graphlog: document what "_" and "*" mean Documenting "*" should've been a part of 9b3f95d9783d, but I somehow didn't notice that the symbols are explained in the command's help text.

sshpeer: rename _recv and _send to _readframed and _writeframed Because it is reading and writing a chunk of data with a well-defined size. "recv" and "send" make it sound like things are a direct proxy to the underlying pipe, which they aren't. Differential Revision: https://phab.mercurial-scm.org/D2378

util: add a file object proxy that can read at most N bytes Sometimes we have data of a known size within a stream. For performance reasons, we don't want to pre-read this data (we want to allow consumers to read on demand). For simplicitly reasons, we don't want callers to necessarily know their data is coming from within an outer stream and there is a limit to how much they should read. The class introduced by this commit provides a very simple proxy around an underlying file object that allows the consumer to .read() up to N bytes from the file object. Attempts to read past this many bytes results in a simulated EOF. Differential Revision: https://phab.mercurial-scm.org/D2377

patches: release the GIL while applying the patch This will allow multiple threads to apply patches at the same time.

perfbranchmap: allow to select the filter to benchmark Running the branchmap computation on all filter levels can be expensive. Narrowing the run to some specific filters can speed up benchmarking time when working only on a subset of filter levels.

perfbranchmap: display 'unfiltered' for unfiltered performance This is slightly clearer than "None" and will help with coming changes to select the filter level we want timing for.