forked from minio/minio
/
queuestore.go
206 lines (172 loc) · 4.38 KB
/
queuestore.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
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
/*
* MinIO Cloud Storage, (C) 2019 MinIO, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package target
import (
"encoding/json"
"io/ioutil"
"math"
"os"
"path/filepath"
"sort"
"sync"
"github.com/minio/minio/pkg/event"
"github.com/minio/minio/pkg/sys"
)
const (
defaultLimit = 100000 // Default store limit.
eventExt = ".event"
)
// QueueStore - Filestore for persisting events.
type QueueStore struct {
sync.RWMutex
currentEntries uint64
entryLimit uint64
directory string
}
// NewQueueStore - Creates an instance for QueueStore.
func NewQueueStore(directory string, limit uint64) Store {
if limit == 0 {
limit = defaultLimit
_, maxRLimit, err := sys.GetMaxOpenFileLimit()
if err == nil {
// Limit the maximum number of entries
// to maximum open file limit
if maxRLimit < limit {
limit = maxRLimit
}
}
}
return &QueueStore{
directory: directory,
entryLimit: limit,
}
}
// Open - Creates the directory if not present.
func (store *QueueStore) Open() error {
store.Lock()
defer store.Unlock()
if err := os.MkdirAll(store.directory, os.FileMode(0770)); err != nil {
return err
}
names, err := store.list()
if err != nil {
return err
}
currentEntries := uint64(len(names))
if currentEntries >= store.entryLimit {
return errLimitExceeded
}
store.currentEntries = currentEntries
return nil
}
// write - writes event to the directory.
func (store *QueueStore) write(key string, e event.Event) error {
// Marshalls the event.
eventData, err := json.Marshal(e)
if err != nil {
return err
}
path := filepath.Join(store.directory, key+eventExt)
if err := ioutil.WriteFile(path, eventData, os.FileMode(0770)); err != nil {
return err
}
// Increment the event count.
store.currentEntries++
return nil
}
// Put - puts a event to the store.
func (store *QueueStore) Put(e event.Event) error {
store.Lock()
defer store.Unlock()
if store.currentEntries >= store.entryLimit {
return errLimitExceeded
}
key, err := getNewUUID()
if err != nil {
return err
}
return store.write(key, e)
}
// Get - gets a event from the store.
func (store *QueueStore) Get(key string) (event event.Event, err error) {
store.RLock()
defer func(store *QueueStore) {
store.RUnlock()
if err != nil {
// Upon error we remove the entry.
store.Del(key)
}
}(store)
var eventData []byte
eventData, err = ioutil.ReadFile(filepath.Join(store.directory, key+eventExt))
if err != nil {
return event, err
}
if len(eventData) == 0 {
return event, os.ErrNotExist
}
if err = json.Unmarshal(eventData, &event); err != nil {
return event, err
}
return event, nil
}
// Del - Deletes an entry from the store.
func (store *QueueStore) Del(key string) error {
store.Lock()
defer store.Unlock()
return store.del(key)
}
// lockless call
func (store *QueueStore) del(key string) error {
if err := os.Remove(filepath.Join(store.directory, key+eventExt)); err != nil {
return err
}
// Decrement the current entries count.
store.currentEntries--
// Current entries can underflow, when multiple
// events are being pushed in parallel, this code
// is needed to ensure that we don't underflow.
//
// queueStore replayEvents is not serialized,
// this code is needed to protect us under
// such situations.
if store.currentEntries == math.MaxUint64 {
store.currentEntries = 0
}
return nil
}
// List - lists all files from the directory.
func (store *QueueStore) List() ([]string, error) {
store.RLock()
defer store.RUnlock()
return store.list()
}
// list lock less.
func (store *QueueStore) list() ([]string, error) {
var names []string
files, err := ioutil.ReadDir(store.directory)
if err != nil {
return names, err
}
// Sort the dentries.
sort.Slice(files, func(i, j int) bool {
return files[i].ModTime().Before(files[j].ModTime())
})
for _, file := range files {
names = append(names, file.Name())
}
return names, nil
}