From: oetiker Date: Fri, 5 Dec 2008 15:18:11 +0000 (+0000) Subject: check for broken implementations of msync / MS_ASYNC where X-Git-Url: https://git.octo.it/?p=rrdtool.git;a=commitdiff_plain;h=dc2409c0e92ace2dfdf73c0c5d7f57baf48b490b check for broken implementations of msync / MS_ASYNC where the mtime does not get updated. warn and explicitly call utime in rrd_open when a file is opened rw. git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk/program@1696 a5681a0c-68f1-0310-ab6d-d61299d08faa --- diff --git a/acinclude.m4 b/acinclude.m4 index 38ee0c2..5ea34f0 100644 --- a/acinclude.m4 +++ b/acinclude.m4 @@ -506,43 +506,87 @@ esac AC_MSG_RESULT([${T_MD}$1${T_ME}]) ]) +dnl check + +AC_DEFUN([CHECK_FOR_WORKING_MS_ASYNC], [ +AC_MSG_CHECKING([if msync with MS_ASYNC updates the files mtime]) +AC_CACHE_VAL([rd_cv_ms_async], +[AC_RUN_IFELSE([AC_LANG_SOURCE([[ +#include +#include +#include +#include +#include +#include +#include +#include +int main(void){ + int fd; + struct stat stbuf; + char *addr; + int res; + char temp[] = "mmaptestXXXXXX"; + struct utimbuf newtime; + + time_t create_ts; + fd = mkstemp(temp); + if (fd == -1){ + perror(temp); + return 1; + } + write(fd,"12345\n", 6); + stat(temp, &stbuf); + create_ts = stbuf.st_mtime; + newtime.actime = 0; + newtime.modtime = 0; + utime(temp,&newtime); + addr = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); + if (addr == MAP_FAILED) { + perror("mmap"); + goto bad_exit; + } + addr[0]='x'; + res = msync(addr, 4, MS_ASYNC); + if (res == -1) { + perror("msync"); + goto bad_exit; + } + res = close(fd); + if (res == -1) { + perror("close"); + goto bad_exit; + } + /* The ASYNC means that we schedule the msync and return immediately. + Since we want to see if the modification time is updated upon + msync(), we have to make sure that our asynchronous request + completes before we stat below. In a real application, the + request would be completed at a random time in the future + but for this test we do not want to wait an arbitrary amount of + time, so force a commit now. */ + sync(); + stat(temp, &stbuf); + if (create_ts > stbuf.st_mtime){ + goto bad_exit; + } + unlink(temp); + return 0; + bad_exit: + unlink(temp); + return 1; +} +]])],[rd_cv_ms_async=ok],[rd_cv_ms_async=broken],[:])]) + + +if test "${rd_cv_ms_async}" = "ok"; then + AC_MSG_RESULT(yes) +else + AC_DEFINE_UNQUOTED(HAVE_BROKEN_MS_ASYNC, 1 , [set to 1 if msync with MS_ASYNC fails to update mtime]) + AC_MSG_RESULT(no) + AC_MSG_WARN([With mmap access, your platform fails to update the files]) + AC_MSG_WARN([mtime. RRDtool will work around this problem by calling utime on each]) + AC_MSG_WARN([file it opens for rw access.]) + sleep 2 +fi -dnl --------------------------------------------------------------------------- -dnl CF_DISABLE_ECHO version: 10 updated: 2003/04/17 22:27:11 -dnl --------------- -dnl stolen from xterm aclocal.m4 -dnl -dnl You can always use "make -n" to see the actual options, but it's hard to -dnl pick out/analyze warning messages when the compile-line is long. -dnl -dnl Sets: -dnl ECHO_LT - symbol to control if libtool is verbose -dnl ECHO_LD - symbol to prefix "cc -o" lines -dnl RULE_CC - symbol to put before implicit "cc -c" lines (e.g., .c.o) -dnl SHOW_CC - symbol to put before explicit "cc -c" lines -dnl ECHO_CC - symbol to put before any "cc" line -dnl -AC_DEFUN([CF_DISABLE_ECHO],[ -AC_MSG_CHECKING(if you want to see long compiling messages) -CF_ARG_DISABLE(echo, - [ --disable-echo display "compiling" commands], - [ - ECHO_LT='--silent' - ECHO_LD='@echo linking [$]@;' - RULE_CC=' @echo compiling [$]<' - SHOW_CC=' @echo compiling [$]@' - ECHO_CC='@' -],[ - ECHO_LT='' - ECHO_LD='' - RULE_CC='# compiling' - SHOW_CC='# compiling' - ECHO_CC='' ]) -AC_MSG_RESULT($enableval) -AC_SUBST(ECHO_LT) -AC_SUBST(ECHO_LD) -AC_SUBST(RULE_CC) -AC_SUBST(SHOW_CC) -AC_SUBST(ECHO_CC) -])dnl + diff --git a/configure.ac b/configure.ac index b3d5c80..0d39a7b 100644 --- a/configure.ac +++ b/configure.ac @@ -366,6 +366,8 @@ AC_FULL_IEEE CONFIGURE_PART(Resolve Portability Issues) +CHECK_FOR_WORKING_MS_ASYNC + dnl Do we need getopt_long build_getopt=no diff --git a/src/rrd_open.c b/src/rrd_open.c index 5598546..5a908da 100644 --- a/src/rrd_open.c +++ b/src/rrd_open.c @@ -9,6 +9,7 @@ #include #include #include +#include #include "rrd_tool.h" #include "unused.h" @@ -173,10 +174,6 @@ rrd_file_t *rrd_open( } else { if (rdwr & RRD_READWRITE) { flags |= O_RDWR; -#ifdef HAVE_MMAP - rrd_simple_file->mm_flags = MAP_SHARED; - rrd_simple_file->mm_prot |= PROT_WRITE; -#endif } if (rdwr & RRD_CREAT) { flags |= (O_CREAT | O_TRUNC); @@ -199,6 +196,21 @@ rrd_file_t *rrd_open( goto out_free; } +#ifdef HAVE_MMAP +#ifdef HAVE_BROKEN_MS_ASYNC + if (rdwr & RRD_READWRITE) { + /* some unices, the files mtime does not get update + on msync MS_ASYNC, in order to help them, + we update the the timestamp at this point. + The thing happens pretty 'close' to the open + call so the chances of a race should be minimal. + + Maybe ask your vendor to fix your OS ... */ + utime(file_name,NULL); + } +#endif +#endif + /* Better try to avoid seeks as much as possible. stat may be heavy but * many concurrent seeks are even worse. */ if (newfile_size == 0 && ((fstat(rrd_simple_file->fd, &statb)) < 0)) { @@ -360,6 +372,7 @@ rrd_file_t *rrd_open( if (data != MAP_FAILED) munmap(data, rrd_file->file_len); #endif + close(rrd_simple_file->fd); out_free: free(rrd_file->pvt);