Add btr_bytes_pending().
[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
9
10 struct btr_buffer {
11 char *buf;
12 size_t size;
13 /** The number of references to this buffer. */
14 int refcount;
15 };
16
17 struct btr_buffer_reference {
18 struct btr_buffer *btrb;
19 size_t consumed;
20 /* Each buffer reference belongs to the buffer queue list of some buffer tree node. */
21 struct list_head node;
22 };
23
24 struct btr_node {
25 char *name;
26 struct btr_node *parent;
27 /* The position of this btr node in the buffer tree. */
28 struct list_head node;
29 /* The children nodes of this btr node are linked together in a list. */
30 struct list_head children;
31 /**
32 * The input queue is a list of references to btr buffers. Each item on
33 * the list represents an input buffer which has not been completely
34 * used by this btr node.
35 */
36 struct list_head input_queue;
37 };
38
39 #define FOR_EACH_CHILD(_tn, _btrn) list_for_each_entry((_tn), \
40 &((_btrn)->children), node)
41
42 #define FOR_EACH_BUFFER_REF(_br, _btrn) \
43 list_for_each_entry((_br), &(_btrn)->input_queue, node)
44 #define FOR_EACH_BUFFER_REF_SAFE(_br, _tmp, _btrn) \
45 list_for_each_entry_safe((_br), (_tmp), &(_btrn)->input_queue, node)
46
47 struct btr_node *btr_new_node(char *name, struct btr_node *parent)
48 {
49 struct btr_node *btrn = para_malloc(sizeof(*btrn));
50
51 btrn->name = para_strdup(name);
52 btrn->parent = parent;
53 if (parent)
54 list_add_tail(&btrn->node, &parent->children);
55 INIT_LIST_HEAD(&btrn->children);
56 INIT_LIST_HEAD(&btrn->input_queue);
57 return btrn;
58 }
59
60 /*
61 * Allocate a new btr buffer.
62 *
63 * The freshly allocated buffer will have a zero refcount.
64 */
65 static struct btr_buffer *new_btrb(char *buf, size_t size)
66 {
67 struct btr_buffer *btrb = para_malloc(sizeof(*btrb));
68
69 btrb->buf = buf;
70 btrb->size = size;
71 btrb->refcount = 0;
72 return btrb;
73 }
74
75 /*
76 * Deallocate the reference, release the resources if refcount drops to zero.
77 */
78 static void btr_drop_buffer_reference(struct btr_buffer_reference *br)
79 {
80 struct btr_buffer *btrb = br->btrb;
81
82 list_del(&br->node);
83 free(br);
84 btrb->refcount--;
85 if (btrb->refcount == 0) {
86 free(btrb->buf);
87 free(btrb);
88 }
89 }
90
91 static void add_btrb_to_children(struct btr_buffer *btrb, struct btr_node *btrn)
92 {
93 struct btr_node *ch;
94
95 FOR_EACH_CHILD(ch, btrn) {
96 struct btr_buffer_reference *br = para_malloc(sizeof(*br));
97 br->btrb = btrb;
98 br->consumed = 0;
99 list_add_tail(&br->node, &ch->input_queue);
100 btrb->refcount++;
101 }
102 }
103
104 void btr_add_output(char *buf, size_t size, struct btr_node *btrn)
105 {
106 struct btr_buffer *btrb;
107
108 btrb = new_btrb(buf, size);
109 add_btrb_to_children(btrb, btrn);
110 }
111
112 static void btr_pushdown_br(struct btr_buffer_reference *br, struct btr_node *btrn)
113 {
114 add_btrb_to_children(br->btrb, btrn);
115 btr_drop_buffer_reference(br);
116 }
117
118 void btr_pushdown(struct btr_node *btrn)
119 {
120 struct btr_buffer_reference *br, *tmp;
121
122 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
123 btr_pushdown_br(br, btrn);
124 }
125
126 /* Return true if this node has no children. */
127 bool btr_is_leaf_node(struct btr_node *btrn)
128 {
129 return list_empty(&btrn->children);
130 }
131
132 bool btr_no_parent(struct btr_node *btrn)
133 {
134 return !btrn->parent;
135 }
136
137 bool btr_inplace_ok(struct btr_node *btrn)
138 {
139 if (!btrn->parent)
140 return true;
141 return list_is_singular(&btrn->parent->children);
142 }
143
144 struct btr_buffer_reference *btr_next_br(struct btr_node *btrn)
145 {
146 if (list_empty(&btrn->input_queue))
147 return NULL;
148 return list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
149 }
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 void btr_increase_used_bytes(struct btr_buffer_reference *br, size_t consumed)
164 {
165 br->consumed += consumed;
166 if (br->consumed == br->btrb->size)
167 btr_drop_buffer_reference(br);
168 }
169
170 static void flush_input_queue(struct btr_node *btrn)
171 {
172 struct btr_buffer_reference *br, *tmp;
173 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
174 btr_drop_buffer_reference(br);
175 }
176
177 void btr_del_node(struct btr_node *btrn)
178 {
179 struct btr_node *ch;
180
181 FOR_EACH_CHILD(ch, btrn)
182 ch->parent = NULL;
183 flush_input_queue(btrn);
184 if (btrn->parent)
185 list_del(&btrn->node);
186 free(btrn->name);
187 free(btrn);
188 }
189
190 size_t btr_get_input_queue_size(struct btr_node *btrn)
191 {
192 struct btr_buffer_reference *br;
193 size_t size = 0;
194
195 FOR_EACH_BUFFER_REF(br, btrn)
196 size += br_available_bytes(br);
197 return size;
198 }
199
200 /**
201 * Return the size of the largest input queue.
202 *
203 * Iterates over all children of the given node.
204 */
205 size_t btr_bytes_pending(struct btr_node *btrn)
206 {
207 size_t max_size = 0;
208 struct btr_node *ch;
209
210 FOR_EACH_CHILD(ch, btrn) {
211 size_t size = btr_get_input_queue_size(ch);
212 max_size = PARA_MAX(max_size, size);
213 }
214 return max_size;
215 }