package tezos-protocol-015-PtLimaPt

  1. Overview
  2. Docs
package tezos-protocol-015-PtLimaPt
Legend:
Page
Library
Module
Module type
Parameter
Class
Class type
Source

Source file bounded_history_repr.ml

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
(*****************************************************************************)
(*                                                                           *)
(* Open Source License                                                       *)
(* Copyright (c) 2022 Nomadic Labs <contact@nomadic-labs.com>                *)
(*                                                                           *)
(* Permission is hereby granted, free of charge, to any person obtaining a   *)
(* copy of this software and associated documentation files (the "Software"),*)
(* to deal in the Software without restriction, including without limitation *)
(* the rights to use, copy, modify, merge, publish, distribute, sublicense,  *)
(* and/or sell copies of the Software, and to permit persons to whom the     *)
(* Software is furnished to do so, subject to the following conditions:      *)
(*                                                                           *)
(* The above copyright notice and this permission notice shall be included   *)
(* in all copies or substantial portions of the Software.                    *)
(*                                                                           *)
(* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR*)
(* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  *)
(* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL   *)
(* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER*)
(* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING   *)
(* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER       *)
(* DEALINGS IN THE SOFTWARE.                                                 *)
(*                                                                           *)
(*****************************************************************************)

module type NAME = sig
  val name : string
end

module type KEY = sig
  type t

  val compare : t -> t -> int

  val pp : Format.formatter -> t -> unit

  val encoding : t Data_encoding.t
end

module type VALUE = sig
  type t

  val equal : t -> t -> bool

  val pp : Format.formatter -> t -> unit

  val encoding : t Data_encoding.t
end

module type S = sig
  type t

  type key

  type value

  val empty : capacity:int64 -> t

  val encoding : t Data_encoding.t

  val pp : Format.formatter -> t -> unit

  val find : key -> t -> value option

  type error +=
    | Key_bound_to_different_value of {
        key : key;
        existing_value : value;
        given_value : value;
      }

  val remember : key -> value -> t -> t tzresult

  module Internal_for_tests : sig
    val empty : capacity:int64 -> next_index:int64 -> t

    val keys : t -> key list
  end
end

module Make (Name : NAME) (Key : KEY) (Value : VALUE) :
  S with type key = Key.t and type value = Value.t = struct
  type key = Key.t

  type value = Value.t

  module Int64_map = Map.Make (Int64)
  module Map = Map.Make (Key)

  type t = {
    events : value Map.t;
        (** Values stored in the structure, indexes with the keys. *)
    sequence : key Int64_map.t;
        (** An additional map from int64 indexes to keys, to be able
            to remove old entries when the structure is full.  *)
    capacity : int64;
        (** The max number of the entries in the structure. Once the maximum size
            is reached, older entries are deleted to free space for new ones. *)
    next_index : int64;
        (** The index to use for the next entry to add in the structure. *)
    oldest_index : int64;
        (** The oldest index of the (oldest) entry that has been added to the
            data structure. If the structure is empty, [oldest_index] is
            equal to [next_index]. *)
    size : int64;
        (** Counts the number of entries that are stored in history. It
            satisfies the invariant: `0 <= size <= capacity` *)
  }

  let encoding : t Data_encoding.t =
    let open Data_encoding in
    let events_encoding =
      Data_encoding.conv
        Map.bindings
        (fun l -> Map.add_seq (List.to_seq l) Map.empty)
        Data_encoding.(list (tup2 Key.encoding Value.encoding))
    in
    let sequence_encoding =
      conv
        Int64_map.bindings
        (List.fold_left (fun m (k, v) -> Int64_map.add k v m) Int64_map.empty)
        (list (tup2 int64 Key.encoding))
    in
    conv
      (fun {events; sequence; capacity; next_index; oldest_index; size} ->
        (events, sequence, capacity, next_index, oldest_index, size))
      (fun (events, sequence, capacity, next_index, oldest_index, size) ->
        {events; sequence; capacity; next_index; oldest_index; size})
      (obj6
         (req "events" events_encoding)
         (req "sequence" sequence_encoding)
         (req "capacity" int64)
         (req "next_index" int64)
         (req "oldest_index" int64)
         (req "size" int64))

  let pp fmt {events; sequence; capacity; size; oldest_index; next_index} =
    Map.bindings events |> fun bindings ->
    Int64_map.bindings sequence |> fun sequence_bindings ->
    let pp_binding fmt (hash, history_proof) =
      Format.fprintf fmt "@[%a -> %a@;@]" Key.pp hash Value.pp history_proof
    in
    let pp_sequence_binding fmt (counter, hash) =
      Format.fprintf fmt "@[%s -> %a@;@]" (Int64.to_string counter) Key.pp hash
    in
    Format.fprintf
      fmt
      "@[<hov 2>History:@;\
      \ { capacity: %Ld;@;\
      \ current size: %Ld;@;\
      \ oldest index: %Ld;@;\
      \ next_index : %Ld;@;\
      \ bindings: %a;@;\
      \ sequence: %a; }@]"
      capacity
      size
      oldest_index
      next_index
      (Format.pp_print_list pp_binding)
      bindings
      (Format.pp_print_list pp_sequence_binding)
      sequence_bindings

  let empty ~capacity =
    let next_index = 0L in
    {
      events = Map.empty;
      sequence = Int64_map.empty;
      capacity;
      next_index;
      oldest_index = next_index;
      size = 0L;
    }

  type error +=
    | Key_bound_to_different_value of {
        key : key;
        existing_value : value;
        given_value : value;
      }

  let () =
    assert (not (String.equal Name.name "")) ;
    register_error_kind
      `Temporary
      ~id:
        (Format.sprintf
           "Bounded_history_repr.%s.key_bound_to_different_value"
           Name.name)
      ~title:(Name.name ^ ": Key already bound to a different value.")
      ~description:
        (Name.name
       ^ ": Remember called with a key that is already bound to a different\n\
         \        value.")
      Data_encoding.(
        obj3
          (req "key" Key.encoding)
          (req "existing_value" Value.encoding)
          (req "given_value" Value.encoding))
      (function
        | Key_bound_to_different_value {key; existing_value; given_value} ->
            Some (key, existing_value, given_value)
        | _ -> None)
      (fun (key, existing_value, given_value) ->
        Key_bound_to_different_value {key; existing_value; given_value})

  let remember key value t =
    let open Tzresult_syntax in
    if Compare.Int64.(t.capacity <= 0L) then return t
    else
      match Map.find key t.events with
      | Some value' when not (Value.equal value value') ->
          error
          @@ Key_bound_to_different_value
               {key; existing_value = value'; given_value = value}
      | _ -> (
          let events = Map.add key value t.events in
          let current_index = t.next_index in
          let next_index = Int64.succ current_index in
          let t =
            {
              events;
              sequence = Int64_map.add current_index key t.sequence;
              capacity = t.capacity;
              next_index;
              oldest_index = t.oldest_index;
              size = Int64.succ t.size;
            }
          in
          (* A negative size means that [t.capacity] is set to [Int64.max_int]
             and that the structure is full, so adding a new entry makes the size
             overflows. In this case, we remove an element in the else branch to
             keep the size of the structure equal to [Int64.max_int] at most. *)
          if Compare.Int64.(t.size > 0L && t.size <= t.capacity) then return t
          else
            let l = t.oldest_index in
            match Int64_map.find l t.sequence with
            | None ->
                (* If t.size > t.capacity > 0, there is necessarily
                   an entry whose index is t.oldest_index in [sequence]. *)
                assert false
            | Some h ->
                let sequence = Int64_map.remove l t.sequence in
                let events = Map.remove h events in
                return
                  {
                    next_index = t.next_index;
                    capacity = t.capacity;
                    size = t.capacity;
                    oldest_index = Int64.succ t.oldest_index;
                    sequence;
                    events;
                  })

  let find key t = Map.find_opt key t.events

  module Internal_for_tests = struct
    let empty ~capacity ~next_index =
      {(empty ~capacity) with next_index; oldest_index = next_index}

    let keys {sequence; oldest_index; _} =
      let l = Int64_map.bindings sequence in
      (* All entries with an index greater than oldest_index are well ordered.
         There are put in the [lp] list. Entries with an index smaller than
         oldest_index are also well ordered, but they should come after
         elements in [lp]. This happens in theory when the index reaches
         max_int and then overflows. *)
      let ln, lp =
        List.partition_map
          (fun (n, h) ->
            if Compare.Int64.(n < oldest_index) then Left h else Right h)
          l
      in
      (* do a tail recursive concatenation lp @ ln *)
      List.rev_append (List.rev lp) ln
  end
end