forked from boltdb/bolt
-
Notifications
You must be signed in to change notification settings - Fork 1
/
batch_example_test.go
148 lines (130 loc) · 3 KB
/
batch_example_test.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
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
package bolt_test
import (
"encoding/binary"
"fmt"
"io/ioutil"
"log"
"math/rand"
"net/http"
"net/http/httptest"
"os"
"github.com/boltdb/bolt"
)
// Set this to see how the counts are actually updated.
const verbose = false
// Counter updates a counter in Bolt for every URL path requested.
type counter struct {
db *bolt.DB
}
func (c counter) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
// Communicates the new count from a successful database
// transaction.
var result uint64
increment := func(tx *bolt.Tx) error {
b, err := tx.CreateBucketIfNotExists([]byte("hits"))
if err != nil {
return err
}
key := []byte(req.URL.String())
// Decode handles key not found for us.
count := decode(b.Get(key)) + 1
b.Put(key, encode(count))
// All good, communicate new count.
result = count
return nil
}
if err := c.db.Batch(increment); err != nil {
http.Error(rw, err.Error(), 500)
return
}
if verbose {
log.Printf("server: %s: %d", req.URL.String(), result)
}
rw.Header().Set("Content-Type", "application/octet-stream")
fmt.Fprintf(rw, "%d\n", result)
}
func client(id int, base string, paths []string) error {
// Process paths in random order.
rng := rand.New(rand.NewSource(int64(id)))
permutation := rng.Perm(len(paths))
for i := range paths {
path := paths[permutation[i]]
resp, err := http.Get(base + path)
if err != nil {
return err
}
defer resp.Body.Close()
buf, err := ioutil.ReadAll(resp.Body)
if err != nil {
return err
}
if verbose {
log.Printf("client: %s: %s", path, buf)
}
}
return nil
}
func ExampleDB_Batch() {
// Open the database.
db, _ := bolt.Open(tempfile(), 0666, nil)
defer os.Remove(db.Path())
defer db.Close()
// Start our web server
count := counter{db}
srv := httptest.NewServer(count)
defer srv.Close()
// Decrease the batch size to make things more interesting.
db.MaxBatchSize = 3
// Get every path multiple times concurrently.
const clients = 10
paths := []string{
"/foo",
"/bar",
"/baz",
"/quux",
"/thud",
"/xyzzy",
}
errors := make(chan error, clients)
for i := 0; i < clients; i++ {
go func(id int) {
errors <- client(id, srv.URL, paths)
}(i)
}
// Check all responses to make sure there's no error.
for i := 0; i < clients; i++ {
if err := <-errors; err != nil {
fmt.Printf("client error: %v", err)
return
}
}
// Check the final result
db.View(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("hits"))
c := b.Cursor()
for k, v := c.First(); k != nil; k, v = c.Next() {
fmt.Printf("hits to %s: %d\n", k, decode(v))
}
return nil
})
// Output:
// hits to /bar: 10
// hits to /baz: 10
// hits to /foo: 10
// hits to /quux: 10
// hits to /thud: 10
// hits to /xyzzy: 10
}
// encode marshals a counter.
func encode(n uint64) []byte {
buf := make([]byte, 8)
binary.BigEndian.PutUint64(buf, n)
return buf
}
// decode unmarshals a counter. Nil buffers are decoded as 0.
func decode(buf []byte) uint64 {
if buf == nil {
return 0
}
return binary.BigEndian.Uint64(buf)
}