hbitmap: truncate tests

The general approach is to set bits close to the boundaries of
where we are truncating and ensure that everything appears to
have gone OK.

We test growing and shrinking by different amounts:
- Less than the granularity
- Less than the granularity, but across a boundary
- Less than sizeof(unsigned long)
- Less than sizeof(unsigned long), but across a ulong boundary
- More than sizeof(unsigned long)

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1429314609-29776-17-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

tests/test-hbitmap.c

@@ -11,6 +11,8 @@
 
 #include <glib.h>
 #include <stdarg.h>
+#include <string.h>
+#include <sys/types.h>
 #include "qemu/hbitmap.h"
 
 #define LOG_BITS_PER_LONG          (BITS_PER_LONG == 32 ? 5 : 6)
@@ -23,6 +25,7 @@ typedef struct TestHBitmapData {
     HBitmap       *hb;
     unsigned long *bits;
     size_t         size;
+    size_t         old_size;
     int            granularity;
 } TestHBitmapData;
 
@@ -91,6 +94,44 @@ static void hbitmap_test_init(TestHBitmapData *data,
     }
 }
 
+static inline size_t hbitmap_test_array_size(size_t bits)
+{
+    size_t n = (bits + BITS_PER_LONG - 1) / BITS_PER_LONG;
+    return n ? n : 1;
+}
+
+static void hbitmap_test_truncate_impl(TestHBitmapData *data,
+                                       size_t size)
+{
+    size_t n;
+    size_t m;
+    data->old_size = data->size;
+    data->size = size;
+
+    if (data->size == data->old_size) {
+        return;
+    }
+
+    n = hbitmap_test_array_size(size);
+    m = hbitmap_test_array_size(data->old_size);
+    data->bits = g_realloc(data->bits, sizeof(unsigned long) * n);
+    if (n > m) {
+        memset(&data->bits[m], 0x00, sizeof(unsigned long) * (n - m));
+    }
+
+    /* If we shrink to an uneven multiple of sizeof(unsigned long),
+     * scrub the leftover memory. */
+    if (data->size < data->old_size) {
+        m = size % (sizeof(unsigned long) * 8);
+        if (m) {
+            unsigned long mask = (1ULL << m) - 1;
+            data->bits[n-1] &= mask;
+        }
+    }
+
+    hbitmap_truncate(data->hb, size);
+}
+
 static void hbitmap_test_teardown(TestHBitmapData *data,
                                   const void *unused)
 {
@@ -369,6 +410,198 @@ static void test_hbitmap_iter_granularity(TestHBitmapData *data,
     g_assert_cmpint(hbitmap_iter_next(&hbi), <, 0);
 }
 
+static void hbitmap_test_set_boundary_bits(TestHBitmapData *data, ssize_t diff)
+{
+    size_t size = data->size;
+
+    /* First bit */
+    hbitmap_test_set(data, 0, 1);
+    if (diff < 0) {
+        /* Last bit in new, shortened map */
+        hbitmap_test_set(data, size + diff - 1, 1);
+
+        /* First bit to be truncated away */
+        hbitmap_test_set(data, size + diff, 1);
+    }
+    /* Last bit */
+    hbitmap_test_set(data, size - 1, 1);
+    if (data->granularity == 0) {
+        hbitmap_test_check_get(data);
+    }
+}
+
+static void hbitmap_test_check_boundary_bits(TestHBitmapData *data)
+{
+    size_t size = MIN(data->size, data->old_size);
+
+    if (data->granularity == 0) {
+        hbitmap_test_check_get(data);
+        hbitmap_test_check(data, 0);
+    } else {
+        /* If a granularity was set, note that every distinct
+         * (bit >> granularity) value that was set will increase
+         * the bit pop count by 2^granularity, not just 1.
+         *
+         * The hbitmap_test_check facility does not currently tolerate
+         * non-zero granularities, so test the boundaries and the population
+         * count manually.
+         */
+        g_assert(hbitmap_get(data->hb, 0));
+        g_assert(hbitmap_get(data->hb, size - 1));
+        g_assert_cmpint(2 << data->granularity, ==, hbitmap_count(data->hb));
+    }
+}
+
+/* Generic truncate test. */
+static void hbitmap_test_truncate(TestHBitmapData *data,
+                                  size_t size,
+                                  ssize_t diff,
+                                  int granularity)
+{
+    hbitmap_test_init(data, size, granularity);
+    hbitmap_test_set_boundary_bits(data, diff);
+    hbitmap_test_truncate_impl(data, size + diff);
+    hbitmap_test_check_boundary_bits(data);
+}
+
+static void test_hbitmap_truncate_nop(TestHBitmapData *data,
+                                      const void *unused)
+{
+    hbitmap_test_truncate(data, L2, 0, 0);
+}
+
+/**
+ * Grow by an amount smaller than the granularity, without crossing
+ * a granularity alignment boundary. Effectively a NOP.
+ */
+static void test_hbitmap_truncate_grow_negligible(TestHBitmapData *data,
+                                                  const void *unused)
+{
+    size_t size = L2 - 1;
+    size_t diff = 1;
+    int granularity = 1;
+
+    hbitmap_test_truncate(data, size, diff, granularity);
+}
+
+/**
+ * Shrink by an amount smaller than the granularity, without crossing
+ * a granularity alignment boundary. Effectively a NOP.
+ */
+static void test_hbitmap_truncate_shrink_negligible(TestHBitmapData *data,
+                                                    const void *unused)
+{
+    size_t size = L2;
+    ssize_t diff = -1;
+    int granularity = 1;
+
+    hbitmap_test_truncate(data, size, diff, granularity);
+}
+
+/**
+ * Grow by an amount smaller than the granularity, but crossing over
+ * a granularity alignment boundary.
+ */
+static void test_hbitmap_truncate_grow_tiny(TestHBitmapData *data,
+                                            const void *unused)
+{
+    size_t size = L2 - 2;
+    ssize_t diff = 1;
+    int granularity = 1;
+
+    hbitmap_test_truncate(data, size, diff, granularity);
+}
+
+/**
+ * Shrink by an amount smaller than the granularity, but crossing over
+ * a granularity alignment boundary.
+ */
+static void test_hbitmap_truncate_shrink_tiny(TestHBitmapData *data,
+                                              const void *unused)
+{
+    size_t size = L2 - 1;
+    ssize_t diff = -1;
+    int granularity = 1;
+
+    hbitmap_test_truncate(data, size, diff, granularity);
+}
+
+/**
+ * Grow by an amount smaller than sizeof(long), and not crossing over
+ * a sizeof(long) alignment boundary.
+ */
+static void test_hbitmap_truncate_grow_small(TestHBitmapData *data,
+                                             const void *unused)
+{
+    size_t size = L2 + 1;
+    size_t diff = sizeof(long) / 2;
+
+    hbitmap_test_truncate(data, size, diff, 0);
+}
+
+/**
+ * Shrink by an amount smaller than sizeof(long), and not crossing over
+ * a sizeof(long) alignment boundary.
+ */
+static void test_hbitmap_truncate_shrink_small(TestHBitmapData *data,
+                                               const void *unused)
+{
+    size_t size = L2;
+    size_t diff = sizeof(long) / 2;
+
+    hbitmap_test_truncate(data, size, -diff, 0);
+}
+
+/**
+ * Grow by an amount smaller than sizeof(long), while crossing over
+ * a sizeof(long) alignment boundary.
+ */
+static void test_hbitmap_truncate_grow_medium(TestHBitmapData *data,
+                                              const void *unused)
+{
+    size_t size = L2 - 1;
+    size_t diff = sizeof(long) / 2;
+
+    hbitmap_test_truncate(data, size, diff, 0);
+}
+
+/**
+ * Shrink by an amount smaller than sizeof(long), while crossing over
+ * a sizeof(long) alignment boundary.
+ */
+static void test_hbitmap_truncate_shrink_medium(TestHBitmapData *data,
+                                                const void *unused)
+{
+    size_t size = L2 + 1;
+    size_t diff = sizeof(long) / 2;
+
+    hbitmap_test_truncate(data, size, -diff, 0);
+}
+
+/**
+ * Grow by an amount larger than sizeof(long).
+ */
+static void test_hbitmap_truncate_grow_large(TestHBitmapData *data,
+                                             const void *unused)
+{
+    size_t size = L2;
+    size_t diff = 8 * sizeof(long);
+
+    hbitmap_test_truncate(data, size, diff, 0);
+}
+
+/**
+ * Shrink by an amount larger than sizeof(long).
+ */
+static void test_hbitmap_truncate_shrink_large(TestHBitmapData *data,
+                                               const void *unused)
+{
+    size_t size = L2;
+    size_t diff = 8 * sizeof(long);
+
+    hbitmap_test_truncate(data, size, -diff, 0);
+}
+
 static void hbitmap_test_add(const char *testpath,
                                    void (*test_func)(TestHBitmapData *data, const void *user_data))
 {
@@ -395,6 +628,28 @@ int main(int argc, char **argv)
     hbitmap_test_add("/hbitmap/reset/empty", test_hbitmap_reset_empty);
     hbitmap_test_add("/hbitmap/reset/general", test_hbitmap_reset);
     hbitmap_test_add("/hbitmap/granularity", test_hbitmap_granularity);
+
+    hbitmap_test_add("/hbitmap/truncate/nop", test_hbitmap_truncate_nop);
+    hbitmap_test_add("/hbitmap/truncate/grow/negligible",
+                     test_hbitmap_truncate_grow_negligible);
+    hbitmap_test_add("/hbitmap/truncate/shrink/negligible",
+                     test_hbitmap_truncate_shrink_negligible);
+    hbitmap_test_add("/hbitmap/truncate/grow/tiny",
+                     test_hbitmap_truncate_grow_tiny);
+    hbitmap_test_add("/hbitmap/truncate/shrink/tiny",
+                     test_hbitmap_truncate_shrink_tiny);
+    hbitmap_test_add("/hbitmap/truncate/grow/small",
+                     test_hbitmap_truncate_grow_small);
+    hbitmap_test_add("/hbitmap/truncate/shrink/small",
+                     test_hbitmap_truncate_shrink_small);
+    hbitmap_test_add("/hbitmap/truncate/grow/medium",
+                     test_hbitmap_truncate_grow_medium);
+    hbitmap_test_add("/hbitmap/truncate/shrink/medium",
+                     test_hbitmap_truncate_shrink_medium);
+    hbitmap_test_add("/hbitmap/truncate/grow/large",
+                     test_hbitmap_truncate_grow_large);
+    hbitmap_test_add("/hbitmap/truncate/shrink/large",
+                     test_hbitmap_truncate_shrink_large);
     g_test_run();
 
     return 0;