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fix: workaround a libstdc++ on random_device #208
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On fairly recent versions of libstdc++ the `std::random_device` class fails when used by multiple threads: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94087 We workaround this problem by detecting the version of the standard C++ library, and if it is `libstdc++` and it is a version after 20200128 then we use `rdrand` as the token value to initialize `std::random_device`, which does not have the problem with multiple threads.
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@@ Coverage Diff @@
## master #208 +/- ##
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+ Coverage 96.26% 96.28% +0.01%
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Files 97 97
Lines 4421 4443 +22
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+ Hits 4256 4278 +22
Misses 165 165
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This was referenced Apr 1, 2020
coryan
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Apr 1, 2020
The workaround put in place in googleapis#208 does not work with g++-9.3.1 on Fedora:31. Despite this being a "newer" version of libstdc++, it does not support `rdrand` as a token for `std::random_device` maybe because the CPU specific tokens are not enabled. For now, use `/dev/urandom` which seems to be supported on all Linux distros. On other platforms we continue to use the default constructor for `std::random_device`. It might be possible to refine this and detect, at run-time, if `rdrand` is supported, but that seems like an improvement that can wait a little bit.
coryan
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Apr 1, 2020
The workaround put in place in #208 does not work with g++-9.3.1 on Fedora:31. Despite this being a "newer" version of libstdc++, it does not support `rdrand` as a token for `std::random_device` maybe because the CPU specific tokens are not enabled. For now, use `/dev/urandom` which seems to be supported on all Linux distros. On other platforms we continue to use the default constructor for `std::random_device`. It might be possible to refine this and detect, at run-time, if `rdrand` is supported, but that seems like an improvement that can wait a little bit.
coryan
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Apr 24, 2020
…-cpp-common#208) On fairly recent versions of libstdc++ the `std::random_device` class fails when used by multiple threads: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94087 We workaround this problem by detecting the version of the standard C++ library, and if it is `libstdc++` and it is a version after 20200128 then we use `rdrand` as the token value to initialize `std::random_device`, which does not have the problem with multiple threads.
coryan
added a commit
to coryan/google-cloud-cpp
that referenced
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Apr 24, 2020
…-cloud-cpp-common#272) The workaround put in place in googleapis/google-cloud-cpp-common#208 does not work with g++-9.3.1 on Fedora:31. Despite this being a "newer" version of libstdc++, it does not support `rdrand` as a token for `std::random_device` maybe because the CPU specific tokens are not enabled. For now, use `/dev/urandom` which seems to be supported on all Linux distros. On other platforms we continue to use the default constructor for `std::random_device`. It might be possible to refine this and detect, at run-time, if `rdrand` is supported, but that seems like an improvement that can wait a little bit.
coryan
added a commit
to coryan/google-cloud-cpp
that referenced
this pull request
Apr 24, 2020
…-cpp-common#208) On fairly recent versions of libstdc++ the `std::random_device` class fails when used by multiple threads: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94087 We workaround this problem by detecting the version of the standard C++ library, and if it is `libstdc++` and it is a version after 20200128 then we use `rdrand` as the token value to initialize `std::random_device`, which does not have the problem with multiple threads.
coryan
added a commit
to coryan/google-cloud-cpp
that referenced
this pull request
Apr 24, 2020
…-cloud-cpp-common#272) The workaround put in place in googleapis/google-cloud-cpp-common#208 does not work with g++-9.3.1 on Fedora:31. Despite this being a "newer" version of libstdc++, it does not support `rdrand` as a token for `std::random_device` maybe because the CPU specific tokens are not enabled. For now, use `/dev/urandom` which seems to be supported on all Linux distros. On other platforms we continue to use the default constructor for `std::random_device`. It might be possible to refine this and detect, at run-time, if `rdrand` is supported, but that seems like an improvement that can wait a little bit.
coryan
added a commit
to coryan/google-cloud-cpp
that referenced
this pull request
Apr 24, 2020
…-cpp-common#208) On fairly recent versions of libstdc++ the `std::random_device` class fails when used by multiple threads: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94087 We workaround this problem by detecting the version of the standard C++ library, and if it is `libstdc++` and it is a version after 20200128 then we use `rdrand` as the token value to initialize `std::random_device`, which does not have the problem with multiple threads.
coryan
added a commit
to coryan/google-cloud-cpp
that referenced
this pull request
Apr 24, 2020
…-cloud-cpp-common#272) The workaround put in place in googleapis/google-cloud-cpp-common#208 does not work with g++-9.3.1 on Fedora:31. Despite this being a "newer" version of libstdc++, it does not support `rdrand` as a token for `std::random_device` maybe because the CPU specific tokens are not enabled. For now, use `/dev/urandom` which seems to be supported on all Linux distros. On other platforms we continue to use the default constructor for `std::random_device`. It might be possible to refine this and detect, at run-time, if `rdrand` is supported, but that seems like an improvement that can wait a little bit.
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On fairly recent versions of libstdc++ the
std::random_deviceclassfails when used by multiple threads:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94087
We workaround this problem by detecting the version of the standard C++
library, and if it is
libstdc++and it is a version after 20200128then we use
rdrandas the token value to initializestd::random_device, which does not have the problem with multiplethreads.
Part of the work for googleapis/google-cloud-cpp#3437
This change is