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1ae2b8cd HWN |
1 | /* |
2 | Copyright 2020 Google LLC | |
3 | ||
4 | Use of this source code is governed by a BSD-style | |
5 | license that can be found in the LICENSE file or at | |
6 | https://developers.google.com/open-source/licenses/bsd | |
7 | */ | |
8 | ||
9 | #include "merged.h" | |
10 | ||
11 | #include "constants.h" | |
12 | #include "iter.h" | |
13 | #include "pq.h" | |
1ae2b8cd HWN |
14 | #include "record.h" |
15 | #include "generic.h" | |
16 | #include "reftable-merged.h" | |
17 | #include "reftable-error.h" | |
18 | #include "system.h" | |
19 | ||
bb2d6be4 PS |
20 | struct merged_subiter { |
21 | struct reftable_iterator iter; | |
22 | struct reftable_record rec; | |
23 | }; | |
24 | ||
48929d2e | 25 | struct merged_iter { |
bb2d6be4 | 26 | struct merged_subiter *subiters; |
aad8ad6f | 27 | struct merged_iter_pqueue pq; |
48929d2e PS |
28 | uint32_t hash_id; |
29 | size_t stack_len; | |
30 | uint8_t typ; | |
31 | int suppress_deletions; | |
aad8ad6f | 32 | ssize_t advance_index; |
48929d2e PS |
33 | }; |
34 | ||
1ae2b8cd HWN |
35 | static int merged_iter_init(struct merged_iter *mi) |
36 | { | |
62d3c8e8 PS |
37 | for (size_t i = 0; i < mi->stack_len; i++) { |
38 | struct pq_entry e = { | |
62d3c8e8 | 39 | .index = i, |
bb2d6be4 | 40 | .rec = &mi->subiters[i].rec, |
62d3c8e8 PS |
41 | }; |
42 | int err; | |
43 | ||
bb2d6be4 PS |
44 | reftable_record_init(&mi->subiters[i].rec, mi->typ); |
45 | err = iterator_next(&mi->subiters[i].iter, | |
46 | &mi->subiters[i].rec); | |
62d3c8e8 | 47 | if (err < 0) |
1ae2b8cd | 48 | return err; |
3b6dd6ad | 49 | if (err > 0) |
62d3c8e8 | 50 | continue; |
62d3c8e8 PS |
51 | |
52 | merged_iter_pqueue_add(&mi->pq, &e); | |
1ae2b8cd HWN |
53 | } |
54 | ||
55 | return 0; | |
56 | } | |
57 | ||
58 | static void merged_iter_close(void *p) | |
59 | { | |
60 | struct merged_iter *mi = p; | |
81879123 | 61 | |
1ae2b8cd | 62 | merged_iter_pqueue_release(&mi->pq); |
bb2d6be4 PS |
63 | for (size_t i = 0; i < mi->stack_len; i++) { |
64 | reftable_iterator_destroy(&mi->subiters[i].iter); | |
65 | reftable_record_release(&mi->subiters[i].rec); | |
66 | } | |
67 | reftable_free(mi->subiters); | |
1ae2b8cd HWN |
68 | } |
69 | ||
2d71a1d4 | 70 | static int merged_iter_advance_subiter(struct merged_iter *mi, size_t idx) |
1ae2b8cd | 71 | { |
1ae2b8cd | 72 | struct pq_entry e = { |
1ae2b8cd | 73 | .index = idx, |
bb2d6be4 | 74 | .rec = &mi->subiters[idx].rec, |
1ae2b8cd | 75 | }; |
3ddef475 PS |
76 | int err; |
77 | ||
bb2d6be4 | 78 | err = iterator_next(&mi->subiters[idx].iter, &mi->subiters[idx].rec); |
3b6dd6ad | 79 | if (err) |
1ae2b8cd | 80 | return err; |
1ae2b8cd | 81 | |
c18eecbe | 82 | merged_iter_pqueue_add(&mi->pq, &e); |
1ae2b8cd HWN |
83 | return 0; |
84 | } | |
85 | ||
1ae2b8cd HWN |
86 | static int merged_iter_next_entry(struct merged_iter *mi, |
87 | struct reftable_record *rec) | |
88 | { | |
1ae2b8cd | 89 | struct pq_entry entry = { 0 }; |
f8c1a8e2 PS |
90 | int err = 0, empty; |
91 | ||
92 | empty = merged_iter_pqueue_is_empty(mi->pq); | |
1ae2b8cd | 93 | |
aad8ad6f | 94 | if (mi->advance_index >= 0) { |
f8c1a8e2 PS |
95 | /* |
96 | * When there are no pqueue entries then we only have a single | |
97 | * subiter left. There is no need to use the pqueue in that | |
98 | * case anymore as we know that the subiter will return entries | |
99 | * in the correct order already. | |
100 | * | |
101 | * While this may sound like a very specific edge case, it may | |
102 | * happen more frequently than you think. Most repositories | |
103 | * will end up having a single large base table that contains | |
104 | * most of the refs. It's thus likely that we exhaust all | |
105 | * subiters but the one from that base ref. | |
106 | */ | |
107 | if (empty) | |
108 | return iterator_next(&mi->subiters[mi->advance_index].iter, | |
109 | rec); | |
110 | ||
aad8ad6f PS |
111 | err = merged_iter_advance_subiter(mi, mi->advance_index); |
112 | if (err < 0) | |
113 | return err; | |
f8c1a8e2 PS |
114 | if (!err) |
115 | empty = 0; | |
aad8ad6f PS |
116 | mi->advance_index = -1; |
117 | } | |
118 | ||
f8c1a8e2 | 119 | if (empty) |
1ae2b8cd HWN |
120 | return 1; |
121 | ||
122 | entry = merged_iter_pqueue_remove(&mi->pq); | |
1ae2b8cd HWN |
123 | |
124 | /* | |
125 | One can also use reftable as datacenter-local storage, where the ref | |
126 | database is maintained in globally consistent database (eg. | |
127 | CockroachDB or Spanner). In this scenario, replication delays together | |
128 | with compaction may cause newer tables to contain older entries. In | |
129 | such a deployment, the loop below must be changed to collect all | |
130 | entries for the same key, and return new the newest one. | |
131 | */ | |
1ae2b8cd HWN |
132 | while (!merged_iter_pqueue_is_empty(mi->pq)) { |
133 | struct pq_entry top = merged_iter_pqueue_top(mi->pq); | |
a96e9a20 | 134 | int cmp; |
1ae2b8cd | 135 | |
bb2d6be4 | 136 | cmp = reftable_record_cmp(top.rec, entry.rec); |
829231dc | 137 | if (cmp > 0) |
1ae2b8cd | 138 | break; |
1ae2b8cd HWN |
139 | |
140 | merged_iter_pqueue_remove(&mi->pq); | |
141 | err = merged_iter_advance_subiter(mi, top.index); | |
829231dc | 142 | if (err < 0) |
bb2d6be4 | 143 | return err; |
1ae2b8cd HWN |
144 | } |
145 | ||
aad8ad6f | 146 | mi->advance_index = entry.index; |
bb2d6be4 PS |
147 | SWAP(*rec, *entry.rec); |
148 | return 0; | |
1ae2b8cd HWN |
149 | } |
150 | ||
080f8c45 | 151 | static int merged_iter_next_void(void *p, struct reftable_record *rec) |
1ae2b8cd | 152 | { |
080f8c45 | 153 | struct merged_iter *mi = p; |
1ae2b8cd HWN |
154 | while (1) { |
155 | int err = merged_iter_next_entry(mi, rec); | |
080f8c45 PS |
156 | if (err) |
157 | return err; | |
158 | if (mi->suppress_deletions && reftable_record_is_deletion(rec)) | |
1ae2b8cd | 159 | continue; |
080f8c45 | 160 | return 0; |
1ae2b8cd HWN |
161 | } |
162 | } | |
163 | ||
1ae2b8cd HWN |
164 | static struct reftable_iterator_vtable merged_iter_vtable = { |
165 | .next = &merged_iter_next_void, | |
166 | .close = &merged_iter_close, | |
167 | }; | |
168 | ||
169 | static void iterator_from_merged_iter(struct reftable_iterator *it, | |
170 | struct merged_iter *mi) | |
171 | { | |
172 | assert(!it->ops); | |
173 | it->iter_arg = mi; | |
174 | it->ops = &merged_iter_vtable; | |
175 | } | |
176 | ||
177 | int reftable_new_merged_table(struct reftable_merged_table **dest, | |
81879123 | 178 | struct reftable_table *stack, size_t n, |
1ae2b8cd HWN |
179 | uint32_t hash_id) |
180 | { | |
181 | struct reftable_merged_table *m = NULL; | |
182 | uint64_t last_max = 0; | |
183 | uint64_t first_min = 0; | |
81879123 PS |
184 | |
185 | for (size_t i = 0; i < n; i++) { | |
1ae2b8cd HWN |
186 | uint64_t min = reftable_table_min_update_index(&stack[i]); |
187 | uint64_t max = reftable_table_max_update_index(&stack[i]); | |
188 | ||
189 | if (reftable_table_hash_id(&stack[i]) != hash_id) { | |
190 | return REFTABLE_FORMAT_ERROR; | |
191 | } | |
192 | if (i == 0 || min < first_min) { | |
193 | first_min = min; | |
194 | } | |
195 | if (i == 0 || max > last_max) { | |
196 | last_max = max; | |
197 | } | |
198 | } | |
199 | ||
b4ff12c8 | 200 | REFTABLE_CALLOC_ARRAY(m, 1); |
1ae2b8cd HWN |
201 | m->stack = stack; |
202 | m->stack_len = n; | |
203 | m->min = first_min; | |
204 | m->max = last_max; | |
205 | m->hash_id = hash_id; | |
206 | *dest = m; | |
207 | return 0; | |
208 | } | |
209 | ||
210 | /* clears the list of subtable, without affecting the readers themselves. */ | |
211 | void merged_table_release(struct reftable_merged_table *mt) | |
212 | { | |
213 | FREE_AND_NULL(mt->stack); | |
214 | mt->stack_len = 0; | |
215 | } | |
216 | ||
217 | void reftable_merged_table_free(struct reftable_merged_table *mt) | |
218 | { | |
219 | if (!mt) { | |
220 | return; | |
221 | } | |
222 | merged_table_release(mt); | |
223 | reftable_free(mt); | |
224 | } | |
225 | ||
226 | uint64_t | |
227 | reftable_merged_table_max_update_index(struct reftable_merged_table *mt) | |
228 | { | |
229 | return mt->max; | |
230 | } | |
231 | ||
232 | uint64_t | |
233 | reftable_merged_table_min_update_index(struct reftable_merged_table *mt) | |
234 | { | |
235 | return mt->min; | |
236 | } | |
237 | ||
238 | static int reftable_table_seek_record(struct reftable_table *tab, | |
239 | struct reftable_iterator *it, | |
240 | struct reftable_record *rec) | |
241 | { | |
242 | return tab->ops->seek_record(tab->table_arg, it, rec); | |
243 | } | |
244 | ||
245 | static int merged_table_seek_record(struct reftable_merged_table *mt, | |
246 | struct reftable_iterator *it, | |
247 | struct reftable_record *rec) | |
248 | { | |
1ae2b8cd | 249 | struct merged_iter merged = { |
1ae2b8cd HWN |
250 | .typ = reftable_record_type(rec), |
251 | .hash_id = mt->hash_id, | |
252 | .suppress_deletions = mt->suppress_deletions, | |
aad8ad6f | 253 | .advance_index = -1, |
1ae2b8cd | 254 | }; |
59f302ca PS |
255 | struct merged_iter *p; |
256 | int err; | |
257 | ||
bb2d6be4 | 258 | REFTABLE_CALLOC_ARRAY(merged.subiters, mt->stack_len); |
59f302ca PS |
259 | for (size_t i = 0; i < mt->stack_len; i++) { |
260 | err = reftable_table_seek_record(&mt->stack[i], | |
bb2d6be4 | 261 | &merged.subiters[merged.stack_len].iter, rec); |
59f302ca PS |
262 | if (err < 0) |
263 | goto out; | |
264 | if (!err) | |
265 | merged.stack_len++; | |
1ae2b8cd HWN |
266 | } |
267 | ||
1ae2b8cd | 268 | err = merged_iter_init(&merged); |
59f302ca PS |
269 | if (err < 0) |
270 | goto out; | |
271 | ||
272 | p = reftable_malloc(sizeof(struct merged_iter)); | |
273 | *p = merged; | |
274 | iterator_from_merged_iter(it, p); | |
275 | ||
276 | out: | |
277 | if (err < 0) | |
1ae2b8cd | 278 | merged_iter_close(&merged); |
59f302ca | 279 | return err; |
1ae2b8cd HWN |
280 | } |
281 | ||
282 | int reftable_merged_table_seek_ref(struct reftable_merged_table *mt, | |
283 | struct reftable_iterator *it, | |
284 | const char *name) | |
285 | { | |
66c0daba HWN |
286 | struct reftable_record rec = { |
287 | .type = BLOCK_TYPE_REF, | |
288 | .u.ref = { | |
289 | .refname = (char *)name, | |
290 | }, | |
1ae2b8cd | 291 | }; |
1ae2b8cd HWN |
292 | return merged_table_seek_record(mt, it, &rec); |
293 | } | |
294 | ||
295 | int reftable_merged_table_seek_log_at(struct reftable_merged_table *mt, | |
296 | struct reftable_iterator *it, | |
297 | const char *name, uint64_t update_index) | |
298 | { | |
66c0daba HWN |
299 | struct reftable_record rec = { .type = BLOCK_TYPE_LOG, |
300 | .u.log = { | |
301 | .refname = (char *)name, | |
302 | .update_index = update_index, | |
303 | } }; | |
1ae2b8cd HWN |
304 | return merged_table_seek_record(mt, it, &rec); |
305 | } | |
306 | ||
307 | int reftable_merged_table_seek_log(struct reftable_merged_table *mt, | |
308 | struct reftable_iterator *it, | |
309 | const char *name) | |
310 | { | |
311 | uint64_t max = ~((uint64_t)0); | |
312 | return reftable_merged_table_seek_log_at(mt, it, name, max); | |
313 | } | |
314 | ||
315 | uint32_t reftable_merged_table_hash_id(struct reftable_merged_table *mt) | |
316 | { | |
317 | return mt->hash_id; | |
318 | } | |
319 | ||
320 | static int reftable_merged_table_seek_void(void *tab, | |
321 | struct reftable_iterator *it, | |
322 | struct reftable_record *rec) | |
323 | { | |
324 | return merged_table_seek_record(tab, it, rec); | |
325 | } | |
326 | ||
327 | static uint32_t reftable_merged_table_hash_id_void(void *tab) | |
328 | { | |
329 | return reftable_merged_table_hash_id(tab); | |
330 | } | |
331 | ||
332 | static uint64_t reftable_merged_table_min_update_index_void(void *tab) | |
333 | { | |
334 | return reftable_merged_table_min_update_index(tab); | |
335 | } | |
336 | ||
337 | static uint64_t reftable_merged_table_max_update_index_void(void *tab) | |
338 | { | |
339 | return reftable_merged_table_max_update_index(tab); | |
340 | } | |
341 | ||
342 | static struct reftable_table_vtable merged_table_vtable = { | |
343 | .seek_record = reftable_merged_table_seek_void, | |
344 | .hash_id = reftable_merged_table_hash_id_void, | |
345 | .min_update_index = reftable_merged_table_min_update_index_void, | |
346 | .max_update_index = reftable_merged_table_max_update_index_void, | |
347 | }; | |
348 | ||
349 | void reftable_table_from_merged_table(struct reftable_table *tab, | |
350 | struct reftable_merged_table *merged) | |
351 | { | |
352 | assert(!tab->ops); | |
353 | tab->ops = &merged_table_vtable; | |
354 | tab->table_arg = merged; | |
355 | } |