add Iterator APIs and StorageIterator

1. Add `Neo.Iterator.*`
1. Add `Neo.Storage.Find`

neo/Core/Helper.cs

@@ -70,7 +70,7 @@ internal static bool VerifyScripts(this IVerifiable verifiable)
                 {
                     if (hashes[i] != verifiable.Scripts[i].ScriptHash) return false;
                 }
-                ApplicationEngine engine = new ApplicationEngine(TriggerType.Verification, verifiable, Blockchain.Default, StateReader.Default, Fixed8.Zero);
+                ApplicationEngine engine = new ApplicationEngine(TriggerType.Verification, verifiable, Blockchain.Default, new StateReader(), Fixed8.Zero);
                 engine.LoadScript(verification, false);
                 engine.LoadScript(verifiable.Scripts[i].InvocationScript, true);
                 if (!engine.Execute()) return false;

neo/Implementations/Blockchains/LevelDB/LevelDBBlockchain.cs

@@ -11,6 +11,7 @@
 using System.Linq;
 using System.Reflection;
 using System.Threading;
+using Iterator = Neo.IO.Data.LevelDB.Iterator;
 
 namespace Neo.Implementations.Blockchains.LevelDB
 {

neo/SmartContract/Iterator.cs

@@ -0,0 +1,13 @@
+using Neo.VM;
+using System;
+
+namespace Neo.SmartContract
+{
+    internal abstract class Iterator : IDisposable, IInteropInterface
+    {
+        public abstract void Dispose();
+        public abstract StackItem Key();
+        public abstract bool Next();
+        public abstract StackItem Value();
+    }
+}

neo/SmartContract/StateMachine.cs

@@ -19,9 +19,11 @@ public class StateMachine : StateReader
         private readonly DataCache<StorageKey, StorageItem> storages;
 
         private Dictionary<UInt160, UInt160> contracts_created = new Dictionary<UInt160, UInt160>();
-        private List<NotifyEventArgs> notifications = new List<NotifyEventArgs>();
 
-        public IReadOnlyList<NotifyEventArgs> Notifications => notifications;
+        protected override DataCache<UInt160, AccountState> Accounts => accounts;
+        protected override DataCache<UInt256, AssetState> Assets => assets;
+        protected override DataCache<UInt160, ContractState> Contracts => contracts;
+        protected override DataCache<StorageKey, StorageItem> Storages => storages;
 
         public StateMachine(Block persisting_block, DataCache<UInt160, AccountState> accounts, DataCache<UInt256, AssetState> assets, DataCache<UInt160, ContractState> contracts, DataCache<StorageKey, StorageItem> storages)
         {
@@ -30,7 +32,6 @@ public StateMachine(Block persisting_block, DataCache<UInt160, AccountState> acc
             this.assets = assets.CreateSnapshot();
             this.contracts = contracts.CreateSnapshot();
             this.storages = storages.CreateSnapshot();
-            Notify += StateMachine_Notify;
             Register("Neo.Asset.Create", Asset_Create);
             Register("Neo.Asset.Renew", Asset_Renew);
             Register("Neo.Contract.Create", Contract_Create);
@@ -51,14 +52,6 @@ public StateMachine(Block persisting_block, DataCache<UInt160, AccountState> acc
             #endregion
         }
 
-        private bool CheckStorageContext(StorageContext context)
-        {
-            ContractState contract = contracts.TryGet(context.ScriptHash);
-            if (contract == null) return false;
-            if (!contract.HasStorage) return false;
-            return true;
-        }
-
         public void Commit()
         {
             accounts.Commit();
@@ -67,42 +60,12 @@ public void Commit()
             storages.Commit();
         }
 
-        private void StateMachine_Notify(object sender, NotifyEventArgs e)
-        {
-            notifications.Add(e);
-        }
-
         protected override bool Runtime_GetTime(ExecutionEngine engine)
         {
             engine.EvaluationStack.Push(persisting_block.Timestamp);
             return true;
         }
 
-        protected override bool Blockchain_GetAccount(ExecutionEngine engine)
-        {
-            UInt160 hash = new UInt160(engine.EvaluationStack.Pop().GetByteArray());
-            engine.EvaluationStack.Push(StackItem.FromInterface(accounts[hash]));
-            return true;
-        }
-
-        protected override bool Blockchain_GetAsset(ExecutionEngine engine)
-        {
-            UInt256 hash = new UInt256(engine.EvaluationStack.Pop().GetByteArray());
-            AssetState asset = assets.TryGet(hash);
-            if (asset == null) return false;
-            engine.EvaluationStack.Push(StackItem.FromInterface(asset));
-            return true;
-        }
-
-        protected override bool Blockchain_GetContract(ExecutionEngine engine)
-        {
-            UInt160 hash = new UInt160(engine.EvaluationStack.Pop().GetByteArray());
-            ContractState contract = contracts.TryGet(hash);
-            if (contract == null) return false;
-            engine.EvaluationStack.Push(StackItem.FromInterface(contract));
-            return true;
-        }
-
         private bool Asset_Create(ExecutionEngine engine)
         {
             InvocationTransaction tx = (InvocationTransaction)engine.ScriptContainer;
@@ -295,24 +258,6 @@ private bool Contract_Destroy(ExecutionEngine engine)
             return true;
         }
 
-        protected override bool Storage_Get(ExecutionEngine engine)
-        {
-            if (engine.EvaluationStack.Pop() is InteropInterface _interface)
-            {
-                StorageContext context = _interface.GetInterface<StorageContext>();
-                if (!CheckStorageContext(context)) return false;
-                byte[] key = engine.EvaluationStack.Pop().GetByteArray();
-                StorageItem item = storages.TryGet(new StorageKey
-                {
-                    ScriptHash = context.ScriptHash,
-                    Key = key
-                });
-                engine.EvaluationStack.Push(item?.Value ?? new byte[0]);
-                return true;
-            }
-            return false;
-        }
-
         private bool Storage_Put(ExecutionEngine engine)
         {
             if (engine.EvaluationStack.Pop() is InteropInterface _interface)

neo/SmartContract/StateReader.cs

@@ -1,9 +1,11 @@
 using Neo.Core;
 using Neo.Cryptography.ECC;
 using Neo.IO;
+using Neo.IO.Caching;
 using Neo.VM;
 using Neo.VM.Types;
 using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Numerics;
@@ -13,12 +15,59 @@
 
 namespace Neo.SmartContract
 {
-    public class StateReader : InteropService
+    public class StateReader : InteropService, IDisposable
     {
-        public event EventHandler<NotifyEventArgs> Notify;
-        public event EventHandler<LogEventArgs> Log;
+        public static event EventHandler<NotifyEventArgs> Notify;
+        public static event EventHandler<LogEventArgs> Log;
 
-        public static readonly StateReader Default = new StateReader();
+        private readonly List<NotifyEventArgs> notifications = new List<NotifyEventArgs>();
+        private readonly List<IDisposable> disposables = new List<IDisposable>();
+
+        public IReadOnlyList<NotifyEventArgs> Notifications => notifications;
+
+        private DataCache<UInt160, AccountState> _accounts;
+        protected virtual DataCache<UInt160, AccountState> Accounts
+        {
+            get
+            {
+                if (_accounts == null)
+                    _accounts = Blockchain.Default.GetStates<UInt160, AccountState>();
+                return _accounts;
+            }
+        }
+
+        private DataCache<UInt256, AssetState> _assets;
+        protected virtual DataCache<UInt256, AssetState> Assets
+        {
+            get
+            {
+                if (_assets == null)
+                    _assets = Blockchain.Default.GetStates<UInt256, AssetState>();
+                return _assets;
+            }
+        }
+
+        private DataCache<UInt160, ContractState> _contracts;
+        protected virtual DataCache<UInt160, ContractState> Contracts
+        {
+            get
+            {
+                if (_contracts == null)
+                    _contracts = Blockchain.Default.GetStates<UInt160, ContractState>();
+                return _contracts;
+            }
+        }
+
+        private DataCache<StorageKey, StorageItem> _storages;
+        protected virtual DataCache<StorageKey, StorageItem> Storages
+        {
+            get
+            {
+                if (_storages == null)
+                    _storages = Blockchain.Default.GetStates<StorageKey, StorageItem>();
+                return _storages;
+            }
+        }
 
         public StateReader()
         {
@@ -76,6 +125,10 @@ public StateReader()
             Register("Neo.Contract.GetScript", Contract_GetScript);
             Register("Neo.Storage.GetContext", Storage_GetContext);
             Register("Neo.Storage.Get", Storage_Get);
+            Register("Neo.Storage.Find", Storage_Find);
+            Register("Neo.Iterator.Next", Iterator_Next);
+            Register("Neo.Iterator.Key", Iterator_Key);
+            Register("Neo.Iterator.Value", Iterator_Value);
             #region Old AntShares APIs
             Register("AntShares.Runtime.CheckWitness", Runtime_CheckWitness);
             Register("AntShares.Runtime.Notify", Runtime_Notify);
@@ -128,6 +181,21 @@ public StateReader()
             #endregion
         }
 
+        internal bool CheckStorageContext(StorageContext context)
+        {
+            ContractState contract = Contracts.TryGet(context.ScriptHash);
+            if (contract == null) return false;
+            if (!contract.HasStorage) return false;
+            return true;
+        }
+
+        public void Dispose()
+        {
+            foreach (IDisposable disposable in disposables)
+                disposable.Dispose();
+            disposables.Clear();
+        }
+
         protected virtual bool Runtime_GetTrigger(ExecutionEngine engine)
         {
             ApplicationEngine app_engine = (ApplicationEngine)engine;
@@ -164,7 +232,9 @@ protected virtual bool Runtime_CheckWitness(ExecutionEngine engine)
         protected virtual bool Runtime_Notify(ExecutionEngine engine)
         {
             StackItem state = engine.EvaluationStack.Pop();
-            Notify?.Invoke(this, new NotifyEventArgs(engine.ScriptContainer, new UInt160(engine.CurrentContext.ScriptHash), state));
+            NotifyEventArgs notification = new NotifyEventArgs(engine.ScriptContainer, new UInt160(engine.CurrentContext.ScriptHash), state);
+            Notify?.Invoke(this, notification);
+            notifications.Add(notification);
             return true;
         }
 
@@ -351,8 +421,8 @@ protected virtual bool Blockchain_GetTransaction(ExecutionEngine engine)
 
         protected virtual bool Blockchain_GetAccount(ExecutionEngine engine)
         {
-            byte[] hash = engine.EvaluationStack.Pop().GetByteArray();
-            AccountState account = Blockchain.Default?.GetAccountState(new UInt160(hash));
+            UInt160 hash = new UInt160(engine.EvaluationStack.Pop().GetByteArray());
+            AccountState account = Accounts.GetOrAdd(hash, () => new AccountState(hash));
             engine.EvaluationStack.Push(StackItem.FromInterface(account));
             return true;
         }
@@ -366,16 +436,17 @@ protected virtual bool Blockchain_GetValidators(ExecutionEngine engine)
 
         protected virtual bool Blockchain_GetAsset(ExecutionEngine engine)
         {
-            byte[] hash = engine.EvaluationStack.Pop().GetByteArray();
-            AssetState asset = Blockchain.Default?.GetAssetState(new UInt256(hash));
+            UInt256 hash = new UInt256(engine.EvaluationStack.Pop().GetByteArray());
+            AssetState asset = Assets.TryGet(hash);
+            if (asset == null) return false;
             engine.EvaluationStack.Push(StackItem.FromInterface(asset));
             return true;
         }
 
         protected virtual bool Blockchain_GetContract(ExecutionEngine engine)
         {
             UInt160 hash = new UInt160(engine.EvaluationStack.Pop().GetByteArray());
-            ContractState contract = Blockchain.Default.GetContract(hash);
+            ContractState contract = Contracts.TryGet(hash);
             if (contract == null) return false;
             engine.EvaluationStack.Push(StackItem.FromInterface(contract));
             return true;
@@ -844,11 +915,9 @@ protected virtual bool Storage_Get(ExecutionEngine engine)
             if (engine.EvaluationStack.Pop() is InteropInterface _interface)
             {
                 StorageContext context = _interface.GetInterface<StorageContext>();
-                ContractState contract = Blockchain.Default.GetContract(context.ScriptHash);
-                if (contract == null) return false;
-                if (!contract.HasStorage) return false;
+                if (!CheckStorageContext(context)) return false;
                 byte[] key = engine.EvaluationStack.Pop().GetByteArray();
-                StorageItem item = Blockchain.Default.GetStorageItem(new StorageKey
+                StorageItem item = Storages.TryGet(new StorageKey
                 {
                     ScriptHash = context.ScriptHash,
                     Key = key
@@ -858,5 +927,54 @@ protected virtual bool Storage_Get(ExecutionEngine engine)
             }
             return false;
         }
+
+        protected virtual bool Storage_Find(ExecutionEngine engine)
+        {
+            if (engine.EvaluationStack.Pop() is InteropInterface _interface)
+            {
+                StorageContext context = _interface.GetInterface<StorageContext>();
+                if (!CheckStorageContext(context)) return false;
+                byte[] prefix = engine.EvaluationStack.Pop().GetByteArray();
+                prefix = context.ScriptHash.ToArray().Concat(prefix).ToArray();
+                StorageIterator iterator = new StorageIterator(Storages.Find(prefix).GetEnumerator());
+                engine.EvaluationStack.Push(StackItem.FromInterface(iterator));
+                disposables.Add(iterator);
+                return true;
+            }
+            return false;
+        }
+
+        protected virtual bool Iterator_Next(ExecutionEngine engine)
+        {
+            if (engine.EvaluationStack.Pop() is InteropInterface _interface)
+            {
+                Iterator iterator = _interface.GetInterface<Iterator>();
+                engine.EvaluationStack.Push(iterator.Next());
+                return true;
+            }
+            return false;
+        }
+
+        protected virtual bool Iterator_Key(ExecutionEngine engine)
+        {
+            if (engine.EvaluationStack.Pop() is InteropInterface _interface)
+            {
+                Iterator iterator = _interface.GetInterface<Iterator>();
+                engine.EvaluationStack.Push(iterator.Key());
+                return true;
+            }
+            return false;
+        }
+
+        protected virtual bool Iterator_Value(ExecutionEngine engine)
+        {
+            if (engine.EvaluationStack.Pop() is InteropInterface _interface)
+            {
+                Iterator iterator = _interface.GetInterface<Iterator>();
+                engine.EvaluationStack.Push(iterator.Value());
+                return true;
+            }
+            return false;
+        }
     }
 }

neo/SmartContract/StorageIterator.cs

@@ -0,0 +1,36 @@
+using Neo.Core;
+using Neo.VM;
+using System.Collections.Generic;
+
+namespace Neo.SmartContract
+{
+    internal class StorageIterator : Iterator
+    {
+        private readonly IEnumerator<KeyValuePair<StorageKey, StorageItem>> enumerator;
+
+        public StorageIterator(IEnumerator<KeyValuePair<StorageKey, StorageItem>> enumerator)
+        {
+            this.enumerator = enumerator;
+        }
+
+        public override void Dispose()
+        {
+            enumerator.Dispose();
+        }
+
+        public override StackItem Key()
+        {
+            return enumerator.Current.Key.Key;
+        }
+
+        public override bool Next()
+        {
+            return enumerator.MoveNext();
+        }
+
+        public override StackItem Value()
+        {
+            return enumerator.Current.Value.Value;
+        }
+    }
+}