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 };
  40
  41 #define FOR_EACH_CHILD(_tn, _btrn) list_for_each_entry((_tn), \
  42         &((_btrn)->children), node)
  43
  44 #define FOR_EACH_BUFFER_REF(_br, _btrn) \
  45         list_for_each_entry((_br), &(_btrn)->input_queue, node)
  46 #define FOR_EACH_BUFFER_REF_SAFE(_br, _tmp, _btrn) \
  47         list_for_each_entry_safe((_br), (_tmp), &(_btrn)->input_queue, node)
  48
  49 struct btr_node *btr_new_node(char *name, struct btr_node *parent,
  50                 btr_command_handler handler)
  51 {
  52         struct btr_node *btrn = para_malloc(sizeof(*btrn));
  53
  54         btrn->name = para_strdup(name);
  55         btrn->parent = parent;
  56         btrn->execute = handler;
  57         if (parent)
  58                 list_add_tail(&btrn->node, &parent->children);
  59         INIT_LIST_HEAD(&btrn->children);
  60         INIT_LIST_HEAD(&btrn->input_queue);
  61         return btrn;
  62 }
  63
  64 /*
  65  * Allocate a new btr buffer.
  66  *
  67  * The freshly allocated buffer will have a zero refcount.
  68  */
  69 static struct btr_buffer *new_btrb(char *buf, size_t size)
  70 {
  71         struct btr_buffer *btrb = para_malloc(sizeof(*btrb));
  72
  73         btrb->buf = buf;
  74         btrb->size = size;
  75         btrb->refcount = 0;
  76         return btrb;
  77 }
  78
  79 /*
  80  * Deallocate the reference, release the resources if refcount drops to zero.
  81  */
  82 static void btr_drop_buffer_reference(struct btr_buffer_reference *br)
  83 {
  84         struct btr_buffer *btrb = br->btrb;
  85
  86         //PARA_CRIT_LOG("dropping buffer reference %p\n", br);
  87         list_del(&br->node);
  88         free(br);
  89         btrb->refcount--;
  90         if (btrb->refcount == 0) {
  91                 free(btrb->buf);
  92                 free(btrb);
  93         }
  94 }
  95
  96 static void add_btrb_to_children(struct btr_buffer *btrb, struct btr_node *btrn)
  97 {
  98         struct btr_node *ch;
  99
 100         FOR_EACH_CHILD(ch, btrn) {
 101                 struct btr_buffer_reference *br = para_malloc(sizeof(*br));
 102                 br->btrb = btrb;
 103                 br->consumed = 0;
 104                 list_add_tail(&br->node, &ch->input_queue);
 105                 btrb->refcount++;
 106         }
 107 }
 108
 109 void btr_add_output(char *buf, size_t size, struct btr_node *btrn)
 110 {
 111         struct btr_buffer *btrb;
 112
 113         btrb = new_btrb(buf, size);
 114         add_btrb_to_children(btrb, btrn);
 115 }
 116
 117 static void btr_pushdown_br(struct btr_buffer_reference *br, struct btr_node *btrn)
 118 {
 119         add_btrb_to_children(br->btrb, btrn);
 120         btr_drop_buffer_reference(br);
 121 }
 122
 123 void btr_pushdown(struct btr_node *btrn)
 124 {
 125         struct btr_buffer_reference *br, *tmp;
 126
 127         FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
 128                 btr_pushdown_br(br, btrn);
 129 }
 130
 131 /* Return true if this node has no children. */
 132 bool btr_no_children(struct btr_node *btrn)
 133 {
 134         return list_empty(&btrn->children);
 135 }
 136
 137 bool btr_no_parent(struct btr_node *btrn)
 138 {
 139         return !btrn->parent;
 140 }
 141
 142 bool btr_inplace_ok(struct btr_node *btrn)
 143 {
 144         if (!btrn->parent)
 145                 return true;
 146         return list_is_singular(&btrn->parent->children);
 147 }
 148
 149 static inline size_t br_available_bytes(struct btr_buffer_reference *br)
 150 {
 151         return br->btrb->size - br->consumed;
 152 }
 153
 154 size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf)
 155 {
 156         *buf = br->btrb->buf + br->consumed;
 157         return br_available_bytes(br);
 158 }
 159
 160 size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
 161 {
 162         struct btr_buffer_reference *br;
 163
 164         if (list_empty(&btrn->input_queue)) {
 165                 *bufp = NULL;
 166                 return 0;
 167         }
 168         br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
 169         return btr_get_buffer_by_reference(br, bufp);
 170 }
 171
 172 void btr_consume(struct btr_node *btrn, size_t numbytes)
 173 {
 174         struct btr_buffer_reference *br;
 175
 176         assert(!list_empty(&btrn->input_queue));
 177         br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
 178         assert(br->consumed + numbytes <= br->btrb->size);
 179         br->consumed += numbytes;
 180         if (br->consumed == br->btrb->size)
 181                 btr_drop_buffer_reference(br);
 182 }
 183
 184 static void flush_input_queue(struct btr_node *btrn)
 185 {
 186         struct btr_buffer_reference *br, *tmp;
 187         FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
 188                 btr_drop_buffer_reference(br);
 189 }
 190
 191 void btr_del_node(struct btr_node *btrn)
 192 {
 193         struct btr_node *ch;
 194
 195         if (!btrn)
 196                 return;
 197         PARA_NOTICE_LOG("deleting %s\n", btrn->name);
 198         FOR_EACH_CHILD(ch, btrn)
 199                 ch->parent = NULL;
 200         flush_input_queue(btrn);
 201         if (btrn->parent)
 202                 list_del(&btrn->node);
 203         free(btrn->name);
 204         free(btrn);
 205 }
 206
 207 size_t btr_get_input_queue_size(struct btr_node *btrn)
 208 {
 209         struct btr_buffer_reference *br;
 210         size_t size = 0;
 211
 212         FOR_EACH_BUFFER_REF(br, btrn) {
 213                 //PARA_CRIT_LOG("size: %zu\n", size);
 214                 size += br_available_bytes(br);
 215         }
 216         return size;
 217 }
 218
 219 int btr_splice_out_node(struct btr_node *btrn)
 220 {
 221         struct btr_node *ch;
 222
 223         if (!btrn)
 224                 return -ERRNO_TO_PARA_ERROR(EINVAL);
 225         if (btr_get_input_queue_size(btrn) != 0)
 226                 return -ERRNO_TO_PARA_ERROR(EINVAL);
 227         PARA_NOTICE_LOG("splicing out %s\n", btrn->name);
 228         if (btrn->parent)
 229                 list_del(&btrn->node);
 230         FOR_EACH_CHILD(ch, btrn)
 231                 ch->parent = btrn->parent;
 232         free(btrn->name);
 233         free(btrn);
 234         return 1;
 235 }
 236
 237 /**
 238  * Return the size of the largest input queue.
 239  *
 240  * Iterates over all children of the given node.
 241  */
 242 size_t btr_bytes_pending(struct btr_node *btrn)
 243 {
 244         size_t max_size = 0;
 245         struct btr_node *ch;
 246
 247         FOR_EACH_CHILD(ch, btrn) {
 248                 size_t size = btr_get_input_queue_size(ch);
 249                 max_size = PARA_MAX(max_size, size);
 250         }
 251         return max_size;
 252 }
 253
 254 int btr_exec(struct btr_node *btrn, const char *command, char **value_result)
 255 {
 256         if (!btrn)
 257                 return -ERRNO_TO_PARA_ERROR(EINVAL);
 258         if (!btrn->execute)
 259                 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
 260         return btrn->execute(command, value_result);
 261 }
 262
 263 int btr_exec_up(struct btr_node *btrn, const char *command, char **value_result)
 264 {
 265         int ret;
 266
 267         for (; btrn; btrn = btrn->parent) {
 268                 struct btr_node *parent = btrn->parent;
 269                 PARA_CRIT_LOG("parent: %p\n", parent);
 270                 if (!parent)
 271                         return -ERRNO_TO_PARA_ERROR(ENOTSUP);
 272                 if (!parent->execute)
 273                         continue;
 274                 ret = parent->execute(command, value_result);
 275                 if (ret == -ERRNO_TO_PARA_ERROR(ENOTSUP))
 276                         continue;
 277                 if (ret < 0)
 278                         return ret;
 279         }
 280         return -ERRNO_TO_PARA_ERROR(ENOTSUP);
 281 }