[PATCH v2 3/6] git-compat-util: make MAX_IO_SIZE define globally available

From: Jeff King <peff@peff.net>
To: "René Scharfe" <l.s.r@web.de>
Cc: Junio C Hamano <gitster@pobox.com>,
	git@vger.kernel.org,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>
Subject: [PATCH v2 3/6] git-compat-util: make MAX_IO_SIZE define globally available
Date: Wed, 17 Aug 2022 02:06:58 -0400	[thread overview]
Message-ID: <YvyFggmzXAGf3jlL@coredump.intra.peff.net> (raw)
In-Reply-To: <YvyE1RDFVAg4uQo1@coredump.intra.peff.net>

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 <peff@peff.net>
---
I did actually write xwrite_nonblock() at first, and I could be
persuaded to go in that direction if we prefer. But given that using it
sanely requires the caller to have a poll() loop, I feel like
pipe_command() is already the right level of abstraction.

 git-compat-util.h | 22 ++++++++++++++++++++++
 wrapper.c         | 22 ----------------------
 2 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/git-compat-util.h b/git-compat-util.h
index 36a25ae252..6aee4d92e7 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -998,6 +998,28 @@ 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 <alloca.h>
 # define xalloca(size)      (alloca(size))
diff --git a/wrapper.c b/wrapper.c
index cfe79bd081..299d6489a6 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -161,28 +161,6 @@ void xsetenv(const char *name, const char *value, int overwrite)
 		die_errno(_("could not setenv '%s'"), name ? name : "(null)");
 }
 
-/*
- * 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
-
 /**
  * xopen() is the same as open(), but it die()s if the open() fails.
  */
-- 
2.37.2.881.gb57357660c

