Tuesday, July 03, 2018

Using Emacs Threads To Execute Commands Asynchronously

Using Emacs Threads To Execute Commands Asynchronously

1 Executive Summary

Emacs 26 has threads for executing functions asynchronously. Emacs
commands that call an external process and wait for that process to
finish make a good candidate for asynchronous execution — e.g.,
smtpmail-send-it for sending mail. The arrival of threads provides
an interesting option for running such commands asynchronously.



2 First Attempt — Custom Async gnus Command

I initially wrote a custom command for launching gnus asynchronously
— it was a one-line function that ran the following:

(make-thread #'gnus)

The above worked well — except when command gnus needed user input
— so I just had to be thoughtful about when I called it. But a few
weeks later, I wanted the equivalent for function smtpmail-send-it
for sending mail. I almost wrote myself one more command before
stepping back to create a more generic solution.


3 One Command To Thread Them All

I have now defined command emacspeak-wizards-execute-asynchronously
bound to C-' a.
Note that this command, though part of module emacspeak-wizards, has
no emacspeak dependencies.


(defun emacspeak-wizards-execute-asynchronously (key)
  "Read key-sequence, then execute its command on a new thread."
  (interactive (list (read-key-sequence "Key Sequence: ")))
      (let ((l  (local-key-binding key))
             (g (global-key-binding key)))
    (cond
     ( (commandp l)
       (make-thread l)
      (message "Running %s on a new thread." l))
     ((commandp g)
      (make-thread g)
      (message "Running %s on a new thread." g))
     (t (error "%s is not bound to a command." key)))))

(global-set-key (kbd "C-' a") 'emacspeak-wizards-execute-asynchronously)

With this command bound to C-' a, I can now get rid of my custom
gnus-async command and its associated key-binding. I already have
command gnus bound to C-; g, so I can just press C-' a C-; g to
fetch news/mail asynchronously.


Similarly, when sending mail using smtpmail I can press C-' a C-c
C-c
in the *mail* buffer to send mail without Emacs blocking.


4 Final Caveats

Like other asynchronous solutions (see package async for instance)
one needs to make sure that the command being executed asynchronously
will not require user input. In the case of package async, the
asynchronous Emacs will block waiting for input; in the case of
make-thread, Emacs enters a blocking loop with the minibuffer
continuously displaying

No catch for ...

The only way to come out is to kill Emacs — so make sure to use
command emacspeak-wizards-execute-asynchronously only when you're
sure that the command being run asynchronously will not require user
input.

Date: 2018-07-03 Tue 00:00

Author: T.V Raman

Created: 2018-07-03 Tue 14:37

Validate



Friday, June 22, 2018

Effective Suggest And Complete In An Eyes-Free Environment

Effective Suggest And Complete In An Eyes-Free Environment

1 Executive Summary

Emacs has always provided a wealth of techniques for rapid keyboard
input (abbrev, dabbrev, hippie-expandand completion come to mind)
alongside a rich collection of tools for navigating among open
buffers. And these affordances have significantly increased over the
last few years with the arrival of packages like ido, company,
helm etc., each replete with different strategies for rapid task
completion such as flex and fuzzy matching. This article investigates
these tools in an eyes-free environment, specifically in the context
of Emacspeak and rapid task completion. I've not investigated every
possible package in this space — instead, I've picked a collection
of packages and techniques that have worked well in an eyes-free
context. Finally, the ultimate metric I use in each case is the time
to successful task completion — since at the end of the day, that's
the only metric that counts when it comes to user productivity.


2 Terminology

For this article, I will use terms suggestion and completion to
mean subtly different concepts. I'll also use terms explore and
filter in describing various phases in user interaction.


Suggestion
Offer the user some suggestions that help explore the space of choices. (metaphor: avoid the blank sheet of paper syndrome).
Completion
Filter the available choices based on user input with the goal of reaching the target as rapidly as possible.
Explore
User does not necessarily know what he is looking for, but expects to be able to recognize what he wants from the displayed choices.
Target
User knows exactly what he wants, e.g., filename, or function-name, but would still like to get there with the fewest possible number of keystrokes, along with the needed memory aids to guide the decision.


Note that in practice, suggestions and completions work
hand-in-hand, with the visual display playing a central role in
guiding the user through the pace of available choices. In a typical
user interaction session, the space of suggestions gets filtered by
user input to produce the available completions (choices) for the next
round of user input — think of this as a
Suggest/Input/Filter/Target (SIFT) interaction loop. Similarly, explore and
target type activities typically go hand-in-hand, with explore
serving as a memory-aid for locating the target.



3 Tasks Where Suggestions And Completions Help Speed Up Task Completion

Here are exemplars of tasks that I perform often and where I require
all the help that Emacs can provide in completing the task as rapidly
as possible:


File Navigation
Navigating to and opening a file — either code or prose.
Content Navigation
Jump to a specific location (section, function, class/method, or pattern-match) in that file.
Buffer Navigation
Jump to an already open buffer in a long-running Emacs.

If that buffer existed — but has since been killed (by
midnight for example), then re-open that buffer.
I do everything in Emacs, so open buffers include a large
number of ORG and LaTeX documents, Web Pages opened in EWW
(news sites, documentation, blog articles), IM Chats (I use
jabber), Mail Buffers — both open folders and previously
sent messages, and much, much more.

Media
Easily launch media streams including local and streaming media.
EBooks
Open (or jump to an already open) EBook to continue reading.
Code Completion
Complete function/method-name as I type, with an easy affordance to move among the available choices. The Suggest/Input/Filter/Target interaction loop applies here as well.


Notice that as one performs all of these tasks, every target is an
Emacs buffer or Emacs buffer location. In the case of completion, the
target is a string that gets inserted at the current location.


4 Features Of Eyes-Free Interaction

Using spoken output — as opposed to a rich visual display — has
the following special features and/or drawbacks:


  1. A large visual display can offer the user many choices at a time,
    and the eye's ability to rapidly scan these choices makes for an
    extremely fast Suggest/Input/Filter/Target loop. As an example, an
    interface like helm can display a large number of initial
    choices, with the user filtering these down with a few strategic key-presses.
  2. Spoken output takes time — and there is simply no way around
    this — speeding up speech-rate helps to a point, but speaking
    50 choices very fast does not help the user in the explore
    phase. This means that effective filtering and ranking of the available
    choices takes on added importance.
  3. More importantly, picking a Suggest/Input/Filter/Target (SIFT)
    interaction loop that depends on a large display is sub-optimal
    for eyes-free interaction.
  4. Given (2,3), smart filtering, flex/fuzzy matching, and ranking
    based on past user behavior take on added importance in an
    eyes-free environment. As an aside, I have high hopes in this
    area for package prescient — though in my few days of usage,
    it has yet to make a difference in my productivity.
  5. For many of the tasks enumerated in the previous section, (2, 3
    and 4) make ido with flex and fuzzy matching extremely
    effective. In contrast, helm with similar flex and fuzzy
    matching (via packages helm-flx and helm-fuzzier) adds little
    extra benefit — and the fractional extra time to compute and
    display the choices can even lead to a minor productivity hit.
  6. When it comes to writing code with completion, package company
    has proven extremely effective. Notice that when writing code,
    one rarely if ever resorts to fuzzy matching — this may well
    be subjective. Speaking for myself, I cannot think of function
    or method names in the context of fuzzy matching — said
    differently, it's hard to think xl for function-name
    next-line — even though in a given filtering context, xl
    might define the shortest path through the available choices to
    the target next-line. Given this, emacspeak implements a
    company front-end that allows the user to navigate through the
    available choices with succinct spoken feedback, and I use those
    choices only after I have typed sufficiently many characters to
    have a manageable number of choices — said differently, though
    package company is set up to trigger after 3 characters have
    been typed, I usually end up typing more — and often resort to
    dabbrev or hippee-expand to input this longer prefix.
  7. Some of the shortcomings with eyes-free interaction enumerated
    above lead to my looking for effective work-arounds that might
    well work well outside the eyes-free context, e.g. when the
    available choices are too large to fit on a typical visual
    display. Interestingly, most of these have also been solved by
    mainstream Emacs developers in their never-ending/unerring quest for increased
    productivity — package ido and company are excellent exemplars.


  • Mapping Solutions To Tasks

This section maps the various solutions I use to speed up the tasks
enumerated earlier in this article.


4.1 File And Buffer Navigation

I use package ido with add-ons flx-ido and ido-completing-read+
(formerly ido-ubiquitous) as my primary/only solution for this
task. I've dabbled with package helm — primarily via command
helm-mini but have found almost no use-cases where I did better with
helm. I also use command org-switchb to quickly jump to any of my
open org buffers – since that automatically filters the choices
down for me — I can then get to the org-mode buffer I want with
one or two keystrokes. Notice that in all of these cases, I'm relying
on the fact that I mostly know what I want, i.e., the explore phase
does not start with an entirely blank sheet of paper.


4.2 Content Navigation

Incremental search is your biggest and most effective friend in
effective eyes-free interaction — this simply cannot be stressed
enough. That everything in Emacs is searchable via
incremental-search is a big win for eyes-free interaction. When you
have a large visual display, the human eye is the search interface of
first resort – you typically use a search-command only if the
target is below the fold or far away from the cursor. Because spoken
output takes time, I use isearch even when the target is one or two
lines away.


Structured navigation comes next in my toolbox for navigating content
imenu for code, and section navigation for documents (org,
LaTeX). I also use command occur to advantage since that provides a
quick way of finding all the desired targets in a document. Given that
program source-code uses indentation for displaying structure,
hbuilt-in command selective-display remains one of Emacs' hidden
treasures with respect to expanding/collapsing source-code.


Finally, I
use a combination of isearch and structured navigation in
org-mode buffres by collapsing the document, and then using
isearch to reveal the desired content fragment.
In the case of LaTeX documents, I use package reftex to
generate a navigation buffer that functions as an interactive table
of contents.


4.3 Locating And Playing Media

  1. I keep all my music content organized under ~/mp3.
  2. I keep playlist files that contain stream-links to my favorite
    Internet streams under emacspeak/media.
  3. The afore-mentioned techniques using ido enables me to launch
    local and streaming media with a small number of keystrokes. Once
    selected, the content is played via package emacspeak-m-player
    which provides Emacs bindings to all mplayer functionality
    via that program's slave-mode. In addition, Emacspeak also
    implements a smart emacspeak-m-player-locate-media which uses
    Emacs' integration with command locate to turn the located
    files matching a given pattern into an interactive play-list.

4.4 EBooks

Jumping to already open ebooks is no different than buffer
navigation. I organize all my ebooks under a single directory
tree, and module emacspeak-epub implements a bookshelf that
allows me to organize and browse my collection along various
axies. Finally, Emacspeak implements a light-weight bookmark
facility that works with eww so that I can save my place in an
ebook across Emacs sessions.


4.5 Code Completion

As covered earlier, I use company along with dabbrev and
hippee-expand while writing code. I also use yasnippet to
generate skeleton code. I use auto-correct-mode to
automatically correct repeated errors, and add abbrevs for
commonly occurring typos.


5 Summary

  1. Emacs' Suggest/Input/Filter/Target (SIFT) interaction loop is just as
    effective in eyes-free interaction — in fact more so .
  2. Fuzzy matching when filtering is a big win when working with spoken
    output — it leads to faster task completion.
  3. Navigating ones computing environment based on the underlying
    structure and semantics of electronic content is a major win —
    both when working with a visual or spoken display. The advantages
    just become evident far sooner in the eyes-free context due to the
    inherently temporal nature of spoken interaction.

Date: 2018-06-22 Fri 00:00

Author: T.V Raman

Created: 2018-06-23 Sat 17:22

Validate

Thursday, May 03, 2018

Emacspeak 48.0 (ServiceDog) Unleashed!

Emacspeak 48.0—ServiceDog—Unleashed!

*For Immediate Release:


San Jose, Calif., (May 04, 2018)


Emacspeak 48.0 (ServiceDog):
Redefining Accessibility In The Age Of User-Aware Interfaces
–Zero cost of Ownership makes priceless software Universally affordable!


Emacspeak Inc (NASDOG: ESPK) — http://github.com/tvraman/emacspeak
— announces the immediate world-wide availability of Emacspeak 48.0
(ServiceDog) — a powerful audio desktop for leveraging today's
evolving Data, Social and Assistant-Oriented Internet cloud.


1 Investors Note:

With several prominent tweeters expanding coverage of #emacspeak,
NASDOG: ESPK has now been consistently trading over the social net at
levels close to that once attained by DogCom high-fliers—and as of
May
2018 is trading at levels close to that achieved by once better known
stocks in the tech sector.


2 What Is It?

Emacspeak is a fully functional audio desktop that provides complete
eyes-free access to all major 32 and 64 bit operating environments. By
seamlessly blending live access to all aspects of the Internet such as
ubiquitous assistance, Web-surfing, blogging, social computing and
electronic messaging into the audio desktop, Emacspeak enables speech
access to local and remote information with a consistent and
well-integrated user interface. A rich suite of task-oriented tools
provides efficient speech-enabled access to the evolving
assistant-oriented social Internet cloud.


3 Major Enhancements:

This version requires emacs-25.1 or later.

  1. Emacs 26 Support 🤻
  1. Locate And Play Media ᭳
  2. Updated EPub Support 🕮
  3. Updated Outloud TTS Server 💬
  4. Espeak-NG support📢
  5. Smart TTS Prompts 🙊
  6. DBus Integration including screenlock via Gnome-ScreenSaver 🚌
  7. MPlayer And Equalizer Presets ≝
  8. VLC front-end 🎹
  9. Updated URL templates 🕷
  10. Updated websearch wizards 🕸


    — And a lot more than will fit this margin. … 🗞



4 Establishing Liberty, Equality And Freedom:

Never a toy system, Emacspeak is voluntarily bundled with all
major Linux distributions. Though designed to be modular,
distributors have freely chosen to bundle the fully integrated
system without any undue pressure—a documented success for
the integrated innovation embodied by Emacspeak. As the system
evolves, both upgrades and downgrades continue to be available at
the same zero-cost to all users. The integrity of the Emacspeak
codebase is ensured by the reliable and secure Linux platform
used to develop and distribute the software.


Extensive studies have shown that thanks to these features, users
consider Emacspeak to be absolutely priceless. Thanks to this
wide-spread user demand, the present version remains priceless
as ever—it is being made available at the same zero-cost as
previous releases.


At the same time, Emacspeak continues to innovate in the area of
eyes-free Assistance and social interaction and carries forward the
well-established Open Source tradition of introducing user interface
features that eventually show up in luser environments.


On this theme, when once challenged by a proponent of a crash-prone
but well-marketed mousetrap with the assertion "Emacs is a system from
the 70's", the creator of Emacspeak evinced surprise at the unusual
candor manifest in the assertion that it would take popular
idiot-proven interfaces until the year 2070 to catch up to where the
Emacspeak audio desktop is today. Industry experts welcomed this
refreshing breath of Courage Certainty and Clarity (CCC) at a time
when users are reeling from the Fear Uncertainty and Doubt (FUD)
unleashed by complex software systems backed by even more convoluted
press releases.


5 Independent Test Results:

Independent test results have proven that unlike some modern (and
not so modern) software, Emacspeak can be safely uninstalled without
adversely affecting the continued performance of the computer. These
same tests also revealed that once uninstalled, the user stopped
functioning altogether. Speaking with Aster Labrador, the creator of
Emacspeak once pointed out that these results re-emphasize the
user-centric design of Emacspeak; “It is the user –and not the
computer– that stops functioning when Emacspeak is uninstalled!”.


5.1 Note from Aster,Bubbles and Tilden:

UnDoctored Videos Inc. is looking for volunteers to star in a
video demonstrating such complete user failure.


6 Obtaining Emacspeak:

Emacspeak can be downloaded from GitHub –see
https://github.com/tvraman/emacspeak you can visit Emacspeak on the
WWW at http://emacspeak.sf.net. You can subscribe to the emacspeak
mailing list — emacspeak@cs.vassar.edu — by sending mail to the
list request address emacspeak-request@cs.vassar.edu. The Emacspeak
Blog
is a good source for news about recent enhancements and how to
use them.


The latest development snapshot of Emacspeak is always available via
Git from GitHub at
Emacspeak GitHub .


7 History:

  • Emacspeak 48.0 (ServiceDog) builds on earlier releases to provide
    continued end-user value.
  • Emacspeak 47.0 (GentleDog) goes the next step in being helpful
    while letting users learn and grow.
  • Emacspeak 46.0 (HelpfulDog) heralds the coming of Smart Assistants.
  • Emacspeak 45.0 (IdealDog) is named in recognition of Emacs'
    excellent integration with various programming language
    environments — thanks to this, Emacspeak is the IDE of choice
    for eyes-free software engineering.
  • Emacspeak 44.0 continues the steady pace of innovation on the
    audio desktop.
  • Emacspeak 43.0 brings even more end-user efficiency by leveraging the
    ability to spatially place multiple audio streams to provide timely
    auditory feedback.
  • Emacspeak 42.0 while moving to GitHub from Google Code continues to
    innovate in the areas of auditory user interfaces and efficient,
    light-weight Internet access.
  • Emacspeak 41.0 continues to improve
    on the desire to provide not just equal, but superior access —
    technology when correctly implemented can significantly enhance the
    human ability.
  • Emacspeak 40.0 goes back to Web basics by enabling
    efficient access to large amounts of readable Web content.
  • Emacspeak 39.0 continues the Emacspeak tradition of increasing the breadth of
    user tasks that are covered without introducing unnecessary
    bloatware.
  • Emacspeak 38.0 is the latest in a series of award-winning
    releases from Emacspeak Inc.
  • Emacspeak 37.0 continues the tradition of
    delivering robust software as reflected by its code-name.
  • Emacspeak 36.0 enhances the audio desktop with many new tools including full
    EPub support — hence the name EPubDog.
  • Emacspeak 35.0 is all about
    teaching a new dog old tricks — and is aptly code-named HeadDog in
    on of our new Press/Analyst contact. emacspeak-34.0 (AKA Bubbles)
    established a new beach-head with respect to rapid task completion in
    an eyes-free environment.
  • Emacspeak-33.0 AKA StarDog brings
    unparalleled cloud access to the audio desktop.
  • Emacspeak 32.0 AKA
    LuckyDog continues to innovate via open technologies for better
    access.
  • Emacspeak 31.0 AKA TweetDog — adds tweeting to the Emacspeak
    desktop.
  • Emacspeak 30.0 AKA SocialDog brings the Social Web to the
    audio desktop—you cant but be social if you speak!
  • Emacspeak 29.0—AKAAbleDog—is a testament to the resilliance and innovation
    embodied by Open Source software—it would not exist without the
    thriving Emacs community that continues to ensure that Emacs remains
    one of the premier user environments despite perhaps also being one of
    the oldest.
  • Emacspeak 28.0—AKA PuppyDog—exemplifies the rapid pace of
    development evinced by Open Source software.
  • Emacspeak 27.0—AKA
    FastDog—is the latest in a sequence of upgrades that make previous
    releases obsolete and downgrades unnecessary.
  • Emacspeak 26—AKA
    LeadDog—continues the tradition of introducing innovative access
    solutions that are unfettered by the constraints inherent in
    traditional adaptive technologies.
  • Emacspeak 25 —AKA ActiveDog
    —re-activates open, unfettered access to online
    information.
  • Emacspeak-Alive —AKA LiveDog —enlivens open, unfettered
    information access with a series of live updates that once again
    demonstrate the power and agility of open source software
    development.
  • Emacspeak 23.0 — AKA Retriever—went the extra mile in
    fetching full access.
  • Emacspeak 22.0 —AKA GuideDog —helps users
    navigate the Web more effectively than ever before.
  • Emacspeak 21.0
    —AKA PlayDog —continued the
    Emacspeak tradition of relying on enhanced
    productivity to liberate users.
  • Emacspeak-20.0 —AKA LeapDog —continues
    the long established GNU/Emacs tradition of integrated innovation to
    create a pleasurable computing environment for eyes-free
    interaction.
  • emacspeak-19.0 –AKA WorkDog– is designed to enhance
    user productivity at work and leisure.
  • Emacspeak-18.0 –code named
    GoodDog– continued the Emacspeak tradition of enhancing user
    productivity and thereby reducing total cost of
    ownership.
  • Emacspeak-17.0 –code named HappyDog– enhances user
    productivity by exploiting today's evolving WWW
    standards.
  • Emacspeak-16.0 –code named CleverDog– the follow-up to
    SmartDog– continued the tradition of working better, faster,
    smarter.
  • Emacspeak-15.0 –code named SmartDog–followed up on TopDog
    as the next in a continuing series of award-winning audio desktop
    releases from Emacspeak Inc.
  • Emacspeak-14.0 –code named TopDog–was

the first release of this millennium.

  • Emacspeak-13.0 –codenamed
    YellowLab– was the closing release of the
    20th. century.
  • Emacspeak-12.0 –code named GoldenDog– began
    leveraging the evolving semantic WWW to provide task-oriented speech
    access to Webformation.
  • Emacspeak-11.0 –code named Aster– went the
    final step in making Linux a zero-cost Internet access solution for
    blind and visually impaired users.
  • Emacspeak-10.0 –(AKA
    Emacspeak-2000) code named WonderDog– continued the tradition of
    award-winning software releases designed to make eyes-free computing a
    productive and pleasurable experience.
  • Emacspeak-9.0 –(AKA
    Emacspeak 99) code named BlackLab– continued to innovate in the areas
    of speech interaction and interactive accessibility.
  • Emacspeak-8.0 –(AKA Emacspeak-98++) code named BlackDog– was a major upgrade to
    the speech output extension to Emacs.
  • Emacspeak-95 (code named Illinois) was released as OpenSource on
    the Internet in May 1995 as the first complete speech interface
    to UNIX workstations. The subsequent release, Emacspeak-96 (code
    named Egypt) made available in May 1996 provided significant
    enhancements to the interface. Emacspeak-97 (Tennessee) went
    further in providing a true audio desktop. Emacspeak-98
    integrated Internetworking into all aspects of the audio desktop
    to provide the first fully interactive speech-enabled WebTop.

8 About Emacspeak:

Originally based at Cornell (NY) —
http://www.cs.cornell.edu/home/raman —home to Auditory User
Interfaces (AUI) on the WWW, Emacspeak is now maintained on GitHub
https://github.com/tvraman/emacspeak. The system is mirrored
world-wide by an international network of software archives and
bundled voluntarily with all major Linux distributions. On Monday,
April 12, 1999, Emacspeak became part of the Smithsonian's Permanent
Research Collection
on Information Technology at the Smithsonian's
National Museum of American History.


The Emacspeak mailing list is archived at Vassar –the home of the
Emacspeak mailing list– thanks to Greg Priest-Dorman, and provides a
valuable knowledge base for new users.


9 Press/Analyst Contact: Tilden Labrador

Going forward, Tilden acknowledges his exclusive monopoly on
setting the direction of the Emacspeak Audio Desktop, and
promises to exercise this freedom to innovate and her resulting
power responsibly (as before) in the interest of all dogs.


*About This Release:



Windows-Free (WF) is a favorite battle-cry of The League Against
Forced Fenestration (LAFF). –see
http://www.usdoj.gov/atr/cases/f3800/msjudgex.htm for details on
the ill-effects of Forced Fenestration.


CopyWrite )C( Aster, Hubbell and Tilden Labrador. All Writes Reserved.
HeadDog (DM), LiveDog (DM), GoldenDog (DM), BlackDog (DM) etc., are Registered
Dogmarks of Aster, Hubbell and Tilden Labrador. All other dogs belong to
their respective owners.

Monday, January 08, 2018

Updating Voxin TTS Server To Avoid A Possible ALSA Bug

Updating Voxin TTS Server To Avoid A Possible ALSA Bug

1 Summary

I recently updated to a new Linux laptop running the latest Debian
(Rodete). The upgrade went smoothly, but when I started using the
machine, I found that the Emacspeak TTS server for Voxin (Outloud)
crashed consistently; here, consistently equated to crashing on short
utterances which made typing or navigating by character an extremely
frustrating experience.


I fixed the issue by creating a work-around in the TTS server
atcleci.cpp::xrun
— if you run into this issue, make sure to update and rebuild
atcleci.so from GitHub; alternatively, you'll find an updated
atcleci.so in the servers/linux-outloud/lib/ directory after a
git update that you can copy over to your servers/linux-outloud
directory.


2 What Was Crashing

I use a DMIX plugin as the default device — and have many ALSA
virtual devices that are defined in terms of this device — see my
asoundrc. With this configuration, writing to the ALSA device was
raising an EPIPE error — normally this error indicates a buffer
underrun — that's when ALSA is starved of audio data. But in many
of these cases, the ALSA device was still in a RUNNING rather than
an XRUN state — this caused the Emacspeak server to
abort. Curiously, this happened only sporadically — and from my
experimentation only happened when there were multiple streams of
audio active on the machine.
A few Google searches showed threads on the alsa/kernel devel lists
that indicated that this bug was present in the case of DMIX devices
— it was hard to tell if the patch that was submitted on the
alsa-devel list had made it into my installation of Debian.


3 Fixing The Problem

My original implementation of function xrun had been cloned from
aplay.c about 15+ years ago — looking at the newest aplay
implementation, little to nothing had changed there. I finally worked
around the issue by adding a call to

snd_pcm_prepare(AHandle) 

whenever ALSA raised an EPIPE error during write — with the ALSA
device state in a RUNNING rather than an XRUN state. This
appears to fix the issue.