ByteSource.h

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// Copyright 2019-2026 CERN and copyright holders of ALICE O2.
// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
// All rights not expressly granted are reserved.
//
// This software is distributed under the terms of the GNU General Public
// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
//
// In applying this license CERN does not waive the privileges and immunities
// granted to it by virtue of its status as an Intergovernmental Organization
// or submit itself to any jurisdiction.
 
#ifndef O2_FRAMEWORK_AODNATIVE_BYTESOURCE_H_
#define O2_FRAMEWORK_AODNATIVE_BYTESOURCE_H_
 
#include <cstddef>
#include <cstdint>
#include <memory>
#include <span>
#include <string>
 
namespace o2::aod::native
{
 
struct Options {
  enum struct LocalIO { MMap,
                        PRead };
  enum struct RemoteIO { Prefetch,
                         Stream };
  enum struct HttpVersion { Auto,
                            Http1_1,
                            Http2 };
  LocalIO localIO = LocalIO::MMap;
  RemoteIO remoteIO = RemoteIO::Prefetch;
  int threads = 1;
  int prefetchDepth = 1;
  size_t coalesceGap = 64 * 1024;
  double spanFraction = 0.8;
  int streamWindows = 4;
  size_t streamWindowBytes = 2 * 1024 * 1024;
  HttpVersion httpVersion = HttpVersion::Auto;
  int httpConnections = 4;
};
 
struct ReadRequest {
  uint64_t offset;
  size_t length;
  void* dst;
};
 
class ByteSource
{
 public:
  virtual ~ByteSource();
  virtual uint64_t size() const = 0;
  virtual void readInto(uint64_t off, size_t len, void* dst) = 0;
  virtual void readvInto(std::span<ReadRequest> requests) = 0;
  virtual std::span<const uint8_t> tryMap(uint64_t off, size_t len) { return {}; }
  virtual bool canMap() const { return false; }
  virtual bool isRemote() const { return false; }
  virtual void willNeed(uint64_t off, size_t len) {}
  virtual void dontNeed(uint64_t off, size_t len) {}
  virtual uint64_t bytesRead() const = 0;
  virtual uint64_t readCalls() const = 0;
  virtual std::string url() const = 0;
  static std::unique_ptr<ByteSource> open(std::string url, const Options&);
};
 
} // namespace o2::aod::native
 
#endif // O2_FRAMEWORK_AODNATIVE_BYTESOURCE_H_