Re: [PATCH v2 5/6] reftable/stack: allow passing flags to `reftable_stack_add()`

> The `reftable_stack_add()` function is a simple wrapper to lock the
> stack, add records to it via a callback and then commit the
> result. One problem with it though is that it doesn't accept any flags
> for creating the addition. This makes it impossible to automatically
> reload the stack in case it was modified before we managed to lock the
> stack.
> 
> Add a `flags` field to plug this gap and pass it through accordingly.
> For now this new flag won't be used by us, but it will be used by
> libgit2.
> 
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  refs/reftable-backend.c         |  8 +++----
>  reftable/reftable-stack.h       |  9 +++++---
>  reftable/stack.c                |  8 +++----
>  t/unit-tests/t-reftable-stack.c | 50 ++++++++++++++++++++---------------------
>  4 files changed, 39 insertions(+), 36 deletions(-)
> 

> diff --git a/reftable/reftable-stack.h b/reftable/reftable-stack.h
> index 910ec6ef3a2..d70fcb705dc 100644
> --- a/reftable/reftable-stack.h
> +++ b/reftable/reftable-stack.h
> @@ -68,12 +68,15 @@ int reftable_addition_commit(struct reftable_addition *add);
>   * transaction. Releases the lock if held. */
>  void reftable_addition_destroy(struct reftable_addition *add);
>  
> -/* add a new table to the stack. The write_table function must call
> - * reftable_writer_set_limits, add refs and return an error value. */
> +/*
> + * Add a new table to the stack. The write_table function must call
> + * reftable_writer_set_limits, add refs and return an error value.
> + * The flags are passed through to `reftable_stack_new_addition()`.
> + */
>  int reftable_stack_add(struct reftable_stack *st,
>  		       int (*write_table)(struct reftable_writer *wr,
>  					  void *write_arg),
> -		       void *write_arg);
> +		       void *write_arg, unsigned flags);
>  
>  struct reftable_iterator;
>  
> diff --git a/reftable/stack.c b/reftable/stack.c
> index d6e4ea93a37..f77d7f58e8e 100644
> --- a/reftable/stack.c
> +++ b/reftable/stack.c
> @@ -737,10 +737,10 @@ static int reftable_stack_init_addition(struct reftable_addition *add,
>  static int stack_try_add(struct reftable_stack *st,
>  			 int (*write_table)(struct reftable_writer *wr,
>  					    void *arg),
> -			 void *arg)
> +			 void *arg, unsigned flags)
>  {
>  	struct reftable_addition add = REFTABLE_ADDITION_INIT;
> -	int err = reftable_stack_init_addition(&add, st, 0);
> +	int err = reftable_stack_init_addition(&add, st, flags);