DAOS-15120 crt: Misc d_rand-related fixes (#13738)

- Remove duplicate d_srand calls in crt.

  - Use tv_nsec instead of tv_nsec / 1e3 when calling d_srand, for this
    reduces the chance of seed collisions among daos_engine processes.

  - Replace rand calls in libgurt and libpool with d_rand.

  - Remove d_randn (introduced by this author), since lrand48_r doesn't
    return the lowest bits from Xi, and the % method is therefore
    sufficient for our purposes.

Signed-off-by: Li Wei <[email protected]>

src/cart/crt_init.c

@@ -9,7 +9,6 @@
  */
 #include <malloc.h>
 #include <sys/mman.h>
-#include <sys/time.h>
 #include <sys/resource.h>
 #include "crt_internal.h"
 
@@ -68,6 +67,7 @@ crt_lib_init(void)
 {
 	int		rc;
 	uint64_t	start_rpcid;
+	struct timespec	now;
 
 	rc = D_RWLOCK_INIT(&crt_gdata.cg_rwlock, NULL);
 	D_ASSERT(rc == 0);
@@ -82,7 +82,9 @@ crt_lib_init(void)
 	crt_gdata.cg_inited = 0;
 	crt_gdata.cg_primary_prov = CRT_PROV_OFI_TCP_RXM;
 
-	d_srand(d_timeus_secdiff(0) + getpid());
+	rc = d_gettime(&now);
+	D_ASSERTF(rc == 0, "d_gettime: " DF_RC "\n", DP_RC(rc));
+	d_srand(now.tv_sec * 1000 * 1000 * 1000 + now.tv_nsec + getpid());
 	start_rpcid = ((uint64_t)d_rand()) << 32;
 
 	crt_gdata.cg_rpcid = start_rpcid;
@@ -610,8 +612,6 @@ crt_init_opt(crt_group_id_t grpid, uint32_t flags, crt_init_options_t *opt)
 	char          *domain_env = NULL;
 	char          *auth_key;
 	char          *auth_key_env = NULL;
-	struct timeval now;
-	unsigned int   seed;
 	char          *path;
 	bool           server        = flags & CRT_FLAG_BIT_SERVER;
 	int            rc            = 0;
@@ -673,11 +673,6 @@ crt_init_opt(crt_group_id_t grpid, uint32_t flags, crt_init_options_t *opt)
 
 	D_RWLOCK_WRLOCK(&crt_gdata.cg_rwlock);
 	if (crt_gdata.cg_inited == 0) {
-		/* feed a seed for pseudo-random number generator */
-		gettimeofday(&now, NULL);
-		seed = (unsigned int)(now.tv_sec * 1000000 + now.tv_usec);
-		d_srand(seed);
-
 		crt_gdata.cg_server = server;
 		crt_gdata.cg_auto_swim_disable =
 			(flags & CRT_FLAG_BIT_AUTO_SWIM_DISABLE) ? 1 : 0;

src/common/rsvc.c

@@ -91,7 +91,7 @@ rsvc_client_choose(struct rsvc_client *client, crt_endpoint_t *ep)
 		chosen = client->sc_leader_index;
 	} else {
 		if (client->sc_next < 0)
-			client->sc_next = d_randn(client->sc_ranks->rl_nr);
+			client->sc_next = d_rand() % client->sc_ranks->rl_nr;
 		chosen = client->sc_next;
 		/* The hintless search is a round robin of all replicas. */
 		client->sc_next++;
@@ -148,7 +148,7 @@ rsvc_client_process_error(struct rsvc_client *client, int rc,
 			 * search.
 			 */
 			D_DEBUG(DB_MD, "give up leader rank %u\n", ep->ep_rank);
-			client->sc_next = d_randn(client->sc_ranks->rl_nr);
+			client->sc_next = d_rand() % client->sc_ranks->rl_nr;
 			if (client->sc_next == leader_index) {
 				client->sc_next++;
 				client->sc_next %= client->sc_ranks->rl_nr;

src/gurt/misc.c

@@ -57,19 +57,6 @@ d_rand()
 	return result;
 }
 
-/* Return a random integer in [0, n), where n must be positive. */
-long int
-d_randn(long int n)
-{
-	long int i;
-
-	D_ASSERT(n > 0);
-	i = ((double)d_rand() / D_RAND_MAX) * n;
-	if (i >= n)
-		i = 0;
-	return i;
-}
-
 /* Developer/debug version, poison memory on free.
  * This tries several ways to access the buffer size however none of them are perfect so for now
  * this is no in release builds.
@@ -544,7 +531,7 @@ d_rank_list_shuffle(d_rank_list_t *rank_list)
 		return;
 
 	for (i = 0; i < rank_list->rl_nr; i++) {
-		j = rand() % rank_list->rl_nr;
+		j = d_rand() % rank_list->rl_nr;
 		tmp = rank_list->rl_ranks[i];
 		rank_list->rl_ranks[i] = rank_list->rl_ranks[j];
 		rank_list->rl_ranks[j] = tmp;

src/include/gurt/common.h

@@ -82,7 +82,6 @@ extern "C" {
 
 void d_srand(long int);
 long int d_rand(void);
-long int d_randn(long int n);
 
 /* Instruct the compiler these are allocation functions that return a pointer, and if possible
  * which function needs to be used to free them.

src/pool/cli.c

@@ -1631,9 +1631,7 @@ choose_map_refresh_rank(struct map_refresh_arg *arg)
 
 	if (arg->mra_i == -1) {
 		/* Let i be a random integer in [0, n). */
-		i = ((double)rand() / RAND_MAX) * n;
-		if (i == n)
-			i = 0;
+		i = d_rand() % n;
 	} else {
 		/* Continue the round robin. */
 		i = arg->mra_i;

src/pool/srv_util.c

@@ -392,7 +392,7 @@ init_reconf_map(struct pool_map *map, d_rank_list_t *replicas, d_rank_t self,
 
 	/* Shuffle rmap.rcm_domains for randomness in replica placement. */
 	for (i = 0; i < rmap.rcm_domains_len; i++) {
-		int j = i + d_randn(rmap.rcm_domains_len - i);
+		int j = i + d_rand() % (rmap.rcm_domains_len - i);
 
 		D_ASSERTF(i <= j && j < rmap.rcm_domains_len, "i=%d j=%d len=%d\n", i, j,
 			  rmap.rcm_domains_len);
@@ -441,7 +441,7 @@ find_vacancy_in_domain(struct reconf_domain *rdomain, d_rank_list_t *replicas)
 		if ((engine->do_comp.co_status & POOL_SVC_MAP_STATES) &&
 		    !d_rank_list_find(replicas, engine->do_comp.co_rank, NULL /* idx */)) {
 			/* Pick this vacant engine with a probability of 1/n. */
-			if (d_randn(n) == 0)
+			if (d_rand() % n == 0)
 				return engine->do_comp.co_rank;
 			n--;
 		}
@@ -478,7 +478,7 @@ find_replica_in_domain(struct reconf_domain *rdomain, d_rank_list_t *replicas, d
 		if ((engine->do_comp.co_status & POOL_SVC_MAP_STATES) &&
 		    engine->do_comp.co_rank != self &&
 		    d_rank_list_find(replicas, engine->do_comp.co_rank, NULL /* idx */)) {
-			if (d_randn(n) == 0)
+			if (d_rand() % n == 0)
 				return engine->do_comp.co_rank;
 			n--;
 		}