src/type3_AndroidCloud/anbox-master/src/anbox/common/message_channel.cpp

   1 // Copyright 2014 The Android Open Source Project
   2 //
   3 // Licensed under the Apache License, Version 2.0 (the "License");
   4 // you may not use this file except in compliance with the License.
   5 // You may obtain a copy of the License at
   6 //
   7 // http://www.apache.org/licenses/LICENSE-2.0
   8 //
   9 // Unless required by applicable law or agreed to in writing, software
  10 // distributed under the License is distributed on an "AS IS" BASIS,
  11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 // See the License for the specific language governing permissions and
  13 // limitations under the License.
  14
  15 #include "anbox/common/message_channel.h"
  16
  17 namespace anbox {
  18 namespace common {
  19 MessageChannelBase::MessageChannelBase(size_t capacity) : pos_(0U),
  20                                                           count_(0U),
  21                                                           capacity_(capacity),
  22                                                           lock_(),
  23                                                           can_read_(),
  24                                                           can_write_() {}
  25
  26 MessageChannelBase::~MessageChannelBase() {}
  27
  28 size_t MessageChannelBase::before_write() {
  29   std::unique_lock<std::mutex> l(lock_, std::defer_lock);
  30   lock_.lock();
  31
  32   while (count_ >= capacity_)
  33     can_write_.wait(l);
  34
  35   size_t result = pos_ + count_;
  36   if (result >= capacity_)
  37     result -= capacity_;
  38
  39   return result;
  40 }
  41
  42 void MessageChannelBase::after_write() {
  43   count_++;
  44   can_read_.notify_one();
  45   lock_.unlock();
  46 }
  47
  48 size_t MessageChannelBase::before_read() {
  49   std::unique_lock<std::mutex> l(lock_, std::defer_lock);
  50   lock_.lock();
  51   while (count_ == 0)
  52     can_read_.wait(l);
  53   return pos_;
  54 }
  55
  56 void MessageChannelBase::after_read() {
  57   if (++pos_ == capacity_)
  58     pos_ = 0U;
  59   count_--;
  60   can_write_.notify_one();
  61   lock_.unlock();
  62 }
  63 }  // namespace common
  64 }  // namespace anbox