diff options
Diffstat (limited to 'reftable/merged.c')
| -rw-r--r-- | reftable/merged.c | 361 |
1 files changed, 361 insertions, 0 deletions
diff --git a/reftable/merged.c b/reftable/merged.c new file mode 100644 index 0000000..2a6efa1 --- /dev/null +++ b/reftable/merged.c @@ -0,0 +1,361 @@ +/* +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_release(&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 pq_entry e = { + .rec = reftable_new_record(mi->typ), + .index = idx, + }; + int err = iterator_next(&mi->stack[idx], &e.rec); + if (err < 0) + return err; + + if (err > 0) { + reftable_iterator_destroy(&mi->stack[idx]); + reftable_record_release(&e.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_release(&top.rec); + } + + reftable_record_copy_from(rec, &entry.rec, hash_size(mi->hash_id)); + reftable_record_release(&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_record rec = { + .type = BLOCK_TYPE_REF, + .u.ref = { + .refname = (char *)name, + }, + }; + 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_record rec = { .type = BLOCK_TYPE_LOG, + .u.log = { + .refname = (char *)name, + .update_index = update_index, + } }; + 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; +} |