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_free_node(struct btr_node *btrn)
 220 {
 221         if (!btrn)
 222                 return;
 223         free(btrn->name);
 224         free(btrn);
 225 }
 226
 227 void btr_remove_node(struct btr_node *btrn)
 228 {
 229         struct btr_node *ch;
 230
 231         if (!btrn)
 232                 return;
 233         PARA_NOTICE_LOG("removing btr node %s from buffer tree\n", btrn->name);
 234         FOR_EACH_CHILD(ch, btrn)
 235                 ch->parent = NULL;
 236         flush_input_queue(btrn);
 237         if (btrn->parent)
 238                 list_del(&btrn->node);
 239 }
 240
 241 size_t btr_get_input_queue_size(struct btr_node *btrn)
 242 {
 243         struct btr_buffer_reference *br;
 244         size_t size = 0;
 245
 246         FOR_EACH_BUFFER_REF(br, btrn) {
 247                 //PARA_CRIT_LOG("size: %zu\n", size);
 248                 size += br_available_bytes(br);
 249         }
 250         return size;
 251 }
 252
 253 void btr_splice_out_node(struct btr_node *btrn)
 254 {
 255         struct btr_node *ch, *tmp;
 256
 257         assert(btrn);
 258         PARA_NOTICE_LOG("splicing out %s\n", btrn->name);
 259         btr_pushdown(btrn);
 260         if (btrn->parent)
 261                 list_del(&btrn->node);
 262         FOR_EACH_CHILD_SAFE(ch, tmp, btrn) {
 263                 PARA_INFO_LOG("parent(%s): %s\n", ch->name,
 264                         btrn->parent? btrn->parent->name : "NULL");
 265                 ch->parent = btrn->parent;
 266                 if (btrn->parent)
 267                         list_move(&ch->node, &btrn->parent->children);
 268         }
 269         assert(list_empty(&btrn->children));
 270 }
 271
 272 /**
 273  * Return the size of the largest input queue.
 274  *
 275  * Iterates over all children of the given node.
 276  */
 277 size_t btr_bytes_pending(struct btr_node *btrn)
 278 {
 279         size_t max_size = 0;
 280         struct btr_node *ch;
 281
 282         FOR_EACH_CHILD(ch, btrn) {
 283                 size_t size = btr_get_input_queue_size(ch);
 284                 max_size = PARA_MAX(max_size, size);
 285         }
 286         return max_size;
 287 }
 288
 289 int btr_exec(struct btr_node *btrn, const char *command, char **value_result)
 290 {
 291         if (!btrn)
 292                 return -ERRNO_TO_PARA_ERROR(EINVAL);
 293         if (!btrn->execute)
 294                 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
 295         return btrn->execute(btrn, command, value_result);
 296 }
 297
 298 int btr_exec_up(struct btr_node *btrn, const char *command, char **value_result)
 299 {
 300         int ret;
 301
 302         for (; btrn; btrn = btrn->parent) {
 303                 struct btr_node *parent = btrn->parent;
 304                 if (!parent)
 305                         return -ERRNO_TO_PARA_ERROR(ENOTSUP);
 306                 if (!parent->execute)
 307                         continue;
 308                 PARA_INFO_LOG("parent: %s, cmd: %s\n", parent->name, command);
 309                 ret = parent->execute(parent, command, value_result);
 310                 if (ret == -ERRNO_TO_PARA_ERROR(ENOTSUP))
 311                         continue;
 312                 if (ret < 0)
 313                         return ret;
 314                 if (value_result && *value_result)
 315                         PARA_NOTICE_LOG("%s(%s): %s\n", command, parent->name,
 316                                 *value_result);
 317                 return 1;
 318         }
 319         return -ERRNO_TO_PARA_ERROR(ENOTSUP);
 320 }
 321
 322 void *btr_context(struct btr_node *btrn)
 323 {
 324         return btrn->context;
 325 }
 326
 327 /**
 328  * Merge the first two input buffers into one.
 329  *
 330  * This is a quite expensive operation.
 331  *
 332  * \return The number of buffers that have been available (zero, one or two).
 333  */
 334 static int merge_input(struct btr_node *btrn)
 335 {
 336         struct btr_buffer_reference *brs[2], *br;
 337         char *bufs[2], *buf;
 338         size_t szs[2], sz;
 339         int i;
 340
 341         if (list_empty(&btrn->input_queue))
 342                 return 0;
 343         if (list_is_singular(&btrn->input_queue))
 344                 return 1;
 345         i = 0;
 346         /* get references to the first two buffers */
 347         FOR_EACH_BUFFER_REF(br, btrn) {
 348                 brs[i] = br;
 349                 szs[i] = btr_get_buffer_by_reference(brs[i], bufs + i);
 350                 i++;
 351                 if (i == 2)
 352                         break;
 353         }
 354         /* make a new btrb that combines the two buffers and a br to it. */
 355         sz = szs[0] + szs[1];
 356         //PARA_CRIT_LOG("merging input buffers: (%zu, %zu) -> %zu\n",
 357         //      szs[0], szs[1], sz);
 358         buf = para_malloc(sz);
 359         /* TODO: Avoid this memcopy by introducing btr buffer pool. */
 360         memcpy(buf, bufs[0], szs[0]);
 361         memcpy(buf + szs[0], bufs[1], szs[1]);
 362
 363         br = para_malloc(sizeof(*br));
 364         br->btrb = new_btrb(buf, sz);
 365         br->btrb->refcount = 1;
 366         br->consumed = 0;
 367
 368         /* replace the first two refs by the new one */
 369         btr_drop_buffer_reference(brs[0]);
 370         btr_drop_buffer_reference(brs[1]);
 371         para_list_add(&br->node, &btrn->input_queue);
 372         return 2;
 373 }
 374
 375 void btr_merge(struct btr_node *btrn, size_t dest_size)
 376 {
 377         for (;;) {
 378                 char *buf;
 379                 size_t len = btr_next_buffer(btrn, &buf);
 380                 if (len >= dest_size)
 381                         return;
 382                 if (merge_input(btrn) < 2)
 383                         return;
 384         }
 385 }
 386
 387 bool btr_eof(struct btr_node *btrn)
 388 {
 389         char *buf;
 390         size_t len = btr_next_buffer(btrn, &buf);
 391
 392         return (len == 0 && btr_no_parent(btrn));
 393 }
 394
 395 void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth)
 396 {
 397         struct btr_node *ch;
 398         const char spaces[] = "                 ", *space = spaces + 16 - depth;
 399
 400         if (depth > 16)
 401                 return;
 402         para_log(loglevel, "%s%s\n", space, btrn->name);
 403         FOR_EACH_CHILD(ch, btrn)
 404                 log_tree_recursively(ch, loglevel, depth + 1);
 405 }
 406
 407 void btr_log_tree(struct btr_node *btrn, int loglevel)
 408 {
 409         return log_tree_recursively(btrn, loglevel, 0);
 410 }
 411
 412 /** 640K ought to be enough for everybody ;) */
 413 #define BTRN_MAX_PENDING (640 * 1024)
 414
 415 int btr_node_status(struct btr_node *btrn, size_t min_iqs)
 416 {
 417         size_t iqs;
 418
 419         if (btr_eof(btrn))
 420                 return -E_BTR_EOF;
 421         if (btr_bytes_pending(btrn) > BTRN_MAX_PENDING)
 422                 return 0;
 423         iqs = btr_get_input_queue_size(btrn);
 424         if (iqs == 0) /* we have a parent, because not eof */
 425                 return 0;
 426         if (iqs < min_iqs && !btr_no_parent(btrn))
 427                 return 0;
 428         return 1;
 429 }