Current mempools are kind of hybrid structures - they serve two
purposes:
1. mempool with a lock is basically static sized allocator with
pre-allocated free items
2. mempool without a lock is a doubly-linked list of preallocated items
The first kind of usage could be easily replaced with jemalloc small
sized arena objects and thread-local caches.
The second usage not-so-much and we need to keep this (in
libdns:message.c) for performance reasons.
remove redundant 'inst != NULL' test
162cleanup:
CID 281450 (#1 of 1): Dereference before null check (REVERSE_INULL)
check_after_deref: Null-checking inst suggests that it may be null, but it has already been dereferenced on all paths leading to the check.
163 if (result != ISC_R_SUCCESS && inst != NULL) {
164 plugin_destroy((void **)&inst);
165 }
the test-async plugin uses ns_query_hookasync() at the
NS_QUERY_DONE_SEND hook point to call an asynchronous function.
the only effect is to change the query response code to "NOTIMP",
so we can confirm that the hook ran and resumed correctly.
