[PATCH] Add support for changing packed_git_window_size at process start time

["R. Tyler Ballance" <tyler@slide.com>]

"Works" insofar that it will alter the packed_git_window_size variable in environment.c
when the environment is set up. It /doesn't/ work when commands like git-diff(1) and git-log(1)
call get_revision() which seems to disregard the setting if the packed_window_size is set to something
low (i.e. ulimit -v 32768)

Signed-off-by: R. Tyler Ballance <tyler@slide.com>
---
 environment.c     |   10 ++++++++++
 git-compat-util.h |    4 ++++
 2 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/environment.c b/environment.c
index e278bce..a3b6bab 100644
--- a/environment.c
+++ b/environment.c
@@ -7,6 +7,9 @@
  * even if you might want to know where the git directory etc
  * are.
  */
+#include <sys/time.h>
+#include <sys/resource.h>
+
 #include "cache.h"
 
 char git_default_email[MAX_GITNAME];
@@ -75,6 +78,13 @@ static void setup_git_env(void)
 	git_graft_file = getenv(GRAFT_ENVIRONMENT);
 	if (!git_graft_file)
 		git_graft_file = git_pathdup("info/grafts");
+	
+	if (DYNAMIC_WINDOW_SIZE) {
+		struct rlimit *as = malloc(sizeof(struct rlimit));
+		if ( (getrlimit(RLIMIT_AS, as) == 0) && ((int)(as->rlim_cur) > 0) ) 
+			packed_git_window_size = (unsigned int)(as->rlim_cur * DYNAMIC_WINDOW_SIZE_PERCENTAGE);
+		free(as);
+	}
 }
 
 int is_bare_repository(void)
diff --git a/git-compat-util.h b/git-compat-util.h
index e20b1e8..9603ca6 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -182,6 +182,8 @@ extern int git_munmap(void *start, size_t length);
 
 /* This value must be multiple of (pagesize * 2) */
 #define DEFAULT_PACKED_GIT_WINDOW_SIZE (1 * 1024 * 1024)
+#define DYNAMIC_WINDOW_SIZE 0
+#define DYNAMIC_WINDOW_SIZE_PERCENTAGE 0
 
 #else /* NO_MMAP */
 
@@ -192,6 +194,8 @@ extern int git_munmap(void *start, size_t length);
 	(sizeof(void*) >= 8 \
 		?  1 * 1024 * 1024 * 1024 \
 		: 32 * 1024 * 1024)
+#define DYNAMIC_WINDOW_SIZE 1
+#define DYNAMIC_WINDOW_SIZE_PERCENTAGE 0.85
 
 #endif /* NO_MMAP */
 
--