Re: [PATCH v20 23/48] refs.c: add transaction.status and track OPEN/CLOSED/ERROR

[Michael Haggerty <mhagger@alum.mit.edu>]

On 06/20/2014 04:43 PM, Ronnie Sahlberg wrote:
> Track the status of a transaction in a new status field. Check the field for

The status field is not set or used anywhere.  The field that you use is
"state".

> sanity, i.e. that status must be OPEN when _commit/_create/_delete or
> _update is called or else die(BUG:...)
> 
> Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
> ---
>  refs.c | 40 +++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 39 insertions(+), 1 deletion(-)
> 
> diff --git a/refs.c b/refs.c
> index 9cb7908..8c695ba 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -3387,6 +3387,25 @@ struct ref_update {
>  };
>  
>  /*
> + * Transaction states.
> + * OPEN:   The transaction is in a valid state and can accept new updates.
> + *         An OPEN transaction can be committed.
> + * CLOSED: If an open transaction is successfully committed the state will
> + *         change to CLOSED. No further changes can be made to a CLOSED
> + *         transaction.
> + *         CLOSED means that all updates have been successfully committed and
> + *         the only thing that remains is to free the completed transaction.
> + * ERROR:  The transaction has failed and is no longer committable.
> + *         No further changes can be made to a CLOSED transaction and it must
> + *         be rolled back using transaction_free.
> + */
> +enum ref_transaction_state {
> +	REF_TRANSACTION_OPEN   = 0,
> +	REF_TRANSACTION_CLOSED = 1,
> +	REF_TRANSACTION_ERROR  = 2,
> +};
> +
> +/*
>   * Data structure for holding a reference transaction, which can
>   * consist of checks and updates to multiple references, carried out
>   * as atomically as possible.  This structure is opaque to callers.
> @@ -3395,6 +3414,8 @@ struct ref_transaction {
>  	struct ref_update **updates;
>  	size_t alloc;
>  	size_t nr;
> +	enum ref_transaction_state state;
> +	int status;

The status field should probably be deleted.

>  };
>  
>  struct ref_transaction *ref_transaction_begin(struct strbuf *err)
> @@ -3437,6 +3458,9 @@ int ref_transaction_update(struct ref_transaction *transaction,
>  {
>  	struct ref_update *update;
>  
> +	if (transaction->state != REF_TRANSACTION_OPEN)
> +		die("BUG: update called for transaction that is not open");
> +
>  	if (have_old && !old_sha1)
>  		die("BUG: have_old is true but old_sha1 is NULL");
>  
> @@ -3457,6 +3481,9 @@ int ref_transaction_create(struct ref_transaction *transaction,
>  {
>  	struct ref_update *update;
>  
> +	if (transaction->state != REF_TRANSACTION_OPEN)
> +		die("BUG: create called for transaction that is not open");
> +
>  	if (!new_sha1 || is_null_sha1(new_sha1))
>  		die("BUG: create ref with null new_sha1");
>  
> @@ -3477,6 +3504,9 @@ int ref_transaction_delete(struct ref_transaction *transaction,
>  {
>  	struct ref_update *update;
>  
> +	if (transaction->state != REF_TRANSACTION_OPEN)
> +		die("BUG: delete called for transaction that is not open");
> +
>  	if (have_old && !old_sha1)
>  		die("BUG: have_old is true but old_sha1 is NULL");
>  
> @@ -3532,8 +3562,13 @@ int ref_transaction_commit(struct ref_transaction *transaction,
>  	int n = transaction->nr;
>  	struct ref_update **updates = transaction->updates;
>  
> -	if (!n)
> +	if (transaction->state != REF_TRANSACTION_OPEN)
> +		die("BUG: commit called for transaction that is not open");
> +
> +	if (!n) {
> +		transaction->state = REF_TRANSACTION_CLOSED;
>  		return 0;
> +	}
>  
>  	/* Allocate work space */
>  	delnames = xmalloc(sizeof(*delnames) * n);
> @@ -3595,6 +3630,9 @@ int ref_transaction_commit(struct ref_transaction *transaction,
>  	clear_loose_ref_cache(&ref_cache);
>  
>  cleanup:
> +	transaction->state = ret ? REF_TRANSACTION_ERROR
> +		: REF_TRANSACTION_CLOSED;
> +
>  	for (i = 0; i < n; i++)
>  		if (updates[i]->lock)
>  			unlock_ref(updates[i]->lock);
> 


-- 
Michael Haggerty
mhagger@alum.mit.edu
http://softwareswirl.blogspot.com/