From 1fb6d98882aecaefa85ca80e8738c753bfc5464c Mon Sep 17 00:00:00 2001
From: Eugen Zalinescu <eugen.zalinescu@nomadic-labs.com>
Date: Thu, 1 Dec 2022 15:46:09 +0100
Subject: [PATCH 01/10] Proto/Dal: make minor doc-string edits

---
 src/proto_alpha/lib_protocol/raw_context.ml  |  6 ++---
 src/proto_alpha/lib_protocol/raw_context.mli | 23 ++++++++++----------
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/src/proto_alpha/lib_protocol/raw_context.ml b/src/proto_alpha/lib_protocol/raw_context.ml
index 77d3cf56ab1c..759e5cdf5b4f 100644
--- a/src/proto_alpha/lib_protocol/raw_context.ml
+++ b/src/proto_alpha/lib_protocol/raw_context.ml
@@ -1702,13 +1702,13 @@ module Dal = struct
         let slot_index = Slot_repr.to_int slot in
         (* An optimisation could be to return only [pkh_to_shards] map
            because the second one is not used. This can be done later
-           on if it is a good optimisation. *)
+           on, if it is a good optimisation. *)
         let committee = update_committee committee pkh ~slot_index ~power:1 in
         compute_power (index - 1) committee
     in
     (* This committee is an intermediate to compute the final DAL
-       commitee. This one only projects the Tenderbake committee into
-       the DAL committee. The next one reorder the slots so that they
+       committee. This one only projects the Tenderbake committee into
+       the DAL committee. The next one reorders the slots so that they
        are grouped by public key hash. *)
     compute_power (number_of_shards - 1) empty_dal_committee
     >>=? fun unordered_committee ->
diff --git a/src/proto_alpha/lib_protocol/raw_context.mli b/src/proto_alpha/lib_protocol/raw_context.mli
index c181e1cf1296..74998fff5b8b 100644
--- a/src/proto_alpha/lib_protocol/raw_context.mli
+++ b/src/proto_alpha/lib_protocol/raw_context.mli
@@ -427,25 +427,26 @@ module Dal : sig
 
   (** The DAL committee is a subset of the Tenderbake committee.  A
      shard from [0;number_of_shards] is associated to a public key
-     hash. For efficiency reasons, the committee is two-folds: a
-     mapping public key hash to shards and shards to public key
-     hashes. The DAL committee ensures the shards associated to the
+     hash. For efficiency reasons, the committee is both:
+     a mapping from public key hashes to shards and
+     a mapping from shards to public key hashes.
+     The DAL committee ensures the shards associated to the
      same public key hash are contiguous. The list of shards is
      represented as two natural numbers [(initial, power)] which
      encodes the list of shards:
-     [initial;initial + 1;...;initial + power - 1].
+     [initial; initial + 1; ... ; initial + power - 1].
 
       This data-type ensures the following invariants:
 
       - \forall pkh shard, find pkh_to_shards pkh = Some (start,n) ->
-     \forall i, i \in [start; start + n -1] -> find shard_to_pkh shard
+     \forall i, i \in [start; start + n - 1] -> find shard_to_pkh i
      = Some pkh
 
       - forall pkh shard, find shard_to_pkh shard = Some pkh ->
      \exists (start,n), find pkh_to_shards pkh = Some (start,n) /\
-     start <= shard <= start + n -1
+     start <= shard <= start + n - 1
 
-      - Given an attestor, all its shards assignement are contiguous
+      - Given an attestor, all its shard assignments are contiguous
      *)
   type committee = {
     pkh_to_shards :
@@ -456,12 +457,12 @@ module Dal : sig
   (** [compute_committee ctxt pkh_from_tenderbake_slot] computes the
      DAL committee using the [pkh_from_tenderbake_slot] function. This
      functions takes into account the fact that the DAL committee and
-     the Tenderbake committee may have different size. If the DAL
+     the Tenderbake committee may have different sizes. If the DAL
      committee is smaller, then we simply take a projection of the
      Tenderbake committee for the first [n] slots. If the DAL
-     committee is larger, shards are computed moduloe the Tenderbake
-     committee. Slots assignements are reordered for a given a public
-     key hash, to ensure all the slots (or shards in the context of
+     committee is larger, shards are computed modulo the Tenderbake
+     committee. Slots assignments are reordered for a given a public
+     key hash to ensure all the slots (or shards in the context of
      DAL) shards are contiguous (see {!type:committee}). *)
   val compute_committee :
     t ->
-- 
GitLab


From 092423b24fce3eaab33207820d93ee7bcc421d13 Mon Sep 17 00:00:00 2001
From: Eugen Zalinescu <eugen.zalinescu@nomadic-labs.com>
Date: Thu, 1 Dec 2022 16:02:16 +0100
Subject: [PATCH 02/10] Proto/Dal: rename functions for clarity

---
 src/proto_alpha/lib_protocol/alpha_context.mli |  2 +-
 src/proto_alpha/lib_protocol/dal_apply.ml      |  2 +-
 src/proto_alpha/lib_protocol/raw_context.ml    |  4 ++--
 src/proto_alpha/lib_protocol/raw_context.mli   | 12 ++++++------
 4 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/proto_alpha/lib_protocol/alpha_context.mli b/src/proto_alpha/lib_protocol/alpha_context.mli
index 073242aeef40..0f5a2ee5c2d7 100644
--- a/src/proto_alpha/lib_protocol/alpha_context.mli
+++ b/src/proto_alpha/lib_protocol/alpha_context.mli
@@ -2956,7 +2956,7 @@ module Dal : sig
     val shards_of_attestor :
       context -> attestor:public_key_hash -> shard_index list option
 
-    val record_available_shards : context -> t -> int list -> context
+    val record_attested_shards : context -> t -> int list -> context
 
     type committee = {
       pkh_to_shards : (shard_index * int) Signature.Public_key_hash.Map.t;
diff --git a/src/proto_alpha/lib_protocol/dal_apply.ml b/src/proto_alpha/lib_protocol/dal_apply.ml
index 25a71055138e..6ad45b9824b5 100644
--- a/src/proto_alpha/lib_protocol/dal_apply.ml
+++ b/src/proto_alpha/lib_protocol/dal_apply.ml
@@ -79,7 +79,7 @@ let apply_attestation ctxt op =
       let level = Level.current ctxt in
       error (Dal_data_availibility_attestor_not_in_committee {attestor; level})
   | Some shards ->
-      Ok (Dal.Attestation.record_available_shards ctxt attestation shards)
+      Ok (Dal.Attestation.record_attested_shards ctxt attestation shards)
 
 let validate_publish_slot_header ctxt operation =
   assert_dal_feature_enabled ctxt >>? fun () ->
diff --git a/src/proto_alpha/lib_protocol/raw_context.ml b/src/proto_alpha/lib_protocol/raw_context.ml
index 759e5cdf5b4f..6bc603a251ae 100644
--- a/src/proto_alpha/lib_protocol/raw_context.ml
+++ b/src/proto_alpha/lib_protocol/raw_context.ml
@@ -1600,11 +1600,11 @@ module Dal = struct
       (fun (length, slot_header) ->
         Dal_register_invalid_slot_header {length; slot_header})
 
-  let record_available_shards ctxt slots shards =
+  let record_attested_shards ctxt attestation shards =
     let dal_attestation_slot_accountability =
       Dal_attestation_repr.Accountability.record_shards_availability
         ctxt.back.dal_attestation_slot_accountability
-        slots
+        attestation
         shards
     in
     {ctxt with back = {ctxt.back with dal_attestation_slot_accountability}}
diff --git a/src/proto_alpha/lib_protocol/raw_context.mli b/src/proto_alpha/lib_protocol/raw_context.mli
index 74998fff5b8b..16ab92f48169 100644
--- a/src/proto_alpha/lib_protocol/raw_context.mli
+++ b/src/proto_alpha/lib_protocol/raw_context.mli
@@ -394,12 +394,12 @@ module Sc_rollup_in_memory_inbox : sig
 end
 
 module Dal : sig
-  (** [record_available_shards ctxt slots shards] records that the
-     list of shards [shards] were declared available. The function
-     assumes that a shard belongs to the interval [0; number_of_shards
-     - 1]. Otherwise, for each shard outside this interval, it is a
-     no-op. *)
-  val record_available_shards : t -> Dal_attestation_repr.t -> int list -> t
+  (** [record_attested_shards ctxt attestation shards] records that the
+     list of shards [shards] were attested (declared available by some
+     attestor). The function assumes that a shard belongs to the
+     interval [0; number_of_shards - 1]. Otherwise, for each shard
+     outside this interval, it is a no-op. *)
+  val record_attested_shards : t -> Dal_attestation_repr.t -> int list -> t
 
   (** [register_slot_header ctxt slot_header] returns a new context
      where the new candidate [slot] have been taken into
-- 
GitLab


From c9006774e6d8d59cb4ecdd980a3ca9840417c17c Mon Sep 17 00:00:00 2001
From: Eugen Zalinescu <eugen.zalinescu@nomadic-labs.com>
Date: Thu, 1 Dec 2022 17:11:35 +0100
Subject: [PATCH 03/10] Proto/Dal: make minor edits for readability

---
 .../lib_protocol/dal_attestation_repr.ml         | 16 ++++++++++------
 .../lib_protocol/dal_attestation_repr.mli        |  6 +++---
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/src/proto_alpha/lib_protocol/dal_attestation_repr.ml b/src/proto_alpha/lib_protocol/dal_attestation_repr.ml
index a3b68922fada..afdd35ac4d8b 100644
--- a/src/proto_alpha/lib_protocol/dal_attestation_repr.ml
+++ b/src/proto_alpha/lib_protocol/dal_attestation_repr.ml
@@ -39,9 +39,9 @@
    representation. Hence, if there are [256] slots, and [2] are not
    attested, this representation will be of size [32] bits + [16] bits
    = [48] bits which is better than [256] bits. *)
-type t = Bitset.t
 
-type attested_slots = t
+(* A set of (attested) slot indexes. *)
+type t = Bitset.t
 
 type operation = {
   attestor : Signature.Public_key_hash.t;
@@ -96,11 +96,15 @@ module Shard_map = Map.Make (struct
 end)
 
 module Accountability = struct
+  type attested_slots = t
+
   (* DAL/FIXME https://gitlab.com/tezos/tezos/-/issues/3109
 
      Think hard about this data structure and whether it needs to be
      optimized.
   *)
+
+  (* A list of set of shard indexes (a set of shards per slot) *)
   type t = Bitset.t list
 
   let init ~length =
@@ -120,15 +124,15 @@ module Accountability = struct
       bitset
       shards
 
-  let record_shards_availability shard_bitset_per_slot slots shards =
+  let record_shards_availability shard_bitset_per_slot attested_slots shards =
     List.mapi
       (fun slot bitset ->
-        match Bitset.mem slots slot with
+        match Bitset.mem attested_slots slot with
         | Error _ ->
             (* slot index is above the length provided at initialisation *)
             bitset
-        | Ok slot_available ->
-            if slot_available then record_slot_shard_availability bitset shards
+        | Ok slot_attested ->
+            if slot_attested then record_slot_shard_availability bitset shards
             else bitset)
       shard_bitset_per_slot
 
diff --git a/src/proto_alpha/lib_protocol/dal_attestation_repr.mli b/src/proto_alpha/lib_protocol/dal_attestation_repr.mli
index 7d1ebed02e72..5975b03a730b 100644
--- a/src/proto_alpha/lib_protocol/dal_attestation_repr.mli
+++ b/src/proto_alpha/lib_protocol/dal_attestation_repr.mli
@@ -44,8 +44,6 @@
 
 type t
 
-type attested_slots = t
-
 (** The shape of Dal attestation operations injected by delegates. *)
 type operation = {
   attestor : Signature.Public_key_hash.t;
@@ -69,7 +67,7 @@ val empty : t
 val is_attested : t -> Dal_slot_repr.Index.t -> bool
 
 (** [commit slot_attestation index] commits into [slot_attestation]
-   that the [index] is available. *)
+   that the slot [index] is available. *)
 val commit : t -> Dal_slot_repr.Index.t -> t
 
 (** [occupied_size_in_bits slot_attestation] returns the size in bits of an attestation. *)
@@ -95,6 +93,8 @@ module Shard_map : Map.S with type key = shard_index
    This information will be used at the end of block finalisation to
    have the protocol declaring whether the slot is available.  *)
 module Accountability : sig
+  type attested_slots = t
+
   (** The data-structure used to record the shards-slots availability. *)
   type t
 
-- 
GitLab


From f0c93b420db9eeb23ad751f7f8a1f586bd901b8b Mon Sep 17 00:00:00 2001
From: Eugen Zalinescu <eugen.zalinescu@nomadic-labs.com>
Date: Tue, 6 Dec 2022 12:44:28 +0100
Subject: [PATCH 04/10] Proto/Plugin: default level for dal_shards RPC is
 current level

---
 src/proto_alpha/lib_plugin/RPC.ml | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/proto_alpha/lib_plugin/RPC.ml b/src/proto_alpha/lib_plugin/RPC.ml
index 8302e417096d..b40051a5d75c 100644
--- a/src/proto_alpha/lib_plugin/RPC.ml
+++ b/src/proto_alpha/lib_plugin/RPC.ml
@@ -2411,7 +2411,9 @@ module Dal = struct
 
     let shards =
       RPC_service.get_service
-        ~description:"Get the shard assignements for a given level"
+        ~description:
+          "Get the shard assignements for a given level (the default is the \
+           current level)"
         ~query:shards_query
         ~output:
           Data_encoding.(
@@ -2433,7 +2435,7 @@ module Dal = struct
 
   let register_shards () =
     Registration.register0 ~chunked:true S.shards @@ fun ctxt level () ->
-    let level = Option.value level ~default:(Raw_level.of_int32_exn 0l) in
+    let level = Option.value level ~default:(Level.current ctxt).level in
     Dal_services.shards ctxt ~level
 
   let register () =
-- 
GitLab


From 15294124aa112e51e825d9e53dcc0723bff502b8 Mon Sep 17 00:00:00 2001
From: Eugen Zalinescu <eugen.zalinescu@nomadic-labs.com>
Date: Mon, 5 Dec 2022 15:00:24 +0100
Subject: [PATCH 05/10] Proto/Dal: refactor to eliminate duplicate code

---
 src/proto_alpha/lib_protocol/dal_apply.ml     | 24 +++++++++----------
 src/proto_alpha/lib_protocol/dal_apply.mli    |  3 +++
 src/proto_alpha/lib_protocol/dal_services.ml  | 10 ++------
 .../validate/generator_descriptors.ml         | 10 +-------
 4 files changed, 18 insertions(+), 29 deletions(-)

diff --git a/src/proto_alpha/lib_protocol/dal_apply.ml b/src/proto_alpha/lib_protocol/dal_apply.ml
index 6ad45b9824b5..b4e265918217 100644
--- a/src/proto_alpha/lib_protocol/dal_apply.ml
+++ b/src/proto_alpha/lib_protocol/dal_apply.ml
@@ -152,21 +152,21 @@ let finalisation ctxt =
       Dal.Slot.finalize_pending_slot_headers ctxt
       >|=? fun (ctxt, attestation) -> (ctxt, Some attestation))
 
+let compute_committee ctxt level =
+  assert_dal_feature_enabled ctxt >>?= fun () ->
+  let pkh_from_tenderbake_slot slot =
+    Stake_distribution.slot_owner ctxt level slot
+    >|=? fun (ctxt, consensus_pk1) -> (ctxt, consensus_pk1.delegate)
+  in
+  (* This committee is cached because it is the one we will use
+     for the validation of the DAL attestations. *)
+  Alpha_context.Dal.Attestation.compute_committee ctxt pkh_from_tenderbake_slot
+
 let initialisation ctxt ~level =
   let open Lwt_result_syntax in
   only_if_dal_feature_enabled
     ctxt
     ~default:(fun ctxt -> return ctxt)
     (fun ctxt ->
-      let pkh_from_tenderbake_slot slot =
-        Stake_distribution.slot_owner ctxt level slot
-        >|=? fun (ctxt, consensus_pk1) -> (ctxt, consensus_pk1.delegate)
-      in
-      (* This committee is cached because it is the one we will use
-         for the validation of the DAL attestations. *)
-      let* committee =
-        Alpha_context.Dal.Attestation.compute_committee
-          ctxt
-          pkh_from_tenderbake_slot
-      in
-      return (Alpha_context.Dal.Attestation.init_committee ctxt committee))
+      let+ committee = compute_committee ctxt level in
+      Alpha_context.Dal.Attestation.init_committee ctxt committee)
diff --git a/src/proto_alpha/lib_protocol/dal_apply.mli b/src/proto_alpha/lib_protocol/dal_apply.mli
index 28daea642838..5ff80c0a65dc 100644
--- a/src/proto_alpha/lib_protocol/dal_apply.mli
+++ b/src/proto_alpha/lib_protocol/dal_apply.mli
@@ -63,3 +63,6 @@ val finalisation : t -> (t * Dal.Attestation.t option) tzresult Lwt.t
    in memory so that every time we need to use this committee, there
    is no need to recompute it again. *)
 val initialisation : t -> level:Level.t -> t tzresult Lwt.t
+
+(** [compute_committee ctxt level] computes the DAL committee for [level]. *)
+val compute_committee : t -> Level.t -> Dal.Attestation.committee tzresult Lwt.t
diff --git a/src/proto_alpha/lib_protocol/dal_services.ml b/src/proto_alpha/lib_protocol/dal_services.ml
index 660f6783ec7f..67ec5d301834 100644
--- a/src/proto_alpha/lib_protocol/dal_services.ml
+++ b/src/proto_alpha/lib_protocol/dal_services.ml
@@ -37,13 +37,7 @@ let shards ctxt ~level =
   let open Dal.Attestation in
   assert_dal_feature_enabled ctxt >>?= fun () ->
   let level = Level.from_raw ctxt level in
-  let pkh_from_tenderbake_slot slot =
-    Stake_distribution.slot_owner ctxt level slot
-    >|=? fun (ctxt, consensus_key) -> (ctxt, consensus_key.delegate)
-  in
   (* We do not cache this committee. This function being used by RPCs
      to know the DAL committee at some particular level. *)
-  let* committee =
-    Dal.Attestation.compute_committee ctxt pkh_from_tenderbake_slot
-  in
-  Signature.Public_key_hash.Map.bindings committee.pkh_to_shards |> return
+  let+ committee = Dal_apply.compute_committee ctxt level in
+  Signature.Public_key_hash.Map.bindings committee.pkh_to_shards
diff --git a/src/proto_alpha/lib_protocol/test/integration/validate/generator_descriptors.ml b/src/proto_alpha/lib_protocol/test/integration/validate/generator_descriptors.ml
index 170f0435c8da..d79b6d0ea3a8 100644
--- a/src/proto_alpha/lib_protocol/test/integration/validate/generator_descriptors.ml
+++ b/src/proto_alpha/lib_protocol/test/integration/validate/generator_descriptors.ml
@@ -631,15 +631,7 @@ let endorsement_descriptor =
 let dal_slot_availibility ctxt delegate =
   let open Lwt_result_syntax in
   let level = Alpha_context.Level.current ctxt in
-  let pkh_from_tenderbake_slot slot =
-    Alpha_context.Stake_distribution.slot_owner ctxt level slot
-    >|=? fun (ctxt, consensus_pk1) -> (ctxt, consensus_pk1.delegate)
-  in
-  let* committee =
-    Alpha_context.Dal.Attestation.compute_committee
-      ctxt
-      pkh_from_tenderbake_slot
-  in
+  let* committee = Dal_apply.compute_committee ctxt level in
   match
     Environment.Signature.Public_key_hash.Map.find
       delegate
-- 
GitLab


From dddc532ff327dfc952cdfb53aa2218ef1235fc84 Mon Sep 17 00:00:00 2001
From: Eugen Zalinescu <eugen.zalinescu@nomadic-labs.com>
Date: Mon, 5 Dec 2022 11:45:38 +0100
Subject: [PATCH 06/10] Proto/Dal: introduce blocks_per_epoch

---
 .../lib_parameters/default_parameters.ml           |  3 +++
 src/proto_alpha/lib_protocol/alpha_context.mli     |  1 +
 .../lib_protocol/constants_parametric_repr.ml      | 14 ++++++++++----
 .../lib_protocol/constants_parametric_repr.mli     |  1 +
 src/proto_alpha/lib_protocol/constants_repr.ml     | 10 ++++++++++
 src/proto_alpha/lib_protocol/raw_context.ml        |  1 +
 6 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/src/proto_alpha/lib_parameters/default_parameters.ml b/src/proto_alpha/lib_parameters/default_parameters.ml
index e6a7a7e83825..5a205a41c382 100644
--- a/src/proto_alpha/lib_parameters/default_parameters.ml
+++ b/src/proto_alpha/lib_parameters/default_parameters.ml
@@ -73,6 +73,7 @@ let default_dal =
       number_of_slots = 256;
       attestation_lag = 1;
       availability_threshold = 50;
+      blocks_per_epoch = 32l;
       cryptobox_parameters = default_cryptobox_parameters;
     }
 
@@ -289,6 +290,7 @@ let constants_sandbox =
         {
           constants_mainnet.dal with
           number_of_slots = 16;
+          blocks_per_epoch = 2l;
           cryptobox_parameters =
             derive_cryptobox_parameters
               ~redundancy_factor:8
@@ -335,6 +337,7 @@ let constants_test =
         {
           constants_mainnet.dal with
           number_of_slots = 8;
+          blocks_per_epoch = 2l;
           cryptobox_parameters =
             derive_cryptobox_parameters
               ~redundancy_factor:4
diff --git a/src/proto_alpha/lib_protocol/alpha_context.mli b/src/proto_alpha/lib_protocol/alpha_context.mli
index 0f5a2ee5c2d7..62aaf873b52b 100644
--- a/src/proto_alpha/lib_protocol/alpha_context.mli
+++ b/src/proto_alpha/lib_protocol/alpha_context.mli
@@ -794,6 +794,7 @@ module Constants : sig
       number_of_slots : int;
       attestation_lag : int;
       availability_threshold : int;
+      blocks_per_epoch : int32;
       cryptobox_parameters : Dal.parameters;
     }
 
diff --git a/src/proto_alpha/lib_protocol/constants_parametric_repr.ml b/src/proto_alpha/lib_protocol/constants_parametric_repr.ml
index a95a8e78c031..358b0efbb35c 100644
--- a/src/proto_alpha/lib_protocol/constants_parametric_repr.ml
+++ b/src/proto_alpha/lib_protocol/constants_parametric_repr.ml
@@ -30,6 +30,7 @@ type dal = {
   number_of_slots : int;
   attestation_lag : int;
   availability_threshold : int;
+  blocks_per_epoch : int32;
   cryptobox_parameters : Dal.parameters;
 }
 
@@ -42,30 +43,35 @@ let dal_encoding =
            attestation_lag;
            availability_threshold;
            cryptobox_parameters;
+           blocks_per_epoch;
          } ->
       ( ( feature_enable,
           number_of_slots,
           attestation_lag,
-          availability_threshold ),
+          availability_threshold,
+          blocks_per_epoch ),
         cryptobox_parameters ))
     (fun ( ( feature_enable,
              number_of_slots,
              attestation_lag,
-             availability_threshold ),
+             availability_threshold,
+             blocks_per_epoch ),
            cryptobox_parameters ) ->
       {
         feature_enable;
         number_of_slots;
         attestation_lag;
         availability_threshold;
+        blocks_per_epoch;
         cryptobox_parameters;
       })
     (merge_objs
-       (obj4
+       (obj5
           (req "feature_enable" bool)
           (req "number_of_slots" int16)
           (req "attestation_lag" int16)
-          (req "availability_threshold" int16))
+          (req "availability_threshold" int16)
+          (req "blocks_per_epoch" int32))
        Dal.parameters_encoding)
 
 (* The encoded representation of this type is stored in the context as
diff --git a/src/proto_alpha/lib_protocol/constants_parametric_repr.mli b/src/proto_alpha/lib_protocol/constants_parametric_repr.mli
index 0ce06811885f..3033307a1ccd 100644
--- a/src/proto_alpha/lib_protocol/constants_parametric_repr.mli
+++ b/src/proto_alpha/lib_protocol/constants_parametric_repr.mli
@@ -30,6 +30,7 @@ type dal = {
   number_of_slots : int;
   attestation_lag : int;
   availability_threshold : int;
+  blocks_per_epoch : int32;
   cryptobox_parameters : Dal.parameters;
 }
 
diff --git a/src/proto_alpha/lib_protocol/constants_repr.ml b/src/proto_alpha/lib_protocol/constants_repr.ml
index 32d83c860752..ed78dff9ab00 100644
--- a/src/proto_alpha/lib_protocol/constants_repr.ml
+++ b/src/proto_alpha/lib_protocol/constants_repr.ml
@@ -326,6 +326,16 @@ let check_constants constants =
     (Invalid_protocol_constants
        "The number of data availability slot must be between 1 and 256")
   >>? fun () ->
+  error_unless
+    Compare.Int32.(
+      constants.dal.blocks_per_epoch > 0l
+      && constants.dal.blocks_per_epoch <= constants.blocks_per_cycle
+      && Int32.rem constants.blocks_per_cycle constants.dal.blocks_per_epoch
+         = 0l)
+    (Invalid_protocol_constants
+       "The epoch length must be between 1 and blocks_per_cycle, and \
+        blocks_per_epoch must divide blocks_per_cycle.")
+  >>? fun () ->
   error_unless
     Compare.Int.(
       constants.sc_rollup.max_number_of_stored_cemented_commitments > 0)
diff --git a/src/proto_alpha/lib_protocol/raw_context.ml b/src/proto_alpha/lib_protocol/raw_context.ml
index 6bc603a251ae..b1feb28eeb80 100644
--- a/src/proto_alpha/lib_protocol/raw_context.ml
+++ b/src/proto_alpha/lib_protocol/raw_context.ml
@@ -1016,6 +1016,7 @@ let prepare_first_block ~level ~timestamp ctxt =
             number_of_slots = c.dal.number_of_slots;
             attestation_lag = c.dal.endorsement_lag;
             availability_threshold = c.dal.availability_threshold;
+            blocks_per_epoch = 32l;
             cryptobox_parameters;
           }
       in
-- 
GitLab


From 7690f2ebbf361516d1e5db62e81b522925a7de5c Mon Sep 17 00:00:00 2001
From: Eugen Zalinescu <eugen.zalinescu@nomadic-labs.com>
Date: Mon, 5 Dec 2022 13:41:50 +0100
Subject: [PATCH 07/10] Proto/Dal: have one DAL committee per epoch

---
 src/proto_alpha/lib_protocol/dal_apply.ml | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/proto_alpha/lib_protocol/dal_apply.ml b/src/proto_alpha/lib_protocol/dal_apply.ml
index b4e265918217..7942e74f788b 100644
--- a/src/proto_alpha/lib_protocol/dal_apply.ml
+++ b/src/proto_alpha/lib_protocol/dal_apply.ml
@@ -154,8 +154,22 @@ let finalisation ctxt =
 
 let compute_committee ctxt level =
   assert_dal_feature_enabled ctxt >>?= fun () ->
+  let blocks_per_epoch = (Constants.parametric ctxt).dal.blocks_per_epoch in
+  let first_level_in_epoch =
+    match
+      Level.sub
+        ctxt
+        level
+        (Int32.to_int @@ Int32.rem level.Level.cycle_position blocks_per_epoch)
+    with
+    | Some v -> v
+    | None ->
+        (* unreachable, because level.level >= level.cycle_position >=
+           (level.cycle_position mod blocks_per_epoch) *)
+        assert false
+  in
   let pkh_from_tenderbake_slot slot =
-    Stake_distribution.slot_owner ctxt level slot
+    Stake_distribution.slot_owner ctxt first_level_in_epoch slot
     >|=? fun (ctxt, consensus_pk1) -> (ctxt, consensus_pk1.delegate)
   in
   (* This committee is cached because it is the one we will use
-- 
GitLab


From 669aff9262611ad445b7981e9f99f699460d1d13 Mon Sep 17 00:00:00 2001
From: Eugen Zalinescu <eugen.zalinescu@nomadic-labs.com>
Date: Tue, 6 Dec 2022 12:42:27 +0100
Subject: [PATCH 08/10] Tezt/Dal: check that there's one committee per epoch

---
 tezt/lib_tezos/rollup.ml  | 27 +++++++++++++++++++++++
 tezt/lib_tezos/rollup.mli |  8 +++++++
 tezt/tests/dal.ml         | 46 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 81 insertions(+)

diff --git a/tezt/lib_tezos/rollup.ml b/tezt/lib_tezos/rollup.ml
index d55761d62122..53ca0f88c854 100644
--- a/tezt/lib_tezos/rollup.ml
+++ b/tezt/lib_tezos/rollup.ml
@@ -533,6 +533,33 @@ module Dal = struct
         }
   end
 
+  module Committee = struct
+    type member = {attestor : string; first_shard_index : int; power : int}
+
+    type t = member list
+
+    let typ =
+      let open Check in
+      list
+      @@ convert
+           (fun {attestor; first_shard_index; power} ->
+             (attestor, first_shard_index, power))
+           (tuple3 string int int)
+
+    let at_level node ~level =
+      let* json =
+        RPC.(call node @@ get_chain_block_context_dal_shards ~level ())
+      in
+      return
+      @@ List.map
+           (fun json ->
+             let pkh = JSON.(json |=> 0 |> as_string) in
+             let first_shard_index = JSON.(json |=> 1 |=> 0 |> as_int) in
+             let power = JSON.(json |=> 1 |=> 1 |> as_int) in
+             {attestor = pkh; first_shard_index; power})
+           (JSON.as_list json)
+  end
+
   let pad n message =
     let padding = String.make n '\000' in
     message ^ padding
diff --git a/tezt/lib_tezos/rollup.mli b/tezt/lib_tezos/rollup.mli
index eb79d21ba397..80000138ef51 100644
--- a/tezt/lib_tezos/rollup.mli
+++ b/tezt/lib_tezos/rollup.mli
@@ -328,4 +328,12 @@ module Dal : sig
 
     val to_string : Cryptobox.commitment -> string
   end
+
+  module Committee : sig
+    type t
+
+    val typ : t Check.typ
+
+    val at_level : Node.t -> level:int -> t Lwt.t
+  end
 end
diff --git a/tezt/tests/dal.ml b/tezt/tests/dal.ml
index 2498c9435a12..98cfe26e78b4 100644
--- a/tezt/tests/dal.ml
+++ b/tezt/tests/dal.ml
@@ -310,6 +310,48 @@ let test_feature_flag _protocol _parameters _cryptobox node client
     Test.fail "Unexpected entry dal in the context when DAL is disabled" ;
   unit
 
+let test_one_committee_per_epoch _protocol _parameters _cryptobox node _client
+    _bootstrap_key =
+  let* blocks_per_epoch =
+    let* json = RPC.(call node @@ get_chain_block_context_constants ()) in
+    return @@ JSON.(json |-> "dal_parametric" |-> "blocks_per_epoch" |> as_int)
+  in
+  let* current_level =
+    RPC.(call node @@ get_chain_block_helper_current_level ())
+  in
+  (* The test assumes we are at a level when an epoch starts. And
+     that is indeed the case. *)
+  assert (current_level.cycle_position = 0) ;
+  let* first_committee =
+    Rollup.Dal.Committee.at_level node ~level:current_level.level
+  in
+  (* We iterate through (the committees at) levels [current_level +
+     offset], with [offset] from 1 to [blocks_per_epoch]. At offset 0
+     we have the [first_committee] (first in the current epoch). The
+     committees at offsets 1 to [blocks_per_epoch - 1] should be the
+     same as the one at offset 0, the one at [blocks_per_epoch] (first
+     in the next epoch) should be different. *)
+  let rec iter offset =
+    if offset > blocks_per_epoch then unit
+    else
+      let level = current_level.level + offset in
+      let* committee = Rollup.Dal.Committee.at_level node ~level in
+      if offset < blocks_per_epoch then (
+        Check.((first_committee = committee) Rollup.Dal.Committee.typ)
+          ~error_msg:
+            "Unexpected different DAL committees at first level: %L, versus \
+             current level: %R" ;
+        unit)
+      else if offset = blocks_per_epoch then (
+        Check.((first_committee = committee) Rollup.Dal.Committee.typ)
+          ~error_msg:
+            "Unexpected equal DAL committees at first levels in subsequent \
+             epochs: %L and %R" ;
+        unit)
+      else iter (offset + 1)
+  in
+  iter 1
+
 let publish_slot ~source ?level ?fee ?error ~index ~commitment ~proof node
     client =
   let level =
@@ -1628,6 +1670,10 @@ let register ~protocols =
     "feature_flag_is_disabled"
     test_feature_flag
     protocols ;
+  scenario_with_layer1_node
+    "one_committee_per_epoch"
+    test_one_committee_per_epoch
+    protocols ;
 
   (* Tests with layer1 and dal nodes *)
   test_dal_node_startup protocols ;
-- 
GitLab


From 6a5cb63d636b5e5d82112df36b86c16211cd6ad2 Mon Sep 17 00:00:00 2001
From: Eugen Zalinescu <eugen.zalinescu@nomadic-labs.com>
Date: Wed, 7 Dec 2022 15:28:27 +0100
Subject: [PATCH 09/10] Tezt/Dal: fetch more DAL parameters

---
 tezt/lib_tezos/rollup.ml  |  6 ++++++
 tezt/lib_tezos/rollup.mli |  2 ++
 tezt/tests/dal.ml         | 30 +++++++++---------------------
 3 files changed, 17 insertions(+), 21 deletions(-)

diff --git a/tezt/lib_tezos/rollup.ml b/tezt/lib_tezos/rollup.ml
index 53ca0f88c854..5cb9d676d76a 100644
--- a/tezt/lib_tezos/rollup.ml
+++ b/tezt/lib_tezos/rollup.ml
@@ -503,9 +503,11 @@ module Dal = struct
 
   module Parameters = struct
     type t = {
+      feature_enabled : bool;
       cryptobox : Cryptobox.parameters;
       number_of_slots : int;
       attestation_lag : int;
+      blocks_per_epoch : int;
     }
 
     let parameter_file protocol =
@@ -523,13 +525,17 @@ module Dal = struct
       let page_size = JSON.(json |-> "page_size" |> as_int) in
       let number_of_slots = JSON.(json |-> "number_of_slots" |> as_int) in
       let attestation_lag = JSON.(json |-> "attestation_lag" |> as_int) in
+      let blocks_per_epoch = JSON.(json |-> "blocks_per_epoch" |> as_int) in
+      let feature_enabled = JSON.(json |-> "feature_enable" |> as_bool) in
       return
         {
+          feature_enabled;
           cryptobox =
             Cryptobox.Verifier.
               {number_of_shards; redundancy_factor; slot_size; page_size};
           number_of_slots;
           attestation_lag;
+          blocks_per_epoch;
         }
   end
 
diff --git a/tezt/lib_tezos/rollup.mli b/tezt/lib_tezos/rollup.mli
index 80000138ef51..32956bab670c 100644
--- a/tezt/lib_tezos/rollup.mli
+++ b/tezt/lib_tezos/rollup.mli
@@ -219,9 +219,11 @@ module Dal : sig
 
   module Parameters : sig
     type t = {
+      feature_enabled : bool;
       cryptobox : Cryptobox.parameters;
       number_of_slots : int;
       attestation_lag : int;
+      blocks_per_epoch : int;
     }
 
     val parameter_file : Protocol.t -> string Lwt.t
diff --git a/tezt/tests/dal.ml b/tezt/tests/dal.ml
index 98cfe26e78b4..482aa1c2c3de 100644
--- a/tezt/tests/dal.ml
+++ b/tezt/tests/dal.ml
@@ -250,25 +250,13 @@ let test_feature_flag _protocol _parameters _cryptobox node client
      - 2. It checks the new operations added by the feature flag
      cannot be propagated by checking their classification in the
      mempool. *)
-  let* protocol_parameters =
-    RPC.Client.call client @@ RPC.get_chain_block_context_constants ()
-  in
-  let feature_flag =
-    JSON.(
-      protocol_parameters |-> "dal_parametric" |-> "feature_enable" |> as_bool)
-  in
-  let number_of_slots =
-    JSON.(
-      protocol_parameters |-> "dal_parametric" |-> "number_of_slots" |> as_int)
-  in
-  let* parameters = Rollup.Dal.Parameters.from_client client in
-  let cryptobox_params = parameters.cryptobox in
-  let cryptobox = Rollup.Dal.make cryptobox_params in
+  let* params = Rollup.Dal.Parameters.from_client client in
+  let cryptobox = Rollup.Dal.make params.cryptobox in
   let commitment, proof =
     Rollup.Dal.Commitment.dummy_commitment cryptobox "coucou"
   in
   Check.(
-    (feature_flag = false)
+    (params.feature_enabled = false)
       bool
       ~error_msg:"Feature flag for the DAL should be disabled") ;
   let*? process =
@@ -285,7 +273,9 @@ let test_feature_flag _protocol _parameters _cryptobox node client
       inject
         ~force:true
         ~signer:Constant.bootstrap1
-        (dal_attestation ~level ~attestation:(Array.make number_of_slots false))
+        (dal_attestation
+           ~level
+           ~attestation:(Array.make params.number_of_slots false))
         client)
   in
   let* (`OpHash oph2) =
@@ -310,12 +300,10 @@ let test_feature_flag _protocol _parameters _cryptobox node client
     Test.fail "Unexpected entry dal in the context when DAL is disabled" ;
   unit
 
-let test_one_committee_per_epoch _protocol _parameters _cryptobox node _client
+let test_one_committee_per_epoch _protocol _parameters _cryptobox node client
     _bootstrap_key =
-  let* blocks_per_epoch =
-    let* json = RPC.(call node @@ get_chain_block_context_constants ()) in
-    return @@ JSON.(json |-> "dal_parametric" |-> "blocks_per_epoch" |> as_int)
-  in
+  let* params = Rollup.Dal.Parameters.from_client client in
+  let blocks_per_epoch = params.blocks_per_epoch in
   let* current_level =
     RPC.(call node @@ get_chain_block_helper_current_level ())
   in
-- 
GitLab


From 0f71c0a6ab6fd0252df398597dcc2a9eebf5aaa1 Mon Sep 17 00:00:00 2001
From: Eugen Zalinescu <eugen.zalinescu@nomadic-labs.com>
Date: Mon, 12 Dec 2022 09:28:10 +0100
Subject: [PATCH 10/10] Tezt: update regression outputs

---
 ...- (mode client) RPC regression tests- misc_protocol.out | 7 ++++---
 ...a- (mode light) RPC regression tests- misc_protocol.out | 7 ++++---
 ...a- (mode proxy) RPC regression tests- misc_protocol.out | 7 ++++---
 ...erver_data_dir) RPC regression tests- misc_protocol.out | 7 ++++---
 ...oxy_server_rpc) RPC regression tests- misc_protocol.out | 7 ++++---
 5 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/tezt/tests/expected/RPC_test.ml/Alpha- (mode client) RPC regression tests- misc_protocol.out b/tezt/tests/expected/RPC_test.ml/Alpha- (mode client) RPC regression tests- misc_protocol.out
index 9791c9158c85..7adb8d7f2532 100644
--- a/tezt/tests/expected/RPC_test.ml/Alpha- (mode client) RPC regression tests- misc_protocol.out	
+++ b/tezt/tests/expected/RPC_test.ml/Alpha- (mode client) RPC regression tests- misc_protocol.out	
@@ -46,9 +46,10 @@
   "tx_rollup_sunset_level": 3473409,
   "dal_parametric":
     { "feature_enable": false, "number_of_slots": 16, "attestation_lag": 1,
-      "availability_threshold": 50, "redundancy_factor": 8, "page_size": 128,
-      "slot_size": 32768, "number_of_shards": 64 },
-  "sc_rollup_enable": false, "sc_rollup_origination_size": 6314,
+      "availability_threshold": 50, "blocks_per_epoch": 2,
+      "redundancy_factor": 8, "page_size": 128, "slot_size": 32768,
+      "number_of_shards": 64 }, "sc_rollup_enable": false,
+  "sc_rollup_origination_size": 6314,
   "sc_rollup_challenge_window_in_blocks": 20160,
   "sc_rollup_stake_amount": "10000000000",
   "sc_rollup_commitment_period_in_blocks": 30,
diff --git a/tezt/tests/expected/RPC_test.ml/Alpha- (mode light) RPC regression tests- misc_protocol.out b/tezt/tests/expected/RPC_test.ml/Alpha- (mode light) RPC regression tests- misc_protocol.out
index 94771e38790e..798d70c46406 100644
--- a/tezt/tests/expected/RPC_test.ml/Alpha- (mode light) RPC regression tests- misc_protocol.out	
+++ b/tezt/tests/expected/RPC_test.ml/Alpha- (mode light) RPC regression tests- misc_protocol.out	
@@ -46,9 +46,10 @@
   "tx_rollup_sunset_level": 3473409,
   "dal_parametric":
     { "feature_enable": false, "number_of_slots": 16, "attestation_lag": 1,
-      "availability_threshold": 50, "redundancy_factor": 8, "page_size": 128,
-      "slot_size": 32768, "number_of_shards": 64 },
-  "sc_rollup_enable": false, "sc_rollup_origination_size": 6314,
+      "availability_threshold": 50, "blocks_per_epoch": 2,
+      "redundancy_factor": 8, "page_size": 128, "slot_size": 32768,
+      "number_of_shards": 64 }, "sc_rollup_enable": false,
+  "sc_rollup_origination_size": 6314,
   "sc_rollup_challenge_window_in_blocks": 20160,
   "sc_rollup_stake_amount": "10000000000",
   "sc_rollup_commitment_period_in_blocks": 30,
diff --git a/tezt/tests/expected/RPC_test.ml/Alpha- (mode proxy) RPC regression tests- misc_protocol.out b/tezt/tests/expected/RPC_test.ml/Alpha- (mode proxy) RPC regression tests- misc_protocol.out
index 9d57a015a373..e7a4dbb24319 100644
--- a/tezt/tests/expected/RPC_test.ml/Alpha- (mode proxy) RPC regression tests- misc_protocol.out	
+++ b/tezt/tests/expected/RPC_test.ml/Alpha- (mode proxy) RPC regression tests- misc_protocol.out	
@@ -46,9 +46,10 @@
   "tx_rollup_sunset_level": 3473409,
   "dal_parametric":
     { "feature_enable": false, "number_of_slots": 16, "attestation_lag": 1,
-      "availability_threshold": 50, "redundancy_factor": 8, "page_size": 128,
-      "slot_size": 32768, "number_of_shards": 64 },
-  "sc_rollup_enable": false, "sc_rollup_origination_size": 6314,
+      "availability_threshold": 50, "blocks_per_epoch": 2,
+      "redundancy_factor": 8, "page_size": 128, "slot_size": 32768,
+      "number_of_shards": 64 }, "sc_rollup_enable": false,
+  "sc_rollup_origination_size": 6314,
   "sc_rollup_challenge_window_in_blocks": 20160,
   "sc_rollup_stake_amount": "10000000000",
   "sc_rollup_commitment_period_in_blocks": 30,
diff --git a/tezt/tests/expected/RPC_test.ml/Alpha- (mode proxy_server_data_dir) RPC regression tests- misc_protocol.out b/tezt/tests/expected/RPC_test.ml/Alpha- (mode proxy_server_data_dir) RPC regression tests- misc_protocol.out
index 1b08b3512c50..07e0eb63f9bc 100644
--- a/tezt/tests/expected/RPC_test.ml/Alpha- (mode proxy_server_data_dir) RPC regression tests- misc_protocol.out	
+++ b/tezt/tests/expected/RPC_test.ml/Alpha- (mode proxy_server_data_dir) RPC regression tests- misc_protocol.out	
@@ -46,9 +46,10 @@
   "tx_rollup_sunset_level": 3473409,
   "dal_parametric":
     { "feature_enable": false, "number_of_slots": 16, "attestation_lag": 1,
-      "availability_threshold": 50, "redundancy_factor": 8, "page_size": 128,
-      "slot_size": 32768, "number_of_shards": 64 },
-  "sc_rollup_enable": false, "sc_rollup_origination_size": 6314,
+      "availability_threshold": 50, "blocks_per_epoch": 2,
+      "redundancy_factor": 8, "page_size": 128, "slot_size": 32768,
+      "number_of_shards": 64 }, "sc_rollup_enable": false,
+  "sc_rollup_origination_size": 6314,
   "sc_rollup_challenge_window_in_blocks": 20160,
   "sc_rollup_stake_amount": "10000000000",
   "sc_rollup_commitment_period_in_blocks": 30,
diff --git a/tezt/tests/expected/RPC_test.ml/Alpha- (mode proxy_server_rpc) RPC regression tests- misc_protocol.out b/tezt/tests/expected/RPC_test.ml/Alpha- (mode proxy_server_rpc) RPC regression tests- misc_protocol.out
index 1b08b3512c50..07e0eb63f9bc 100644
--- a/tezt/tests/expected/RPC_test.ml/Alpha- (mode proxy_server_rpc) RPC regression tests- misc_protocol.out	
+++ b/tezt/tests/expected/RPC_test.ml/Alpha- (mode proxy_server_rpc) RPC regression tests- misc_protocol.out	
@@ -46,9 +46,10 @@
   "tx_rollup_sunset_level": 3473409,
   "dal_parametric":
     { "feature_enable": false, "number_of_slots": 16, "attestation_lag": 1,
-      "availability_threshold": 50, "redundancy_factor": 8, "page_size": 128,
-      "slot_size": 32768, "number_of_shards": 64 },
-  "sc_rollup_enable": false, "sc_rollup_origination_size": 6314,
+      "availability_threshold": 50, "blocks_per_epoch": 2,
+      "redundancy_factor": 8, "page_size": 128, "slot_size": 32768,
+      "number_of_shards": 64 }, "sc_rollup_enable": false,
+  "sc_rollup_origination_size": 6314,
   "sc_rollup_challenge_window_in_blocks": 20160,
   "sc_rollup_stake_amount": "10000000000",
   "sc_rollup_commitment_period_in_blocks": 30,
-- 
GitLab