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![Junio C Hamano](/assets/img/avatar_default.png)
This extends the earlier approach to stream a large file directly from the filesystem to its own packfile, and allows "git add" to send large files directly into a single pack. Older code used to spawn fast-import, but the new bulk-checkin API replaces it. Signed-off-by: Junio C Hamano <gitster@pobox.com>
276 lines
7 KiB
C
276 lines
7 KiB
C
/*
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* Copyright (c) 2011, Google Inc.
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*/
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#include "bulk-checkin.h"
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#include "csum-file.h"
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#include "pack.h"
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static int pack_compression_level = Z_DEFAULT_COMPRESSION;
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static struct bulk_checkin_state {
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unsigned plugged:1;
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char *pack_tmp_name;
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struct sha1file *f;
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off_t offset;
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struct pack_idx_option pack_idx_opts;
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struct pack_idx_entry **written;
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uint32_t alloc_written;
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uint32_t nr_written;
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} state;
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static void finish_bulk_checkin(struct bulk_checkin_state *state)
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{
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unsigned char sha1[20];
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char packname[PATH_MAX];
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int i;
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if (!state->f)
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return;
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if (state->nr_written == 0) {
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close(state->f->fd);
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unlink(state->pack_tmp_name);
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goto clear_exit;
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} else if (state->nr_written == 1) {
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sha1close(state->f, sha1, CSUM_FSYNC);
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} else {
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int fd = sha1close(state->f, sha1, 0);
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fixup_pack_header_footer(fd, sha1, state->pack_tmp_name,
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state->nr_written, sha1,
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state->offset);
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close(fd);
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}
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sprintf(packname, "%s/pack/pack-", get_object_directory());
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finish_tmp_packfile(packname, state->pack_tmp_name,
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state->written, state->nr_written,
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&state->pack_idx_opts, sha1);
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for (i = 0; i < state->nr_written; i++)
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free(state->written[i]);
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clear_exit:
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free(state->written);
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memset(state, 0, sizeof(*state));
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/* Make objects we just wrote available to ourselves */
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reprepare_packed_git();
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}
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static int already_written(struct bulk_checkin_state *state, unsigned char sha1[])
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{
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int i;
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/* The object may already exist in the repository */
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if (has_sha1_file(sha1))
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return 1;
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/* Might want to keep the list sorted */
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for (i = 0; i < state->nr_written; i++)
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if (!hashcmp(state->written[i]->sha1, sha1))
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return 1;
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/* This is a new object we need to keep */
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return 0;
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}
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/*
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* Read the contents from fd for size bytes, streaming it to the
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* packfile in state while updating the hash in ctx. Signal a failure
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* by returning a negative value when the resulting pack would exceed
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* the pack size limit and this is not the first object in the pack,
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* so that the caller can discard what we wrote from the current pack
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* by truncating it and opening a new one. The caller will then call
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* us again after rewinding the input fd.
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*
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* The already_hashed_to pointer is kept untouched by the caller to
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* make sure we do not hash the same byte when we are called
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* again. This way, the caller does not have to checkpoint its hash
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* status before calling us just in case we ask it to call us again
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* with a new pack.
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*/
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static int stream_to_pack(struct bulk_checkin_state *state,
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git_SHA_CTX *ctx, off_t *already_hashed_to,
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int fd, size_t size, enum object_type type,
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const char *path, unsigned flags)
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{
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git_zstream s;
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unsigned char obuf[16384];
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unsigned hdrlen;
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int status = Z_OK;
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int write_object = (flags & HASH_WRITE_OBJECT);
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off_t offset = 0;
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memset(&s, 0, sizeof(s));
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git_deflate_init(&s, pack_compression_level);
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hdrlen = encode_in_pack_object_header(type, size, obuf);
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s.next_out = obuf + hdrlen;
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s.avail_out = sizeof(obuf) - hdrlen;
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while (status != Z_STREAM_END) {
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unsigned char ibuf[16384];
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if (size && !s.avail_in) {
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ssize_t rsize = size < sizeof(ibuf) ? size : sizeof(ibuf);
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if (xread(fd, ibuf, rsize) != rsize)
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die("failed to read %d bytes from '%s'",
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(int)rsize, path);
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offset += rsize;
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if (*already_hashed_to < offset) {
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size_t hsize = offset - *already_hashed_to;
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if (rsize < hsize)
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hsize = rsize;
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if (hsize)
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git_SHA1_Update(ctx, ibuf, hsize);
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*already_hashed_to = offset;
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}
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s.next_in = ibuf;
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s.avail_in = rsize;
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size -= rsize;
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}
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status = git_deflate(&s, size ? 0 : Z_FINISH);
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if (!s.avail_out || status == Z_STREAM_END) {
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if (write_object) {
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size_t written = s.next_out - obuf;
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/* would we bust the size limit? */
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if (state->nr_written &&
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pack_size_limit_cfg &&
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pack_size_limit_cfg < state->offset + written) {
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git_deflate_abort(&s);
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return -1;
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}
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sha1write(state->f, obuf, written);
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state->offset += written;
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}
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s.next_out = obuf;
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s.avail_out = sizeof(obuf);
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}
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switch (status) {
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case Z_OK:
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case Z_BUF_ERROR:
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case Z_STREAM_END:
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continue;
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default:
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die("unexpected deflate failure: %d", status);
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}
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}
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git_deflate_end(&s);
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return 0;
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}
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/* Lazily create backing packfile for the state */
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static void prepare_to_stream(struct bulk_checkin_state *state,
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unsigned flags)
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{
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if (!(flags & HASH_WRITE_OBJECT) || state->f)
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return;
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state->f = create_tmp_packfile(&state->pack_tmp_name);
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reset_pack_idx_option(&state->pack_idx_opts);
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/* Pretend we are going to write only one object */
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state->offset = write_pack_header(state->f, 1);
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if (!state->offset)
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die_errno("unable to write pack header");
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}
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static int deflate_to_pack(struct bulk_checkin_state *state,
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unsigned char result_sha1[],
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int fd, size_t size,
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enum object_type type, const char *path,
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unsigned flags)
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{
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off_t seekback, already_hashed_to;
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git_SHA_CTX ctx;
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unsigned char obuf[16384];
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unsigned header_len;
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struct sha1file_checkpoint checkpoint;
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struct pack_idx_entry *idx = NULL;
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seekback = lseek(fd, 0, SEEK_CUR);
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if (seekback == (off_t) -1)
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return error("cannot find the current offset");
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header_len = sprintf((char *)obuf, "%s %" PRIuMAX,
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typename(type), (uintmax_t)size) + 1;
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git_SHA1_Init(&ctx);
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git_SHA1_Update(&ctx, obuf, header_len);
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/* Note: idx is non-NULL when we are writing */
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if ((flags & HASH_WRITE_OBJECT) != 0)
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idx = xcalloc(1, sizeof(*idx));
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already_hashed_to = 0;
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while (1) {
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prepare_to_stream(state, flags);
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if (idx) {
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sha1file_checkpoint(state->f, &checkpoint);
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idx->offset = state->offset;
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crc32_begin(state->f);
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}
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if (!stream_to_pack(state, &ctx, &already_hashed_to,
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fd, size, type, path, flags))
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break;
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/*
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* Writing this object to the current pack will make
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* it too big; we need to truncate it, start a new
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* pack, and write into it.
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*/
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if (!idx)
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die("BUG: should not happen");
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sha1file_truncate(state->f, &checkpoint);
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state->offset = checkpoint.offset;
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finish_bulk_checkin(state);
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if (lseek(fd, seekback, SEEK_SET) == (off_t) -1)
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return error("cannot seek back");
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}
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git_SHA1_Final(result_sha1, &ctx);
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if (!idx)
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return 0;
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idx->crc32 = crc32_end(state->f);
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if (already_written(state, result_sha1)) {
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sha1file_truncate(state->f, &checkpoint);
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state->offset = checkpoint.offset;
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free(idx);
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} else {
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hashcpy(idx->sha1, result_sha1);
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ALLOC_GROW(state->written,
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state->nr_written + 1,
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state->alloc_written);
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state->written[state->nr_written++] = idx;
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}
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return 0;
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}
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int index_bulk_checkin(unsigned char *sha1,
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int fd, size_t size, enum object_type type,
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const char *path, unsigned flags)
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{
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int status = deflate_to_pack(&state, sha1, fd, size, type,
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path, flags);
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if (!state.plugged)
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finish_bulk_checkin(&state);
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return status;
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}
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void plug_bulk_checkin(void)
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{
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state.plugged = 1;
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}
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void unplug_bulk_checkin(void)
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{
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state.plugged = 0;
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if (state.f)
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finish_bulk_checkin(&state);
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}
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