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
|
// 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 transactions
import (
"sync"
"time"
"github.com/matrix-org/util"
)
// DefaultCleanupPeriod represents the default time duration after which cacheCleanService runs.
const DefaultCleanupPeriod time.Duration = 30 * time.Minute
type txnsMap map[CacheKey]*util.JSONResponse
// CacheKey is the type for the key in a transactions cache.
// This is needed because the spec requires transaction IDs to have a per-access token scope.
type CacheKey struct {
AccessToken string
TxnID string
}
// Cache represents a temporary store for response entries.
// Entries are evicted after a certain period, defined by cleanupPeriod.
// This works by keeping two maps of entries, and cycling the maps after the cleanupPeriod.
type Cache struct {
sync.RWMutex
txnsMaps [2]txnsMap
cleanupPeriod time.Duration
}
// New is a wrapper which calls NewWithCleanupPeriod with DefaultCleanupPeriod as argument.
func New() *Cache {
return NewWithCleanupPeriod(DefaultCleanupPeriod)
}
// NewWithCleanupPeriod creates a new Cache object, starts cacheCleanService.
// Takes cleanupPeriod as argument.
// Returns a reference to newly created Cache.
func NewWithCleanupPeriod(cleanupPeriod time.Duration) *Cache {
t := Cache{txnsMaps: [2]txnsMap{make(txnsMap), make(txnsMap)}}
t.cleanupPeriod = cleanupPeriod
// Start clean service as the Cache is created
go cacheCleanService(&t)
return &t
}
// FetchTransaction looks up an entry for the (accessToken, txnID) tuple in Cache.
// Looks in both the txnMaps.
// Returns (JSON response, true) if txnID is found, else the returned bool is false.
func (t *Cache) FetchTransaction(accessToken, txnID string) (*util.JSONResponse, bool) {
t.RLock()
defer t.RUnlock()
for _, txns := range t.txnsMaps {
res, ok := txns[CacheKey{accessToken, txnID}]
if ok {
return res, true
}
}
return nil, false
}
// AddTransaction adds an entry for the (accessToken, txnID) tuple in Cache.
// Adds to the front txnMap.
func (t *Cache) AddTransaction(accessToken, txnID string, res *util.JSONResponse) {
t.Lock()
defer t.Unlock()
t.txnsMaps[0][CacheKey{accessToken, txnID}] = res
}
// cacheCleanService is responsible for cleaning up entries after cleanupPeriod.
// It guarantees that an entry will be present in cache for at least cleanupPeriod & at most 2 * cleanupPeriod.
// This cycles the txnMaps forward, i.e. back map is assigned the front and front is assigned an empty map.
func cacheCleanService(t *Cache) {
ticker := time.NewTicker(t.cleanupPeriod).C
for range ticker {
t.Lock()
t.txnsMaps[1] = t.txnsMaps[0]
t.txnsMaps[0] = make(txnsMap)
t.Unlock()
}
}
|
