reftable: write reftable files

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Han-Wen Nienhuys 2021-10-07 20:25:06 +00:00 коммит произвёл Junio C Hamano
Родитель 35425d1034
Коммит f14bd71934
4 изменённых файлов: 889 добавлений и 0 удалений

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@ -2463,6 +2463,7 @@ REFTABLE_OBJS += reftable/blocksource.o
REFTABLE_OBJS += reftable/publicbasics.o
REFTABLE_OBJS += reftable/record.o
REFTABLE_OBJS += reftable/tree.o
REFTABLE_OBJS += reftable/writer.o
REFTABLE_TEST_OBJS += reftable/basics_test.o
REFTABLE_TEST_OBJS += reftable/block_test.o

148
reftable/reftable-writer.h Normal file
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@ -0,0 +1,148 @@
/*
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_WRITER_H
#define REFTABLE_WRITER_H
#include "reftable-record.h"
#include <stdint.h>
#include <unistd.h> /* ssize_t */
/* Writing single reftables */
/* reftable_write_options sets options for writing a single reftable. */
struct reftable_write_options {
/* boolean: do not pad out blocks to block size. */
unsigned unpadded : 1;
/* the blocksize. Should be less than 2^24. */
uint32_t block_size;
/* boolean: do not generate a SHA1 => ref index. */
unsigned skip_index_objects : 1;
/* how often to write complete keys in each block. */
int restart_interval;
/* 4-byte identifier ("sha1", "s256") of the hash.
* Defaults to SHA1 if unset
*/
uint32_t hash_id;
/* boolean: do not check ref names for validity or dir/file conflicts.
*/
unsigned skip_name_check : 1;
/* boolean: copy log messages exactly. If unset, check that the message
* is a single line, and add '\n' if missing.
*/
unsigned exact_log_message : 1;
};
/* reftable_block_stats holds statistics for a single block type */
struct reftable_block_stats {
/* total number of entries written */
int entries;
/* total number of key restarts */
int restarts;
/* total number of blocks */
int blocks;
/* total number of index blocks */
int index_blocks;
/* depth of the index */
int max_index_level;
/* offset of the first block for this type */
uint64_t offset;
/* offset of the top level index block for this type, or 0 if not
* present */
uint64_t index_offset;
};
/* stats holds overall statistics for a single reftable */
struct reftable_stats {
/* total number of blocks written. */
int blocks;
/* stats for ref data */
struct reftable_block_stats ref_stats;
/* stats for the SHA1 to ref map. */
struct reftable_block_stats obj_stats;
/* stats for index blocks */
struct reftable_block_stats idx_stats;
/* stats for log blocks */
struct reftable_block_stats log_stats;
/* disambiguation length of shortened object IDs. */
int object_id_len;
};
/* reftable_new_writer creates a new writer */
struct reftable_writer *
reftable_new_writer(ssize_t (*writer_func)(void *, const void *, size_t),
void *writer_arg, struct reftable_write_options *opts);
/* Set the range of update indices for the records we will add. When writing a
table into a stack, the min should be at least
reftable_stack_next_update_index(), or REFTABLE_API_ERROR is returned.
For transactional updates to a stack, typically min==max, and the
update_index can be obtained by inspeciting the stack. When converting an
existing ref database into a single reftable, this would be a range of
update-index timestamps.
*/
void reftable_writer_set_limits(struct reftable_writer *w, uint64_t min,
uint64_t max);
/*
Add a reftable_ref_record. The record should have names that come after
already added records.
The update_index must be within the limits set by
reftable_writer_set_limits(), or REFTABLE_API_ERROR is returned. It is an
REFTABLE_API_ERROR error to write a ref record after a log record.
*/
int reftable_writer_add_ref(struct reftable_writer *w,
struct reftable_ref_record *ref);
/*
Convenience function to add multiple reftable_ref_records; the function sorts
the records before adding them, reordering the records array passed in.
*/
int reftable_writer_add_refs(struct reftable_writer *w,
struct reftable_ref_record *refs, int n);
/*
adds reftable_log_records. Log records are keyed by (refname, decreasing
update_index). The key for the record added must come after the already added
log records.
*/
int reftable_writer_add_log(struct reftable_writer *w,
struct reftable_log_record *log);
/*
Convenience function to add multiple reftable_log_records; the function sorts
the records before adding them, reordering records array passed in.
*/
int reftable_writer_add_logs(struct reftable_writer *w,
struct reftable_log_record *logs, int n);
/* reftable_writer_close finalizes the reftable. The writer is retained so
* statistics can be inspected. */
int reftable_writer_close(struct reftable_writer *w);
/* writer_stats returns the statistics on the reftable being written.
This struct becomes invalid when the writer is freed.
*/
const struct reftable_stats *writer_stats(struct reftable_writer *w);
/* reftable_writer_free deallocates memory for the writer */
void reftable_writer_free(struct reftable_writer *w);
#endif

690
reftable/writer.c Normal file
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/*
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 "writer.h"
#include "system.h"
#include "block.h"
#include "constants.h"
#include "record.h"
#include "tree.h"
#include "reftable-error.h"
/* finishes a block, and writes it to storage */
static int writer_flush_block(struct reftable_writer *w);
/* deallocates memory related to the index */
static void writer_clear_index(struct reftable_writer *w);
/* finishes writing a 'r' (refs) or 'g' (reflogs) section */
static int writer_finish_public_section(struct reftable_writer *w);
static struct reftable_block_stats *
writer_reftable_block_stats(struct reftable_writer *w, uint8_t typ)
{
switch (typ) {
case 'r':
return &w->stats.ref_stats;
case 'o':
return &w->stats.obj_stats;
case 'i':
return &w->stats.idx_stats;
case 'g':
return &w->stats.log_stats;
}
abort();
return NULL;
}
/* write data, queuing the padding for the next write. Returns negative for
* error. */
static int padded_write(struct reftable_writer *w, uint8_t *data, size_t len,
int padding)
{
int n = 0;
if (w->pending_padding > 0) {
uint8_t *zeroed = reftable_calloc(w->pending_padding);
int n = w->write(w->write_arg, zeroed, w->pending_padding);
if (n < 0)
return n;
w->pending_padding = 0;
reftable_free(zeroed);
}
w->pending_padding = padding;
n = w->write(w->write_arg, data, len);
if (n < 0)
return n;
n += padding;
return 0;
}
static void options_set_defaults(struct reftable_write_options *opts)
{
if (opts->restart_interval == 0) {
opts->restart_interval = 16;
}
if (opts->hash_id == 0) {
opts->hash_id = GIT_SHA1_FORMAT_ID;
}
if (opts->block_size == 0) {
opts->block_size = DEFAULT_BLOCK_SIZE;
}
}
static int writer_version(struct reftable_writer *w)
{
return (w->opts.hash_id == 0 || w->opts.hash_id == GIT_SHA1_FORMAT_ID) ?
1 :
2;
}
static int writer_write_header(struct reftable_writer *w, uint8_t *dest)
{
memcpy(dest, "REFT", 4);
dest[4] = writer_version(w);
put_be24(dest + 5, w->opts.block_size);
put_be64(dest + 8, w->min_update_index);
put_be64(dest + 16, w->max_update_index);
if (writer_version(w) == 2) {
put_be32(dest + 24, w->opts.hash_id);
}
return header_size(writer_version(w));
}
static void writer_reinit_block_writer(struct reftable_writer *w, uint8_t typ)
{
int block_start = 0;
if (w->next == 0) {
block_start = header_size(writer_version(w));
}
strbuf_release(&w->last_key);
block_writer_init(&w->block_writer_data, typ, w->block,
w->opts.block_size, block_start,
hash_size(w->opts.hash_id));
w->block_writer = &w->block_writer_data;
w->block_writer->restart_interval = w->opts.restart_interval;
}
static struct strbuf reftable_empty_strbuf = STRBUF_INIT;
struct reftable_writer *
reftable_new_writer(ssize_t (*writer_func)(void *, const void *, size_t),
void *writer_arg, struct reftable_write_options *opts)
{
struct reftable_writer *wp =
reftable_calloc(sizeof(struct reftable_writer));
strbuf_init(&wp->block_writer_data.last_key, 0);
options_set_defaults(opts);
if (opts->block_size >= (1 << 24)) {
/* TODO - error return? */
abort();
}
wp->last_key = reftable_empty_strbuf;
wp->block = reftable_calloc(opts->block_size);
wp->write = writer_func;
wp->write_arg = writer_arg;
wp->opts = *opts;
writer_reinit_block_writer(wp, BLOCK_TYPE_REF);
return wp;
}
void reftable_writer_set_limits(struct reftable_writer *w, uint64_t min,
uint64_t max)
{
w->min_update_index = min;
w->max_update_index = max;
}
void reftable_writer_free(struct reftable_writer *w)
{
reftable_free(w->block);
reftable_free(w);
}
struct obj_index_tree_node {
struct strbuf hash;
uint64_t *offsets;
size_t offset_len;
size_t offset_cap;
};
#define OBJ_INDEX_TREE_NODE_INIT \
{ \
.hash = STRBUF_INIT \
}
static int obj_index_tree_node_compare(const void *a, const void *b)
{
return strbuf_cmp(&((const struct obj_index_tree_node *)a)->hash,
&((const struct obj_index_tree_node *)b)->hash);
}
static void writer_index_hash(struct reftable_writer *w, struct strbuf *hash)
{
uint64_t off = w->next;
struct obj_index_tree_node want = { .hash = *hash };
struct tree_node *node = tree_search(&want, &w->obj_index_tree,
&obj_index_tree_node_compare, 0);
struct obj_index_tree_node *key = NULL;
if (node == NULL) {
struct obj_index_tree_node empty = OBJ_INDEX_TREE_NODE_INIT;
key = reftable_malloc(sizeof(struct obj_index_tree_node));
*key = empty;
strbuf_reset(&key->hash);
strbuf_addbuf(&key->hash, hash);
tree_search((void *)key, &w->obj_index_tree,
&obj_index_tree_node_compare, 1);
} else {
key = node->key;
}
if (key->offset_len > 0 && key->offsets[key->offset_len - 1] == off) {
return;
}
if (key->offset_len == key->offset_cap) {
key->offset_cap = 2 * key->offset_cap + 1;
key->offsets = reftable_realloc(
key->offsets, sizeof(uint64_t) * key->offset_cap);
}
key->offsets[key->offset_len++] = off;
}
static int writer_add_record(struct reftable_writer *w,
struct reftable_record *rec)
{
struct strbuf key = STRBUF_INIT;
int err = -1;
reftable_record_key(rec, &key);
if (strbuf_cmp(&w->last_key, &key) >= 0) {
err = REFTABLE_API_ERROR;
goto done;
}
strbuf_reset(&w->last_key);
strbuf_addbuf(&w->last_key, &key);
if (w->block_writer == NULL) {
writer_reinit_block_writer(w, reftable_record_type(rec));
}
assert(block_writer_type(w->block_writer) == reftable_record_type(rec));
if (block_writer_add(w->block_writer, rec) == 0) {
err = 0;
goto done;
}
err = writer_flush_block(w);
if (err < 0) {
goto done;
}
writer_reinit_block_writer(w, reftable_record_type(rec));
err = block_writer_add(w->block_writer, rec);
if (err < 0) {
goto done;
}
err = 0;
done:
strbuf_release(&key);
return err;
}
int reftable_writer_add_ref(struct reftable_writer *w,
struct reftable_ref_record *ref)
{
struct reftable_record rec = { NULL };
struct reftable_ref_record copy = *ref;
int err = 0;
if (ref->refname == NULL)
return REFTABLE_API_ERROR;
if (ref->update_index < w->min_update_index ||
ref->update_index > w->max_update_index)
return REFTABLE_API_ERROR;
reftable_record_from_ref(&rec, &copy);
copy.update_index -= w->min_update_index;
err = writer_add_record(w, &rec);
if (err < 0)
return err;
if (!w->opts.skip_index_objects && reftable_ref_record_val1(ref)) {
struct strbuf h = STRBUF_INIT;
strbuf_add(&h, (char *)reftable_ref_record_val1(ref),
hash_size(w->opts.hash_id));
writer_index_hash(w, &h);
strbuf_release(&h);
}
if (!w->opts.skip_index_objects && reftable_ref_record_val2(ref)) {
struct strbuf h = STRBUF_INIT;
strbuf_add(&h, reftable_ref_record_val2(ref),
hash_size(w->opts.hash_id));
writer_index_hash(w, &h);
strbuf_release(&h);
}
return 0;
}
int reftable_writer_add_refs(struct reftable_writer *w,
struct reftable_ref_record *refs, int n)
{
int err = 0;
int i = 0;
QSORT(refs, n, reftable_ref_record_compare_name);
for (i = 0; err == 0 && i < n; i++) {
err = reftable_writer_add_ref(w, &refs[i]);
}
return err;
}
static int reftable_writer_add_log_verbatim(struct reftable_writer *w,
struct reftable_log_record *log)
{
struct reftable_record rec = { NULL };
if (w->block_writer &&
block_writer_type(w->block_writer) == BLOCK_TYPE_REF) {
int err = writer_finish_public_section(w);
if (err < 0)
return err;
}
w->next -= w->pending_padding;
w->pending_padding = 0;
reftable_record_from_log(&rec, log);
return writer_add_record(w, &rec);
}
int reftable_writer_add_log(struct reftable_writer *w,
struct reftable_log_record *log)
{
char *input_log_message = NULL;
struct strbuf cleaned_message = STRBUF_INIT;
int err = 0;
if (log->value_type == REFTABLE_LOG_DELETION)
return reftable_writer_add_log_verbatim(w, log);
if (log->refname == NULL)
return REFTABLE_API_ERROR;
input_log_message = log->value.update.message;
if (!w->opts.exact_log_message && log->value.update.message) {
strbuf_addstr(&cleaned_message, log->value.update.message);
while (cleaned_message.len &&
cleaned_message.buf[cleaned_message.len - 1] == '\n')
strbuf_setlen(&cleaned_message,
cleaned_message.len - 1);
if (strchr(cleaned_message.buf, '\n')) {
/* multiple lines not allowed. */
err = REFTABLE_API_ERROR;
goto done;
}
strbuf_addstr(&cleaned_message, "\n");
log->value.update.message = cleaned_message.buf;
}
err = reftable_writer_add_log_verbatim(w, log);
log->value.update.message = input_log_message;
done:
strbuf_release(&cleaned_message);
return err;
}
int reftable_writer_add_logs(struct reftable_writer *w,
struct reftable_log_record *logs, int n)
{
int err = 0;
int i = 0;
QSORT(logs, n, reftable_log_record_compare_key);
for (i = 0; err == 0 && i < n; i++) {
err = reftable_writer_add_log(w, &logs[i]);
}
return err;
}
static int writer_finish_section(struct reftable_writer *w)
{
uint8_t typ = block_writer_type(w->block_writer);
uint64_t index_start = 0;
int max_level = 0;
int threshold = w->opts.unpadded ? 1 : 3;
int before_blocks = w->stats.idx_stats.blocks;
int err = writer_flush_block(w);
int i = 0;
struct reftable_block_stats *bstats = NULL;
if (err < 0)
return err;
while (w->index_len > threshold) {
struct reftable_index_record *idx = NULL;
int idx_len = 0;
max_level++;
index_start = w->next;
writer_reinit_block_writer(w, BLOCK_TYPE_INDEX);
idx = w->index;
idx_len = w->index_len;
w->index = NULL;
w->index_len = 0;
w->index_cap = 0;
for (i = 0; i < idx_len; i++) {
struct reftable_record rec = { NULL };
reftable_record_from_index(&rec, idx + i);
if (block_writer_add(w->block_writer, &rec) == 0) {
continue;
}
err = writer_flush_block(w);
if (err < 0)
return err;
writer_reinit_block_writer(w, BLOCK_TYPE_INDEX);
err = block_writer_add(w->block_writer, &rec);
if (err != 0) {
/* write into fresh block should always succeed
*/
abort();
}
}
for (i = 0; i < idx_len; i++) {
strbuf_release(&idx[i].last_key);
}
reftable_free(idx);
}
writer_clear_index(w);
err = writer_flush_block(w);
if (err < 0)
return err;
bstats = writer_reftable_block_stats(w, typ);
bstats->index_blocks = w->stats.idx_stats.blocks - before_blocks;
bstats->index_offset = index_start;
bstats->max_index_level = max_level;
/* Reinit lastKey, as the next section can start with any key. */
w->last_key.len = 0;
return 0;
}
struct common_prefix_arg {
struct strbuf *last;
int max;
};
static void update_common(void *void_arg, void *key)
{
struct common_prefix_arg *arg = void_arg;
struct obj_index_tree_node *entry = key;
if (arg->last) {
int n = common_prefix_size(&entry->hash, arg->last);
if (n > arg->max) {
arg->max = n;
}
}
arg->last = &entry->hash;
}
struct write_record_arg {
struct reftable_writer *w;
int err;
};
static void write_object_record(void *void_arg, void *key)
{
struct write_record_arg *arg = void_arg;
struct obj_index_tree_node *entry = key;
struct reftable_obj_record obj_rec = {
.hash_prefix = (uint8_t *)entry->hash.buf,
.hash_prefix_len = arg->w->stats.object_id_len,
.offsets = entry->offsets,
.offset_len = entry->offset_len,
};
struct reftable_record rec = { NULL };
if (arg->err < 0)
goto done;
reftable_record_from_obj(&rec, &obj_rec);
arg->err = block_writer_add(arg->w->block_writer, &rec);
if (arg->err == 0)
goto done;
arg->err = writer_flush_block(arg->w);
if (arg->err < 0)
goto done;
writer_reinit_block_writer(arg->w, BLOCK_TYPE_OBJ);
arg->err = block_writer_add(arg->w->block_writer, &rec);
if (arg->err == 0)
goto done;
obj_rec.offset_len = 0;
arg->err = block_writer_add(arg->w->block_writer, &rec);
/* Should be able to write into a fresh block. */
assert(arg->err == 0);
done:;
}
static void object_record_free(void *void_arg, void *key)
{
struct obj_index_tree_node *entry = key;
FREE_AND_NULL(entry->offsets);
strbuf_release(&entry->hash);
reftable_free(entry);
}
static int writer_dump_object_index(struct reftable_writer *w)
{
struct write_record_arg closure = { .w = w };
struct common_prefix_arg common = { NULL };
if (w->obj_index_tree) {
infix_walk(w->obj_index_tree, &update_common, &common);
}
w->stats.object_id_len = common.max + 1;
writer_reinit_block_writer(w, BLOCK_TYPE_OBJ);
if (w->obj_index_tree) {
infix_walk(w->obj_index_tree, &write_object_record, &closure);
}
if (closure.err < 0)
return closure.err;
return writer_finish_section(w);
}
static int writer_finish_public_section(struct reftable_writer *w)
{
uint8_t typ = 0;
int err = 0;
if (w->block_writer == NULL)
return 0;
typ = block_writer_type(w->block_writer);
err = writer_finish_section(w);
if (err < 0)
return err;
if (typ == BLOCK_TYPE_REF && !w->opts.skip_index_objects &&
w->stats.ref_stats.index_blocks > 0) {
err = writer_dump_object_index(w);
if (err < 0)
return err;
}
if (w->obj_index_tree) {
infix_walk(w->obj_index_tree, &object_record_free, NULL);
tree_free(w->obj_index_tree);
w->obj_index_tree = NULL;
}
w->block_writer = NULL;
return 0;
}
int reftable_writer_close(struct reftable_writer *w)
{
uint8_t footer[72];
uint8_t *p = footer;
int err = writer_finish_public_section(w);
int empty_table = w->next == 0;
if (err != 0)
goto done;
w->pending_padding = 0;
if (empty_table) {
/* Empty tables need a header anyway. */
uint8_t header[28];
int n = writer_write_header(w, header);
err = padded_write(w, header, n, 0);
if (err < 0)
goto done;
}
p += writer_write_header(w, footer);
put_be64(p, w->stats.ref_stats.index_offset);
p += 8;
put_be64(p, (w->stats.obj_stats.offset) << 5 | w->stats.object_id_len);
p += 8;
put_be64(p, w->stats.obj_stats.index_offset);
p += 8;
put_be64(p, w->stats.log_stats.offset);
p += 8;
put_be64(p, w->stats.log_stats.index_offset);
p += 8;
put_be32(p, crc32(0, footer, p - footer));
p += 4;
err = padded_write(w, footer, footer_size(writer_version(w)), 0);
if (err < 0)
goto done;
if (empty_table) {
err = REFTABLE_EMPTY_TABLE_ERROR;
goto done;
}
done:
/* free up memory. */
block_writer_release(&w->block_writer_data);
writer_clear_index(w);
strbuf_release(&w->last_key);
return err;
}
static void writer_clear_index(struct reftable_writer *w)
{
int i = 0;
for (i = 0; i < w->index_len; i++) {
strbuf_release(&w->index[i].last_key);
}
FREE_AND_NULL(w->index);
w->index_len = 0;
w->index_cap = 0;
}
static const int debug = 0;
static int writer_flush_nonempty_block(struct reftable_writer *w)
{
uint8_t typ = block_writer_type(w->block_writer);
struct reftable_block_stats *bstats =
writer_reftable_block_stats(w, typ);
uint64_t block_typ_off = (bstats->blocks == 0) ? w->next : 0;
int raw_bytes = block_writer_finish(w->block_writer);
int padding = 0;
int err = 0;
struct reftable_index_record ir = { .last_key = STRBUF_INIT };
if (raw_bytes < 0)
return raw_bytes;
if (!w->opts.unpadded && typ != BLOCK_TYPE_LOG) {
padding = w->opts.block_size - raw_bytes;
}
if (block_typ_off > 0) {
bstats->offset = block_typ_off;
}
bstats->entries += w->block_writer->entries;
bstats->restarts += w->block_writer->restart_len;
bstats->blocks++;
w->stats.blocks++;
if (debug) {
fprintf(stderr, "block %c off %" PRIu64 " sz %d (%d)\n", typ,
w->next, raw_bytes,
get_be24(w->block + w->block_writer->header_off + 1));
}
if (w->next == 0) {
writer_write_header(w, w->block);
}
err = padded_write(w, w->block, raw_bytes, padding);
if (err < 0)
return err;
if (w->index_cap == w->index_len) {
w->index_cap = 2 * w->index_cap + 1;
w->index = reftable_realloc(
w->index,
sizeof(struct reftable_index_record) * w->index_cap);
}
ir.offset = w->next;
strbuf_reset(&ir.last_key);
strbuf_addbuf(&ir.last_key, &w->block_writer->last_key);
w->index[w->index_len] = ir;
w->index_len++;
w->next += padding + raw_bytes;
w->block_writer = NULL;
return 0;
}
static int writer_flush_block(struct reftable_writer *w)
{
if (w->block_writer == NULL)
return 0;
if (w->block_writer->entries == 0)
return 0;
return writer_flush_nonempty_block(w);
}
const struct reftable_stats *writer_stats(struct reftable_writer *w)
{
return &w->stats;
}

50
reftable/writer.h Normal file
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/*
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 WRITER_H
#define WRITER_H
#include "basics.h"
#include "block.h"
#include "tree.h"
#include "reftable-writer.h"
struct reftable_writer {
ssize_t (*write)(void *, const void *, size_t);
void *write_arg;
int pending_padding;
struct strbuf last_key;
/* offset of next block to write. */
uint64_t next;
uint64_t min_update_index, max_update_index;
struct reftable_write_options opts;
/* memory buffer for writing */
uint8_t *block;
/* writer for the current section. NULL or points to
* block_writer_data */
struct block_writer *block_writer;
struct block_writer block_writer_data;
/* pending index records for the current section */
struct reftable_index_record *index;
size_t index_len;
size_t index_cap;
/*
* tree for use with tsearch; used to populate the 'o' inverse OID
* map */
struct tree_node *obj_index_tree;
struct reftable_stats stats;
};
#endif