From 8c59a5b0d397f78609cfab35db7923b9d6b8c08a Mon Sep 17 00:00:00 2001
From: Rafal Pietruch <r.pietruch@samsung.com>
Date: Thu, 9 Mar 2017 09:59:30 +0100
Subject: [PATCH] [4.0] logger: replace writer type with callbacks

Replaces switching between different writer types
with specific writer function callback:
service_writer_{socket,pipe,kmsg}
to be more easily extensible when adding new writers

Change-Id: I8552121bd50e20ca4872ed5e1536325a7acef279
---
 src/logger/logger.c | 62 +++++++++++++++++++++--------------------------------
 1 file changed, 25 insertions(+), 37 deletions(-)

diff --git a/src/logger/logger.c b/src/logger/logger.c
index 98543dc..5d6b779 100644
--- a/src/logger/logger.c
+++ b/src/logger/logger.c
@@ -111,17 +111,22 @@ enum entity_type {
 	ENTITY_SOCK_WRITE,
 };
 
-enum writer_state {
-	WRITER_SOCKET = 0,
-	WRITER_PIPE,
-	WRITER_KMSG
-};
-
 struct fd_entity {
 	int type;
 };
 
 struct writer;
+struct logger;
+
+/**
+ * @brief Service a writer
+ * @details Specific handler that event is delegated to, according to writers type
+ * @param[in] server The logger server
+ * @param[in] wr The writer who sent the request
+ * @param[in] event The relevant event
+ * @return 0 on success, else -errno
+ */
+typedef int (*service_writer_t)(struct logger* server, struct writer* wr, struct epoll_event* event);
 
 struct writer {
 	struct fd_entity   _entity;
@@ -134,13 +139,10 @@ struct writer {
 	struct log_buffer* buf_ptr;
 
 	int                readed;
-	char               state;
+	service_writer_t   service_writer;
 	char               buffer[LOG_MAX_SIZE];
 };
 
-struct reader;
-struct log_buffer;
-
 struct reader {
 	enum reader_type   type;
 	struct log_file    file;
@@ -153,6 +155,8 @@ struct reader {
 	char               partial_log[LOG_MAX_SIZE];
 };
 
+struct log_buffer;
+
 struct sock_data {
 	struct fd_entity   _entity;
 	int                fd;
@@ -215,6 +219,9 @@ struct logger_config_data {
 static struct file_buffer g_file_buffer;
 
 // function prototypes
+static int service_writer_socket(struct logger* server, struct writer* wr, struct epoll_event* event);
+static int service_writer_pipe(struct logger* server, struct writer* wr, struct epoll_event* event);
+static int service_writer_kmsg(struct logger* server, struct writer* wr, struct epoll_event* event);
 static void reader_free(struct reader* reader);
 static void logger_free(struct logger* l);
 static int parse_args(int argc, char ** argv, struct buffering * b);
@@ -446,6 +453,7 @@ static struct writer* writer_create(int fd, int rights)
 	if (w) {
 		w->working_fd = fd;
 		w->rights = rights;
+		w->service_writer = service_writer_socket;
 	}
 
 	return w;
@@ -469,7 +477,7 @@ static int create_kmsg_writer(struct logger * server)
 		return -errno;
 	}
 
-	w->state = WRITER_KMSG;
+	w->service_writer = service_writer_kmsg;
 	w->buf_ptr = server->buffers[LOG_ID_KMSG];
 
 	LIST_ADD(server->writers, w);
@@ -1306,7 +1314,7 @@ static int service_writer_handle_req_pipe(struct logger* server, struct writer*
 		goto err_remove;
 
 	writer_close_fd(server, wr);
-	wr->state = WRITER_PIPE;
+	wr->service_writer = service_writer_pipe;
 	wr->working_fd = pipe_fd[0];
 	wr->readed = 0;
 	return 0;
@@ -1450,28 +1458,6 @@ static int service_writer_kmsg(struct logger* server, struct writer* wr, struct
 }
 
 /**
- * @brief Service a writer
- * @details Relegates the event to specific handlers
- * @param[in] server The logger server
- * @param[in] wr The writer who sent the request
- * @param[in] event The relevant event
- * @return 0 on success, else -errno
- */
-static int service_writer(struct logger* server, struct writer* wr, struct epoll_event* event)
-{
-	switch (wr->state) {
-	case WRITER_SOCKET:
-		return service_writer_socket(server, wr, event);
-	case WRITER_PIPE:
-		return service_writer_pipe(server, wr, event);
-	case WRITER_KMSG:
-		return service_writer_kmsg(server, wr, event);
-	default:
-		return -EINVAL;
-	}
-}
-
-/**
  * @brief Service all readers
  * @details Update all readers with latest data
  * @param[in] server The logger server
@@ -1610,10 +1596,12 @@ static void dispatch_event(struct logger* server, struct fd_entity* entity, stru
 {
 	switch (entity->type) {
 	case ENTITY_WRITER: {
-		int r = service_writer(server, (struct writer*)entity, event);
+		struct writer *writer = (struct writer*)entity;
+		assert(writer->service_writer);
+		int r = writer->service_writer(server, writer, event);
 		if (r) {
-			LIST_REMOVE(server->writers, ((struct writer*)entity), writer);
-			writer_free((struct writer*)entity);
+			LIST_REMOVE(server->writers, writer, writer);
+			writer_free(writer);
 		}
 		break;
 	}
-- 
2.7.4