I'm in my next attempt to get through your patch series. Sorry for the
long hiatus.
Patches 1-19 look OK aside from a minor typo that I just reported.
See below for a comment on this patch.
On 06/20/2014 04:43 PM, Ronnie Sahlberg wrote:
> Do basic error checking in ref_transaction_create() and make it return
> non-zero on error. Update all callers to check the result of
> ref_transaction_create(). There are currently no conditions in _create that
> will return error but there will be in the future. Add an err argument that
> will be updated on failure.
>
> Reviewed-by: Jonathan Nieder <jrnie...@gmail.com>
> Signed-off-by: Ronnie Sahlberg <sahlb...@google.com>
> ---
> builtin/update-ref.c | 4 +++-
> refs.c | 18 +++++++++++------
> refs.h | 55
> +++++++++++++++++++++++++++++++++++++++++++++-------
> 3 files changed, 63 insertions(+), 14 deletions(-)
>
> diff --git a/builtin/update-ref.c b/builtin/update-ref.c
> index 3067b11..41121fa 100644
> --- a/builtin/update-ref.c
> +++ b/builtin/update-ref.c
> @@ -226,7 +226,9 @@ static const char *parse_cmd_create(struct strbuf *input,
> const char *next)
> if (*next != line_termination)
> die("create %s: extra input: %s", refname, next);
>
> - ref_transaction_create(transaction, refname, new_sha1, update_flags);
> + if (ref_transaction_create(transaction, refname, new_sha1,
> + update_flags, &err))
> + die("%s", err.buf);
>
> update_flags = 0;
> free(refname);
> diff --git a/refs.c b/refs.c
> index 3f05e88..c49f1c6 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -3449,18 +3449,24 @@ int ref_transaction_update(struct ref_transaction
> *transaction,
> return 0;
> }
>
> -void ref_transaction_create(struct ref_transaction *transaction,
> - const char *refname,
> - const unsigned char *new_sha1,
> - int flags)
> +int ref_transaction_create(struct ref_transaction *transaction,
> + const char *refname,
> + const unsigned char *new_sha1,
> + int flags,
> + struct strbuf *err)
> {
> - struct ref_update *update = add_update(transaction, refname);
> + struct ref_update *update;
> +
> + if (!new_sha1 || is_null_sha1(new_sha1))
> + die("BUG: create ref with null new_sha1");
> +
> + update = add_update(transaction, refname);
>
> - assert(!is_null_sha1(new_sha1));
> hashcpy(update->new_sha1, new_sha1);
> hashclr(update->old_sha1);
> update->flags = flags;
> update->have_old = 1;
> + return 0;
> }
>
> void ref_transaction_delete(struct ref_transaction *transaction,
> diff --git a/refs.h b/refs.h
> index c5376ce..33b4383 100644
> --- a/refs.h
> +++ b/refs.h
> @@ -10,6 +10,45 @@ struct ref_lock {
> int force_write;
> };
>
> +/*
> + * A ref_transaction represents a collection of ref updates
> + * that should succeed or fail together.
> + *
> + * Calling sequence
> + * ----------------
> + * - Allocate and initialize a `struct ref_transaction` by calling
> + * `ref_transaction_begin()`.
> + *
> + * - List intended ref updates by calling functions like
> + * `ref_transaction_update()` and `ref_transaction_create()`.
> + *
> + * - Call `ref_transaction_commit()` to execute the transaction.
> + * If this succeeds, the ref updates will have taken place and
> + * the transaction cannot be rolled back.
> + *
> + * - At any time call `ref_transaction_free()` to discard the
> + * transaction and free associated resources. In particular,
> + * this rolls back the transaction if it has not been
> + * successfully committed.
> + *
> + * Error handling
> + * --------------
> + *
> + * On error, transaction functions append a message about what
> + * went wrong to the 'err' argument. The message mentions what
> + * ref was being updated (if any) when the error occurred so it
> + * can be passed to 'die' or 'error' as-is.
> + *
> + * The message is appended to err without first clearing err.
> + * This allows the caller to prepare preamble text to the generated
> + * error message:
> + *
> + * strbuf_addf(&err, "Error while doing foo-bar: ");
> + * if (ref_transaction_update(..., &err)) {
> + * ret = error("%s", err.buf);
> + * goto cleanup;
> + * }
> + */
I don't have a problem with the API, but I think the idiom suggested in
the comment above is a bit silly. Surely one would do the following
instead:
if (ref_transaction_update(..., &err)) {
ret = error("Error while doing foo-bar: %s", err.buf);
goto cleanup;
}
I think it would also be helpful to document whether the error string
that is appended to the strbuf is terminated with a LF.
> [...]
Michael
--
Michael Haggerty
mhag...@alum.mit.edu
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