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da0a01367c
The non-blocking API has native (assembler) implementations for x86_64, i386, and (with recent patch) aarch64; these implementations are the most efficient. For other architectures, a fallback to ucontext is supported. But ucontext is not the most efficient, and it is not available on all platforms (it has been deprecated in POSIX). The boost::context library provides an alternative fallback that is available on more architectures and should be more efficient than ucontext (if still not quite as fast as the native support). This patch adds a CMake option -DWITH_BOOST_CONTEXT=ON that adds boost::context as a dependency of libmariadb to provide a fallback on non-natively supported architectures. Boost::context is preferred over ucontext when both are available. The option is off by default and must be explicitly enabled by the user. This avoids introducing a C++ dependency (including dependency on a C++ compiler and on libstdc++) unless explicitly requested by the user (libmariadb is otherwise C-only). Tested-by: Brad Smith <brad@comstyle.com> Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>
118 lines
2.7 KiB
C++
118 lines
2.7 KiB
C++
#include "ma_config.h"
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#include "mysql.h"
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#include "ma_context.h"
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#ifdef MY_CONTEXT_USE_BOOST_CONTEXT
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#include <boost/fiber/context.hpp>
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namespace ctx=boost::context;
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struct my_context_intern {
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ctx::fiber parent, coro;
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void *stack_top(const my_context *c) {
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return (unsigned char *)(c->stack) + c->stack_size;
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}
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/* A StackAlloc for ctx::fiber that reuses our stack. */
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struct my_stack_alloc {
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typedef ctx::stack_traits traits_type;
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my_context *c;
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my_stack_alloc(my_context *c_arg) : c(c_arg) { };
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ctx::stack_context allocate() {
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ctx::stack_context sctx;
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sctx.size= c->stack_size;
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sctx.sp= ((my_context_intern *)c->internal_context)->stack_top(c);
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#if defined(BOOST_USE_VALGRIND) && defined(HAVE_VALGRIND)
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sctx.valgrind_stack_id= c->valgrind_stack_id;
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#endif
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return sctx;
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}
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void deallocate(ctx::stack_context & sctx) {
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/* Empty, we will re-use the stack. */
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}
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};
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};
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extern "C"
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int
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my_context_spawn(struct my_context *c, void (*f)(void *), void *d)
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{
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my_context_intern *ci= (my_context_intern *)c->internal_context;
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ci->coro= ctx::fiber(std::allocator_arg, my_context_intern::my_stack_alloc(c),
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[c, f, d](ctx::fiber && parent) {
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my_context_intern *ci= (my_context_intern *)c->internal_context;
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ci->parent= std::move(parent);
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(*f)(d);
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c->active= 0;
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return std::move(ci->parent);
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});
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c->active= 1;
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ci->coro= std::move(ci->coro).resume();
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return c->active;
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}
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extern "C"
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int
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my_context_continue(struct my_context *c)
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{
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if (!c->active)
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return 0;
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my_context_intern *ci= (my_context_intern *)c->internal_context;
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ci->coro= std::move(ci->coro).resume();
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return c->active;
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}
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extern "C"
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int
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my_context_yield(struct my_context *c)
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{
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if (!c->active)
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return -1;
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my_context_intern *ci= (my_context_intern *)c->internal_context;
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ci->parent= std::move(ci->parent).resume();
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return 0;
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}
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extern "C"
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int
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my_context_init(struct my_context *c, size_t stack_size)
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{
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memset(c, 0, sizeof(*c));
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if (!(c->stack= malloc(stack_size)))
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return -1; /* Out of memory */
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if (!(c->internal_context= new my_context_intern))
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{
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free(c->stack);
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return -1;
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}
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c->stack_size= stack_size;
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#ifdef HAVE_VALGRIND
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c->valgrind_stack_id=
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VALGRIND_STACK_REGISTER(c->stack, ((unsigned char *)(c->stack))+stack_size);
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#endif
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return 0;
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}
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extern "C"
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void
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my_context_destroy(struct my_context *c)
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{
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delete (my_context_intern *)c->internal_context;
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if (c->stack)
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{
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#ifdef HAVE_VALGRIND
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VALGRIND_STACK_DEREGISTER(c->valgrind_stack_id);
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#endif
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free(c->stack);
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}
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}
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#endif /* MY_CONTEXT_USE_BOOST_CONTEXT */
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