Re: [PATCH v2 06/10] preload-index.c: remove #ifdef NO_PTHREADS

[Ben Peart <peartben@gmail.com>]

On 10/27/2018 1:30 PM, Nguyễn Thái Ngọc Duy wrote:
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
>   preload-index.c | 15 ++-------------
>   1 file changed, 2 insertions(+), 13 deletions(-)
> 
> diff --git a/preload-index.c b/preload-index.c
> index 9e7152ab14..0e24886aca 100644
> --- a/preload-index.c
> +++ b/preload-index.c
> @@ -7,17 +7,7 @@
>   #include "fsmonitor.h"
>   #include "config.h"
>   #include "progress.h"
> -
> -#ifdef NO_PTHREADS
> -static void preload_index(struct index_state *index,
> -			  const struct pathspec *pathspec,
> -			  unsigned int refresh_flags)
> -{
> -	; /* nothing */
> -}
> -#else
> -
> -#include <pthread.h>
> +#include "thread-utils.h"
>   
>   /*
>    * Mostly randomly chosen maximum thread counts: we
> @@ -108,7 +98,7 @@ static void preload_index(struct index_state *index,
>   	struct thread_data data[MAX_PARALLEL];
>   	struct progress_data pd;
>   
> -	if (!core_preload_index)
> +	if (!HAVE_THREADS || !core_preload_index)
>   		return;
>   
>   	threads = index->cache_nr / THREAD_COST;
> @@ -151,7 +141,6 @@ static void preload_index(struct index_state *index,
>   
>   	trace_performance_leave("preload index");
>   }
> -#endif
>   
>   int read_index_preload(struct index_state *index,
>   		       const struct pathspec *pathspec,
> 


In the theory that code speaks louder than comments, here is the patch I 
used when testing out the idea of getting rid of NO_PTHREADS:


  git diff head~1 preload-index.c
diff --git a/preload-index.c b/preload-index.c
index 9e7152ab14..266bc9d8d7 100644
--- a/preload-index.c
+++ b/preload-index.c
@@ -7,17 +7,7 @@
  #include "fsmonitor.h"
  #include "config.h"
  #include "progress.h"
-
-#ifdef NO_PTHREADS
-static void preload_index(struct index_state *index,
-                         const struct pathspec *pathspec,
-                         unsigned int refresh_flags)
-{
-       ; /* nothing */
-}
-#else
-
-#include <pthread.h>
+#include "thread-utils.h"

  /*
   * Mostly randomly chosen maximum thread counts: we
@@ -104,7 +94,7 @@ static void preload_index(struct index_state *index,
                           const struct pathspec *pathspec,
                           unsigned int refresh_flags)
  {
-       int threads, i, work, offset;
+       int cpus, threads, i, work, offset;
         struct thread_data data[MAX_PARALLEL];
         struct progress_data pd;

@@ -114,6 +104,9 @@ static void preload_index(struct index_state *index,
         threads = index->cache_nr / THREAD_COST;
         if ((index->cache_nr > 1) && (threads < 2) && 
git_env_bool("GIT_TEST_PRELOAD_INDEX", 0))
                 threads = 2;
+       cpus = online_cpus();
+       if (threads > cpus)
+               threads = cpus;
         if (threads < 2)
                 return;
         trace_performance_enter();
@@ -151,7 +144,6 @@ static void preload_index(struct index_state *index,

         trace_performance_leave("preload index");
  }
-#endif

  int read_index_preload(struct index_state *index,
                        const struct pathspec *pathspec,