in read-cache.c [2829:3133]
static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
enum write_extensions write_extensions, unsigned flags)
{
uint64_t start = getnanotime();
struct hashfile *f;
struct git_hash_ctx *eoie_c = NULL;
struct cache_header hdr;
int i, err = 0, removed, extended, hdr_version;
struct cache_entry **cache = istate->cache;
int entries = istate->cache_nr;
struct stat st;
struct ondisk_cache_entry ondisk;
struct strbuf previous_name_buf = STRBUF_INIT, *previous_name;
int drop_cache_tree = istate->drop_cache_tree;
off_t offset;
int csum_fsync_flag;
int ieot_entries = 1;
struct index_entry_offset_table *ieot = NULL;
struct repository *r = istate->repo;
struct strbuf sb = STRBUF_INIT;
int nr, nr_threads, ret;
f = hashfd(the_repository->hash_algo, tempfile->fd, tempfile->filename.buf);
prepare_repo_settings(r);
f->skip_hash = r->settings.index_skip_hash;
for (i = removed = extended = 0; i < entries; i++) {
if (cache[i]->ce_flags & CE_REMOVE)
removed++;
/* reduce extended entries if possible */
cache[i]->ce_flags &= ~CE_EXTENDED;
if (cache[i]->ce_flags & CE_EXTENDED_FLAGS) {
extended++;
cache[i]->ce_flags |= CE_EXTENDED;
}
}
if (!istate->version)
istate->version = get_index_format_default(r);
/* demote version 3 to version 2 when the latter suffices */
if (istate->version == 3 || istate->version == 2)
istate->version = extended ? 3 : 2;
hdr_version = istate->version;
hdr.hdr_signature = htonl(CACHE_SIGNATURE);
hdr.hdr_version = htonl(hdr_version);
hdr.hdr_entries = htonl(entries - removed);
hashwrite(f, &hdr, sizeof(hdr));
if (!HAVE_THREADS || repo_config_get_index_threads(the_repository, &nr_threads))
nr_threads = 1;
if (nr_threads != 1 && record_ieot()) {
int ieot_blocks, cpus;
/*
* ensure default number of ieot blocks maps evenly to the
* default number of threads that will process them leaving
* room for the thread to load the index extensions.
*/
if (!nr_threads) {
ieot_blocks = istate->cache_nr / THREAD_COST;
cpus = online_cpus();
if (ieot_blocks > cpus - 1)
ieot_blocks = cpus - 1;
} else {
ieot_blocks = nr_threads;
if (ieot_blocks > istate->cache_nr)
ieot_blocks = istate->cache_nr;
}
/*
* no reason to write out the IEOT extension if we don't
* have enough blocks to utilize multi-threading
*/
if (ieot_blocks > 1) {
ieot = xcalloc(1, sizeof(struct index_entry_offset_table)
+ (ieot_blocks * sizeof(struct index_entry_offset)));
ieot_entries = DIV_ROUND_UP(entries, ieot_blocks);
}
}
offset = hashfile_total(f);
nr = 0;
previous_name = (hdr_version == 4) ? &previous_name_buf : NULL;
for (i = 0; i < entries; i++) {
struct cache_entry *ce = cache[i];
if (ce->ce_flags & CE_REMOVE)
continue;
if (!ce_uptodate(ce) && is_racy_timestamp(istate, ce))
ce_smudge_racily_clean_entry(istate, ce);
if (is_null_oid(&ce->oid)) {
static const char msg[] = "cache entry has null sha1: %s";
static int allow = -1;
if (allow < 0)
allow = git_env_bool("GIT_ALLOW_NULL_SHA1", 0);
if (allow)
warning(msg, ce->name);
else
err = error(msg, ce->name);
drop_cache_tree = 1;
}
if (ieot && i && (i % ieot_entries == 0)) {
ieot->entries[ieot->nr].nr = nr;
ieot->entries[ieot->nr].offset = offset;
ieot->nr++;
/*
* If we have a V4 index, set the first byte to an invalid
* character to ensure there is nothing common with the previous
* entry
*/
if (previous_name)
previous_name->buf[0] = 0;
nr = 0;
offset = hashfile_total(f);
}
if (ce_write_entry(f, ce, previous_name, (struct ondisk_cache_entry *)&ondisk) < 0)
err = -1;
if (err)
break;
nr++;
}
if (ieot && nr) {
ieot->entries[ieot->nr].nr = nr;
ieot->entries[ieot->nr].offset = offset;
ieot->nr++;
}
strbuf_release(&previous_name_buf);
if (err) {
ret = err;
goto out;
}
offset = hashfile_total(f);
/*
* The extension headers must be hashed on their own for the
* EOIE extension. Create a hashfile here to compute that hash.
*/
if (offset && record_eoie()) {
CALLOC_ARRAY(eoie_c, 1);
the_hash_algo->init_fn(eoie_c);
}
/*
* Lets write out CACHE_EXT_INDEXENTRYOFFSETTABLE first so that we
* can minimize the number of extensions we have to scan through to
* find it during load. Write it out regardless of the
* strip_extensions parameter as we need it when loading the shared
* index.
*/
if (ieot) {
strbuf_reset(&sb);
write_ieot_extension(&sb, ieot);
err = write_index_ext_header(f, eoie_c, CACHE_EXT_INDEXENTRYOFFSETTABLE, sb.len) < 0;
hashwrite(f, sb.buf, sb.len);
if (err) {
ret = -1;
goto out;
}
}
if (write_extensions & WRITE_SPLIT_INDEX_EXTENSION &&
istate->split_index) {
strbuf_reset(&sb);
if (istate->sparse_index)
die(_("cannot write split index for a sparse index"));
err = write_link_extension(&sb, istate) < 0 ||
write_index_ext_header(f, eoie_c, CACHE_EXT_LINK,
sb.len) < 0;
hashwrite(f, sb.buf, sb.len);
if (err) {
ret = -1;
goto out;
}
}
if (write_extensions & WRITE_CACHE_TREE_EXTENSION &&
!drop_cache_tree && istate->cache_tree) {
strbuf_reset(&sb);
cache_tree_write(&sb, istate->cache_tree);
err = write_index_ext_header(f, eoie_c, CACHE_EXT_TREE, sb.len) < 0;
hashwrite(f, sb.buf, sb.len);
if (err) {
ret = -1;
goto out;
}
}
if (write_extensions & WRITE_RESOLVE_UNDO_EXTENSION &&
istate->resolve_undo) {
strbuf_reset(&sb);
resolve_undo_write(&sb, istate->resolve_undo, the_hash_algo);
err = write_index_ext_header(f, eoie_c, CACHE_EXT_RESOLVE_UNDO,
sb.len) < 0;
hashwrite(f, sb.buf, sb.len);
if (err) {
ret = -1;
goto out;
}
}
if (write_extensions & WRITE_UNTRACKED_CACHE_EXTENSION &&
istate->untracked) {
strbuf_reset(&sb);
write_untracked_extension(&sb, istate->untracked);
err = write_index_ext_header(f, eoie_c, CACHE_EXT_UNTRACKED,
sb.len) < 0;
hashwrite(f, sb.buf, sb.len);
if (err) {
ret = -1;
goto out;
}
}
if (write_extensions & WRITE_FSMONITOR_EXTENSION &&
istate->fsmonitor_last_update) {
strbuf_reset(&sb);
write_fsmonitor_extension(&sb, istate);
err = write_index_ext_header(f, eoie_c, CACHE_EXT_FSMONITOR, sb.len) < 0;
hashwrite(f, sb.buf, sb.len);
if (err) {
ret = -1;
goto out;
}
}
if (istate->sparse_index) {
if (write_index_ext_header(f, eoie_c, CACHE_EXT_SPARSE_DIRECTORIES, 0) < 0) {
ret = -1;
goto out;
}
}
/*
* CACHE_EXT_ENDOFINDEXENTRIES must be written as the last entry before the SHA1
* so that it can be found and processed before all the index entries are
* read. Write it out regardless of the strip_extensions parameter as we need it
* when loading the shared index.
*/
if (eoie_c) {
strbuf_reset(&sb);
write_eoie_extension(&sb, eoie_c, offset);
err = write_index_ext_header(f, NULL, CACHE_EXT_ENDOFINDEXENTRIES, sb.len) < 0;
hashwrite(f, sb.buf, sb.len);
if (err) {
ret = -1;
goto out;
}
}
csum_fsync_flag = 0;
if (!alternate_index_output && (flags & COMMIT_LOCK))
csum_fsync_flag = CSUM_FSYNC;
finalize_hashfile(f, istate->oid.hash, FSYNC_COMPONENT_INDEX,
CSUM_HASH_IN_STREAM | csum_fsync_flag);
f = NULL;
if (close_tempfile_gently(tempfile)) {
ret = error(_("could not close '%s'"), get_tempfile_path(tempfile));
goto out;
}
if (stat(get_tempfile_path(tempfile), &st)) {
ret = -1;
goto out;
}
istate->timestamp.sec = (unsigned int)st.st_mtime;
istate->timestamp.nsec = ST_MTIME_NSEC(st);
trace_performance_since(start, "write index, changed mask = %x", istate->cache_changed);
/*
* TODO trace2: replace "the_repository" with the actual repo instance
* that is associated with the given "istate".
*/
trace2_data_intmax("index", the_repository, "write/version",
istate->version);
trace2_data_intmax("index", the_repository, "write/cache_nr",
istate->cache_nr);
ret = 0;
out:
if (f)
free_hashfile(f);
strbuf_release(&sb);
free(eoie_c);
free(ieot);
return ret;
}