From 6a15b2379f90ba4f9222fea0a5f8c12e8cecbae5 Mon Sep 17 00:00:00 2001 From: Isaac Chen Date: Fri, 13 Jul 2018 10:12:35 +0800 Subject: wayne: Import GPS * QC Tag: LA.UM.6.2.r1-06100-sdm660.0 Change-Id: I26da3b90caa473ed5f88408627463ec7f7655f23 Signed-off-by: Isaac Chen --- gps/utils/LocSharedLock.h | 59 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) create mode 100644 gps/utils/LocSharedLock.h (limited to 'gps/utils/LocSharedLock.h') diff --git a/gps/utils/LocSharedLock.h b/gps/utils/LocSharedLock.h new file mode 100644 index 0000000..7fe6237 --- /dev/null +++ b/gps/utils/LocSharedLock.h @@ -0,0 +1,59 @@ +/* Copyright (c) 2015, The Linux Foundation. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following + * disclaimer in the documentation and/or other materials provided + * with the distribution. + * * Neither the name of The Linux Foundation, nor the names of its + * contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS + * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR + * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, + * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE + * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN + * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + */ +#ifndef __LOC_SHARED_LOCK__ +#define __LOC_SHARED_LOCK__ + +#include +#include +#include + +// This is a utility created for use cases such that there are more than +// one client who need to share the same lock, but it is not predictable +// which of these clients is to last to go away. This shared lock deletes +// itself when the last client calls its drop() method. To add a cient, +// this share lock's share() method has to be called, so that the obj +// can maintain an accurate client count. +class LocSharedLock { + volatile int32_t mRef; + pthread_mutex_t mMutex; + inline ~LocSharedLock() { pthread_mutex_destroy(&mMutex); } +public: + // first client to create this LockSharedLock + inline LocSharedLock() : mRef(1) { pthread_mutex_init(&mMutex, NULL); } + // following client(s) are to *share()* this lock created by the first client + inline LocSharedLock* share() { android_atomic_inc(&mRef); return this; } + // whe a client no longer needs this shared lock, drop() shall be called. + inline void drop() { if (1 == android_atomic_dec(&mRef)) delete this; } + // locking the lock to enter critical section + inline void lock() { pthread_mutex_lock(&mMutex); } + // unlocking the lock to leave the critical section + inline void unlock() { pthread_mutex_unlock(&mMutex); } +}; + +#endif //__LOC_SHARED_LOCK__ -- cgit v1.2.3