Merge pull request #9 from z93blom/master

Added support for multithreaded access to chunks

SubstrateCS/Source/Core/RegionFile.cs

@@ -21,6 +21,15 @@ namespace Substrate.Core
 
         private string fileName;
         private FileStream file;
+
+        /// <summary>
+        /// The file lock used so that we do not seek in different areas
+        /// of the same file at the same time. All file access should lock this
+        /// object before moving the file pointer.
+        /// The lock should also surround all access to the sectorFree free variable.
+        /// </summary>
+        private object fileLock = new object();
+
         private int[] offsets;
         private int[] chunkTimestamps;
         private List<Boolean> sectorFree;
@@ -62,10 +71,12 @@ namespace Substrate.Core
 
                 // Cleanup unmanaged resources
                 if (file != null) {
+                    lock (this.fileLock) {
                         file.Close();
                         file = null;
                     }
                 }
+            }
             _disposed = true;
         }
 
@@ -93,6 +104,7 @@ namespace Substrate.Core
             }
 
             try {
+                lock (this.fileLock) {
                     file = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);
 
                     //using (file) {
@@ -161,7 +173,7 @@ namespace Substrate.Core
 
                         chunkTimestamps[i] = lastModValue;
                     }
-                //}
+                }
             }
             catch (IOException e) {
                 System.Console.WriteLine(e.Message);
@@ -234,6 +246,8 @@ namespace Substrate.Core
                 int sectorNumber = offset >> 8;
                 int numSectors = offset & 0xFF;
 
+                lock (this.fileLock)
+                {
                     if (sectorNumber + numSectors > sectorFree.Count) {
                         Debugln("READ", x, z, "invalid sector");
                         return null;
@@ -281,6 +295,7 @@ namespace Substrate.Core
                     Debugln("READ", x, z, "unknown version " + version);
                     return null;
                 }
+            }
             catch (IOException) {
                 Debugln("READ", x, z, "exception");
                 return null;
@@ -368,6 +383,7 @@ namespace Substrate.Core
                 else {
                     /* we need to allocate new sectors */
 
+                    lock (this.fileLock) {
                         /* mark the sectors previously used for this chunk as free */
                         for (int i = 0; i < sectorsAllocated; ++i) {
                             sectorFree[sectorNumber + i] = true;
@@ -420,6 +436,7 @@ namespace Substrate.Core
                             SetOffset(x, z, (sectorNumber << 8) | sectorsNeeded);
                         }
                     }
+                }
                 SetTimestamp(x, z, timestamp);
             }
             catch (IOException e) {
@@ -430,6 +447,7 @@ namespace Substrate.Core
         /* write a chunk data to the region file at specified sector number */
         private void Write (int sectorNumber, byte[] data, int length)
         {
+            lock (this.fileLock) {
                 Debugln(" " + sectorNumber);
                 file.Seek(sectorNumber * SectorBytes, SeekOrigin.Begin);
 
@@ -442,9 +460,11 @@ namespace Substrate.Core
                 file.WriteByte(VERSION_DEFLATE); // chunk version number
                 file.Write(data, 0, length); // chunk data
             }
+        }
 
         public void DeleteChunk (int x, int z)
         {
+            lock (this.fileLock) {
                 int offset = GetOffset(x, z);
                 int sectorNumber = offset >> 8;
                 int sectorsAllocated = offset & 0xFF;
@@ -457,6 +477,7 @@ namespace Substrate.Core
                 SetOffset(x, z, 0);
                 SetTimestamp(x, z, 0);
             }
+        }
 
         /* is this an invalid chunk coordinate? */
         private bool OutOfBounds (int x, int z)
@@ -476,6 +497,7 @@ namespace Substrate.Core
 
         private void SetOffset (int x, int z, int offset)
         {
+            lock (this.fileLock) {
                 offsets[x + z * 32] = offset;
                 file.Seek((x + z * 32) * 4, SeekOrigin.Begin);
 
@@ -487,6 +509,7 @@ namespace Substrate.Core
 
                 file.Write(bytes, 0, 4);
             }
+        }
 
         private int Timestamp ()
         {
@@ -507,6 +530,7 @@ namespace Substrate.Core
 
         public void SetTimestamp (int x, int z, int value)
         {
+            lock (this.fileLock) {
                 chunkTimestamps[x + z * 32] = value;
                 file.Seek(SectorBytes + (x + z * 32) * 4, SeekOrigin.Begin);
 
@@ -518,11 +542,14 @@ namespace Substrate.Core
 
                 file.Write(bytes, 0, 4);
             }
+        }
 
         public void Close ()
         {
+            lock (this.fileLock) {
                 file.Close();
             }
+        }
 
         protected virtual int SectorBytes
         {