hgwebdir: allow a repository to be hosted at "/" This can be useful in general, but will also be useful for hosting subrepos, with the main repo at /.

httppeer: eliminate decompressresponse() proxy Now that the response instance itself is wrapped with error handling, we no longer need this code. This code became dead with the previous patch because the added code catches HTTPException and re-raises as something else.

httppeer: wrap HTTPResponse.read() globally There were a handful of places in the code where HTTPResponse.read() was called with no explicit error handling or with inconsistent error handling. In order to eliminate this class of bug, we globally swap out HTTPResponse.read() with a unified error handler. I initially attempted to fix all call sites. However, after going down that rabbit hole, I figured it was best to just change read() to do what we want. This appears to be a worthwhile change, as the tests demonstrate many of our uncaught exceptions go away. To better represent this class of failure, we introduce a new error type. The main benefit over IOError is it can hold a hint. I'm receptive to tweaking its name or inheritance.

tests: add tests for poorly behaving HTTP server I've spent several hours over the past few weeks investigating networking failures involving hg.mozilla.org. As part of this, it has become clear that the Mercurial client's error handling when it encounters network failures is far from robust. To prove this is true, I've devised a battery of tests simulating various network failures, notably premature connection closes. To achieve this, I've implemented an extension that monkeypatches the built-in HTTP server and hooks in at the socket level and allows various events to occur based on config options. For example, you can refuse to accept() a client socket or you can close() the socket after N bytes have been sent or received. The latter effectively simulates an unexpected connection drop (and these occur all the time in the real world). The new test file launches servers exhibiting various "bad" behaviors and points a client at them. As the many TODO comments in the test call attention to, Mercurial often displays unhelpful errors when network-related failures occur. This makes it difficult for users to understand what's going on and difficult for server administrators to pinpoint root causes without packet tracing. Upcoming patches will attempt to fix these error handling deficiencies.

phases: emit phases to pushkey protocol in deterministic order An upcoming test will report exact bytes sent over the wire protocol. Without this change, the ordering of phases listkey data is non-deterministic.

keepalive: send HTTP request headers in a deterministic order An upcoming patch will add low-level testing of the bytes being sent over the wire. As part of developing that test, I discovered that the order of headers in HTTP requests wasn't deterministic. This patch makes the order deterministic to make things easier to test.

revset: properly parse "descend" argument of followlines() We parse "descend" symbol as a Boolean using getboolean (prior extraction by getargsdict already checked that it is a symbol). In tests, check for error cases and vary Boolean values here and there.

revsetlang: add a getboolean helper function This will be used to parse followlines's "descend" argument.

track-tags: write all tag changes to a file The tag changes information we compute is now written to disk. This gives hooks full access to that data. The format picked for that file uses a 2 characters prefix for the action: -R: tag removed +A: tag added -M: tag moved (old value) +M: tag moved (new value) This format allows hooks to easily select the line that matters to them without having to post process the file too much. Here is a couple of examples: * to select all newly tagged changeset, match "^+", * to detect tag move, match "^.M", * to detect tag deletion, match "-R". Once again we rely on the fact the tag tests run through all possible situations to test this change.

track-tags: compute the actual differences between tags pre/post transaction We now compute the proper actuall differences between tags before and after the transaction. This catch a couple of false positives in the tests. The compute the full difference since we are about to make this data available to hooks in the next changeset.

track-tags: introduce first bits of tags tracking during transaction This changeset introduces detection of tags changes during transaction. When this happens a 'tag_moved=1' argument is set for hooks, similar to what we do for bookmarks and phases. This code is disabled by default as there are still various performance concerns. Some require a smarter use of our existing tag caches and some other require rework around the transaction logic to skip execution when unneeded. These performance improvements have been delayed, I would like to be able to experiment and stabilize the feature behavior first. Later changesets will push the concept further and provide a way for hooks to know what are the actual changes introduced by the transaction. Similar work is needed for the other families of changes (bookmark, phase, obsolescence, etc). Upgrade of the transaction logic will likely be performed at the same time. The current code can report some false positive when .hgtags file changes but resulting tags are unchanged. This will be fixed in the next changeset. For testing, we simply globally enable a hook in the tag test as all the possible tag update cases should exist there. A couple of them show the false positive mentioned above. See in code documentation for more details.

tags: introduce a function to return a valid fnodes list from revs This will get used to compare tags between two set of revisions during a transaction (pre and post heads). The end goal is to be able to track tags movement in transaction hooks.

context: possibly yield initial fctx in blockdescendants() If initial 'fctx' has changes in line range with respect to its parents, we yield it first. This makes 'followlines(..., descend=True)' consistent with 'descendants()' revset which yields the starting revision. We reuse one iteration of blockancestors() which does exactly what we want. In test-annotate.t, adjust 'startrev' in one case to cover the situation where the starting revision does not touch specified line range.

context: add an assertion checking linerange consistency in blockdescendants() If this assertion fails, this indicates a flaw in the algorithm. So fail fast instead of possibly producing wrong results. Also extend the target line range in test to catch a merge changeset with all its parents.