Improve struct layouts for memory usage.

lib/mosquitto_internal.h

@@ -111,17 +111,17 @@ enum _mosquitto_transport {
 };
 
 struct _mosquitto_packet{
-	uint8_t command;
-	uint8_t have_remaining;
-	uint8_t remaining_count;
-	uint16_t mid;
+	uint8_t *payload;
+	struct _mosquitto_packet *next;
 	uint32_t remaining_mult;
 	uint32_t remaining_length;
 	uint32_t packet_length;
 	uint32_t to_process;
 	uint32_t pos;
-	uint8_t *payload;
-	struct _mosquitto_packet *next;
+	uint16_t mid;
+	uint8_t command;
+	uint8_t have_remaining;
+	uint8_t remaining_count;
 };
 
 struct mosquitto_message_all{
@@ -169,11 +169,11 @@ struct mosquitto {
 	char *tls_certfile;
 	char *tls_keyfile;
 	int (*tls_pw_callback)(char *buf, int size, int rwflag, void *userdata);
-	int tls_cert_reqs;
 	char *tls_version;
 	char *tls_ciphers;
 	char *tls_psk;
 	char *tls_psk_identity;
+	int tls_cert_reqs;
 	bool tls_insecure;
 #endif
 	bool want_write;
@@ -189,6 +189,7 @@ struct mosquitto {
 	pthread_t thread_id;
 #endif
 #ifdef WITH_BROKER
+	bool is_dropping;
 	bool is_bridge;
 	struct _mqtt3_bridge *bridge;
 	struct mosquitto_client_msg *msgs;
@@ -198,11 +199,10 @@ struct mosquitto {
 	struct _mosquitto_acl_user *acl_list;
 	struct _mqtt3_listener *listener;
 	time_t disconnect_t;
-	int pollfd_index;
 	struct _mosquitto_packet *out_packet_last;
-	bool is_dropping;
 	struct _mosquitto_subhier **subs;
 	int sub_count;
+	int pollfd_index;
 #  ifdef WITH_WEBSOCKETS
 	struct libwebsocket_context *ws_context;
 	struct libwebsocket *wsi;

src/database.c

@@ -455,39 +455,39 @@ int mqtt3_db_message_store(struct mosquitto_db *db, const char *source, uint16_t
 		return MOSQ_ERR_NOMEM;
 	}
 	temp->source_mid = source_mid;
-	temp->msg.mid = 0;
-	temp->msg.qos = qos;
-	temp->msg.retain = retain;
+	temp->mid = 0;
+	temp->qos = qos;
+	temp->retain = retain;
 	if(topic){
-		temp->msg.topic = _mosquitto_strdup(topic);
-		if(!temp->msg.topic){
+		temp->topic = _mosquitto_strdup(topic);
+		if(!temp->topic){
 			_mosquitto_free(temp->source_id);
 			_mosquitto_free(temp);
 			_mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Error: Out of memory.");
 			return MOSQ_ERR_NOMEM;
 		}
 	}else{
-		temp->msg.topic = NULL;
+		temp->topic = NULL;
 	}
-	temp->msg.payloadlen = payloadlen;
+	temp->payloadlen = payloadlen;
 	if(payloadlen){
-		temp->msg.payload = _mosquitto_malloc(sizeof(char)*payloadlen);
-		if(!temp->msg.payload){
+		temp->payload = _mosquitto_malloc(sizeof(char)*payloadlen);
+		if(!temp->payload){
 			if(temp->source_id) _mosquitto_free(temp->source_id);
-			if(temp->msg.topic) _mosquitto_free(temp->msg.topic);
-			if(temp->msg.payload) _mosquitto_free(temp->msg.payload);
+			if(temp->topic) _mosquitto_free(temp->topic);
+			if(temp->payload) _mosquitto_free(temp->payload);
 			_mosquitto_free(temp);
 			return MOSQ_ERR_NOMEM;
 		}
-		memcpy(temp->msg.payload, payload, sizeof(char)*payloadlen);
+		memcpy(temp->payload, payload, sizeof(char)*payloadlen);
 	}else{
-		temp->msg.payload = NULL;
+		temp->payload = NULL;
 	}
 
-	if(!temp->source_id || (payloadlen && !temp->msg.payload)){
+	if(!temp->source_id || (payloadlen && !temp->payload)){
 		if(temp->source_id) _mosquitto_free(temp->source_id);
-		if(temp->msg.topic) _mosquitto_free(temp->msg.topic);
-		if(temp->msg.payload) _mosquitto_free(temp->msg.payload);
+		if(temp->topic) _mosquitto_free(temp->topic);
+		if(temp->payload) _mosquitto_free(temp->payload);
 		_mosquitto_free(temp);
 		return 1;
 	}
@@ -687,8 +687,8 @@ int mqtt3_db_message_release(struct mosquitto_db *db, struct mosquitto *context,
 			}
 		}
 		if(tail->mid == mid && tail->direction == dir){
-			qos = tail->store->msg.qos;
-			topic = tail->store->msg.topic;
+			qos = tail->store->qos;
+			topic = tail->store->topic;
 			retain = tail->retain;
 			source_id = tail->store->source_id;
 
@@ -748,10 +748,10 @@ int mqtt3_db_message_write(struct mosquitto_db *db, struct mosquitto *context)
 			mid = tail->mid;
 			retries = tail->dup;
 			retain = tail->retain;
-			topic = tail->store->msg.topic;
+			topic = tail->store->topic;
 			qos = tail->qos;
-			payloadlen = tail->store->msg.payloadlen;
-			payload = tail->store->msg.payload;
+			payloadlen = tail->store->payloadlen;
+			payload = tail->store->payload;
 
 			switch(tail->state){
 				case mosq_ms_publish_qos0:

src/mosquitto_broker.h

@@ -144,21 +144,26 @@ struct _mosquitto_subhier {
 struct mosquitto_msg_store{
 	UT_hash_handle hh;
 	dbid_t db_id;
-	int ref_count;
 	char *source_id;
 	char **dest_ids;
 	int dest_id_count;
+	int ref_count;
+	char *topic;
+	void *payload;
+	uint32_t payloadlen;
 	uint16_t source_mid;
-	struct mosquitto_message msg;
+	uint16_t mid;
+	uint8_t qos;
+	bool retain;
 };
 
 struct mosquitto_client_msg{
 	struct mosquitto_client_msg *next;
 	struct mosquitto_msg_store *store;
+	time_t timestamp;
 	uint16_t mid;
-	int qos;
+	uint8_t qos;
 	bool retain;
-	time_t timestamp;
 	enum mosquitto_msg_direction direction;
 	enum mosquitto_msg_state state;
 	bool dup;
@@ -169,8 +174,8 @@ struct _mosquitto_unpwd{
 	char *password;
 #ifdef WITH_TLS
 	unsigned int password_len;
-	unsigned char *salt;
 	unsigned int salt_len;
+	unsigned char *salt;
 #endif
 	UT_hash_handle hh;
 };
@@ -261,8 +266,10 @@ struct _mqtt3_bridge{
 	int address_count;
 	time_t primary_retry;
 	bool round_robin;
-	int keepalive;
+	bool try_private;
+	bool try_private_accepted;
 	bool clean_session;
+	int keepalive;
 	struct _mqtt3_bridge_topic *topics;
 	int topic_count;
 	bool topic_remapping;
@@ -280,8 +287,6 @@ struct _mqtt3_bridge{
 	int restart_timeout;
 	int threshold;
 	bool lazy_reconnect;
-	bool try_private;
-	bool try_private_accepted;
 #ifdef WITH_TLS
 	char *tls_cafile;
 	char *tls_capath;

src/persist.c

@@ -138,7 +138,7 @@ static int mqtt3_db_message_store_write(struct mosquitto_db *db, FILE *db_fptr)
 	assert(db_fptr);
 
 	HASH_ITER(hh, db->msg_store, stored, stored_tmp){
-		if(!strncmp(stored->msg.topic, "$SYS", 4)){
+		if(!strncmp(stored->topic, "$SYS", 4)){
 			/* Don't save $SYS messages as retained otherwise they can give
 			 * misleading information when reloaded. They should still be saved
 			 * because a disconnected durable client may have them in their
@@ -149,8 +149,8 @@ static int mqtt3_db_message_store_write(struct mosquitto_db *db, FILE *db_fptr)
 		}
 		length = htonl(sizeof(dbid_t) + 2+strlen(stored->source_id) +
 				sizeof(uint16_t) + sizeof(uint16_t) +
-				2+strlen(stored->msg.topic) + sizeof(uint32_t) +
-				stored->msg.payloadlen + sizeof(uint8_t) + sizeof(uint8_t));
+				2+strlen(stored->topic) + sizeof(uint32_t) +
+				stored->payloadlen + sizeof(uint8_t) + sizeof(uint8_t));
 
 		i16temp = htons(DB_CHUNK_MSG_STORE);
 		write_e(db_fptr, &i16temp, sizeof(uint16_t));
@@ -169,28 +169,28 @@ static int mqtt3_db_message_store_write(struct mosquitto_db *db, FILE *db_fptr)
 		i16temp = htons(stored->source_mid);
 		write_e(db_fptr, &i16temp, sizeof(uint16_t));
 
-		i16temp = htons(stored->msg.mid);
+		i16temp = htons(stored->mid);
 		write_e(db_fptr, &i16temp, sizeof(uint16_t));
 
-		slen = strlen(stored->msg.topic);
+		slen = strlen(stored->topic);
 		i16temp = htons(slen);
 		write_e(db_fptr, &i16temp, sizeof(uint16_t));
-		write_e(db_fptr, stored->msg.topic, slen);
+		write_e(db_fptr, stored->topic, slen);
 
-		i8temp = (uint8_t )stored->msg.qos;
+		i8temp = (uint8_t )stored->qos;
 		write_e(db_fptr, &i8temp, sizeof(uint8_t));
 
 		if(force_no_retain == false){
-			i8temp = (uint8_t )stored->msg.retain;
+			i8temp = (uint8_t )stored->retain;
 		}else{
 			i8temp = 0;
 		}
 		write_e(db_fptr, &i8temp, sizeof(uint8_t));
 
-		i32temp = htonl(stored->msg.payloadlen);
+		i32temp = htonl(stored->payloadlen);
 		write_e(db_fptr, &i32temp, sizeof(uint32_t));
-		if(stored->msg.payloadlen){
-			write_e(db_fptr, stored->msg.payload, (unsigned int)stored->msg.payloadlen);
+		if(stored->payloadlen){
+			write_e(db_fptr, stored->payload, (unsigned int)stored->payloadlen);
 		}
 	}
 
@@ -284,7 +284,7 @@ static int _db_subs_retain_write(struct mosquitto_db *db, FILE *db_fptr, struct
 		sub = sub->next;
 	}
 	if(node->retained){
-		if(strncmp(node->retained->msg.topic, "$SYS", 4)){
+		if(strncmp(node->retained->topic, "$SYS", 4)){
 			/* Don't save $SYS messages. */
 			length = htonl(sizeof(dbid_t));
 
@@ -645,7 +645,7 @@ static int _db_retain_chunk_restore(struct mosquitto_db *db, FILE *db_fptr)
 	store_id = i64temp;
 	HASH_FIND(hh, db->msg_store, &store_id, sizeof(dbid_t), store);
 	if(store){
-		mqtt3_db_messages_queue(db, NULL, store->msg.topic, store->msg.qos, store->msg.retain, store);
+		mqtt3_db_messages_queue(db, NULL, store->topic, store->qos, store->retain, store);
 	}else{
 		_mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Error: Corrupt database whilst restoring a retained message.");
 		return MOSQ_ERR_INVAL;

src/read_handle_server.c

@@ -525,7 +525,7 @@ int mqtt3_handle_connect(struct mosquitto_db *db, struct mosquitto *context)
 	msg_prev = NULL;
 	while(msg_tail){
 		if(msg_tail->direction == mosq_md_out){
-			if(mosquitto_acl_check(db, context, msg_tail->store->msg.topic, MOSQ_ACL_READ) == MOSQ_ERR_ACL_DENIED){
+			if(mosquitto_acl_check(db, context, msg_tail->store->topic, MOSQ_ACL_READ) == MOSQ_ERR_ACL_DENIED){
 				msg_tail->store->ref_count--;
 				if(msg_prev){
 					msg_prev->next = msg_tail->next;

src/subs.c

@@ -89,7 +89,7 @@ static int _subs_process(struct mosquitto_db *db, struct _mosquitto_subhier *hie
 			db->retained_count--;
 #endif
 		}
-		if(stored->msg.payloadlen){
+		if(stored->payloadlen){
 			hier->retained = stored;
 			hier->retained->ref_count++;
 #ifdef WITH_SYS_TREE
@@ -618,14 +618,14 @@ static int _retain_process(struct mosquitto_db *db, struct mosquitto_msg_store *
 	int qos;
 	uint16_t mid;
 
-	rc = mosquitto_acl_check(db, context, retained->msg.topic, MOSQ_ACL_READ);
+	rc = mosquitto_acl_check(db, context, retained->topic, MOSQ_ACL_READ);
 	if(rc == MOSQ_ERR_ACL_DENIED){
 		return MOSQ_ERR_SUCCESS;
 	}else if(rc != MOSQ_ERR_SUCCESS){
 		return rc;
 	}
 
-	qos = retained->msg.qos;
+	qos = retained->qos;
 
 	if(qos > sub_qos) qos = sub_qos;
 	if(qos > 0){