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https://github.com/RGBCube/serenity
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LibThread: Move CLock to LibThread::Lock
And adapt all the code that uses it.
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parent
0826cc5a35
commit
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7 changed files with 42 additions and 34 deletions
133
Libraries/LibThread/Lock.h
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133
Libraries/LibThread/Lock.h
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#pragma once
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#ifdef __serenity__
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#include <AK/Assertions.h>
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#include <AK/Types.h>
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#include <unistd.h>
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#define memory_barrier() asm volatile("" :: \
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: "memory")
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static inline u32 CAS(volatile u32* mem, u32 newval, u32 oldval)
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{
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u32 ret;
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asm volatile(
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"cmpxchgl %2, %1"
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: "=a"(ret), "+m"(*mem)
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: "r"(newval), "0"(oldval)
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: "cc", "memory");
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return ret;
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}
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namespace LibThread {
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class Lock {
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public:
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Lock() {}
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~Lock() {}
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void lock();
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void unlock();
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private:
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volatile u32 m_lock { 0 };
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u32 m_level { 0 };
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int m_holder { -1 };
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};
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class Locker {
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public:
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[[gnu::always_inline]] inline explicit Locker(Lock& l)
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: m_lock(l)
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{
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lock();
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}
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[[gnu::always_inline]] inline ~Locker() { unlock(); }
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[[gnu::always_inline]] inline void unlock() { m_lock.unlock(); }
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[[gnu::always_inline]] inline void lock() { m_lock.lock(); }
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private:
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Lock& m_lock;
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};
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[[gnu::always_inline]] inline void Lock::lock()
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{
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int tid = gettid();
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for (;;) {
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if (CAS(&m_lock, 1, 0) == 0) {
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if (m_holder == -1 || m_holder == tid) {
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m_holder = tid;
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++m_level;
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memory_barrier();
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m_lock = 0;
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return;
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}
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m_lock = 0;
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}
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donate(m_holder);
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}
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}
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inline void Lock::unlock()
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{
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for (;;) {
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if (CAS(&m_lock, 1, 0) == 0) {
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ASSERT(m_holder == gettid());
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ASSERT(m_level);
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--m_level;
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if (m_level) {
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memory_barrier();
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m_lock = 0;
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return;
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}
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m_holder = -1;
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memory_barrier();
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m_lock = 0;
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return;
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}
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donate(m_holder);
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}
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}
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#define LOCKER(lock) LibThread::Locker locker(lock)
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template<typename T>
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class Lockable {
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public:
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Lockable() {}
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Lockable(T&& resource)
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: m_resource(move(resource))
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{
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}
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Lock& lock() { return m_lock; }
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T& resource() { return m_resource; }
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T lock_and_copy()
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{
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LOCKER(m_lock);
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return m_resource;
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}
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private:
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T m_resource;
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Lock m_lock;
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};
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}
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#else
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namespace LibThread {
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class Lock {
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public:
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Lock() { }
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~Lock() { }
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};
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}
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#define LOCKER(x)
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#endif
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