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;;; async.el --- Asynchronous processing in Emacs -*- lexical-binding: t -*-
;; Copyright (C) 2012-2016 Free Software Foundation, Inc.
;; Author: John Wiegley <jwiegley@gmail.com>
;; Created: 18 Jun 2012
;; Version: 1.9.2
;; Keywords: async
;; X-URL: https://github.com/jwiegley/emacs-async
;; This program is free software; you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation; either version 2, or (at
;; your option) any later version.
;; This program is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;; General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING. If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
;;; Commentary:
;; Adds the ability to call asynchronous functions and process with ease. See
;; the documentation for `async-start' and `async-start-process'.
;;; Code:
(defgroup async nil
"Simple asynchronous processing in Emacs"
:group 'emacs)
(defvar async-debug nil)
(defvar async-send-over-pipe t)
(defvar async-in-child-emacs nil)
(defvar async-callback nil)
(defvar async-callback-for-process nil)
(defvar async-callback-value nil)
(defvar async-callback-value-set nil)
(defvar async-current-process nil)
(defvar async--procvar nil)
(defun async-inject-variables
(include-regexp &optional predicate exclude-regexp)
"Return a `setq' form that replicates part of the calling environment.
It sets the value for every variable matching INCLUDE-REGEXP and
also PREDICATE. It will not perform injection for any variable
matching EXCLUDE-REGEXP (if present). It is intended to be used
as follows:
(async-start
`(lambda ()
(require 'smtpmail)
(with-temp-buffer
(insert ,(buffer-substring-no-properties (point-min) (point-max)))
;; Pass in the variable environment for smtpmail
,(async-inject-variables \"\\`\\(smtpmail\\|\\(user-\\)?mail\\)-\")
(smtpmail-send-it)))
'ignore)"
`(setq
,@(let (bindings)
(mapatoms
(lambda (sym)
(if (and (boundp sym)
(or (null include-regexp)
(string-match include-regexp (symbol-name sym)))
(not (string-match
(or exclude-regexp "-syntax-table\\'")
(symbol-name sym))))
(let ((value (symbol-value sym)))
(when (or (null predicate)
(funcall predicate sym))
(setq bindings (cons `(quote ,value) bindings)
bindings (cons sym bindings)))))))
bindings)))
(defalias 'async-inject-environment 'async-inject-variables)
(defun async-handle-result (func result buf)
(if (null func)
(progn
(set (make-local-variable 'async-callback-value) result)
(set (make-local-variable 'async-callback-value-set) t))
(unwind-protect
(if (and (listp result)
(eq 'async-signal (nth 0 result)))
(signal (car (nth 1 result))
(cdr (nth 1 result)))
(funcall func result))
(unless async-debug
(kill-buffer buf)))))
(defun async-when-done (proc &optional _change)
"Process sentinel used to retrieve the value from the child process."
(when (eq 'exit (process-status proc))
(with-current-buffer (process-buffer proc)
(let ((async-current-process proc))
(if (= 0 (process-exit-status proc))
(if async-callback-for-process
(if async-callback
(prog1
(funcall async-callback proc)
(unless async-debug
(kill-buffer (current-buffer))))
(set (make-local-variable 'async-callback-value) proc)
(set (make-local-variable 'async-callback-value-set) t))
(goto-char (point-max))
(backward-sexp)
(async-handle-result async-callback (read (current-buffer))
(current-buffer)))
(set (make-local-variable 'async-callback-value)
(list 'error
(format "Async process '%s' failed with exit code %d"
(process-name proc) (process-exit-status proc))))
(set (make-local-variable 'async-callback-value-set) t))))))
(defun async--receive-sexp (&optional stream)
(let ((sexp (decode-coding-string (base64-decode-string
(read stream)) 'utf-8-unix))
;; Parent expects UTF-8 encoded text.
(coding-system-for-write 'utf-8-unix))
(if async-debug
(message "Received sexp {{{%s}}}" (pp-to-string sexp)))
(setq sexp (read sexp))
(if async-debug
(message "Read sexp {{{%s}}}" (pp-to-string sexp)))
(eval sexp)))
(defun async--insert-sexp (sexp)
(let (print-level
print-length
(print-escape-nonascii t)
(print-circle t))
(prin1 sexp (current-buffer))
;; Just in case the string we're sending might contain EOF
(encode-coding-region (point-min) (point-max) 'utf-8-unix)
(base64-encode-region (point-min) (point-max) t)
(goto-char (point-min)) (insert ?\")
(goto-char (point-max)) (insert ?\" ?\n)))
(defun async--transmit-sexp (process sexp)
(with-temp-buffer
(if async-debug
(message "Transmitting sexp {{{%s}}}" (pp-to-string sexp)))
(async--insert-sexp sexp)
(process-send-region process (point-min) (point-max))))
(defun async-batch-invoke ()
"Called from the child Emacs process' command-line."
;; Make sure 'message' and 'prin1' encode stuff in UTF-8, as parent
;; process expects.
(let ((coding-system-for-write 'utf-8-unix))
(setq async-in-child-emacs t
debug-on-error async-debug)
(if debug-on-error
(prin1 (funcall
(async--receive-sexp (unless async-send-over-pipe
command-line-args-left))))
(condition-case err
(prin1 (funcall
(async--receive-sexp (unless async-send-over-pipe
command-line-args-left))))
(error
(prin1 (list 'async-signal err)))))))
(defun async-ready (future)
"Query a FUTURE to see if it is ready.
I.e., if no blocking
would result from a call to `async-get' on that FUTURE."
(and (memq (process-status future) '(exit signal))
(let ((buf (process-buffer future)))
(if (buffer-live-p buf)
(with-current-buffer buf
async-callback-value-set)
t))))
(defun async-wait (future)
"Wait for FUTURE to become ready."
(while (not (async-ready future))
(sleep-for 0.05)))
(defun async-get (future)
"Get the value from process FUTURE when it is ready.
FUTURE is returned by `async-start' or `async-start-process' when
its FINISH-FUNC is nil."
(and future (async-wait future))
(let ((buf (process-buffer future)))
(when (buffer-live-p buf)
(with-current-buffer buf
(async-handle-result
#'identity async-callback-value (current-buffer))))))
(defun async-message-p (value)
"Return true of VALUE is an async.el message packet."
(and (listp value)
(plist-get value :async-message)))
(defun async-send (&rest args)
"Send the given messages to the asychronous Emacs PROCESS."
(let ((args (append args '(:async-message t))))
(if async-in-child-emacs
(if async-callback
(funcall async-callback args))
(async--transmit-sexp (car args) (list 'quote (cdr args))))))
(defun async-receive ()
"Send the given messages to the asychronous Emacs PROCESS."
(async--receive-sexp))
;;;###autoload
(defun async-start-process (name program finish-func &rest program-args)
"Start the executable PROGRAM asynchronously. See `async-start'.
PROGRAM is passed PROGRAM-ARGS, calling FINISH-FUNC with the
process object when done. If FINISH-FUNC is nil, the future
object will return the process object when the program is
finished. Set DEFAULT-DIRECTORY to change PROGRAM's current
working directory."
(let* ((buf (generate-new-buffer (concat "*" name "*")))
(proc (let ((process-connection-type nil))
(apply #'start-process name buf program program-args))))
(with-current-buffer buf
(set (make-local-variable 'async-callback) finish-func)
(set-process-sentinel proc #'async-when-done)
(unless (string= name "emacs")
(set (make-local-variable 'async-callback-for-process) t))
proc)))
(defvar async-quiet-switch "-Q"
"The Emacs parameter to use to call emacs without config.
Can be one of \"-Q\" or \"-q\".
Default is \"-Q\" but it is sometimes useful to use \"-q\" to have a
enhanced config or some more variables loaded.")
;;;###autoload
(defun async-start (start-func &optional finish-func)
"Execute START-FUNC (often a lambda) in a subordinate Emacs process.
When done, the return value is passed to FINISH-FUNC. Example:
(async-start
;; What to do in the child process
(lambda ()
(message \"This is a test\")
(sleep-for 3)
222)
;; What to do when it finishes
(lambda (result)
(message \"Async process done, result should be 222: %s\"
result)))
If FINISH-FUNC is nil or missing, a future is returned that can
be inspected using `async-get', blocking until the value is
ready. Example:
(let ((proc (async-start
;; What to do in the child process
(lambda ()
(message \"This is a test\")
(sleep-for 3)
222))))
(message \"I'm going to do some work here\") ;; ....
(message \"Waiting on async process, result should be 222: %s\"
(async-get proc)))
If you don't want to use a callback, and you don't care about any
return value from the child process, pass the `ignore' symbol as
the second argument (if you don't, and never call `async-get', it
will leave *emacs* process buffers hanging around):
(async-start
(lambda ()
(delete-file \"a remote file on a slow link\" nil))
'ignore)
Note: Even when FINISH-FUNC is present, a future is still
returned except that it yields no value (since the value is
passed to FINISH-FUNC). Call `async-get' on such a future always
returns nil. It can still be useful, however, as an argument to
`async-ready' or `async-wait'."
(let ((sexp start-func)
;; Subordinate Emacs will send text encoded in UTF-8.
(coding-system-for-read 'utf-8-unix))
(setq async--procvar
(async-start-process
"emacs" (file-truename
(expand-file-name invocation-name
invocation-directory))
finish-func
async-quiet-switch "-l"
;; Using `locate-library' ensure we use the right file
;; when the .elc have been deleted.
(locate-library "async")
"-batch" "-f" "async-batch-invoke"
(if async-send-over-pipe
"<none>"
(with-temp-buffer
(async--insert-sexp (list 'quote sexp))
(buffer-string)))))
(if async-send-over-pipe
(async--transmit-sexp async--procvar (list 'quote sexp)))
async--procvar))
(defmacro async-sandbox(func)
"Evaluate FUNC in a separate Emacs process, synchronously."
`(async-get (async-start ,func)))
(defun async--fold-left (fn forms bindings)
(let ((res forms))
(dolist (binding bindings)
(setq res (funcall fn res
(if (listp binding)
binding
(list binding)))))
res))
(defmacro async-let (bindings &rest forms)
"Implements `let', but each binding is established asynchronously.
For example:
(async-let ((x (foo))
(y (bar)))
(message \"%s %s\" x y))
expands to ==>
(async-start (foo)
(lambda (x)
(async-start (bar)
(lambda (y)
(message \"%s %s\" x y)))))"
(declare (indent 1))
(async--fold-left
(lambda (acc binding)
(let ((fun (pcase (cadr binding)
((and (pred functionp) f) f)
(f `(lambda () ,f)))))
`(async-start ,fun
(lambda (,(car binding))
,acc))))
`(progn ,@forms)
(reverse bindings)))
(provide 'async)
;;; async.el ends here