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 "string-list.h"
  15 #include "tmp-objdir.h"
  16 #include "packfile.h"
  17 #include "object-file.h"
  18 #include "object-store-ll.h"
  19
  20 static int odb_transaction_nesting;
  21
  22 static struct tmp_objdir *bulk_fsync_objdir;
  23
  24 static struct bulk_checkin_packfile {
  25         char *pack_tmp_name;
  26         struct hashfile *f;
  27         off_t offset;
  28         struct pack_idx_option pack_idx_opts;
  29
  30         struct pack_idx_entry **written;
  31         uint32_t alloc_written;
  32         uint32_t nr_written;
  33 } bulk_checkin_packfile;
  34
  35 static void finish_tmp_packfile(struct strbuf *basename,
  36                                 const char *pack_tmp_name,
  37                                 struct pack_idx_entry **written_list,
  38                                 uint32_t nr_written,
  39                                 struct pack_idx_option *pack_idx_opts,
  40                                 unsigned char hash[])
  41 {
  42         char *idx_tmp_name = NULL;
  43
  44         stage_tmp_packfiles(basename, pack_tmp_name, written_list, nr_written,
  45                             NULL, pack_idx_opts, hash, &idx_tmp_name);
  46         rename_tmp_packfile_idx(basename, &idx_tmp_name);
  47
  48         free(idx_tmp_name);
  49 }
  50
  51 static void flush_bulk_checkin_packfile(struct bulk_checkin_packfile *state)
  52 {
  53         unsigned char hash[GIT_MAX_RAWSZ];
  54         struct strbuf packname = STRBUF_INIT;
  55         int i;
  56
  57         if (!state->f)
  58                 return;
  59
  60         if (state->nr_written == 0) {
  61                 close(state->f->fd);
  62                 unlink(state->pack_tmp_name);
  63                 goto clear_exit;
  64         } else if (state->nr_written == 1) {
  65                 finalize_hashfile(state->f, hash, FSYNC_COMPONENT_PACK,
  66                                   CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE);
  67         } else {
  68                 int fd = finalize_hashfile(state->f, hash, FSYNC_COMPONENT_PACK, 0);
  69                 fixup_pack_header_footer(fd, hash, state->pack_tmp_name,
  70                                          state->nr_written, hash,
  71                                          state->offset);
  72                 close(fd);
  73         }
  74
  75         strbuf_addf(&packname, "%s/pack/pack-%s.", get_object_directory(),
  76                     hash_to_hex(hash));
  77         finish_tmp_packfile(&packname, state->pack_tmp_name,
  78                             state->written, state->nr_written,
  79                             &state->pack_idx_opts, hash);
  80         for (i = 0; i < state->nr_written; i++)
  81                 free(state->written[i]);
  82
  83 clear_exit:
  84         free(state->written);
  85         memset(state, 0, sizeof(*state));
  86
  87         strbuf_release(&packname);
  88         /* Make objects we just wrote available to ourselves */
  89         reprepare_packed_git(the_repository);
  90 }
  91
  92 /*
  93  * Cleanup after batch-mode fsync_object_files.
  94  */
  95 static void flush_batch_fsync(void)
  96 {
  97         struct strbuf temp_path = STRBUF_INIT;
  98         struct tempfile *temp;
  99
 100         if (!bulk_fsync_objdir)
 101                 return;
 102
 103         /*
 104          * Issue a full hardware flush against a temporary file to ensure
 105          * that all objects are durable before any renames occur. The code in
 106          * fsync_loose_object_bulk_checkin has already issued a writeout
 107          * request, but it has not flushed any writeback cache in the storage
 108          * hardware or any filesystem logs. This fsync call acts as a barrier
 109          * to ensure that the data in each new object file is durable before
 110          * the final name is visible.
 111          */
 112         strbuf_addf(&temp_path, "%s/bulk_fsync_XXXXXX", get_object_directory());
 113         temp = xmks_tempfile(temp_path.buf);
 114         fsync_or_die(get_tempfile_fd(temp), get_tempfile_path(temp));
 115         delete_tempfile(&temp);
 116         strbuf_release(&temp_path);
 117
 118         /*
 119          * Make the object files visible in the primary ODB after their data is
 120          * fully durable.
 121          */
 122         tmp_objdir_migrate(bulk_fsync_objdir);
 123         bulk_fsync_objdir = NULL;
 124 }
 125
 126 static int already_written(struct bulk_checkin_packfile *state, struct object_id *oid)
 127 {
 128         int i;
 129
 130         /* The object may already exist in the repository */
 131         if (repo_has_object_file(the_repository, oid))
 132                 return 1;
 133
 134         /* Might want to keep the list sorted */
 135         for (i = 0; i < state->nr_written; i++)
 136                 if (oideq(&state->written[i]->oid, oid))
 137                         return 1;
 138
 139         /* This is a new object we need to keep */
 140         return 0;
 141 }
 142
 143 /*
 144  * Read the contents from fd for size bytes, streaming it to the
 145  * packfile in state while updating the hash in ctx. Signal a failure
 146  * by returning a negative value when the resulting pack would exceed
 147  * the pack size limit and this is not the first object in the pack,
 148  * so that the caller can discard what we wrote from the current pack
 149  * by truncating it and opening a new one. The caller will then call
 150  * us again after rewinding the input fd.
 151  *
 152  * The already_hashed_to pointer is kept untouched by the caller to
 153  * make sure we do not hash the same byte when we are called
 154  * again. This way, the caller does not have to checkpoint its hash
 155  * status before calling us just in case we ask it to call us again
 156  * with a new pack.
 157  */
 158 static int stream_to_pack(struct bulk_checkin_packfile *state,
 159                           git_hash_ctx *ctx, off_t *already_hashed_to,
 160                           int fd, size_t size, enum object_type type,
 161                           const char *path, unsigned flags)
 162 {
 163         git_zstream s;
 164         unsigned char ibuf[16384];
 165         unsigned char obuf[16384];
 166         unsigned hdrlen;
 167         int status = Z_OK;
 168         int write_object = (flags & HASH_WRITE_OBJECT);
 169         off_t offset = 0;
 170
 171         git_deflate_init(&s, pack_compression_level);
 172
 173         hdrlen = encode_in_pack_object_header(obuf, sizeof(obuf), type, size);
 174         s.next_out = obuf + hdrlen;
 175         s.avail_out = sizeof(obuf) - hdrlen;
 176
 177         while (status != Z_STREAM_END) {
 178                 if (size && !s.avail_in) {
 179                         ssize_t rsize = size < sizeof(ibuf) ? size : sizeof(ibuf);
 180                         ssize_t read_result = read_in_full(fd, ibuf, rsize);
 181                         if (read_result < 0)
 182                                 die_errno("failed to read from '%s'", path);
 183                         if (read_result != rsize)
 184                                 die("failed to read %d bytes from '%s'",
 185                                     (int)rsize, path);
 186                         offset += rsize;
 187                         if (*already_hashed_to < offset) {
 188                                 size_t hsize = offset - *already_hashed_to;
 189                                 if (rsize < hsize)
 190                                         hsize = rsize;
 191                                 if (hsize)
 192                                         the_hash_algo->update_fn(ctx, ibuf, hsize);
 193                                 *already_hashed_to = offset;
 194                         }
 195                         s.next_in = ibuf;
 196                         s.avail_in = rsize;
 197                         size -= rsize;
 198                 }
 199
 200                 status = git_deflate(&s, size ? 0 : Z_FINISH);
 201
 202                 if (!s.avail_out || status == Z_STREAM_END) {
 203                         if (write_object) {
 204                                 size_t written = s.next_out - obuf;
 205
 206                                 /* would we bust the size limit? */
 207                                 if (state->nr_written &&
 208                                     pack_size_limit_cfg &&
 209                                     pack_size_limit_cfg < state->offset + written) {
 210                                         git_deflate_abort(&s);
 211                                         return -1;
 212                                 }
 213
 214                                 hashwrite(state->f, obuf, written);
 215                                 state->offset += written;
 216                         }
 217                         s.next_out = obuf;
 218                         s.avail_out = sizeof(obuf);
 219                 }
 220
 221                 switch (status) {
 222                 case Z_OK:
 223                 case Z_BUF_ERROR:
 224                 case Z_STREAM_END:
 225                         continue;
 226                 default:
 227                         die("unexpected deflate failure: %d", status);
 228                 }
 229         }
 230         git_deflate_end(&s);
 231         return 0;
 232 }
 233
 234 /* Lazily create backing packfile for the state */
 235 static void prepare_to_stream(struct bulk_checkin_packfile *state,
 236                               unsigned flags)
 237 {
 238         if (!(flags & HASH_WRITE_OBJECT) || state->f)
 239                 return;
 240
 241         state->f = create_tmp_packfile(&state->pack_tmp_name);
 242         reset_pack_idx_option(&state->pack_idx_opts);
 243
 244         /* Pretend we are going to write only one object */
 245         state->offset = write_pack_header(state->f, 1);
 246         if (!state->offset)
 247                 die_errno("unable to write pack header");
 248 }
 249
 250 static int deflate_to_pack(struct bulk_checkin_packfile *state,
 251                            struct object_id *result_oid,
 252                            int fd, size_t size,
 253                            enum object_type type, const char *path,
 254                            unsigned flags)
 255 {
 256         off_t seekback, already_hashed_to;
 257         git_hash_ctx ctx;
 258         unsigned char obuf[16384];
 259         unsigned header_len;
 260         struct hashfile_checkpoint checkpoint = {0};
 261         struct pack_idx_entry *idx = NULL;
 262
 263         seekback = lseek(fd, 0, SEEK_CUR);
 264         if (seekback == (off_t) -1)
 265                 return error("cannot find the current offset");
 266
 267         header_len = format_object_header((char *)obuf, sizeof(obuf),
 268                                           type, size);
 269         the_hash_algo->init_fn(&ctx);
 270         the_hash_algo->update_fn(&ctx, obuf, header_len);
 271         the_hash_algo->init_fn(&checkpoint.ctx);
 272
 273         /* Note: idx is non-NULL when we are writing */
 274         if ((flags & HASH_WRITE_OBJECT) != 0)
 275                 CALLOC_ARRAY(idx, 1);
 276
 277         already_hashed_to = 0;
 278
 279         while (1) {
 280                 prepare_to_stream(state, flags);
 281                 if (idx) {
 282                         hashfile_checkpoint(state->f, &checkpoint);
 283                         idx->offset = state->offset;
 284                         crc32_begin(state->f);
 285                 }
 286                 if (!stream_to_pack(state, &ctx, &already_hashed_to,
 287                                     fd, size, type, path, flags))
 288                         break;
 289                 /*
 290                  * Writing this object to the current pack will make
 291                  * it too big; we need to truncate it, start a new
 292                  * pack, and write into it.
 293                  */
 294                 if (!idx)
 295                         BUG("should not happen");
 296                 hashfile_truncate(state->f, &checkpoint);
 297                 state->offset = checkpoint.offset;
 298                 flush_bulk_checkin_packfile(state);
 299                 if (lseek(fd, seekback, SEEK_SET) == (off_t) -1)
 300                         return error("cannot seek back");
 301         }
 302         the_hash_algo->final_oid_fn(result_oid, &ctx);
 303         if (!idx)
 304                 return 0;
 305
 306         idx->crc32 = crc32_end(state->f);
 307         if (already_written(state, result_oid)) {
 308                 hashfile_truncate(state->f, &checkpoint);
 309                 state->offset = checkpoint.offset;
 310                 free(idx);
 311         } else {
 312                 oidcpy(&idx->oid, result_oid);
 313                 ALLOC_GROW(state->written,
 314                            state->nr_written + 1,
 315                            state->alloc_written);
 316                 state->written[state->nr_written++] = idx;
 317         }
 318         return 0;
 319 }
 320
 321 void prepare_loose_object_bulk_checkin(void)
 322 {
 323         /*
 324          * We lazily create the temporary object directory
 325          * the first time an object might be added, since
 326          * callers may not know whether any objects will be
 327          * added at the time they call begin_odb_transaction.
 328          */
 329         if (!odb_transaction_nesting || bulk_fsync_objdir)
 330                 return;
 331
 332         bulk_fsync_objdir = tmp_objdir_create("bulk-fsync");
 333         if (bulk_fsync_objdir)
 334                 tmp_objdir_replace_primary_odb(bulk_fsync_objdir, 0);
 335 }
 336
 337 void fsync_loose_object_bulk_checkin(int fd, const char *filename)
 338 {
 339         /*
 340          * If we have an active ODB transaction, we issue a call that
 341          * cleans the filesystem page cache but avoids a hardware flush
 342          * command. Later on we will issue a single hardware flush
 343          * before renaming the objects to their final names as part of
 344          * flush_batch_fsync.
 345          */
 346         if (!bulk_fsync_objdir ||
 347             git_fsync(fd, FSYNC_WRITEOUT_ONLY) < 0) {
 348                 if (errno == ENOSYS)
 349                         warning(_("core.fsyncMethod = batch is unsupported on this platform"));
 350                 fsync_or_die(fd, filename);
 351         }
 352 }
 353
 354 int index_bulk_checkin(struct object_id *oid,
 355                        int fd, size_t size, enum object_type type,
 356                        const char *path, unsigned flags)
 357 {
 358         int status = deflate_to_pack(&bulk_checkin_packfile, oid, fd, size, type,
 359                                      path, flags);
 360         if (!odb_transaction_nesting)
 361                 flush_bulk_checkin_packfile(&bulk_checkin_packfile);
 362         return status;
 363 }
 364
 365 void begin_odb_transaction(void)
 366 {
 367         odb_transaction_nesting += 1;
 368 }
 369
 370 void flush_odb_transaction(void)
 371 {
 372         flush_batch_fsync();
 373         flush_bulk_checkin_packfile(&bulk_checkin_packfile);
 374 }
 375
 376 void end_odb_transaction(void)
 377 {
 378         odb_transaction_nesting -= 1;
 379         if (odb_transaction_nesting < 0)
 380                 BUG("Unbalanced ODB transaction nesting");
 381
 382         if (odb_transaction_nesting)
 383                 return;
 384
 385         flush_odb_transaction();
 386 }