coinbaser: Re-ask while a pooled split has fewer than 2 outputs

doc/example_datum_gateway_config.json

@@ -31,6 +31,7 @@
 		"migration_max_seconds": 86400,
 		"pool_pass_workers": true,
 		"pool_pass_full_users": true,
-		"pooled_mining_only": true
+		"pooled_mining_only": true,
+		"coinbaser_refetch": true
 	}
 }

src/datum_coinbaser.c

@@ -911,7 +911,14 @@ void *datum_coinbaser_thread(void *ptr) {
 				s->available_coinbase_outputs_count = 0;
 				i = 0;
 			}
-			if (i>=0) {
+			/* Pool mode only, and only when datum.coinbaser_refetch is true
+			 * (the default). A short list is not done: keep the current job
+			 * and ask again. Solo, or refetch disabled, publishes the local
+			 * one-output coinbase and stops asking. */
+			if (datum_config.datum_coinbaser_refetch && datum_protocol_is_active() && i < 2) {
+				DLOG_WARN("Coinbaser returned %d outputs (<2); not publishing one-output coinbase, will retry", i);
+				usleep(500000);
+			} else if (i>=0) {
 				DLOG_DEBUG("Generating coinbases for up to %d outputs", i);
 				generate_coinbase_txns_for_stratum_job(s, false);
 				if (__builtin_expect(atomic_load_explicit(&need_coinbaser_rwlocks_init_done, memory_order_acquire), 1)) {

src/datum_conf.c

@@ -198,6 +198,9 @@ const T_DATUM_CONFIG_ITEM datum_config_options[] = {
 	{ .var_type = DATUM_CONF_BOOL, 		.category = "datum", 		.name = "pooled_mining_only",			.description = "If the DATUM pool server becomes unavailable, terminate miner connections (otherwise, 100% of any blocks you find pay mining.pool_address)",
 		.example_default = true,
 		.required = false, .ptr = &datum_config.datum_pooled_mining_only, 	.default_bool = true },
+	{ .var_type = DATUM_CONF_BOOL, 		.category = "datum", 		.name = "coinbaser_refetch",			.description = "While connected to a DATUM pool, if a coinbaser answer has fewer than 2 outputs, keep the current job and ask again. Set false to publish the one-output coinbase and stop asking until the next job. Ignored when the pool link is down.",
+		.example_default = true,
+		.required = false, .ptr = &datum_config.datum_coinbaser_refetch, 	.default_bool = true },
 	{ .var_type = DATUM_CONF_INT, 		.category = "datum", 		.name = "protocol_global_timeout",		.description = "If no valid messages are received from the DATUM server in this many seconds, give up and try to reconnect",
 		.required = false, .ptr = &datum_config.datum_protocol_global_timeout, 	.default_int = 60 },
 };

src/datum_conf.h

@@ -170,6 +170,7 @@ typedef struct {
 	bool datum_pool_pass_workers;
 	bool datum_pool_pass_full_users;
 	bool datum_pooled_mining_only;
+	bool datum_coinbaser_refetch;
 	char datum_pool_pubkey[1024];
 	int datum_protocol_global_timeout;
 	uint64_t datum_protocol_global_timeout_ms;