Merge pull request #160 from martindevans/GetState_fix

`GetState()` fix

LLama/LLamaContext.cs

@@ -195,32 +195,24 @@ namespace LLama
 
             unsafe
             {
-                var bigMemory = Marshal.AllocHGlobal((nint)stateSize);
-                var smallMemory = IntPtr.Zero;
+                // Allocate a chunk of memory large enough to hold the entire state
+                var memory = Marshal.AllocHGlobal((nint)stateSize);
                 try
                 {
-                    // Copy the state data into "big memory", discover the actual size required
-                    var actualSize = _ctx.GetState(bigMemory, stateSize);
+                    // Copy the state data into memory, discover the actual size required
+                    var actualSize = _ctx.GetState(memory, stateSize);
 
-                    // if big memory is nearly completely full (within 1MB) early exit and skip the extra copying
-                    if (actualSize >= stateSize - 1_000_000)
-                        return new State(bigMemory);
+                    // Shrink to size
+                    memory = Marshal.ReAllocHGlobal(memory, (nint)actualSize);
 
-                    // Allocate a smaller buffer which is exactly the right size
-                    smallMemory = Marshal.AllocHGlobal((nint)actualSize);
-
-                    // Copy into the smaller buffer and free the large one to save excess memory usage
-                    Buffer.MemoryCopy(bigMemory.ToPointer(), smallMemory.ToPointer(), actualSize, actualSize);
-
-                    return new State(smallMemory);
+                    // Wrap memory in a state and return it
+                    memory = IntPtr.Zero;
+                    return new State(memory);
                 }
-                catch
+                finally
                 {
-                    if (bigMemory != IntPtr.Zero)
-                        Marshal.FreeHGlobal(bigMemory);
-                    if (smallMemory != IntPtr.Zero)
-                        Marshal.FreeHGlobal(smallMemory);
-                    throw;
+                    if (memory != IntPtr.Zero)
+                        Marshal.FreeHGlobal(memory);
                 }
             }
         }