text: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.
   */
  
  // A stub implementation of shared memory for systems where unavailable.
  // Fails all the operations.
  
  #include "pagespeed/kernel/base/null_shared_mem.h"
  
  #include "base/logging.h"
  #include "pagespeed/kernel/base/message_handler.h"
  
  namespace net_instaweb {
  
  NullSharedMem::NullSharedMem() {}
  
  NullSharedMem::~NullSharedMem() {}
  
  size_t NullSharedMem::SharedMutexSize() const { return 1; }
  
  AbstractSharedMemSegment* NullSharedMem::CreateSegment(
      const GoogleString& name, size_t size, MessageHandler* handler) {
    handler->MessageS(kWarning, "Using null shared memory runtime.");
    return nullptr;
  }
  
  AbstractSharedMemSegment* NullSharedMem::AttachToSegment(
      const GoogleString& name, size_t size, MessageHandler* handler) {
    return nullptr;
  }
  
  void NullSharedMem::DestroySegment(const GoogleString& name,
                                     MessageHandler* handler) {
    // Bug-free client code should never call our DestroySegment since
    // Create/Attach will fail.
    LOG(DFATAL) << "Trying to destroy a segment that was never allocated:"
                << name;
  }
  
  }  // namespace net_instaweb
  