* tl/relax-in-poll-emulation: compat/poll: sleep 1 millisecond to avoid busy wait
Read-only operations such as "git status" that internally refreshes the index write out the refreshed index to the disk to optimize future accesses to the working tree, but this could race with a "read-write" operation that modify the index while it is running. Detect such a race and avoid overwriting the index. Duy raised a good point that we may need to do the same for the normal writeout codepath, not just the "opportunistic" update codepath. While that is true, nobody sane would be running two simultaneous operations that are clearly write-oriented competing with each other against the same index file. So in that sense that can be done as a less urgent follow-up for this topic. * ym/fix-opportunistic-index-update-race: read-cache.c: verify index file before we opportunistically update it wrapper.c: add xpread() similar to xread()
Instead of running N pair-wise diff-trees when inspecting a N-parent merge, find the set of paths that were touched by walking N+1 trees in parallel. These set of paths can then be turned into N pair-wise diff-tree results to be processed through rename detections and such. And N=2 case nicely degenerates to the usual 2-way diff-tree, which is very nice. * ks/tree-diff-nway: mingw: activate alloca combine-diff: speed it up, by using multiparent diff tree-walker directly tree-diff: rework diff_tree() to generate diffs for multiparent cases as well Portable alloca for Git tree-diff: reuse base str(buf) memory on sub-tree recursion tree-diff: no need to call "full" diff_tree_sha1 from show_path() tree-diff: rework diff_tree interface to be sha1 based tree-diff: diff_tree() should now be static tree-diff: remove special-case diff-emitting code for empty-tree cases tree-diff: simplify tree_entry_pathcmp tree-diff: show_path prototype is not needed anymore tree-diff: rename compare_tree_entry -> tree_entry_pathcmp tree-diff: move all action-taking code out of compare_tree_entry() tree-diff: don't assume compare_tree_entry() returns -1,0,1 tree-diff: consolidate code for emitting diffs and recursion in one place tree-diff: show_tree() is not needed tree-diff: no need to pass match to skip_uninteresting() tree-diff: no need to manually verify that there is no mode change for a path combine-diff: move changed-paths scanning logic into its own function combine-diff: move show_log_first logic/action out of paths scanning
SwitchToThread() only gives away the rest of the current time slice to another thread in the current process. So if the thread that feeds the file decscriptor we're polling is not in the current process, we get busy-waiting. I played around with this quite a bit. After trying some more complex schemes, I found that what worked best is to just sleep 1 millisecond between iterations. Though it's a very short time, it still completely eliminates the busy wait condition, without hurting perf. There code uses SleepEx(1, TRUE) to sleep. See this page for a good discussion of why that is better than calling SwitchToThread, which is what was used previously: http://stackoverflow.com/questions/1383943/switchtothread-vs-sleep1 Note that calling SleepEx(0, TRUE) does *not* solve the busy wait. The most striking case was when testing on a UNC share with a large repo, on a single CPU machine. Without the fix, it took 4 minutes 15 seconds, and with the fix it took just 1:08! I think it's because git-upload-pack's busy wait was eating the CPU away from the git process that's doing the real work. With multi-proc, the timing is not much different, but tons of CPU time is still wasted, which can be a killer on a server that needs to do bunch of other things. I also tested the very fast local case, and didn't see any measurable difference. On a big repo with 4500 files, the upload-pack took about 2 seconds with and without the fix. [jc: this was first accepted in msysgit tree in May 2012 via a pull request and Paolo Bonzini has also accepted the same fix to Gnulib around the same time; see $gmane/247518 for a bit more detail] Signed-off-by: Stepan Kasal <kasal@ucw.cz> Acked-by: Johannes Sixt <j6t@kdbg.org> Acked-by: Erik Faye-Lund <kusmabite@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
It is a common mistake to call read(2)/pread(2) and forget to anticipate that they may return error with EAGAIN/EINTR when the system call is interrupted. We have xread() helper to relieve callers of read(2) from having to worry about it; add xpread() helper to do the same for pread(2). Update the caller in the builtin/index-pack.c and the mmap emulation in compat/. Signed-off-by: Yiannis Marangos <yiannis.marangos@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* jk/commit-dates-parsing-fix: t4212: loosen far-in-future test for AIX date: recognize bogus FreeBSD gmtime output
Both MSVC and MINGW have alloca(3) definitions in malloc.h, so by moving win32-compat alloca.h from compat/vcbuild/include/ to compat/win32/ , which is included by both MSVC and MINGW CFLAGS, we can make alloca() work on both those Windows environments. In MINGW, malloc.h has explicit check for GNUC and if it is so, defines alloca to __builtin_alloca, so it looks like we don't need to add any code to here-shipped alloca.h to get optimum performance. Compile-tested on Windows in MSysGit. Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru> Acked-by: Erik Faye-Lund <kusmabite@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Finishing touches for portability. * jk/commit-dates-parsing-fix: t4212: loosen far-in-future test for AIX date: recognize bogus FreeBSD gmtime output
Most gmtime implementations return a NULL value when they encounter an error (and this behavior is specified by ANSI C and POSIX). FreeBSD's implementation, however, will simply leave the "struct tm" untouched. Let's also recognize this and convert it to a NULL (with this patch, t4212 should pass on FreeBSD). Reported-by: René Scharfe <l.s.r@web.de> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* mr/msvc-link-with-lcurl: MSVC: allow linking with the cURL library