cborutil: change buffering strategy
Profiling revealed that we were spending a lot of time on the
line that was concatenating the old buffer with the incoming data
when attempting to decode long byte strings, such as manifest
revisions.
Essentially, we were feeding N chunks of size len(X) << len(Y) into
decode() and continuously allocating a new, larger buffer to hold
the undecoded input. This created substantial memory churn and
slowed down execution.
Changing the code to aggregate pending chunks in a list until we
have enough data to fully decode the next atom makes things much
more efficient.
I don't have exact data, but I recall the old code spending >1s
on manifest fulltexts from the mozilla-unified repo. The new code
doesn't significantly appear in profile output.
Differential Revision: https://phab.mercurial-scm.org/D4854
*** Test in-uri schemes
CFG: {b'x.prefix': b'http://example.org'}
URI: http://example.org/foo
('x', 'x')
URI: http://example.org/foo/bar
('x', 'x')
URI: http://example.org/bar
('x', 'x')
URI: https://example.org/foo
abort
URI: https://example.org/foo/bar
abort
URI: https://example.org/bar
abort
URI: https://x@example.org/bar
abort
URI: https://y@example.org/bar
abort
CFG: {b'x.prefix': b'https://example.org'}
URI: http://example.org/foo
abort
URI: http://example.org/foo/bar
abort
URI: http://example.org/bar
abort
URI: https://example.org/foo
('x', 'x')
URI: https://example.org/foo/bar
('x', 'x')
URI: https://example.org/bar
('x', 'x')
URI: https://x@example.org/bar
('x', 'x')
URI: https://y@example.org/bar
abort
CFG: {b'x.prefix': b'http://example.org', b'x.schemes': b'https'}
URI: http://example.org/foo
('x', 'x')
URI: http://example.org/foo/bar
('x', 'x')
URI: http://example.org/bar
('x', 'x')
URI: https://example.org/foo
abort
URI: https://example.org/foo/bar
abort
URI: https://example.org/bar
abort
URI: https://x@example.org/bar
abort
URI: https://y@example.org/bar
abort
CFG: {b'x.prefix': b'https://example.org', b'x.schemes': b'http'}
URI: http://example.org/foo
abort
URI: http://example.org/foo/bar
abort
URI: http://example.org/bar
abort
URI: https://example.org/foo
('x', 'x')
URI: https://example.org/foo/bar
('x', 'x')
URI: https://example.org/bar
('x', 'x')
URI: https://x@example.org/bar
('x', 'x')
URI: https://y@example.org/bar
abort
*** Test separately configured schemes
CFG: {b'x.prefix': b'example.org', b'x.schemes': b'http'}
URI: http://example.org/foo
('x', 'x')
URI: http://example.org/foo/bar
('x', 'x')
URI: http://example.org/bar
('x', 'x')
URI: https://example.org/foo
abort
URI: https://example.org/foo/bar
abort
URI: https://example.org/bar
abort
URI: https://x@example.org/bar
abort
URI: https://y@example.org/bar
abort
CFG: {b'x.prefix': b'example.org', b'x.schemes': b'https'}
URI: http://example.org/foo
abort
URI: http://example.org/foo/bar
abort
URI: http://example.org/bar
abort
URI: https://example.org/foo
('x', 'x')
URI: https://example.org/foo/bar
('x', 'x')
URI: https://example.org/bar
('x', 'x')
URI: https://x@example.org/bar
('x', 'x')
URI: https://y@example.org/bar
abort
CFG: {b'x.prefix': b'example.org', b'x.schemes': b'http https'}
URI: http://example.org/foo
('x', 'x')
URI: http://example.org/foo/bar
('x', 'x')
URI: http://example.org/bar
('x', 'x')
URI: https://example.org/foo
('x', 'x')
URI: https://example.org/foo/bar
('x', 'x')
URI: https://example.org/bar
('x', 'x')
URI: https://x@example.org/bar
('x', 'x')
URI: https://y@example.org/bar
abort
*** Test prefix matching
CFG: {b'x.prefix': b'http://example.org/foo', b'y.prefix': b'http://example.org/bar'}
URI: http://example.org/foo
('x', 'x')
URI: http://example.org/foo/bar
('x', 'x')
URI: http://example.org/bar
('y', 'y')
URI: https://example.org/foo
abort
URI: https://example.org/foo/bar
abort
URI: https://example.org/bar
abort
URI: https://x@example.org/bar
abort
URI: https://y@example.org/bar
abort
CFG: {b'x.prefix': b'http://example.org/foo', b'y.prefix': b'http://example.org/foo/bar'}
URI: http://example.org/foo
('x', 'x')
URI: http://example.org/foo/bar
('y', 'y')
URI: http://example.org/bar
abort
URI: https://example.org/foo
abort
URI: https://example.org/foo/bar
abort
URI: https://example.org/bar
abort
URI: https://x@example.org/bar
abort
URI: https://y@example.org/bar
abort
CFG: {b'x.prefix': b'*', b'y.prefix': b'https://example.org/bar'}
URI: http://example.org/foo
abort
URI: http://example.org/foo/bar
abort
URI: http://example.org/bar
abort
URI: https://example.org/foo
('x', 'x')
URI: https://example.org/foo/bar
('x', 'x')
URI: https://example.org/bar
('y', 'y')
URI: https://x@example.org/bar
('x', 'x')
URI: https://y@example.org/bar
('y', 'y')
*** Test user matching
CFG: {b'x.password': b'xpassword', b'x.prefix': b'http://example.org/foo', b'x.username': None}
URI: http://y@example.org/foo
('y', 'xpassword')
CFG: {b'x.password': b'xpassword', b'x.prefix': b'http://example.org/foo', b'x.username': None, b'y.password': b'ypassword', b'y.prefix': b'http://example.org/foo', b'y.username': b'y'}
URI: http://y@example.org/foo
('y', 'ypassword')
CFG: {b'x.password': b'xpassword', b'x.prefix': b'http://example.org/foo/bar', b'x.username': None, b'y.password': b'ypassword', b'y.prefix': b'http://example.org/foo', b'y.username': b'y'}
URI: http://y@example.org/foo/bar
('y', 'xpassword')
*** Test urllib2 and util.url
URIs: http://user@example.com:8080/foo http://example.com:8080/foo
('user', '')