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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CONTENT_BROWSER_DEVICE_SENSORS_DATA_FETCHER_SHARED_MEMORY_BASE_H_
#define CONTENT_BROWSER_DEVICE_SENSORS_DATA_FETCHER_SHARED_MEMORY_BASE_H_
#include <map>
#include "base/memory/scoped_ptr.h"
#include "base/memory/shared_memory.h"
#include "base/message_loop/message_loop.h"
#include "content/browser/device_sensors/device_sensors_consts.h"
#include "content/common/content_export.h"
namespace content {
// Sensor data fetchers should derive from this base class and implement
// the abstract Start() and Stop() methods.
// If the fetcher requires polling it should also implement IsPolling()
// to return true and the Fetch() method which will be called from the
// polling thread to fetch data at regular intervals.
class CONTENT_EXPORT DataFetcherSharedMemoryBase {
public:
// Starts updating the shared memory buffer with sensor data at
// regular intervals. Returns true if the relevant sensors could
// be successfully activated.
bool StartFetchingDeviceData(ConsumerType consumer_type);
// Stops updating the shared memory buffer. Returns true if the
// relevant sensors could be successfully deactivated.
bool StopFetchingDeviceData(ConsumerType consumer_type);
// Should be called before destruction to make sure all active
// sensors are unregistered.
virtual void Shutdown();
// Returns the shared memory handle of the device sensor data
// duplicated into the given process. This method should only be
// called after a call to StartFetchingDeviceData method with
// corresponding |consumer_type| parameter.
base::SharedMemoryHandle GetSharedMemoryHandleForProcess(
ConsumerType consumer_type, base::ProcessHandle process);
enum FetcherType {
// Fetcher runs on the same thread as its creator.
FETCHER_TYPE_DEFAULT,
// Fetcher runs on a separate thread calling |Fetch()| at regular intervals.
FETCHER_TYPE_POLLING_CALLBACK,
// Fetcher runs on a separate thread, but no callbacks are executed.
FETCHER_TYPE_SEPARATE_THREAD
};
protected:
class PollingThread;
DataFetcherSharedMemoryBase();
virtual ~DataFetcherSharedMemoryBase();
// Returns the message loop of the polling thread.
// Returns NULL if there is no polling thread.
base::MessageLoop* GetPollingMessageLoop() const;
// If IsPolling() is true this method is called from the |polling_thread_|
// at regular intervals.
virtual void Fetch(unsigned consumer_bitmask);
// Returns the type of thread this fetcher runs on.
virtual FetcherType GetType() const;
// Returns the sensor sampling interval. In particular if this fetcher
// GetType() == FETCHER_TYPE_POLLING_CALLBACK the interval between
// successive calls to Fetch().
virtual base::TimeDelta GetInterval() const;
// Start() method should call InitSharedMemoryBuffer() to get the shared
// memory pointer. If IsPolling() is true both Start() and Stop() methods
// are called from the |polling_thread_|.
virtual bool Start(ConsumerType consumer_type, void* buffer) = 0;
virtual bool Stop(ConsumerType consumer_type) = 0;
bool IsPollingTimerRunningForTesting() const;
private:
bool InitAndStartPollingThreadIfNecessary();
base::SharedMemory* GetSharedMemory(ConsumerType consumer_type);
void* GetSharedMemoryBuffer(ConsumerType consumer_type);
unsigned started_consumers_;
scoped_ptr<PollingThread> polling_thread_;
// Owning pointers. Objects in the map are deleted in dtor.
typedef std::map<ConsumerType, base::SharedMemory*> SharedMemoryMap;
SharedMemoryMap shared_memory_map_;
DISALLOW_COPY_AND_ASSIGN(DataFetcherSharedMemoryBase);
};
} // namespace content
#endif // CONTENT_BROWSER_DEVICE_SENSORS_DATA_FETCHER_SHARED_MEMORY_BASE_H_