BLI GHash: add some basic gtests.

We could likely add much more, but those already covers basic behavior and should be able
to catch most errors when editing this code.

Also added some performances tests as well (timing ghash insert/lookup under heavy loads,
for different kinds of keys).

1 files changed, 158 insertions, 0 deletions

diff --git a/tests/gtests/blenlib/BLI_ghash_test.cc b/tests/gtests/blenlib/BLI_ghash_test.cc
new file mode 100644
index 00000000000..5fe43d14cbe
--- /dev/null
+++ b/tests/gtests/blenlib/BLI_ghash_test.cc
@@ -0,0 +1,158 @@
+/* Apache License, Version 2.0 */
+
+#include "testing/testing.h"
+
+#define GHASH_INTERNAL_API
+
+extern "C" {
+#include "BLI_utildefines.h"
+#include "BLI_ghash.h"
+#include "BLI_rand.h"
+}
+
+#define TESTCASE_SIZE 10000
+
+/* Only keeping this in case here, for now. */
+#define PRINTF_GHASH_STATS(_gh) \
+{ \
+	double q, lf, var, pempty, poverloaded; \
+	int bigb; \
+	q = BLI_ghash_calc_quality_ex((_gh), &lf, &var, &pempty, &poverloaded, &bigb); \
+	printf("GHash stats (%d entries):\n\t" \
+	       "Quality (the lower the better): %f\n\tVariance (the lower the better): %f\n\tLoad: %f\n\t" \
+	       "Empty buckets: %.2f%%\n\tOverloaded buckets: %.2f%% (biggest bucket: %d)\n", \
+	       BLI_ghash_size(_gh), q, var, lf, pempty * 100.0, poverloaded * 100.0, bigb); \
+} void (0)
+
+/* Note: for pure-ghash testing, nature of the keys and data have absolutely no importance! So here we just use mere
+ *       random integers stored in pointers. */
+
+static void init_keys(unsigned int keys[TESTCASE_SIZE], const int seed)
+{
+	RNG *rng = BLI_rng_new(seed);
+	unsigned int *k;
+	int i;
+
+	for (i = 0, k = keys; i < TESTCASE_SIZE; ) {
+		/* Risks of collision are low, but they do exist.
+		 * And we cannot use a GSet, since we test that here! */
+		int j, t = BLI_rng_get_uint(rng);
+		for (j = i; j--; ) {
+			if (keys[j] == t) {
+				continue;
+			}
+		}
+		*k = t;
+		i++;
+		k++;
+	}
+	BLI_rng_free(rng);
+}
+
+/* Here we simply insert and then lookup all keys, ensuring we do get back the expected stored 'data'. */
+TEST(ghash, InsertLookup)
+{
+	GHash *ghash = BLI_ghash_new(BLI_ghashutil_inthash_p, BLI_ghashutil_intcmp, __func__);
+	unsigned int keys[TESTCASE_SIZE], *k;
+	int i;
+
+	init_keys(keys, 0);
+
+	for (i = TESTCASE_SIZE, k = keys; i--; k++) {
+		BLI_ghash_insert(ghash, SET_UINT_IN_POINTER(*k), SET_UINT_IN_POINTER(*k));
+	}
+
+	EXPECT_EQ(TESTCASE_SIZE, BLI_ghash_size(ghash));
+
+	for (i = TESTCASE_SIZE, k = keys; i--; k++) {
+		void *v = BLI_ghash_lookup(ghash, SET_UINT_IN_POINTER(*k));
+		EXPECT_EQ(*k, GET_UINT_FROM_POINTER(v));
+	}
+
+	BLI_ghash_free(ghash, NULL, NULL);
+}
+
+/* Here we simply insert and then remove all keys, ensuring we do get an empty, unshrinked ghash. */
+TEST(ghash, InsertRemove)
+{
+	GHash *ghash = BLI_ghash_new(BLI_ghashutil_inthash_p, BLI_ghashutil_intcmp, __func__);
+	unsigned int keys[TESTCASE_SIZE], *k;
+	int i, bkt_size;
+
+	init_keys(keys, 10);
+
+	for (i = TESTCASE_SIZE, k = keys; i--; k++) {
+		BLI_ghash_insert(ghash, SET_UINT_IN_POINTER(*k), SET_UINT_IN_POINTER(*k));
+	}
+
+	EXPECT_EQ(TESTCASE_SIZE, BLI_ghash_size(ghash));
+	bkt_size = BLI_ghash_buckets_size(ghash);
+
+	for (i = TESTCASE_SIZE, k = keys; i--; k++) {
+		void *v = BLI_ghash_popkey(ghash, SET_UINT_IN_POINTER(*k), NULL);
+		EXPECT_EQ(*k, GET_UINT_FROM_POINTER(v));
+	}
+
+	EXPECT_EQ(0, BLI_ghash_size(ghash));
+	EXPECT_EQ(bkt_size, BLI_ghash_buckets_size(ghash));
+
+	BLI_ghash_free(ghash, NULL, NULL);
+}
+
+/* Same as above, but this time we allow ghash to shrink. */
+TEST(ghash, InsertRemoveShrink)
+{
+	GHash *ghash = BLI_ghash_new(BLI_ghashutil_inthash_p, BLI_ghashutil_intcmp, __func__);
+	unsigned int keys[TESTCASE_SIZE], *k;
+	int i, bkt_size;
+
+	BLI_ghash_flag_set(ghash, GHASH_FLAG_ALLOW_SHRINK);
+	init_keys(keys, 20);
+
+	for (i = TESTCASE_SIZE, k = keys; i--; k++) {
+		BLI_ghash_insert(ghash, SET_UINT_IN_POINTER(*k), SET_UINT_IN_POINTER(*k));
+	}
+
+	EXPECT_EQ(TESTCASE_SIZE, BLI_ghash_size(ghash));
+	bkt_size = BLI_ghash_buckets_size(ghash);
+
+	for (i = TESTCASE_SIZE, k = keys; i--; k++) {
+		void *v = BLI_ghash_popkey(ghash, SET_UINT_IN_POINTER(*k), NULL);
+		EXPECT_EQ(*k, GET_UINT_FROM_POINTER(v));
+	}
+
+	EXPECT_EQ(0, BLI_ghash_size(ghash));
+	EXPECT_LT(BLI_ghash_buckets_size(ghash), bkt_size);
+
+	BLI_ghash_free(ghash, NULL, NULL);
+}
+
+/* Check copy. */
+TEST(ghash, Copy)
+{
+	GHash *ghash = BLI_ghash_new(BLI_ghashutil_inthash_p, BLI_ghashutil_intcmp, __func__);
+	GHash *ghash_copy;
+	unsigned int keys[TESTCASE_SIZE], *k;
+	int i;
+
+	init_keys(keys, 30);
+
+	for (i = TESTCASE_SIZE, k = keys; i--; k++) {
+		BLI_ghash_insert(ghash, SET_UINT_IN_POINTER(*k), SET_UINT_IN_POINTER(*k));
+	}
+
+	EXPECT_EQ(TESTCASE_SIZE, BLI_ghash_size(ghash));
+
+	ghash_copy = BLI_ghash_copy(ghash, NULL, NULL);
+
+	EXPECT_EQ(TESTCASE_SIZE, BLI_ghash_size(ghash_copy));
+	EXPECT_EQ(BLI_ghash_buckets_size(ghash), BLI_ghash_buckets_size(ghash_copy));
+
+	for (i = TESTCASE_SIZE, k = keys; i--; k++) {
+		void *v = BLI_ghash_lookup(ghash_copy, SET_UINT_IN_POINTER(*k));
+		EXPECT_EQ(*k, GET_UINT_FROM_POINTER(v));
+	}
+
+	BLI_ghash_free(ghash, NULL, NULL);
+	BLI_ghash_free(ghash_copy, NULL, NULL);
+}