Introduce "--blocking-timeout" channel parameter
[lttng-tools.git] / src / common / dynamic-buffer.c
1 /*
2 * Copyright (C) 2017 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU Lesser General Public License, version 2.1 only,
6 * as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
11 * for more details.
12 *
13 * You should have received a copy of the GNU Lesser General Public License
14 * along with this program; if not, write to the Free Software Foundation,
15 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
16 */
17
18 #include <common/dynamic-buffer.h>
19 #include <common/macros.h>
20 #include <common/utils.h>
21 #include <assert.h>
22
23 /*
24 * Round to (upper) power of two, val is returned if it already is a power of
25 * two.
26 */
27 static
28 size_t round_to_power_of_2(size_t val)
29 {
30 int order;
31 size_t rounded;
32
33 order = utils_get_count_order_u64(val);
34 assert(order >= 0);
35 rounded = (1ULL << order);
36 assert(rounded >= val);
37
38 return rounded;
39 }
40
41 void lttng_dynamic_buffer_init(struct lttng_dynamic_buffer *buffer)
42 {
43 assert(buffer);
44 memset(buffer, 0, sizeof(*buffer));
45 }
46
47 int lttng_dynamic_buffer_append(struct lttng_dynamic_buffer *buffer,
48 const void *buf, size_t len)
49 {
50 int ret = 0;
51
52 if (!buffer || (!buf && len)) {
53 ret = -1;
54 goto end;
55 }
56
57 if (len == 0) {
58 /* Not an error, no-op. */
59 goto end;
60 }
61
62 assert(buffer->_capacity >= buffer->size);
63 if (buffer->_capacity < (len + buffer->size)) {
64 ret = lttng_dynamic_buffer_set_capacity(buffer,
65 buffer->_capacity +
66 (len - (buffer->_capacity - buffer->size)));
67 if (ret) {
68 goto end;
69 }
70 }
71
72 memcpy(buffer->data + buffer->size, buf, len);
73 buffer->size += len;
74 end:
75 return ret;
76 }
77
78 int lttng_dynamic_buffer_append_buffer(struct lttng_dynamic_buffer *dst_buffer,
79 struct lttng_dynamic_buffer *src_buffer)
80 {
81 int ret;
82
83 if (!dst_buffer || !src_buffer) {
84 ret = -1;
85 goto end;
86 }
87
88 ret = lttng_dynamic_buffer_append(dst_buffer, src_buffer->data,
89 src_buffer->size);
90 end:
91 return ret;
92 }
93
94 int lttng_dynamic_buffer_set_size(struct lttng_dynamic_buffer *buffer,
95 size_t new_size)
96 {
97 int ret = 0;
98
99 if (!buffer) {
100 goto end;
101 }
102
103 if (new_size == buffer->size) {
104 goto end;
105 }
106
107 if (new_size > buffer->_capacity) {
108 size_t original_size = buffer->size;
109 size_t original_capacity = buffer->_capacity;
110
111 ret = lttng_dynamic_buffer_set_capacity(buffer, new_size);
112 if (ret) {
113 goto end;
114 }
115
116 /*
117 * Zero-initialize the space that was left in the buffer at the
118 * before we increased its capacity (original capacity - original size).
119 * The newly acquired capacity (new capacity - original capacity)
120 * is zeroed by lttng_dynamic_buffer_set_capacity().
121 */
122 memset(buffer->data + original_size, 0,
123 original_capacity - original_size);
124 } else if (new_size > buffer->size) {
125 memset(buffer->data + buffer->size, 0, new_size - buffer->size);
126 } else {
127 /*
128 * Shrinking size. There is no need to zero-out the newly
129 * released memory as it will either be:
130 * - overwritten by lttng_dynamic_buffer_append,
131 * - expanded later, which will zero-out the memory
132 *
133 * Users of external APIs are encouraged to set the buffer's
134 * size _before_ making such calls.
135 */
136 }
137 buffer->size = new_size;
138 end:
139 return ret;
140 }
141
142 int lttng_dynamic_buffer_set_capacity(struct lttng_dynamic_buffer *buffer,
143 size_t demanded_capacity)
144 {
145 int ret = 0;
146 void *new_buf;
147 size_t new_capacity = round_to_power_of_2(demanded_capacity);
148
149 if (!buffer || demanded_capacity < buffer->size) {
150 /*
151 * Shrinking a buffer's size by changing its capacity is
152 * unsupported.
153 */
154 ret = -1;
155 goto end;
156 }
157
158 if (new_capacity == buffer->_capacity) {
159 goto end;
160 }
161
162 /* Memory is initialized by the size increases. */
163 new_buf = realloc(buffer->data, new_capacity);
164 if (!new_buf) {
165 ret = -1;
166 goto end;
167 }
168 buffer->data = new_buf;
169 buffer->_capacity = new_capacity;
170 end:
171 return ret;
172 }
173
174 /* Release any memory used by the dynamic buffer. */
175 void lttng_dynamic_buffer_reset(struct lttng_dynamic_buffer *buffer)
176 {
177 if (!buffer) {
178 return;
179 }
180 buffer->size = 0;
181 buffer->_capacity = 0;
182 free(buffer->data);
183 }
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