idhash: add nng_id_visit API

This allows an efficient way to iterate over the entries
stored in an ID hash. The iteration is fast, and requires no
additional storage.  The order of iteration is not guaranteed.

1 files changed, 48 insertions, 0 deletions

diff --git a/src/supplemental/util/idhash_test.c b/src/supplemental/util/idhash_test.c
index 5bbdc4fb..e0d472a0 100644
--- a/src/supplemental/util/idhash_test.c
+++ b/src/supplemental/util/idhash_test.c
@@ -182,6 +182,52 @@ test_id_set_out_of_range(void)
 	nng_id_map_free(m);
 }
 
+void
+test_id_visit(void)
+{
+	nng_id_map *m;
+	int         x, y;
+	uint64_t    id1;
+	uint64_t    id2;
+	int        *v1;
+	int        *v2;
+	uint32_t    cursor = 0;
+
+	NUTS_PASS(nng_id_map_alloc(&m, 10, 13, 0));
+
+	// We can insert outside the range forcibly.
+	NUTS_PASS(nng_id_set(m, 1, &x));
+	NUTS_PASS(nng_id_set(m, 100, &y));
+	NUTS_TRUE(nng_id_visit(m, &id1, (void **) &v1, &cursor));
+	NUTS_ASSERT(id1 == 1 || id1 == 100);
+	NUTS_ASSERT(v1 == &x || v1 == &y);
+	NUTS_TRUE(nng_id_visit(m, &id2, (void **) &v2, &cursor));
+	NUTS_ASSERT(id2 == 1 || id2 == 100);
+	NUTS_ASSERT(v2 == &x || v2 == &y);
+	NUTS_ASSERT(id1 != id2);
+	NUTS_ASSERT(v1 != v2);
+	NUTS_TRUE(!nng_id_visit(m, &id2, (void **) &v2, &cursor));
+	nng_id_map_free(m);
+}
+
+void
+test_id_visit_out_of_range(void)
+{
+	nng_id_map *m;
+	int         x, y;
+	uint64_t    id1;
+	int        *v1;
+	uint32_t    cursor = 1000;
+
+	NUTS_PASS(nng_id_map_alloc(&m, 10, 13, 0));
+
+	// We can insert outside the range forcibly.
+	NUTS_PASS(nng_id_set(m, 1, &x));
+	NUTS_PASS(nng_id_set(m, 100, &y));
+	NUTS_TRUE(!nng_id_visit(m, &id1, (void **) &v1, &cursor));
+	nng_id_map_free(m);
+}
+
 #define STRESS_LOAD 50000
 #define NUM_VALUES 1000
 
@@ -303,6 +349,8 @@ NUTS_TESTS = {
 	{ "id resize", test_id_resize },
 	{ "id dynamic", test_id_dynamic },
 	{ "id set out of range", test_id_set_out_of_range },
+	{ "id visit", test_id_visit },
+	{ "id visit out of range", test_id_visit_out_of_range },
 	{ "id stress", test_id_stress },
 	{ "id alloc long long", test_id_alloc_long_long },
 	{ NULL, NULL },