cosmopolitan/libc/intrin/once.h

#ifndef COSMOPOLITAN_LIBC_INTRIN_ONCE_H_
#define COSMOPOLITAN_LIBC_INTRIN_ONCE_H_
#include "libc/intrin/spinlock.h"

#define _once(x)                       \
  ({                                   \
    typeof(x) oncerc;                  \
    static bool once;                  \
    static typeof(oncerc) onceresult;  \
    _Alignas(64) static char oncelock; \
    _spinlock(&oncelock);              \
    if (once) {                        \
      oncerc = onceresult;             \
    } else {                           \
      oncerc = onceresult = x;         \
    }                                  \
    _spunlock(&oncelock);              \
    oncerc;                            \
  })

#endif /* COSMOPOLITAN_LIBC_INTRIN_ONCE_H_ */
Fix bugs and make improvements - Get clone() working on FreeBSD - Increase some Python build quotas - Add more atomic builtins to chibicc - Fix ASAN poisoning of alloca() memory - Make MODE= mandatory link path tinier - Improve the examples folder a little bit - Start working on some more resource limits - Make the linenoise auto-complete UI as good as GNU readline - Update compile.com, avoiding AVX codegen on non-AVX systems - Make sure empty path to syscalls like opendir raises ENOENT - Correctly polyfill ENOENT vs. ENOTDIR on the New Technology - Port bestline's paredit features to //third_party/linenoise - Remove workarounds for RHEL 5.0 bugs that were fixed in 5.1 2022-04-20 09:56:53 -07:00			`#ifndef COSMOPOLITAN_LIBC_INTRIN_ONCE_H_`
			`#define COSMOPOLITAN_LIBC_INTRIN_ONCE_H_`
			`#include "libc/intrin/spinlock.h"`

Write some lock contention tests 2022-06-16 09:06:09 -07:00			`#define _once(x) \`
			`({ \`
			`typeof(x) oncerc; \`
			`static bool once; \`
			`static typeof(oncerc) onceresult; \`
			`_Alignas(64) static char oncelock; \`
			`_spinlock(&oncelock); \`
			`if (once) { \`
			`oncerc = onceresult; \`
			`} else { \`
			`oncerc = onceresult = x; \`
			`} \`
			`_spunlock(&oncelock); \`
			`oncerc; \`
Fix bugs and make improvements - Get clone() working on FreeBSD - Increase some Python build quotas - Add more atomic builtins to chibicc - Fix ASAN poisoning of alloca() memory - Make MODE= mandatory link path tinier - Improve the examples folder a little bit - Start working on some more resource limits - Make the linenoise auto-complete UI as good as GNU readline - Update compile.com, avoiding AVX codegen on non-AVX systems - Make sure empty path to syscalls like opendir raises ENOENT - Correctly polyfill ENOENT vs. ENOTDIR on the New Technology - Port bestline's paredit features to //third_party/linenoise - Remove workarounds for RHEL 5.0 bugs that were fixed in 5.1 2022-04-20 09:56:53 -07:00			`})`

			`#endif /* COSMOPOLITAN_LIBC_INTRIN_ONCE_H_ */`