[C++] Make some clean up methods thread safe

[BewareMyPower]

Fixes #11760

Motivation

BasicEndToEndTest.testLookupThrottling is flaky, from the logs of #11760 we can see the test crashed in ClientImpl::shutdown. The Connection closed log shows that ConnectionPool has been closed, so the problem is related to the close of three ExecutorServiceProviders of ClientImpl.

ExecutorServiceProvider::close is not thread safe because ExecutorServiceProvider::get might access the executors_ field in different threads and get uses a lock to guarantee thread-safety while close doesn't. In addition, some clean up methods including ClientImpl#shutdown and ExecutorService#close might be called twice or more, which is not necessary and has potential bugs.

Modifications

The main changes are:

• Add a lock to guarantee thread-safety of ExecutorServiceProvider::close.
• Use an atomic variable to make sure the logic in ExecutorService#close is called only once.
• Avoid ConnectionPool#getConnectionAsync being called after close method is closed. In this case, return a future that is completed with ResultAlreadyClosed.
• Add more debug logs.

In addition, this PR involves other changes. First, the master branch's source code cannot be compiled in my local env (macOS + Clang 12.0.0 + Boost 1.74), the error is:

/usr/local/include/boost/proto/expr.hpp:140:44: error: unknown warning group '-Wdeprecated-copy', ignored [-Werror,-Wunknown-warning-option]
            #pragma GCC diagnostic ignored "-Wdeprecated-copy"

I followed boostorg/proto#30 to fix this compilation error.

Another change is to fix the logs format, we can see the filename is always the same from logs in #11760. The reason is #11668 has changed logger() method from static to inline. It will make all C++'s translation units share the same and random chosen definition of logger(), but we need different definitions with different __FILE__ in different translation units. So this PR modified static back to inline and fix related compilation errors.

Verifying this change

• Make sure that the change passes the CI checks.

This change is a trivial rework / code cleanup without any test coverage.

[lhotari]

Good work @BewareMyPower