LibThread: Move CLock to LibThread::Lock

And adapt all the code that uses it.

Libraries/LibThread/BackgroundAction.cpp

@@ -1,9 +1,9 @@
 #include <LibThread/BackgroundAction.h>
 #include <LibThread/Thread.h>
-#include <LibCore/CLock.h>
+#include <LibThread/Lock.h>
 #include <AK/Queue.h>
 
-static CLockable<Queue<Function<void()>>>* s_all_actions;
+static LibThread::Lockable<Queue<Function<void()>>>* s_all_actions;
 static LibThread::Thread* s_background_thread;
 
 static int background_thread_func()
@@ -27,13 +27,13 @@ static int background_thread_func()
 
 static void init()
 {
-    s_all_actions = new CLockable<Queue<Function<void()>>>();
+    s_all_actions = new LibThread::Lockable<Queue<Function<void()>>>();
     s_background_thread = new LibThread::Thread(background_thread_func);
     s_background_thread->set_name("Background thread");
     s_background_thread->start();
 }
 
-CLockable<Queue<Function<void()>>>& LibThread::BackgroundActionBase::all_actions()
+LibThread::Lockable<Queue<Function<void()>>>& LibThread::BackgroundActionBase::all_actions()
 {
     if (s_all_actions == nullptr)
         init();

Libraries/LibThread/BackgroundAction.h

@@ -6,8 +6,8 @@
 #include <AK/Queue.h>
 #include <AK/RefCounted.h>
 #include <LibCore/CEventLoop.h>
-#include <LibCore/CLock.h>
 #include <LibCore/CObject.h>
+#include <LibThread/Lock.h>
 #include <LibThread/Thread.h>
 
 namespace LibThread {
@@ -22,7 +22,7 @@ class BackgroundActionBase {
 private:
     BackgroundActionBase() {}
 
-    static CLockable<Queue<Function<void()>>>& all_actions();
+    static Lockable<Queue<Function<void()>>>& all_actions();
     static Thread& background_thread();
 };
 

Libraries/LibThread/Lock.h

@@ -0,0 +1,133 @@
+#pragma once
+
+#ifdef __serenity__
+
+#include <AK/Assertions.h>
+#include <AK/Types.h>
+#include <unistd.h>
+
+#define memory_barrier() asm volatile("" :: \
+                                          : "memory")
+
+static inline u32 CAS(volatile u32* mem, u32 newval, u32 oldval)
+{
+    u32 ret;
+    asm volatile(
+        "cmpxchgl %2, %1"
+        : "=a"(ret), "+m"(*mem)
+        : "r"(newval), "0"(oldval)
+        : "cc", "memory");
+    return ret;
+}
+
+namespace LibThread {
+
+class Lock {
+public:
+    Lock() {}
+    ~Lock() {}
+
+    void lock();
+    void unlock();
+
+private:
+    volatile u32 m_lock { 0 };
+    u32 m_level { 0 };
+    int m_holder { -1 };
+};
+
+class Locker {
+public:
+    [[gnu::always_inline]] inline explicit Locker(Lock& l)
+        : m_lock(l)
+    {
+        lock();
+    }
+    [[gnu::always_inline]] inline ~Locker() { unlock(); }
+    [[gnu::always_inline]] inline void unlock() { m_lock.unlock(); }
+    [[gnu::always_inline]] inline void lock() { m_lock.lock(); }
+
+private:
+    Lock& m_lock;
+};
+
+[[gnu::always_inline]] inline void Lock::lock()
+{
+    int tid = gettid();
+    for (;;) {
+        if (CAS(&m_lock, 1, 0) == 0) {
+            if (m_holder == -1 || m_holder == tid) {
+                m_holder = tid;
+                ++m_level;
+                memory_barrier();
+                m_lock = 0;
+                return;
+            }
+            m_lock = 0;
+        }
+        donate(m_holder);
+    }
+}
+
+inline void Lock::unlock()
+{
+    for (;;) {
+        if (CAS(&m_lock, 1, 0) == 0) {
+            ASSERT(m_holder == gettid());
+            ASSERT(m_level);
+            --m_level;
+            if (m_level) {
+                memory_barrier();
+                m_lock = 0;
+                return;
+            }
+            m_holder = -1;
+            memory_barrier();
+            m_lock = 0;
+            return;
+        }
+        donate(m_holder);
+    }
+}
+
+#define LOCKER(lock) LibThread::Locker locker(lock)
+
+template<typename T>
+class Lockable {
+public:
+    Lockable() {}
+    Lockable(T&& resource)
+        : m_resource(move(resource))
+    {
+    }
+    Lock& lock() { return m_lock; }
+    T& resource() { return m_resource; }
+
+    T lock_and_copy()
+    {
+        LOCKER(m_lock);
+        return m_resource;
+    }
+
+private:
+    T m_resource;
+    Lock m_lock;
+};
+
+}
+
+#else
+
+namespace LibThread {
+
+class Lock {
+public:
+    Lock() { }
+    ~Lock() { }
+};
+
+}
+
+#define LOCKER(x)
+
+#endif