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Merge #21064: refactor: use std::shared_mutex & remove Boost Thread

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060a2a64d4 ci: remove boost thread installation (fanquake)
06e1d7d81d build: don't build or use Boost Thread (fanquake)
7097add83c refactor: replace Boost shared_mutex with std shared_mutex in sigcache (fanquake)
8e55981ef8 refactor: replace Boost shared_mutex with std shared_mutex in cuckoocache tests (fanquake)

Pull request description:

  This replaces `boost::shared_mutex` and `boost::unique_lock` with [`std::shared_mutex`](https://en.cppreference.com/w/cpp/thread/shared_mutex) & [`std::unique_lock`](https://en.cppreference.com/w/cpp/thread/unique_lock).

  Even though [some concerns were raised](https://github.com/bitcoin/bitcoin/issues/16684#issuecomment-726214696) in #16684 with regard to `std::shared_mutex` being unsafe to use across some glibc versions, I still think this change is an improvement. As I mentioned in #21022, I also think trying to restrict standard library feature usage based on bugs in glibc is not only hard to do, but it's not currently clear exactly how we do that in practice (does it also extend to patching out use in our dependencies, should we be implementing more runtime checks for features we are using, when do we consider an affected glibc "old enough" not to worry about? etc). If you take a look through the [glibc bug tracker](https://sourceware.org/bugzilla/describecomponents.cgi?product=glibc) you'll no doubt find plenty of (active) bug reports for standard library code we already using. Obviously not to say we shouldn't try and avoid buggy code where possible.

  Two other points:

  [Cory mentioned in #21022](https://github.com/bitcoin/bitcoin/pull/21022#issuecomment-769274179):
  > It also seems reasonable to me to worry that boost hits the same underlying glibc bug, and we've just not happened to trigger the right conditions yet.

  Moving away from Boost to the standard library also removes the potential for differences related to Boosts configuration. Boost has multiple versions of `shared_mutex`, and what you end up using, and what it's backed by depends on:
  * The version of Boost.
  * The platform you're building for.
  * Which version of `BOOST_THREAD_VERSION` is defined: (2,3,4 or 5) default=2. (see [here](https://www.boost.org/doc/libs/1_70_0/doc/html/thread/build.html#thread.build.configuration) for some of the differences).
  * Is `BOOST_THREAD_V2_SHARED_MUTEX` defined? (not by default). If so, you might get the ["less performant, but more robust"](https://github.com/boostorg/thread/issues/230#issuecomment-475937761) version of `shared_mutex`.

  A lot of these factors are eliminated by our use of depends, but users will have varying configurations. It's also not inconceivable to think that a distro, or some package manager might start defining something like `BOOST_THREAD_VERSION=3`. Boost tried to change the default from 2 to 3 at one point.

  With this change, we no longer use Boost Thread, so this PR also removes it from depends, the build system, CI etc.

  Previous similar PRs were #19183 & #20922. The authors are included in the commits here.
  Also related to #21022 - pthread sanity checking.

ACKs for top commit:
  laanwj:
    Code review ACK 060a2a64d4
  vasild:
    ACK 060a2a64d4

Tree-SHA512: 572d14d8c9de20bc434511f20d3f431836393ff915b2fe9de5a47a02dca76805ad5c3fc4cceecb4cd43f3ba939a0508178c4e60e62abdbaaa6b3e8db20b75b03
This commit is contained in:
Wladimir J. van der Laan
2021-02-12 11:21:05 +01:00
parent 54b66a6e5f 060a2a64d4
commit 9996b1806a
15 changed files with 28 additions and 217 deletions
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187
build-aux/m4/ax_boost_thread.m4
View File

@@ -1,187 +0,0 @@
# ===========================================================================
# https://www.gnu.org/software/autoconf-archive/ax_boost_thread.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_BOOST_THREAD
#
# DESCRIPTION
#
# Test for Thread library from the Boost C++ libraries. The macro requires
# a preceding call to AX_BOOST_BASE. Further documentation is available at
# <http://randspringer.de/boost/index.html>.
#
# This macro calls:
#
# AC_SUBST(BOOST_THREAD_LIB)
#
# And sets:
#
# HAVE_BOOST_THREAD
#
# LICENSE
#
# Copyright (c) 2009 Thomas Porschberg <thomas@randspringer.de>
# Copyright (c) 2009 Michael Tindal
#
# Copying and distribution of this file, with or without modification, are
# permitted in any medium without royalty provided the copyright notice
# and this notice are preserved. This file is offered as-is, without any
# warranty.
#serial 33
AC_DEFUN([AX_BOOST_THREAD],
[
AC_ARG_WITH([boost-thread],
AS_HELP_STRING([--with-boost-thread@<:@=special-lib@:>@],
[use the Thread library from boost -
it is possible to specify a certain library for the linker
e.g. --with-boost-thread=boost_thread-gcc-mt ]),
[
if test "$withval" = "yes"; then
want_boost="yes"
ax_boost_user_thread_lib=""
else
want_boost="yes"
ax_boost_user_thread_lib="$withval"
fi
],
[want_boost="yes"]
)
if test "x$want_boost" = "xyes"; then
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([AC_CANONICAL_BUILD])
CPPFLAGS_SAVED="$CPPFLAGS"
CPPFLAGS="$CPPFLAGS $BOOST_CPPFLAGS"
export CPPFLAGS
LDFLAGS_SAVED="$LDFLAGS"
LDFLAGS="$LDFLAGS $BOOST_LDFLAGS"
export LDFLAGS
AC_CACHE_CHECK(whether the Boost::Thread library is available,
ax_cv_boost_thread,
[AC_LANG_PUSH([C++])
CXXFLAGS_SAVE=$CXXFLAGS
case "x$host_os" in
xsolaris )
CXXFLAGS="-pthreads $CXXFLAGS"
break;
;;
xmingw32 )
CXXFLAGS="-mthreads $CXXFLAGS"
break;
;;
*android* )
break;
;;
* )
CXXFLAGS="-pthread $CXXFLAGS"
break;
;;
esac
AC_COMPILE_IFELSE([
AC_LANG_PROGRAM(
[[@%:@include <boost/thread/thread.hpp>]],
[[boost::thread_group thrds;
return 0;]])],
ax_cv_boost_thread=yes, ax_cv_boost_thread=no)
CXXFLAGS=$CXXFLAGS_SAVE
AC_LANG_POP([C++])
])
if test "x$ax_cv_boost_thread" = "xyes"; then
case "x$host_os" in
xsolaris )
BOOST_CPPFLAGS="-pthreads $BOOST_CPPFLAGS"
break;
;;
xmingw32 )
BOOST_CPPFLAGS="-mthreads $BOOST_CPPFLAGS"
break;
;;
*android* )
break;
;;
* )
BOOST_CPPFLAGS="-pthread $BOOST_CPPFLAGS"
break;
;;
esac
AC_SUBST(BOOST_CPPFLAGS)
AC_DEFINE(HAVE_BOOST_THREAD,,
[define if the Boost::Thread library is available])
BOOSTLIBDIR=`echo $BOOST_LDFLAGS | sed -e 's/@<:@^\/@:>@*//'`
LDFLAGS_SAVE=$LDFLAGS
case "x$host_os" in
*bsd* )
LDFLAGS="-pthread $LDFLAGS"
break;
;;
esac
if test "x$ax_boost_user_thread_lib" = "x"; then
for libextension in `ls -r $BOOSTLIBDIR/libboost_thread* 2>/dev/null | sed 's,.*/lib,,' | sed 's,\..*,,'`; do
ax_lib=${libextension}
AC_CHECK_LIB($ax_lib, exit,
[link_thread="yes"; break],
[link_thread="no"])
done
if test "x$link_thread" != "xyes"; then
for libextension in `ls -r $BOOSTLIBDIR/boost_thread* 2>/dev/null | sed 's,.*/,,' | sed 's,\..*,,'`; do
ax_lib=${libextension}
AC_CHECK_LIB($ax_lib, exit,
[link_thread="yes"; break],
[link_thread="no"])
done
fi
else
for ax_lib in $ax_boost_user_thread_lib boost_thread-$ax_boost_user_thread_lib; do
AC_CHECK_LIB($ax_lib, exit,
[link_thread="yes"; break],
[link_thread="no"])
done
fi
if test "x$ax_lib" = "x"; then
AC_MSG_ERROR(Could not find a version of the Boost::Thread library!)
fi
if test "x$link_thread" = "xno"; then
AC_MSG_ERROR(Could not link against $ax_lib !)
else
BOOST_THREAD_LIB="-l$ax_lib"
case "x$host_os" in
*bsd* )
BOOST_LDFLAGS="-pthread $BOOST_LDFLAGS"
break;
;;
xsolaris )
BOOST_THREAD_LIB="$BOOST_THREAD_LIB -lpthread"
break;
;;
xmingw32 )
break;
;;
*android* )
break;
;;
* )
BOOST_THREAD_LIB="$BOOST_THREAD_LIB -lpthread"
break;
;;
esac
AC_SUBST(BOOST_THREAD_LIB)
fi
fi
CPPFLAGS="$CPPFLAGS_SAVED"
LDFLAGS="$LDFLAGS_SAVED"
fi
])