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-rw-r--r--reftable/merged.c362
1 files changed, 362 insertions, 0 deletions
diff --git a/reftable/merged.c b/reftable/merged.c
new file mode 100644
index 0000000000..e5b53da6db
--- /dev/null
+++ b/reftable/merged.c
@@ -0,0 +1,362 @@
+/*
+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;
+}