btr_add_output(): Fix memory leak in case node has no children.
[paraslash.git] / buffer_tree.c
1 #include <regex.h>
2 #include <stdbool.h>
3
4 #include "para.h"
5 #include "list.h"
6 #include "string.h"
7 #include "buffer_tree.h"
8 #include "error.h"
9
10
11 struct btr_buffer {
12 char *buf;
13 size_t size;
14 /** The number of references to this buffer. */
15 int refcount;
16 };
17
18 struct btr_buffer_reference {
19 struct btr_buffer *btrb;
20 size_t consumed;
21 /* Each buffer reference belongs to the buffer queue list of some buffer tree node. */
22 struct list_head node;
23 };
24
25 struct btr_node {
26 char *name;
27 struct btr_node *parent;
28 /* The position of this btr node in the buffer tree. */
29 struct list_head node;
30 /* The children nodes of this btr node are linked together in a list. */
31 struct list_head children;
32 /**
33 * The input queue is a list of references to btr buffers. Each item on
34 * the list represents an input buffer which has not been completely
35 * used by this btr node.
36 */
37 struct list_head input_queue;
38 btr_command_handler execute;
39 void *context;
40 };
41
42 #define FOR_EACH_CHILD(_tn, _btrn) list_for_each_entry((_tn), \
43 &((_btrn)->children), node)
44 #define FOR_EACH_CHILD_SAFE(_tn, _tmp, _btrn) \
45 list_for_each_entry_safe((_tn), (_tmp), &((_btrn)->children), node)
46
47 #define FOR_EACH_BUFFER_REF(_br, _btrn) \
48 list_for_each_entry((_br), &(_btrn)->input_queue, node)
49 #define FOR_EACH_BUFFER_REF_SAFE(_br, _tmp, _btrn) \
50 list_for_each_entry_safe((_br), (_tmp), &(_btrn)->input_queue, node)
51
52 struct btr_node *btr_new_node(const char *name, struct btr_node *parent,
53 btr_command_handler handler, void *context)
54 {
55 struct btr_node *btrn = para_malloc(sizeof(*btrn));
56
57 btrn->name = para_strdup(name);
58 btrn->parent = parent;
59 btrn->execute = handler;
60 btrn->context = context;
61 if (parent)
62 list_add_tail(&btrn->node, &parent->children);
63 INIT_LIST_HEAD(&btrn->children);
64 INIT_LIST_HEAD(&btrn->input_queue);
65 if (parent)
66 PARA_INFO_LOG("added %s as child of %s\n", name, parent->name);
67 else
68 PARA_INFO_LOG("added %s as btr root\n", name);
69 return btrn;
70 }
71
72 /*
73 * Allocate a new btr buffer.
74 *
75 * The freshly allocated buffer will have a zero refcount.
76 */
77 static struct btr_buffer *new_btrb(char *buf, size_t size)
78 {
79 struct btr_buffer *btrb = para_malloc(sizeof(*btrb));
80
81 btrb->buf = buf;
82 btrb->size = size;
83 btrb->refcount = 0;
84 return btrb;
85 }
86
87 /*
88 * Deallocate the reference, release the resources if refcount drops to zero.
89 */
90 static void btr_drop_buffer_reference(struct btr_buffer_reference *br)
91 {
92 struct btr_buffer *btrb = br->btrb;
93
94 //PARA_CRIT_LOG("dropping buffer reference %p\n", br);
95 list_del(&br->node);
96 free(br);
97 btrb->refcount--;
98 if (btrb->refcount == 0) {
99 free(btrb->buf);
100 free(btrb);
101 }
102 }
103
104 static void add_btrb_to_children(struct btr_buffer *btrb,
105 struct btr_node *btrn, size_t consumed)
106 {
107 struct btr_node *ch;
108
109 FOR_EACH_CHILD(ch, btrn) {
110 struct btr_buffer_reference *br = para_malloc(sizeof(*br));
111 br->btrb = btrb;
112 br->consumed = consumed;
113 list_add_tail(&br->node, &ch->input_queue);
114 btrb->refcount++;
115 }
116 }
117
118 void btr_add_output(char *buf, size_t size, struct btr_node *btrn)
119 {
120 struct btr_buffer *btrb;
121
122 assert(size != 0);
123 if (list_empty(&btrn->children)) {
124 free(buf);
125 return;
126 }
127 btrb = new_btrb(buf, size);
128 add_btrb_to_children(btrb, btrn, 0);
129 }
130
131 static void btr_pushdown_br(struct btr_buffer_reference *br, struct btr_node *btrn)
132 {
133 add_btrb_to_children(br->btrb, btrn, br->consumed);
134 btr_drop_buffer_reference(br);
135 }
136
137 void btr_pushdown(struct btr_node *btrn)
138 {
139 struct btr_buffer_reference *br, *tmp;
140
141 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
142 btr_pushdown_br(br, btrn);
143 }
144
145 int btr_pushdown_one(struct btr_node *btrn)
146 {
147 struct btr_buffer_reference *br;
148
149 if (list_empty(&btrn->input_queue))
150 return 0;
151 br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
152 btr_pushdown_br(br, btrn);
153 return 1;
154 }
155
156 /* Return true if this node has no children. */
157 bool btr_no_children(struct btr_node *btrn)
158 {
159 return list_empty(&btrn->children);
160 }
161
162 bool btr_no_parent(struct btr_node *btrn)
163 {
164 return !btrn->parent;
165 }
166
167 bool btr_inplace_ok(struct btr_node *btrn)
168 {
169 if (!btrn->parent)
170 return true;
171 return list_is_singular(&btrn->parent->children);
172 }
173
174 static inline size_t br_available_bytes(struct btr_buffer_reference *br)
175 {
176 return br->btrb->size - br->consumed;
177 }
178
179 size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf)
180 {
181 *buf = br->btrb->buf + br->consumed;
182 return br_available_bytes(br);
183 }
184
185 /**
186 * \return zero if the input buffer queue is empty.
187 */
188 size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
189 {
190 struct btr_buffer_reference *br;
191
192 if (list_empty(&btrn->input_queue)) {
193 *bufp = NULL;
194 return 0;
195 }
196 br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
197 return btr_get_buffer_by_reference(br, bufp);
198 }
199
200 void btr_consume(struct btr_node *btrn, size_t numbytes)
201 {
202 struct btr_buffer_reference *br;
203
204 assert(!list_empty(&btrn->input_queue));
205 br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
206 assert(br->consumed + numbytes <= br->btrb->size);
207 br->consumed += numbytes;
208 if (br->consumed == br->btrb->size)
209 btr_drop_buffer_reference(br);
210 }
211
212 static void flush_input_queue(struct btr_node *btrn)
213 {
214 struct btr_buffer_reference *br, *tmp;
215 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
216 btr_drop_buffer_reference(br);
217 }
218
219 void btr_del_node(struct btr_node *btrn)
220 {
221 struct btr_node *ch;
222
223 if (!btrn)
224 return;
225 PARA_NOTICE_LOG("deleting %s\n", btrn->name);
226 FOR_EACH_CHILD(ch, btrn)
227 ch->parent = NULL;
228 flush_input_queue(btrn);
229 if (btrn->parent)
230 list_del(&btrn->node);
231 free(btrn->name);
232 free(btrn);
233 }
234
235 size_t btr_get_input_queue_size(struct btr_node *btrn)
236 {
237 struct btr_buffer_reference *br;
238 size_t size = 0;
239
240 FOR_EACH_BUFFER_REF(br, btrn) {
241 //PARA_CRIT_LOG("size: %zu\n", size);
242 size += br_available_bytes(br);
243 }
244 return size;
245 }
246
247 void btr_splice_out_node(struct btr_node *btrn)
248 {
249 struct btr_node *ch, *tmp;
250
251 assert(btrn);
252 PARA_NOTICE_LOG("splicing out %s\n", btrn->name);
253 btr_pushdown(btrn);
254 if (btrn->parent)
255 list_del(&btrn->node);
256 FOR_EACH_CHILD_SAFE(ch, tmp, btrn) {
257 PARA_INFO_LOG("parent(%s): %s\n", ch->name,
258 btrn->parent? btrn->parent->name : "NULL");
259 ch->parent = btrn->parent;
260 if (btrn->parent)
261 list_move(&ch->node, &btrn->parent->children);
262 }
263 assert(list_empty(&btrn->children));
264 free(btrn->name);
265 free(btrn);
266 }
267
268 /**
269 * Return the size of the largest input queue.
270 *
271 * Iterates over all children of the given node.
272 */
273 size_t btr_bytes_pending(struct btr_node *btrn)
274 {
275 size_t max_size = 0;
276 struct btr_node *ch;
277
278 FOR_EACH_CHILD(ch, btrn) {
279 size_t size = btr_get_input_queue_size(ch);
280 max_size = PARA_MAX(max_size, size);
281 }
282 return max_size;
283 }
284
285 int btr_exec(struct btr_node *btrn, const char *command, char **value_result)
286 {
287 if (!btrn)
288 return -ERRNO_TO_PARA_ERROR(EINVAL);
289 if (!btrn->execute)
290 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
291 return btrn->execute(btrn, command, value_result);
292 }
293
294 int btr_exec_up(struct btr_node *btrn, const char *command, char **value_result)
295 {
296 int ret;
297
298 for (; btrn; btrn = btrn->parent) {
299 struct btr_node *parent = btrn->parent;
300 if (!parent)
301 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
302 if (!parent->execute)
303 continue;
304 PARA_INFO_LOG("parent: %s, cmd: %s\n", parent->name, command);
305 ret = parent->execute(parent, command, value_result);
306 if (ret == -ERRNO_TO_PARA_ERROR(ENOTSUP))
307 continue;
308 if (ret < 0)
309 return ret;
310 if (value_result && *value_result)
311 PARA_NOTICE_LOG("%s(%s): %s\n", command, parent->name,
312 *value_result);
313 return 1;
314 }
315 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
316 }
317
318 void *btr_context(struct btr_node *btrn)
319 {
320 return btrn->context;
321 }
322
323 /**
324 * Merge the first two input buffers into one.
325 *
326 * This is a quite expensive operation.
327 *
328 * \return The number of buffers that have been available (zero, one or two).
329 */
330 static int merge_input(struct btr_node *btrn)
331 {
332 struct btr_buffer_reference *brs[2], *br;
333 char *bufs[2], *buf;
334 size_t szs[2], sz;
335 int i;
336
337 if (list_empty(&btrn->input_queue))
338 return 0;
339 if (list_is_singular(&btrn->input_queue))
340 return 1;
341 i = 0;
342 /* get references to the first two buffers */
343 FOR_EACH_BUFFER_REF(br, btrn) {
344 brs[i] = br;
345 szs[i] = btr_get_buffer_by_reference(brs[i], bufs + i);
346 i++;
347 if (i == 2)
348 break;
349 }
350 /* make a new btrb that combines the two buffers and a br to it. */
351 sz = szs[0] + szs[1];
352 //PARA_CRIT_LOG("merging input buffers: (%zu, %zu) -> %zu\n",
353 // szs[0], szs[1], sz);
354 buf = para_malloc(sz);
355 /* TODO: Avoid this memcopy by introducing btr buffer pool. */
356 memcpy(buf, bufs[0], szs[0]);
357 memcpy(buf + szs[0], bufs[1], szs[1]);
358
359 br = para_malloc(sizeof(*br));
360 br->btrb = new_btrb(buf, sz);
361 br->btrb->refcount = 1;
362 br->consumed = 0;
363
364 /* replace the first two refs by the new one */
365 btr_drop_buffer_reference(brs[0]);
366 btr_drop_buffer_reference(brs[1]);
367 para_list_add(&br->node, &btrn->input_queue);
368 return 2;
369 }
370
371 void btr_merge(struct btr_node *btrn, size_t dest_size)
372 {
373 for (;;) {
374 char *buf;
375 size_t len = btr_next_buffer(btrn, &buf);
376 if (len >= dest_size)
377 return;
378 if (merge_input(btrn) < 2)
379 return;
380 }
381 }
382
383 bool btr_eof(struct btr_node *btrn)
384 {
385 char *buf;
386 size_t len = btr_next_buffer(btrn, &buf);
387
388 return (len == 0 && btr_no_parent(btrn));
389 }
390
391 void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth)
392 {
393 struct btr_node *ch;
394 const char spaces[] = " ", *space = spaces + 16 - depth;
395
396 if (depth > 16)
397 return;
398 para_log(loglevel, "%s%s\n", space, btrn->name);
399 FOR_EACH_CHILD(ch, btrn)
400 log_tree_recursively(ch, loglevel, depth + 1);
401 }
402
403 void btr_log_tree(struct btr_node *btrn, int loglevel)
404 {
405 return log_tree_recursively(btrn, loglevel, 0);
406 }