Add BloomFilter to levelDB

src/LevelDBStore/IO/Data/LevelDB/Native.cs

@@ -155,6 +155,9 @@ public static class Native
 
         [DllImport("libleveldb", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
         public static extern void leveldb_options_set_filter_policy(IntPtr /*Options*/ options, IntPtr /*FilterPolicy*/ policy);
+
+        [DllImport("libleveldb", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
+        public static extern IntPtr leveldb_filterpolicy_create_bloom(int bits_per_key);
         #endregion
 
         #region ReadOptions

src/LevelDBStore/LevelDBStore/config.json

@@ -1,5 +1,6 @@
-{
+{
   "PluginConfiguration": {
-    "Path": "Data_LevelDB_{0}"
+    "Path": "Data_LevelDB_{0}",
+    "BloomFilterBitsPerKey": 20
   }
 }

src/LevelDBStore/Plugins/Storage/LevelDBStore.cs

@@ -1,21 +1,25 @@
+using Microsoft.Extensions.Configuration;
 using Neo.Persistence;
 
 namespace Neo.Plugins.Storage
 {
     public class LevelDBStore : Plugin, IStoragePlugin
     {
         private string path;
+        private int bloomFilterBitsPerKey;
 
         public override string Description => "Uses LevelDB to store the blockchain data";
 
         protected override void Configure()
         {
-            path = string.Format(GetConfiguration().GetSection("Path").Value ?? "Data_LevelDB_{0}", ProtocolSettings.Default.Magic.ToString("X8"));
+            IConfigurationSection config = GetConfiguration();
+            path = string.Format(config.GetSection("Path").Value ?? "Data_LevelDB_{0}", ProtocolSettings.Default.Magic.ToString("X8"));
+            bloomFilterBitsPerKey = config.GetSection("BloomFilterBitsPerKey")?.Get<int>() ?? 0;
         }
 
         public IStore GetStore()
         {
-            return new Store(path);
+            return new Store(path, bloomFilterBitsPerKey);
         }
     }
 }

src/LevelDBStore/Plugins/Storage/Store.cs

@@ -14,9 +14,12 @@ internal class Store : IStore
         private const byte SYS_Version = 0xf0;
         private readonly DB db;
 
-        public Store(string path)
+        public Store(string path, int bloomFilterBitsPerKey)
         {
-            this.db = DB.Open(path, new Options { CreateIfMissing = true });
+            if (bloomFilterBitsPerKey > 0)
+                this.db = DB.Open(path, new Options { CreateIfMissing = true, FilterPolicy = Native.leveldb_filterpolicy_create_bloom(bloomFilterBitsPerKey) });
+            else
+                this.db = DB.Open(path, new Options { CreateIfMissing = true });
             byte[] value = db.Get(ReadOptions.Default, LHelper.CreateKey(SYS_Version));
             if (value != null && Version.TryParse(Encoding.ASCII.GetString(value), out Version version) && version >= Version.Parse("3.0.0"))
                 return;