+/* Copyright (C) 2009 Pierre-Marc Fournier
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <assert.h>
+
#include "tracer.h"
#include "ustd.h"
-#include "localerr.h"
+#include "usterr.h"
+/* This truncates to an offset in the buffer. */
#define USTD_BUFFER_TRUNC(offset, bufinfo) \
((offset) & (~(((bufinfo)->subbuf_size*(bufinfo)->n_subbufs)-1)))
void finish_consuming_dead_subbuffer(struct buffer_info *buf)
{
- struct ltt_channel_buf_struct *ltt_buf = buf->bufstruct_mem;
+ struct ust_buffer *ustbuf = buf->bufstruct_mem;
- long write_offset = local_read(<t_buf->offset);
- long consumed_offset = atomic_long_read(<t_buf->consumed);
+ long write_offset = local_read(&ustbuf->offset);
+ long consumed_offset = atomic_long_read(&ustbuf->consumed);
long i_subbuf;
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;
+ /* First subbuf that we need to consume now. It is not modulo'd.
+ * Consumed_offset is the next byte to consume. */
+ long first_subbuf = consumed_offset / buf->subbuf_size;
+ /* Last subbuf that we need to consume now. It is not modulo'd.
+ * Write_offset is the next place to write so write_offset-1 is the
+ * last place written. */
+ long last_subbuf = (write_offset - 1) / buf->subbuf_size;
+
+ DBG("first_subbuf=%ld", first_subbuf);
+ DBG("last_subbuf=%ld", last_subbuf);
- if(last_subbuf - first_subbuf > buf->n_subbufs) {
+ if(last_subbuf - first_subbuf >= buf->n_subbufs) {
DBG("an overflow has occurred, nothing can be recovered");
return;
}
+ /* Iterate on subbuffers to recover. */
for(i_subbuf=first_subbuf; ; i_subbuf++, i_subbuf %= buf->n_subbufs) {
- long commit_count = local_read(<t_buf->commit_count[i_subbuf]);
+ void *tmp;
+ /* commit_seq is the offset in the buffer of the end of the last sequential commit.
+ * Bytes beyond this limit cannot be recovered. This is a free-running counter. */
+ long commit_seq = local_read(&ustbuf->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);
- /* check if subbuf was fully written */
- if (((commit_count - buf->subbuf_size) & commit_count_mask)
+ struct ltt_subbuffer_header *header = (struct ltt_subbuffer_header *)((char *)buf->mem+i_subbuf*buf->subbuf_size);
+
+ if((commit_seq & commit_seq_mask) == 0) {
+ /* There is nothing to do. */
+ /* FIXME: is this needed? */
+ break;
+ }
+
+ /* Check if subbuf was fully written. This is from Mathieu's algorithm/paper. */
+ 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;
+ == 0) {
+ /* If it was, we only check the lost_size. This is the lost padding at the end of
+ * the subbuffer. */
+ valid_length = (unsigned long)buf->subbuf_size - header->lost_size;
+ }
+ else {
+ /* If the subbuffer was not fully written, then we don't check lost_size because
+ * it hasn't been written yet. Instead we check commit_seq and use it to choose
+ * a value for lost_size. The viewer will need this value when parsing.
+ */
+
+ valid_length = commit_seq & (buf->subbuf_size-1);
+ header->lost_size = buf->subbuf_size-valid_length;
+ assert(i_subbuf == (last_subbuf % buf->n_subbufs));
}
- patient_write(buf->file_fd, buf->mem + i_subbuf * buf->subbuf_size, buf->subbuf_size);
- if(i_subbuf == last_subbuf)
+ patient_write(buf->file_fd, buf->mem + i_subbuf * buf->subbuf_size, valid_length);
+
+ /* 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 % buf->n_subbufs)
break;
}
}
projects / ust.git / blobdiff