Fixed a bug in parallel_for() and added unit tests for it.

dlib/test/CMakeLists.txt

@@ -87,6 +87,7 @@ set (tests
    optimization.cpp
    optimization_test_functions.cpp
    opt_qp_solver.cpp
+   parallel_for.cpp
    parse.cpp
    pipe.cpp
    pixel.cpp

dlib/test/makefile

@@ -102,6 +102,7 @@ SRC += one_vs_one_trainer.cpp
 SRC += optimization.cpp
 SRC += optimization_test_functions.cpp
 SRC += opt_qp_solver.cpp
+SRC += parallel_for.cpp
 SRC += parse.cpp
 SRC += pipe.cpp
 SRC += pixel.cpp

dlib/test/parallel_for.cpp

+// Copyright (C) 2013  Davis E. King (davis@dlib.net)
+// License: Boost Software License   See LICENSE.txt for the full license.
+
+#include "tester.h"
+#include <dlib/threads.h>
+#include <vector>
+#include <sstream>
+
+namespace  
+{
+    using namespace test;
+    using namespace dlib;
+    using namespace std;
+    dlib::logger dlog("test.parallel_for");
+
+    class assign_element
+    {
+    public:
+
+        assign_element(
+            std::vector<int>& vect_
+        ) : vect(vect_){}
+
+        std::vector<int>& vect;
+
+        void go (long i ) 
+        {
+            DLIB_TEST( 0 <= i && i < vect.size());
+            vect[i] = i;
+        }
+
+        void operator() (long i ) const
+        {
+            DLIB_TEST( 0 <= i && i < vect.size());
+            vect[i] = i;
+        }
+
+    };
+
+    void test_parallel_for(long start)
+    {
+        std::vector<int> vect(200,0);
+
+        parallel_for(4, start, vect.size(), assign_element(vect));
+
+        for (unsigned long i = 0; i < start;  ++i)
+        {
+            DLIB_TEST(vect[i] == 0);
+        }
+        for (unsigned long i = start; i < vect.size(); ++i)
+        {
+            DLIB_TEST(vect[i] == i);
+        }
+    }
+
+    void test_parallel_for2(long start)
+    {
+        std::vector<int> vect(200,0);
+
+        assign_element temp(vect);
+        parallel_for(4, start, vect.size(), temp, &assign_element::go);
+
+        for (unsigned long i = 0; i < start;  ++i)
+        {
+            DLIB_TEST(vect[i] == 0);
+        }
+        for (unsigned long i = start; i < vect.size(); ++i)
+        {
+            DLIB_TEST(vect[i] == i);
+        }
+    }
+
+
+    class test_parallel_for_routines : public tester
+    {
+    public:
+        test_parallel_for_routines (
+        ) :
+            tester (
+                "test_parallel_for",       // the command line argument name for this test
+                "Run tests on the parallel_for routines.", // the command line argument description
+                0                     // the number of command line arguments for this test
+            )
+        {
+        }
+
+        void perform_test (
+        )
+        {
+            test_parallel_for(0);
+            test_parallel_for(30);
+            test_parallel_for(50);
+            test_parallel_for2(0);
+            test_parallel_for2(30);
+            test_parallel_for2(50);
+        }
+    };
+
+    test_parallel_for_routines a;
+
+}
+
+
+
+

dlib/threads/parallel_for_extension.h

@@ -100,7 +100,7 @@ namespace dlib
             const long block_size = std::max(1L, num/(num_workers*chunks_per_thread));
             for (long i = 0; i < num; i+=block_size)
             {
-                tp.add_task(obj, funct, i, std::min(i+block_size, num));
+                tp.add_task(obj, funct, begin+i, begin+std::min(i+block_size, num));
             }
             tp.wait_for_all_tasks();
         }