iOS only single-threaded? about log4cplus HOT 8 CLOSED

Ooops, somehow, I mentally switched from iOS that you are concerned about to Android. :)

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IIRC there were some linking issues with the threaded version observed by somebody in the bast. I have no way of testing this so I rely on reports. There is no reason in log4cplus itself why it should not support threading on iOS as far as I know. Feel free to experiment and try different setting. Please report back if you make it work with threading.

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Multi-threaded works perfectly on the device. But somehow only arm64 version depends on __tlv_bootstrap that is private API for Apple...

If I will turn single-threaded mode, then what features will be turned off? NDC?

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There is a section in README.md about iOS support. At its very end there is note that suggests to comment out these lines from ConfigureChecks.cmake:

set(LOG4CPLUS_HAVE_TLS_SUPPORT 1)
set(LOG4CPLUS_THREAD_LOCAL_VAR "__thread")

This will disable use of TLS based on __thread keyword in log4cplus and it should fall back to POSIX' pthread_setspecific(). This, I think, should solve your problem.

To answer your question, NDC should work in single threaded build as well. In that case the "TLS" data are just a global variable then.

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So...
Thanks for you hint regarding how to turn off TLS. I'm using Autotools build system version. So I came to commenting line in configure.ac:

#AX_TLS_SUPPORT

Apple review passed.

Now I think we need to make TLS switchable with some flag to cmake and to ./configure. What do you think?

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Now I think we need to make TLS switchable with some flag to cmake and to ./configure. What do you think?

Using switches is suboptimal, IMHO.

I instead of switches, I would rather enhance the AX_TLS_SUPPORT macro to automatically disable TLS support for either iOS or Android or both, if it is simply never going to work. But if there is a reliable way how to detect that it will work, I would rather enhance it in this respect.

...

Well, I did some searching and it seems Android simply does not support __thread, so it should be disabled in the CMake configuration for Android by default.

I have actually never heard of anyone using log4cplus on Android through the Autotools build system, so fixing that might be less important.

So, if you feel like it, please submit patches that change the defaults for Android. If you know and can test and patch iOS support then do not hesitate to change it as well.

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I see https://llvm.org/bugs/show_bug.cgi?id=19232, it suggests iOS simply does not support TLS and only POSIX API is supported.

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I think it may be closed after pull request merged

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