BLI: New Edgehash and EdgeSet implementation

The new data structure uses open addressing instead of chaining to resolve collisions in the hash table.

This new structure was never slower than the old implementation in my tests. Code that first inserts all edges and then iterates through all edges (e.g. to remove duplicates) benefits the most, because the `EdgeHashIterator` becomes a simple for loop over a continuous array.

Reviewer: campbellbarton

Differential Revision: D4050

2 files changed, 406 insertions, 0 deletions

diff --git a/tests/gtests/blenlib/BLI_edgehash_test.cc b/tests/gtests/blenlib/BLI_edgehash_test.cc
new file mode 100644
index 00000000000..a9771d50c92
--- /dev/null
+++ b/tests/gtests/blenlib/BLI_edgehash_test.cc
@@ -0,0 +1,405 @@
+/* Apache License, Version 2.0 */
+
+#include "testing/testing.h"
+#include <vector>
+#include <algorithm>
+
+extern "C" {
+#include "BLI_utildefines.h"
+#include "BLI_edgehash.h"
+}
+
+#define VALUE_1 POINTER_FROM_INT(1)
+#define VALUE_2 POINTER_FROM_INT(2)
+#define VALUE_3 POINTER_FROM_INT(3)
+
+TEST(edgehash, InsertIncreasesLength)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	ASSERT_EQ(BLI_edgehash_len(eh), 0);
+	BLI_edgehash_insert(eh, 1, 2, VALUE_1);
+	ASSERT_EQ(BLI_edgehash_len(eh), 1);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, ReinsertNewIncreasesLength)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	ASSERT_EQ(BLI_edgehash_len(eh), 0);
+	BLI_edgehash_reinsert(eh, 1, 2, VALUE_1);
+	ASSERT_EQ(BLI_edgehash_len(eh), 1);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, ReinsertExistingDoesNotIncreaseLength)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	ASSERT_EQ(BLI_edgehash_len(eh), 0);
+	BLI_edgehash_reinsert(eh, 1, 2, VALUE_1);
+	ASSERT_EQ(BLI_edgehash_len(eh), 1);
+	BLI_edgehash_reinsert(eh, 1, 2, VALUE_2);
+	ASSERT_EQ(BLI_edgehash_len(eh), 1);
+	BLI_edgehash_reinsert(eh, 2, 1, VALUE_2);
+	ASSERT_EQ(BLI_edgehash_len(eh), 1);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, ReinsertCanChangeValue)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	BLI_edgehash_insert(eh, 1, 2, VALUE_1);
+	ASSERT_EQ(BLI_edgehash_lookup(eh, 1, 2), VALUE_1);
+	BLI_edgehash_reinsert(eh, 2, 1, VALUE_2);
+	ASSERT_EQ(BLI_edgehash_lookup(eh, 1, 2), VALUE_2);
+	BLI_edgehash_reinsert(eh, 1, 2, VALUE_3);
+	ASSERT_EQ(BLI_edgehash_lookup(eh, 2, 1), VALUE_3);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, LookupExisting)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	BLI_edgehash_insert(eh, 1, 2, VALUE_1);
+	ASSERT_EQ(BLI_edgehash_lookup(eh, 1, 2), VALUE_1);
+	ASSERT_EQ(BLI_edgehash_lookup(eh, 2, 1), VALUE_1);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, LookupNonExisting)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	ASSERT_EQ(BLI_edgehash_lookup(eh, 1, 2), nullptr);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, LookupNonExistingWithDefault)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	ASSERT_EQ(BLI_edgehash_lookup_default(eh, 1, 2, VALUE_1), VALUE_1);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, LookupExistingWithDefault)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	BLI_edgehash_insert(eh, 1, 2, VALUE_1);
+	ASSERT_EQ(BLI_edgehash_lookup_default(eh, 1, 2, VALUE_2), VALUE_1);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, LookupPExisting)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	void *value = VALUE_1;
+	BLI_edgehash_insert(eh, 1, 2, value);
+	void **value_p = BLI_edgehash_lookup_p(eh, 1, 2);
+	ASSERT_EQ(*value_p, VALUE_1);
+	*value_p = VALUE_2;
+	ASSERT_EQ(BLI_edgehash_lookup(eh, 1, 2), VALUE_2);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, LookupPNonExisting)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	ASSERT_EQ(BLI_edgehash_lookup_p(eh, 1, 2), nullptr);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, EnsurePNonExisting)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	void **value_p;
+	bool existed = BLI_edgehash_ensure_p(eh, 1, 2, &value_p);
+	ASSERT_FALSE(existed);
+	*value_p = VALUE_1;
+	ASSERT_EQ(BLI_edgehash_lookup(eh, 1, 2), VALUE_1);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, EnsurePExisting)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	BLI_edgehash_insert(eh, 1, 2, VALUE_1);
+	void **value_p;
+	bool existed = BLI_edgehash_ensure_p(eh, 1, 2, &value_p);
+	ASSERT_TRUE(existed);
+	ASSERT_EQ(*value_p, VALUE_1);
+	*value_p = VALUE_2;
+	ASSERT_EQ(BLI_edgehash_lookup(eh, 1, 2), VALUE_2);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, RemoveExistingDecreasesLength)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	BLI_edgehash_insert(eh, 1, 2, VALUE_1);
+	ASSERT_EQ(BLI_edgehash_len(eh), 1);
+	bool has_been_removed = BLI_edgehash_remove(eh, 1, 2, nullptr);
+	ASSERT_EQ(BLI_edgehash_len(eh), 0);
+	ASSERT_TRUE(has_been_removed);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, RemoveNonExistingDoesNotDecreaseLength)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	BLI_edgehash_insert(eh, 1, 2, VALUE_1);
+	ASSERT_EQ(BLI_edgehash_len(eh), 1);
+	bool has_been_removed = BLI_edgehash_remove(eh, 4, 5, nullptr);
+	ASSERT_EQ(BLI_edgehash_len(eh), 1);
+	ASSERT_FALSE(has_been_removed);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, PopKeyTwice)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	BLI_edgehash_insert(eh, 1, 2, VALUE_1);
+	ASSERT_EQ(BLI_edgehash_popkey(eh, 1, 2), VALUE_1);
+	ASSERT_EQ(BLI_edgehash_popkey(eh, 1, 2), nullptr);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, LookupInvertedIndices)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	BLI_edgehash_insert(eh, 1, 2, VALUE_1);
+	ASSERT_EQ(BLI_edgehash_lookup(eh, 2, 1), VALUE_1);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, HasKeyExisting)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	BLI_edgehash_insert(eh, 1, 2, VALUE_1);
+	ASSERT_TRUE(BLI_edgehash_haskey(eh, 1, 2));
+	ASSERT_TRUE(BLI_edgehash_haskey(eh, 2, 1));
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, HasKeyNonExisting)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	ASSERT_FALSE(BLI_edgehash_haskey(eh, 1, 2));
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, ClearSetsLengthToZero)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	BLI_edgehash_insert(eh, 1, 2, VALUE_1);
+	BLI_edgehash_insert(eh, 1, 2, VALUE_2);
+	ASSERT_EQ(BLI_edgehash_len(eh), 2);
+	BLI_edgehash_clear(eh, nullptr);
+	ASSERT_EQ(BLI_edgehash_len(eh), 0);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, IteratorFindsAllValues)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	BLI_edgehash_insert(eh, 1, 2, VALUE_1);
+	BLI_edgehash_insert(eh, 1, 3, VALUE_2);
+	BLI_edgehash_insert(eh, 1, 4, VALUE_3);
+
+	EdgeHashIterator *ehi = BLI_edgehashIterator_new(eh);
+	auto a = BLI_edgehashIterator_getValue(ehi);
+	BLI_edgehashIterator_step(ehi);
+	auto b = BLI_edgehashIterator_getValue(ehi);
+	BLI_edgehashIterator_step(ehi);
+	auto c = BLI_edgehashIterator_getValue(ehi);
+	BLI_edgehashIterator_step(ehi);
+
+	ASSERT_NE(a, b);
+	ASSERT_NE(b, c);
+	ASSERT_NE(a, c);
+	ASSERT_TRUE(ELEM(a, VALUE_1, VALUE_2, VALUE_3));
+	ASSERT_TRUE(ELEM(b, VALUE_1, VALUE_2, VALUE_3));
+	ASSERT_TRUE(ELEM(c, VALUE_1, VALUE_2, VALUE_3));
+
+	BLI_edgehashIterator_free(ehi);
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, IterateIsDone)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	BLI_edgehash_insert(eh, 1, 2, VALUE_1);
+	BLI_edgehash_insert(eh, 1, 3, VALUE_2);
+	BLI_edgehash_insert(eh, 1, 4, VALUE_3);
+
+	EdgeHashIterator *ehi = BLI_edgehashIterator_new(eh);
+	ASSERT_FALSE(BLI_edgehashIterator_isDone(ehi));
+	BLI_edgehashIterator_step(ehi);
+	ASSERT_FALSE(BLI_edgehashIterator_isDone(ehi));
+	BLI_edgehashIterator_step(ehi);
+	ASSERT_FALSE(BLI_edgehashIterator_isDone(ehi));
+	BLI_edgehashIterator_step(ehi);
+	ASSERT_TRUE(BLI_edgehashIterator_isDone(ehi));
+
+	BLI_edgehashIterator_free(ehi);
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgehash, DoubleRemove)
+{
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	BLI_edgehash_insert(eh, 1, 2, VALUE_1);
+	BLI_edgehash_insert(eh, 1, 3, VALUE_2);
+	BLI_edgehash_insert(eh, 1, 4, VALUE_3);
+	ASSERT_EQ(BLI_edgehash_len(eh), 3);
+
+	BLI_edgehash_remove(eh, 1, 2, nullptr);
+	BLI_edgehash_remove(eh, 1, 3, nullptr);
+	ASSERT_EQ(BLI_edgehash_len(eh), 1);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+struct Edge {
+	uint v1, v2;
+};
+
+TEST(edgehash, StressTest)
+{
+	std::srand(0);
+	int amount = 10000;
+
+	std::vector<Edge> edges;
+	for (int i = 0; i < amount; i++) {
+		edges.push_back({(uint)i, amount + (uint)std::rand() % 12345});
+	}
+
+	EdgeHash *eh = BLI_edgehash_new(__func__);
+
+	/* first insert all the edges */
+	for (int i = 0; i < edges.size(); i++) {
+		BLI_edgehash_insert(eh, edges[i].v1, edges[i].v2, POINTER_FROM_INT(i));
+	}
+
+	std::vector<Edge> shuffled = edges;
+	std::random_shuffle(shuffled.begin(), shuffled.end());
+
+	/* then remove half of them */
+	int remove_until = shuffled.size() / 2;
+	for (int i = 0; i < remove_until; i++) {
+		BLI_edgehash_remove(eh, shuffled[i].v2, shuffled[i].v1, nullptr);
+	}
+
+	ASSERT_EQ(BLI_edgehash_len(eh), edges.size() - remove_until);
+
+	/* check if the right ones have been removed */
+	for (int i = 0; i < shuffled.size(); i++) {
+		bool haskey = BLI_edgehash_haskey(eh, shuffled[i].v1, shuffled[i].v2);
+		if (i < remove_until) ASSERT_FALSE(haskey);
+		else                  ASSERT_TRUE(haskey);
+	}
+
+	/* reinsert all edges */
+	for (int i = 0; i < edges.size(); i++) {
+		BLI_edgehash_reinsert(eh, edges[i].v1, edges[i].v2, POINTER_FROM_INT(i));
+	}
+
+	ASSERT_EQ(BLI_edgehash_len(eh), edges.size());
+
+	/* pop all edges */
+	for (int i = 0; i < edges.size(); i++) {
+		int value = POINTER_AS_INT(BLI_edgehash_popkey(eh, edges[i].v1, edges[i].v2));
+		ASSERT_EQ(i, value);
+	}
+
+	ASSERT_EQ(BLI_edgehash_len(eh), 0);
+
+	BLI_edgehash_free(eh, nullptr);
+}
+
+TEST(edgeset, AddNonExistingIncreasesLength)
+{
+	EdgeSet *es = BLI_edgeset_new(__func__);
+
+	ASSERT_EQ(BLI_edgeset_len(es), 0);
+	BLI_edgeset_add(es, 1, 2);
+	ASSERT_EQ(BLI_edgeset_len(es), 1);
+	BLI_edgeset_add(es, 1, 3);
+	ASSERT_EQ(BLI_edgeset_len(es), 2);
+	BLI_edgeset_add(es, 1, 4);
+	ASSERT_EQ(BLI_edgeset_len(es), 3);
+
+	BLI_edgeset_free(es);
+}
+
+TEST(edgeset, AddExistingDoesNotIncreaseLength)
+{
+	EdgeSet *es = BLI_edgeset_new(__func__);
+
+	ASSERT_EQ(BLI_edgeset_len(es), 0);
+	BLI_edgeset_add(es, 1, 2);
+	ASSERT_EQ(BLI_edgeset_len(es), 1);
+	BLI_edgeset_add(es, 2, 1);
+	ASSERT_EQ(BLI_edgeset_len(es), 1);
+	BLI_edgeset_add(es, 1, 2);
+	ASSERT_EQ(BLI_edgeset_len(es), 1);
+
+	BLI_edgeset_free(es);
+}
+
+TEST(edgeset, HasKeyNonExisting)
+{
+	EdgeSet *es = BLI_edgeset_new(__func__);
+
+	ASSERT_FALSE(BLI_edgeset_haskey(es, 1, 2));
+
+	BLI_edgeset_free(es);
+}
+
+TEST(edgeset, HasKeyExisting)
+{
+	EdgeSet *es = BLI_edgeset_new(__func__);
+
+	BLI_edgeset_insert(es, 1, 2);
+	ASSERT_TRUE(BLI_edgeset_haskey(es, 1, 2));
+
+	BLI_edgeset_free(es);
+}
diff --git a/tests/gtests/blenlib/CMakeLists.txt b/tests/gtests/blenlib/CMakeLists.txt
index e399d4651f5..277dfd7afe1 100644
--- a/tests/gtests/blenlib/CMakeLists.txt
+++ b/tests/gtests/blenlib/CMakeLists.txt
@@ -44,6 +44,7 @@ endif()
 BLENDER_TEST(BLI_array_store "bf_blenlib")
 BLENDER_TEST(BLI_array_utils "bf_blenlib")
 BLENDER_TEST(BLI_expr_pylike_eval "bf_blenlib")
+BLENDER_TEST(BLI_edgehash "bf_blenlib")
 BLENDER_TEST(BLI_ghash "bf_blenlib")
 BLENDER_TEST(BLI_hash_mm2a "bf_blenlib")
 BLENDER_TEST(BLI_heap "bf_blenlib")