From db21facb37a7c0d917e646a69a72f90a04d71e42 Mon Sep 17 00:00:00 2001
From: rusEfi <russianefi@gmail.com>
Date: Sun, 16 Nov 2014 18:03:30 -0600
Subject: [PATCH] auto-sync

---
 firmware/console_util/datalogging.c | 71 +++++++++++++++++++++--------
 1 file changed, 53 insertions(+), 18 deletions(-)

diff --git a/firmware/console_util/datalogging.c b/firmware/console_util/datalogging.c
index 59dcfe5daa..e9e6797bd6 100644
--- a/firmware/console_util/datalogging.c
+++ b/firmware/console_util/datalogging.c
@@ -46,16 +46,33 @@
 // we use this magic constant to make sure it's not just a random non-zero int in memory
 #define MAGIC_LOGGING_FLAG 45234441
 
+typedef char log_buf_t[DL_OUTPUT_BUFFER];
+
+/**
+ * we need to leave a byte for zero terminator, also two bytes for the \r\n in
+ * printWithLength, also couple of bytes just in case
+ */
+#define MAX_DL_CAPACITY (DL_OUTPUT_BUFFER - 5)
+
+static log_buf_t pendingBuffers0 CCM_OPTIONAL
+;
+static log_buf_t pendingBuffers1
+;
+
 /**
  * This is the buffer into which all the data providers write
  */
-static char pendingBuffer[DL_OUTPUT_BUFFER] CCM_OPTIONAL
-;
+static char *accumulationBuffer;
+
+/**
+ * amount of data accumulated so far
+ */
+static uint32_t accumulatedSize;
 
 /**
  * We copy all the pending data into this buffer once we are ready to push it out
  */
-static char outputBuffer[DL_OUTPUT_BUFFER];
+static char * outputBuffer;
 
 static MemoryStream intermediateLoggingBuffer;
 static uint8_t intermediateLoggingBufferData[INTERMEDIATE_LOGGING_BUFFER_SIZE] CCM_OPTIONAL
@@ -87,6 +104,9 @@ void append(Logging *logging, const char *text) {
 		return;
 	}
 	strcpy(logging->linePointer, text);
+    /**
+	 * And now we are pointing at the zero char at the end of the buffer again
+	 */
 	logging->linePointer += extraLen;
 }
 
@@ -313,6 +333,7 @@ void resetLogging(Logging *logging) {
 		return;
 	}
 	logging->linePointer = buffer;
+	logging->linePointer[0] = 0;
 }
 
 /**
@@ -363,25 +384,19 @@ void scheduleLogging(Logging *logging) {
 	int newLength = efiStrlen(logging->buffer);
 
 	bool alreadyLocked = lockOutputBuffer();
-	// I hope this is fast enough to operate under sys lock
-	int curLength = efiStrlen(pendingBuffer);
-	if (curLength + newLength >= DL_OUTPUT_BUFFER) {
+	if (accumulatedSize + newLength >= MAX_DL_CAPACITY) {
 		/**
 		 * if no one is consuming the data we have to drop it
-		 * this happens in case of serial-over-USB, todo: find a better solution
-		 *
+		 * this happens in case of serial-over-USB, todo: find a better solution?
 		 */
-//		strcpy(fatalMessage, "datalogging.c: output buffer overflow: ");
-//		strcat(fatalMessage, logging->name);
-//		fatal(fatalMessage);
 		if (!alreadyLocked) {
 			unlockOutputBuffer();
 		}
 		resetLogging(logging);
 		return;
 	}
-
-	strcat(pendingBuffer, logging->buffer);
+	strcpy(accumulationBuffer + accumulatedSize, logging->buffer);
+    accumulatedSize += newLength;
 	if (!alreadyLocked) {
 		unlockOutputBuffer();
 	}
@@ -393,21 +408,41 @@ uint32_t remainingSize(Logging *logging) {
 }
 
 /**
- * This method actually sends all the pending data to the communication layer
+ * This method actually sends all the pending data to the communication layer.
+ * This method is invoked by the main thread - that's the only thread which should be sending
+ * actual data to console in order to avoid concurrent access to serial hardware.
  */
 void printPending(void) {
 	lockOutputBuffer();
-	// we cannot output under syslock, so another buffer
-	strcpy(outputBuffer, pendingBuffer);
-	pendingBuffer[0] = 0; // reset pending buffer
+	/**
+	 * we cannot output under syslock, we simply rotate which buffer is which
+	 */
+	char *temp = outputBuffer;
+
+	int expectedOutputSize = accumulatedSize;
+	outputBuffer = accumulationBuffer;
+
+	accumulationBuffer = temp;
+	accumulatedSize = 0;
+	accumulationBuffer[0] = 0;
+
 	unlockOutputBuffer();
 
-	if (efiStrlen(outputBuffer) > 0) {
+	int actualOutputBuffer = efiStrlen(outputBuffer);
+	efiAssertVoid(actualOutputBuffer == expectedOutputSize, "out constr");
+
+	if (actualOutputBuffer > 0) {
 		printWithLength(outputBuffer);
 	}
 }
 
 void initIntermediateLoggingBuffer(void) {
+	pendingBuffers0[0] = 0;
+	pendingBuffers1[0] = 0;
+	accumulationBuffer = pendingBuffers0;
+	outputBuffer = pendingBuffers1;
+	accumulatedSize = 0;
+
 	msObjectInit(&intermediateLoggingBuffer, intermediateLoggingBufferData, INTERMEDIATE_LOGGING_BUFFER_SIZE, 0);
 	intermediateLoggingBufferInited = TRUE;
 }