From 31c401a5ccee4a821e4d77f5c1f1883b1aac70e3 Mon Sep 17 00:00:00 2001
From: weiyu <weiyuluo1232@gmail.com>
Date: Tue, 28 May 2019 16:56:49 -0700
Subject: [PATCH] implement futex.cc

---
 futex.cc | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 futex.cc

diff --git a/futex.cc b/futex.cc
new file mode 100644
index 00000000..64ec6b4a
--- /dev/null
+++ b/futex.cc
@@ -0,0 +1,70 @@
+// futex -*- C++ -*-
+
+// Copyright (C) 2015-2019 Free Software Foundation, Inc.
+//
+// This is a reimplementation of libstdc++-v3/src/c++11/futex.cc. 
+
+#include <bits/atomic_futex.h>
+#ifdef _GLIBCXX_HAS_GTHREADS
+#if defined(_GLIBCXX_HAVE_LINUX_FUTEX) && ATOMIC_INT_LOCK_FREE > 1
+#include <chrono>
+#include <climits>
+#include <syscall.h>
+#include <unistd.h>
+#include <sys/time.h>
+#include <errno.h>
+#include <debug/debug.h>
+
+#include "model.h"
+#include "execution.h"
+#include "mutex.h"
+#include <condition_variable>
+
+// Constants for the wait/wake futex syscall operations
+const unsigned futex_wait_op = 0;
+const unsigned futex_wake_op = 1;
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+	bool
+	__atomic_futex_unsigned_base::_M_futex_wait_until(unsigned *__addr,
+		unsigned __val,
+		bool __has_timeout, chrono::seconds __s, chrono::nanoseconds __ns)
+	{
+		// do nothing if the two values are not equal
+		if ( *__addr != __val ) {
+			return true;
+		}
+
+		// if a timeout is specified, return immedialy. Letting the scheduler decide how long this thread will wait.  
+		if (__has_timeout) {
+			return true;
+		}
+
+		ModelExecution *execution = model->get_execution();
+
+		cdsc::condition_variable *v = new cdsc::condition_variable();
+		cdsc::mutex *m = new cdsc::mutex();
+
+		execution->cond_map.put( (pthread_cond_t *) __addr, v);
+		execution->mutex_map.put( (pthread_mutex_t *) __addr, m);
+
+		v->wait(*m);
+		return true;
+	}
+
+	void
+	__atomic_futex_unsigned_base::_M_futex_notify_all(unsigned* __addr)
+	{
+		// INT_MAX wakes all the waiters at the address __addr
+		ModelExecution *execution = model->get_execution();
+		cdsc::condition_variable *v = execution->cond_map.get( (pthread_cond_t *) __addr);
+		v->notify_all();
+	}
+
+_GLIBCXX_END_NAMESPACE_VERSION
+}
+#endif // defined(_GLIBCXX_HAVE_LINUX_FUTEX) && ATOMIC_INT_LOCK_FREE > 1
+#endif // _GLIBCXX_HAS_GTHREADS
-- 
2.34.1