Allow external cache when deriving miniscripts

Author: NicolasDorier

NBitcoin/NBitcoin.csproj

@@ -12,7 +12,7 @@
 		<RepositoryType>git</RepositoryType>
 	</PropertyGroup>
 	<PropertyGroup>
-		<Version Condition=" '$(Version)' == '' ">8.0.13</Version>
+		<Version Condition=" '$(Version)' == '' ">8.0.14</Version>
 		<LangVersion>12.0</LangVersion>
 	</PropertyGroup>
 	<PropertyGroup Condition=" '$(Configuration)' == 'Release' ">

NBitcoin/WalletPolicies/DeriveParameters.cs

@@ -1,6 +1,7 @@
 #if !NO_RECORDS
 #nullable enable
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
@@ -9,6 +10,9 @@
 
 namespace NBitcoin.WalletPolicies
 {
+	public class DerivationCache : ConcurrentDictionary<(IHDKey, int), Lazy<IHDKey>>
+	{
+	}
 	public class DeriveParameters
 	{
 		/// <summary>
@@ -54,6 +58,7 @@ public DeriveParameters(AddressIntent intent, int startIndex, int count)
 		}
 		public AddressIntent Intent { get; }
 		public int[] AddressIndexes { get; set; }
+		public DerivationCache? DervivationCache { get; set; }
 	}
 }
 #endif

NBitcoin/WalletPolicies/Miniscript.cs

@@ -819,7 +819,7 @@ public DerivationResult Derive(AddressIntent intent, int index)
 		/// <exception cref="InvalidOperationException"></exception>
 		public DerivationResult[] Derive(DeriveParameters parameters)
 		{
-			var visitor = new DeriveVisitor(parameters.Intent, parameters.AddressIndexes, KeyType);
+			var visitor = new DeriveVisitor(parameters.Intent, parameters.AddressIndexes, parameters.DervivationCache ?? new(), KeyType);
 			return visitor.Derive(RootNode, Network);
 		}
 

NBitcoin/WalletPolicies/Visitors/DeriveVisitor.cs

@@ -11,7 +11,7 @@
 
 namespace NBitcoin.WalletPolicies.Visitors;
 
-internal class DeriveVisitor(AddressIntent Intent, int[] Indexes, KeyType KeyType) : MiniscriptRewriterVisitor
+internal class DeriveVisitor(AddressIntent Intent, int[] Indexes, DerivationCache DerivationCache, KeyType KeyType) : MiniscriptRewriterVisitor
 {
 	Dictionary<MiniscriptNode.MultipathNode, BitcoinExtPubKey[]> _Replacements = new();
 	int idx = -1;
@@ -21,10 +21,9 @@ public DerivationResult[] Derive(MiniscriptNode node, Network network)
 		DerivationResult[] result = new DerivationResult[Indexes.Length];
 		Parallel.For(0, Indexes.Length, i =>
 		{
-			var visitor = new DeriveVisitor(Intent, Indexes, KeyType)
+			var visitor = new DeriveVisitor(Intent, Indexes, DerivationCache, KeyType)
 			{
-				idx = Indexes[i],
-				_DerivedCache = _DerivedCache,
+				idx = Indexes[i]
 			};
 			var miniscript = new Miniscript(visitor.Visit(node), network, KeyType);
 			result[i] = new DerivationResult(miniscript, visitor._Derivations);
@@ -83,14 +82,13 @@ private Derivation GetPublicKey(MiniscriptNode.MultipathNode mki, IHDKey k)
 		});
 	}
 	Dictionary<HDKeyNode, Derivation> _Derivations = new();
-	ConcurrentDictionary<(IHDKey, int), Lazy<IHDKey>> _DerivedCache = new();
 
 	public bool _nestedMusig = false;
 
 	private IHDKey DeriveIntent(IHDKey k, int typeIndex)
 	{
 		// When we derive 0/1/*, "0/1" is common to multiple derivations, so we cache it
-		return _DerivedCache.GetOrAdd((k, typeIndex), new Lazy<IHDKey>(() => k.Derive((uint)typeIndex))).Value;
+		return DerivationCache.GetOrAdd((k, typeIndex), new Lazy<IHDKey>(() => k.Derive((uint)typeIndex))).Value;
 	}
 }
 #endif