revlog: rename 'self.checkinlinesize' into '_enforceinlinesize' The name change has two motivations: 1) The function has no external caller, so we move it to protected space. 2) the function does more than checking it also split the data if we have more data than 'inline' supports.

revlog: add a _datareadfp context manager for data access needs The helper handles: 1) is there a file handle already open that we shall just reuse, 2) is the revlog inlined or not. Using a context manager for all read access will help setting up file pointer caching in later changesets.

revlog: use context manager for data file lifetime in checksize This is clearer, safer and more modern.

revlog: use context manager for index file lifetime in checkinlinesize This is clearer, safer and more modern.

revlog: use context manager for data file lifetime in checkinlinesize This is clearer, safer and more modern.

revlog: use context manager for index file life time in __init__ This is clearer, safer and more modern.

revlog: move index file opening in a method Having file operation centralized into a single spot help to factor common logic out (eg: special flag handling according to the mode). It is also the first step to simplify file handling during batch operation (eg: revlog cloning). However, that part does not seems to be a hotspot yet.

revlog: move datafile opening in a method Having file operation centralized into a single spot help to factor common logic out. It is also the first step to simplify file handling during batch operation (eg: revlog cloning). However, that part does not seems to be a hotspot yet.

parseindex: implement context manager method on the wrapper This is needed for incoming cleanups.

parseindex: also forward keyword argument in a debug wrapper Otherwise, it gets in the way of a coming refactoring.