From 235849b31cf12bfebfd984700b67ee1a78ba800d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marcin=20W=C3=B3jtowicz?= <marcin.wojtowicz@iohk.io>
Date: Sat, 30 Mar 2024 22:56:03 +0100
Subject: [PATCH] Adds new query for a snapshot of big ledger peers

This change introduces a new query tag and handler
to support retrieval of a snapshot of big ledger peers
from the current tip of a node.
---
 cardano-api/internal/Cardano/Api/Query.hs     | 17 +++++++++++++++++
 .../internal/Cardano/Api/Query/Expr.hs        | 19 +++++++++++++++++--
 cardano-api/src/Cardano/Api.hs                |  1 +
 3 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/cardano-api/internal/Cardano/Api/Query.hs b/cardano-api/internal/Cardano/Api/Query.hs
index cf71e03976..29c66c5768 100644
--- a/cardano-api/internal/Cardano/Api/Query.hs
+++ b/cardano-api/internal/Cardano/Api/Query.hs
@@ -57,6 +57,7 @@ module Cardano.Api.Query
   , LedgerState (..)
   , getProgress
   , getSlotForRelativeTime
+  , decodeBigLedgerPeerSnapshot
 
     -- * Internal conversion functions
   , toLedgerUTxO
@@ -112,6 +113,7 @@ import qualified Ouroboros.Consensus.Shelley.Ledger as Consensus
 import qualified Ouroboros.Consensus.Shelley.Ledger.Query.Types as Consensus
 import           Ouroboros.Network.Block (Serialised (..))
 import           Ouroboros.Network.NodeToClient.Version (NodeToClientVersion (..))
+import           Ouroboros.Network.PeerSelection.LedgerPeers.Type (LedgerPeerSnapshot)
 import           Ouroboros.Network.Protocol.LocalStateQuery.Client (Some (..))
 
 import           Control.Monad.Trans.Except
@@ -296,6 +298,8 @@ data QueryInShelleyBasedEra era result where
   QueryStakeVoteDelegatees
     :: Set StakeCredential
     -> QueryInShelleyBasedEra era (Map StakeCredential (Ledger.DRep StandardCrypto))
+  QueryLedgerPeerSnapshot
+    :: QueryInShelleyBasedEra era (Serialised LedgerPeerSnapshot)
 
 -- | Mapping for queries in Shelley-based eras returning minimal node-to-client protocol versions. More
 -- information about queries versioning can be found:
@@ -314,6 +318,7 @@ instance NodeToClientVersionOf (QueryInShelleyBasedEra era result) where
   nodeToClientVersionOf QueryDebugLedgerState = NodeToClientV_9
   nodeToClientVersionOf QueryProtocolState = NodeToClientV_9
   nodeToClientVersionOf QueryCurrentEpochState = NodeToClientV_9
+  nodeToClientVersionOf QueryLedgerPeerSnapshot = NodeToClientV_9
   -- Babbage >= v13
   nodeToClientVersionOf (QueryPoolState _) = NodeToClientV_14
   nodeToClientVersionOf (QueryPoolDistribution _) = NodeToClientV_14
@@ -468,6 +473,11 @@ decodeStakeSnapshot
   -> Either DecoderError (StakeSnapshot era)
 decodeStakeSnapshot (SerialisedStakeSnapshots (Serialised ls)) = StakeSnapshot <$> Plain.decodeFull ls
 
+decodeBigLedgerPeerSnapshot
+  :: Serialised LedgerPeerSnapshot
+  -> Either DecoderError LedgerPeerSnapshot
+decodeBigLedgerPeerSnapshot = Plain.decodeFull . unSerialised
+
 toShelleyAddrSet
   :: CardanoEra era
   -> Set AddressAny
@@ -703,6 +713,8 @@ toConsensusQueryShelleyBased sbe = \case
    where
     creds' :: Set (Shelley.Credential Shelley.Staking StandardCrypto)
     creds' = Set.map toShelleyStakeCredential creds
+  QueryLedgerPeerSnapshot ->
+    Some (consensusQueryInEraInMode era (Consensus.GetCBOR Consensus.GetBigLedgerPeerSnapshot))
  where
   era = toCardanoEra sbe
 
@@ -984,6 +996,11 @@ fromConsensusQueryResultShelleyBased sbe sbeQuery q' r' =
         Consensus.GetFilteredVoteDelegatees{} ->
           Map.mapKeys fromShelleyStakeCredential r'
         _ -> fromConsensusQueryResultMismatch
+    QueryLedgerPeerSnapshot{} ->
+      case q' of
+        Consensus.GetCBOR Consensus.GetBigLedgerPeerSnapshot ->
+          r'
+        _ -> fromConsensusQueryResultMismatch
 
 -- | This should /only/ happen if we messed up the mapping in 'toConsensusQuery'
 -- and 'fromConsensusQueryResult' so they are inconsistent with each other.
diff --git a/cardano-api/internal/Cardano/Api/Query/Expr.hs b/cardano-api/internal/Cardano/Api/Query/Expr.hs
index 43415793ce..6bba2f318a 100644
--- a/cardano-api/internal/Cardano/Api/Query/Expr.hs
+++ b/cardano-api/internal/Cardano/Api/Query/Expr.hs
@@ -26,6 +26,7 @@ module Cardano.Api.Query.Expr
   , queryStakeSnapshot
   , querySystemStart
   , queryUtxo
+  , queryLedgerPeerSnapshot
   , L.MemberStatus (..)
   , L.CommitteeMembersState (..)
   , queryCommitteeMembersState
@@ -64,6 +65,8 @@ import           Cardano.Ledger.SafeHash
 import qualified Cardano.Ledger.Shelley.LedgerState as L
 import           Cardano.Slotting.Slot
 import           Ouroboros.Consensus.HardFork.Combinator.AcrossEras as Consensus
+import           Ouroboros.Network.Block (Serialised)
+import           Ouroboros.Network.PeerSelection.LedgerPeers (LedgerPeerSnapshot)
 
 import           Data.Map (Map)
 import           Data.Set (Set)
@@ -132,6 +135,19 @@ queryDebugLedgerState
 queryDebugLedgerState sbe =
   queryExpr $ QueryInEra $ QueryInShelleyBasedEra sbe QueryDebugLedgerState
 
+queryLedgerPeerSnapshot
+  :: ()
+  => ShelleyBasedEra era
+  -> LocalStateQueryExpr
+      block
+      point
+      QueryInMode
+      r
+      IO
+      (Either UnsupportedNtcVersionError (Either EraMismatch (Serialised LedgerPeerSnapshot)))
+queryLedgerPeerSnapshot sbe =
+  queryExpr $ QueryInEra $ QueryInShelleyBasedEra sbe QueryLedgerPeerSnapshot
+
 queryEraHistory
   :: ()
   => LocalStateQueryExpr block point QueryInMode r IO (Either UnsupportedNtcVersionError EraHistory)
@@ -303,8 +319,7 @@ queryStakePoolParameters
       (Either UnsupportedNtcVersionError (Either EraMismatch (Map PoolId StakePoolParameters)))
 queryStakePoolParameters sbe poolIds
   | S.null poolIds = pure . pure $ pure mempty
-  | otherwise =
-      queryExpr $ QueryInEra $ QueryInShelleyBasedEra sbe $ QueryStakePoolParameters poolIds
+  | otherwise = queryExpr $ QueryInEra $ QueryInShelleyBasedEra sbe $ QueryStakePoolParameters poolIds
 
 queryStakePools
   :: ()
diff --git a/cardano-api/src/Cardano/Api.hs b/cardano-api/src/Cardano/Api.hs
index 0baabb2da8..01a4b7a6ec 100644
--- a/cardano-api/src/Cardano/Api.hs
+++ b/cardano-api/src/Cardano/Api.hs
@@ -949,6 +949,7 @@ module Cardano.Api
   , queryCurrentEpochState
   , queryCurrentEra
   , queryDebugLedgerState
+  , queryLedgerPeerSnapshot
   , queryEpoch
   , queryConstitutionHash
   , queryEraHistory