func incr(c appengine.Context, key string, delta int64, initialValue *uint64) (newValue uint64, err error) {
req := &pb.MemcacheIncrementRequest{
Key: []byte(key),
InitialValue: initialValue,
}
if delta >= 0 {
req.Delta = proto.Uint64(uint64(delta))
} else {
req.Delta = proto.Uint64(uint64(-delta))
req.Direction = pb.MemcacheIncrementRequest_DECREMENT.Enum()
}
res := &pb.MemcacheIncrementResponse{}
err = c.Call("memcache", "Increment", req, res, nil)
if err != nil {
return
}
if res.NewValue == nil {
return 0, ErrCacheMiss
}
return *res.NewValue, nil
}
// set sets the given items using the given conflict resolution policy.
// appengine.MultiError may be returned.
func set(c appengine.Context, item []*Item, value [][]byte, policy pb.MemcacheSetRequest_SetPolicy) error {
req := &pb.MemcacheSetRequest{
Item: make([]*pb.MemcacheSetRequest_Item, len(item)),
}
for i, t := range item {
p := &pb.MemcacheSetRequest_Item{
Key: []byte(t.Key),
}
if value == nil {
p.Value = t.Value
} else {
p.Value = value[i]
}
if t.Flags != 0 {
p.Flags = proto.Uint32(t.Flags)
}
if t.Expiration != 0 {
// In the .proto file, MemcacheSetRequest_Item uses a fixed32 (i.e. unsigned)
// for expiration time, while MemcacheGetRequest_Item uses int32 (i.e. signed).
// Throughout this .go file, we use int32.
// Also, in the proto, the expiration value is either a duration (in seconds)
// or an absolute Unix timestamp (in seconds), depending on whether the
// value is less than or greater than or equal to 30 years, respectively.
if t.Expiration < time.Second {
// Because an Expiration of 0 means no expiration, we take
// care here to translate an item with an expiration
// Duration between 0-1 seconds as immediately expiring
// (saying it expired a few seconds ago), rather than
// rounding it down to 0 and making it live forever.
p.ExpirationTime = proto.Uint32(uint32(time.Now().Unix()) - 5)
} else if t.Expiration >= thirtyYears {
p.ExpirationTime = proto.Uint32(uint32(time.Now().Unix()) + uint32(t.Expiration/time.Second))
} else {
p.ExpirationTime = proto.Uint32(uint32(t.Expiration / time.Second))
}
}
if t.casID != 0 {
p.CasId = proto.Uint64(t.casID)
p.ForCas = proto.Bool(true)
}
p.SetPolicy = policy.Enum()
req.Item[i] = p
}
res := &pb.MemcacheSetResponse{}
if err := c.Call("memcache", "Set", req, res, nil); err != nil {
return err
}
if len(res.SetStatus) != len(item) {
return ErrServerError
}
me, any := make(appengine.MultiError, len(item)), false
for i, st := range res.SetStatus {
var err error
switch st {
case pb.MemcacheSetResponse_STORED:
// OK
case pb.MemcacheSetResponse_NOT_STORED:
err = ErrNotStored
case pb.MemcacheSetResponse_EXISTS:
err = ErrCASConflict
default:
err = ErrServerError
}
if err != nil {
me[i] = err
any = true
}
}
if any {
return me
}
return nil
}