bulk-checkin.c - jrn/git - Git at Google

 /*
  * Copyright (c) 2011, Google Inc.
  */
 #include "cache.h"
 #include "bulk-checkin.h"
 #include "lockfile.h"
 #include "repository.h"
 #include "csum-file.h"
 #include "pack.h"
 #include "strbuf.h"
 #include "string-list.h"
 #include "tmp-objdir.h"
 #include "packfile.h"
 #include "object-store.h"

 static int odb_transaction_nesting;

 static struct tmp_objdir *bulk_fsync_objdir;

 static struct bulk_checkin_packfile {
 	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;
 } bulk_checkin_packfile;

 static void finish_tmp_packfile(struct strbuf *basename,
 				const char *pack_tmp_name,
 				struct pack_idx_entry **written_list,
 				uint32_t nr_written,
 				struct pack_idx_option *pack_idx_opts,
 				unsigned char hash[])
 {
 	char *idx_tmp_name = NULL;

 	stage_tmp_packfiles(basename, pack_tmp_name, written_list, nr_written,
 			    NULL, pack_idx_opts, hash, &idx_tmp_name);
 	rename_tmp_packfile_idx(basename, &idx_tmp_name);

 	free(idx_tmp_name);
 }

 static void flush_bulk_checkin_packfile(struct bulk_checkin_packfile *state)
 {
 	unsigned char hash[GIT_MAX_RAWSZ];
 	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, hash, FSYNC_COMPONENT_PACK,
 				  CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE);
 	} else {
 		int fd = finalize_hashfile(state->f, hash, FSYNC_COMPONENT_PACK, 0);
 		fixup_pack_header_footer(fd, hash, state->pack_tmp_name,
 					 state->nr_written, hash,
 					 state->offset);
 		close(fd);
 	}

 	strbuf_addf(&packname, "%s/pack/pack-%s.", get_object_directory(),
 		    hash_to_hex(hash));
 	finish_tmp_packfile(&packname, state->pack_tmp_name,
 			    state->written, state->nr_written,
 			    &state->pack_idx_opts, 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);
 }

 /*
  * Cleanup after batch-mode fsync_object_files.
  */
 static void flush_batch_fsync(void)
 {
 	struct strbuf temp_path = STRBUF_INIT;
 	struct tempfile *temp;

 	if (!bulk_fsync_objdir)
 		return;

 	/*
 	 * Issue a full hardware flush against a temporary file to ensure
 	 * that all objects are durable before any renames occur. The code in
 	 * fsync_loose_object_bulk_checkin has already issued a writeout
 	 * request, but it has not flushed any writeback cache in the storage
 	 * hardware or any filesystem logs. This fsync call acts as a barrier
 	 * to ensure that the data in each new object file is durable before
 	 * the final name is visible.
 	 */
 	strbuf_addf(&temp_path, "%s/bulk_fsync_XXXXXX", get_object_directory());
 	temp = xmks_tempfile(temp_path.buf);
 	fsync_or_die(get_tempfile_fd(temp), get_tempfile_path(temp));
 	delete_tempfile(&temp);
 	strbuf_release(&temp_path);

 	/*
 	 * Make the object files visible in the primary ODB after their data is
 	 * fully durable.
 	 */
 	tmp_objdir_migrate(bulk_fsync_objdir);
 	bulk_fsync_objdir = NULL;
 }

 static int already_written(struct bulk_checkin_packfile *state, struct object_id *oid)
 {
 	int i;

 	/* The object may already exist in the repository */
 	if (has_object_file(oid))
 		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_packfile *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 ibuf[16384];
 	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) {
 		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_packfile *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_packfile *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 = {0};
 	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 = format_object_header((char *)obuf, sizeof(obuf),
 					  type, size);
 	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)
 		CALLOC_ARRAY(idx, 1);

 	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;
 		flush_bulk_checkin_packfile(state);
 		if (lseek(fd, seekback, SEEK_SET) == (off_t) -1)
 			return error("cannot seek back");
 	}
 	the_hash_algo->final_oid_fn(result_oid, &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;
 }

 void prepare_loose_object_bulk_checkin(void)
 {
 	/*
 	 * We lazily create the temporary object directory
 	 * the first time an object might be added, since
 	 * callers may not know whether any objects will be
 	 * added at the time they call begin_odb_transaction.
 	 */
 	if (!odb_transaction_nesting || bulk_fsync_objdir)
 		return;

 	bulk_fsync_objdir = tmp_objdir_create("bulk-fsync");
 	if (bulk_fsync_objdir)
 		tmp_objdir_replace_primary_odb(bulk_fsync_objdir, 0);
 }

 void fsync_loose_object_bulk_checkin(int fd, const char *filename)
 {
 	/*
 	 * If we have an active ODB transaction, we issue a call that
 	 * cleans the filesystem page cache but avoids a hardware flush
 	 * command. Later on we will issue a single hardware flush
 	 * before renaming the objects to their final names as part of
 	 * flush_batch_fsync.
 	 */
 	if (!bulk_fsync_objdir ||
 	    git_fsync(fd, FSYNC_WRITEOUT_ONLY) < 0) {
 		fsync_or_die(fd, filename);
 	}
 }

 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(&bulk_checkin_packfile, oid, fd, size, type,
 				     path, flags);
 	if (!odb_transaction_nesting)
 		flush_bulk_checkin_packfile(&bulk_checkin_packfile);
 	return status;
 }

 void begin_odb_transaction(void)
 {
 	odb_transaction_nesting += 1;
 }

 void flush_odb_transaction(void)
 {
 	flush_batch_fsync();
 	flush_bulk_checkin_packfile(&bulk_checkin_packfile);
 }

 void end_odb_transaction(void)
 {
 	odb_transaction_nesting -= 1;
 	if (odb_transaction_nesting < 0)
 		BUG("Unbalanced ODB transaction nesting");

 	if (odb_transaction_nesting)
 		return;

 	flush_odb_transaction();
 }
	/*
	* Copyright (c) 2011, Google Inc.
	*/
	#include "cache.h"
	#include "bulk-checkin.h"
	#include "lockfile.h"
	#include "repository.h"
	#include "csum-file.h"
	#include "pack.h"
	#include "strbuf.h"
	#include "string-list.h"
	#include "tmp-objdir.h"
	#include "packfile.h"
	#include "object-store.h"

	static int odb_transaction_nesting;

	static struct tmp_objdir *bulk_fsync_objdir;

	static struct bulk_checkin_packfile {
	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;
	} bulk_checkin_packfile;

	static void finish_tmp_packfile(struct strbuf *basename,
	const char *pack_tmp_name,
	struct pack_idx_entry **written_list,
	uint32_t nr_written,
	struct pack_idx_option *pack_idx_opts,
	unsigned char hash[])
	{
	char *idx_tmp_name = NULL;

	stage_tmp_packfiles(basename, pack_tmp_name, written_list, nr_written,
	NULL, pack_idx_opts, hash, &idx_tmp_name);
	rename_tmp_packfile_idx(basename, &idx_tmp_name);

	free(idx_tmp_name);
	}

	static void flush_bulk_checkin_packfile(struct bulk_checkin_packfile *state)
	{
	unsigned char hash[GIT_MAX_RAWSZ];
	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, hash, FSYNC_COMPONENT_PACK,
	CSUM_HASH_IN_STREAM \| CSUM_FSYNC \| CSUM_CLOSE);
	} else {
	int fd = finalize_hashfile(state->f, hash, FSYNC_COMPONENT_PACK, 0);
	fixup_pack_header_footer(fd, hash, state->pack_tmp_name,
	state->nr_written, hash,
	state->offset);
	close(fd);
	}

	strbuf_addf(&packname, "%s/pack/pack-%s.", get_object_directory(),
	hash_to_hex(hash));
	finish_tmp_packfile(&packname, state->pack_tmp_name,
	state->written, state->nr_written,
	&state->pack_idx_opts, 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);
	}

	/*
	* Cleanup after batch-mode fsync_object_files.
	*/
	static void flush_batch_fsync(void)
	{
	struct strbuf temp_path = STRBUF_INIT;
	struct tempfile *temp;

	if (!bulk_fsync_objdir)
	return;

	/*
	* Issue a full hardware flush against a temporary file to ensure
	* that all objects are durable before any renames occur. The code in
	* fsync_loose_object_bulk_checkin has already issued a writeout
	* request, but it has not flushed any writeback cache in the storage
	* hardware or any filesystem logs. This fsync call acts as a barrier
	* to ensure that the data in each new object file is durable before
	* the final name is visible.
	*/
	strbuf_addf(&temp_path, "%s/bulk_fsync_XXXXXX", get_object_directory());
	temp = xmks_tempfile(temp_path.buf);
	fsync_or_die(get_tempfile_fd(temp), get_tempfile_path(temp));
	delete_tempfile(&temp);
	strbuf_release(&temp_path);

	/*
	* Make the object files visible in the primary ODB after their data is
	* fully durable.
	*/
	tmp_objdir_migrate(bulk_fsync_objdir);
	bulk_fsync_objdir = NULL;
	}

	static int already_written(struct bulk_checkin_packfile state, struct object_id oid)
	{
	int i;

	/* The object may already exist in the repository */
	if (has_object_file(oid))
	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_packfile *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 ibuf[16384];
	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) {
	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_packfile *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_packfile *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 = {0};
	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 = format_object_header((char *)obuf, sizeof(obuf),
	type, size);
	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)
	CALLOC_ARRAY(idx, 1);

	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;
	flush_bulk_checkin_packfile(state);
	if (lseek(fd, seekback, SEEK_SET) == (off_t) -1)
	return error("cannot seek back");
	}
	the_hash_algo->final_oid_fn(result_oid, &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;
	}

	void prepare_loose_object_bulk_checkin(void)
	{
	/*
	* We lazily create the temporary object directory
	* the first time an object might be added, since
	* callers may not know whether any objects will be
	* added at the time they call begin_odb_transaction.
	*/
	if (!odb_transaction_nesting \|\| bulk_fsync_objdir)
	return;

	bulk_fsync_objdir = tmp_objdir_create("bulk-fsync");
	if (bulk_fsync_objdir)
	tmp_objdir_replace_primary_odb(bulk_fsync_objdir, 0);
	}

	void fsync_loose_object_bulk_checkin(int fd, const char *filename)
	{
	/*
	* If we have an active ODB transaction, we issue a call that
	* cleans the filesystem page cache but avoids a hardware flush
	* command. Later on we will issue a single hardware flush
	* before renaming the objects to their final names as part of
	* flush_batch_fsync.
	*/
	if (!bulk_fsync_objdir \|\|
	git_fsync(fd, FSYNC_WRITEOUT_ONLY) < 0) {
	fsync_or_die(fd, filename);
	}
	}

	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(&bulk_checkin_packfile, oid, fd, size, type,
	path, flags);
	if (!odb_transaction_nesting)
	flush_bulk_checkin_packfile(&bulk_checkin_packfile);
	return status;
	}

	void begin_odb_transaction(void)
	{
	odb_transaction_nesting += 1;
	}

	void flush_odb_transaction(void)
	{
	flush_batch_fsync();
	flush_bulk_checkin_packfile(&bulk_checkin_packfile);
	}

	void end_odb_transaction(void)
	{
	odb_transaction_nesting -= 1;
	if (odb_transaction_nesting < 0)
	BUG("Unbalanced ODB transaction nesting");

	if (odb_transaction_nesting)
	return;

	flush_odb_transaction();
	}