From: Pierre-Marc Fournier <pierre-marc.fournier@polymtl.ca>
Date: Tue, 7 Apr 2009 01:00:50 +0000 (-0400)
Subject: ustd: use commit_seq to get buffers from crashed process
X-Git-Tag: v1.9.1~1010
X-Git-Url: http://git.lttng.org./?a=commitdiff_plain;h=53107b8f0fcc8f46a12f926b37a6a87eeccac887;p=lttng-ust.git

ustd: use commit_seq to get buffers from crashed process

it works!
---

diff --git a/ustd/lowlevel.c b/ustd/lowlevel.c
index f386089e..7c5dc3d9 100644
--- a/ustd/lowlevel.c
+++ b/ustd/lowlevel.c
@@ -1,3 +1,5 @@
+#include <assert.h>
+
 #include "tracer.h"
 #include "ustd.h"
 #include "localerr.h"
@@ -18,8 +20,8 @@ void finish_consuming_dead_subbuffer(struct buffer_info *buf)
 	DBG("consumed offset is %ld", consumed_offset);
 	DBG("write offset is %ld", write_offset);
 
-	long first_subbuf = write_offset / buf->subbuf_size;
-	long last_subbuf = consumed_offset / buf->subbuf_size;
+	long first_subbuf = consumed_offset / buf->subbuf_size;
+	long last_subbuf = write_offset / buf->subbuf_size;
 
 	if(last_subbuf - first_subbuf > buf->n_subbufs) {
 		DBG("an overflow has occurred, nothing can be recovered");
@@ -27,21 +29,38 @@ void finish_consuming_dead_subbuffer(struct buffer_info *buf)
 	}
 
 	for(i_subbuf=first_subbuf; ; i_subbuf++, i_subbuf %= buf->n_subbufs) {
-		long commit_count = local_read(&ltt_buf->commit_count[i_subbuf]);
+		void *tmp;
+		long commit_seq = local_read(&ltt_buf->commit_seq[i_subbuf]);
 
 		unsigned long valid_length = buf->subbuf_size;
 		long n_subbufs_order = get_count_order(buf->n_subbufs);
-		long commit_count_mask = (~0UL >> n_subbufs_order);
+		long commit_seq_mask = (~0UL >> n_subbufs_order);
+
+		if((commit_seq & commit_seq_mask) == 0)
+			break;
 
 		/* check if subbuf was fully written */
-		if (((commit_count - buf->subbuf_size) & commit_count_mask)
+		if (!((commit_seq - buf->subbuf_size) & commit_seq_mask)
 		    - (USTD_BUFFER_TRUNC(consumed_offset, buf) >> n_subbufs_order)
 		    != 0) {
 			struct ltt_subbuffer_header *header = (struct ltt_subbuffer_header *)((char *)buf->mem)+i_subbuf*buf->subbuf_size;
-			valid_length = buf->subbuf_size - header->lost_size;
+			valid_length = (unsigned long)buf->subbuf_size - header->lost_size;
 		}
+		else {
+			struct ltt_subbuffer_header *header = (struct ltt_subbuffer_header *)((char *)buf->mem)+i_subbuf*buf->subbuf_size;
+
+			valid_length = commit_seq;
+			header->lost_size = buf->subbuf_size-valid_length;
+			assert(i_subbuf == last_subbuf);
+		}
+
+		patient_write(buf->file_fd, buf->mem + i_subbuf * buf->subbuf_size, valid_length);
 
-		patient_write(buf->file_fd, buf->mem + i_subbuf * buf->subbuf_size, buf->subbuf_size);
+		/* pad with empty bytes */
+		tmp = malloc(buf->subbuf_size-valid_length);
+		memset(tmp, 0, buf->subbuf_size-valid_length);
+		patient_write(buf->file_fd, tmp, buf->subbuf_size-valid_length);
+		free(tmp);
 
 		if(i_subbuf == last_subbuf)
 			break;