index-pack: Disable threading on cygwin

The Cygwin implementation of pread() is not thread-safe since, just
like the emulation provided by compat/pread.c, it uses a sequence of
seek-read-seek calls. In order to avoid failues due to thread-safety
issues, commit b038a61 disables threading when NO_PREAD is defined.
(ie when using the emulation code in compat/pread.c).

We introduce a new build variable, NO_THREAD_SAFE_PREAD, which allows
use to disable the threaded index-pack code on cygwin, in addition to
the above NO_PREAD case.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Makefile b/Makefile
index 4592f1f2ee82a656c9dfd2fcf9132e4fd132bc67..67d761e83adad8e3332b22fbe753e0cdb81b1a83 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -158,6 +158,9 @@ all::
 # Define NO_PREAD if you have a problem with pread() system call (e.g.
 # cygwin1.dll before v1.5.22).
 #
+# Define NO_THREAD_SAFE_PREAD if your pread() implementation is not
+# thread-safe. (e.g. compat/pread.c or cygwin)
+#
 # Define NO_FAST_WORKING_DIRECTORY if accessing objects in pack files is
 # generally faster on your platform than accessing the working directory.
 #
@@ -1051,6 +1054,7 @@ ifeq ($(uname_O),Cygwin)
                NO_IPV6 = YesPlease
                OLD_ICONV = UnfortunatelyYes
        endif
+       NO_THREAD_SAFE_PREAD = YesPlease
        NEEDS_LIBICONV = YesPlease
        NO_FAST_WORKING_DIRECTORY = UnfortunatelyYes
        NO_TRUSTABLE_FILEMODE = UnfortunatelyYes
@@ -1659,6 +1663,10 @@ endif
 ifdef NO_PREAD
        COMPAT_CFLAGS += -DNO_PREAD
        COMPAT_OBJS += compat/pread.o
+       NO_THREAD_SAFE_PREAD = YesPlease
+endif
+ifdef NO_THREAD_SAFE_PREAD
+       BASIC_CFLAGS += -DNO_THREAD_SAFE_PREAD
 endif
 ifdef NO_FAST_WORKING_DIRECTORY
        BASIC_CFLAGS += -DNO_FAST_WORKING_DIRECTORY

diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index dc2cfe6e6f63b6628f8a358f2f3b3e65c14e3b8d..470547835ca41888817b85dc4b7ed39273ede784 100644 (file)
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -39,8 +39,8 @@ struct base_data {
        int ofs_first, ofs_last;
 };
 
-#if !defined(NO_PTHREADS) && defined(NO_PREAD)
-/* NO_PREAD uses compat/pread.c, which is not thread-safe. Disable threading. */
+#if !defined(NO_PTHREADS) && defined(NO_THREAD_SAFE_PREAD)
+/* pread() emulation is not thread-safe. Disable threading. */
 #define NO_PTHREADS
 #endif