Re: [PATCH v8 17/44] fast-import.c: change update_branch to use ref transactions
flat view
From: Jonathan Nieder <hidden>
Date: 2016-06-15 23:01:11
Ronnie Sahlberg wrote:
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--- a/fast-import.c +++ b/fast-import.c@@ -1679,39 +1679,45 @@ found_entry: static int update_branch(struct branch *b) { static const char *msg = "fast-import"; - struct ref_lock *lock; + struct ref_transaction *transaction; unsigned char old_sha1[20]; + struct strbuf err = STRBUF_INIT; if (read_ref(b->name, old_sha1)) hashclr(old_sha1); + if (is_null_sha1(b->sha1)) { if (b->delete) delete_ref(b->name, old_sha1, 0); return 0; } - lock = lock_any_ref_for_update(b->name, old_sha1, 0, NULL); - if (!lock) - return error("Unable to lock %s", b->name); if (!force_update && !is_null_sha1(old_sha1)) { struct commit *old_cmit, *new_cmit; old_cmit = lookup_commit_reference_gently(old_sha1, 0); new_cmit = lookup_commit_reference_gently(b->sha1, 0); if (!old_cmit || !new_cmit) { - unlock_ref(lock); return error("Branch %s is missing commits.", b->name); }
(style) Now that there's only one line in the "if" body, we can drop the braces.
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if (!in_merge_bases(old_cmit, new_cmit)) { - unlock_ref(lock); warning("Not updating %s" " (new tip %s does not contain %s)", b->name, sha1_to_hex(b->sha1), sha1_to_hex(old_sha1)); return -1;
(not about this patch, feel free to ignore) This could
return warning("...")
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} - if (write_ref_sha1(lock, b->sha1, msg) < 0) - return error("Unable to update %s", b->name); + transaction = ref_transaction_begin(); + if ((!transaction || + ref_transaction_update(transaction, b->name, b->sha1, old_sha1, + 0, 1)) ||
Would be more idiomatic to drop a layer of parentheses: if (!transaction || ref_transaction_update(...) ||
+ (ref_transaction_commit(transaction, msg, &err) &&
+ !(transaction = NULL))) {Would be clearer if ref_transaction_commit didn't take care of the rollback (or in other words if patch 21 were earlier in the series).
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+ ref_transaction_rollback(transaction); + error("Unable to update branch %s: %s", b->name, err.buf); + strbuf_release(&err); + return -1; + }
Example old message:
error: Unable to lock refs/heads/master
New message:
error: Unable to update branch refs/heads/master: Cannot lock the ref 'refs/heads/master'.
So 'error("%s", err.buf)' would probably work better.
The only call site is dump_branches:
for (i = 0; i < branch_table_sz; i++) {
for (b = branch_table[i]; b; b = b->table_next_branch)
failure |= update_branch(b);
}
Should these happen in a single transaction? I haven't thought
through whether it would be a good idea, if it should be optional, or
what.
Anyway, that would be a bigger behavior change, but it's interesting
to think about.
Thanks,
Jonathan