From: Junio C Hamano <gitster@xxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxx>
---
Hi Junio,
I made some small changes to your patch:
- renamed FAKE_PREAD_NOT_THREAD_SAFE to NO_THREAD_SAFE_PREAD
- when NO_PREAD, set NO_THREAD_SAFE_PREAD in the Makefile, rather
than in git-compat-util.h
- set NO_THREAD_SAFE_PREAD in the non-conditional part of the
cygwin config section (ie not just versions before 1.7.x)
I can only test this by using it (all relevant tests pass with or without
this patch, after all), so I have installed it for day-to-day use. I don't
anticipate any problems, but I guess this patch has not actually been
tested yet ... :-D
HTH
ATB,
Ramsay Jones
Makefile | 8 ++++++++
builtin/index-pack.c | 4 ++--
2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/Makefile b/Makefile
index 4592f1f..67d761e 100644
--- 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 dc2cfe6..4705478 100644
--- 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
--
1.7.11.1.gef8c760
--
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