remove bthread/sys_futex.cpp

src/bthread/sys_futex.cpp

-// bthread - A M:N threading library to make applications more concurrent.
-// Copyright (c) 2012 Baidu, Inc.
-// 
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-// 
-//     http://www.apache.org/licenses/LICENSE-2.0
-// 
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// Author: Ge,Jun (gejun@baidu.com)
-// Date: Tue Jul 10 17:40:58 CST 2012
-
-#include "bthread/sys_futex.h"
-
-namespace bthread {
-
-const int SYS_FUTEX_PRIVATE_FLAG = 128;
-
-static int get_futex_private_flag() {
-    static int dummy = 0;
-    if (!syscall(SYS_futex, &dummy, (FUTEX_WAKE | SYS_FUTEX_PRIVATE_FLAG),
-                 1, NULL, NULL, 0)) {
-        return SYS_FUTEX_PRIVATE_FLAG;
-    }
-    return 0;
-}
-
-extern const int futex_private_flag = get_futex_private_flag();
-
-}  // namespace bthread

src/bthread/sys_futex.h

@@ -26,21 +26,23 @@
 
 namespace bthread {
 
-extern const int futex_private_flag;
+#ifndef FUTEX_PRIVATE_FLAG
+#define FUTEX_PRIVATE_FLAG 128
+#endif
 
 inline int futex_wait_private(
     void* addr1, int expected, const timespec* timeout) {
-    return syscall(SYS_futex, addr1, (FUTEX_WAIT | futex_private_flag),
+    return syscall(SYS_futex, addr1, (FUTEX_WAIT | FUTEX_PRIVATE_FLAG),
                    expected, timeout, NULL, 0);
 }
 
 inline int futex_wake_private(void* addr1, int nwake) {
-    return syscall(SYS_futex, addr1, (FUTEX_WAKE | futex_private_flag),
+    return syscall(SYS_futex, addr1, (FUTEX_WAKE | FUTEX_PRIVATE_FLAG),
                    nwake, NULL, NULL, 0);
 }
 
 inline int futex_requeue_private(void* addr1, int nwake, void* addr2) {
-    return syscall(SYS_futex, addr1, (FUTEX_REQUEUE | futex_private_flag),
+    return syscall(SYS_futex, addr1, (FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG),
                    nwake, NULL, addr2, 0);
 }