The problem with dumping all of the json response into the Request object at
once is that doing so starts the timeout for the next request to be received:
so if it takes longer than 60s to stream back the response to the client, the
client never gets it.
The correct solution is to use a Producer; then the timeout is only started
once all of the content is sent over the TCP connection.
This commit moves a bunch of the logic for deciding when to log the receipt and
completion of HTTP requests into SynapseRequest, rather than in the request
handling wrappers.
Advantages of this are:
* we get logs for *all* requests (including OPTIONS and HEADs), rather than
just those that end up hitting handlers we've remembered to decorate
correctly.
* when a request handler wires up a Producer (as the media stuff does
currently, and as other things will do soon), we log at the point that all
of the traffic has been sent to the client.
This code brings the SimpleHttpClient into line with the
MatrixFederationHttpClient by having it raise HttpResponseExceptions when a
request fails (rather than trying to parse for matrix errors and maybe raising
MatrixCodeMessageException).
Then, whenever we were checking for MatrixCodeMessageException and turning them
into SynapseErrors, we now need to check for HttpResponseExceptions and call
to_synapse_error.
We really shouldn't be sending all CodeMessageExceptions back over the C-S API;
it will include things like 401s which we shouldn't proxy.
That means that we need to explicitly turn a few HttpResponseExceptions into
SynapseErrors in the federation layer.
The effect of the latter is that the matrix errcode will get passed through
correctly to calling clients, which might help with some of the random
M_UNKNOWN errors when trying to join rooms.
We need to do a bit more validation when we get a server name, but don't want
to be re-doing it all over the shop, so factor out a separate
parse_and_validate_server_name, and do the extra validation.
Also, use it to verify the server name in the config file.
Make sure that server_names used in auth headers are sane, and reject them with
a sensible error code, before they disappear off into the depths of the system.
otherwise we explode with:
```
Traceback (most recent call last):
File /usr/lib/python2.7/logging/handlers.py, line 78, in emit
logging.FileHandler.emit(self, record)
File /usr/lib/python2.7/logging/__init__.py, line 950, in emit
StreamHandler.emit(self, record)
File /usr/lib/python2.7/logging/__init__.py, line 887, in emit
self.handleError(record)
File /usr/lib/python2.7/logging/__init__.py, line 810, in handleError
None, sys.stderr)
File /usr/lib/python2.7/traceback.py, line 124, in print_exception
_print(file, 'Traceback (most recent call last):')
File /usr/lib/python2.7/traceback.py, line 13, in _print
file.write(str+terminator)
File /home/matrix/.synapse/local/lib/python2.7/site-packages/twisted/logger/_io.py, line 170, in write
self.log.emit(self.level, format=u{log_io}, log_io=line)
File /home/matrix/.synapse/local/lib/python2.7/site-packages/twisted/logger/_logger.py, line 144, in emit
self.observer(event)
File /home/matrix/.synapse/local/lib/python2.7/site-packages/twisted/logger/_observer.py, line 136, in __call__
errorLogger = self._errorLoggerForObserver(brokenObserver)
File /home/matrix/.synapse/local/lib/python2.7/site-packages/twisted/logger/_observer.py, line 156, in _errorLoggerForObserver
if obs is not observer
File /home/matrix/.synapse/local/lib/python2.7/site-packages/twisted/logger/_observer.py, line 81, in __init__
self.log = Logger(observer=self)
File /home/matrix/.synapse/local/lib/python2.7/site-packages/twisted/logger/_logger.py, line 64, in __init__
namespace = self._namespaceFromCallingContext()
File /home/matrix/.synapse/local/lib/python2.7/site-packages/twisted/logger/_logger.py, line 42, in _namespaceFromCallingContext
return currentframe(2).f_globals[__name__]
File /home/matrix/.synapse/local/lib/python2.7/site-packages/twisted/python/compat.py, line 93, in currentframe
for x in range(n + 1):
RuntimeError: maximum recursion depth exceeded while calling a Python object
Logged from file site.py, line 129
File /usr/lib/python2.7/logging/__init__.py, line 859, in emit
msg = self.format(record)
File /usr/lib/python2.7/logging/__init__.py, line 732, in format
return fmt.format(record)
File /usr/lib/python2.7/logging/__init__.py, line 471, in format
record.message = record.getMessage()
File /usr/lib/python2.7/logging/__init__.py, line 335, in getMessage
msg = msg % self.args
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 4: ordinal not in range(128)
Logged from file site.py, line 129
```
...where the logger apparently recurses whilst trying to log the error, hitting the
maximum recursion depth and killing everything badly.
When we finish processing a request, log the number of events we fetched from
the database to handle it.
[I'm trying to figure out which requests are responsible for large amounts of
event cache churn. It may turn out to be more helpful to add counts to the
prometheus per-request/block metrics, but that is an extension to this code
anyway.]
(instead of everywhere that writes a response. Or rather, the subset of places
which write responses where we haven't forgotten it).
This also means that we don't have to have the mysterious version_string
attribute in anything with a request handler.
Unfortunately it does mean that we have to pass the version string wherever we
instantiate a SynapseSite, which has been c&ped 150 times, but that is code
that ought to be cleaned up anyway really.
This is useful in its own right, because server.py is full of stuff; but more
importantly, I want to do some refactoring that will cause a circular reference
as it is.
It is especially important that sync requests don't get cached, as if a
sync returns the same token given then the client will call sync with
the same parameters again. If the previous response was cached it will
get reused, resulting in the client tight looping making the same
request and never making any progress.
In general, clients will expect to get up to date data when requesting
APIs, and so its safer to do a blanket no cache policy than only
whitelisting APIs that we know will break things if they get cached.
It's useful to know when there are peaks in incoming requests - which isn't
quite the same as there being peaks in outgoing responses, due to the time
taken to handle requests.
