[PATCH v3 15/19] reftable: add merged table view
- From
Han-Wen Nienhuys via GitGitGadget <gitgitgadget@gmail.com>
- Date
- Sep 28, 2021, 15:10 UTC
- Message-ID
- <40a91b14be89a53e6501cf34a4ca5dcf3c874dc6.1632841817.git.gitgitgadget@gmail.com>
- In-Reply-To
- <pull.1081.v3.git.git.1632841817.gitgitgadget@gmail.com>
From: Han-Wen Nienhuys <hanwen@google.com>
This adds an abstract, read-only interface to the ref database.
This primitive is used to construct the read view of the ref database (the read view is constructed by merging several *.ref files). It also provides the mechanism to provide a unified view of the refs in the main repository and the per-worktree refs.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> --- Makefile | 2 + reftable/merged.c | 362 +++++++++++++++++++++++++++++++++++++ reftable/merged.h | 35 ++++ reftable/merged_test.c | 292 ++++++++++++++++++++++++++++++ reftable/reftable-merged.h | 72 ++++++++ t/helper/test-reftable.c | 1 + 6 files changed, 764 insertions(+) create mode 100644 reftable/merged.c create mode 100644 reftable/merged.h create mode 100644 reftable/merged_test.c create mode 100644 reftable/reftable-merged.h
diff --git a/Makefile b/Makefile index 86509141558..d90aa25f764 100644 --- a/Makefile +++ b/Makefile @@ -2440,6 +2440,7 @@ REFTABLE_OBJS += reftable/block.o REFTABLE_OBJS += reftable/blocksource.o REFTABLE_OBJS += reftable/iter.o REFTABLE_OBJS += reftable/publicbasics.o +REFTABLE_OBJS += reftable/merged.o REFTABLE_OBJS += reftable/pq.o REFTABLE_OBJS += reftable/reader.o REFTABLE_OBJS += reftable/record.o @@ -2451,6 +2452,7 @@ REFTABLE_OBJS += reftable/writer.o REFTABLE_TEST_OBJS += reftable/basics_test.o REFTABLE_TEST_OBJS += reftable/block_test.o +REFTABLE_TEST_OBJS += reftable/merged_test.o REFTABLE_TEST_OBJS += reftable/pq_test.o REFTABLE_TEST_OBJS += reftable/record_test.o REFTABLE_TEST_OBJS += reftable/readwrite_test.o diff --git a/reftable/merged.c b/reftable/merged.c new file mode 100644 index 00000000000..e5b53da6db3 --- /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; +} diff --git a/reftable/merged.h b/reftable/merged.h new file mode 100644 index 00000000000..8c4d4d58d77 --- /dev/null +++ b/reftable/merged.h @@ -0,0 +1,35 @@ +/* +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 +*/ + +#ifndef MERGED_H +#define MERGED_H + +#include "pq.h" + +struct reftable_merged_table { + struct reftable_table *stack; + size_t stack_len; + uint32_t hash_id; + int suppress_deletions; + + uint64_t min; + uint64_t max; +}; + +struct merged_iter { + struct reftable_iterator *stack; + uint32_t hash_id; + size_t stack_len; + uint8_t typ; + int suppress_deletions; + struct merged_iter_pqueue pq; +}; + +void merged_table_release(struct reftable_merged_table *mt); + +#endif diff --git a/reftable/merged_test.c b/reftable/merged_test.c new file mode 100644 index 00000000000..da607401141 --- /dev/null +++ b/reftable/merged_test.c @@ -0,0 +1,292 @@ +/* +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 "system.h" + +#include "basics.h" +#include "blocksource.h" +#include "constants.h" +#include "reader.h" +#include "record.h" +#include "test_framework.h" +#include "reftable-merged.h" +#include "reftable-tests.h" +#include "reftable-generic.h" +#include "reftable-writer.h" + +static void write_test_table(struct strbuf *buf, + struct reftable_ref_record refs[], int n) +{ + int min = 0xffffffff; + int max = 0; + int i = 0; + int err; + + struct reftable_write_options opts = { + .block_size = 256, + }; + struct reftable_writer *w = NULL; + for (i = 0; i < n; i++) { + uint64_t ui = refs[i].update_index; + if (ui > max) { + max = ui; + } + if (ui < min) { + min = ui; + } + } + + w = reftable_new_writer(&strbuf_add_void, buf, &opts); + reftable_writer_set_limits(w, min, max); + + for (i = 0; i < n; i++) { + uint64_t before = refs[i].update_index; + int n = reftable_writer_add_ref(w, &refs[i]); + EXPECT(n == 0); + EXPECT(before == refs[i].update_index); + } + + err = reftable_writer_close(w); + EXPECT_ERR(err); + + reftable_writer_free(w); +} + +static struct reftable_merged_table * +merged_table_from_records(struct reftable_ref_record **refs, + struct reftable_block_source **source, + struct reftable_reader ***readers, int *sizes, + struct strbuf *buf, int n) +{ + int i = 0; + struct reftable_merged_table *mt = NULL; + int err; + struct reftable_table *tabs = + reftable_calloc(n * sizeof(struct reftable_table)); + *readers = reftable_calloc(n * sizeof(struct reftable_reader *)); + *source = reftable_calloc(n * sizeof(**source)); + for (i = 0; i < n; i++) { + write_test_table(&buf[i], refs[i], sizes[i]); + block_source_from_strbuf(&(*source)[i], &buf[i]); + + err = reftable_new_reader(&(*readers)[i], &(*source)[i], + "name"); + EXPECT_ERR(err); + reftable_table_from_reader(&tabs[i], (*readers)[i]); + } + + err = reftable_new_merged_table(&mt, tabs, n, GIT_SHA1_FORMAT_ID); + EXPECT_ERR(err); + return mt; +} + +static void readers_destroy(struct reftable_reader **readers, size_t n) +{ + int i = 0; + for (; i < n; i++) + reftable_reader_free(readers[i]); + reftable_free(readers); +} + +static void test_merged_between(void) +{ + uint8_t hash1[GIT_SHA1_RAWSZ] = { 1, 2, 3, 0 }; + + struct reftable_ref_record r1[] = { { + .refname = "b", + .update_index = 1, + .value_type = REFTABLE_REF_VAL1, + .value.val1 = hash1, + } }; + struct reftable_ref_record r2[] = { { + .refname = "a", + .update_index = 2, + .value_type = REFTABLE_REF_DELETION, + } }; + + struct reftable_ref_record *refs[] = { r1, r2 }; + int sizes[] = { 1, 1 }; + struct strbuf bufs[2] = { STRBUF_INIT, STRBUF_INIT }; + struct reftable_block_source *bs = NULL; + struct reftable_reader **readers = NULL; + struct reftable_merged_table *mt = + merged_table_from_records(refs, &bs, &readers, sizes, bufs, 2); + int i; + struct reftable_ref_record ref = { NULL }; + struct reftable_iterator it = { NULL }; + int err = reftable_merged_table_seek_ref(mt, &it, "a"); + EXPECT_ERR(err); + + err = reftable_iterator_next_ref(&it, &ref); + EXPECT_ERR(err); + EXPECT(ref.update_index == 2); + reftable_ref_record_release(&ref); + reftable_iterator_destroy(&it); + readers_destroy(readers, 2); + reftable_merged_table_free(mt); + for (i = 0; i < ARRAY_SIZE(bufs); i++) { + strbuf_release(&bufs[i]); + } + reftable_free(bs); +} + +static void test_merged(void) +{ + uint8_t hash1[GIT_SHA1_RAWSZ] = { 1 }; + uint8_t hash2[GIT_SHA1_RAWSZ] = { 2 }; + struct reftable_ref_record r1[] = { + { + .refname = "a", + .update_index = 1, + .value_type = REFTABLE_REF_VAL1, + .value.val1 = hash1, + }, + { + .refname = "b", + .update_index = 1, + .value_type = REFTABLE_REF_VAL1, + .value.val1 = hash1, + }, + { + .refname = "c", + .update_index = 1, + .value_type = REFTABLE_REF_VAL1, + .value.val1 = hash1, + } + }; + struct reftable_ref_record r2[] = { { + .refname = "a", + .update_index = 2, + .value_type = REFTABLE_REF_DELETION, + } }; + struct reftable_ref_record r3[] = { + { + .refname = "c", + .update_index = 3, + .value_type = REFTABLE_REF_VAL1, + .value.val1 = hash2, + }, + { + .refname = "d", + .update_index = 3, + .value_type = REFTABLE_REF_VAL1, + .value.val1 = hash1, + }, + }; + + struct reftable_ref_record want[] = { + r2[0], + r1[1], + r3[0], + r3[1], + }; + + struct reftable_ref_record *refs[] = { r1, r2, r3 }; + int sizes[3] = { 3, 1, 2 }; + struct strbuf bufs[3] = { STRBUF_INIT, STRBUF_INIT, STRBUF_INIT }; + struct reftable_block_source *bs = NULL; + struct reftable_reader **readers = NULL; + struct reftable_merged_table *mt = + merged_table_from_records(refs, &bs, &readers, sizes, bufs, 3); + + struct reftable_iterator it = { NULL }; + int err = reftable_merged_table_seek_ref(mt, &it, "a"); + struct reftable_ref_record *out = NULL; + size_t len = 0; + size_t cap = 0; + int i = 0; + + EXPECT_ERR(err); + while (len < 100) { /* cap loops/recursion. */ + struct reftable_ref_record ref = { NULL }; + int err = reftable_iterator_next_ref(&it, &ref); + if (err > 0) { + break; + } + if (len == cap) { + cap = 2 * cap + 1; + out = reftable_realloc( + out, sizeof(struct reftable_ref_record) * cap); + } + out[len++] = ref; + } + reftable_iterator_destroy(&it); + + EXPECT(ARRAY_SIZE(want) == len); + for (i = 0; i < len; i++) { + EXPECT(reftable_ref_record_equal(&want[i], &out[i], + GIT_SHA1_RAWSZ)); + } + for (i = 0; i < len; i++) { + reftable_ref_record_release(&out[i]); + } + reftable_free(out); + + for (i = 0; i < 3; i++) { + strbuf_release(&bufs[i]); + } + readers_destroy(readers, 3); + reftable_merged_table_free(mt); + reftable_free(bs); +} + +static void test_default_write_opts(void) +{ + struct reftable_write_options opts = { 0 }; + struct strbuf buf = STRBUF_INIT; + struct reftable_writer *w = + reftable_new_writer(&strbuf_add_void, &buf, &opts); + + struct reftable_ref_record rec = { + .refname = "master", + .update_index = 1, + }; + int err; + struct reftable_block_source source = { NULL }; + struct reftable_table *tab = reftable_calloc(sizeof(*tab) * 1); + uint32_t hash_id; + struct reftable_reader *rd = NULL; + struct reftable_merged_table *merged = NULL; + + reftable_writer_set_limits(w, 1, 1); + + err = reftable_writer_add_ref(w, &rec); + EXPECT_ERR(err); + + err = reftable_writer_close(w); + EXPECT_ERR(err); + reftable_writer_free(w); + + block_source_from_strbuf(&source, &buf); + + err = reftable_new_reader(&rd, &source, "filename"); + EXPECT_ERR(err); + + hash_id = reftable_reader_hash_id(rd); + EXPECT(hash_id == GIT_SHA1_FORMAT_ID); + + reftable_table_from_reader(&tab[0], rd); + err = reftable_new_merged_table(&merged, tab, 1, GIT_SHA1_FORMAT_ID); + EXPECT_ERR(err); + + reftable_reader_free(rd); + reftable_merged_table_free(merged); + strbuf_release(&buf); +} + +/* XXX test refs_for(oid) */ + +int merged_test_main(int argc, const char *argv[]) +{ + RUN_TEST(test_merged_between); + RUN_TEST(test_merged); + RUN_TEST(test_default_write_opts); + return 0; +} diff --git a/reftable/reftable-merged.h b/reftable/reftable-merged.h new file mode 100644 index 00000000000..1a6d16915ab --- /dev/null +++ b/reftable/reftable-merged.h @@ -0,0 +1,72 @@ +/* +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 +*/ + +#ifndef REFTABLE_MERGED_H +#define REFTABLE_MERGED_H + +#include "reftable-iterator.h" + +/* + * Merged tables + * + * A ref database kept in a sequence of table files. The merged_table presents a + * unified view to reading (seeking, iterating) a sequence of immutable tables. + * + * The merged tables are on purpose kept disconnected from their actual storage + * (eg. files on disk), because it is useful to merge tables aren't files. For + * example, the per-workspace and global ref namespace can be implemented as a + * merged table of two stacks of file-backed reftables. + */ + +/* A merged table is implements seeking/iterating over a stack of tables. */ +struct reftable_merged_table; + +/* A generic reftable; see below. */ +struct reftable_table; + +/* reftable_new_merged_table creates a new merged table. It takes ownership of + the stack array. +*/ +int reftable_new_merged_table(struct reftable_merged_table **dest, + struct reftable_table *stack, int n, + uint32_t hash_id); + +/* returns an iterator positioned just before 'name' */ +int reftable_merged_table_seek_ref(struct reftable_merged_table *mt, + struct reftable_iterator *it, + const char *name); + +/* returns an iterator for log entry, at given update_index */ +int reftable_merged_table_seek_log_at(struct reftable_merged_table *mt, + struct reftable_iterator *it, + const char *name, uint64_t update_index); + +/* like reftable_merged_table_seek_log_at but look for the newest entry. */ +int reftable_merged_table_seek_log(struct reftable_merged_table *mt, + struct reftable_iterator *it, + const char *name); + +/* returns the max update_index covered by this merged table. */ +uint64_t +reftable_merged_table_max_update_index(struct reftable_merged_table *mt); + +/* returns the min update_index covered by this merged table. */ +uint64_t +reftable_merged_table_min_update_index(struct reftable_merged_table *mt); + +/* releases memory for the merged_table */ +void reftable_merged_table_free(struct reftable_merged_table *m); + +/* return the hash ID of the merged table. */ +uint32_t reftable_merged_table_hash_id(struct reftable_merged_table *m); + +/* create a generic table from reftable_merged_table */ +void reftable_table_from_merged_table(struct reftable_table *tab, + struct reftable_merged_table *table); + +#endif diff --git a/t/helper/test-reftable.c b/t/helper/test-reftable.c index 0b5a1701df1..8087f2da4e6 100644 --- a/t/helper/test-reftable.c +++ b/t/helper/test-reftable.c @@ -5,6 +5,7 @@ int cmd__reftable(int argc, const char **argv) { basics_test_main(argc, argv); block_test_main(argc, argv); + merged_test_main(argc, argv); pq_test_main(argc, argv); record_test_main(argc, argv); readwrite_test_main(argc, argv);
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