bulk-checkin.c

   1 /*
   2  * Copyright (c) 2011, Google Inc.
   3  */
   4 #include "cache.h"
   5 #include "bulk-checkin.h"
   6 #include "repository.h"
   7 #include "csum-file.h"
   8 #include "pack.h"
   9 #include "strbuf.h"
  10 #include "packfile.h"
  11
  12 static struct bulk_checkin_state {
  13         unsigned plugged:1;
  14
  15         char *pack_tmp_name;
  16         struct hashfile *f;
  17         off_t offset;
  18         struct pack_idx_option pack_idx_opts;
  19
  20         struct pack_idx_entry **written;
  21         uint32_t alloc_written;
  22         uint32_t nr_written;
  23 } state;
  24
  25 static void finish_bulk_checkin(struct bulk_checkin_state *state)
  26 {
  27         struct object_id oid;
  28         struct strbuf packname = STRBUF_INIT;
  29         int i;
  30
  31         if (!state->f)
  32                 return;
  33
  34         if (state->nr_written == 0) {
  35                 close(state->f->fd);
  36                 unlink(state->pack_tmp_name);
  37                 goto clear_exit;
  38         } else if (state->nr_written == 1) {
  39                 hashclose(state->f, oid.hash, CSUM_FSYNC);
  40         } else {
  41                 int fd = hashclose(state->f, oid.hash, 0);
  42                 fixup_pack_header_footer(fd, oid.hash, state->pack_tmp_name,
  43                                          state->nr_written, oid.hash,
  44                                          state->offset);
  45                 close(fd);
  46         }
  47
  48         strbuf_addf(&packname, "%s/pack/pack-", get_object_directory());
  49         finish_tmp_packfile(&packname, state->pack_tmp_name,
  50                             state->written, state->nr_written,
  51                             &state->pack_idx_opts, oid.hash);
  52         for (i = 0; i < state->nr_written; i++)
  53                 free(state->written[i]);
  54
  55 clear_exit:
  56         free(state->written);
  57         memset(state, 0, sizeof(*state));
  58
  59         strbuf_release(&packname);
  60         /* Make objects we just wrote available to ourselves */
  61         reprepare_packed_git(the_repository);
  62 }
  63
  64 static int already_written(struct bulk_checkin_state *state, struct object_id *oid)
  65 {
  66         int i;
  67
  68         /* The object may already exist in the repository */
  69         if (has_sha1_file(oid->hash))
  70                 return 1;
  71
  72         /* Might want to keep the list sorted */
  73         for (i = 0; i < state->nr_written; i++)
  74                 if (!oidcmp(&state->written[i]->oid, oid))
  75                         return 1;
  76
  77         /* This is a new object we need to keep */
  78         return 0;
  79 }
  80
  81 /*
  82  * Read the contents from fd for size bytes, streaming it to the
  83  * packfile in state while updating the hash in ctx. Signal a failure
  84  * by returning a negative value when the resulting pack would exceed
  85  * the pack size limit and this is not the first object in the pack,
  86  * so that the caller can discard what we wrote from the current pack
  87  * by truncating it and opening a new one. The caller will then call
  88  * us again after rewinding the input fd.
  89  *
  90  * The already_hashed_to pointer is kept untouched by the caller to
  91  * make sure we do not hash the same byte when we are called
  92  * again. This way, the caller does not have to checkpoint its hash
  93  * status before calling us just in case we ask it to call us again
  94  * with a new pack.
  95  */
  96 static int stream_to_pack(struct bulk_checkin_state *state,
  97                           git_hash_ctx *ctx, off_t *already_hashed_to,
  98                           int fd, size_t size, enum object_type type,
  99                           const char *path, unsigned flags)
 100 {
 101         git_zstream s;
 102         unsigned char obuf[16384];
 103         unsigned hdrlen;
 104         int status = Z_OK;
 105         int write_object = (flags & HASH_WRITE_OBJECT);
 106         off_t offset = 0;
 107
 108         git_deflate_init(&s, pack_compression_level);
 109
 110         hdrlen = encode_in_pack_object_header(obuf, sizeof(obuf), type, size);
 111         s.next_out = obuf + hdrlen;
 112         s.avail_out = sizeof(obuf) - hdrlen;
 113
 114         while (status != Z_STREAM_END) {
 115                 unsigned char ibuf[16384];
 116
 117                 if (size && !s.avail_in) {
 118                         ssize_t rsize = size < sizeof(ibuf) ? size : sizeof(ibuf);
 119                         ssize_t read_result = read_in_full(fd, ibuf, rsize);
 120                         if (read_result < 0)
 121                                 die_errno("failed to read from '%s'", path);
 122                         if (read_result != rsize)
 123                                 die("failed to read %d bytes from '%s'",
 124                                     (int)rsize, path);
 125                         offset += rsize;
 126                         if (*already_hashed_to < offset) {
 127                                 size_t hsize = offset - *already_hashed_to;
 128                                 if (rsize < hsize)
 129                                         hsize = rsize;
 130                                 if (hsize)
 131                                         the_hash_algo->update_fn(ctx, ibuf, hsize);
 132                                 *already_hashed_to = offset;
 133                         }
 134                         s.next_in = ibuf;
 135                         s.avail_in = rsize;
 136                         size -= rsize;
 137                 }
 138
 139                 status = git_deflate(&s, size ? 0 : Z_FINISH);
 140
 141                 if (!s.avail_out || status == Z_STREAM_END) {
 142                         if (write_object) {
 143                                 size_t written = s.next_out - obuf;
 144
 145                                 /* would we bust the size limit? */
 146                                 if (state->nr_written &&
 147                                     pack_size_limit_cfg &&
 148                                     pack_size_limit_cfg < state->offset + written) {
 149                                         git_deflate_abort(&s);
 150                                         return -1;
 151                                 }
 152
 153                                 hashwrite(state->f, obuf, written);
 154                                 state->offset += written;
 155                         }
 156                         s.next_out = obuf;
 157                         s.avail_out = sizeof(obuf);
 158                 }
 159
 160                 switch (status) {
 161                 case Z_OK:
 162                 case Z_BUF_ERROR:
 163                 case Z_STREAM_END:
 164                         continue;
 165                 default:
 166                         die("unexpected deflate failure: %d", status);
 167                 }
 168         }
 169         git_deflate_end(&s);
 170         return 0;
 171 }
 172
 173 /* Lazily create backing packfile for the state */
 174 static void prepare_to_stream(struct bulk_checkin_state *state,
 175                               unsigned flags)
 176 {
 177         if (!(flags & HASH_WRITE_OBJECT) || state->f)
 178                 return;
 179
 180         state->f = create_tmp_packfile(&state->pack_tmp_name);
 181         reset_pack_idx_option(&state->pack_idx_opts);
 182
 183         /* Pretend we are going to write only one object */
 184         state->offset = write_pack_header(state->f, 1);
 185         if (!state->offset)
 186                 die_errno("unable to write pack header");
 187 }
 188
 189 static int deflate_to_pack(struct bulk_checkin_state *state,
 190                            struct object_id *result_oid,
 191                            int fd, size_t size,
 192                            enum object_type type, const char *path,
 193                            unsigned flags)
 194 {
 195         off_t seekback, already_hashed_to;
 196         git_hash_ctx ctx;
 197         unsigned char obuf[16384];
 198         unsigned header_len;
 199         struct hashfile_checkpoint checkpoint;
 200         struct pack_idx_entry *idx = NULL;
 201
 202         seekback = lseek(fd, 0, SEEK_CUR);
 203         if (seekback == (off_t) -1)
 204                 return error("cannot find the current offset");
 205
 206         header_len = xsnprintf((char *)obuf, sizeof(obuf), "%s %" PRIuMAX,
 207                                type_name(type), (uintmax_t)size) + 1;
 208         the_hash_algo->init_fn(&ctx);
 209         the_hash_algo->update_fn(&ctx, obuf, header_len);
 210
 211         /* Note: idx is non-NULL when we are writing */
 212         if ((flags & HASH_WRITE_OBJECT) != 0)
 213                 idx = xcalloc(1, sizeof(*idx));
 214
 215         already_hashed_to = 0;
 216
 217         while (1) {
 218                 prepare_to_stream(state, flags);
 219                 if (idx) {
 220                         hashfile_checkpoint(state->f, &checkpoint);
 221                         idx->offset = state->offset;
 222                         crc32_begin(state->f);
 223                 }
 224                 if (!stream_to_pack(state, &ctx, &already_hashed_to,
 225                                     fd, size, type, path, flags))
 226                         break;
 227                 /*
 228                  * Writing this object to the current pack will make
 229                  * it too big; we need to truncate it, start a new
 230                  * pack, and write into it.
 231                  */
 232                 if (!idx)
 233                         die("BUG: should not happen");
 234                 hashfile_truncate(state->f, &checkpoint);
 235                 state->offset = checkpoint.offset;
 236                 finish_bulk_checkin(state);
 237                 if (lseek(fd, seekback, SEEK_SET) == (off_t) -1)
 238                         return error("cannot seek back");
 239         }
 240         the_hash_algo->final_fn(result_oid->hash, &ctx);
 241         if (!idx)
 242                 return 0;
 243
 244         idx->crc32 = crc32_end(state->f);
 245         if (already_written(state, result_oid)) {
 246                 hashfile_truncate(state->f, &checkpoint);
 247                 state->offset = checkpoint.offset;
 248                 free(idx);
 249         } else {
 250                 oidcpy(&idx->oid, result_oid);
 251                 ALLOC_GROW(state->written,
 252                            state->nr_written + 1,
 253                            state->alloc_written);
 254                 state->written[state->nr_written++] = idx;
 255         }
 256         return 0;
 257 }
 258
 259 int index_bulk_checkin(struct object_id *oid,
 260                        int fd, size_t size, enum object_type type,
 261                        const char *path, unsigned flags)
 262 {
 263         int status = deflate_to_pack(&state, oid, fd, size, type,
 264                                      path, flags);
 265         if (!state.plugged)
 266                 finish_bulk_checkin(&state);
 267         return status;
 268 }
 269
 270 void plug_bulk_checkin(void)
 271 {
 272         state.plugged = 1;
 273 }
 274
 275 void unplug_bulk_checkin(void)
 276 {
 277         state.plugged = 0;
 278         if (state.f)
 279                 finish_bulk_checkin(&state);
 280 }