := r.ReadSlice('\n')
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if err != nil {
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return err
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}
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if bytes.Equal(line, resultEnd) {
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return nil
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}
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it := new(Item)
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size, err := scanGetResponseLine(line, it)
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if err != nil {
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return err
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}
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it.Value = make([]byte, size+2)
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_, err = io.ReadFull(r, it.Value)
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if err != nil {
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it.Value = nil
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return err
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}
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if !bytes.HasSuffix(it.Value, crlf) {
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it.Value = nil
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return fmt.Errorf("memcache: corrupt get result read")
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}
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it.Value = it.Value[:size]
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cb(it)
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}
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}
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// scanGetResponseLine populates it and returns the declared size of the item.
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// It does not read the bytes of the item.
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func scanGetResponseLine(line []byte, it *Item) (size int, err error) {
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pattern := "VALUE %s %d %d %d\r\n"
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dest := []interface{}{&it.Key, &it.Flags, &size, &it.casid}
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if bytes.Count(line, space) == 3 {
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pattern = "VALUE %s %d %d\r\n"
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dest = dest[:3]
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}
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n, err := fmt.Sscanf(string(line), pattern, dest...)
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if err != nil || n != len(dest) {
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return -1, fmt.Errorf("memcache: unexpected line in get response: %q", line)
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}
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return size, nil
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}
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// Set writes the given item, unconditionally.
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func (c *Client) Set(item *Item) error {
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return c.onItem(item, (*Client).set)
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}
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func (c *Client) set(rw *bufio.ReadWriter, item *Item) error {
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return c.populateOne(rw, "set", item)
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}
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// Add writes the given item, if no value already exists for its
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// key. ErrNotStored is returned if that condition is not met.
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func (c *Client) Add(item *Item) error {
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return c.onItem(item, (*Client).add)
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}
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func (c *Client) add(rw *bufio.ReadWriter, item *Item) error {
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return c.populateOne(rw, "add", item)
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}
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// Replace writes the given item, but only if the server *does*
|
|
// already hold data for this key
|
|
func (c *Client) Replace(item *Item) error {
|
|
return c.onItem(item, (*Client).replace)
|
|
}
|
|
|
|
func (c *Client) replace(rw *bufio.ReadWriter, item *Item) error {
|
|
return c.populateOne(rw, "replace", item)
|
|
}
|
|
|
|
// 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 (c *Client) CompareAndSwap(item *Item) error {
|
|
return c.onItem(item, (*Client).cas)
|
|
}
|
|
|
|
func (c *Client) cas(rw *bufio.ReadWriter, item *Item) error {
|
|
return c.populateOne(rw, "cas", item)
|
|
}
|
|
|
|
func (c *Client) populateOne(rw *bufio.ReadWriter, verb string, item *Item) error {
|
|
if !legalKey(item.Key) {
|
|
return ErrMalformedKey
|
|
}
|
|
var err error
|
|
if verb == "cas" {
|
|
_, err = fmt.Fprintf(rw, "%s %s %d %d %d %d\r\n",
|
|
verb, item.Key, item.Flags, item.Expiration, len(item.Value), item.casid)
|
|
} else {
|
|
_, err = fmt.Fprintf(rw, "%s %s %d %d %d\r\n",
|
|
verb, item.Key, item.Flags, item.Expiration, len(item.Value))
|
|
}
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if _, err = rw.Write(item.Value); err != nil {
|
|
return err
|
|
}
|
|
if _, err := rw.Write(crlf); err != nil {
|
|
return err
|
|
}
|
|
if err := rw.Flush(); err != nil {
|
|
return err
|
|
}
|
|
line, err := rw.ReadSlice('\n')
|
|
if err != nil {
|
|
return err
|
|
}
|
|
switch {
|
|
case bytes.Equal(line, resultStored):
|
|
return nil
|
|
case bytes.Equal(line, resultNotStored):
|
|
return ErrNotStored
|
|
case bytes.Equal(line, resultExists):
|
|
return ErrCASConflict
|
|
case bytes.Equal(line, resultNotFound):
|
|
return ErrCacheMiss
|
|
}
|
|
return fmt.Errorf("memcache: unexpected response line from %q: %q", verb, string(line))
|
|
}
|
|
|
|
func writeReadLine(rw *bufio.ReadWriter, format string, args ...interface{}) ([]byte, error) {
|
|
_, err := fmt.Fprintf(rw, format, args...)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if err := rw.Flush(); err != nil {
|
|
return nil, err
|
|
}
|
|
line, err := rw.ReadSlice('\n')
|
|
return line, err
|
|
}
|
|
|
|
func writeExpectf(rw *bufio.ReadWriter, expect []byte, format string, args ...interface{}) error {
|
|
line, err := writeReadLine(rw, format, args...)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
switch {
|
|
case bytes.Equal(line, resultOK):
|
|
return nil
|
|
case bytes.Equal(line, expect):
|
|
return nil
|
|
case bytes.Equal(line, resultNotStored):
|
|
return ErrNotStored
|
|
case bytes.Equal(line, resultExists):
|
|
return ErrCASConflict
|
|
case bytes.Equal(line, resultNotFound):
|
|
return ErrCacheMiss
|
|
}
|
|
return fmt.Errorf("memcache: unexpected response line: %q", string(line))
|
|
}
|
|
|
|
// Delete deletes the item with the provided key. The error ErrCacheMiss is
|
|
// returned if the item didn't already exist in the cache.
|
|
func (c *Client) Delete(key string) error {
|
|
return c.withKeyRw(key, func(rw *bufio.ReadWriter) error {
|
|
return writeExpectf(rw, resultDeleted, "delete %s\r\n", key)
|
|
})
|
|
}
|
|
|
|
// DeleteAll deletes all items in the cache.
|
|
func (c *Client) DeleteAll() error {
|
|
return c.withKeyRw("", func(rw *bufio.ReadWriter) error {
|
|
return writeExpectf(rw, resultDeleted, "flush_all\r\n")
|
|
})
|
|
}
|
|
|
|
// 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 (c *Client) Increment(key string, delta uint64) (newValue uint64, err error) {
|
|
return c.incrDecr("incr", key, delta)
|
|
}
|
|
|
|
// 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 (c *Client) Decrement(key string, delta uint64) (newValue uint64, err error) {
|
|
return c.incrDecr("decr", key, delta)
|
|
}
|
|
|
|
func (c *Client) incrDecr(verb, key string, delta uint64) (uint64, error) {
|
|
var val uint64
|
|
err := c.withKeyRw(key, func(rw *bufio.ReadWriter) error {
|
|
line, err := writeReadLine(rw, "%s %s %d\r\n", verb, key, delta)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
switch {
|
|
case bytes.Equal(line, resultNotFound):
|
|
return ErrCacheMiss
|
|
case bytes.HasPrefix(line, resultClientErrorPrefix):
|
|
errMsg := line[len(resultClientErrorPrefix) : len(line)-2]
|
|
return errors.New("memcache: client error: " + string(errMsg))
|
|
}
|
|
val, err = strconv.ParseUint(string(line[:len(line)-2]), 10, 64)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
return nil
|
|
})
|
|
return val, err
|
|
}
|