Speed up the initialization of ApplicationEngine.

src/neo/SmartContract/ApplicationEngine.Runtime.cs

@@ -157,6 +157,7 @@ internal void SendNotification(UInt160 hash, string eventName, Array state)
         {
             NotifyEventArgs notification = new NotifyEventArgs(ScriptContainer, hash, eventName, (Array)state.DeepCopy());
             Notify?.Invoke(this, notification);
+            notifications ??= new List<NotifyEventArgs>();
             notifications.Add(notification);
         }
 

src/neo/SmartContract/ApplicationEngine.Storage.cs

@@ -1,6 +1,7 @@
 using Neo.Ledger;
 using Neo.SmartContract.Iterators;
 using System;
+using System.Collections.Generic;
 using System.Linq;
 
 namespace Neo.SmartContract
@@ -66,6 +67,7 @@ internal IIterator Find(StorageContext context, byte[] prefix)
         {
             byte[] prefix_key = StorageKey.CreateSearchPrefix(context.Id, prefix);
             StorageIterator iterator = new StorageIterator(Snapshot.Storages.Find(prefix_key).Where(p => p.Key.Key.AsSpan().StartsWith(prefix)).GetEnumerator());
+            disposables ??= new List<IDisposable>();
             disposables.Add(iterator);
             return iterator;
         }

src/neo/SmartContract/ApplicationEngine.cs

@@ -26,13 +26,11 @@ private class InvocationState
         public static event EventHandler<NotifyEventArgs> Notify;
         public static event EventHandler<LogEventArgs> Log;
 
-        public const long GasFree = 0;
-
         private static Dictionary<uint, InteropDescriptor> services;
         private readonly long gas_amount;
         private readonly bool testMode;
-        private readonly List<NotifyEventArgs> notifications = new List<NotifyEventArgs>();
-        private readonly List<IDisposable> disposables = new List<IDisposable>();
+        private List<NotifyEventArgs> notifications;
+        private List<IDisposable> disposables;
         private readonly Dictionary<UInt160, int> invocationCounter = new Dictionary<UInt160, int>();
         private readonly Dictionary<ExecutionContext, InvocationState> invocationStates = new Dictionary<ExecutionContext, InvocationState>();
 
@@ -45,15 +43,21 @@ private class InvocationState
         public UInt160 CurrentScriptHash => CurrentContext?.GetState<ExecutionContextState>().ScriptHash;
         public UInt160 CallingScriptHash => CurrentContext?.GetState<ExecutionContextState>().CallingScriptHash;
         public UInt160 EntryScriptHash => EntryContext?.GetState<ExecutionContextState>().ScriptHash;
-        public IReadOnlyList<NotifyEventArgs> Notifications => notifications;
+        public IReadOnlyList<NotifyEventArgs> Notifications => notifications ?? (IReadOnlyList<NotifyEventArgs>)Array.Empty<NotifyEventArgs>();
 
         public ApplicationEngine(TriggerType trigger, IVerifiable container, StoreView snapshot, long gas, bool testMode = false)
+            : this(trigger, container, snapshot, gas, new ReferenceCounter())
         {
-            this.gas_amount = GasFree + gas;
             this.testMode = testMode;
+        }
+
+        private ApplicationEngine(TriggerType trigger, IVerifiable container, StoreView snapshot, long gas, ReferenceCounter referenceCounter)
+            : base(referenceCounter)
+        {
             this.Trigger = trigger;
             this.ScriptContainer = container;
             this.Snapshot = snapshot;
+            this.gas_amount = gas;
         }
 
         internal void AddGas(long gas)
@@ -196,9 +200,12 @@ internal object Convert(StackItem item, InteropParameterDescriptor descriptor)
 
         public override void Dispose()
         {
-            foreach (IDisposable disposable in disposables)
-                disposable.Dispose();
-            disposables.Clear();
+            if (disposables != null)
+            {
+                foreach (IDisposable disposable in disposables)
+                    disposable.Dispose();
+                disposables = null;
+            }
             base.Dispose();
         }
 
@@ -259,20 +266,20 @@ private static InteropDescriptor Register(string name, string handler, long fixe
         }
 
         public static ApplicationEngine Run(byte[] script, StoreView snapshot,
-            IVerifiable container = null, Block persistingBlock = null, int offset = 0, bool testMode = false, long extraGAS = default)
+            IVerifiable container = null, Block persistingBlock = null, int offset = 0, bool testMode = false, long gas = default)
         {
             snapshot.PersistingBlock = persistingBlock ?? snapshot.PersistingBlock ?? CreateDummyBlock(snapshot);
-            ApplicationEngine engine = new ApplicationEngine(TriggerType.Application, container, snapshot, extraGAS, testMode);
+            ApplicationEngine engine = new ApplicationEngine(TriggerType.Application, container, snapshot, gas, testMode);
             engine.LoadScript(script).InstructionPointer = offset;
             engine.Execute();
             return engine;
         }
 
-        public static ApplicationEngine Run(byte[] script, IVerifiable container = null, Block persistingBlock = null, int offset = 0, bool testMode = false, long extraGAS = default)
+        public static ApplicationEngine Run(byte[] script, IVerifiable container = null, Block persistingBlock = null, int offset = 0, bool testMode = false, long gas = default)
         {
             using (SnapshotView snapshot = Blockchain.Singleton.GetSnapshot())
             {
-                return Run(script, snapshot, container, persistingBlock, offset, testMode, extraGAS);
+                return Run(script, snapshot, container, persistingBlock, offset, testMode, gas);
             }
         }
     }

src/neo/Wallets/AssetDescriptor.cs

@@ -19,7 +19,7 @@ public AssetDescriptor(UInt160 asset_id)
                 sb.EmitAppCall(asset_id, "name");
                 script = sb.ToArray();
             }
-            using ApplicationEngine engine = ApplicationEngine.Run(script, extraGAS: 3_000_000);
+            using ApplicationEngine engine = ApplicationEngine.Run(script, gas: 3_000_000);
             if (engine.State.HasFlag(VMState.FAULT)) throw new ArgumentException();
             this.AssetId = asset_id;
             this.AssetName = engine.ResultStack.Pop().GetString();

src/neo/Wallets/Wallet.cs

@@ -143,7 +143,7 @@ public BigDecimal GetBalance(UInt160 asset_id, params UInt160[] accounts)
                 sb.EmitAppCall(asset_id, "decimals");
                 script = sb.ToArray();
             }
-            using ApplicationEngine engine = ApplicationEngine.Run(script, extraGAS: 20000000L * accounts.Length);
+            using ApplicationEngine engine = ApplicationEngine.Run(script, gas: 20000000L * accounts.Length);
             if (engine.State.HasFlag(VMState.FAULT))
                 return new BigDecimal(0, 0);
             byte decimals = (byte)engine.ResultStack.Pop().GetInteger();
@@ -329,7 +329,7 @@ private Transaction MakeTransaction(StoreView snapshot, byte[] script, Transacti
                 {
                     if (engine.State.HasFlag(VMState.FAULT))
                         throw new InvalidOperationException($"Failed execution for '{script.ToHexString()}'");
-                    tx.SystemFee = Math.Max(engine.GasConsumed - ApplicationEngine.GasFree, 0);
+                    tx.SystemFee = engine.GasConsumed;
                 }
 
                 UInt160[] hashes = tx.GetScriptHashesForVerifying(snapshot);

src/neo/neo.csproj

@@ -27,7 +27,7 @@
     <PackageReference Include="Microsoft.AspNetCore.WebSockets" Version="2.2.1" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="3.1.3" />
     <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="3.1.3" />
-    <PackageReference Include="Neo.VM" Version="3.0.0-CI00230" />
+    <PackageReference Include="Neo.VM" Version="3.0.0-CI00232" />
   </ItemGroup>
 
 </Project>