CMakeLists.txt

@@ -185,6 +185,7 @@ set(TILE_SRCS
     "tile/base/thread/rw_mutex.cc"
     "tile/base/thread/scoped_lock.cc"
     "tile/base/thread/spinlock.cc"
+    "tile/base/memory_barrier.cc"
     "tile/fiber/detail/fiber.cc"
     "tile/io/detail/eintr_safe.cc"
     "tile/io/native/acceptor.cc"

tile/base/memory_barrier.cc

@@ -0,0 +1,45 @@
+#include "tile/base/memory_barrier.h"
+
+#include <mutex>
+#include <sys/mman.h>
+
+#include "tile/base/logging.h"
+#include "tile/base/never_destroyed.h"
+
+namespace tile {
+namespace internal {
+namespace {
+void *
+CreateOneByteDummyPage()
+{
+    auto ptr = mmap(nullptr, 1, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    TILE_PCHECK(ptr, "Cannot create dummy page for asymmetric memory barrier.");
+    (void) mlock(ptr, 1);
+    return ptr;
+}
+
+void
+HomemadeMembarrier()
+{
+    static void *dummy_page = CreateOneByteDummyPage();
+    MemoryBarrier();
+    static NeverDestroyed<std::mutex> lock;
+    std::lock_guard<std::mutex> _(*lock);
+
+    TILE_PCHECK(mprotect(dummy_page, 1, PROT_READ | PROT_WRITE) == 0, "Cannot protect dummy page.");
+    *static_cast<char volatile *>(dummy_page) = 0;
+    TILE_PCHECK(mprotect(dummy_page, 1, PROT_READ) == 0);
+
+    MemoryBarrier();
+}
+
+}// namespace
+
+void
+AsymmetricBarrierHeavy()
+{
+    HomemadeMembarrier();
+}
+}// namespace internal
+
+}// namespace tile

tile/base/memory_barrier.h

@@ -0,0 +1,45 @@
+#ifndef DOWNLINK__3PARTY_TILE_TILE_BASE_MEMORY_BARRIER_H
+#define DOWNLINK__3PARTY_TILE_TILE_BASE_MEMORY_BARRIER_H
+
+#pragma once
+
+#include <atomic>
+
+namespace tile {
+namespace internal {
+inline void
+CompilerBarrier()
+{
+    std::atomic_signal_fence(std::memory_order_seq_cst);
+}
+
+inline void
+ReadBarrier()
+{
+    std::atomic_thread_fence(std::memory_order_seq_cst);
+}
+
+inline void
+WriteBarrier()
+{
+    std::atomic_thread_fence(std::memory_order_seq_cst);
+}
+
+inline void
+MemoryBarrier()
+{
+    std::atomic_thread_fence(std::memory_order_seq_cst);
+}
+
+inline void
+AsymmetricBarrierLight()
+{
+    CompilerBarrier();
+}
+
+void AsymmetricBarrierHeavy();
+
+}// namespace internal
+}// namespace tile
+
+#endif// DOWNLINK__3PARTY_TILE_TILE_BASE_MEMORY_BARRIER_H