On linux, write tests are failing because data written to fuse isn't showing
up in tahoe by the time it's checked. it's not clear where this is originating,
since the fuse implementation [should be] waiting for completion of tahoe
operations before returning from its calls. This adds an option to control the
duration of a pause between the fuse write and the check of tahoe, which is by
default set to 2s on linux, which - somewhat inexplicably - seems to 'fix' the
problem, in as far as it allows tests to complete.
previously, upon opening a file for reading, the open() call would block
while the entire file was retrieved from tahoe into the cache directory.
This change adds a DownloaderWithReadQueue class, and associated plumbing,
such that an open() will return promptly with the download initiated 'in
the background'. Subsequent read() operations will block until enough
data has been downloaded to satisfy that request. This provides a behaviour
similar to streaming, i.e. the client application will be able to read
data from the fuse interface while the remainder of the file is still being
downloaded.
this test uploads a test file to tahoe, and then reads the file from fuse,
but reads the blocks of the file in a random order; this is designed to
exercise the asynchronous download feature of blackmatch - where the file
is downloaded from tahoe asynchronously, and rather than blocking open()
for the entirety of the download, instead individual read() calls are
blocked until enough of the file has been downloaded to satisfy them
the code had a 'fullcleanup' flag internally which controlled whether
working directories were cleaned up. this promotes that to a command
line option (negated) '--no-cleanup' defaulting to False, i.e. do cleanup
this avoids dumping the repr of 1Mb of random data to stdout in the event
of a test failure, but rather just dumps the start/end of the errant strings
if the amount of data is > 200 chars repr'd
the repr_flags debug/logging function had a list of fields from the os
module that might be passed into an open() call, but it included at
least one which was available on the mac but not on linux. symmetrically
linux has numerous flags which are not present on the mac. the repr_flags
function is now tolerant of flags not being present, and has an expanded
list of flags
since the current tests assume that the implementation responds to changes made
to tahoe after mount, and impl_b prefetches and cached directory data, impl_b
fails the current 'read' test suite.
rather than reflect that problem in the overall failure of the runtests exit
code, this adds a 'todo' flag to the implementations table, and sets the todo
flag for impl_b. Thus errors will therein be reported in output, but not cause
a failing exit code.
