Use iterator for chained header loading

src/Blockcore/Consensus/Chain/ChainRepository.cs

@@ -62,17 +62,17 @@ public Task<ChainedHeader> LoadAsync(ChainedHeader genesisHeader)
 
                     Guard.Assert(data.Hash == genesisHeader.HashBlock); // can't swap networks
 
-                    int index = 0;
-                    while (true)
-                    {
-                        data = this.chainStore.GetChainData((index));
+                    var list = this.chainStore.GetChainData();
 
-                        if (data == null)
-                            break;
+                    foreach (var chainedData in list)
+                    {
+                        // Create a new ChainedHeader with reference to previous. This will build a large object graph of all headers.
+                        tip = new ChainedHeader(chainedData.Hash, chainedData.Work, tip);
 
-                        tip = new ChainedHeader(data.Hash, data.Work, tip);
-                        if (tip.Height == 0) tip.SetChainStore(this.chainStore);
-                        index++;
+                        if (tip.Height == 0)
+                        {
+                            tip.SetChainStore(this.chainStore);
+                        }
                     }
 
                     if (tip == null)

src/Blockcore/Consensus/Chain/ChainStore.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Linq;
 using Blockcore.Consensus.BlockInfo;
 using NBitcoin;
 
@@ -12,6 +13,8 @@ public interface IChainStore
 
         bool PutHeader(BlockHeader blockHeader);
 
+        IEnumerable<ChainData> GetChainData();
+
         ChainData GetChainData(int height);
 
         void PutChainData(IEnumerable<ChainDataItem> items);
@@ -78,6 +81,12 @@ public bool PutHeader(BlockHeader blockHeader)
             return this.headers.TryAdd(blockHeader.GetHash(), blockHeader);
         }
 
+        public IEnumerable<ChainData> GetChainData()
+        {
+            // Order by height and return new array with ChainData.
+            return this.chainData.OrderBy(c => c.Key).Select(c => c.Value);
+        }
+
         public ChainData GetChainData(int height)
         {
             if (!this.chainData.TryGetValue(height, out ChainData data))

src/Features/Persistence/Blockcore.Features.Base.Persistence.LevelDb/LevelDbChainStore.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Blockcore.Configuration;
 using Blockcore.Consensus;
 using Blockcore.Consensus.BlockInfo;
@@ -99,6 +100,34 @@ public bool PutHeader(BlockHeader blockHeader)
             return true;
         }
 
+        public IEnumerable<ChainData> GetChainData()
+        {
+            Dictionary<int, ChainData> list = new Dictionary<int, ChainData>();
+
+            lock (this.locker)
+            {
+                using (var iterator = this.leveldb.CreateIterator())
+                {
+                    iterator.SeekToFirst();
+
+                    while (iterator.IsValid() && iterator.Key()[0] == ChainTableName)
+                    {
+                        var height = BitConverter.ToInt32(iterator.Key().AsSpan(1));
+                        byte[] bytes = iterator.Value();
+
+                        var data = new ChainData();
+                        data.FromBytes(bytes, this.network.Consensus.ConsensusFactory);
+                        list.Add(height, data);
+
+                        iterator.Next();
+                    }
+                }
+            }
+
+            // Order by height and return new array with ChainData.
+            return list.OrderBy(c => c.Key).Select(c => c.Value);
+        }
+
         public ChainData GetChainData(int height)
         {
             byte[] bytes = null;

src/Features/Persistence/Blockcore.Features.Base.Persistence.RocksDb/RocksDbChainStore.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Blockcore.Configuration;
 using Blockcore.Consensus;
 using Blockcore.Consensus.BlockInfo;
@@ -105,6 +106,34 @@ public bool PutHeader(BlockHeader blockHeader)
             return true;
         }
 
+        public IEnumerable<ChainData> GetChainData()
+        {
+            Dictionary<int, ChainData> list = new Dictionary<int, ChainData>();
+
+            lock (this.locker)
+            {
+                using (var iterator = this.rocksdb.NewIterator())
+                {
+                    iterator.SeekToFirst();
+
+                    while (iterator.Valid() && iterator.Key()[0] == ChainTableName)
+                    {
+                        var height = BitConverter.ToInt32(iterator.Key().AsSpan(1));
+                        byte[] bytes = iterator.Value();
+
+                        var data = new ChainData();
+                        data.FromBytes(bytes, this.network.Consensus.ConsensusFactory);
+                        list.Add(height, data);
+
+                        iterator.Next();
+                    }
+                }
+            }
+
+            // Order by height and return new array with ChainData.
+            return list.OrderBy(c => c.Key).Select(c => c.Value);
+        }
+
         public ChainData GetChainData(int height)
         {
             byte[] bytes = null;