Using pkg_resources is probably better if it works -- zope.interface doesn't have a __version__ attribute that we can query, but pkg_resources knows zope.interface's version number, for one thing.
This code falls back to the old way -- looking at the __version__ attributes and __file__ attributes -- if the pkg_resources way doesn't answer.
Note that this patch also changes the capitalization of "Nevow", "Twisted", and "pyOpenSSL", and the spelling of "allmydata-tahoe". These changes are not frivolous: they are reflecting the fact that we are naming Python packages (technically called Python "distributions") instead of Python modules (technically and confusingly called Python "packages") here. The package ("distribution") is named "allmydata-tahoe". The module ("package") is named "allmydata".
When this feature is turned on, then setuptools doesn't create easy-install.pth, setuptools.pth, or site.py in the target site-packages dir. I don't know why not and we should probably open a ticket on the setuptools tracker and/or hack setuptools to create those files anyway. But for now (for the Tahoe-1.3.0 release), we're going to leave --multi-version mode off and require users to manually uninstall any packages which are too old and thus conflict with our newer dependencies.
Because Brian argues that the file contains a description of the wui as well as of the wapi, and because the name "webapi.txt" might be more obvious to the untrained eye.
This is necessary, because if setuptools looks at the directory listing, then it follows the link named "More Info" in attempt to download the file, and this fails.
This implements an immutable repairer by marrying a CiphertextDownloader to a CHKUploader. It extends the IDownloadTarget interface so that the downloader can provide some metadata that the uploader requires.
The processing is incremental -- it uploads the first segments before it finishes downloading the whole file. This is necessary so that you can repair large files without running out of RAM or using a temporary file on the repairer.
It requires only a verifycap, not a readcap. That is: it doesn't need or use the decryption key, only the integrity check codes.
There are several tests marked TODO and several instances of XXX in the source code. I intend to open tickets to document further improvements to functionality and testing, but the current version is probably good enough for Tahoe-1.3.0.
It used to be a map from shnum to a string saying "placed this share on XYZ server". The new definition is more in keeping with the "sharemap" object that results from immutable file checking and repair, and it is more useful to the repairer, which is a consumer of immutable upload results.
