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git/bulk-checkin.c
Jeff King 4a7e27e957 convert "oidcmp() == 0" to oideq()
Using the more restrictive oideq() should, in the long run,
give the compiler more opportunities to optimize these
callsites. For now, this conversion should be a complete
noop with respect to the generated code.

The result is also perhaps a little more readable, as it
avoids the "zero is equal" idiom. Since it's so prevalent in
C, I think seasoned programmers tend not to even notice it
anymore, but it can sometimes make for awkward double
negations (e.g., we can drop a few !!oidcmp() instances
here).

This patch was generated almost entirely by the included
coccinelle patch. This mechanical conversion should be
completely safe, because we check explicitly for cases where
oidcmp() is compared to 0, which is what oideq() is doing
under the hood. Note that we don't have to catch "!oidcmp()"
separately; coccinelle's standard isomorphisms make sure the
two are treated equivalently.

I say "almost" because I did hand-edit the coccinelle output
to fix up a few style violations (it mostly keeps the
original formatting, but sometimes unwraps long lines).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-29 11:32:49 -07:00

281 lines
7.3 KiB
C

/*
* Copyright (c) 2011, Google Inc.
*/
#include "cache.h"
#include "bulk-checkin.h"
#include "repository.h"
#include "csum-file.h"
#include "pack.h"
#include "strbuf.h"
#include "packfile.h"
#include "object-store.h"
static struct bulk_checkin_state {
unsigned plugged:1;
char *pack_tmp_name;
struct hashfile *f;
off_t offset;
struct pack_idx_option pack_idx_opts;
struct pack_idx_entry **written;
uint32_t alloc_written;
uint32_t nr_written;
} state;
static void finish_bulk_checkin(struct bulk_checkin_state *state)
{
struct object_id oid;
struct strbuf packname = STRBUF_INIT;
int i;
if (!state->f)
return;
if (state->nr_written == 0) {
close(state->f->fd);
unlink(state->pack_tmp_name);
goto clear_exit;
} else if (state->nr_written == 1) {
finalize_hashfile(state->f, oid.hash, CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE);
} else {
int fd = finalize_hashfile(state->f, oid.hash, 0);
fixup_pack_header_footer(fd, oid.hash, state->pack_tmp_name,
state->nr_written, oid.hash,
state->offset);
close(fd);
}
strbuf_addf(&packname, "%s/pack/pack-", get_object_directory());
finish_tmp_packfile(&packname, state->pack_tmp_name,
state->written, state->nr_written,
&state->pack_idx_opts, oid.hash);
for (i = 0; i < state->nr_written; i++)
free(state->written[i]);
clear_exit:
free(state->written);
memset(state, 0, sizeof(*state));
strbuf_release(&packname);
/* Make objects we just wrote available to ourselves */
reprepare_packed_git(the_repository);
}
static int already_written(struct bulk_checkin_state *state, struct object_id *oid)
{
int i;
/* The object may already exist in the repository */
if (has_sha1_file(oid->hash))
return 1;
/* Might want to keep the list sorted */
for (i = 0; i < state->nr_written; i++)
if (oideq(&state->written[i]->oid, oid))
return 1;
/* This is a new object we need to keep */
return 0;
}
/*
* Read the contents from fd for size bytes, streaming it to the
* packfile in state while updating the hash in ctx. Signal a failure
* by returning a negative value when the resulting pack would exceed
* the pack size limit and this is not the first object in the pack,
* so that the caller can discard what we wrote from the current pack
* by truncating it and opening a new one. The caller will then call
* us again after rewinding the input fd.
*
* The already_hashed_to pointer is kept untouched by the caller to
* make sure we do not hash the same byte when we are called
* again. This way, the caller does not have to checkpoint its hash
* status before calling us just in case we ask it to call us again
* with a new pack.
*/
static int stream_to_pack(struct bulk_checkin_state *state,
git_hash_ctx *ctx, off_t *already_hashed_to,
int fd, size_t size, enum object_type type,
const char *path, unsigned flags)
{
git_zstream s;
unsigned char obuf[16384];
unsigned hdrlen;
int status = Z_OK;
int write_object = (flags & HASH_WRITE_OBJECT);
off_t offset = 0;
git_deflate_init(&s, pack_compression_level);
hdrlen = encode_in_pack_object_header(obuf, sizeof(obuf), type, size);
s.next_out = obuf + hdrlen;
s.avail_out = sizeof(obuf) - hdrlen;
while (status != Z_STREAM_END) {
unsigned char ibuf[16384];
if (size && !s.avail_in) {
ssize_t rsize = size < sizeof(ibuf) ? size : sizeof(ibuf);
ssize_t read_result = read_in_full(fd, ibuf, rsize);
if (read_result < 0)
die_errno("failed to read from '%s'", path);
if (read_result != rsize)
die("failed to read %d bytes from '%s'",
(int)rsize, path);
offset += rsize;
if (*already_hashed_to < offset) {
size_t hsize = offset - *already_hashed_to;
if (rsize < hsize)
hsize = rsize;
if (hsize)
the_hash_algo->update_fn(ctx, ibuf, hsize);
*already_hashed_to = offset;
}
s.next_in = ibuf;
s.avail_in = rsize;
size -= rsize;
}
status = git_deflate(&s, size ? 0 : Z_FINISH);
if (!s.avail_out || status == Z_STREAM_END) {
if (write_object) {
size_t written = s.next_out - obuf;
/* would we bust the size limit? */
if (state->nr_written &&
pack_size_limit_cfg &&
pack_size_limit_cfg < state->offset + written) {
git_deflate_abort(&s);
return -1;
}
hashwrite(state->f, obuf, written);
state->offset += written;
}
s.next_out = obuf;
s.avail_out = sizeof(obuf);
}
switch (status) {
case Z_OK:
case Z_BUF_ERROR:
case Z_STREAM_END:
continue;
default:
die("unexpected deflate failure: %d", status);
}
}
git_deflate_end(&s);
return 0;
}
/* Lazily create backing packfile for the state */
static void prepare_to_stream(struct bulk_checkin_state *state,
unsigned flags)
{
if (!(flags & HASH_WRITE_OBJECT) || state->f)
return;
state->f = create_tmp_packfile(&state->pack_tmp_name);
reset_pack_idx_option(&state->pack_idx_opts);
/* Pretend we are going to write only one object */
state->offset = write_pack_header(state->f, 1);
if (!state->offset)
die_errno("unable to write pack header");
}
static int deflate_to_pack(struct bulk_checkin_state *state,
struct object_id *result_oid,
int fd, size_t size,
enum object_type type, const char *path,
unsigned flags)
{
off_t seekback, already_hashed_to;
git_hash_ctx ctx;
unsigned char obuf[16384];
unsigned header_len;
struct hashfile_checkpoint checkpoint;
struct pack_idx_entry *idx = NULL;
seekback = lseek(fd, 0, SEEK_CUR);
if (seekback == (off_t) -1)
return error("cannot find the current offset");
header_len = xsnprintf((char *)obuf, sizeof(obuf), "%s %" PRIuMAX,
type_name(type), (uintmax_t)size) + 1;
the_hash_algo->init_fn(&ctx);
the_hash_algo->update_fn(&ctx, obuf, header_len);
/* Note: idx is non-NULL when we are writing */
if ((flags & HASH_WRITE_OBJECT) != 0)
idx = xcalloc(1, sizeof(*idx));
already_hashed_to = 0;
while (1) {
prepare_to_stream(state, flags);
if (idx) {
hashfile_checkpoint(state->f, &checkpoint);
idx->offset = state->offset;
crc32_begin(state->f);
}
if (!stream_to_pack(state, &ctx, &already_hashed_to,
fd, size, type, path, flags))
break;
/*
* Writing this object to the current pack will make
* it too big; we need to truncate it, start a new
* pack, and write into it.
*/
if (!idx)
BUG("should not happen");
hashfile_truncate(state->f, &checkpoint);
state->offset = checkpoint.offset;
finish_bulk_checkin(state);
if (lseek(fd, seekback, SEEK_SET) == (off_t) -1)
return error("cannot seek back");
}
the_hash_algo->final_fn(result_oid->hash, &ctx);
if (!idx)
return 0;
idx->crc32 = crc32_end(state->f);
if (already_written(state, result_oid)) {
hashfile_truncate(state->f, &checkpoint);
state->offset = checkpoint.offset;
free(idx);
} else {
oidcpy(&idx->oid, result_oid);
ALLOC_GROW(state->written,
state->nr_written + 1,
state->alloc_written);
state->written[state->nr_written++] = idx;
}
return 0;
}
int index_bulk_checkin(struct object_id *oid,
int fd, size_t size, enum object_type type,
const char *path, unsigned flags)
{
int status = deflate_to_pack(&state, oid, fd, size, type,
path, flags);
if (!state.plugged)
finish_bulk_checkin(&state);
return status;
}
void plug_bulk_checkin(void)
{
state.plugged = 1;
}
void unplug_bulk_checkin(void)
{
state.plugged = 0;
if (state.f)
finish_bulk_checkin(&state);
}