1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
/* Ringbuffer implementation, tailored for logging.
* This is a lossy ringbuffer. It keeps up to N of the newest messages,
* overwriting the oldest as newer ones come in.
*
* (C) 2012-2013, Katerina Barone-Adesi <kat.obsc@gmail.com>
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
/*! \file strrb.c
* \brief Lossy string ringbuffer for logging; keeps newest messages.
*/
#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <osmocom/core/strrb.h>
/* Ringbuffer assumptions, invarients, and notes:
* - start is the index of the first used index slot in the ring buffer.
* - end is the index of the next index slot in the ring buffer.
* - start == end => buffer is empty
* - Consequence: the buffer can hold at most size - 1 messages
* (if this were not the case, full and empty buffers would be indistinguishable
* given the conventions in this implementation).
* - Whenever the ringbuffer is full, start is advanced. The second oldest
* message becomes unreachable by valid indexes (end is not a valid index)
* and the oldest message is overwritten (if there was a message there, which
* is the case unless this is the first time the ringbuffer becomes full).
*/
/*! \brief Create an empty, initialized osmo_strrb.
* \param[in] ctx The talloc memory context which should own this.
* \param[in] rb_size The number of message slots the osmo_strrb can hold.
* \returns A struct osmo_strrb* on success, NULL in case of error.
*
* This function creates and initializes a ringbuffer.
* Note that the ringbuffer stores at most rb_size - 1 messages.
*/
struct osmo_strrb *osmo_strrb_create(TALLOC_CTX * ctx, size_t rb_size)
{
struct osmo_strrb *rb = NULL;
unsigned int i;
rb = talloc_zero(ctx, struct osmo_strrb);
if (!rb)
goto alloc_error;
/* start and end are zero already, which is correct */
rb->size = rb_size;
rb->buffer = talloc_array(rb, char *, rb->size);
if (!rb->buffer)
goto alloc_error;
for (i = 0; i < rb->size; i++) {
rb->buffer[i] =
talloc_zero_size(rb->buffer, RB_MAX_MESSAGE_SIZE);
if (!rb->buffer[i])
goto alloc_error;
}
return rb;
alloc_error: /* talloc_free(NULL) is safe */
talloc_free(rb);
return NULL;
}
/*! \brief Check if an osmo_strrb is empty.
* \param[in] rb The osmo_strrb to check.
* \returns True if the osmo_strrb is empty, false otherwise.
*/
bool osmo_strrb_is_empty(const struct osmo_strrb *rb)
{
return rb->end == rb->start;
}
/*! \brief Return a pointer to the Nth string in the osmo_strrb.
* \param[in] rb The osmo_strrb to search.
* \param[in] string_index The index sought (N), zero-indexed.
*
* Return a pointer to the Nth string in the osmo_strrb.
* Return NULL if there is no Nth string.
* Note that N is zero-indexed.
* \returns A pointer to the target string on success, NULL in case of error.
*/
const char *osmo_strrb_get_nth(const struct osmo_strrb *rb,
unsigned int string_index)
{
unsigned int offset = string_index + rb->start;
if ((offset >= rb->size) && (rb->start > rb->end))
offset -= rb->size;
if (_osmo_strrb_is_bufindex_valid(rb, offset))
return rb->buffer[offset];
return NULL;
}
bool _osmo_strrb_is_bufindex_valid(const struct osmo_strrb *rb,
unsigned int bufi)
{
if (osmo_strrb_is_empty(rb))
return 0;
if (bufi >= rb->size)
return 0;
if (rb->start < rb->end)
return (bufi >= rb->start) && (bufi < rb->end);
return (bufi < rb->end) || (bufi >= rb->start);
}
/*! \brief Count the number of log messages in an osmo_strrb.
* \param[in] rb The osmo_strrb to count the elements of.
*
* \returns The number of log messages in the osmo_strrb.
*/
size_t osmo_strrb_elements(const struct osmo_strrb *rb)
{
if (rb->end < rb->start)
return rb->end + (rb->size - rb->start);
return rb->end - rb->start;
}
/*! \brief Add a string to the osmo_strrb.
* \param[in] rb The osmo_strrb to add to.
* \param[in] data The string to add.
*
* Add a message to the osmo_strrb.
* Older messages will be overwritten as necessary.
* \returns 0 normally, 1 as a warning (ie, if data was truncated).
*/
int osmo_strrb_add(struct osmo_strrb *rb, const char *data)
{
size_t len = strlen(data);
int ret = 0;
if (len >= RB_MAX_MESSAGE_SIZE) {
len = RB_MAX_MESSAGE_SIZE - 1;
ret = 1;
}
memcpy(rb->buffer[rb->end], data, len);
rb->buffer[rb->end][len] = '\0';
rb->end += 1;
rb->end %= rb->size;
/* The buffer is full; oldest message is forgotten - see notes above */
if (rb->end == rb->start) {
rb->start += 1;
rb->start %= rb->size;
}
return ret;
}
|
