futur.blue
objective categorical abstract machine language personal data server
Implement MST covering proof
+197
-97
+197
-97
mist/lib/mst.ml
+197
-97
mist/lib/mst.ml
···
1
module StringMap = Dag_cbor.StringMap
2
3
type node_raw =
···
37
38
and entry =
39
{layer: int; key: string; value: Cid.t; right: node option Lwt.t Lazy.t}
40
41
let ( let*? ) lazy_opt_lwt f =
42
let%lwt result = Lazy.force lazy_opt_lwt in
···
85
node.entries <- node.entries @ [entry] ;
86
Lwt.return node )
87
88
-
(* helper to find the entry with a given key in a hydrated node *)
89
-
let find_entry_nonrec node key =
90
-
let rec aux entries =
91
match entries with
92
| [] ->
93
-
None
94
-
| e :: es ->
95
-
if e.key = key then Some e else if e.key > key then None else aux es
96
in
97
-
aux node.entries
98
99
-
(* from a list of raw entries, produces a list of their keys *)
100
-
let entries_to_keys entries =
101
-
entries
102
-
|> List.fold_left
103
-
(fun keys entry ->
104
-
let prefix =
105
-
match keys with [] -> "" | prev :: _ -> String.sub prev 0 entry.p
106
-
in
107
-
let path = String.concat "" [prefix; Bytes.to_string entry.k] in
108
-
Util.ensure_valid_key path ; path :: keys )
109
-
[]
110
-
|> List.rev
111
112
-
module Make (Store : Storage.Writable_blockstore) = struct
113
type bs = Store.t
114
115
type t = {blockstore: bs; root: Cid.t}
···
168
| _ ->
169
raise (Invalid_argument "invalid block")
170
171
let retrieve_node_raw t cid : node_raw option Lwt.t =
172
match%lwt Store.get_bytes t.blockstore cid with
173
| Some bytes ->
···
175
| None ->
176
Lwt.return_none
177
178
-
(* retrieves & decodes a node by cid *)
179
let rec retrieve_node t cid : node option Lwt.t =
180
match%lwt retrieve_node_raw t cid with
181
| Some raw ->
···
183
| None ->
184
Lwt.return_none
185
186
and retrieve_node_lazy t cid = lazy (retrieve_node t cid)
187
188
(* hydrates a raw node *)
···
261
traverse t (fun path cid -> ignore (StringMap.add path cid map))
262
in
263
Lwt.return map
264
-
265
-
(* produces a cid and cbor-encoded bytes for this mst *)
266
-
let serialize t map : (Cid.t * bytes) Lwt.t =
267
-
let keys =
268
-
map |> StringMap.bindings |> List.map fst |> List.sort String.compare
269
-
in
270
-
let entry_for_key key =
271
-
let value = StringMap.find key map in
272
-
let height = Util.leading_zeros_on_hash key in
273
-
{layer= height; key; value; right= lazy Lwt.return_none}
274
-
in
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-
let root =
276
-
{ layer= keys |> List.hd |> Util.leading_zeros_on_hash
277
-
; entries= []
278
-
; left= lazy Lwt.return_none }
279
-
in
280
-
List.iter
281
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(fun key -> ignore (insert_entry root (entry_for_key key)))
282
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(List.tl keys) ;
283
-
let rec finalize node : (Cid.t * bytes) Lwt.t =
284
-
let%lwt left =
285
-
node.left
286
-
>>? function
287
-
| Some l ->
288
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let%lwt cid, _ = finalize l in
289
-
Lwt.return_some cid
290
-
| None ->
291
-
Lwt.return_none
292
-
in
293
-
let last_key = ref "" in
294
-
let%lwt mst_entries =
295
-
Lwt_list.map_s
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-
(fun entry ->
297
-
let%lwt right =
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-
entry.right
299
-
>>? function
300
-
| Some r ->
301
-
let%lwt cid, _ = finalize r in
302
-
Lwt.return (Some cid)
303
-
| None ->
304
-
Lwt.return None
305
-
in
306
-
let prefix_len = Util.shared_prefix_length !last_key entry.key in
307
-
last_key := entry.key ;
308
-
Lwt.return
309
-
{ k=
310
-
Bytes.of_string
311
-
(String.sub entry.key prefix_len
312
-
(String.length entry.key - prefix_len) )
313
-
; p= prefix_len
314
-
; v= entry.value
315
-
; t= right } )
316
-
node.entries
317
-
in
318
-
let encoded =
319
-
Dag_cbor.encode (encode_node_raw {l= left; e= mst_entries})
320
-
in
321
-
let cid = Cid.create Dcbor encoded in
322
-
let%lwt () = Store.put_block t.blockstore cid encoded in
323
-
Lwt.return (cid, encoded)
324
-
in
325
-
finalize root
326
327
(* returns cids and blocks that form the path from a given node to a given entry *)
328
let rec path_to_entry t node key : (Cid.t * bytes) list Lwt.t =
329
let%lwt root_bytes = Store.get_bytes t.blockstore node in
330
-
let%lwt root =
331
match root_bytes with
332
| None ->
333
Lwt.return_none
334
| Some bytes ->
335
Lwt.return_some (decode_block_raw bytes)
336
in
337
-
let path_tail = [(node, Option.get root_bytes)] in
338
(* if there is a left child, try to find a path through the left subtree *)
339
let%lwt path_through_left =
340
-
match root with
341
| None ->
342
Lwt.return_some []
343
-
| Some root -> (
344
-
match root.l with
345
| None ->
346
Lwt.return_none
347
| Some left -> (
···
350
Lwt.return_none
351
| path ->
352
(* Option.get is safe because root is Some only when root_bytes is Some *)
353
-
Lwt.return_some (path @ path_tail) ) )
354
in
355
match path_through_left with
356
| Some path ->
357
Lwt.return path
358
| None -> (
359
(* if a left subtree path couldn't be found, find the entry whose right subtree this key would belong to *)
360
-
let entries = (Option.get root).e in
361
-
let entries_keys = entries_to_keys entries in
362
let entries_len = List.length entries in
363
let entry_index =
364
-
match List.find_index (fun e -> e >= key) entries_keys with
365
| Some index ->
366
index
367
| None ->
368
entries_len
369
in
370
(* entry_index here is actually the entry to the right of the subtree the key would belong to *)
371
match entry_index with
372
| _
373
(* because entries[entry_index] might turn out to be the entry we're looking for *)
374
when entry_index < entries_len
375
-
&& List.nth entries_keys entry_index = key ->
376
Lwt.return path_tail
377
| _ -> (
378
(* otherwise, we continue down the right subtree of the entry before entry_index *)
379
-
match Util.last entries with
380
-
| Some last when last.t != None ->
381
let%lwt path_through_right =
382
path_to_entry t (Option.get last.t) key
383
in
384
Lwt.return (path_through_right @ path_tail)
···
415
let leaves_list = Cid.Set.to_list leaves in
416
let%lwt leaves_bm = Store.get_blocks t.blockstore leaves_list in
417
if leaves_bm.missing <> [] then failwith "missing mst leaf blocks" ;
418
-
let leaves_nodes = Storage.Block_map.entries leaves_bm.blocks in
419
match leaves_nodes with
420
| [] ->
421
(* with Done, we don't care about the first pair element *)
···
432
(fun (acc, nxt, lvs) cid ->
433
let bytes =
434
(* we should be safe to do this since we just got the cids from the blockmap *)
435
-
Storage.Block_map.get cid bm.blocks |> Option.get
436
in
437
let node = decode_block_raw bytes in
438
let nxt' =
···
470
Lwt.return_some (Obj.magic (), Done)
471
in
472
Lwt_seq.unfold_lwt step init_state
473
end
···
1
+
open Storage
2
module StringMap = Dag_cbor.StringMap
3
4
type node_raw =
···
38
39
and entry =
40
{layer: int; key: string; value: Cid.t; right: node option Lwt.t Lazy.t}
41
+
42
+
type node_or_entry = Node of node | Entry of entry
43
44
let ( let*? ) lazy_opt_lwt f =
45
let%lwt result = Lazy.force lazy_opt_lwt in
···
88
node.entries <- node.entries @ [entry] ;
89
Lwt.return node )
90
91
+
(* returns the index of the first entry in an interspersed list that's gte a given key *)
92
+
let find_gte_entry_index entries key : int =
93
+
let rec aux entries index =
94
match entries with
95
| [] ->
96
+
(* will be entries length when not found *)
97
+
index
98
+
| e :: es -> (
99
+
match e with
100
+
| Entry entry when entry.key >= key ->
101
+
index
102
+
| _ ->
103
+
aux es (index + 1) )
104
in
105
+
aux entries 0
106
107
+
(* produces a cid and cbor-encoded bytes for a given tree *)
108
+
let serialize node : (Cid.t * bytes) Lwt.t =
109
+
let sorted_entries =
110
+
List.sort (fun a b -> String.compare a.key b.key) node.entries
111
+
in
112
+
let rec aux node =
113
+
let%lwt left =
114
+
node.left
115
+
>>? function
116
+
| Some l ->
117
+
let%lwt cid, _ = aux l in
118
+
Lwt.return_some cid
119
+
| None ->
120
+
Lwt.return_none
121
+
in
122
+
let last_key = ref "" in
123
+
let%lwt mst_entries =
124
+
Lwt_list.map_s
125
+
(fun entry ->
126
+
let%lwt right =
127
+
entry.right
128
+
>>? function
129
+
| Some r ->
130
+
let%lwt cid, _ = aux r in
131
+
Lwt.return (Some cid)
132
+
| None ->
133
+
Lwt.return None
134
+
in
135
+
let prefix_len = Util.shared_prefix_length !last_key entry.key in
136
+
last_key := entry.key ;
137
+
Lwt.return
138
+
{ k=
139
+
Bytes.of_string
140
+
(String.sub entry.key prefix_len
141
+
(String.length entry.key - prefix_len) )
142
+
; p= prefix_len
143
+
; v= entry.value
144
+
; t= right } )
145
+
node.entries
146
+
in
147
+
let encoded = Dag_cbor.encode (encode_node_raw {l= left; e= mst_entries}) in
148
+
let cid = Cid.create Dcbor encoded in
149
+
Lwt.return (cid, encoded)
150
+
in
151
+
aux {node with entries= sorted_entries}
152
153
+
module Make (Store : Writable_blockstore) = struct
154
type bs = Store.t
155
156
type t = {blockstore: bs; root: Cid.t}
···
209
| _ ->
210
raise (Invalid_argument "invalid block")
211
212
+
(* retrieves a raw node by cid *)
213
let retrieve_node_raw t cid : node_raw option Lwt.t =
214
match%lwt Store.get_bytes t.blockstore cid with
215
| Some bytes ->
···
217
| None ->
218
Lwt.return_none
219
220
+
(* retrieves & hydrates a node by cid *)
221
let rec retrieve_node t cid : node option Lwt.t =
222
match%lwt retrieve_node_raw t cid with
223
| Some raw ->
···
225
| None ->
226
Lwt.return_none
227
228
+
(* lazy version of retrieve_node *)
229
and retrieve_node_lazy t cid = lazy (retrieve_node t cid)
230
231
(* hydrates a raw node *)
···
304
traverse t (fun path cid -> ignore (StringMap.add path cid map))
305
in
306
Lwt.return map
307
308
(* returns cids and blocks that form the path from a given node to a given entry *)
309
let rec path_to_entry t node key : (Cid.t * bytes) list Lwt.t =
310
let%lwt root_bytes = Store.get_bytes t.blockstore node in
311
+
let%lwt root_raw =
312
match root_bytes with
313
| None ->
314
Lwt.return_none
315
| Some bytes ->
316
Lwt.return_some (decode_block_raw bytes)
317
in
318
+
let%lwt root =
319
+
match root_raw with
320
+
| None ->
321
+
Lwt.return_none
322
+
| Some root ->
323
+
hydrate_node t root |> Lwt.map Option.some
324
+
in
325
(* if there is a left child, try to find a path through the left subtree *)
326
let%lwt path_through_left =
327
+
match root_raw with
328
| None ->
329
Lwt.return_some []
330
+
| Some raw -> (
331
+
match raw.l with
332
| None ->
333
Lwt.return_none
334
| Some left -> (
···
337
Lwt.return_none
338
| path ->
339
(* Option.get is safe because root is Some only when root_bytes is Some *)
340
+
Lwt.return_some (path @ [(node, Option.get root_bytes)]) ) )
341
in
342
match path_through_left with
343
| Some path ->
344
Lwt.return path
345
| None -> (
346
(* if a left subtree path couldn't be found, find the entry whose right subtree this key would belong to *)
347
+
(* this branch is only reached when root/root_raw/root_bytes are not None;
348
+
if they were, path_through_left would be Some [] *)
349
+
let entries = (Option.get root).entries in
350
let entries_len = List.length entries in
351
let entry_index =
352
+
match List.find_index (fun e -> e.key >= key) entries with
353
| Some index ->
354
index
355
| None ->
356
entries_len
357
in
358
+
(* path_through_left is None -> root_bytes is Some *)
359
+
let path_tail = [(node, Option.get root_bytes)] in
360
(* entry_index here is actually the entry to the right of the subtree the key would belong to *)
361
match entry_index with
362
| _
363
(* because entries[entry_index] might turn out to be the entry we're looking for *)
364
when entry_index < entries_len
365
+
&& (List.nth entries entry_index).key = key ->
366
Lwt.return path_tail
367
| _ -> (
368
(* otherwise, we continue down the right subtree of the entry before entry_index *)
369
+
(* path_through_left is None -> root_raw is Some *)
370
+
match Util.last (Option.get root_raw).e with
371
+
| Some last when last.t <> None ->
372
let%lwt path_through_right =
373
+
(* when last.t <> None *)
374
path_to_entry t (Option.get last.t) key
375
in
376
Lwt.return (path_through_right @ path_tail)
···
407
let leaves_list = Cid.Set.to_list leaves in
408
let%lwt leaves_bm = Store.get_blocks t.blockstore leaves_list in
409
if leaves_bm.missing <> [] then failwith "missing mst leaf blocks" ;
410
+
let leaves_nodes = Block_map.entries leaves_bm.blocks in
411
match leaves_nodes with
412
| [] ->
413
(* with Done, we don't care about the first pair element *)
···
424
(fun (acc, nxt, lvs) cid ->
425
let bytes =
426
(* we should be safe to do this since we just got the cids from the blockmap *)
427
+
Block_map.get cid bm.blocks |> Option.get
428
in
429
let node = decode_block_raw bytes in
430
let nxt' =
···
462
Lwt.return_some (Obj.magic (), Done)
463
in
464
Lwt_seq.unfold_lwt step init_state
465
+
466
+
(* returns all mst nodes needed to prove the value of a given key *)
467
+
let rec proof_for_key t root key : Block_map.t Lwt.t =
468
+
let e_rev = List.rev root.entries in
469
+
(* iterate in reverse because if the key doesn't exist at this level,
470
+
we need to search the "previous" node's right subtree *)
471
+
let rec find_proof entries_rev =
472
+
match entries_rev with
473
+
| [] ->
474
+
Lwt.return Block_map.empty
475
+
| e :: rest -> (
476
+
if e.key > key then find_proof rest
477
+
else if e.key = key then Lwt.return Block_map.empty
478
+
else
479
+
let*? right = e.right in
480
+
match right with
481
+
| Some r ->
482
+
proof_for_key t r key
483
+
| None ->
484
+
Lwt.return Block_map.empty )
485
+
in
486
+
let%lwt bm = find_proof e_rev in
487
+
let%lwt root_cid, root_bytes = serialize root in
488
+
Lwt.return (Block_map.set root_cid root_bytes bm)
489
+
490
+
(* returns all mst nodes needed to prove the value of a given key's left sibling *)
491
+
let rec proof_for_left_sibling t root key : Block_map.t Lwt.t =
492
+
let e_rev = List.rev root.entries in
493
+
(* iterate in reverse for the same reason as proof_for_key *)
494
+
let rec find_proof entries_rev =
495
+
match entries_rev with
496
+
| [] ->
497
+
Lwt.return Block_map.empty
498
+
| e :: rest -> (
499
+
if e.key >= key then find_proof rest
500
+
else
501
+
let*? right = e.right in
502
+
match right with
503
+
| Some r ->
504
+
proof_for_left_sibling t r key
505
+
| None ->
506
+
Lwt.return Block_map.empty )
507
+
in
508
+
let%lwt bm = find_proof e_rev in
509
+
let%lwt root_cid, root_bytes = serialize root in
510
+
Lwt.return (Block_map.set root_cid root_bytes bm)
511
+
512
+
(* returns all mst nodes needed to prove the value of a given key's right sibling *)
513
+
let rec proof_for_right_sibling t root key : Block_map.t Lwt.t =
514
+
(* unlike the other two, this doesn't iterate in reverse
515
+
because we can stop as soon as we're past the key *)
516
+
let rec find_proof ?(prev = None) entries =
517
+
match entries with
518
+
| [] -> (
519
+
(* end of entries, right sibling must be in the last entry's right subtree *)
520
+
match prev with
521
+
| Some e -> (
522
+
let*? right = e.right in
523
+
match right with
524
+
| Some r ->
525
+
proof_for_right_sibling t r key
526
+
| None ->
527
+
Lwt.return Block_map.empty )
528
+
| None ->
529
+
Lwt.return Block_map.empty )
530
+
| e :: rest ->
531
+
if e.key > key then
532
+
(* we're past target key; right sibling is in previous entry's right subtree *)
533
+
match prev with
534
+
| Some p -> (
535
+
let*? right = p.right in
536
+
match right with
537
+
| Some r ->
538
+
proof_for_right_sibling t r key
539
+
(* I don't think this should ever happen? *)
540
+
| None ->
541
+
Lwt.return Block_map.empty )
542
+
(* first entry is already greater than key; we're inside the sibling *)
543
+
| None ->
544
+
Lwt.return Block_map.empty
545
+
else if e.key = key then
546
+
(* found the entry, right sibling is in its right subtree *)
547
+
let*? right = e.right in
548
+
match right with
549
+
| Some r ->
550
+
proof_for_right_sibling t r key
551
+
| None ->
552
+
Lwt.return Block_map.empty
553
+
else (* e.key < key, keep searching *)
554
+
find_proof ~prev:(Some e) rest
555
+
in
556
+
let%lwt bm = find_proof root.entries in
557
+
let%lwt root_cid, root_bytes = serialize root in
558
+
Lwt.return (Block_map.set root_cid root_bytes bm)
559
+
560
+
(* a covering proof is all mst nodes needed to prove the value of a given leaf
561
+
and its siblings to its immediate right and left (if applicable) *)
562
+
let get_covering_proof t root key : Block_map.t Lwt.t =
563
+
let%lwt proofs =
564
+
Lwt.all
565
+
[ proof_for_key t root key
566
+
; proof_for_left_sibling t root key
567
+
; proof_for_right_sibling t root key ]
568
+
in
569
+
Lwt.return
570
+
(List.fold_left
571
+
(fun acc proof -> Block_map.merge acc proof)
572
+
Block_map.empty proofs )
573
end