Support for contexts

.gitignore

@@ -1,3 +1,4 @@
 _*
 *.out
 *~
+.idea

memcache/conn.go

@@ -0,0 +1,37 @@
+package memcache
+
+import (
+	"bufio"
+	"net"
+	"time"
+)
+
+// conn is a connection to a server.
+type conn struct {
+	nc   net.Conn
+	rw   *bufio.ReadWriter
+	addr net.Addr
+	c    *Client
+}
+
+// release returns this connection back to the client's free pool
+func (cn *conn) release() {
+	cn.c.putFreeConn(cn.addr, cn)
+}
+
+func (cn *conn) extendDeadline() {
+	cn.nc.SetDeadline(time.Now().Add(cn.c.netTimeout()))
+}
+
+// condRelease releases this connection if the error pointed to by err
+// is nil (not an error) or is only a protocol level error (e.g. a
+// cache miss).  The purpose is to not recycle TCP connections that
+// are bad.
+func (cn *conn) condRelease(err *error) {
+	if *err == nil || resumableError(*err) {
+		cn.release()
+	} else {
+		cn.nc.Close()
+	}
+}
+

memcache/errors.go

@@ -0,0 +1,46 @@
+package memcache
+
+import (
+	"errors"
+	"net"
+)
+
+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")
+
+	// ErrServerError 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")
+)
+
+// 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.
+type ConnectTimeoutError struct {
+	Addr net.Addr
+}
+
+func (cte *ConnectTimeoutError) Error() string {
+	return "memcache: connect timeout to " + cte.Addr.String()
+}

memcache/helpers.go

@@ -0,0 +1,79 @@
+package memcache
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+)
+
+// resumableError returns true if err is only a protocol-level cache error.
+// This is used to determine whether or not a server connection should
+// be re-used or not. If an error occurs, by default we don't reuse the
+// connection, unless it was just a cache error.
+func resumableError(err error) bool {
+	switch err {
+	case ErrCacheMiss, ErrCASConflict, ErrNotStored, ErrMalformedKey:
+		return true
+	}
+	return false
+}
+
+func legalKey(key string) bool {
+	if len(key) > 250 {
+		return false
+	}
+	for i := 0; i < len(key); i++ {
+		if key[i] <= ' ' || key[i] == 0x7f {
+			return false
+		}
+	}
+	return true
+}
+
+// scanGetResponseLine populates it and returns the declared size of the item.
+// It does not read the bytes of the item.
+func scanGetResponseLine(line []byte, it *Item) (size int, err error) {
+	pattern := "VALUE %s %d %d %d\r\n"
+	dest := []interface{}{&it.Key, &it.Flags, &size, &it.casid}
+	if bytes.Count(line, space) == 3 {
+		pattern = "VALUE %s %d %d\r\n"
+		dest = dest[:3]
+	}
+	n, err := fmt.Sscanf(string(line), pattern, dest...)
+	if err != nil || n != len(dest) {
+		return -1, fmt.Errorf("memcache: unexpected line in get response: %q", line)
+	}
+	return size, nil
+}
+
+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))
+}

memcache/item.go

@@ -0,0 +1,22 @@
+package memcache
+
+// Item is an item to be got or stored in a memcached server.
+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
+
+	// Compare and swap ID.
+	casid uint64
+}