We already have global place for intialization:
lldb_private::Initialize ()
This is in lldb.cpp. Feel free to add a HostInfoBase::Initialize() to this
function. This will solve your problems.
Greg
On Aug 21, 2014, at 10:10 AM, Zachary Turner <ztur...@google.com> wrote:
>
> BTW, another problem with std::call_once is that, like thread-safe function
> local statics as well, any kind of thread synchronization is undesirable if
> it can be avoided.
>
>
> On Thu, Aug 21, 2014 at 10:09 AM, Zachary Turner <ztur...@google.com> wrote:
> std::call_once would solve the problem, but it's also going to be ugly
> putting that all over the place. Another potential solution is to do
> something like this:
>
> // HostInfoBase.h
> class HostInfoBase
> {
> public:
> static void Initialize();
>
> private:
> static HostInfoFields *m_fields;
> };
>
> // HostInfoBase.cpp
>
> struct HostInfoFields
> {
> uint32_t m_number_cpus;
> std::string m_lldb_shared_library_path;
> // etc
> };
>
> HostInfoFields *HostInfoBase::m_fields = nullptr;
>
> void HostInfoBase::Initialize()
> {
> m_fields = new HostInfoFields();
> }
>
> // lldb-main.cpp
> int main(int argc, char **argv)
> {
> HostInfo::Initialize();
> }
>
>
> Thoughts?
>
>
> On Thu, Aug 21, 2014 at 10:03 AM, Greg Clayton <gclay...@apple.com> wrote:
>
> > On Aug 20, 2014, at 2:36 PM, Zachary Turner <ztur...@google.com> wrote:
> >
> > As part of my moving code from Host to HostInfo, I moved some
> > function-local statics to global class-member statics. The reason for this
> > is that MSVC doesn't support thread-safe function local statics until
> > VS2014, which is still only in technology preview, whereas LLVM, clang, and
> > by extension LLDB support building as far back as VS2012.
> >
> > Greg submitted r216080 to convert these global statics back to
> > function-local statics, but this had a bug in it which broke things for all
> > platforms, so I reverted it in r216123. A simple fix would have just been
> > to address the bug, but my original transition from function-local statics
> > to global statics was intentional due to the fact that any use of them on a
> > non-primitive type is undefined behavior on MSVC.
> >
> > So, I want to see if people have a strong preference one way or the other.
> > If the issue is just silencing the compiler warning that clang gives about
> > global constructors, then we can do that in CMake and/or the Xcode project.
> > On the other hand, I understand that global static constructors increase
> > application startup times. Is this a concern for anyone? If so, I can try
> > to come up with a solution. I think if we try to keep the use of statics
> > to a minimum, and make sure that they are generally simple types (e.g
> > std::string, which simply does a malloc), then there should be no
> > noticeable performance impact on startup.
> >
> > Thoughts?
>
> For our build submissions here at Apple we need to keep the number of global
> constructors to a minimum. We need to apply for exceptions for each global
> constructor that is added to a shared library or framework. This is the main
> reason for the change I made. global constructors are fine for apps and they
> get to make that decision, but for shared libraries, they should be avoided
> if possible.
>
> I would suggest using std::once for any issues you run into:
>
> static std::once_flag g_once_flag;
> std::call_once(g_once_flag, [](){
> // Insert code here to run once in a thread safe way
> });
>
>
>
>
>
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