From: Junio C Hamano <gitster@pobox.com>
To: Jacob Keller <jacob.e.keller@intel.com>
Cc: git@vger.kernel.org, Stefan Beller <stefanbeller@gmail.com>,
Jeff King <peff@peff.net>, Johannes Sixt <j6t@kdbg.org>,
Jacob Keller <jacob.keller@gmail.com>
Subject: Re: [PATCH v8 7/8] cache: add empty_tree_oid object
Date: Fri, 19 Aug 2016 13:31:27 -0700 [thread overview]
Message-ID: <xmqqfuq01oww.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <20160819000031.24854-8-jacob.e.keller@intel.com> (Jacob Keller's message of "Thu, 18 Aug 2016 17:00:30 -0700")
Jacob Keller <jacob.e.keller@intel.com> writes:
> From: Jacob Keller <jacob.keller@gmail.com>
>
> Add an empty_tree_oid object which can be used in place of
> EMPTY_TREE_SHA1_BIN_LITERAL for code which is being converted to struct
> object_id.
How widely do you envision the users of this symbol would be spread
across the entire codebase? I am debating myself if we need a
singleton in-core copy like this (if we end up referring to it from
everywhere), or we only need one level higher abstraction,
e.g. "is_empty_tree_oid()" helper (in which case I do not think we
even need a singleton; just imitate how is_empty_blob_sha1() is
implemented).
Even if we need such a singleton, I think we avoid ".field = value"
struct initializations in our code.
>
> Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
> ---
> cache.h | 2 ++
> sha1_file.c | 3 +++
> 2 files changed, 5 insertions(+)
>
> diff --git a/cache.h b/cache.h
> index f30a4417efdf..da9f0be67d7b 100644
> --- a/cache.h
> +++ b/cache.h
> @@ -964,6 +964,8 @@ static inline void oidclr(struct object_id *oid)
> #define EMPTY_BLOB_SHA1_BIN \
> ((const unsigned char *) EMPTY_BLOB_SHA1_BIN_LITERAL)
>
> +extern const struct object_id empty_tree_oid;
> +
> static inline int is_empty_blob_sha1(const unsigned char *sha1)
> {
> return !hashcmp(sha1, EMPTY_BLOB_SHA1_BIN);
> diff --git a/sha1_file.c b/sha1_file.c
> index 1e23fc186a02..10883d56a600 100644
> --- a/sha1_file.c
> +++ b/sha1_file.c
> @@ -38,6 +38,9 @@ static inline uintmax_t sz_fmt(size_t s) { return s; }
>
> const unsigned char null_sha1[20];
> const struct object_id null_oid;
> +const struct object_id empty_tree_oid = {
> + .hash = EMPTY_TREE_SHA1_BIN_LITERAL
> +};
>
> /*
> * This is meant to hold a *small* number of objects that you would
next prev parent reply other threads:[~2016-08-19 20:34 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-19 0:00 [PATCH v8 0/8] submodule show inline diff Jacob Keller
2016-08-19 0:00 ` [PATCH v8 1/8] diff.c: remove output_prefix_length field Jacob Keller
2016-08-19 0:00 ` [PATCH v8 2/8] graph: add support for --line-prefix on all graph-aware output Jacob Keller
2016-08-19 0:00 ` [PATCH v8 3/8] diff: prepare for additional submodule formats Jacob Keller
2016-08-19 19:49 ` Junio C Hamano
2016-08-19 0:00 ` [PATCH v8 4/8] submodule: allow add_submodule_odb to work even if path is not checked out Jacob Keller
2016-08-19 20:06 ` Junio C Hamano
2016-08-19 20:32 ` Jacob Keller
2016-08-19 21:11 ` Junio C Hamano
2016-08-19 22:00 ` Jacob Keller
2016-08-19 22:26 ` Junio C Hamano
2016-08-19 23:25 ` Jacob Keller
2016-08-19 0:00 ` [PATCH v8 5/8] submodule: convert show_submodule_summary to use struct object_id * Jacob Keller
2016-08-19 20:12 ` Junio C Hamano
2016-08-19 0:00 ` [PATCH v8 6/8] submodule: refactor show_submodule_summary with helper function Jacob Keller
2016-08-19 20:24 ` Junio C Hamano
2016-08-19 20:33 ` Jacob Keller
2016-08-19 0:00 ` [PATCH v8 7/8] cache: add empty_tree_oid object Jacob Keller
2016-08-19 20:31 ` Junio C Hamano [this message]
2016-08-19 20:35 ` Jacob Keller
2016-08-19 20:50 ` Junio C Hamano
2016-08-19 21:14 ` Junio C Hamano
2016-08-19 22:02 ` Jacob Keller
2016-08-19 20:58 ` Jeff King
2016-08-23 16:28 ` Junio C Hamano
2016-08-19 0:00 ` [PATCH v8 8/8] diff: teach diff to display submodule difference with an inline diff Jacob Keller
2016-08-19 21:52 ` Junio C Hamano
2016-08-19 22:03 ` Jacob Keller
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