Start work on compressed BlockDB format, to address #413

MCGalaxy/Database/BlockDB/BlockDBFile.V2.cs

@@ -0,0 +1,130 @@
+/*
+    Copyright 2015 MCGalaxy
+        
+    Dual-licensed under the Educational Community License, Version 2.0 and
+    the GNU General Public License, Version 3 (the "Licenses"); you may
+    not use this file except in compliance with the Licenses. You may
+    obtain a copy of the Licenses at
+    
+    http://www.opensource.org/licenses/ecl2.php
+    http://www.gnu.org/licenses/gpl-3.0.html
+    
+    Unless required by applicable law or agreed to in writing,
+    software distributed under the Licenses are distributed on an "AS IS"
+    BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+    or implied. See the Licenses for the specific language governing
+    permissions and limitations under the Licenses.
+ */
+using System;
+using System.IO;
+using MCGalaxy.Util;
+
+namespace MCGalaxy.DB {
+    
+    public unsafe sealed class BlockDBFile_V2 : BlockDBFile {
+        const int BlockSize = 4096;
+        
+        /* TODO: Last chunk may only be partial. need to prepend these entries when compressing. */
+        public override void WriteEntries(Stream s, FastList<BlockDBEntry> entries) {
+            throw new NotImplementedException();
+        }
+
+        public override void WriteEntries(Stream s, BlockDBCache cache) {
+            throw new NotImplementedException();
+        }
+
+        public override long CountEntries(Stream s) {
+            byte[] data = new byte[8];
+            s.Position = 16;
+            BlockDBFile.ReadFully(s, data, data.Length);
+            
+            uint lo = (uint)ReadInt32(data, 0);
+            uint hi = (uint)ReadInt32(data, 4);
+            return (long)((ulong)lo | ((ulong)hi << 32));
+        }
+        
+        public unsafe override int ReadForward(Stream s, byte[] bulk, BlockDBEntry* entriesPtr) {
+            long remaining = s.Length - s.Position;
+            if (remaining == 0) return 0;
+            int bytes = (int)Math.Min(remaining, BlockSize);
+            
+            /* TODO: BULK POINTS TO ENTRIESPTR, FIX THIS */
+            BlockDBFile.ReadFully(s, bulk, bytes);
+            return DecompressChunk(bulk, entriesPtr);
+        }
+        
+        public unsafe override int ReadBackward(Stream s, byte[] bulk, BlockDBEntry* entriesPtr) {
+            long pos = s.Position;
+            if (pos > BlockSize) {
+                int bytes = (int)Math.Min(pos - BlockSize, BlockSize);
+                pos -= bytes;
+                s.Position = pos;
+                BlockDBFile.ReadFully(s, bulk, bytes);
+                s.Position = pos; // set correct position for next backward read            
+                return DecompressChunk(bulk, entriesPtr);
+            }
+            return 0;
+        }
+        
+        unsafe static int DecompressChunk(byte[] bulk, BlockDBEntry* ptr) {
+            byte comp = bulk[0];
+            int count = bulk[1] | (bulk[2] << 8);
+            int idx = 3;
+            
+            int playerID = 0;
+            if ((comp & 0x01) < 0x01) { playerID = ReadInt32(bulk, idx); idx += 4; }
+            int time = 0;
+            if ((comp & 0x06) < 0x06) { time = ReadInt32(bulk, idx); idx += 4; }
+            int index = 0;
+            if ((comp & 0x18) < 0x18) { index = ReadInt32(bulk, idx); idx += 4; }
+            
+            byte oldRaw = 0;
+            if ((comp & 0x20) < 0x20) { oldRaw = bulk[idx]; idx++; }
+            byte newRaw = 0;
+            if ((comp & 0x40) < 0x40) { newRaw = bulk[idx]; idx++; }
+            ushort flags = 0;
+            if ((comp & 0x80) < 0x80) { flags = (ushort)(bulk[idx] | (bulk[idx + 1] << 8)); idx += 2; }
+
+            for (int i = 0; i < count; i++) {
+                switch (comp & 0x01) {
+                    case 0x00: ptr->PlayerID = playerID; break;
+                    default: ptr->PlayerID = ReadInt32(bulk, idx); idx += 4; break;
+                }
+                
+                switch ((comp & 0x06) >> 1) {
+                    case 0: ptr->TimeDelta = time; break;
+                    case 1: ptr->TimeDelta = time + bulk[idx]; idx++; break;
+                    case 2: ptr->TimeDelta = time + (bulk[idx] | (bulk[idx + 1] << 8)); idx += 2; break;
+                    case 3: ptr->TimeDelta = ReadInt32(bulk, idx); idx += 4; break;
+                }
+                
+                switch ((comp & 0x18) >> 3) {
+                    case 0: ptr->Index = index; break;
+                    case 1: ptr->Index = index + (sbyte)bulk[idx]; idx++; break;
+                    case 2: ptr->Index = index + (short)(bulk[idx] | (bulk[idx + 1] << 8)); idx += 2; break;
+                    case 3: ptr->Index = ReadInt32(bulk, idx); idx += 4; break;
+                }
+                
+                switch (comp & 0x20) {
+                    case 0x00: ptr->OldRaw = oldRaw; break;
+                    default: ptr->OldRaw = bulk[idx]; idx++; break;
+                }
+                
+                switch (comp & 0x40) {
+                    case 0x00: ptr->NewRaw = newRaw; break;
+                    default: ptr->NewRaw = bulk[idx]; idx++; break;
+                }
+                
+                switch (comp & 0x80) {
+                    case 0x00: ptr->Flags = flags; break;
+                    default: ptr->Flags = (ushort)(bulk[idx] | (bulk[idx + 1] << 8)); idx += 2; break;
+                }
+            }
+            return count;
+        }
+        
+        static int ReadInt32(byte[] bulk, int idx) {
+            return bulk[idx] | (bulk[idx + 1] << 8) | (bulk[idx + 2] << 16) | (bulk[idx + 3] << 24);
+        }
+    }
+}

MCGalaxy/MCGalaxy_.csproj

@@ -406,6 +406,7 @@
     <Compile Include="Database\BlockDB\BlockDBEntry.cs" />
     <Compile Include="Database\BlockDB\BlockDBChange.cs" />
     <Compile Include="Database\BlockDB\BlockDBFile.V1.cs" />
+    <Compile Include="Database\BlockDB\BlockDBFile.V2.cs" />
     <Compile Include="Database\BlockDB\DBUpgrader.cs" />
     <Compile Include="Database\BlockDB\BlockDBTableDumper.cs" />
     <Compile Include="Database\BlockDB\NameConverter.cs" />