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
  45 #define FOR_EACH_BUFFER_REF(_br, _btrn) \
  46         list_for_each_entry((_br), &(_btrn)->input_queue, node)
  47 #define FOR_EACH_BUFFER_REF_SAFE(_br, _tmp, _btrn) \
  48         list_for_each_entry_safe((_br), (_tmp), &(_btrn)->input_queue, node)
  49
  50 struct btr_node *btr_new_node(char *name, struct btr_node *parent,
  51                 btr_command_handler handler, void *context)
  52 {
  53         struct btr_node *btrn = para_malloc(sizeof(*btrn));
  54
  55         btrn->name = para_strdup(name);
  56         btrn->parent = parent;
  57         btrn->execute = handler;
  58         btrn->context = context;
  59         if (parent)
  60                 list_add_tail(&btrn->node, &parent->children);
  61         INIT_LIST_HEAD(&btrn->children);
  62         INIT_LIST_HEAD(&btrn->input_queue);
  63         return btrn;
  64 }
  65
  66 /*
  67  * Allocate a new btr buffer.
  68  *
  69  * The freshly allocated buffer will have a zero refcount.
  70  */
  71 static struct btr_buffer *new_btrb(char *buf, size_t size)
  72 {
  73         struct btr_buffer *btrb = para_malloc(sizeof(*btrb));
  74
  75         btrb->buf = buf;
  76         btrb->size = size;
  77         btrb->refcount = 0;
  78         return btrb;
  79 }
  80
  81 /*
  82  * Deallocate the reference, release the resources if refcount drops to zero.
  83  */
  84 static void btr_drop_buffer_reference(struct btr_buffer_reference *br)
  85 {
  86         struct btr_buffer *btrb = br->btrb;
  87
  88         //PARA_CRIT_LOG("dropping buffer reference %p\n", br);
  89         list_del(&br->node);
  90         free(br);
  91         btrb->refcount--;
  92         if (btrb->refcount == 0) {
  93                 free(btrb->buf);
  94                 free(btrb);
  95         }
  96 }
  97
  98 static void add_btrb_to_children(struct btr_buffer *btrb,
  99                 struct btr_node *btrn, size_t consumed)
 100 {
 101         struct btr_node *ch;
 102
 103         FOR_EACH_CHILD(ch, btrn) {
 104                 struct btr_buffer_reference *br = para_malloc(sizeof(*br));
 105                 br->btrb = btrb;
 106                 br->consumed = consumed;
 107                 list_add_tail(&br->node, &ch->input_queue);
 108                 btrb->refcount++;
 109         }
 110 }
 111
 112 void btr_add_output(char *buf, size_t size, struct btr_node *btrn)
 113 {
 114         struct btr_buffer *btrb;
 115
 116         btrb = new_btrb(buf, size);
 117         add_btrb_to_children(btrb, btrn, 0);
 118 }
 119
 120 static void btr_pushdown_br(struct btr_buffer_reference *br, struct btr_node *btrn)
 121 {
 122         add_btrb_to_children(br->btrb, btrn, br->consumed);
 123         btr_drop_buffer_reference(br);
 124 }
 125
 126 void btr_pushdown(struct btr_node *btrn)
 127 {
 128         struct btr_buffer_reference *br, *tmp;
 129
 130         FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
 131                 btr_pushdown_br(br, btrn);
 132 }
 133
 134 /* Return true if this node has no children. */
 135 bool btr_no_children(struct btr_node *btrn)
 136 {
 137         return list_empty(&btrn->children);
 138 }
 139
 140 bool btr_no_parent(struct btr_node *btrn)
 141 {
 142         return !btrn->parent;
 143 }
 144
 145 bool btr_inplace_ok(struct btr_node *btrn)
 146 {
 147         if (!btrn->parent)
 148                 return true;
 149         return list_is_singular(&btrn->parent->children);
 150 }
 151
 152 static inline size_t br_available_bytes(struct btr_buffer_reference *br)
 153 {
 154         return br->btrb->size - br->consumed;
 155 }
 156
 157 size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf)
 158 {
 159         *buf = br->btrb->buf + br->consumed;
 160         return br_available_bytes(br);
 161 }
 162
 163 size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
 164 {
 165         struct btr_buffer_reference *br;
 166
 167         if (list_empty(&btrn->input_queue)) {
 168                 *bufp = NULL;
 169                 return 0;
 170         }
 171         br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
 172         return btr_get_buffer_by_reference(br, bufp);
 173 }
 174
 175 void btr_consume(struct btr_node *btrn, size_t numbytes)
 176 {
 177         struct btr_buffer_reference *br;
 178
 179         assert(!list_empty(&btrn->input_queue));
 180         br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
 181         assert(br->consumed + numbytes <= br->btrb->size);
 182         br->consumed += numbytes;
 183         if (br->consumed == br->btrb->size)
 184                 btr_drop_buffer_reference(br);
 185 }
 186
 187 static void flush_input_queue(struct btr_node *btrn)
 188 {
 189         struct btr_buffer_reference *br, *tmp;
 190         FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
 191                 btr_drop_buffer_reference(br);
 192 }
 193
 194 void btr_del_node(struct btr_node *btrn)
 195 {
 196         struct btr_node *ch;
 197
 198         if (!btrn)
 199                 return;
 200         PARA_NOTICE_LOG("deleting %s\n", btrn->name);
 201         FOR_EACH_CHILD(ch, btrn)
 202                 ch->parent = NULL;
 203         flush_input_queue(btrn);
 204         if (btrn->parent)
 205                 list_del(&btrn->node);
 206         free(btrn->name);
 207         free(btrn);
 208 }
 209
 210 size_t btr_get_input_queue_size(struct btr_node *btrn)
 211 {
 212         struct btr_buffer_reference *br;
 213         size_t size = 0;
 214
 215         FOR_EACH_BUFFER_REF(br, btrn) {
 216                 //PARA_CRIT_LOG("size: %zu\n", size);
 217                 size += br_available_bytes(br);
 218         }
 219         return size;
 220 }
 221
 222 int btr_splice_out_node(struct btr_node *btrn)
 223 {
 224         struct btr_node *ch;
 225
 226         if (!btrn)
 227                 return -ERRNO_TO_PARA_ERROR(EINVAL);
 228         if (btr_get_input_queue_size(btrn) != 0)
 229                 return -ERRNO_TO_PARA_ERROR(EINVAL);
 230         PARA_NOTICE_LOG("splicing out %s\n", btrn->name);
 231         if (btrn->parent)
 232                 list_del(&btrn->node);
 233         FOR_EACH_CHILD(ch, btrn)
 234                 ch->parent = btrn->parent;
 235         free(btrn->name);
 236         free(btrn);
 237         return 1;
 238 }
 239
 240 /**
 241  * Return the size of the largest input queue.
 242  *
 243  * Iterates over all children of the given node.
 244  */
 245 size_t btr_bytes_pending(struct btr_node *btrn)
 246 {
 247         size_t max_size = 0;
 248         struct btr_node *ch;
 249
 250         FOR_EACH_CHILD(ch, btrn) {
 251                 size_t size = btr_get_input_queue_size(ch);
 252                 max_size = PARA_MAX(max_size, size);
 253         }
 254         return max_size;
 255 }
 256
 257 int btr_exec(struct btr_node *btrn, const char *command, char **value_result)
 258 {
 259         if (!btrn)
 260                 return -ERRNO_TO_PARA_ERROR(EINVAL);
 261         if (!btrn->execute)
 262                 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
 263         return btrn->execute(btrn, command, value_result);
 264 }
 265
 266 int btr_exec_up(struct btr_node *btrn, const char *command, char **value_result)
 267 {
 268         int ret;
 269
 270         for (; btrn; btrn = btrn->parent) {
 271                 struct btr_node *parent = btrn->parent;
 272                 PARA_CRIT_LOG("parent: %p\n", parent);
 273                 if (!parent)
 274                         return -ERRNO_TO_PARA_ERROR(ENOTSUP);
 275                 if (!parent->execute)
 276                         continue;
 277                 ret = parent->execute(parent, command, value_result);
 278                 if (ret == -ERRNO_TO_PARA_ERROR(ENOTSUP))
 279                         continue;
 280                 if (ret < 0)
 281                         return ret;
 282         }
 283         return -ERRNO_TO_PARA_ERROR(ENOTSUP);
 284 }
 285
 286 void *btr_context(struct btr_node *btrn)
 287 {
 288         return btrn->context;
 289 }