From ee810f57dd0aa841742cde74e41dc31915758fa1 Mon Sep 17 00:00:00 2001
From: Bartosz Taudul <wolf.pld@gmail.com>
Date: Sat, 6 Oct 2007 14:41:39 +0200
Subject: [PATCH] - use local mutex, not global - moved mutex handling from FFT
 to FFTW wrapper - use another layer of wrappers around FFTW to be ensure
 thread safety

---
 Plugins/FFT/DCT.cs  |  8 ++++----
 Plugins/FFT/FFT.cs  | 22 ++++++----------------
 Plugins/FFT/FFTW.cs | 51 ++++++++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 56 insertions(+), 25 deletions(-)

diff --git a/Plugins/FFT/DCT.cs b/Plugins/FFT/DCT.cs
index 8e6e936..cc5611c 100644
--- a/Plugins/FFT/DCT.cs
+++ b/Plugins/FFT/DCT.cs
@@ -94,7 +94,7 @@ namespace Eithne
 
 			_out[0] = new ICommImage(res, socket.OriginalImages, socket.Categories);
 
-			FFTW.fftw_cleanup();
+			FFTW.Cleanup();
 
 			_workdone = true;
 		}
@@ -108,12 +108,12 @@ namespace Eithne
 				for(int x=0; x<img.W; x++)
 					datain[x + y*img.W] = (byte)img[x, y];
 
-			IntPtr plan = FFTW.fftw_plan_r2r_2d(img.H, img.W, datain, dataout, FFTW.Kind.FFTW_REDFT10,
+			IntPtr plan = FFTW.PlanR2R2D(img.H, img.W, datain, dataout, FFTW.Kind.FFTW_REDFT10,
 					FFTW.Kind.FFTW_REDFT10, 0);
 
-			FFTW.fftw_execute(plan);
+			FFTW.Execute(plan);
 
-			FFTW.fftw_destroy_plan(plan);
+			FFTW.DestroyPlan(plan);
 
 			IImage ret = new IImage(BPP.Float, img.W, img.H);
 
diff --git a/Plugins/FFT/FFT.cs b/Plugins/FFT/FFT.cs
index 723a52e..7a9919d 100644
--- a/Plugins/FFT/FFT.cs
+++ b/Plugins/FFT/FFT.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Threading;
 using System.Xml;
 using Mono.Unix;
 
@@ -55,7 +54,6 @@ namespace Eithne
 	{
 		private bool zero = true;
 		private float progress = 0;
-		private static Mutex mutex = new Mutex(false, "Eithne.FFT.PreparePlan");
 
 		public FFTPlugin()
 		{
@@ -98,7 +96,7 @@ namespace Eithne
 
 			_out[0] = new ICommImage(res, socket.OriginalImages, socket.Categories);
 
-			FFTW.fftw_cleanup();
+			FFTW.Cleanup();
 
 			_workdone = true;
 		}
@@ -111,13 +109,9 @@ namespace Eithne
 			double[] d1 = new double[w * h * 2];
 			double[] d2 = new double[w * h * 2];
 
-			mutex.WaitOne();
+			IntPtr plan = FFTW.PlanDFT2D(h, w, d1, d2, FFTW.Direction.Forward, 0);
 
-			IntPtr plan = FFTW.fftw_plan_dft_2d(h, w, d1, d2, FFTW.Direction.Forward, 0);
-
-			FFTW.fftw_destroy_plan(plan);
-
-			mutex.ReleaseMutex();
+			FFTW.DestroyPlan(plan);
 		}
 
 		private IImage FFT(IImage img)
@@ -132,15 +126,11 @@ namespace Eithne
 					datain[(x + y*img.W) * 2 + 1] = 0;
 				}
 
-			mutex.WaitOne();
-
-			IntPtr plan = FFTW.fftw_plan_dft_2d(img.H, img.W, datain, dataout, FFTW.Direction.Forward, 0);
-
-			FFTW.fftw_execute(plan);
+			IntPtr plan = FFTW.PlanDFT2D(img.H, img.W, datain, dataout, FFTW.Direction.Forward, 0);
 
-			FFTW.fftw_destroy_plan(plan);
+			FFTW.Execute(plan);
 
-			mutex.ReleaseMutex();
+			FFTW.DestroyPlan(plan);
 
 			IImage ret = new IImage(BPP.Float, img.W, img.H);
 
diff --git a/Plugins/FFT/FFTW.cs b/Plugins/FFT/FFTW.cs
index fdc22a9..0db75ea 100644
--- a/Plugins/FFT/FFTW.cs
+++ b/Plugins/FFT/FFTW.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Runtime.InteropServices;
+using System.Threading;
 
 namespace Eithne
 {
@@ -7,6 +8,8 @@ namespace Eithne
 	{
 		const string dll = "libfftw3-3.dll";
 
+		internal static Mutex mutex = new Mutex();
+
 		internal enum Kind
 		{
 			FFTW_R2HC = 0,		// Fourier
@@ -19,21 +22,59 @@ namespace Eithne
 			Backward = 1
 		}
 
+		internal static void Execute(IntPtr plan)
+		{
+			// fftw_execute is the only thread safe routine in fftw
+			fftw_execute(plan);
+		}
+
+		internal static void DestroyPlan(IntPtr plan)
+		{
+			mutex.WaitOne();
+			fftw_destroy_plan(plan);
+			mutex.ReleaseMutex();
+		}
+
+		internal static void Cleanup()
+		{
+			mutex.WaitOne();
+			fftw_cleanup();
+			mutex.ReleaseMutex();
+		}
+
+		internal static IntPtr PlanR2R2D(int nx, int ny, double[] _in, [Out] double[] _out, Kind kindx, Kind kindy, uint flags)
+		{
+			mutex.WaitOne();
+			IntPtr ret = fftw_plan_r2r_2d(nx, ny, _in, _out, kindx, kindy, flags);
+			mutex.ReleaseMutex();
+
+			return ret;
+		}
+
+		internal static IntPtr PlanDFT2D(int nx, int ny, double[] _in, [Out] double[] _out, Direction sign, uint flags)
+		{
+			mutex.WaitOne();
+			IntPtr ret = fftw_plan_dft_2d(nx, ny, _in, _out, sign, flags);
+			mutex.ReleaseMutex();
+
+			return ret;
+		}
+
 		[DllImport (dll)]
-		internal static extern void fftw_execute(IntPtr plan);
+		private static extern void fftw_execute(IntPtr plan);
 
 		[DllImport (dll)]
-		internal static extern void fftw_destroy_plan(IntPtr plan);
+		private static extern void fftw_destroy_plan(IntPtr plan);
 
 		[DllImport (dll)]
-		internal static extern void fftw_cleanup();
+		private static extern void fftw_cleanup();
 
 		[DllImport (dll)]
-		internal static extern IntPtr fftw_plan_r2r_2d(int nx, int ny, double[] _in, [Out] double[] _out, Kind kindx,
+		private static extern IntPtr fftw_plan_r2r_2d(int nx, int ny, double[] _in, [Out] double[] _out, Kind kindx,
 				Kind kindy, uint flags);
 
 		[DllImport (dll)]
-		internal static extern IntPtr fftw_plan_dft_2d(int nx, int ny, double[] _in, [Out] double[] _out, Direction sign,
+		private static extern IntPtr fftw_plan_dft_2d(int nx, int ny, double[] _in, [Out] double[] _out, Direction sign,
 				uint flags);
 	}
 }
-- 
2.11.4.GIT