summaryrefslogtreecommitdiff
path: root/reftable/merged.c
blob: e5b53da6db3f060e67f7e712b6098b5f42d3e5a5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
/*
Copyright 2020 Google LLC

Use of this source code is governed by a BSD-style
license that can be found in the LICENSE file or at
https://developers.google.com/open-source/licenses/bsd
*/

#include "merged.h"

#include "constants.h"
#include "iter.h"
#include "pq.h"
#include "reader.h"
#include "record.h"
#include "generic.h"
#include "reftable-merged.h"
#include "reftable-error.h"
#include "system.h"

static int merged_iter_init(struct merged_iter *mi)
{
	int i = 0;
	for (i = 0; i < mi->stack_len; i++) {
		struct reftable_record rec = reftable_new_record(mi->typ);
		int err = iterator_next(&mi->stack[i], &rec);
		if (err < 0) {
			return err;
		}

		if (err > 0) {
			reftable_iterator_destroy(&mi->stack[i]);
			reftable_record_destroy(&rec);
		} else {
			struct pq_entry e = {
				.rec = rec,
				.index = i,
			};
			merged_iter_pqueue_add(&mi->pq, e);
		}
	}

	return 0;
}

static void merged_iter_close(void *p)
{
	struct merged_iter *mi = p;
	int i = 0;
	merged_iter_pqueue_release(&mi->pq);
	for (i = 0; i < mi->stack_len; i++) {
		reftable_iterator_destroy(&mi->stack[i]);
	}
	reftable_free(mi->stack);
}

static int merged_iter_advance_nonnull_subiter(struct merged_iter *mi,
					       size_t idx)
{
	struct reftable_record rec = reftable_new_record(mi->typ);
	struct pq_entry e = {
		.rec = rec,
		.index = idx,
	};
	int err = iterator_next(&mi->stack[idx], &rec);
	if (err < 0)
		return err;

	if (err > 0) {
		reftable_iterator_destroy(&mi->stack[idx]);
		reftable_record_destroy(&rec);
		return 0;
	}

	merged_iter_pqueue_add(&mi->pq, e);
	return 0;
}

static int merged_iter_advance_subiter(struct merged_iter *mi, size_t idx)
{
	if (iterator_is_null(&mi->stack[idx]))
		return 0;
	return merged_iter_advance_nonnull_subiter(mi, idx);
}

static int merged_iter_next_entry(struct merged_iter *mi,
				  struct reftable_record *rec)
{
	struct strbuf entry_key = STRBUF_INIT;
	struct pq_entry entry = { 0 };
	int err = 0;

	if (merged_iter_pqueue_is_empty(mi->pq))
		return 1;

	entry = merged_iter_pqueue_remove(&mi->pq);
	err = merged_iter_advance_subiter(mi, entry.index);
	if (err < 0)
		return err;

	/*
	  One can also use reftable as datacenter-local storage, where the ref
	  database is maintained in globally consistent database (eg.
	  CockroachDB or Spanner). In this scenario, replication delays together
	  with compaction may cause newer tables to contain older entries. In
	  such a deployment, the loop below must be changed to collect all
	  entries for the same key, and return new the newest one.
	*/
	reftable_record_key(&entry.rec, &entry_key);
	while (!merged_iter_pqueue_is_empty(mi->pq)) {
		struct pq_entry top = merged_iter_pqueue_top(mi->pq);
		struct strbuf k = STRBUF_INIT;
		int err = 0, cmp = 0;

		reftable_record_key(&top.rec, &k);

		cmp = strbuf_cmp(&k, &entry_key);
		strbuf_release(&k);

		if (cmp > 0) {
			break;
		}

		merged_iter_pqueue_remove(&mi->pq);
		err = merged_iter_advance_subiter(mi, top.index);
		if (err < 0) {
			return err;
		}
		reftable_record_destroy(&top.rec);
	}

	reftable_record_copy_from(rec, &entry.rec, hash_size(mi->hash_id));
	reftable_record_destroy(&entry.rec);
	strbuf_release(&entry_key);
	return 0;
}

static int merged_iter_next(struct merged_iter *mi, struct reftable_record *rec)
{
	while (1) {
		int err = merged_iter_next_entry(mi, rec);
		if (err == 0 && mi->suppress_deletions &&
		    reftable_record_is_deletion(rec)) {
			continue;
		}

		return err;
	}
}

static int merged_iter_next_void(void *p, struct reftable_record *rec)
{
	struct merged_iter *mi = p;
	if (merged_iter_pqueue_is_empty(mi->pq))
		return 1;

	return merged_iter_next(mi, rec);
}

static struct reftable_iterator_vtable merged_iter_vtable = {
	.next = &merged_iter_next_void,
	.close = &merged_iter_close,
};

static void iterator_from_merged_iter(struct reftable_iterator *it,
				      struct merged_iter *mi)
{
	assert(!it->ops);
	it->iter_arg = mi;
	it->ops = &merged_iter_vtable;
}

int reftable_new_merged_table(struct reftable_merged_table **dest,
			      struct reftable_table *stack, int n,
			      uint32_t hash_id)
{
	struct reftable_merged_table *m = NULL;
	uint64_t last_max = 0;
	uint64_t first_min = 0;
	int i = 0;
	for (i = 0; i < n; i++) {
		uint64_t min = reftable_table_min_update_index(&stack[i]);
		uint64_t max = reftable_table_max_update_index(&stack[i]);

		if (reftable_table_hash_id(&stack[i]) != hash_id) {
			return REFTABLE_FORMAT_ERROR;
		}
		if (i == 0 || min < first_min) {
			first_min = min;
		}
		if (i == 0 || max > last_max) {
			last_max = max;
		}
	}

	m = reftable_calloc(sizeof(struct reftable_merged_table));
	m->stack = stack;
	m->stack_len = n;
	m->min = first_min;
	m->max = last_max;
	m->hash_id = hash_id;
	*dest = m;
	return 0;
}

/* clears the list of subtable, without affecting the readers themselves. */
void merged_table_release(struct reftable_merged_table *mt)
{
	FREE_AND_NULL(mt->stack);
	mt->stack_len = 0;
}

void reftable_merged_table_free(struct reftable_merged_table *mt)
{
	if (!mt) {
		return;
	}
	merged_table_release(mt);
	reftable_free(mt);
}

uint64_t
reftable_merged_table_max_update_index(struct reftable_merged_table *mt)
{
	return mt->max;
}

uint64_t
reftable_merged_table_min_update_index(struct reftable_merged_table *mt)
{
	return mt->min;
}

static int reftable_table_seek_record(struct reftable_table *tab,
				      struct reftable_iterator *it,
				      struct reftable_record *rec)
{
	return tab->ops->seek_record(tab->table_arg, it, rec);
}

static int merged_table_seek_record(struct reftable_merged_table *mt,
				    struct reftable_iterator *it,
				    struct reftable_record *rec)
{
	struct reftable_iterator *iters = reftable_calloc(
		sizeof(struct reftable_iterator) * mt->stack_len);
	struct merged_iter merged = {
		.stack = iters,
		.typ = reftable_record_type(rec),
		.hash_id = mt->hash_id,
		.suppress_deletions = mt->suppress_deletions,
	};
	int n = 0;
	int err = 0;
	int i = 0;
	for (i = 0; i < mt->stack_len && err == 0; i++) {
		int e = reftable_table_seek_record(&mt->stack[i], &iters[n],
						   rec);
		if (e < 0) {
			err = e;
		}
		if (e == 0) {
			n++;
		}
	}
	if (err < 0) {
		int i = 0;
		for (i = 0; i < n; i++) {
			reftable_iterator_destroy(&iters[i]);
		}
		reftable_free(iters);
		return err;
	}

	merged.stack_len = n;
	err = merged_iter_init(&merged);
	if (err < 0) {
		merged_iter_close(&merged);
		return err;
	} else {
		struct merged_iter *p =
			reftable_malloc(sizeof(struct merged_iter));
		*p = merged;
		iterator_from_merged_iter(it, p);
	}
	return 0;
}

int reftable_merged_table_seek_ref(struct reftable_merged_table *mt,
				   struct reftable_iterator *it,
				   const char *name)
{
	struct reftable_ref_record ref = {
		.refname = (char *)name,
	};
	struct reftable_record rec = { NULL };
	reftable_record_from_ref(&rec, &ref);
	return merged_table_seek_record(mt, it, &rec);
}

int reftable_merged_table_seek_log_at(struct reftable_merged_table *mt,
				      struct reftable_iterator *it,
				      const char *name, uint64_t update_index)
{
	struct reftable_log_record log = {
		.refname = (char *)name,
		.update_index = update_index,
	};
	struct reftable_record rec = { NULL };
	reftable_record_from_log(&rec, &log);
	return merged_table_seek_record(mt, it, &rec);
}

int reftable_merged_table_seek_log(struct reftable_merged_table *mt,
				   struct reftable_iterator *it,
				   const char *name)
{
	uint64_t max = ~((uint64_t)0);
	return reftable_merged_table_seek_log_at(mt, it, name, max);
}

uint32_t reftable_merged_table_hash_id(struct reftable_merged_table *mt)
{
	return mt->hash_id;
}

static int reftable_merged_table_seek_void(void *tab,
					   struct reftable_iterator *it,
					   struct reftable_record *rec)
{
	return merged_table_seek_record(tab, it, rec);
}

static uint32_t reftable_merged_table_hash_id_void(void *tab)
{
	return reftable_merged_table_hash_id(tab);
}

static uint64_t reftable_merged_table_min_update_index_void(void *tab)
{
	return reftable_merged_table_min_update_index(tab);
}

static uint64_t reftable_merged_table_max_update_index_void(void *tab)
{
	return reftable_merged_table_max_update_index(tab);
}

static struct reftable_table_vtable merged_table_vtable = {
	.seek_record = reftable_merged_table_seek_void,
	.hash_id = reftable_merged_table_hash_id_void,
	.min_update_index = reftable_merged_table_min_update_index_void,
	.max_update_index = reftable_merged_table_max_update_index_void,
};

void reftable_table_from_merged_table(struct reftable_table *tab,
				      struct reftable_merged_table *merged)
{
	assert(!tab->ops);
	tab->ops = &merged_table_vtable;
	tab->table_arg = merged;
}