Update version increment to wrap correctly. (#550)

* Update version increment to wrap correctly.

* Tests for issue549

* Added note to explain HandleVersionWrapAround test.

* Fixed style tab->spaces

src/bm_sim/match_units.cpp

@@ -986,7 +986,8 @@ MatchUnitGeneric<K, V>::delete_entry_(entry_handle_t handle) {
   Entry &entry = entries[handle_];
   if (HANDLE_VERSION(handle) != entry.key.version)
     return MatchErrorCode::EXPIRED_HANDLE;
-  entry.key.version += 1;
+  entry.key.version = HANDLE_VERSION(HANDLE_SET((entry.key.version + 1),
+                                                handle_));
   lookup_structure->delete_entry(entry.key);
 
   return this->unset_handle(handle_);

tests/test_tables.cpp

@@ -362,6 +362,23 @@ TYPED_TEST(TableSizeTwo, DeleteEntryHandleUpdate) {
   ASSERT_EQ(MatchErrorCode::EXPIRED_HANDLE, rc);
 }
 
+// This test was added for this issue:
+// https://github.com/p4lang/behavioral-model/issues/549.
+// Removing and entry increments the version field; the handle's version wraps
+// around, but the entry's did not.
+TYPED_TEST(TableSizeTwo, HandleVersionWrapAround) {
+  std::string key_ = "\xaa\xaa";
+  ByteContainer key("0xaaaa");
+  entry_handle_t handle;
+  MatchErrorCode rc;
+  for (unsigned int i = 0; i < 257; ++i) {
+    rc = this->add_entry(key_, &handle);
+    ASSERT_EQ(MatchErrorCode::SUCCESS, rc);
+    rc = this->table->delete_entry(handle);
+    ASSERT_EQ(MatchErrorCode::SUCCESS, rc);
+  }
+}
+
 TYPED_TEST(TableSizeTwo, LookupEntry) {
   std::string key_ = "\x0a\xba";
   ByteContainer key("0x0aba");