LibC: Replace Berkley's qsort() with AK::dual_pivot_quick_sort() wrapper

Libraries/LibC/qsort.cpp

@@ -24,103 +24,81 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-/*-
+#include <AK/Assertions.h>
- * Copyright (c) 1980, 1983, 1990 The Regents of the University of California.
+#include <AK/QuickSort.h>
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- *    must display the following acknowledgement:
- *	This product includes software developed by the University of
- *	California, Berkeley and its contributors.
- * 4. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)qsort.c	5.9 (Berkeley) 2/23/91";
-#endif /* LIBC_SCCS and not lint */
-
 #include <stdlib.h>
 #include <sys/types.h>
 
-static void insertion_sort(void* bot, size_t nmemb, size_t size, int (*compar)(const void*, const void*));
+class SizedObject {
-static void insertion_sort_r(void* bot, size_t nmemb, size_t size, int (*compar)(const void*, const void*, void*), void* arg);
+public:
+    SizedObject() = delete;
+    SizedObject(void* data, size_t size)
+        : m_data(data)
+        , m_size(size)
+    {
+    }
+    void* data() const { return m_data; }
+    size_t size() const { return m_size; }
+
+private:
+    void* m_data;
+    size_t m_size;
+};
+
+namespace AK {
+
+template<>
+inline void swap(const SizedObject& a, const SizedObject& b)
+{
+    ASSERT(a.size() == b.size());
+    const size_t size = a.size();
+    const auto a_data = reinterpret_cast<char*>(a.data());
+    const auto b_data = reinterpret_cast<char*>(b.data());
+    for (auto i = 0u; i < size; ++i) {
+        swap(a_data[i], b_data[i]);
+    }
+}
+
+}
+
+class SizedObjectSlice {
+public:
+    SizedObjectSlice() = delete;
+    SizedObjectSlice(void* data, size_t num_elements, size_t element_size)
+        : m_data(data)
+        , m_num_elements(num_elements)
+        , m_element_size(element_size)
+    {
+    }
+    const SizedObject operator[](size_t index)
+    {
+        return { static_cast<char*>(m_data) + index * m_element_size, m_element_size };
+    }
+
+private:
+    void* m_data;
+    size_t m_num_elements;
+    size_t m_element_size;
+};
 
 void qsort(void* bot, size_t nmemb, size_t size, int (*compar)(const void*, const void*))
 {
-    if (nmemb <= 1)
+    if (nmemb <= 1) {
         return;
+    }
 
-    insertion_sort(bot, nmemb, size, compar);
+    SizedObjectSlice slice { bot, nmemb, size };
+
+    AK::dual_pivot_quick_sort(slice, 0, nmemb - 1, [=](const SizedObject& a, const SizedObject& b) { return compar(a.data(), b.data()) < 0; });
 }
 
 void qsort_r(void* bot, size_t nmemb, size_t size, int (*compar)(const void*, const void*, void*), void* arg)
 {
-    if (nmemb <= 1)
+    if (nmemb <= 1) {
         return;
-
-    insertion_sort_r(bot, nmemb, size, compar, arg);
-}
-
-void insertion_sort(void* bot, size_t nmemb, size_t size, int (*compar)(const void*, const void*))
-{
-    int cnt;
-    unsigned char ch;
-    char *s1, *s2, *t1, *t2, *top;
-    top = (char*)bot + nmemb * size;
-    for (t1 = (char*)bot + size; t1 < top;) {
-        for (t2 = t1; (t2 -= size) >= bot && compar(t1, t2) < 0;)
-            ;
-        if (t1 != (t2 += size)) {
-            for (cnt = size; cnt--; ++t1) {
-                ch = *t1;
-                for (s1 = s2 = t1; (s2 -= size) >= t2; s1 = s2)
-                    *s1 = *s2;
-                *s1 = ch;
-            }
-        } else
-            t1 += size;
     }
-}
 
-void insertion_sort_r(void* bot, size_t nmemb, size_t size, int (*compar)(const void*, const void*, void*), void* arg)
+    SizedObjectSlice slice { bot, nmemb, size };
-{
+
-    int cnt;
+    AK::dual_pivot_quick_sort(slice, 0, nmemb - 1, [=](const SizedObject& a, const SizedObject& b) { return compar(a.data(), b.data(), arg) < 0; });
-    unsigned char ch;
-    char *s1, *s2, *t1, *t2, *top;
-    top = (char*)bot + nmemb * size;
-    for (t1 = (char*)bot + size; t1 < top;) {
-        for (t2 = t1; (t2 -= size) >= bot && compar(t1, t2, arg) < 0;)
-            ;
-        if (t1 != (t2 += size)) {
-            for (cnt = size; cnt--; ++t1) {
-                ch = *t1;
-                for (s1 = s2 = t1; (s2 -= size) >= t2; s1 = s2)
-                    *s1 = *s2;
-                *s1 = ch;
-            }
-        } else
-            t1 += size;
-    }
 }

Tests/LibC/qsort-sorts-and-copies.cpp

@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2020, Sahan Fernando <sahan.h.fernando@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/QuickSort.h>
+#include <AK/String.h>
+#include <AK/Vector.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+const size_t NUM_RUNS = 100;
+
+struct SortableObject {
+    int m_key;
+    int m_payload;
+};
+
+int compare_sortable_object(const void* a, const void* b) {
+    const int key1 = static_cast<const SortableObject*>(a)->m_key;
+    const int key2 = static_cast<const SortableObject*>(b)->m_key;
+    if (key1 < key2) {
+        return -1;
+    } else if (key1 == key2) {
+        return 0;
+    } else {
+        return 1;
+    }
+}
+
+int calc_payload_for_pos(size_t pos) {
+    pos *= 231;
+    return pos ^ (pos << 8) ^ (pos << 16) ^ (pos << 24);
+}
+
+void shuffle_vec(Vector<SortableObject> &test_objects)
+{
+    for (size_t i = 0; i < test_objects.size() * 3; ++i) {
+        auto i1 = rand() % test_objects.size();
+        auto i2 = rand() % test_objects.size();
+        swap(test_objects[i1], test_objects[i2]);
+    }
+}
+
+int main()
+{
+    // Generate vector of SortableObjects in sorted order, with payloads determined by their sorted positions
+    Vector<SortableObject> test_objects;
+    for (auto i = 0; i < 1024; ++i) {
+        test_objects.append({i * 137, calc_payload_for_pos(i)});
+    }
+    for (size_t i = 0; i < NUM_RUNS; i++) {
+        // Shuffle the vector, then sort it again
+        shuffle_vec(test_objects);
+        qsort(test_objects.data(), test_objects.size(), sizeof(SortableObject), compare_sortable_object);
+        // Check that the objects are sorted by key
+        for (auto i = 0u; i + 1 < test_objects.size(); ++i) {
+            const auto &key1 = test_objects[i].m_key;
+            const auto &key2 = test_objects[i + 1].m_key;
+            if (key1 > key2) {
+                printf("\x1b[01;35mTests failed: saw key %d before key %d\n", key1, key2);
+                return 1;
+            }
+        }
+        // Check that the object's payloads have not been corrupted
+        for (auto i = 0u; i < test_objects.size(); ++i) {
+            const auto expected = calc_payload_for_pos(i);
+            const auto payload = test_objects[i].m_payload;
+            if (payload != expected) {
+                printf("\x1b[01;35mTests failed: expected payload %d for pos %u, got payload %d\n", expected, i, payload);
+                return 1;
+            }
+        }
+    }
+    printf("Tests succeeded\n");
+    return 0;
+}