bulk-checkin.c

   1 /*
   2  * Copyright (c) 2011, Google Inc.
   3  */
   4 #include "git-compat-util.h"
   5 #include "bulk-checkin.h"
   6 #include "environment.h"
   7 #include "gettext.h"
   8 #include "hex.h"
   9 #include "lockfile.h"
  10 #include "repository.h"
  11 #include "csum-file.h"
  12 #include "pack.h"
  13 #include "strbuf.h"
  14 #include "tmp-objdir.h"
  15 #include "packfile.h"
  16 #include "object-file.h"
  17 #include "object-store-ll.h"
  18
  19 static int odb_transaction_nesting;
  20
  21 static struct tmp_objdir *bulk_fsync_objdir;
  22
  23 static struct bulk_checkin_packfile {
  24         char *pack_tmp_name;
  25         struct hashfile *f;
  26         off_t offset;
  27         struct pack_idx_option pack_idx_opts;
  28
  29         struct pack_idx_entry **written;
  30         uint32_t alloc_written;
  31         uint32_t nr_written;
  32 } bulk_checkin_packfile;
  33
  34 static void finish_tmp_packfile(struct strbuf *basename,
  35                                 const char *pack_tmp_name,
  36                                 struct pack_idx_entry **written_list,
  37                                 uint32_t nr_written,
  38                                 struct pack_idx_option *pack_idx_opts,
  39                                 unsigned char hash[])
  40 {
  41         char *idx_tmp_name = NULL;
  42
  43         stage_tmp_packfiles(basename, pack_tmp_name, written_list, nr_written,
  44                             NULL, pack_idx_opts, hash, &idx_tmp_name);
  45         rename_tmp_packfile_idx(basename, &idx_tmp_name);
  46
  47         free(idx_tmp_name);
  48 }
  49
  50 static void flush_bulk_checkin_packfile(struct bulk_checkin_packfile *state)
  51 {
  52         unsigned char hash[GIT_MAX_RAWSZ];
  53         struct strbuf packname = STRBUF_INIT;
  54         int i;
  55
  56         if (!state->f)
  57                 return;
  58
  59         if (state->nr_written == 0) {
  60                 close(state->f->fd);
  61                 unlink(state->pack_tmp_name);
  62                 goto clear_exit;
  63         } else if (state->nr_written == 1) {
  64                 finalize_hashfile(state->f, hash, FSYNC_COMPONENT_PACK,
  65                                   CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE);
  66         } else {
  67                 int fd = finalize_hashfile(state->f, hash, FSYNC_COMPONENT_PACK, 0);
  68                 fixup_pack_header_footer(fd, hash, state->pack_tmp_name,
  69                                          state->nr_written, hash,
  70                                          state->offset);
  71                 close(fd);
  72         }
  73
  74         strbuf_addf(&packname, "%s/pack/pack-%s.", get_object_directory(),
  75                     hash_to_hex(hash));
  76         finish_tmp_packfile(&packname, state->pack_tmp_name,
  77                             state->written, state->nr_written,
  78                             &state->pack_idx_opts, hash);
  79         for (i = 0; i < state->nr_written; i++)
  80                 free(state->written[i]);
  81
  82 clear_exit:
  83         free(state->written);
  84         memset(state, 0, sizeof(*state));
  85
  86         strbuf_release(&packname);
  87         /* Make objects we just wrote available to ourselves */
  88         reprepare_packed_git(the_repository);
  89 }
  90
  91 /*
  92  * Cleanup after batch-mode fsync_object_files.
  93  */
  94 static void flush_batch_fsync(void)
  95 {
  96         struct strbuf temp_path = STRBUF_INIT;
  97         struct tempfile *temp;
  98
  99         if (!bulk_fsync_objdir)
 100                 return;
 101
 102         /*
 103          * Issue a full hardware flush against a temporary file to ensure
 104          * that all objects are durable before any renames occur. The code in
 105          * fsync_loose_object_bulk_checkin has already issued a writeout
 106          * request, but it has not flushed any writeback cache in the storage
 107          * hardware or any filesystem logs. This fsync call acts as a barrier
 108          * to ensure that the data in each new object file is durable before
 109          * the final name is visible.
 110          */
 111         strbuf_addf(&temp_path, "%s/bulk_fsync_XXXXXX", get_object_directory());
 112         temp = xmks_tempfile(temp_path.buf);
 113         fsync_or_die(get_tempfile_fd(temp), get_tempfile_path(temp));
 114         delete_tempfile(&temp);
 115         strbuf_release(&temp_path);
 116
 117         /*
 118          * Make the object files visible in the primary ODB after their data is
 119          * fully durable.
 120          */
 121         tmp_objdir_migrate(bulk_fsync_objdir);
 122         bulk_fsync_objdir = NULL;
 123 }
 124
 125 static int already_written(struct bulk_checkin_packfile *state, struct object_id *oid)
 126 {
 127         int i;
 128
 129         /* The object may already exist in the repository */
 130         if (repo_has_object_file(the_repository, oid))
 131                 return 1;
 132
 133         /* Might want to keep the list sorted */
 134         for (i = 0; i < state->nr_written; i++)
 135                 if (oideq(&state->written[i]->oid, oid))
 136                         return 1;
 137
 138         /* This is a new object we need to keep */
 139         return 0;
 140 }
 141
 142 /*
 143  * Read the contents from fd for size bytes, streaming it to the
 144  * packfile in state while updating the hash in ctx. Signal a failure
 145  * by returning a negative value when the resulting pack would exceed
 146  * the pack size limit and this is not the first object in the pack,
 147  * so that the caller can discard what we wrote from the current pack
 148  * by truncating it and opening a new one. The caller will then call
 149  * us again after rewinding the input fd.
 150  *
 151  * The already_hashed_to pointer is kept untouched by the caller to
 152  * make sure we do not hash the same byte when we are called
 153  * again. This way, the caller does not have to checkpoint its hash
 154  * status before calling us just in case we ask it to call us again
 155  * with a new pack.
 156  */
 157 static int stream_blob_to_pack(struct bulk_checkin_packfile *state,
 158                                git_hash_ctx *ctx, off_t *already_hashed_to,
 159                                int fd, size_t size, const char *path,
 160                                unsigned flags)
 161 {
 162         git_zstream s;
 163         unsigned char ibuf[16384];
 164         unsigned char obuf[16384];
 165         unsigned hdrlen;
 166         int status = Z_OK;
 167         int write_object = (flags & HASH_WRITE_OBJECT);
 168         off_t offset = 0;
 169
 170         git_deflate_init(&s, pack_compression_level);
 171
 172         hdrlen = encode_in_pack_object_header(obuf, sizeof(obuf), OBJ_BLOB, size);
 173         s.next_out = obuf + hdrlen;
 174         s.avail_out = sizeof(obuf) - hdrlen;
 175
 176         while (status != Z_STREAM_END) {
 177                 if (size && !s.avail_in) {
 178                         ssize_t rsize = size < sizeof(ibuf) ? size : sizeof(ibuf);
 179                         ssize_t read_result = read_in_full(fd, ibuf, rsize);
 180                         if (read_result < 0)
 181                                 die_errno("failed to read from '%s'", path);
 182                         if (read_result != rsize)
 183                                 die("failed to read %d bytes from '%s'",
 184                                     (int)rsize, path);
 185                         offset += rsize;
 186                         if (*already_hashed_to < offset) {
 187                                 size_t hsize = offset - *already_hashed_to;
 188                                 if (rsize < hsize)
 189                                         hsize = rsize;
 190                                 if (hsize)
 191                                         the_hash_algo->update_fn(ctx, ibuf, hsize);
 192                                 *already_hashed_to = offset;
 193                         }
 194                         s.next_in = ibuf;
 195                         s.avail_in = rsize;
 196                         size -= rsize;
 197                 }
 198
 199                 status = git_deflate(&s, size ? 0 : Z_FINISH);
 200
 201                 if (!s.avail_out || status == Z_STREAM_END) {
 202                         if (write_object) {
 203                                 size_t written = s.next_out - obuf;
 204
 205                                 /* would we bust the size limit? */
 206                                 if (state->nr_written &&
 207                                     pack_size_limit_cfg &&
 208                                     pack_size_limit_cfg < state->offset + written) {
 209                                         git_deflate_abort(&s);
 210                                         return -1;
 211                                 }
 212
 213                                 hashwrite(state->f, obuf, written);
 214                                 state->offset += written;
 215                         }
 216                         s.next_out = obuf;
 217                         s.avail_out = sizeof(obuf);
 218                 }
 219
 220                 switch (status) {
 221                 case Z_OK:
 222                 case Z_BUF_ERROR:
 223                 case Z_STREAM_END:
 224                         continue;
 225                 default:
 226                         die("unexpected deflate failure: %d", status);
 227                 }
 228         }
 229         git_deflate_end(&s);
 230         return 0;
 231 }
 232
 233 /* Lazily create backing packfile for the state */
 234 static void prepare_to_stream(struct bulk_checkin_packfile *state,
 235                               unsigned flags)
 236 {
 237         if (!(flags & HASH_WRITE_OBJECT) || state->f)
 238                 return;
 239
 240         state->f = create_tmp_packfile(&state->pack_tmp_name);
 241         reset_pack_idx_option(&state->pack_idx_opts);
 242
 243         /* Pretend we are going to write only one object */
 244         state->offset = write_pack_header(state->f, 1);
 245         if (!state->offset)
 246                 die_errno("unable to write pack header");
 247 }
 248
 249 static int deflate_blob_to_pack(struct bulk_checkin_packfile *state,
 250                                 struct object_id *result_oid,
 251                                 int fd, size_t size,
 252                                 const char *path, unsigned flags)
 253 {
 254         off_t seekback, already_hashed_to;
 255         git_hash_ctx ctx;
 256         unsigned char obuf[16384];
 257         unsigned header_len;
 258         struct hashfile_checkpoint checkpoint = {0};
 259         struct pack_idx_entry *idx = NULL;
 260
 261         seekback = lseek(fd, 0, SEEK_CUR);
 262         if (seekback == (off_t) -1)
 263                 return error("cannot find the current offset");
 264
 265         header_len = format_object_header((char *)obuf, sizeof(obuf),
 266                                           OBJ_BLOB, size);
 267         the_hash_algo->init_fn(&ctx);
 268         the_hash_algo->update_fn(&ctx, obuf, header_len);
 269         the_hash_algo->init_fn(&checkpoint.ctx);
 270
 271         /* Note: idx is non-NULL when we are writing */
 272         if ((flags & HASH_WRITE_OBJECT) != 0)
 273                 CALLOC_ARRAY(idx, 1);
 274
 275         already_hashed_to = 0;
 276
 277         while (1) {
 278                 prepare_to_stream(state, flags);
 279                 if (idx) {
 280                         hashfile_checkpoint(state->f, &checkpoint);
 281                         idx->offset = state->offset;
 282                         crc32_begin(state->f);
 283                 }
 284                 if (!stream_blob_to_pack(state, &ctx, &already_hashed_to,
 285                                          fd, size, path, flags))
 286                         break;
 287                 /*
 288                  * Writing this object to the current pack will make
 289                  * it too big; we need to truncate it, start a new
 290                  * pack, and write into it.
 291                  */
 292                 if (!idx)
 293                         BUG("should not happen");
 294                 hashfile_truncate(state->f, &checkpoint);
 295                 state->offset = checkpoint.offset;
 296                 flush_bulk_checkin_packfile(state);
 297                 if (lseek(fd, seekback, SEEK_SET) == (off_t) -1)
 298                         return error("cannot seek back");
 299         }
 300         the_hash_algo->final_oid_fn(result_oid, &ctx);
 301         if (!idx)
 302                 return 0;
 303
 304         idx->crc32 = crc32_end(state->f);
 305         if (already_written(state, result_oid)) {
 306                 hashfile_truncate(state->f, &checkpoint);
 307                 state->offset = checkpoint.offset;
 308                 free(idx);
 309         } else {
 310                 oidcpy(&idx->oid, result_oid);
 311                 ALLOC_GROW(state->written,
 312                            state->nr_written + 1,
 313                            state->alloc_written);
 314                 state->written[state->nr_written++] = idx;
 315         }
 316         return 0;
 317 }
 318
 319 void prepare_loose_object_bulk_checkin(void)
 320 {
 321         /*
 322          * We lazily create the temporary object directory
 323          * the first time an object might be added, since
 324          * callers may not know whether any objects will be
 325          * added at the time they call begin_odb_transaction.
 326          */
 327         if (!odb_transaction_nesting || bulk_fsync_objdir)
 328                 return;
 329
 330         bulk_fsync_objdir = tmp_objdir_create("bulk-fsync");
 331         if (bulk_fsync_objdir)
 332                 tmp_objdir_replace_primary_odb(bulk_fsync_objdir, 0);
 333 }
 334
 335 void fsync_loose_object_bulk_checkin(int fd, const char *filename)
 336 {
 337         /*
 338          * If we have an active ODB transaction, we issue a call that
 339          * cleans the filesystem page cache but avoids a hardware flush
 340          * command. Later on we will issue a single hardware flush
 341          * before renaming the objects to their final names as part of
 342          * flush_batch_fsync.
 343          */
 344         if (!bulk_fsync_objdir ||
 345             git_fsync(fd, FSYNC_WRITEOUT_ONLY) < 0) {
 346                 if (errno == ENOSYS)
 347                         warning(_("core.fsyncMethod = batch is unsupported on this platform"));
 348                 fsync_or_die(fd, filename);
 349         }
 350 }
 351
 352 int index_blob_bulk_checkin(struct object_id *oid,
 353                             int fd, size_t size,
 354                             const char *path, unsigned flags)
 355 {
 356         int status = deflate_blob_to_pack(&bulk_checkin_packfile, oid, fd, size,
 357                                           path, flags);
 358         if (!odb_transaction_nesting)
 359                 flush_bulk_checkin_packfile(&bulk_checkin_packfile);
 360         return status;
 361 }
 362
 363 void begin_odb_transaction(void)
 364 {
 365         odb_transaction_nesting += 1;
 366 }
 367
 368 void flush_odb_transaction(void)
 369 {
 370         flush_batch_fsync();
 371         flush_bulk_checkin_packfile(&bulk_checkin_packfile);
 372 }
 373
 374 void end_odb_transaction(void)
 375 {
 376         odb_transaction_nesting -= 1;
 377         if (odb_transaction_nesting < 0)
 378                 BUG("Unbalanced ODB transaction nesting");
 379
 380         if (odb_transaction_nesting)
 381                 return;
 382
 383         flush_odb_transaction();
 384 }