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c39c72ee PMF |
1 | /* Copyright (C) 2009 Pierre-Marc Fournier |
2 | * | |
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. | |
7 | * | |
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. | |
12 | * | |
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 | |
16 | */ | |
17 | ||
53107b8f PMF |
18 | #include <assert.h> |
19 | ||
b73a4c47 | 20 | #include "buffers.h" |
c93858f1 | 21 | #include "tracer.h" |
0b0cd937 | 22 | #include "ustd.h" |
6af64c43 | 23 | #include "usterr.h" |
0b0cd937 | 24 | |
d748a7de | 25 | /* This truncates to an offset in the buffer. */ |
0b0cd937 PMF |
26 | #define USTD_BUFFER_TRUNC(offset, bufinfo) \ |
27 | ((offset) & (~(((bufinfo)->subbuf_size*(bufinfo)->n_subbufs)-1))) | |
28 | ||
29 | void finish_consuming_dead_subbuffer(struct buffer_info *buf) | |
30 | { | |
b5b073e2 | 31 | struct ust_buffer *ustbuf = buf->bufstruct_mem; |
0b0cd937 | 32 | |
b5b073e2 PMF |
33 | long write_offset = local_read(&ustbuf->offset); |
34 | long consumed_offset = atomic_long_read(&ustbuf->consumed); | |
0b0cd937 PMF |
35 | |
36 | long i_subbuf; | |
37 | ||
38 | DBG("processing died buffer"); | |
39 | DBG("consumed offset is %ld", consumed_offset); | |
40 | DBG("write offset is %ld", write_offset); | |
41 | ||
d748a7de PMF |
42 | /* First subbuf that we need to consume now. It is not modulo'd. |
43 | * Consumed_offset is the next byte to consume. */ | |
53107b8f | 44 | long first_subbuf = consumed_offset / buf->subbuf_size; |
d748a7de PMF |
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; | |
0b0cd937 | 49 | |
211c34d2 PMF |
50 | DBG("first_subbuf=%ld", first_subbuf); |
51 | DBG("last_subbuf=%ld", last_subbuf); | |
d748a7de PMF |
52 | |
53 | if(last_subbuf - first_subbuf >= buf->n_subbufs) { | |
0b0cd937 PMF |
54 | DBG("an overflow has occurred, nothing can be recovered"); |
55 | return; | |
56 | } | |
57 | ||
d748a7de | 58 | /* Iterate on subbuffers to recover. */ |
0b0cd937 | 59 | for(i_subbuf=first_subbuf; ; i_subbuf++, i_subbuf %= buf->n_subbufs) { |
53107b8f | 60 | void *tmp; |
d748a7de PMF |
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. */ | |
b5b073e2 | 63 | long commit_seq = local_read(&ustbuf->commit_seq[i_subbuf]); |
0b0cd937 PMF |
64 | |
65 | unsigned long valid_length = buf->subbuf_size; | |
66 | long n_subbufs_order = get_count_order(buf->n_subbufs); | |
53107b8f PMF |
67 | long commit_seq_mask = (~0UL >> n_subbufs_order); |
68 | ||
d748a7de PMF |
69 | struct ltt_subbuffer_header *header = (struct ltt_subbuffer_header *)((char *)buf->mem+i_subbuf*buf->subbuf_size); |
70 | ||
71 | if((commit_seq & commit_seq_mask) == 0) { | |
72 | /* There is nothing to do. */ | |
73 | /* FIXME: is this needed? */ | |
53107b8f | 74 | break; |
d748a7de | 75 | } |
0b0cd937 | 76 | |
d748a7de PMF |
77 | /* Check if subbuf was fully written. This is from Mathieu's algorithm/paper. */ |
78 | if (((commit_seq - buf->subbuf_size) & commit_seq_mask) | |
0b0cd937 | 79 | - (USTD_BUFFER_TRUNC(consumed_offset, buf) >> n_subbufs_order) |
d748a7de | 80 | == 0) { |
8c36d1ee PMF |
81 | /* If it was, we only check the data_size. This is the amount of valid data at |
82 | * the beginning of the subbuffer. */ | |
83 | valid_length = header->data_size; | |
0b0cd937 | 84 | } |
53107b8f | 85 | else { |
8c36d1ee | 86 | /* If the subbuffer was not fully written, then we don't check data_size because |
d748a7de | 87 | * it hasn't been written yet. Instead we check commit_seq and use it to choose |
8c36d1ee | 88 | * a value for data_size. The viewer will need this value when parsing. |
d748a7de | 89 | */ |
53107b8f | 90 | |
d748a7de | 91 | valid_length = commit_seq & (buf->subbuf_size-1); |
8c36d1ee | 92 | header->data_size = valid_length; |
d748a7de | 93 | assert(i_subbuf == (last_subbuf % buf->n_subbufs)); |
53107b8f PMF |
94 | } |
95 | ||
d748a7de | 96 | |
53107b8f | 97 | patient_write(buf->file_fd, buf->mem + i_subbuf * buf->subbuf_size, valid_length); |
0b0cd937 | 98 | |
53107b8f PMF |
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); | |
103 | free(tmp); | |
0b0cd937 | 104 | |
d748a7de | 105 | if(i_subbuf == last_subbuf % buf->n_subbufs) |
0b0cd937 PMF |
106 | break; |
107 | } | |
108 | } | |
109 |