-
Notifications
You must be signed in to change notification settings - Fork 0
/
cache.go
761 lines (617 loc) · 19.1 KB
/
cache.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
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
package radir
/*
cache.go offers a generic, thread-safe, in-memory Registration/Registrant
caching subsystem.
*/
import (
"encoding/gob"
"os"
"sync"
"time"
)
/*
cachedRegistration contains a *[Registration] instance alongside an
expiry [time.Time] instance.
Instances of this type are stored within an instance of *[Cache] and
need not be managed directly by the user.
*/
type cachedRegistration struct {
Value *Registration
Expiry time.Time
}
/*
cachedRegistrant contains a *[Registrant] instance alongside
an expiry [time.Time] instance.
Instances of this type are stored within an instance of *[Cache] and
need not be managed directly by the user.
*/
type cachedRegistrant struct {
Value *Registrant
Expiry time.Time
}
/*
Expired returns a Boolean value indicative of whether the receiver
instance has expired. A value of true is returned if the instance
cannot be found.
Note that, unlike [Cache.Registration], use of this method will not
result in the deletion of an expired instance.
*/
func (r *Cache) RegistrationExpired(dn string) bool {
return r.expired(dn, 0)
}
/*
Expired returns a Boolean value indicative of whether the receiver
instance has expired. A value of true is returned if the instance
cannot be found.
Note that, unlike [Cache.Registrant], use of this method will not
result in the deletion of an expired instance.
*/
func (r *Cache) RegistrantExpired(dn string) bool {
return r.expired(dn, 1)
}
func (r *Cache) expired(dn string, t int) bool {
if r.IsZero() {
return false
}
if len(dn) == 0 {
return false
}
r.lock.Lock()
defer r.lock.Unlock()
key := lc(dn)
if t == 0 {
if item, _ := r.registrations[key]; item.Value != nil {
return now().After(item.Expiry)
}
return true
}
if item, _ := r.registrants[key]; item.Value != nil {
return now().After(item.Expiry)
}
return true
}
/*
Cache is a thread-safe, memory-based caching type, meant to store any
number of *[Registrant] and *[Registration] instances for the
purpose of reducing LDAP utilization. Caching is covered in the [RADUA]
and [RASCHEMA] IDs.
Instances of either type are associated with their respective LDAP DNs,
which are queried immediately prior to an LDAP Search.
Unexpired instances found within a *[Cache] that match the queried DN are
returned instead of reaching out to the RA DSA.
Requesting cached instances that have since expired will result in their
immediate annihilation and a nil return. Under ordinary circumstances,
at this point the DUA could reach out to the directory in an attempt to
re-acquire the now-expired instance.
The [NewCache] function initializes and returns instances of this type.
Following initialization, an instance of *[Cache] may be written to file
using the [Cache.WriteRegistrations] and [Cache.WriteRegistrants] methods.
Conversely, the [Cache.LoadRegistrations] and [Cache.LoadRegistrants]
methods allow an unfrozen *[Cache] to be loaded from file.
The [Cache.Registration] and [Cache.Registrant] methods allow accessing
unexpired cached instances. Attempting to access a cached instance that
has since expired will result in its deletion unless the *[Cache] has
been frozen.
The [Cache.RegistrationLen] and [Cache.RegistrantLen] methods return the
current respective integer length of a *[Cache]. The [Cache.RegistrationCap]
and [Cache.RegistrantCap] return the maximum number of elements within a
*[Cache].
The [Cache.RegistrationExpired] and [Cache.RegistrantExpired] methods
safely allow expiration checks of specific cached instances without the
risk of deletion. The [Cache.RegistrationKeys] and [Cache.RegistrantKeys]
return string slices of cached element DNs, also without deletion risk.
The [Cache.Add] method allows the addition of elements into the *[Cache],
provided it is not frozen.
The [Cache.RemoveRegistration] and [Cache.RemoveRegistrant] methods allow
for the removal of select instances from an unfrozen *[Cache], regardless
of the expiration status.
The [Cache.TouchRegistration] and [Cache.TouchRegistrant] methods allow
for expired -- but as-of-yet undeleted -- cached instances to be "reborn"
or "resurrected" if the *[Cache] is not frozen. A "touch" effectively
results in the reset of the respective "expiration timer" to the specified
duration.
The [Cache.Freeze] and [Cache.Thaw] methods impose read-only and read-write
policies respectively, influencing the ability for updates and amendments
to the *[Cache] to be recognized. The [Cache.Frozen] method offers a means
for checking the frozen state of a *[Cache]. A frozen *[Cache] will always
permit read operations. When first initialized, a *[Cache] is always in a
thawed state.
[Cache.Tidy] and [Cache.Flush] can be used to clean-up or outright purge
multiple instances from an unfrozen *[Cache]. The [Cache.IsZero] method
reveals whether the instance has been initialized or not. [Cache.Free]
destroys the *[Cache] -- regardless of freeze state.
[RADUA]: https://datatracker.ietf.org/doc/html/draft-coretta-oiddir-radua
[RASCHEMA]: https://datatracker.ietf.org/doc/html/draft-coretta-oiddir-schema
*/
type Cache struct {
threshold [2]int
lock *sync.Mutex
frozen bool
registrations map[string]cachedRegistration
registrants map[string]cachedRegistrant
}
/*
NewCache returns a freshly initialized instance of *[Cache].
The registrationMax and registrantMax integer input values define the
maximum number of entries that will be cached respectively. Specifying
0 disables the respective threshold.
Attempts to exceed this threshold will silently disregard submissions
for NEW (uncached) instances, however previously cached instances will
still be refreshed.
*/
func NewCache(registrationMax, registrantMax int) *Cache {
return newCache(registrationMax, registrantMax)
}
func newCache(registrationMax, registrantMax int) *Cache {
var max [2]int
if registrationMax < 0 {
registrationMax = 0
}
if registrantMax < 0 {
registrantMax = 0
}
max = [2]int{registrationMax, registrantMax}
return &Cache{
threshold: max,
lock: &sync.Mutex{},
registrations: make(map[string]cachedRegistration, max[0]),
registrants: make(map[string]cachedRegistrant, max[1]),
}
}
/*
IsZero returns a Boolean value indicative of a nil receiver state.
*/
func (r *Cache) IsZero() bool {
return r == nil
}
/*
RegistrationLen returns the integer length of the receiver instance, thereby
revealing how many *[Registration] instances are cached. This does not take
expiration status into account.
*/
func (r *Cache) RegistrationLen() int {
return len(r.registrations)
}
/*
RegistrationCap returns the maximum permitted number of *[Registration]
instances that may be cached. A value of zero (0) indicates no limits are
imposed upon caching requests of this form.
*/
func (r *Cache) RegistrationCap() int {
return r.threshold[0]
}
/*
RegistrantLen returns the integer length of the receiver instance, thereby
revealing how many *[Registrant] instances are cached. This does
not take expiration status into account.
*/
func (r *Cache) RegistrantLen() int {
return len(r.registrants)
}
/*
RegistrantCap returns the maximum permitted number of *[Registrant]
instances that may be cached. A value of zero (0) indicates no limits are
imposed upon caching requests of this form.
*/
func (r *Cache) RegistrantCap() int {
return r.threshold[1]
}
/*
Registration returns an instance of *[Registration] following a search for
the input dn value within the receiver instance.
A nil return value can indicate any of the following:
- Instance had expired and has since been purged, or has not yet been cached
- Instance was found but was nil, indicating caching is disabled for the entry
Case is not significant in the matching process.
*/
func (r *Cache) Registration(dn string) *Registration {
reg, _ := r.get(dn, 0).(*Registration)
return reg
}
/*
Registrant returns a *[Registrant] instance following a search
for the input dn value within the receiver instance.
A nil return value can indicate any of the following:
- Instance had expired and has since been purged, or has not yet been cached
- Instance was found but was nil, indicating caching is disabled for the entry
Case is not significant in the matching process.
*/
func (r *Cache) Registrant(dn string) *Registrant {
reg, _ := r.get(dn, 1).(*Registrant)
return reg
}
func (r *Cache) get(dn string, t int) any {
if r.IsZero() {
return nil
}
r.lock.Lock()
defer r.lock.Unlock()
key := lc(dn)
if t == 0 {
item, ok := r.registrations[key]
if ok && item.Value != nil {
if now().After(item.Expiry) {
r.deleteRegistration(key)
return nil
}
}
return item.Value
}
item, ok := r.registrants[key]
if ok && item.Value != nil {
if now().After(item.Expiry) {
r.deleteRegistrant(key)
return nil
}
}
return item.Value
}
/*
RegistrationKeys returns slices of cached element DNs, each representing
a *[Registration] instance present within the receiver.
Expiration status is not taken into account, nor are any expired elements
purged from the receiver as a result of using this method.
*/
func (r *Cache) RegistrationKeys() []string {
return r.keys(0)
}
/*
RegistrantKeys returns slices of cached element DNs, each representing
a *[Registrant] instance present within the receiver.
Expiration status is not taken into account, nor are any expired elements
purged from the receiver as a result of using this method.
*/
func (r *Cache) RegistrantKeys() []string {
return r.keys(1)
}
func (r *Cache) keys(t int) (keys []string) {
if !r.IsZero() {
appender := func(dn string) {
if len(dn) > 0 {
keys = append(keys, dn)
}
}
r.lock.Lock()
defer r.lock.Unlock()
if t == 0 {
for _, v := range r.registrations {
appender(v.Value.DN())
}
return
}
for _, v := range r.registrants {
appender(v.Value.DN())
}
}
return
}
/*
TouchRegistration will refresh the targeted *[Registration] instance by
the input dn value, and replace its Expiry struct field with a fresh
[time.Time] instance based upon the input minutes value, which may be a
string or an int.
In addition to preserving instances past their original expiration time,
this method may be used to "resurrect" instances that have since expired
but have not yet been purged from the receiver instance.
This method has no effect if the targeted instance is not found, the receiver
is zero, or the minutes value is <= 0.
*/
func (r *Cache) TouchRegistration(dn string, minutes any) {
r.touch(dn, minutes, 0)
}
/*
TouchRegistrant will refresh the targeted *[Registrant] instance
by the input dn value, and replace its Expiry struct field with a fresh
[time.Time] instance based upon the input minutes value, which may be a
string or an int.
In addition to preserving instances past their original expiration time,
this method may be used to "resurrect" instances that have since expired
but have not yet been purged from the receiver instance.
This method has no effect if the targeted instance is not found, the receiver
is zero, or the minutes value is <= 0.
*/
func (r *Cache) TouchRegistrant(dn string, minutes any) {
r.touch(dn, minutes, 1)
}
func (r *Cache) touch(dn string, minutes any, t int) {
if r.IsZero() || r.Frozen() {
return
}
min := assertTTL(minutes)
if len(dn) == 0 || min <= 0 {
return
}
r.lock.Lock()
defer r.lock.Unlock()
key := lc(dn)
if t == 0 {
if item, _ := r.registrations[key]; item.Value != nil {
item.Expiry = newExpiry(min)
}
return
}
if item, _ := r.registrants[key]; item.Value != nil {
item.Expiry = newExpiry(min)
}
}
/*
Add assigns the input *[Registration] or *[Registrant] instance
to the receiver instance. The minutes input value (which may be a string
or an int) should correspond to one of the following states:
- <=0 (entry default) indicates no caching for the indicated instance (always call LDAP)
- All other positive values indicate a cached lifespan in minutes (cache and don't call LDAP for this entry until N minutes)
If the target instance is already cached, it shall be replaced with the
input instance, and will be subject to the new lifespan value. This will
achieve the same outcome as use of [Cache.Touch].
This method is meant for use either of the following scenarios:
- Automatically, whereby an 'rATTL' or 'c-rATTL' value has been set within the RA DIT and is being observed following retrieval one or more LDAP entries to be marshaled
- Manually, whereby an instance crafted by the user is being deliberately cached, whether or not LDAP is presently involved
Input instances may be cached at any point, whether modified or not.
*/
func (r *Cache) Add(instance, minutes any) {
if r.IsZero() || r.Frozen() {
return
}
min := assertTTL(minutes)
if instance == nil {
return
}
switch tv := instance.(type) {
case *Registration:
if len(tv.DN()) > 0 {
r.cacheRegistration(tv, min)
}
case *Registrant:
if len(tv.DN()) > 0 {
r.cacheRegistrant(tv, min)
}
}
}
/*
RemoveRegistration deletes the specified *[Registration] instances from
the receiver instance.
Case is not significant in the matching process.
*/
func (r *Cache) RemoveRegistration(dn ...string) {
r.remove(1, dn...)
}
/*
RemoveRegistrant deletes the specified *[Registrant] instances
from the receiver instance.
Case is not significant in the matching process.
*/
func (r *Cache) RemoveRegistrant(dn ...string) {
r.remove(1, dn...)
}
func (r *Cache) remove(t int, keys ...string) {
if r.IsZero() {
return
} else if len(keys) == 0 {
return
} else if r.Frozen() {
return
}
r.lock.Lock()
defer r.lock.Unlock()
if t == 0 {
r.deleteRegistration(keys...)
} else {
r.deleteRegistrant(keys...)
}
}
func (r *Cache) registrationsFull() bool {
return r.threshold[0] <= len(r.registrations) && r.threshold[0] != 0
}
func (r *Cache) cacheRegistration(reg *Registration, minutes any) {
if r.Registration(reg.DN()) == nil {
// reg is not presently cached.
if r.registrationsFull() {
// cannot cache: full house
return
}
}
ttl := assertTTL(minutes)
if ttl <= 0 {
return
}
r.lock.Lock()
defer r.lock.Unlock()
key := lc(reg.DN())
r.registrations[key] = cachedRegistration{
Value: reg,
Expiry: newExpiry(ttl),
}
}
func (r *Cache) registrantsFull() bool {
return r.threshold[1] <= len(r.registrants) && r.threshold[1] != 0
}
func (r *Cache) cacheRegistrant(reg *Registrant, minutes any) {
if r.Registrant(reg.DN()) == nil {
// reg is not presently cached.
if r.registrantsFull() {
// cannot cache: full house
return
}
}
ttl := assertTTL(minutes)
if ttl <= 0 {
return
}
r.lock.Lock()
defer r.lock.Unlock()
key := lc(reg.DN())
r.registrants[key] = cachedRegistrant{
Value: reg,
Expiry: newExpiry(ttl),
}
}
/*
Freeze freezes the receiver instance, thereby preventing any subsequent
updates and clean-ups from proceeding. This means no expirations (removals)
of expired cache entries will occur, nor can any new elements be added to
the instance. Cached elements may still be accessed using conventional means.
See the [Cache.Thaw] method for a means of unfreezing the receiver instance.
See the [Cache.Frozen] method for a means of confirming a frozen or thawed
state.
Note that the receiver can still be freed (destroyed) by [Cache.Free]
while frozen.
*/
func (r *Cache) Freeze() {
if !r.IsZero() && !r.Frozen() {
r.lock.Lock()
defer r.lock.Unlock()
r.frozen = true
}
}
/*
Thaw unfreezes the receiver instance, thereby allowing any subsequent
updates and clean-ups to proceed. This means that expirations (removals)
of expired cache entries will occur, and new elements may be added to
the instance.
See the [Cache.Freeze] method for a means of freezing the receiver instance.
See the [Cache.Frozen] method for a means of confirming a frozen state.
*/
func (r *Cache) Thaw() {
if !r.IsZero() && r.Frozen() {
r.lock.Lock()
defer r.lock.Unlock()
r.frozen = false
}
}
/*
Frozen returns a Boolean value indicative of a frozen receiver state.
During a freeze state, no new elements may be added to the instance,
nor can expired elements be purged.
Note that the receiver can still be freed (destroyed) by [Cache.Free]
while frozen.
*/
func (r *Cache) Frozen() bool {
return r.frozen
}
/*
Free frees (destroys) the *[Cache] instance, rendering it nil and unusable.
Note that this method is immutable, and will not honor any frozen state or
mutex lock.
*/
func (r *Cache) Free() {
*r = Cache{}
}
/*
Flush will purge all cached *[Registration] or *[Registrant] instances
from the receiver, regardless of expiration status. Following completion,
the receiver remains initialized and usable.
*/
func (r *Cache) Flush() {
r.flush(true)
}
/*
Tidy scans for, and purges the receiver instance of, any *[Registration]
or *[Registrant] instance which have expired.
*/
func (r *Cache) Tidy() {
r.flush(false)
}
func (r *Cache) flush(all bool) {
if r.IsZero() || r.Frozen() {
return
}
r.lock.Lock()
defer r.lock.Unlock()
for k, v := range r.registrations {
if now().After(v.Expiry) || all {
r.deleteRegistration(k)
}
}
for k, v := range r.registrants {
if now().After(v.Expiry) || all {
r.deleteRegistrant(k)
}
}
}
/*
newExpiry returns an instance of [time.Time] that defines when a given
item will be considered expired and needing refresh.
*/
func newExpiry(min int) time.Time {
return now().Add(time.Duration(min) * time.Minute)
}
/*
WriteRegistrations returns an error following an attempt to write the
current contents of the *[Registration] cache to the filename indicated.
*/
func (r *Cache) WriteRegistrations(filename string) error {
return r.write(filename, 0)
}
/*
WriteRegistrants returns an error following an attempt to write the current
contents of the *[Registrant] cache to the filename indicated.
*/
func (r *Cache) WriteRegistrants(filename string) error {
return r.write(filename, 1)
}
func (r *Cache) write(filename string, t int) error {
if r.IsZero() {
return nil // nothing to write!
}
file, err := os.Create(filename)
if err != nil {
return err
}
defer file.Close()
codec := gob.NewEncoder(file)
if t == 0 {
err = codec.Encode(r.registrations)
} else {
err = codec.Encode(r.registrants)
}
return err
}
/*
LoadRegistrations returns an error following an attempt to read the filename
indicated into the receiver's *[Registration] cache.
*/
func (r *Cache) LoadRegistrations(filename string) error {
return r.load(filename, 0)
}
/*
LoadRegistrations returns an error following an attempt to read the filename
indicated into the receiver's *[Registrant] cache.
If the receiver instance is zero (uninitialized), a [NilCacheErr] is returned.
If the receiver is frozen, a [FrozenCacheErr] is returned.
*/
func (r *Cache) LoadRegistrants(filename string) error {
return r.load(filename, 1)
}
func (r *Cache) load(filename string, t int) error {
if r.IsZero() {
return NilCacheErr
} else if r.Frozen() {
return FrozenCacheErr
}
file, err := os.Open(filename)
if err != nil {
return err
}
defer file.Close()
codec := gob.NewDecoder(file)
if t == 0 {
err = codec.Decode(&r.registrations)
} else {
err = codec.Decode(&r.registrants)
}
return err
}
func (r *Cache) deleteRegistration(dn ...string) {
if !r.Frozen() {
for _, x := range dn {
delete(r.registrations, lc(x))
}
}
}
func (r *Cache) deleteRegistrant(dn ...string) {
if !r.Frozen() {
for _, x := range dn {
delete(r.registrants, lc(x))
}
}
}