Why my QT app crashes at the destructor of std::thread on Android 10 devices?

I did some research on why my QT app crashes at the destructor of std::thread on Android 10 devices at the user side with the following call stack:

#00 /apex/com.android.runtime/lib64/bionic/libc.so (abort+160)
#01 /system/lib64/libc++.so (abort_message+232)
#02 /system/lib64/libc++.so (demangling_terminate_handler()+44)
#03 /system/lib64/libc++.so (std::__terminate(void (*)())+12)
#04 /system/lib64/libc++.so (std::terminate()+52)
#05 /system/lib64/libc++.so (std::__1::thread::~thread()+20)
#06 /apex/com.android.runtime/lib64/bionic/libc.so (__cxa_finalize+212)
#07 /apex/com.android.runtime/lib64/bionic/libc.so (exit+24)
#08 /data/app/com.domain.myapp-Rs_sm5VrLR1Jj8QW6oYByA==/lib/arm64/libplugins_platforms_qtforandroid_arm64-v8a.so

and figured out that its likely because std::thread destructor is being invoked while the thread is still joinable at some point of the application execution (thanks to G. M. on stackoverflow.com).

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‘Timestamp for this request is outside of the recvWindow’ error in CCXT

If I use CCXT on my Windows machine I periodically get ‘Timestamp for this request is outside of the recvWindow’ error.

Exchange has the following options by default:

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Shrinking MySQL database

Calculating disk space usage per MySQL DB:

sudo du -h /var/lib/mysql/
932M    /var/lib/mysql/beauty
179M    /var/lib/mysql/slogpost
485M    /var/lib/mysql/omegauto
8.0K    /var/lib/mysql/test
676K    /var/lib/mysql/sys
22G     /var/lib/mysql/bot
79M     /var/lib/mysql/master
11M     /var/lib/mysql/mysql
176K    /var/lib/mysql/phpmyadmin
21M     /var/lib/mysql/shar
127M    /var/lib/mysql/mike
1.1M    /var/lib/mysql/performance_schema
79M     /var/lib/mysql/devnote
12M     /var/lib/mysql/mike1
48K     /var/lib/mysql/game
24G     /var/lib/mysql/
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C++ binary serialization speed is comparable with std::memmove

Measuring std::memmove speed

I wrote a simple test that outputs std::memmove speed to the console:

AWT_ATTRIBUTE(size_t, element_count, 1000000);

std::unique_ptr<uint8_t> p_src(new uint8_t[element_count]);
std::memset(p_src.get(), 25u, element_count);

std::unique_ptr<uint8_t> p_dst(new uint8_t[element_count]);

context.out << _T("std::memmove: ");

awl::StopWatch w;

std::memmove(p_dst.get(), p_src.get(), element_count);

ReportSpeed(context, w, element_count);

context.out << std::endl;

And the similar tests for std::memset and std::vector::insert.

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A funny example of C++ code that MS can compile :)

In the code below, static_assert operates on the addresses of local variables, but however MS compiles it and the assertion does not fail:

#include <tuple>
#include <string>
 
struct A
{
    int a;
    double b;
    std::string c;
};
 
void f()
{
    A a{ 1, 3.0, "abc" };
    constexpr auto t1 = std::tie(a.a, a.b, a.c);
    static_assert(&std::get<0>(t1) == &a.a);
}

Use the following command to compile this example:

cl /std:c++17 /EHsc a.cpp
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How I solved “This version of the application is not configured for billing through Google Play”

I created an unlockable product in Google Play, added billing permission to the manifest:

<uses-permission android:name="com.android.vending.BILLING"/>

and implemented billing in my application, but when I attempted to purchase the product first time I got error ‘This version of the application is not configured for billing through Google Play‘:

This version of the application is not configured for billing through Google Play
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Basic ideas of version tolerant serialization in C++

Consider the following scenario: there was structure A in an old version of a C++ application:

struct A
{
    double a;
    int b;
    std::string c;
};

An instance of A was serialized into a file in a binary format and after that the application was updated to a new version.

But in the new version of the application structure A was modified by adding fields d and e and deleting field a:

struct A
{
    int b;
    std::vector<int> d;
    bool e;
    std::string c;
};

and the new version of the application needs to deserialize an instance of its new structure A from the file containing old version of A.

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Packaging QT application into Android App Bundle (AAB)

In Qt Creator 4.11.0 on Projects page check “Build .aab”:

This will create .aab file.

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Setting up Oracle Database for development

To set up an Oracle Database for development I install the database in a docker container and then modify password policies in the default user profile as follows:

ALTER PROFILE DEFAULT LIMIT COMPOSITE_LIMIT UNLIMITED
  PASSWORD_LIFE_TIME UNLIMITED
  PASSWORD_REUSE_TIME UNLIMITED
  PASSWORD_REUSE_MAX UNLIMITED
  PASSWORD_VERIFY_FUNCTION NULL
  PASSWORD_LOCK_TIME UNLIMITED
  PASSWORD_GRACE_TIME UNLIMITED
  FAILED_LOGIN_ATTEMPTS UNLIMITED;

this prevents passwords from expiring and users from being locked.

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A simple C++ serialization framework

I implemented a simple C++ binary serialization framework that makes a structure or class serializable by adding a macro that usually takes one line of code as shown in the example below:

struct A
{
    bool x;
    int y;

    AWL_SERIALIZABLE(x, y)
};

There is also a macro that makes a structure or a class equatable:

AWL_MEMBERWISE_EQUATABLE(A)
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