Buffer.h

/*
 * Copyright (c) 2008-2014, Pedigree Developers
 *
 * Please see the CONTRIB file in the root of the source tree for a full
 * list of contributors.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
#ifndef KERNEL_UTILITIES_BUFFER_H
#define KERNEL_UTILITIES_BUFFER_H
#include "pedigree/kernel/Atomic.h"
#include "pedigree/kernel/compiler.h"
#include "pedigree/kernel/process/ConditionVariable.h"
#include "pedigree/kernel/process/Event.h"
#include "pedigree/kernel/process/Mutex.h"
#include "pedigree/kernel/process/TerminationDeferral.h"
#include "pedigree/kernel/processor/types.h"
#include "pedigree/kernel/utilities/BufferMonitors.h"
#include "pedigree/kernel/utilities/List.h"
#include "pedigree/kernel/utilities/new"
 
#include <config.h>
 
class Semaphore;
class Thread;
 
template <class T, bool allowShortOperation = false>
class EXPORTED_PUBLIC Buffer {
  friend class UnixSocket;  // to allow for calling notifyMonitors()
 
 public:
  Buffer(size_t bufferSize);
  ~Buffer();
 
  size_t write(const T* buffer, size_t count, bool block = true);
 
  size_t writeAvailable(const T* buffer, size_t count, bool atomic = false);
 
  size_t writeAtomic(const T* buffer, size_t count, bool block = true);
 
  bool tryWrite(const T* buffer, size_t count);
 
  size_t read(T* buffer, size_t count, bool block = true);
 
  void disableWrites();
 
  void disableReads();
 
  bool enableWrites();
 
  bool enableReads();
 
  size_t getDataSize();
 
  size_t getSize();
 
  bool canWrite(bool block);
 
  bool canRead(bool block);
 
  uint64_t readableGeneration() const;
  uint64_t writableGeneration() const;
 
  void wipe();
 
  void monitor(Thread* pThread, Event* pEvent);
 
  void monitor(Semaphore* pSemaphore);
 
  void cullMonitorTargets(Thread* pThread);
 
  void cullMonitorTargets(Semaphore* pSemaphore);
 
  void cullMonitorTargets(Event* pEvent);
 
#if HOSTED && PEDIGREE_HOSTED_SMOKE_TESTS
  void acquireHostedOperationLock();
  void releaseHostedOperationLock();
  size_t getHostedActiveOperationCount();
#endif
 
 private:
  WITHOUT_IMPLICIT_CONSTRUCTORS(Buffer);
 
  class ActiveOperation {
   public:
    explicit ActiveOperation(Buffer& buffer)
        : m_TerminationDeferral(), m_Buffer(buffer.beginOperation() ? &buffer : nullptr) {}
 
    ~ActiveOperation() {
      if (m_Buffer) {
        m_Buffer->endOperation();
      }
    }
 
    explicit operator bool() const {
      return m_Buffer != nullptr;
    }
 
   private:
    ActiveOperation(const ActiveOperation&) = delete;
    ActiveOperation& operator=(const ActiveOperation&) = delete;
 
    TerminationDeferral m_TerminationDeferral;
    Buffer* m_Buffer;
  };
 
  bool beginOperation();
  void endOperation();
 
  void notifyMonitors();
 
  void notifyMonitorsLocked();
 
  size_t writeLocked(const T* buffer, size_t count);
 
  void addSegment(const T* buffer, size_t count);
 
  static const size_t m_SegmentSize = 32768;
 
  struct Segment {
    Segment() : data(), reader(0), size(0) {}
 
    T data[m_SegmentSize];
 
    size_t reader;
 
    size_t size;
  };
 
  size_t m_BufferSize;
  size_t m_DataSize;
  Atomic<uint64_t> m_ReadableGeneration;
  Atomic<uint64_t> m_WritableGeneration;
 
  Mutex m_Lock;
 
  ConditionVariable m_WriteCondition;
  ConditionVariable m_ReadCondition;
  ConditionVariable m_DrainCondition;
 
  List<Segment*> m_Segments;
  BufferMonitors m_Monitors;
 
  bool m_bCanRead;
  bool m_bCanWrite;
  bool m_bClosing;
  size_t m_ActiveOperations;
};
 
// Specializations are in a .cc file.
extern template class Buffer<uint8_t, false>;  // IWYU pragma: keep
extern template class Buffer<uint8_t, true>;   // IWYU pragma: keep
extern template class Buffer<char, false>;     // IWYU pragma: keep
extern template class Buffer<char, true>;      // IWYU pragma: keep
extern template class Buffer<size_t, false>;   // IWYU pragma: keep
extern template class Buffer<size_t, true>;    // IWYU pragma: keep
 
#endif  // KERNEL_UTILITIES_BUFFER_H