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Make buildsystem use pkg-config to search for kcompat and liburcu
[lttng-ust.git]
/
ustd
/
lowlevel.c
diff --git
a/ustd/lowlevel.c
b/ustd/lowlevel.c
index 7c5dc3d99cdd47a1189009a9a35b7b624345e8ef..ff3875931a36c464c345c7c2a8823ee94e61f11d 100644
(file)
--- a/
ustd/lowlevel.c
+++ b/
ustd/lowlevel.c
@@
-4,6
+4,7
@@
#include "ustd.h"
#include "localerr.h"
#include "ustd.h"
#include "localerr.h"
+/* This truncates to an offset in the buffer. */
#define USTD_BUFFER_TRUNC(offset, bufinfo) \
((offset) & (~(((bufinfo)->subbuf_size*(bufinfo)->n_subbufs)-1)))
#define USTD_BUFFER_TRUNC(offset, bufinfo) \
((offset) & (~(((bufinfo)->subbuf_size*(bufinfo)->n_subbufs)-1)))
@@
-20,40
+21,61
@@
void finish_consuming_dead_subbuffer(struct buffer_info *buf)
DBG("consumed offset is %ld", consumed_offset);
DBG("write offset is %ld", write_offset);
DBG("consumed offset is %ld", consumed_offset);
DBG("write offset is %ld", write_offset);
+ /* 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;
long first_subbuf = consumed_offset / buf->subbuf_size;
- long last_subbuf = write_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;
- if(last_subbuf - first_subbuf > buf->n_subbufs) {
+ DBG("first_subbuf=%d", first_subbuf);
+ DBG("last_subbuf=%d", last_subbuf);
+
+ if(last_subbuf - first_subbuf >= buf->n_subbufs) {
DBG("an overflow has occurred, nothing can be recovered");
return;
}
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) {
void *tmp;
for(i_subbuf=first_subbuf; ; i_subbuf++, i_subbuf %= buf->n_subbufs) {
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(<t_buf->commit_seq[i_subbuf]);
unsigned long valid_length = buf->subbuf_size;
long n_subbufs_order = get_count_order(buf->n_subbufs);
long commit_seq_mask = (~0UL >> n_subbufs_order);
long commit_seq = local_read(<t_buf->commit_seq[i_subbuf]);
unsigned long valid_length = buf->subbuf_size;
long n_subbufs_order = get_count_order(buf->n_subbufs);
long commit_seq_mask = (~0UL >> n_subbufs_order);
- if((commit_seq & commit_seq_mask) == 0)
+ 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;
break;
+ }
- /*
check if subbuf was fully written
*/
- if (
!
((commit_seq - buf->subbuf_size) & commit_seq_mask)
+ /*
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)
- (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;
+ == 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 {
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;
+ /* 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;
+ valid_length = commit_seq
& (buf->subbuf_size-1)
;
header->lost_size = buf->subbuf_size-valid_length;
header->lost_size = buf->subbuf_size-valid_length;
- assert(i_subbuf ==
last_subbuf
);
+ assert(i_subbuf ==
(last_subbuf % buf->n_subbufs)
);
}
}
+
patient_write(buf->file_fd, buf->mem + i_subbuf * buf->subbuf_size, valid_length);
/* pad with empty bytes */
patient_write(buf->file_fd, buf->mem + i_subbuf * buf->subbuf_size, valid_length);
/* pad with empty bytes */
@@
-62,7
+84,7
@@
void finish_consuming_dead_subbuffer(struct buffer_info *buf)
patient_write(buf->file_fd, tmp, buf->subbuf_size-valid_length);
free(tmp);
patient_write(buf->file_fd, tmp, buf->subbuf_size-valid_length);
free(tmp);
- if(i_subbuf == last_subbuf)
+ if(i_subbuf == last_subbuf
% buf->n_subbufs
)
break;
}
}
break;
}
}
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