When blocks terminate (either COMPLETE or CORRUPT/DEAD/BADSEGNUM), the
_shares_from_server dict was being popped incorrectly (using shnum as the
index instead of serverid). I'm still thinking through the consequences of
this bug. It was probably benign and really hard to detect. I think it would
cause us to incorrectly believe that we're pulling too many shares from a
server, and thus prefer a different server rather than asking for a second
share from the first server. The diversity code is intended to spread out the
number of shares simultaneously being requested from each server, but with
this bug, it might be spreading out the total number of shares requested at
all, not just simultaneously. (note that SegmentFetcher is scoped to a single
segment, so the effect doesn't last very long).
No behavioral changes, just updating variable/method names and log messages.
The effects outside these three files should be minimal: some exception
messages changed (to say "server" instead of "peer"), and some internal class
names were changed. A few things still use "peer" to minimize external
changes, like UploadResults.timings["peer_selection"] and
happinessutil.merge_peers, which can be changed later.
Pass around IServer instance instead of (peerid, rref) tuple. Replace
"descriptor" with "server". Other replacements:
get_all_servers -> get_connected_servers/get_known_servers
get_servers_for_index -> get_servers_for_psi (now returns IServers)
This change still needs to be pushed further down: lots of code is now
getting the IServer and then distributing (peerid, rref) internally.
Instead, it ought to distribute the IServer internally and delay
extracting a serverid or rref until the last moment.
no_network.py was updated to retain parallelism.
* repairer (really the uploader) reads beyond end of input file (Uploadable)
* new-downloader does not tolerate overreads
* uploader does lots of tiny reads (inefficient)
This fixes the last two. The uploader still does a single overread at the end
of the input file, but now that's ok so we can leave it in place. The
uploader now expects the Uploadable to behave like a normal disk
file (reading beyond EOF will return less data than was asked for), and now
the new-downloadable behaves that way.
fixes#1191
Patch by Brian. This patch description was actually written by Zooko, but I forged Brian's name on the "author" field so that he would get credit for this patch in revision control history.
deliver all shares at once instead of feeding them out one-at-a-time.
Also fix distribution of real-number-of-segments information: now all
CommonShares (not just the ones used for the first segment) get a
correctly-sized hashtree. Previously, the late ones might not, which would
make them crash and get dropped (causing the download to fail if the initial
set were insufficient, perhaps because one of their servers went away).
Update tests, add some TODO notes, improve variable names and comments.
Improve logging: add logparents, set more appropriate levels.
This avoids spamming the "recent uploads and downloads" /status page from
FileNode instances that were created for a directory read but which nobody is
ever going to read from. I also cleaned up the way DownloadStatus instances
are made to only ever do it in the CiphertextFileNode, not in the
higher-level plaintext FileNode. Also fixed DownloadStatus handling of read
size, thanks to David-Sarah for the catch.
seems to avoid the #1155 log message which reveals the URI (and filecap).
Also add an [ERROR] marker to the flog entry, since unregisterProducer also
makes interrupted downloads appear "200 OK"; this makes it more obvious that
the download did not complete.
The lost-progress bug occurred when two simultanous read() calls fetched
different segments, and the first one failed (due to corruption, or the other
bugs in #1154): the second read() would never complete. While in this state,
cancelling the second read by having its consumer call stopProducing) would
trigger the cancel-intolerance bug. Finally, in downloader.node.Cancel,
prevent late cancels by adding an 'active' flag
The Range header causes n.read() to be called with an offset= of type 'long',
which eventually got used in a Spans/DataSpans object's __len__ method.
Apparently python doesn't permit __len__() to return longs, only ints.
Rewrote Spans/DataSpans to use s.len() instead of len(s) aka s.__len__() .
Added a test in test_download. Note that test_web didn't catch this because
it uses mock FileNodes for speed: it's probably time to rewrite that.
There is still an unresolved error-recovery problem in #1154, so I'm not
closing the ticket quite yet.
The fixed 10-second timer will eventually be replaced with a per-server
value, calculated based on observed response times.
test_hung_server.py: enhance to exercise DYHB=OVERDUE state. Split existing
mutable+immutable tests into two pieces for clarity. Reenabled several tests.
Deleted the now-obsolete "test_failover_during_stage_4".
- Make some important utility functions clearer and more thoroughly
documented.
- Assert in upload.servers_of_happiness that the buckets attributes
of PeerTrackers passed to it are mutually disjoint.
- Get rid of some silly non-Pythonisms that I didn't see when I first
wrote these patches.
- Make sure that should_add_server returns true when queried about a
shnum that it doesn't know about yet.
- Change Tahoe2PeerSelector.preexisting_shares to map a shareid to a set
of peerids, alter dependencies to deal with that.
- Remove upload.should_add_servers, because it is no longer necessary
- Move upload.shares_of_happiness and upload.shares_by_server to a utility
file.
- Change some points in Tahoe2PeerSelector.
- Compute servers_of_happiness using a bipartite matching algorithm that
we know is optimal instead of an ad-hoc greedy algorithm that isn't.
- Change servers_of_happiness to just take a sharemap as an argument,
change its callers to merge existing_shares and used_peers before
calling it.
- Change an error message in the encoder to be more appropriate for
servers of happiness.
- Clarify the wording of an error message in immutable/upload.py
- Refactor a happiness failure message to happinessutil.py, and make
immutable/upload.py and immutable/encode.py use it.
- Move the word "only" as far to the right as possible in failure
messages.
- Use a better definition of progress during peer selection.
- Do read-only peer share detection queries in parallel, not sequentially.
- Clean up logging semantics; print the query statistics whenever an
upload is unsuccessful, not just in one case.
When I first implemented #778, I just altered the error messages to refer to
servers where they referred to shares. The resulting error messages weren't
very good. These are a bit better.
The Tahoe2PeerSelector returned either NoSharesError or NotEnoughSharesError
for a variety of error conditions that weren't informatively described by them.
This patch creates a new error, UploadHappinessError, replaces uses of
NoSharesError and NotEnoughSharesError with it, and alters the error message
raised with the errors to be more in line with the new servers_of_happiness
behavior. See ticket #834 for more information.
