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authorBoris Kolpackov <boris@codesynthesis.com>2018-11-20 12:08:36 +0200
committerBoris Kolpackov <boris@codesynthesis.com>2018-11-20 12:10:41 +0200
commite4c4d8d65ea675eaa56c85661ba42e112ab70f4b (patch)
tree6f60d93f962bdf85ad92e8bb8bd49646cb62cab4 /build2
parentcf6374ec9a2fc3c765a07dcad73e05ea757ee477 (diff)
Improve workaround for backwards modification time issue
Diffstat (limited to 'build2')
-rw-r--r--build2/cc/link-rule.cxx18
-rw-r--r--build2/depdb.cxx51
-rw-r--r--build2/depdb.hxx2
3 files changed, 46 insertions, 25 deletions
diff --git a/build2/cc/link-rule.cxx b/build2/cc/link-rule.cxx
index c4fd82b..981358e 100644
--- a/build2/cc/link-rule.cxx
+++ b/build2/cc/link-rule.cxx
@@ -2071,12 +2071,12 @@ namespace build2
if (dd.writing () || dd.mtime > mt)
scratch = update = true;
-#define MTIME_SANITY_CHECK
-#ifdef MTIME_SANITY_CHECK
+#define BUILD2_MTIME_CHECK
+#ifdef BUILD2_MTIME_CHECK
timestamp dd_tt (system_clock::now ());
#endif
- timestamp dd_ct (dd.close ());
+ dd.close ();
// If nothing changed, then we are done.
//
@@ -2560,7 +2560,7 @@ namespace build2
rm.cancel ();
-#ifdef MTIME_SANITY_CHECK
+#ifdef BUILD2_MTIME_CHECK
{
timestamp tp_mt (file_mtime (tp));
timestamp dd_mt (file_mtime (dd.path));
@@ -2568,11 +2568,11 @@ namespace build2
if (dd_mt > tp_mt)
fail << "backwards modification times:\n"
- << dd_tt << " window start\n"
- << dd_ct << " close mtime\n"
- << dd_mt << " " << dd.path.string () << '\n'
- << tp_mt << " " << tp.string () << '\n'
- << tp_tt << " window end";
+ << dd_tt << " window start\n"
+ << dd.mtime << " close mtime\n"
+ << dd_mt << " " << dd.path.string () << '\n'
+ << tp_mt << " " << tp.string () << '\n'
+ << tp_tt << " window end";
}
#endif
diff --git a/build2/depdb.cxx b/build2/depdb.cxx
index 8abd5f2..f0b0d21 100644
--- a/build2/depdb.cxx
+++ b/build2/depdb.cxx
@@ -201,7 +201,7 @@ namespace build2
fs_.put ('\n');
}
- timestamp depdb::
+ void depdb::
close ()
{
// If we are at eof, then it means all lines are good, there is the "end
@@ -225,9 +225,7 @@ namespace build2
fs_.clear ();
fs_.exceptions (fstream::failbit | fstream::badbit);
fs_.seekp (0, fstream::cur); // Required to switch from read to write.
- fs_.put ('\0');
-
- state_ = state::write; // See below.
+ state_ = state::write; // Write end marker below.
}
}
else
@@ -238,8 +236,6 @@ namespace build2
change (false); // Don't flush.
}
- fs_.put ('\0'); // The "end marker".
-
// Truncating an fstream is actually a non-portable pain in the butt.
// What if we leave the junk after the "end marker"? These files are
// pretty small and chances are they will occupy the filesystem's block
@@ -247,25 +243,50 @@ namespace build2
// actually be faster not to truncate.
}
- fs_.close ();
-
// On some platforms (currently confirmed on Windows and FreeBSD, both
// running as VMs) one can sometimes end up with a modification time that
// is quite a bit after the call to close(). And this messes with our
- // arrangement that a valid depdb should be no older than the target it
- // is for.
+ // arrangement that a valid depdb should be no older than the target it is
+ // for.
//
// Note that this does not seem to be related to clock adjustments but
// rather feels like the modification time is set when the changes
- // actually hit some lower-level layer (e.g., OS or filesystem driver).
- // One workaround that appears to work is to query the mtime. This seems
- // to force that layer to commit to a timestamp.
+ // actually hit some lower-level layer (e.g., OS or filesystem
+ // driver). One workaround that appears to work is to query the
+ // mtime. This seems to force that layer to commit to a timestamp.
+ //
+ // Well, this seems to work on FreeBSD but on Windows we may still end up
+ // getting the old mtime if we ask for it too soon. For such cases we are
+ // going to just set it ourselves.
//
#if defined(_WIN32) || defined(__FreeBSD__)
+# define BUILD2_NEED_MTIME_FIX
+#endif
+
+#ifdef BUILD2_NEED_MTIME_FIX
+ timestamp mt;
+#endif
+
if (state_ == state::write)
- mtime = file_mtime (path);
+ {
+#ifdef BUILD2_NEED_MTIME_FIX
+ mt = system_clock::now ();
#endif
+ fs_.put ('\0'); // The "end marker".
+ }
+
+ fs_.close ();
+
+#ifdef BUILD2_NEED_MTIME_FIX
+ if (state_ == state::write)
+ {
+ // Save the original returned time for debugging.
+ //
+ mtime = file_mtime (path);
- return mtime;
+ if (mtime < mt)
+ file_mtime (path, mt);
+ }
+#endif
}
}
diff --git a/build2/depdb.hxx b/build2/depdb.hxx
index ffb3b89..7c9e464 100644
--- a/build2/depdb.hxx
+++ b/build2/depdb.hxx
@@ -90,7 +90,7 @@ namespace build2
// may be left in the old/currupt state. Note that in the read mode this
// function will "chop off" lines that haven't been read.
//
- timestamp
+ void
close ();
// Read the next line. If the result is not NULL, then it is a pointer to