'Fresh Dressed" premieres on Monday, October 13 at 10P/9C.

It's nothing to be a 'black american' goddess!

Whoosh!

He says he was “beaten into submission” over it.

Warwick Workmen’s Club Two defeated Spanish Point Boat Club Two 3 – 1 to claim the Mike Zimmerman Team Challenge title. Captain Steven Bremar got Warwick off to a flying start when he defeated Point’s Billy Wotton sinking the pink ball to take the 1st game, 58 – 39. John Orr equalized for Spanish Point […]

[Updated] A yacht sailing from Bermuda was abandoned yesterday [May 18], and the crew were evacuated after striking a whale and sustaining damage to the hull. Skipper Joost Gehrels, doubted that the boat — called Outer Limits — could safety return to Bermuda and issued a MayDay to request immediate assistance. Bermuda Radio contacted vessels […]

Photographs recently captured in the Challenger Banks area offer a stark reminder of the perils that whales can face in the ocean, with the whale spotted harbouring a slash across its back that whale researcher Andrew Stevenson said appears to have been caused by the prop of a small boat, lopping off its dorsal fin. Mr Stevenson […]

Last night’s lightning storm appears to have damaged the Seventh-Day Adventist Church in Southampton, with the Church’s roof sustaining damage overnight. The Bermuda Fire & Rescue Service are presently on scene assessing the situation. Dr. Sydney Gibbons, the Church’s Pastor, confirmed that is no internal damage to the church and added that they are looking […]

‘Films at BUEI’ will screen the 2023 crime drama ‘The Bikeriders’ on September 28th. A spokesperson said, “‘Films at BUEI’ continues at the Bermuda Underwater Exploration Institute [BUEI] with the screening of the 2023 Crime/Drama, ‘The Bikeriders’ on Saturday, September 28th at 7:30pm in our Tradewinds Auditorium [Wheelchair Accessible]. “‘The Bikeriders’ is an American period […]

Apple previously confirmed that iOS 18.2 will be released in December, and now a potential release date within the month has surfaced.


We believe that Apple is likely planning to release iOS 18.2 on Monday, December 9, based on a recent notice that British carrier EE provided to its customers. In the notice, EE said it will be discontinuing an iPhone feature known as "Wi-Fi calling on other supported iCloud-connected devices" on December 9. The feature enables users to make Wi-Fi calls on devices like the iPad and Mac, even when their iPhone is not nearby.

The second developer beta of iOS 18.2 last week came bundled with a new EE carrier settings version numbered 60.5.2, up from 59.5.1 on the first iOS 18.2 beta and iOS 18.1. The new carrier settings version removed the "Add Wi-Fi Calling For Other Devices" toggle from the Wi-Fi Calling section in the Settings app on iPhones used by EE customers, in line with the carrier announcing that it will stop offering the feature next month.

Most carrier setting updates are bundled with iOS updates, aside from ones with bug fixes, so EE has likely indirectly revealed that iOS 18.2 will be released on December 9. We are not absolutely certain about this date, but it is a very likely possibility.

iOS 18.2 being released on December 9 would not be very surprising. Apple already said the update was coming next month, many iOS updates are released on Mondays, and the second half of the month is pretty much ruled out due to the holiday season. Nevertheless, you can now mark your calendars a little more precisely.

iOS 18.2 includes additional Apple Intelligence features for iPhone 15 Pro models and all iPhone 16 models, including Genmoji, Image Playground, ChatGPT integration for Siri, and more. On all compatible iPhones, the update also adds a new Defaults section in the Settings app, an item location sharing feature in the Find My app, and more.

(Thanks, Harvey!)

Apple has considered building its own line of smart home accessories, reports Bloomberg's Mark Gurman. Apple could manufacture smart home cameras and other devices that would connect to its HomeKit smart home platform and that would tie in with a planned smart home "command center" that could come out as soon as next year.


As one example, Gurman suggests Apple could create an indoor security camera that could also be used as a baby monitor, which is in line with a report we heard from Apple analyst Ming-Chi Kuo yesterday.

Kuo claimed that Apple is designing a smart home camera that will be manufactured starting in 2026, with Apple planning to sell "tens of millions" of the devices over the long term. Kuo says that the cameras that Apple is working on will have wireless connectivity and deep integration with Apple Intelligence and Siri.

Gurman does not seem as sure that Apple will follow through on plans to create its own smart home products. He says that it's something Apple is "exploring" that could be prioritized should its upcoming smart home hub device turn out to be a success.

Apple would likely emphasize privacy with its smart home cameras, providing an alternative to cameras from companies like Amazon's Ring and Google's Nest. Ring has been derided for its privacy policies over the years, primarily because it had a "Request for Assistance" tool that allowed law enforcement officials to request video footage from Ring customers. Ring has provided police officers with Ring camera footage without notifying users, and reserves the right to do so in emergency situations. Google's Nest brand also says that it will provide police with smart home camera footage in emergency situations without a warrant.

Apple is known for having strong privacy protections, and it is possible that customers would trust a smart home camera from Apple more than a smart home camera from a company like Ring. Apple already designed a ‌HomeKit‌ protocol for cameras called HomeKit Secure Video, which is end-to-end encrypted.

Prior to coming out with any smart home accessories, Apple plans to release an iPad-like smart home display that will serve as a home hub. The smart home device, which is set to come out as soon as March 2025, will run apps and will control ‌HomeKit‌ and Matter-based accessories.

The real threat is collusion. When journalists strike secret alliances with the very people they're supposed to be holding accountable, we are in deep trouble. Lies go unchallenged.  Democracy cannot function. And that's what we're watching right now. Continue reading →

The Small-Animallike Lady is Adored by the Ice Prince is a brand new romance manga from Yen Press. This first volume takes us to a familiar setting where there's a royal arranged marriage involved, and some frozen hearts are melted along the way!

UODATE: The bike sold, quickly, for the full asking price to the first person who showed up. Which was cool. And even better, the guy was like, "Who did the pictures? They jumped out at me."

(Tiny speedlights FTW...)



Have you tried to buy a new bike lately? Or even a used bike?

The coronavirus pandemic has made them very tough to find. Between homebound people snapping them up and all of the various broken supply chains, most of the bike inventory — other than very pricey specialty bikes — has pretty much vanished.

Which means that if you have a functional bike in your garage that you don't need, it will likely never be worth more than it is right now.

My daughter Emily has an unneeded bike in the garage. It's a Trek 7100, which is decent hybrid. She rode it to middle school. But she's just graduated college and won't be bringing it to her new job.

But right now it should fetch a nice price in the Craigslist Bicycle Hunger Games. Especially if it is photographed and presented well.

So that's exactly what we are going to do today: photograph a bike with a basic two speedlight kit.Read more »

1. NSW nurses strike heaps wage pressure on Minns government  The Australian Financial Review
2. Hundreds of elective surgeries cancelled as 10,000 nurses and midwives walk off job in NSW  ABC News
3. Nurses took to the streets after ‘insulting’ pay offer. Next stop, court  Sydney Morning Herald
4. Almost 700 surgeries cancelled as 12,000 NSW nurses strike for better pay  9News

Table of Contents

1. Thread Local storage exhausted
2. The layer of indirection
3. I can fix her
4. Let's write some tests!
5. Summary

Thread Local storage exhausted

In the last post I've described a technique to use dynamic variables by value instead of the name by utilizing the operator PROGV. Apparently it works fine on all Common Lisp implementations I've tried except from SBCL, where the number of thread local variables is by default limited to something below 4000. To add salt to the injury, these variables are not garbage collected.

Try the following code to crash into LDB:

(defun foo ()
  (loop for i from 0 below 4096 do
    (when (zerop (mod i 100))
      (print i))
    (progv (list (gensym)) (list 42)
      (values))))
(foo)

This renders our new technique not very practical given SBCL popularity. We need to either abandon the idea or come up with a workaround.

The layer of indirection

Luckily for us we've already introduced a layer of indirection. Operators to access dynamic variables are called DLET, DSET and DREF. This means, that it is enough to provide a kludge implementation for SBCL with minimal changes to the remaining code.

The old code works the same as previously except that instead of SYMBOL-VALUE we use the accessor DYNAMIC-VARIABLE-VALUE, and the old call to PROGV is now DYNAMIC-VARIABLE-PROGV. Moreover DYNAMIC-EFFECTIVE-SLOT used functions BOUNDP and MAKUNBOUND, so we replace these with DYNAMIC-VARIABLE-BOUND-P and DYNAMIC-VARIABLE-MAKUNBOUND. To abstract away things further we also introduce the constructor MAKE-DYNAMIC-VARIABLE

(defpackage "EU.TURTLEWARE.BLOG/DLET"
  (:local-nicknames ("MOP" #+closer-mop "C2MOP"
                           #+(and (not closer-mop) ecl) "MOP"
                           #+(and (not closer-mop) ccl) "CCL"
                           #+(and (not closer-mop) sbcl) "SB-MOP"))
  (:use "CL"))
(in-package "EU.TURTLEWARE.BLOG/DLET")

(eval-when (:compile-toplevel :execute :load-toplevel)
  (unless (member :bordeaux-threads *features*)
    (error "Please load BORDEAUX-THREADS."))
  (when (member :sbcl *features*)
    (unless (member :fake-progv-kludge *features*)
      (format t "~&;; Using FAKE-PROGV-KLUDGE for SBCL.~%")
      (push :fake-progv-kludge *features*))))

(defmacro dlet (bindings &body body)
  (flet ((pred (binding)
           (and (listp binding) (= 2 (length binding)))))
    (unless (every #'pred bindings)
      (error "DLET: bindings must be lists of two values.~%~
                Invalid bindings:~%~{ ~s~%~}" (remove-if #'pred bindings))))
  (loop for (var val) in bindings
        collect var into vars
        collect val into vals
        finally (return `(dynamic-variable-progv (list ,@vars) (list ,@vals)
                           ,@body))))

(defmacro dset (&rest pairs)
  `(setf ,@(loop for (var val) on pairs by #'cddr
                 collect `(dref ,var)
                 collect val)))

(defmacro dref (variable)
  `(dynamic-variable-value ,variable))

;;; ...

(defmethod mop:slot-boundp-using-class
    ((class standard-class)
     object
     (slotd dynamic-effective-slot))
  (dynamic-variable-bound-p (slot-dvar object slotd)))

(defmethod mop:slot-makunbound-using-class
    ((class standard-class)
     object
     (slotd dynamic-effective-slot))
  (dynamic-variable-makunbound (slot-dvar object slotd)))

With these in place we can change the portable implementation to conform.

#-fake-progv-kludge
(progn
  (defun make-dynamic-variable ()
    (gensym))

  (defun dynamic-variable-value (variable)
    (symbol-value variable))

  (defun (setf dynamic-variable-value) (value variable)
    (setf (symbol-value variable) value))

  (defun dynamic-variable-bound-p (variable)
    (boundp variable))

  (defun dynamic-variable-makunbound (variable)
    (makunbound variable))

  (defmacro dynamic-variable-progv (vars vals &body body)
    `(progv ,vars ,vals ,@body)))

I can fix her

The implementation for SBCL will mediate access to the dynamic variable value with a synchronized hash table with weak keys. The current process is the key of the hash table and the list of bindings is the value of the hash table. For compatibility between implementations the top level value of the symbol will be shared.

The variable +FAKE-UNBOUND+ is the marker that signifies, that the variable has no value. When the list of bindings is EQ to +CELL-UNBOUND+, then it means that we should use the global value. We add new bindings by pushing to it.

#+fake-progv-kludge
(progn
  (defvar +fake-unbound+ 'unbound)
  (defvar +cell-unbound+ '(no-binding))

  (defclass dynamic-variable ()
    ((tls-table
      :initform (make-hash-table :synchronized t :weakness :key)
      :reader dynamic-variable-tls-table)
     (top-value
      :initform +fake-unbound+
      :accessor dynamic-variable-top-value)))

  (defun make-dynamic-variable ()
    (make-instance 'dynamic-variable))

  (defun dynamic-variable-bindings (dvar)
    (let ((process (bt:current-thread))
          (tls-table (dynamic-variable-tls-table dvar)))
      (gethash process tls-table +cell-unbound+)))

  (defun (setf dynamic-variable-bindings) (value dvar)
    (let ((process (bt:current-thread))
          (tls-table (dynamic-variable-tls-table dvar)))
      (setf (gethash process tls-table +cell-unbound+) value))))

We define two readers for the variable value - one that simply reads the value, and the other that signals an error if the variable is unbound. Writer for its value either replaces the current binding, or if the value cell is unbound, then we modify the top-level symbol value. We use the value +FAKE-UNBOUND+ to check whether the variable is bound and to make it unbound.

#+fake-progv-kludge
(progn
  (defun %dynamic-variable-value (dvar)
    (let ((tls-binds (dynamic-variable-bindings dvar)))
      (if (eq tls-binds +cell-unbound+)
          (dynamic-variable-top-value dvar)
          (car tls-binds))))

  (defun dynamic-variable-value (dvar)
    (let ((tls-value (%dynamic-variable-value dvar)))
      (when (eq tls-value +fake-unbound+)
        (error 'unbound-variable :name "(unnamed)"))
      tls-value))

  (defun (setf dynamic-variable-value) (value dvar)
    (let ((tls-binds (dynamic-variable-bindings dvar)))
      (if (eq tls-binds +cell-unbound+)
          (setf (dynamic-variable-top-value dvar) value)
          (setf (car tls-binds) value))))

  (defun dynamic-variable-bound-p (dvar)
    (not (eq +fake-unbound+ (%dynamic-variable-value dvar))))

  (defun dynamic-variable-makunbound (dvar)
    (setf (dynamic-variable-value dvar) +fake-unbound+)))

Finally we define the operator to dynamically bind variables that behaves similar to PROGV. Note that we PUSH and POP from the thread-local hash table DYNAMIC-VARIABLE-BINDINGS, so no synchronization is necessary.

#+fake-progv-kludge
(defmacro dynamic-variable-progv (vars vals &body body)
  (let ((svars (gensym))
        (svals (gensym))
        (var (gensym))
        (val (gensym)))
    `(let ((,svars ,vars))
       (loop for ,svals = ,vals then (rest ,svals)
             for ,var in ,svars
             for ,val = (if ,svals (car ,svals) +fake-unbound+)
             do (push ,val (dynamic-variable-bindings ,var)))
       (unwind-protect (progn ,@body)
         (loop for ,var in ,svars
               do (pop (dynamic-variable-bindings ,var)))))))

Let's write some tests!

But of course, we are going to also write a test framework. It's short, I promise. As a bonus point the API is compatibile with fiveam, so it is possible to drop tests as is in the appropriate test suite.

(defvar *all-tests* '())

(defun run-tests ()
  (dolist (test (reverse *all-tests*))
    (format *debug-io* "Test ~a... " test)
    (handler-case (funcall test)
      (serious-condition (c)
        (format *debug-io* "Failed: ~a~%" c))
      (:no-error (&rest args)
        (declare (ignore args))
        (format *debug-io* "Passed.~%")))))

(defmacro test (name &body body)
  `(progn
     (pushnew ',name *all-tests*)
     (defun ,name () ,@body)))

(defmacro is (form)
  `(assert ,form))

(defmacro pass ())

(defmacro signals (condition form)
  `(is (block nil
         (handler-case ,form
           (,condition () (return t)))
         nil)))

(defmacro finishes (form)
  `(is (handler-case ,form
         (serious-condition (c)
           (declare (ignore c))
           nil)
         (:no-error (&rest args)
           (declare (ignore args))
           t))))

Now let's get to tests. First we'll test our metaclass:

(defclass dynamic-let.test-class ()
  ((slot1 :initarg :slot1 :dynamic nil :accessor slot1)
   (slot2 :initarg :slot2 :dynamic t   :accessor slot2)
   (slot3 :initarg :slot3              :accessor slot3))
  (:metaclass class-with-dynamic-slots))

(defparameter *dynamic-let.test-instance-1*
  (make-instance 'dynamic-let.test-class
                 :slot1 :a :slot2 :b :slot3 :c))

(defparameter *dynamic-let.test-instance-2*
  (make-instance 'dynamic-let.test-class
                 :slot1 :x :slot2 :y :slot3 :z))

(test dynamic-let.1
  (let ((o1 *dynamic-let.test-instance-1*)
        (o2 *dynamic-let.test-instance-2*))
    (with-slots (slot1 slot2 slot3) o1
      (is (eq :a slot1))
      (is (eq :b slot2))
      (is (eq :c slot3)))
    (with-slots (slot1 slot2 slot3) o2
      (is (eq :x slot1))
      (is (eq :y slot2))
      (is (eq :z slot3)))))

(test dynamic-let.2
  (let ((o1 *dynamic-let.test-instance-1*)
        (o2 *dynamic-let.test-instance-2*))
    (signals error (slot-dlet (((o1 'slot1) 1)) nil))
    (slot-dlet (((o1 'slot2) :k))
      (is (eq :k (slot-value o1 'slot2)))
      (is (eq :y (slot-value o2 'slot2))))))

(test dynamic-let.3
  (let ((o1 *dynamic-let.test-instance-1*)
        (exit nil)
        (fail nil))
    (flet ((make-runner (values)
             (lambda ()
               (slot-dlet (((o1 'slot2) :start))
                 (let ((value (slot2 o1)))
                   (unless (eq value :start)
                     (setf fail value)))
                 (loop until (eq exit t) do
                   (setf (slot2 o1) (elt values (random (length values))))
                   (let ((value (slot2 o1)))
                     (unless (member value values)
                       (setf fail value)
                       (setf exit t))))))))
      (let ((r1 (bt:make-thread (make-runner '(:k1 :k2))))
            (r2 (bt:make-thread (make-runner '(:k3 :k4))))
            (r3 (bt:make-thread (make-runner '(:k5 :k6)))))
        (sleep .1)
        (setf exit t)
        (map nil #'bt:join-thread (list r1 r2 r3))
        (is (eq (slot2 o1) :b))
        (is (null fail))))))

Then let's test the dynamic variable itself:

(test dynamic-let.4
  "Test basic dvar operators."
  (let ((dvar (make-dynamic-variable)))
    (is (eql 42 (dset dvar 42)))
    (is (eql 42 (dref dvar)))
    (ignore-errors
     (dlet ((dvar :x))
       (is (eql :x (dref dvar)))
       (error "foo")))
    (is (eql 42 (dref dvar)))))

(test dynamic-let.5
  "Test bound-p operator."
  (let ((dvar (make-dynamic-variable)))
    (is (not (dynamic-variable-bound-p dvar)))
    (dset dvar 15)
    (is (dynamic-variable-bound-p dvar))
    (dynamic-variable-makunbound dvar)
    (is (not (dynamic-variable-bound-p dvar)))))

(test dynamic-let.6
  "Test makunbound operator."
  (let ((dvar (make-dynamic-variable)))
    (dset dvar t)
    (is (dynamic-variable-bound-p dvar))
    (finishes (dynamic-variable-makunbound dvar))
    (is (not (dynamic-variable-bound-p dvar)))))

(test dynamic-let.7
  "Test locally bound-p operator."
  (let ((dvar (make-dynamic-variable)))
    (is (not (dynamic-variable-bound-p dvar)))
    (dlet ((dvar 15))
      (is (dynamic-variable-bound-p dvar)))
    (is (not (dynamic-variable-bound-p dvar)))))

(test dynamic-let.8
  "Test locally unbound-p operator."
  (let ((dvar (make-dynamic-variable)))
    (dset dvar t)
    (is (dynamic-variable-bound-p dvar))
    (dlet ((dvar nil))
      (is (dynamic-variable-bound-p dvar))
      (finishes (dynamic-variable-makunbound dvar))
      (is (not (dynamic-variable-bound-p dvar))))
    (is (dynamic-variable-bound-p dvar))))

(test dynamic-let.9
  "Stress test the implementation (see :FAKE-PROGV-KLUDGE)."
  (finishes                              ; at the same time
    (let ((dvars (loop repeat 4096 collect (make-dynamic-variable))))
      ;; ensure tls variable
      (loop for v in dvars do
        (dlet ((v 1))))
      (loop for i from 0 below 4096
            for r = (random 4096)
            for v1 in dvars
            for v2 = (elt dvars r) do
              (when (zerop (mod i 64))
                (pass))
              (dlet ((v1 42)
                     (v2 43))
                (values))))))

(test dynamic-let.0
  "Stress test the implementation (see :FAKE-PROGV-KLUDGE)."
  (finishes                             ; can be gc-ed
    (loop for i from 0 below 4096 do
      (when (zerop (mod i 64))
        (pass))
      (dlet (((make-dynamic-variable) 42))
        (values)))))

All that is left is to test both dynamic variable implementations:

BLOG/DLET> (lisp-implementation-type)
"ECL"
BLOG/DLET> (run-tests)
Test DYNAMIC-LET.1... Passed.
Test DYNAMIC-LET.2... Passed.
Test DYNAMIC-LET.3... Passed.
Test DYNAMIC-LET.4... Passed.
Test DYNAMIC-LET.5... Passed.
Test DYNAMIC-LET.6... Passed.
Test DYNAMIC-LET.7... Passed.
Test DYNAMIC-LET.8... Passed.
Test DYNAMIC-LET.9... Passed.
Test DYNAMIC-LET.0... Passed.
NIL

And with the kludge:

BLOG/DLET> (lisp-implementation-type)
"SBCL"
BLOG/DLET> (run-tests)
Test DYNAMIC-LET.1... Passed.
Test DYNAMIC-LET.2... Passed.
Test DYNAMIC-LET.3... Passed.
Test DYNAMIC-LET.4... Passed.
Test DYNAMIC-LET.5... Passed.
Test DYNAMIC-LET.6... Passed.
Test DYNAMIC-LET.7... Passed.
Test DYNAMIC-LET.8... Passed.
Test DYNAMIC-LET.9... Passed.
Test DYNAMIC-LET.0... Passed.
NIL

Summary

In this post we've made our implementation to work on SBCL even when there are more than a few thousand dynamic variables. We've also added a simple test suite that checks the basic behavior.

As it often happens, after achieving some goal we get greedy and achieve more. That's the case here as well. In the next (and the last) post in this series I'll explore the idea of adding truly thread-local variables without a shared global value. This will be useful for lazily creating context on threads that are outside of our control. We'll also generalize the implementation so it is possible to subclass and implement ones own flavor of a dynamic variable.

1. Why Virat Kohli, Jasprit Bumrah were missing from Perth nets; India ramp up privacy amid Manchester United-like security  Hindustan Times
2. Virat Kohli in focus: Intense net session begins for upcoming Test series against Australia  The Times of India
3. Virat Kohli in Australia for BGT: A timeline  India Today
4. Black veil of secrecy: India begin training in privacy in Perth  ESPNcricinfo
5. India to play intra-squad warm-up match at WACA on Friday ahead of Australia Tests but BCCI denies public viewing  Hindustan Times