Merge lp:~gz/bzr/installer_plugin_script_timestamp_rounding into lp:bzr

[Martin Packman]

Make windows installer use a 2 second resolution for plugin script timestamps to avoid recompilation at runtime

See bug 600803 for the background. The aim is to avoid a potential problem when installing onto a FAT filesystem.

By rounding the timestamps of the plugin script files prior to byte compilation, can ensure that the py mtime and pyo internal timestamp match, even with a 2 second resolution installation drive. Without this change bzr.exe may semi-randomly recompile some pyo files from source at runtime.

Nevertheless, this is a daft hack for a weird edge case, so might not be worth merging.

Ideally all this py2exe stuff would live in bzr-windows-installers where sane people don't have to look at it, but some poor fool has to volunteer to do that still I guess.

[John A Meinel (jameinel)]

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Martin [gz] wrote:
> Martin [gz] has proposed merging lp:~gz/bzr/installer_plugin_script_timestamp_rounding into lp:bzr.
>
> Requested reviews:
> bzr-core (bzr-core)
>
>
> See bug 600803 for the background. The aim is to avoid a potential problem when installing onto a FAT filesystem.
>
> By rounding the timestamps of the plugin script files prior to byte compilation, can ensure that the py mtime and pyo internal timestamp match, even with a 2 second resolution installation drive. Without this change bzr.exe may semi-randomly recompile some pyo files from source at runtime.
>
> Nevertheless, this is a daft hack for a weird edge case, so might not be worth merging.
>
> Ideally all this py2exe stuff would live in bzr-windows-installers where sane people don't have to look at it, but some poor fool has to volunteer to do that still I guess.
>

Are we sure we round the same way ISS does? Would it be better to just
disable the rounding check?

John
=:->

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[Martin Packman (gz)]

It doesn't currently matter as lp:~gz/bzr-windows-installers/use_utc_timestamps_600803 now also prevents Inno from doing any rounding. Just that change covers the far more common case of installing onto NTFS, this is just icing for FAT. It may be possible to let Inno continue to round, but apart from then being able to notice problems with this code even on NTFS I see absolutely no benefit in having the installer mess with timestamps.

[Robert Collins (lifeless)]

This is fine with me - lets land it.

review: Approve

[lp:~gz/bzr/installer_plugin_script_timestamp_rounding]

5333. By Martin Packman on 2010-07-04

Use same timestamp rounding logic as Inno, just in case

[Martin Packman (gz)]

For the curious, the Inno logic in Compile.pas goes like:
    Dec64(Integer64(FL.TimeStamp), Mod64(Integer64(FL.TimeStamp), TimeStampRounding * 10000000));
Where FL.TimeStamp is FILETIME derived 100-nanosecond counter, and 'Dec' stands for decrement.

I've updated this branch to do the same, so it would be safe not to use TimeStampRounding=0 and leave the default of 2.

[Martin Packman (gz)]

sent to pqm by email

=== modified file 'setup.py'
--- setup.py	2010-06-22 04:15:25 +0000
+++ setup.py	2010-07-04 07:09:27 +0000
@@ -538,6 +538,14 @@
             #                time before living with docstring stripping
             optimize = 1
             compile_names = [f for f in self.outfiles if f.endswith('.py')]
+            # Round mtime to nearest even second so that installing on a FAT
+            # filesystem bytecode internal and script timestamps will match
+            for f in compile_names:
+                mtime = os.stat(f).st_mtime
+                remainder = mtime % 2
+                if remainder:
+                    mtime -= remainder
+                    os.utime(f, (mtime, mtime))
             byte_compile(compile_names,
                          optimize=optimize,
                          force=self.force, prefix=self.install_dir,