Abstract out the last remaining SQL queries in timer_retrieve_feeds()

feed_info.c

@@ -23,10 +23,24 @@ static const char *ZBLOCK_FEED_INFO_ERRORS[] = {
 	"Invalid arguments provided",
 	"An error was encountered with the feed database",
 	"The feed already exists",
-	"The feed does not exist"
+	"The feed does not exist",
+	"Finished getting feed info",
+	"Out of memory"
 };
 static_assert(sizeof(ZBLOCK_FEED_INFO_ERRORS) / sizeof(*ZBLOCK_FEED_INFO_ERRORS) == ZBLOCK_FEED_INFO_ERRORCOUNT, "Not all feed info errors implemented");
 
+// free all information associated with a minimal feed info struct (does not assume the struct was allocated using malloc)
+void zblock_feed_info_minimal_free(zblock_feed_info_minimal *feed_info) {
+	free(feed_info->last_pubDate);
+	free(feed_info->url);
+}
+
+// free all information associated with a feed info struct (does not assume the struct was allocated using malloc)
+void zblock_feed_info_free(zblock_feed_info *feed_info) {
+	free(feed_info->title);
+	zblock_feed_info_minimal_free((zblock_feed_info_minimal *) feed_info);
+}
+
 // returns a string about the result of a feed_info function
 const char *zblock_feed_info_strerror(zblock_feed_info_err error) {
 	return error < 0 || error >= ZBLOCK_FEED_INFO_ERRORCOUNT ? "Unspecified error" : ZBLOCK_FEED_INFO_ERRORS[error];
@@ -43,6 +57,49 @@ time_t pubDate_to_time_t(char *s) {
 	return timegm(&tm);
 }
 
+// Begin retrieval of feed info objects.
+zblock_feed_info_err zblock_feed_info_retrieve_list_begin(PGconn *conn) {
+	if (!conn) return ZBLOCK_FEED_INFO_INVALID_ARGS;
+
+	if (!PQsendQueryParams(
+		conn, "SELECT url, last_pubDate, channel_id from feeds",
+		0, NULL, NULL, NULL, NULL, 1
+	)) {
+		return ZBLOCK_FEED_INFO_DBERROR;
+	}
+	PQsetSingleRowMode(conn);
+	return ZBLOCK_FEED_INFO_OK;
+}
+
+// Retrieve the next feed list object.
+// On error, no more objects can be retrieved and the returned object is invalid.
+zblock_feed_info_err zblock_feed_info_retrieve_list_item(PGconn *conn, zblock_feed_info_minimal *feed_info) {
+	if (!conn || !feed_info) return ZBLOCK_FEED_INFO_INVALID_ARGS;
+
+	PGresult *res = PQgetResult(conn);
+	if (PQresultStatus(res) != PGRES_SINGLE_TUPLE) {
+		if (PQresultStatus(res) != PGRES_TUPLES_OK) {
+			log_error("Unable to retrieve feeds: %s", PQresultErrorMessage(res));	
+			PQclear(res);
+			return ZBLOCK_FEED_INFO_DBERROR;		
+		} else {
+			PQclear(res);
+			return ZBLOCK_FEED_INFO_FINISHED;		
+		}
+	}
+
+	feed_info->url = strdup(PQgetvalue(res, 0, 0));
+	feed_info->last_pubDate = strdup(PQgetvalue(res, 0, 1));
+	if (!feed_info->url || !feed_info->last_pubDate) {
+		PQclear(res);
+		return ZBLOCK_FEED_INFO_NOMEM;
+	}
+	feed_info->channel_id = be64toh(*(uint64_t *) PQgetvalue(res, 0, 2));
+	
+	PQclear(res);
+	return ZBLOCK_FEED_INFO_OK;
+}
+
 // check if the feed currently exists. the result is in the exists pointer.
 zblock_feed_info_err zblock_feed_info_exists(PGconn *conn, const char *url, u64snowflake channel_id, int *exists) {
 	if (!conn || !exists) return ZBLOCK_FEED_INFO_INVALID_ARGS;
@@ -149,11 +206,7 @@ zblock_feed_info_err zblock_feed_info_update(PGconn *conn, zblock_feed_info_mini
 	);
 	
 	zblock_feed_info_err result = ZBLOCK_FEED_INFO_OK;
-	if (PQresultStatus(update_res) != PGRES_COMMAND_OK) {
+	if (PQresultStatus(update_res) != PGRES_COMMAND_OK) result = ZBLOCK_FEED_INFO_DBERROR;
-		log_error("Failed to update feed: %s", PQresultErrorMessage(update_res));
-		result = ZBLOCK_FEED_INFO_DBERROR;
-	}
-	
 	PQclear(update_res);
 	return result;
 }

feed_info.h

@@ -27,15 +27,30 @@ typedef enum {
 	ZBLOCK_FEED_INFO_DBERROR,
 	ZBLOCK_FEED_INFO_EXISTS,
 	ZBLOCK_FEED_INFO_NOT_EXIST,
+	ZBLOCK_FEED_INFO_FINISHED,
+	ZBLOCK_FEED_INFO_NOMEM,
 	ZBLOCK_FEED_INFO_ERRORCOUNT
 } zblock_feed_info_err;
 
+// free all information associated with a minimal feed info struct (does not assume the struct was allocated using malloc)
+void zblock_feed_info_minimal_free(zblock_feed_info_minimal *feed_info);
+
+// free all information associated with a feed info struct (does not assume the struct was allocated using malloc)
+void zblock_feed_info_free(zblock_feed_info *feed_info);
+
 // maybe change the function signature so you can actually do error handling with the result?
 time_t pubDate_to_time_t(char *s);
 
 // returns a string about the result of a feed_info function
 const char *zblock_feed_info_strerror(zblock_feed_info_err error);
 
+// Begin retrieval of feed info objects.
+zblock_feed_info_err zblock_feed_info_retrieve_list_begin(PGconn *conn);
+
+// Retrieve the next feed list object.
+// On error, no more objects can be retrieved and the returned object is invalid.
+zblock_feed_info_err zblock_feed_info_retrieve_list_item(PGconn *conn, zblock_feed_info_minimal *feed_info);
+
 // check if the feed currently exists. the result is in the exists pointer.
 zblock_feed_info_err zblock_feed_info_exists(PGconn *conn, const char *url, u64snowflake channel_id, int *exists);
 

main.c

@@ -70,64 +70,40 @@ static void timer_retrieve_feeds(struct discord *client, struct discord_timer *t
 		return;
 	}
 
-	if (!PQsendQueryParams(
+	// Begin retrieval of feed list objects.
-		database_conn, "SELECT url, last_pubDate, channel_id from feeds",
+	if (zblock_feed_info_retrieve_list_begin(database_conn)) {
-		0, NULL, NULL, NULL, NULL, 1
-	)) {
 		log_error("Unable to retrieve feed list: %s", PQerrorMessage(database_conn));
+		curl_multi_cleanup(multi);
 		return;
 	}
-	PQsetSingleRowMode(database_conn);
 	
 	// put running handles up here so we can start transfers now instead of later
 	int running_handles, total_feeds = 0;
 	// get all the required feed info to send messages
-	PGresult *database_res;
+	zblock_feed_info_minimal feed_info;
-	while ((database_res = PQgetResult(database_conn))) {
+	while (!zblock_feed_info_retrieve_list_item(database_conn, &feed_info)) {
-		if (PQresultStatus(database_res) != PGRES_SINGLE_TUPLE) {
-			if (PQresultStatus(database_res) != PGRES_TUPLES_OK) {
-				log_error("Unable to retrieve feeds: %s", PQresultErrorMessage(database_res));			
-			}
-			goto db_loop_end;
-		}
-		
 		++total_feeds;
 		zblock_feed_buffer *feed_buffer = malloc(sizeof(*feed_buffer));
 		if (!feed_buffer) {
 			log_error("Failure allocating feed buffer: %s", strerror(errno));
-			goto db_loop_end;
+			continue;
 		}
-		feed_buffer->info.url = strdup(PQgetvalue(database_res, 0, 0));
+		feed_buffer->info = feed_info;
-		if (!feed_buffer->info.url) {
-			log_error("Failure allocating feed buffer: %s", strerror(errno));
-			free(feed_buffer);
-			goto db_loop_end;
-		}
-		feed_buffer->info.last_pubDate = strdup(PQgetvalue(database_res, 0, 1));
-		if (!feed_buffer->info.url) {
-			log_error("Failure allocating feed buffer: %s", strerror(errno));
-			free(feed_buffer->info.url);
-			free(feed_buffer);
-			goto db_loop_end;
-		}
-		feed_buffer->info.channel_id = be64toh(*(uint64_t *) PQgetvalue(database_res, 0, 2));
 		feed_buffer->fp = open_memstream(&feed_buffer->buf, &feed_buffer->bufsize);
 		if (!feed_buffer->fp) {
 			log_error("Unable to retrieve feed: %s", strerror(errno));
-			free(feed_buffer->info.last_pubDate);
+			zblock_feed_info_minimal_free(&feed_buffer->info);
-			free(feed_buffer->info.url);
 			free(feed_buffer);
-			goto db_loop_end;
+			continue;
 		}
 	
 		CURL *feed_handle = curl_easy_init();
 		if (!feed_handle) {
 			fclose(feed_buffer->fp);
 			free(feed_buffer->buf);
-			free(feed_buffer->info.last_pubDate);
+			zblock_feed_info_minimal_free(&feed_buffer->info);
-			free(feed_buffer->info.url);
 			free(feed_buffer);
-			goto db_loop_end;
+			continue;
 		}
 		
 		curl_easy_setopt(feed_handle, CURLOPT_URL, feed_buffer->info.url);
@@ -139,15 +115,11 @@ static void timer_retrieve_feeds(struct discord *client, struct discord_timer *t
 			curl_easy_cleanup(feed_handle);
 			fclose(feed_buffer->fp);
 			free(feed_buffer->buf);
-			free(feed_buffer->info.last_pubDate);
+			zblock_feed_info_minimal_free(&feed_buffer->info);
-			free(feed_buffer->info.url);
 			free(feed_buffer);
-			goto db_loop_end;
+			continue;
 		}
 		curl_multi_perform(multi, &running_handles);
-		
-		db_loop_end:
-		PQclear(database_res);
 	}
 	
 	int successful_feeds = 0;