From b467de584912b8605c4190343e1b1ad0069e4cd3 Mon Sep 17 00:00:00 2001
From: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
Date: Tue, 18 Dec 2018 14:48:56 +0100
Subject: [PATCH] shell: Add dropping of expired messages

Log message get timestamp when being added to shell log message queue.
When adding to log message queue timeouts then all messages added
before timeout are dropped.

Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
---
 include/shell/shell_log_backend.h |  8 +++++-
 subsys/shell/shell_log_backend.c  | 47 +++++++++++++++++++++----------
 2 files changed, 39 insertions(+), 16 deletions(-)

diff --git a/include/shell/shell_log_backend.h b/include/shell/shell_log_backend.h
index 6be97d96a19..d1f5121a8b0 100644
--- a/include/shell/shell_log_backend.h
+++ b/include/shell/shell_log_backend.h
@@ -40,6 +40,12 @@ struct shell_log_backend {
 	u32_t timeout;
 };
 
+/** @brief Shell log backend message structure. */
+struct shell_log_backend_msg {
+	struct log_msg *msg;
+	u32_t timestamp;
+};
+
 /** @brief Prototype of function outputing processed data. */
 int shell_log_backend_output_func(u8_t *data, size_t length, void *ctx);
 
@@ -61,7 +67,7 @@ int shell_log_backend_output_func(u8_t *data, size_t length, void *ctx);
 #if CONFIG_LOG
 #define SHELL_LOG_BACKEND_DEFINE(_name, _buf, _size, _queue_size, _timeout)  \
 	LOG_BACKEND_DEFINE(_name##_backend, log_backend_shell_api, false);   \
-	K_MSGQ_DEFINE(_name##_msgq, sizeof(void *),			     \
+	K_MSGQ_DEFINE(_name##_msgq, sizeof(struct shell_log_backend_msg),    \
 			_queue_size, sizeof(void *));			     \
 	LOG_OUTPUT_DEFINE(_name##_log_output, shell_log_backend_output_func, \
 			  _buf, _size);					     \
diff --git a/subsys/shell/shell_log_backend.c b/subsys/shell/shell_log_backend.c
index 69ca0300572..bcb3d72edb9 100644
--- a/subsys/shell/shell_log_backend.c
+++ b/subsys/shell/shell_log_backend.c
@@ -26,12 +26,12 @@ void shell_log_backend_enable(const struct shell_log_backend *backend,
 
 static struct log_msg *msg_from_fifo(const struct shell_log_backend *backend)
 {
-	struct log_msg *msg;
+	struct shell_log_backend_msg msg;
 	int err;
 
 	err = k_msgq_get(backend->msgq, &msg, K_NO_WAIT);
 
-	return (err == 0) ? msg : NULL;
+	return (err == 0) ? msg.msg : NULL;
 }
 
 static void fifo_flush(const struct shell_log_backend *backend)
@@ -44,12 +44,40 @@ static void fifo_flush(const struct shell_log_backend *backend)
 	}
 }
 
+static void flush_expired_messages(const struct shell *shell)
+{
+	int err;
+	struct shell_log_backend_msg msg;
+	struct k_msgq *msgq = shell->log_backend->msgq;
+	u32_t timeout = shell->log_backend->timeout;
+	u32_t now = k_uptime_get_32();
+
+	while (1) {
+		err = k_msgq_peek(msgq, &msg);
+
+		if (err == 0 && ((now - msg.timestamp) > timeout)) {
+			(void)k_msgq_get(msgq, &msg, K_NO_WAIT);
+			log_msg_put(msg.msg);
+
+			if (IS_ENABLED(CONFIG_SHELL_STATS)) {
+				shell->stats->log_lost_cnt++;
+			}
+		} else {
+			break;
+		}
+	}
+}
+
 static void msg_to_fifo(const struct shell *shell,
 			struct log_msg *msg)
 {
 	int err;
+	struct shell_log_backend_msg t_msg = {
+		.msg = msg,
+		.timestamp = k_uptime_get_32()
+	};
 
-	err = k_msgq_put(shell->log_backend->msgq, &msg,
+	err = k_msgq_put(shell->log_backend->msgq, &t_msg,
 			 shell->log_backend->timeout);
 
 	switch (err) {
@@ -58,18 +86,7 @@ static void msg_to_fifo(const struct shell *shell,
 	case -EAGAIN:
 	case -ENOMSG:
 	{
-		struct log_msg *old_msg;
-
-		/* drop one message */
-		old_msg = msg_from_fifo(shell->log_backend);
-
-		if (old_msg) {
-			log_msg_put(old_msg);
-
-			if (IS_ENABLED(CONFIG_SHELL_STATS)) {
-				shell->stats->log_lost_cnt++;
-			}
-		}
+		flush_expired_messages(shell);
 
 		err = k_msgq_put(shell->log_backend->msgq, &msg, K_NO_WAIT);
 		if (err) {