t3 | Create ThreeJS demos with little code | Frontend Framework library

The way that you have implemented the infinite recursive loop is a bit sketchy. It should be quite difficult to maintain it. My suggestion is to remove the dependencies/interactions between the asynchronous methods, and delegate the responsibility of calling them in a looping fashion to a "master" asynchronous method, that invokes them sequentially in a while loop:

I couldn't figure out your math. I think you should try annotating this kind of code with explanatory comments. Often that will help you spot your own mistake:

Here is a function that formats each element of the list of data frames. With R scoping rules what they are, notice format_tbls returns a workbook object, which allows the updates that occur inside the function to be passed to the object that is eventually saved to a file.

Note: I attempted to follow the formatting shown in the original question, but I have excluded the 'Na_string' addStyle call. This probably was intended to highlight NA's in the data.frames. The current code does not do that.

You could do something like this via tidyverse.

It seems you violate standad:

33.5.3 Class condition_variable [thread.condition.condvar]

void wait(unique_lock& lock);

Requires: lock.owns_lock() is true and lock.mutex() is locked by the calling thread, and either

(9.1) — no other thread is waiting on this condition_variable object or

(9.2) — lock.mutex() returns the same value for each of the lock arguments supplied by all concurrently waiting (via wait, wait_for, or wait_until) threads.

Cleary two threads are waiting and lock.mutex() does not return same.

Maybe what you are looking for is ntuple ?

array_column function returns a new array of values representing a single column from the input array and you are passing two arrays created with this function to the array_multisort which applies the changes to the arrays passed as params but you don't have pointers to those 2 arrays that have been sorted. That is to say that the array_multisort function is sorting array_column(...) and (array_column(...) not the $arr. The following can solve your problem:

One workaround to this error is to use an update join:

TL;DR: unfortunate combination of backward compatibility and ABI compatibility issues makes std::mutex bad until the next ABI break. OTOH, std::shared_mutex is good.

A decent implementation of std::mutex would try to use an atomic operation to acquire the lock, if busy, possibly would try spinning in a read loop (with some pause on x86), and ultimately will resort to OS wait.

There are a couple of ways to implement such std::mutex:

1. Directly delegate to corresponding OS APIs that do all of above.
2. Do spinning and atomic thing on its own, call OS APIs only for OS wait.

Sure, the first way is easier to implement, more friendly to debug, more robust. So it appears to be the way to go. The candidate APIs are:

• CRITICAL_SECTION APIs. A recursive mutex, that is lacking static initializer and needs explicit destruction
• SRWLOCK. A non-recursive shared mutex that has static initializer and doesn't need explicit destruction
• WaitOnAddress. An API to wait on particular variable to be changed, similar to Linux futex.

These primitives have OS version requirements:

• CRITICAL_SECTION existed since I think Windows 95, though TryEnterCriticalSection was not present in Windows 9x, but the ability to use CRITICAL_SECTION with CONDITION_VARIABLE was added since Windows Vista, with CONDITION_VARIABLE itself.
• SRWLOCK exists since Windows Vista, but TryAcquireSRWLockExclusive exists since Windows 7, so it can only directly implement std::mutex starting in Windows 7.
• WaitOnAddress was added since Windows 8.

By the time when std::mutex was added, Windows XP support by Visual Studio C++ library was needed, so it was implemented using doing things on its own. In fact, std::mutex and other sync stuff was delegated to ConCRT (Concurrency Runtime)

For Visual Studio 2015, the implementation was switched to use the best available mechanism, that is SRWLOCK starting in Windows 7, and CRITICAL_SECTION stating in Windows Vista. ConCRT turned out to be not the best mechanism, but it still was used for Windows XP and 2003. The polymorphism was implemented by making placement new of classes with virtual functions into a buffer provided by std::mutex and other primitives.

Note that this implementation breaks the requirement for std::mutex to be constexpr, because of runtime detection, placement new, and inability of pre-Window 7 implementation to have only static initializer.

As time passed support of Windows XP was finally dropped in VS 2019, and support of Windows Vista was dropped in VS 2022, the change is made to avoid ConCRT usage, the change is planned to avoid even runtime detection of SRWLOCK (disclosure: I've contributed these PRs). Still due to ABI compatibility for VS 2015 though VS 2022 it is not possible to simplify std::mutex implementation to avoid all this putting classes with virtual functions.

What is more sad, though SRWLOCK has static initializer, the said compatibility prevents from having constexpr mutex: we have to placement new the implementation there. It is not possible to avoid placement new, and make an implementation to construct right inside std::mutex, because std::mutex has to be standard layout class (see Why is std::mutex a standard-layout class?).

So the size overhead comes from the size of ConCRT mutex.

And the runtime overhead comes from the chain of call:

• library function call to get to the standard library implementation
• virtual function call to get to SRWLOCK-based implementation
• finally Windows API call.

Virtual function call is more expensive than usually due to standard library DLLs being built with /guard:cf.

Some part of the runtime overhead is due to std::mutex fills in ownership count and locked thread. Even though this information is not required for SRWLOCK. It is due to shared internal structure with recursive_mutex. The extra information may be helpful for debugging, but it does take time to fill it in.

std::shared_mutex was designed to support only systems starting Windows 7. So it uses SRWLOCK directly.

The size of std::shared_mutex is the size of SRWLOCK. SRWLOCK has the same size as a pointer (though internally it is not a pointer).

It still involves some avoidable overhead: it calls C++ runtime library, just to call Windows API, instead of calling Windows API directly. This looks fixable with the next ABI, though.

std::shared_mutex constructor could be constexpr, as SRWLOCK does not need dynamic initializer, but the standard prohibits voluntary adding constexpr to the standard classes.