bulk-checkin.c

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