-
Notifications
You must be signed in to change notification settings - Fork 39
/
selector.go
62 lines (55 loc) · 1.05 KB
/
selector.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
package selector
import (
"errors"
"hash/crc32"
"sync"
)
// All is a Selector that returns all servers
type All struct {
sync.RWMutex
servers []string
}
// Shard is a Selector that shards to a single server
type Shard struct {
sync.RWMutex
servers []string
}
func (sa *All) Get(topic string) ([]string, error) {
sa.RLock()
if len(sa.servers) == 0 {
sa.RUnlock()
return nil, errors.New("no servers")
}
servers := sa.servers
sa.RUnlock()
return servers, nil
}
func (sa *All) Set(servers ...string) error {
sa.Lock()
sa.servers = servers
sa.Unlock()
return nil
}
func (ss *Shard) Get(topic string) ([]string, error) {
ss.RLock()
length := len(ss.servers)
if length == 0 {
ss.RUnlock()
return nil, errors.New("no servers")
}
if length == 1 {
servers := ss.servers
ss.RUnlock()
return servers, nil
}
cs := crc32.ChecksumIEEE([]byte(topic))
server := ss.servers[cs%uint32(length)]
ss.RUnlock()
return []string{server}, nil
}
func (ss *Shard) Set(servers ...string) error {
ss.Lock()
ss.servers = servers
ss.Unlock()
return nil
}