On Tue, May 13, 2014 at 1:15 PM, Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx> wrote:
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
> ---
> Documentation/config.txt | 4 ++++
> cache.h | 1 +
> config.c | 12 ++++++++++++
> environment.c | 1 +
> read-cache.c | 43 +++++++++++++++++++++++++++++++++++++++++++
> submodule.c | 1 +
> 6 files changed, 62 insertions(+)
>
> diff --git a/Documentation/config.txt b/Documentation/config.txt
> index d8b6cc9..ccbe00b 100644
> --- a/Documentation/config.txt
> +++ b/Documentation/config.txt
> @@ -617,6 +617,10 @@ relatively high IO latencies. With this set to 'true', Git will do the
> index comparison to the filesystem data in parallel, allowing
> overlapping IO's.
>
> +core.useReadCacheDaemon::
> + Use `git read-cache--daemon` to speed up index reading. See
> + linkgit:git-read-cache--daemon for more information.
> +
> core.createObject::
> You can set this to 'link', in which case a hardlink followed by
> a delete of the source are used to make sure that object creation
> diff --git a/cache.h b/cache.h
> index d0ff11c..fb29c7e 100644
> --- a/cache.h
> +++ b/cache.h
> @@ -603,6 +603,7 @@ extern size_t packed_git_limit;
> extern size_t delta_base_cache_limit;
> extern unsigned long big_file_threshold;
> extern unsigned long pack_size_limit_cfg;
> +extern int use_read_cache_daemon;
>
> /*
> * Do replace refs need to be checked this run? This variable is
> diff --git a/config.c b/config.c
> index a30cb5c..5c832ad 100644
> --- a/config.c
> +++ b/config.c
> @@ -874,6 +874,18 @@ static int git_default_core_config(const char *var, const char *value)
> return 0;
> }
>
> +#ifdef HAVE_SHM
> + /*
> + * Currently git-read-cache--daemon is only built when
> + * HAVE_SHM is set. Ignore user settings if HAVE_SHM is not
> + * defined.
> + */
> + if (!strcmp(var, "core.usereadcachedaemon")) {
> + use_read_cache_daemon = git_config_bool(var, value);
> + return 0;
> + }
> +#endif
> +
> /* Add other config variables here and to Documentation/config.txt. */
> return 0;
> }
> diff --git a/environment.c b/environment.c
> index 5c4815d..b76a414 100644
> --- a/environment.c
> +++ b/environment.c
> @@ -63,6 +63,7 @@ int merge_log_config = -1;
> int precomposed_unicode = -1; /* see probe_utf8_pathname_composition() */
> struct startup_info *startup_info;
> unsigned long pack_size_limit_cfg;
> +int use_read_cache_daemon;
>
> /*
> * The character that begins a commented line in user-editable file
> diff --git a/read-cache.c b/read-cache.c
> index a5031f3..0e46523 100644
> --- a/read-cache.c
> +++ b/read-cache.c
> @@ -1462,6 +1462,48 @@ static struct cache_entry *create_from_disk(struct ondisk_cache_entry *ondisk,
> return ce;
> }
>
> +static void *try_shm(void *mmap, size_t *mmap_size)
> +{
> + struct strbuf sb = STRBUF_INIT;
> + size_t old_size = *mmap_size;
> + void *new_mmap;
> + struct stat st;
> + int fd;
> +
> + if (old_size <= 20 || !use_read_cache_daemon)
> + return mmap;
> +
> + strbuf_addf(&sb, "/git-index-%s.lock",
> + sha1_to_hex((unsigned char *)mmap + old_size - 20));
> + fd = shm_open(sb.buf, O_RDONLY, 0777);
OK, so *here* you do an unguarded use of shm_open, but the code never
gets executed because of the HAVE_SHM guard in
git_default_core_config. Perhaps not introduce the compatibility shim
until this patch, then?
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