Merge pull request #1013 from longfin/feature/cache-blockset

Improve performance of `BlockSet<T>`
planetarium · Sep 23, 2020 · 63048cc · 63048cc
2 parents 072f481 + 7286351
commit 63048cc
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Showing 3 changed files with 48 additions and 5 deletions.
diff --git a/CHANGES.md b/CHANGES.md
@@ -119,6 +119,8 @@ To be released.
  -  `doesTransactionFollowPolicy` parameter became 
     `Func<Transaction<T>, BlockChain<T>, bool>` on `BlockPolicy<T>()`
     constructor.  [[#1012]]
+ -  Added `cacheSize` optional parameter to `BlockSet<T>()` constructor.
+    [[#1013]]
 
 ### Backward-incompatible network protocol changes
 
@@ -257,6 +259,8 @@ To be released.
  -  `BlockChain<T>` instead of `BlockPolicy<T>` became to validate `Block<T>`s to append
     so that even if an empty implementation of `IBlockPolicy<T>` is used `Block<T>`s are
     unable to be appended to `BlockChain<T>`.  [[#1010]]
+ -  `BlockSet<T>[HashDigest<SHA256>]` and `BlockChain<T>.Genesis` became cached
+    so that they become faster to get.  [[#1013]]
 
 ### Bug fixes
 
@@ -359,6 +363,7 @@ To be released.
 [#1004]: https://github.com/planetarium/libplanet/pull/1004
 [#1010]: https://github.com/planetarium/libplanet/pull/1010
 [#1012]: https://github.com/planetarium/libplanet/pull/1012
+[#1013]: https://github.com/planetarium/libplanet/pull/1013
 [sleep mode]: https://en.wikipedia.org/wiki/Sleep_mode
 
 

diff --git a/Libplanet/Blockchain/BlockChain.cs b/Libplanet/Blockchain/BlockChain.cs
@@ -62,6 +62,11 @@ public class BlockChain<T>
         /// </summary>
         private IDictionary<TxId, Transaction<T>> _transactions;
 
+        /// <summary>
+        /// Cached genesis block.
+        /// </summary>
+        private Block<T> _genesis;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="BlockChain{T}"/> class.
         /// </summary>
@@ -235,7 +240,7 @@ public Block<T> Tip
         /// <summary>
         /// The first <see cref="Block{T}"/> in the <see cref="BlockChain{T}"/>.
         /// </summary>
-        public Block<T> Genesis => this[0];
+        public Block<T> Genesis => _genesis ??= this[0];
 
         public Guid Id { get; private set; }
 

diff --git a/Libplanet/Store/BlockSet.cs b/Libplanet/Store/BlockSet.cs
@@ -4,23 +4,27 @@
 using System.Security.Cryptography;
 using Libplanet.Action;
 using Libplanet.Blocks;
+using LruCacheNet;
 
 namespace Libplanet.Store
 {
     public class BlockSet<T> : BaseIndex<HashDigest<SHA256>, Block<T>>
         where T : IAction, new()
     {
-        public BlockSet(IStore store)
+        private readonly LruCache<HashDigest<SHA256>, Block<T>> _cache;
+
+        public BlockSet(IStore store, int cacheSize = 4096)
             : base(store)
         {
+            _cache = new LruCache<HashDigest<SHA256>, Block<T>>(cacheSize);
         }
 
         public override ICollection<HashDigest<SHA256>> Keys =>
             Store.IterateBlockHashes().ToList();
 
         public override ICollection<Block<T>> Values =>
             Store.IterateBlockHashes()
-                .Select(Store.GetBlock<T>)
+                .Select(GetBlock)
                 .ToList();
 
         public override int Count => (int)Store.CountBlocks();
@@ -31,7 +35,7 @@ public override Block<T> this[HashDigest<SHA256> key]
         {
             get
             {
-                Block<T> block = Store.GetBlock<T>(key);
+                Block<T> block = GetBlock(key);
                 if (block is null)
                 {
                     throw new KeyNotFoundException(
@@ -58,6 +62,7 @@ public override Block<T> this[HashDigest<SHA256> key]
 
                 value.Validate(DateTimeOffset.UtcNow);
                 Store.PutBlock(value);
+                _cache.Add(value.Hash, value);
             }
         }
 
@@ -74,7 +79,35 @@ public override bool ContainsKey(HashDigest<SHA256> key)
 
         public override bool Remove(HashDigest<SHA256> key)
         {
-            return Store.DeleteBlock(key);
+            bool deleted = Store.DeleteBlock(key);
+
+            _cache.Remove(key);
+
+            return deleted;
+        }
+
+        private Block<T> GetBlock(HashDigest<SHA256> key)
+        {
+            if (_cache.TryGetValue(key, out Block<T> cached))
+            {
+                if (Store.ContainsBlock(key))
+                {
+                    return cached;
+                }
+                else
+                {
+                    // The cached block had been deleted on Store...
+                    _cache.Remove(key);
+                }
+            }
+
+            Block<T> fetched = Store.GetBlock<T>(key);
+            if (!(fetched is null))
+            {
+                _cache.Add(key, fetched);
+            }
+
+            return fetched;
         }
     }
 }