put rw_lock to a single header file

build/src.pro

@@ -18,7 +18,8 @@ HEADERS += \
     ../include/circ_elem_array.h \
     ../include/circ_queue.h \
     ../include/ipc.h \
-    ../include/def.h
+    ../include/def.h \
+    ../include/rw_lock.h
 
 SOURCES += \
     ../src/shm.cpp \

include/rw_lock.h

@@ -0,0 +1,44 @@
+#pragma once
+
+#include <atomic>
+#include <thread>
+
+namespace ipc {
+
+class rw_lock {
+    std::atomic_size_t lc_ { 0 };
+
+    enum : std::size_t {
+        w_flag = std::numeric_limits<std::size_t>::max()
+    };
+
+public:
+    void r_lock(void) {
+        while(1) {
+            std::size_t old = lc_.load(std::memory_order_acquire);
+            std::size_t unlocked = old + 1;
+            if (unlocked &&
+                lc_.compare_exchange_weak(old, unlocked, std::memory_order_acq_rel)) {
+                break;
+            }
+            std::this_thread::yield();
+        }
+    }
+
+    void r_unlock(void) {
+        lc_.fetch_sub(1, std::memory_order_release);
+    }
+
+    void w_lock(void) {
+        std::size_t expected = 0;
+        while (!lc_.compare_exchange_weak(expected, w_flag, std::memory_order_acq_rel)) {
+            std::this_thread::yield();
+        }
+    }
+
+    void w_unlock(void) {
+        lc_.store(0, std::memory_order_release);
+    }
+};
+
+} // namespace ipc

src/ipc.cpp

@@ -1,6 +1,4 @@
 #include <unordered_map>
-#include <atomic>
-#include <thread>
 #include <memory>
 #include <type_traits>
 #include <cstring>
@@ -10,6 +8,7 @@
 
 #include "ipc.h"
 #include "circ_queue.h"
+#include "rw_lock.h"
 
 namespace {
 
@@ -27,42 +26,7 @@ using queue_t = circ::queue<msg_t>;
 using guard_t = std::unique_ptr<std::remove_pointer_t<handle_t>, void(*)(handle_t)>;
 
 std::unordered_map<handle_t, queue_t> h2q__;
-
+rw_lock h2q_lc__;
-class rw_lock {
-    std::atomic_size_t lc_ { 0 };
-
-    enum : std::size_t {
-        w_flag = std::numeric_limits<std::size_t>::max()
-    };
-
-public:
-    void r_lock(void) {
-        do {
-            std::size_t old = lc_.load(std::memory_order_acquire);
-            std::size_t unlocked = old + 1;
-            if (unlocked &&
-                lc_.compare_exchange_weak(old, unlocked, std::memory_order_acq_rel)) {
-                break;
-            }
-            std::this_thread::yield();
-        } while(1);
-    }
-
-    void r_unlock(void) {
-        lc_.fetch_sub(1, std::memory_order_release);
-    }
-
-    void w_lock(void) {
-        std::size_t expected = 0;
-        while (!lc_.compare_exchange_weak(expected, w_flag, std::memory_order_acq_rel)) {
-            std::this_thread::yield();
-        }
-    }
-
-    void w_unlock(void) {
-        lc_.store(0, std::memory_order_release);
-    }
-} h2q_lc__;
 
 queue_t* queue_of(handle_t h) {
     if (h == nullptr) {