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authorJunio C Hamano <gitster@pobox.com>2011-10-28 14:48:40 -0700
committerJunio C Hamano <gitster@pobox.com>2011-12-01 11:46:09 -0800
commit568508e76570e9ea36aad6446959424cebcf0535 (patch)
tree9b71da7197e9a084c3406d6020672dd11ac26b24 /bulk-checkin.c
parent6c526148644475acbc047faaeb57d42fde1f667d (diff)
downloadgit-568508e76570e9ea36aad6446959424cebcf0535.tar.gz
bulk-checkin: replace fast-import based implementationjc/stream-to-pack
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>
Diffstat (limited to 'bulk-checkin.c')
-rw-r--r--bulk-checkin.c275
1 files changed, 275 insertions, 0 deletions
diff --git a/bulk-checkin.c b/bulk-checkin.c
new file mode 100644
index 0000000000..6b0b6d4904
--- /dev/null
+++ b/bulk-checkin.c
@@ -0,0 +1,275 @@
+/*
+ * Copyright (c) 2011, Google Inc.
+ */
+#include "bulk-checkin.h"
+#include "csum-file.h"
+#include "pack.h"
+
+static int pack_compression_level = Z_DEFAULT_COMPRESSION;
+
+static struct bulk_checkin_state {
+ unsigned plugged:1;
+
+ char *pack_tmp_name;
+ struct sha1file *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)
+{
+ unsigned char sha1[20];
+ char packname[PATH_MAX];
+ 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) {
+ sha1close(state->f, sha1, CSUM_FSYNC);
+ } else {
+ int fd = sha1close(state->f, sha1, 0);
+ fixup_pack_header_footer(fd, sha1, state->pack_tmp_name,
+ state->nr_written, sha1,
+ state->offset);
+ close(fd);
+ }
+
+ sprintf(packname, "%s/pack/pack-", get_object_directory());
+ finish_tmp_packfile(packname, state->pack_tmp_name,
+ state->written, state->nr_written,
+ &state->pack_idx_opts, sha1);
+ for (i = 0; i < state->nr_written; i++)
+ free(state->written[i]);
+
+clear_exit:
+ free(state->written);
+ memset(state, 0, sizeof(*state));
+
+ /* Make objects we just wrote available to ourselves */
+ reprepare_packed_git();
+}
+
+static int already_written(struct bulk_checkin_state *state, unsigned char sha1[])
+{
+ int i;
+
+ /* The object may already exist in the repository */
+ if (has_sha1_file(sha1))
+ return 1;
+
+ /* Might want to keep the list sorted */
+ for (i = 0; i < state->nr_written; i++)
+ if (!hashcmp(state->written[i]->sha1, sha1))
+ 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_SHA_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;
+
+ memset(&s, 0, sizeof(s));
+ git_deflate_init(&s, pack_compression_level);
+
+ hdrlen = encode_in_pack_object_header(type, size, obuf);
+ 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);
+ if (xread(fd, ibuf, rsize) != 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)
+ git_SHA1_Update(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;
+ }
+
+ sha1write(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,
+ unsigned char result_sha1[],
+ int fd, size_t size,
+ enum object_type type, const char *path,
+ unsigned flags)
+{
+ off_t seekback, already_hashed_to;
+ git_SHA_CTX ctx;
+ unsigned char obuf[16384];
+ unsigned header_len;
+ struct sha1file_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 = sprintf((char *)obuf, "%s %" PRIuMAX,
+ typename(type), (uintmax_t)size) + 1;
+ git_SHA1_Init(&ctx);
+ git_SHA1_Update(&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) {
+ sha1file_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)
+ die("BUG: should not happen");
+ sha1file_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");
+ }
+ git_SHA1_Final(result_sha1, &ctx);
+ if (!idx)
+ return 0;
+
+ idx->crc32 = crc32_end(state->f);
+ if (already_written(state, result_sha1)) {
+ sha1file_truncate(state->f, &checkpoint);
+ state->offset = checkpoint.offset;
+ free(idx);
+ } else {
+ hashcpy(idx->sha1, result_sha1);
+ ALLOC_GROW(state->written,
+ state->nr_written + 1,
+ state->alloc_written);
+ state->written[state->nr_written++] = idx;
+ }
+ return 0;
+}
+
+int index_bulk_checkin(unsigned char *sha1,
+ int fd, size_t size, enum object_type type,
+ const char *path, unsigned flags)
+{
+ int status = deflate_to_pack(&state, sha1, 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);
+}