bug#64735: 29.0.92; find invocations are ~15x slower because of ignores

[Michael Albinus]

Ihor Radchenko <yantar92@posteo.net> writes:

Hi Ihor,

> May tramp only set file-name-handler-alist when a tramp command is
> actually invoked?

It's the other direction: Tramp is only invoked after a check in
file-name-handler-alist.

> Or, alternatively, may we fence the regexp matches in
> `file-name-handler-alist' behind boolean switches?
> I examined what the actual handlers do, and I can see
> `jka-compr-inhibit', `epa-inhibit', `tramp-archive-enabled',
> and `tramp-mode' are used to force-execute the original handler. If we
> could make Emacs perform these checks earlier, the whole expensive
> regexp matching phase could be bypassed.

Hmm, this would mean to extend the file-name-handler-alist spec. Instead
of a regexp to check, we would need to allow a function call or
alike. Don't know whether this pays for optimization.

And there is also the case, that due to inhibit-file-name-handlers and
inhibit-file-name-operation we can allow a remote file name operation
for a given function, and disable it for another function. Tramp uses
this mechanism. The general flag tramp-mode is not sufficient for this
scenario.

Best regards, Michael.