// Points to the implicit sequence introduced by a living InSequence
// object (if any) in the current thread or NULL.
GTEST_API_ extern ThreadLocal<Sequence*> g_gmock_implicit_sequence;
这个类型的全局变量，会在get方法里申请heap的内存，以便自己使用，然后将这个内存地址放到thread local的变量。而且是一个全局变量，如果想在运行测试用例的时候加快运行，可以事调用get，提前申请内存。需要注意这个使用规则。
这个名称有些让人联系不上它的类型，所以下面的调用栈，初看的时候有些困扰。看gmock/gtest的时候需要注意。
google这个网站也是不能访问。
T* GetOrCreateValue() const {
ThreadLocalValueHolderBase* const holder =
static_cast<ThreadLocalValueHolderBase*>(pthread_getspecific(key_));
if (holder != nullptr) {
return CheckedDowncastToActualType<ValueHolder>(holder)->pointer();
}
ValueHolder* const new_holder = default_factory_->MakeNewHolder(); /// 在这里申请，调用到libgmock里的函数
ThreadLocalValueHolderBase* const holder_base = new_holder;
GTEST_CHECK_POSIX_SUCCESS_(pthread_setspecific(key_, holder_base));
return new_holder->pointer();
}
(gdb) bt
#0 0x00007ffff7bbd0a0 in testing::internal::ThreadLocal<testing::Sequence*>::DefaultValueHolderFactory::MakeNewHolder() const ()
from /home/charleyc/sbc/obj/linux_x86-64/3rd/lib64/libgmock.so
#1 0x000000001020c11a in testing::internal::ThreadLocal<testing::Sequence*>::GetOrCreateValue (
this=0x15561260 <testing::internal::g_gmock_implicit_sequence>) at ../obj/linux_x86-64/3rd/include/gtest/internal/gtest-port.h:2213
#2 0x000000001020c1a5 in testing::internal::ThreadLocal<testing::Sequence*>::pointer (this=<optimized out>) at ../obj/linux_x86-64/3rd/include/gtest/internal/gtest-port.h:2186
#3 0x000000001020c1b5 in testing::internal::ThreadLocal<testing::Sequence*>::get (this=<optimized out>)
at ../obj/linux_x86-64/3rd/include/gtest/internal/gtest-port.h:2187
#4 0x000000001219198f in testing::internal::FunctionMockerBase<void (cpICR*, AF_DiamAvpSubscriptionId&)>::AddNewExpectation
(char const*, int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::tuple<testing::Matcher<cpICR*>, testing::Matcher<AF_DiamAvpSubscriptionId&> > const&)
(this=0x7fffb3f17e88, file=file@entry=0x13275810 "/hom.cpp", line=line@entry=3964, source_text="EXPECT_CALL(*gmock_gld(_,_))", m=std::tuple containing = {
...}) at ../obj/linux_x86-64/3rd/include/gmock/gmock-spec-builders.h:1619
(gdb) disass
Dump of assembler code for function testing::internal::FunctionMockerBase<void (cpICR*, AF_DiamAvpSubscriptionId&)>::AddNewExpectation(char const*, int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::tuple<testing::Matcher<cpICR*>, testing::Matcher<AF_DiamAvpSubscriptionId&> > const&):
0x0000000012191910 <+0>: push %rbp
0x0000000012191911 <+1>: mov %rsp,%rbp
0x0000000012191914 <+4>: push %r15
0x0000000012191916 <+6>: mov %rcx,%r15
0x0000000012191919 <+9>: push %r14
0x000000001219191b <+11>: mov %edx,%r14d
0x000000001219191e <+14>: push %r13
0x0000000012191920 <+16>: mov %rsi,%r13
0x0000000012191923 <+19>: push %r12
0x0000000012191925 <+21>: push %rbx
0x0000000012191926 <+22>: mov %rdi,%rbx
0x0000000012191929 <+25>: sub $0x38,%rsp
0x000000001219192d <+29>: mov %r8,-0x58(%rbp)
testing::internal::UntypedFunctionMockerBase::MockObject() const
0x0000000012191931 <+33>: callq 0x1555dc90 <_ZNK7testing8internal25UntypedFunctionMockerBase10MockObjectEv@plt>
0x0000000012191936 <+38>: mov %r14d,%edx
0x0000000012191939 <+41>: mov %r13,%rsi
0x000000001219193c <+44>: mov %rax,%rdi
0x000000001219193f <+47>: callq 0x1555ef70 <_ZN7testing4Mock31RegisterUseByOnCallOrExpectCallEPKvPKci@plt>
0x0000000012191944 <+52>: mov $0x168,%edi
0x0000000012191949 <+57>: callq 0x12a2ebd0 <operator new(unsigned long)>
0x000000001219194e <+62>: mov -0x58(%rbp),%r8
0x0000000012191952 <+66>: mov %r14d,%ecx
0x0000000012191955 <+69>: mov %r13,%rdx
0x0000000012191958 <+72>: mov %rbx,%rsi
0x000000001219195b <+75>: mov %rax,%rdi
0x000000001219195e <+78>: mov %rax,%r12
0x0000000012191961 <+81>: mov %r8,%r9
0x0000000012191964 <+84>: mov %r15,%r8
0x0000000012191967 <+87>: callq 0x1218aaf0 <testing::internal::TypedExpectation<void (cpICR*, AF_DiamAvpSubscriptionId&)>::TypedExpectation(testing::internal::FunctionMockerBase<void (cpICR*, AF_DiamAvpSubscriptionId&)>*, char const*, int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::tuple<testing::Matcher<cpICR*>, testing::Matcher<AF_DiamAvpSubscriptionId&> > const&)>
0x000000001219196c <+92>: mov %r12,%rsi
0x000000001219196f <+95>: lea -0x50(%rbp),%rdi
0x0000000012191973 <+99>: callq 0x101ffec0 <testing::internal::linked_ptr<testing::internal::ExpectationBase>::linked_ptr(testing::internal::ExpectationBase*)>
0x0000000012191978 <+104>: lea 0x30(%rbx),%rdi
0x000000001219197c <+108>: lea -0x50(%rbp),%rsi
0x0000000012191980 <+112>: callq 0x10210c80 <std::vector<testing::internal::linked_ptr<testing::internal::ExpectationBase>, std::allocator<testing::internal::linked_ptr<testing::internal::ExpectationBase> > >::push_back(testing::internal::linked_ptr<testing::internal::ExpectationBase> const&)>
0x0000000012191985 <+117>: mov $0x15561260,%edi
0x000000001219198a <+122>: callq 0x1020c1b0 <testing::internal::ThreadLocal<testing::Sequence*>::get() const>
这个一个开源项目用的c++，那叫一个复杂。做个比喻，不知合不合适。说美国当年登月，后来过了多半个世纪，后来者还没居上，美国自己都被甩后边，没再重拾月球计划。