6295a8bc5a4391d6cd7b38b45c07dad66c1950c7
1 /* Copyright (C) 2009 Pierre-Marc Fournier
3 * This library is free software; you can redistribute it and/or
4 * modify it under the terms of the GNU Lesser General Public
5 * License as published by the Free Software Foundation; either
6 * version 2.1 of the License, or (at your option) any later version.
8 * This library is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * Lesser General Public License for more details.
13 * You should have received a copy of the GNU Lesser General Public
14 * License along with this library; if not, write to the Free Software
15 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
25 /* This truncates to an offset in the buffer. */
26 #define USTD_BUFFER_TRUNC(offset, bufinfo) \
27 ((offset) & (~(((bufinfo)->subbuf_size*(bufinfo)->n_subbufs)-1)))
29 void finish_consuming_dead_subbuffer(struct buffer_info
*buf
)
31 struct ust_buffer
*ustbuf
= buf
->bufstruct_mem
;
33 long write_offset
= local_read(&ustbuf
->offset
);
34 long consumed_offset
= atomic_long_read(&ustbuf
->consumed
);
38 DBG("processing died buffer");
39 DBG("consumed offset is %ld", consumed_offset
);
40 DBG("write offset is %ld", write_offset
);
42 /* First subbuf that we need to consume now. It is not modulo'd.
43 * Consumed_offset is the next byte to consume. */
44 long first_subbuf
= consumed_offset
/ buf
->subbuf_size
;
45 /* Last subbuf that we need to consume now. It is not modulo'd.
46 * Write_offset is the next place to write so write_offset-1 is the
47 * last place written. */
48 long last_subbuf
= (write_offset
- 1) / buf
->subbuf_size
;
50 DBG("first_subbuf=%ld", first_subbuf
);
51 DBG("last_subbuf=%ld", last_subbuf
);
53 if(last_subbuf
- first_subbuf
>= buf
->n_subbufs
) {
54 DBG("an overflow has occurred, nothing can be recovered");
58 /* Iterate on subbuffers to recover. */
59 for(i_subbuf
=first_subbuf
; ; i_subbuf
++, i_subbuf
%= buf
->n_subbufs
) {
61 /* commit_seq is the offset in the buffer of the end of the last sequential commit.
62 * Bytes beyond this limit cannot be recovered. This is a free-running counter. */
63 long commit_seq
= local_read(&ustbuf
->commit_seq
[i_subbuf
]);
65 unsigned long valid_length
= buf
->subbuf_size
;
66 long n_subbufs_order
= get_count_order(buf
->n_subbufs
);
67 long commit_seq_mask
= (~0UL >> n_subbufs_order
);
69 struct ltt_subbuffer_header
*header
= (struct ltt_subbuffer_header
*)((char *)buf
->mem
+i_subbuf
*buf
->subbuf_size
);
71 if((commit_seq
& commit_seq_mask
) == 0) {
72 /* There is nothing to do. */
73 /* FIXME: is this needed? */
77 /* Check if subbuf was fully written. This is from Mathieu's algorithm/paper. */
78 if (((commit_seq
- buf
->subbuf_size
) & commit_seq_mask
)
79 - (USTD_BUFFER_TRUNC(consumed_offset
, buf
) >> n_subbufs_order
)
81 /* If it was, we only check the lost_size. This is the lost padding at the end of
83 valid_length
= (unsigned long)buf
->subbuf_size
- header
->lost_size
;
86 /* If the subbuffer was not fully written, then we don't check lost_size because
87 * it hasn't been written yet. Instead we check commit_seq and use it to choose
88 * a value for lost_size. The viewer will need this value when parsing.
91 valid_length
= commit_seq
& (buf
->subbuf_size
-1);
92 header
->lost_size
= buf
->subbuf_size
-valid_length
;
93 assert(i_subbuf
== (last_subbuf
% buf
->n_subbufs
));
97 patient_write(buf
->file_fd
, buf
->mem
+ i_subbuf
* buf
->subbuf_size
, valid_length
);
99 /* pad with empty bytes */
100 tmp
= malloc(buf
->subbuf_size
-valid_length
);
101 memset(tmp
, 0, buf
->subbuf_size
-valid_length
);
102 patient_write(buf
->file_fd
, tmp
, buf
->subbuf_size
-valid_length
);
105 if(i_subbuf
== last_subbuf
% buf
->n_subbufs
)
This page took 0.043419 seconds and 4 git commands to generate.