From ec4f39b2333db94096ec2d6b900eabaf4d1e3f1b Mon Sep 17 00:00:00 2001 From: Jeff King Date: Wed, 17 Aug 2022 02:06:58 -0400 Subject: git-compat-util: make MAX_IO_SIZE define globally available We define MAX_IO_SIZE within wrapper.c, but it's useful for any code that wants to do a raw write() for whatever reason (say, because they want different EAGAIN handling). Let's make it available everywhere. The alternative would be adding xwrite_foo() variants to give callers more options. But there's really no reason MAX_IO_SIZE needs to be abstracted away, so this give callers the most flexibility. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- git-compat-util.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'git-compat-util.h') diff --git a/git-compat-util.h b/git-compat-util.h index 58d7708296..79977caed6 100644 --- a/git-compat-util.h +++ b/git-compat-util.h @@ -995,6 +995,28 @@ static inline unsigned long cast_size_t_to_ulong(size_t a) return (unsigned long)a; } +/* + * Limit size of IO chunks, because huge chunks only cause pain. OS X + * 64-bit is buggy, returning EINVAL if len >= INT_MAX; and even in + * the absence of bugs, large chunks can result in bad latencies when + * you decide to kill the process. + * + * We pick 8 MiB as our default, but if the platform defines SSIZE_MAX + * that is smaller than that, clip it to SSIZE_MAX, as a call to + * read(2) or write(2) larger than that is allowed to fail. As the last + * resort, we allow a port to pass via CFLAGS e.g. "-DMAX_IO_SIZE=value" + * to override this, if the definition of SSIZE_MAX given by the platform + * is broken. + */ +#ifndef MAX_IO_SIZE +# define MAX_IO_SIZE_DEFAULT (8*1024*1024) +# if defined(SSIZE_MAX) && (SSIZE_MAX < MAX_IO_SIZE_DEFAULT) +# define MAX_IO_SIZE SSIZE_MAX +# else +# define MAX_IO_SIZE MAX_IO_SIZE_DEFAULT +# endif +#endif + #ifdef HAVE_ALLOCA_H # include # define xalloca(size) (alloca(size)) -- cgit v1.2.3