Re: [QUESTION] Re: [PATCH] make org-attach-url download function as an option

[Ihor Radchenko <yantar92@gmail.com>]

> Indeed, as long as org-attach introduced new async actions. Those hooks will
> have problem if they requires files is downloading finished. Also `make-thread'
> does not have process sentinel. That's also an problem.
>
> Does anyone have better idea?

You can wrap the call to org-attach-url-function into with-mutex and run
hooks in another thread ustilising the same mutex.
Note that the heading contents (including :DIR: property), point,
current buffer, and window might be changed at the time the hook thread
will be called. You will need to perform some sanity checks and
potentially cleanup after org-attach-url-function if the heading was
modified in some undesired way.

The above assumes that org-attach-url-function returns after the file is
attached. This might not be the case if org-attach-url-function calls
async shell command. This should be either documented or also handled in
some way.

Best,
Ihor

stardiviner <numbchild@gmail.com> writes:

> Ihor Radchenko <yantar92@gmail.com> writes:
>
>> I do not know an answer to your question, but would like to point out
>> that make-thread will return immidietealy and all the following code
>> will run before the download finishes:
>>
>> (run-hook-with-args 'org-attach-after-change-hook attach-dir)
>> (org-attach-tag)
>> (cond ((eq org-attach-store-link-p 'attached)...
>>
>> At least the hooks and org-attach-tag would expect that the file is
>> attached already.
>
> Indeed, as long as org-attach introduced new async actions. Those hooks will
> have problem if they requires files is downloading finished. Also `make-thread'
> does not have process sentinel. That's also an problem.
>
> Does anyone have better idea?
>
>>
>> Best,
>> Ihor
>>
>> stardiviner <numbchild@gmail.com> writes:
>>
>>> I got solution for async org-attach-url now. Use `make-thread` for async
>>> downloading is simple.
>>>
>>> Here is the code prototype, but it has a problem, seems `apply` part code does
>>> not really downloading file. I don't know why. Does anybody knows the reason?
>>>
>>> #+begin_src diff
>>> modified   lisp/org-attach.el
>>> @@ -110,6 +110,12 @@ (defcustom org-attach-method 'cp
>>>  	  (const :tag "Hard Link" ln)
>>>  	  (const :tag "Symbol Link" lns)))
>>>  
>>> +(defcustom org-attach-url-function 'url-copy-file
>>> +  "The download file function to use in org-attach-url."
>>> +  :type '(choice (const 'url-copy-file))
>>> +  :safe #'functionp
>>> +  :group 'org-attach)
>>> +
>>>  (defcustom org-attach-expert nil
>>>    "Non-nil means do not show the splash buffer with the attach dispatcher."
>>>    :group 'org-attach
>>> @@ -503,7 +509,12 @@ (defun org-attach-attach (file &optional visit-dir method)
>>>         ((eq method 'cp) (copy-file file attach-file))
>>>         ((eq method 'ln) (add-name-to-file file attach-file))
>>>         ((eq method 'lns) (make-symbolic-link file attach-file))
>>> -       ((eq method 'url) (url-copy-file file attach-file)))
>>> +       ((eq method 'url) (make-thread
>>> +			  (lambda ()
>>> +			    ;; (url-copy-file file attach-file)
>>> +			    ;; FIXME This seems does not really download file. Don't know why.
>>> +			    (apply org-attach-url-function '(file attach-file)))
>>> +			  "org-attach-url downloading")))
>>>        (run-hook-with-args 'org-attach-after-change-hook attach-dir)
>>>        (org-attach-tag)
>>>        (cond ((eq org-attach-store-link-p 'attached)
>>> #+end_src
>>>
>>> Bastien <bzg@gnu.org> writes:
>>>
>>>> Hi,
>>>>
>>>> stardiviner <numbchild@gmail.com> writes:
>>>>
>>>>> I found when network is bad and slow, or the download file is big, the
>>>>> org-attach-url will suspend Emacs for a long time. User might have to cancel
>>>>> downloading, and start again later.
>>>>
>>>> Indeed, this might be annoying.  At the same time, it is not
>>>> unreasonable to expect the user to know what size is the contents he
>>>> is willing to attach to an Org node.
>>>>
>>>>> I hope to make "org-attach-url" download file asynchronously. But function
>>>>> org-attach-attach hardcoded this function for 'url method. Here is a patch to
>>>>> make it into an option.
>>>>
>>>> (FWIW, I could not find the patch.)
>>>>
>>>> I think you are on the right track when trying to enhance the 'url
>>>> package.  Maybe url-copy-file should be asynchronous and url could
>>>> provide url-copy-file-synchronously (to mimic the url-retrieve and
>>>> url-retrieve-synchronously pair)?
>>>>
>>>> Until Emacs has a function to copy a URL's contents asynchronously,
>>>> I'd rather not add this functionality in Org.
>>>
>>>
>>> -- 
>>> [ stardiviner ]
>>>        I try to make every word tell the meaning that I want to express.
>>>
>>>        Blog: https://stardiviner.github.io/
>>>        IRC(freenode): stardiviner, Matrix: stardiviner
>>>        GPG: F09F650D7D674819892591401B5DF1C95AE89AC3
>>>
>
>
> -- 
> [ stardiviner ]
>        I try to make every word tell the meaning that I want to express.
>
>        Blog: https://stardiviner.github.io/
>        IRC(freenode): stardiviner, Matrix: stardiviner
>        GPG: F09F650D7D674819892591401B5DF1C95AE89AC3
>

-- 
Ihor Radchenko,
PhD,
Center for Advancing Materials Performance from the Nanoscale (CAMP-nano)
State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China
Email: yantar92@gmail.com, ihor_radchenko@alumni.sutd.edu.sg