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1 | /* |
2 | * index.c: Implementation of index.h. |
3 | */ |
4 | |
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5 | #include "agedu.h" |
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6 | #include "trie.h" |
7 | #include "index.h" |
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8 | #include "alloc.h" |
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9 | |
10 | #define alignof(typ) ( offsetof(struct { char c; typ t; }, t) ) |
11 | |
12 | #define min(x,y) ((x)<(y) ? (x):(y)) |
13 | #define max(x,y) ((x)>(y) ? (x):(y)) |
14 | |
15 | #define PADDING(x, mod) ( ((mod) - ((x) % (mod))) % (mod) ) |
16 | |
17 | struct avlnode { |
18 | off_t children[2], element; |
19 | int maxdepth; /* maximum depth of this subtree */ |
20 | unsigned long long totalsize; |
21 | }; |
22 | |
23 | static int index_navlnodes(int nodecount) |
24 | { |
25 | int b, c, maxdepth, ret; |
26 | |
27 | /* |
28 | * Model the tree growing at maximum imbalance. We do this by |
29 | * determining the number of nodes in the most unbalanced |
30 | * (i.e. smallest) tree of any given depth, and stopping when |
31 | * that's larger than nodecount. |
32 | */ |
33 | ret = 0; |
34 | maxdepth = 1; |
35 | b = 0; |
36 | c = 1; |
37 | while (b <= nodecount) { |
38 | int tmp; |
39 | |
40 | /* |
41 | * A tree with at most b nodes can be at most depth |
42 | * maxdepth-1. A tree with more than b but at most c can |
43 | * be at most maxdepth. Therefore, for each tree size |
44 | * between b and c, we might need to adjust maxdepth+1 |
45 | * nodes. |
46 | */ |
47 | tmp = min(c, nodecount); |
48 | ret += (tmp - b) * maxdepth; |
49 | |
50 | tmp = 1 + b + c; |
51 | b = c; |
52 | c = tmp; |
53 | maxdepth++; |
54 | } |
55 | |
56 | return ret; |
57 | } |
58 | |
59 | off_t index_compute_size(off_t currentsize, int nodecount) |
60 | { |
61 | currentsize += PADDING(currentsize, alignof(off_t)); |
62 | currentsize += nodecount + sizeof(off_t); |
63 | currentsize += PADDING(currentsize, alignof(struct avlnode)); |
64 | currentsize += index_navlnodes(nodecount) * sizeof(struct avlnode); |
65 | |
66 | return currentsize; |
67 | } |
68 | |
69 | /* ---------------------------------------------------------------------- |
70 | * Functions to build the index. |
71 | */ |
72 | |
73 | struct indexbuild { |
74 | void *t; |
75 | int n, nnodes, maxnodes; |
76 | struct avlnode *nodes; |
77 | off_t *roots; |
78 | struct avlnode *currroot; |
79 | struct avlnode *firstmutable; |
80 | }; |
81 | |
82 | #define ELEMENT(t,offset) \ |
83 | ((offset) ? (struct trie_file *)((char *)(t) + (offset)) : NULL) |
84 | #define NODE(t,offset) \ |
85 | ((offset) ? (struct avlnode *)((char *)(t) + (offset)) : NULL) |
86 | #define OFFSET(t,node) \ |
87 | ((node) ? (off_t)((const char *)node - (const char *)t) : 0) |
88 | #define MAXDEPTH(node) ((node) ? (node)->maxdepth : 0) |
89 | |
90 | indexbuild *indexbuild_new(void *t, off_t startoff, int nodecount) |
91 | { |
92 | indexbuild *ib = snew(indexbuild); |
93 | |
94 | ib->t = t; |
95 | startoff += PADDING(startoff, alignof(off_t)); |
96 | ib->roots = (off_t *)((char *)t + startoff); |
97 | trie_set_index_offset(t, startoff); |
98 | startoff += nodecount * sizeof(off_t); |
99 | startoff += PADDING(startoff, alignof(struct avlnode)); |
100 | ib->nodes = (struct avlnode *)((char *)t + startoff); |
101 | ib->maxnodes = index_navlnodes(nodecount); |
102 | ib->nnodes = ib->n = 0; |
103 | ib->currroot = NULL; |
104 | ib->firstmutable = ib->nodes + ib->nnodes; |
105 | |
106 | return ib; |
107 | } |
108 | |
109 | /* |
110 | * Return a mutable node, which is n or a copy of n if n is |
111 | * non-NULL. |
112 | */ |
113 | static struct avlnode *avl_makemutable(indexbuild *ib, struct avlnode *n) |
114 | { |
115 | struct avlnode *newnode; |
116 | |
117 | if (n && n >= ib->firstmutable) |
118 | return n; /* already mutable */ |
119 | |
120 | assert(ib->nnodes < ib->maxnodes); |
121 | newnode = ib->nodes + ib->nnodes++; |
122 | if (n) |
123 | *newnode = *n; /* structure copy */ |
124 | return newnode; |
125 | } |
126 | |
127 | /* |
128 | * Fix the annotations in a tree node. |
129 | */ |
130 | static void avl_fix(indexbuild *ib, struct avlnode *n) |
131 | { |
132 | /* |
133 | * Make sure the max depth field is right. |
134 | */ |
135 | n->maxdepth = 1 + max(MAXDEPTH(NODE(ib->t, n->children[0])), |
136 | MAXDEPTH(NODE(ib->t, n->children[1]))); |
137 | |
138 | n->totalsize = |
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139 | (ELEMENT(ib->t, n->element)->size + |
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140 | (n->children[0] ? NODE(ib->t, n->children[0])->totalsize : 0) + |
141 | (n->children[1] ? NODE(ib->t, n->children[1])->totalsize : 0)); |
142 | } |
143 | |
144 | static struct avlnode *avl_insert(indexbuild *ib, struct avlnode *n, |
145 | off_t node) |
146 | { |
147 | struct trie_file *newfile; |
148 | struct trie_file *oldfile; |
149 | int subtree; |
150 | struct avlnode *nn; |
151 | |
152 | /* |
153 | * Recursion bottoming out: if the subtree we're inserting |
154 | * into is null, just construct and return a fresh node. |
155 | */ |
156 | if (!n) { |
157 | n = avl_makemutable(ib, NULL); |
158 | n->children[0] = n->children[1] = 0; |
159 | n->element = node; |
160 | avl_fix(ib, n); |
161 | return n; |
162 | } |
163 | |
164 | /* |
165 | * Otherwise, we have to insert into an existing tree. |
166 | */ |
167 | |
168 | /* |
169 | * Determine which subtree to insert this node into. Ties |
170 | * aren't important, so we just break them any old way. |
171 | */ |
172 | newfile = (struct trie_file *)((char *)ib->t + node); |
173 | oldfile = (struct trie_file *)((char *)ib->t + n->element); |
174 | if (newfile->atime > oldfile->atime) |
175 | subtree = 1; |
176 | else |
177 | subtree = 0; |
178 | |
179 | /* |
180 | * Construct a copy of the node we're looking at. |
181 | */ |
182 | n = avl_makemutable(ib, n); |
183 | |
184 | /* |
185 | * Recursively insert into the next subtree down. |
186 | */ |
187 | nn = avl_insert(ib, NODE(ib->t, n->children[subtree]), node); |
188 | n->children[subtree] = OFFSET(ib->t, nn); |
189 | |
190 | /* |
191 | * Rebalance if necessary, to ensure that our node's children |
192 | * differ in maximum depth by at most one. Of course, the |
193 | * subtree we've just modified will be the deeper one if so. |
194 | */ |
195 | if (MAXDEPTH(NODE(ib->t, n->children[subtree])) > |
196 | MAXDEPTH(NODE(ib->t, n->children[1-subtree])) + 1) { |
197 | struct avlnode *p, *q; |
198 | |
199 | /* |
200 | * There are two possible cases, one of which requires a |
201 | * single tree rotation and the other requires two. It all |
202 | * depends on which subtree of the next node down (here p) |
203 | * is the taller. (It turns out that they can't both be |
204 | * the same height: any tree which has just increased in |
205 | * depth must have one subtree strictly taller than the |
206 | * other.) |
207 | */ |
208 | p = NODE(ib->t, n->children[subtree]); |
209 | assert(p >= ib->firstmutable); |
210 | if (MAXDEPTH(NODE(ib->t, p->children[subtree])) >= |
211 | MAXDEPTH(NODE(ib->t, p->children[1-subtree]))) { |
212 | /* |
213 | * n p |
214 | * / \ / \ |
215 | * [k] p -> n [k+1] |
216 | * / \ / \ |
217 | * [k] [k+1] [k] [k] |
218 | */ |
219 | n->children[subtree] = p->children[1-subtree]; |
220 | p->children[1-subtree] = OFFSET(ib->t, n); |
221 | avl_fix(ib, n); |
222 | n = p; |
223 | } else { |
224 | q = NODE(ib->t, p->children[1-subtree]); |
225 | assert(q >= ib->firstmutable); |
226 | p->children[1-subtree] = OFFSET(ib->t, q); |
227 | /* |
228 | * n n q |
229 | * / \ / \ / \ |
230 | * [k] p == [k] p -> n p |
231 | * / \ / \ / \ / \ |
232 | * [k+1] [k] q [k] [k] \ / [k] |
233 | * / \ [k-1,k] [k-1,k] |
234 | * [k-1,k] [k-1,k] |
235 | */ |
236 | n->children[subtree] = q->children[1-subtree]; |
237 | p->children[1-subtree] = q->children[subtree]; |
238 | q->children[1-subtree] = OFFSET(ib->t, n); |
239 | q->children[subtree] = OFFSET(ib->t, p); |
240 | avl_fix(ib, n); |
241 | avl_fix(ib, p); |
242 | n = q; |
243 | } |
244 | } |
245 | |
246 | /* |
247 | * Fix up our maximum depth field. |
248 | */ |
249 | avl_fix(ib, n); |
250 | |
251 | /* |
252 | * Done. |
253 | */ |
254 | return n; |
255 | } |
256 | |
257 | void indexbuild_add(indexbuild *ib, const struct trie_file *tf) |
258 | { |
259 | off_t node = OFFSET(ib->t, tf); |
260 | ib->currroot = avl_insert(ib, ib->currroot, node); |
261 | ib->roots[ib->n++] = OFFSET(ib->t, ib->currroot); |
262 | ib->firstmutable = ib->nodes + ib->nnodes; |
263 | } |
264 | |
265 | off_t indexbuild_realsize(indexbuild *ib) |
266 | { |
267 | return OFFSET(ib->t, (ib->nodes + ib->nnodes)); |
268 | } |
269 | |
270 | void indexbuild_free(indexbuild *ib) |
271 | { |
272 | sfree(ib); |
273 | } |
274 | |
275 | unsigned long long index_query(const void *t, int n, unsigned long long at) |
276 | { |
277 | const off_t *roots; |
278 | const struct avlnode *node; |
279 | unsigned long count; |
280 | unsigned long long ret; |
281 | |
282 | roots = (const off_t *)((const char *)t + trie_get_index_offset(t)); |
283 | |
284 | if (n < 1) |
285 | return 0; |
286 | count = trie_count(t); |
287 | if (n > count) |
288 | n = count; |
289 | |
290 | node = NODE(t, roots[n-1]); |
291 | |
292 | ret = 0; |
293 | |
294 | while (node) { |
295 | const struct trie_file *tf = ELEMENT(t, node->element); |
296 | const struct avlnode *left = NODE(t, node->children[0]); |
297 | const struct avlnode *right = NODE(t, node->children[1]); |
298 | |
299 | if (at <= tf->atime) { |
300 | node = left; |
301 | } else { |
302 | if (left) |
303 | ret += left->totalsize; |
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304 | ret += tf->size; |
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305 | node = right; |
306 | } |
307 | } |
308 | |
309 | return ret; |
310 | } |
311 | |
312 | unsigned long long index_order_stat(const void *t, double f) |
313 | { |
314 | const off_t *roots; |
315 | const struct avlnode *node; |
316 | unsigned long count; |
317 | unsigned long long size; |
318 | |
319 | roots = (const off_t *)((const char *)t + trie_get_index_offset(t)); |
320 | count = trie_count(t); |
321 | node = NODE(t, roots[count-1]); |
322 | |
323 | size = node->totalsize * f; |
324 | assert(size <= node->totalsize); |
325 | |
326 | while (1) { |
327 | const struct trie_file *tf = ELEMENT(t, node->element); |
328 | const struct avlnode *left = NODE(t, node->children[0]); |
329 | const struct avlnode *right = NODE(t, node->children[1]); |
330 | |
331 | if (left && size < left->totalsize) { |
332 | node = left; |
333 | } else if (!right || |
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334 | size < (left ? left->totalsize : 0) + tf->size) { |
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335 | return tf->atime; |
336 | } else { |
337 | if (left) |
338 | size -= left->totalsize; |
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339 | size -= tf->size; |
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340 | node = right; |
341 | } |
342 | } |
343 | } |