Find alternative to SharpZipLib

[abeham]

We recently tried to do some updating of existing zip files using the sharpziplib that we include in the PluginInfrastructure. What should have been easy turned into a long bug hunting session with the result that this is simply broken for Zip64 stored zip files (the default), but does work with files stored using Zip32.

In this process we noted that the last commit to SharpZipLib was 2 years ago, the last release was more than 4 years ago. It looks like the project has been abandoned.

We should look for alternative Zip libraries that are actively maintained. We saw that in .NET 4.5 the System.IO.Compression namespace got new classes to handle Zip files (in .NET 4 and earlier only Gzip is supported). If this could be used in our project it would be a reason to switch to .NET 4.5 in my opinion.

TODO: * Check if there is a bug in UploadPluginsView.CreateZipPackage()

[ascheibe]

One other zip lib (that also supports zip64) that I know of is ​http://dotnetzip.codeplex.com/. But it also seems to be abandoned now, I looked at the changelog, last commit was in 2012.

[gkronber]

Discussion in architects meeting: ascheibe checks if projects with external partners are compatible

[ascheibe]

patch that switches persistence from SharpZipLib to IO.Compression

[ascheibe]

I measured the time it takes to save and load files with SharpZipLib and IO.Compression.ZipArchive:

Test 12 MB file

Type	Time (in sec, avg. of 3 repetitions
SharpZipLib - Load	7.32
SharpZipLib - Save	7.14
.Net ZipArchive - Load	7.12
.Net ZipArchive - Save	7.21

Test 88 MB file

Type	Time (in sec, avg. of 3 repetitions
SharpZipLib - Load	43.97
SharpZipLib - Save	43.80
.Net ZipArchive - Load	42.61
.Net ZipArchive - Save	43.03

File sizes:

File	Exact Size SharpZipLib	Exact Size .Net ZipArchive
12 MB	11.9 MB	12.5 MB
88 MB	86.5 MB	92.9 MB

[ascheibe]

r11650 switched persistence, instance providers, plugin infrastructure and MathJax to System.IO.Compression

[ascheibe]

r11651 removed SharpZipLib settings and files from the services and slave projects

[ascheibe]

While rewritting the code I found something which may be a bug: UploadPluginsView.CreateZipPackage() creates entries in a zip archive, but does not save anything to these entries. Is this ok or is this a bug?

[gkronber]

Replying to ascheibe:

While rewritting the code I found something which may be a bug: UploadPluginsView.CreateZipPackage() creates entries in a zip archive, but does not save anything to these entries. Is this ok or is this a bug?

This is indeed a bug. The functionality to upload plugins to the server has never been used. Generally the plugin-infrastructure contains a lot of code and complexity that should be removed because we stopped supporting plugin-updates.

[ascheibe]

Ok, thank you for the info, then we will clean this up in the future in a seperate ticket.

[abeham]

Changes look good. I tested

• I looked through the code changes
  • I noticed that in XmlGenerator.cs the compression level was changed from 5 to CompressionLevel.Optimal. This change should only affect the AlgorithmView and ProblemView for the OKB. I noticed that there is no intermediate compression level, it's either fastest or optimal (and none ofc).
• I quickly tested loading several problem instances, everything worked
• I tried to find remaining traces of 'sharpzip' or 'ziplib' in the working copy, none found

Good work, please release this after #2280.

[ascheibe]

r11932: merged r11650, r11651 into stable