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dummzeuch

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dummzeuch last won the day on December 28 2020

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  • Delphi-Version
    Delphi 2007

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  1. dummzeuch

    Google Authenticator

    Google Authenticator is a One Time Password Generator. There are several alternatives that work the same way and are open source, e.g. FreeOTP is the one I use. These apps use the current time and a shared secret (with the server) to generate a 6 digit number. They all generate the same number given the same input, so you could use it to authenticate with your own app. The number is only valid for login for about 30 seconds. Of course Google Authenticator could use the data you add into it and the information about when you use it to log into which service for Googles purposes. But since it does not need an internet connection to fulfill its purpose, you could simply check whether it phones home or not. If it does, it's doing something it doesn't need to do and probably shouldn't do. Or, if you want to be 100% sure, use an open source solution and compile it yourself. (There are other methods to generate One Time Passwords, see e.g. Wikipedia for that.)
  2. I offered to help out and even submitted pull requests with updates for them, but they were ignored for several months. Then I gave up.
  3. If I remember correctly, it was added in Delphi 10.4, so it won't help much if you develop for multiple Delphi versions.
  4. dummzeuch

    spinlock primitives

    re 1: Then I probably need to repeat these tests on a system where the Delphi IDE hasn't run (yet), because I am not sure whether it had been running before the tests or not. re 2/3: There are lots of discussions on the web about Sleep(0) vs. Sleep(1) vs. SwitchToThread and there seems to be no definite answer which one to use in a spin lock. It all depends on the circumstances. re 4: Again, this depends on the circumstances. With a small protected section and low contention a spin lock might be way faster than a critical section. I was trying to find out whether that might solve some issues I had with a particular program. It turned out that it didn't (but again, I need to repeat the test taking into account what I have learned in the meantime), but this had started me into the topic.
  5. dummzeuch

    spinlock primitives

    Hm, shouldn't the assertion go into a constructor?
  6. dummzeuch

    spinlock primitives

    I read somewhere (when I was searching for 'Yield'), that Yield doesn't exist on Arm processors and there simply translates to NOP. Not sure whether I understood that correctly because at the time I wasn't really interested in Arm.
  7. dummzeuch

    spinlock primitives

    Yeah, right. Think again, Thomas. I did some tests and it turned out that in these tests(!) on my computer(!) Sleep(1) increased the throughput by more than 50% over Sleep(0), even though all threads were running in the same application and with the same priority: Sleep(0) 5 Writers 5 Readers Run1: Writes: 5738 Reads: 4683 [avg. per ms] Run2: Writes: 5662 Reads: 4716 [avg. per ms] Sleep(1) 5 Writers 5 Readers Run1: Writes: 10444 Reads: 7528 [avg. per ms] Run2: Writes: 8587 Reads: 9411 [avg. per ms] Note that it is quite possible that I bungled the tests. They are not as consistent as I would have expected.
  8. Actually I did less than a year ago: Compiling TeeChart 2020 for Delphi 2007 It won't help, of course.
  9. Unfortunately many well known commercial and open source libraries don't adhere to these. It's a major pain in the lower back every time I want to install Delphi on a new computer (which happens quite regularly, at least several times per year).
  10. dummzeuch

    spinlock primitives

    ... or simply assume a multi core system. When was the last time you saw a single core (Windows-) system in the wild? OK, a program could be restricted to a single core by the user or the OS, so there is that. And there are VMs which can also be configured to run on a single core even on a multi core system.
  11. dummzeuch

    spinlock primitives

    I'm writing my own spinlock to get a feel for what can be done. One of my programs shows some odd behavior when using a critical section so I tried to see whether this changes when switching to a spin lock. It seemed to work at first, but my last test failed miserably so I'm "going home" now. Quite possible, but since these require API calls, they have a significant overhead in the best case (no spinning required). I knew about Sleep(0) vs. Sleep(1), but wasn't that supposed to be changed in Windows Vista and later? (reading the second link) OK, apparently not. But since the threads in question are running with the same priority, Sleep(0) should work fine. Apart from that: the above code was just an example, how to prevent running a single CPU system at 100%.
  12. dummzeuch

    spinlock primitives

    You mean instead of Sleep()? I haven't thought much about that case yet. Using doTryLock it with sleep which gives a much higher throughput than doLock or a Critical Section in my tests on my computer. But I am not yet sure whether this makes any difference in a real world scenario. Apparently there the is the Pause instruction on Intel CPUs: https://stackoverflow.com/questions/4725676/how-does-x86-pause-instruction-work-in-spinlock-and-can-it-be-used-in-other-sc I'll have to look into it.
  13. dummzeuch

    spinlock primitives

    Yes, thats how a SpinLock is supposed to work, isn't it? That's why I added the doTryLock function which could be used like this: while not doTryLock(Lck) do Sleep(0);
  14. I am reinventing the wheel again (yes, I like doing that). Can you see anything wrong with these SpinLock functions? (for Win32 only) ///<summary> /// simple spin lock function, Lk must have been initialized with 0 before first use </summary> procedure doLock(var _Lk: Integer); asm mov edx, eax mov ecx, 1 @Loop: mov eax, 0 lock cmpxchg dword ptr [edx], ecx jnz @Loop end; ///<summary> /// simple spin unlock function, Lk must have been initialized with 0 before first use </summary> procedure doUnLock(var _Lk: Integer); asm lock dec dword ptr[eax]; end; ///<summary> /// simple spin trylock function, Lk must have been initialized with 0 before first use /// @returns True if the lock could be acquired, False otherwise </summary> function doTryLock(var _Lk: Integer): Boolean; asm mov edx, eax mov ecx, 1 mov eax, 0 lock cmpxchg dword ptr [edx], ecx setz al end; doLock and doUnlock are taken from https://vitaliburkov.wordpress.com/2011/10/28/parallel-programming-with-delphi-part-ii-resolving-race-conditions/ doTryLock is based on doLock and uses the setz opcode to return a boolean rather than looping. I have done tests and they seem to work, but it's always difficult to actually test multi threaded code.
  15. dummzeuch

    GExperts 1.3.18 experimental twm 2021-02-21 released

    Does anybody else have this compile error?
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