Factory.cpp

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/*
 * (C) Copyright 2020-2021 UCAR
 *
 * This software is licensed under the terms of the Apache Licence Version 2.0
 * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
 */
 
#include "ioda/Engines/Factory.h"
 
#include <string>
 
#include "ioda/Engines/HH.h"
#include "ioda/Engines/ObsStore.h"
#include "ioda/Exception.h"
#include "ioda/Group.h"
#include "ioda/defs.h"
 
namespace ioda {
namespace Engines {
Group constructFromCmdLine(int argc, char** argv, const std::string& defaultFilename) {
  /* Options:
  Start with --ioda-engine-options. All options after this are
  positional options.
 
  --ioda-engine-options name parameters...
 
  Currently supported engine names:
  1. HDF5 with file backend [HDF5-file]
  2. HDF5 in-memory backend [HDF5-mem]
3. ObsStore in-memory backend [obs-store]
 
  Engine parameters:
  1. Needs a file name, file opening properties [create, open],
     access mode [read, read_write, create, truncate].
  2. Needs a file name, file size increment length (in MB), flush_on_close (bool).
  3. None
  */
  BackendCreationParameters params;
  BackendNames backendName;
 
  using std::string;
  std::vector<string> opts(argc);
  for (size_t i = 0; i < (size_t)argc; ++i) opts[i] = string(argv[i]);
 
  // Find the "--ioda-engine-options" option.
  // If none is specified, use a default.
  auto it = std::find(opts.cbegin(), opts.cend(), "--ioda-engine-options");
  if (it == opts.cend()) {
    // No options --> create a file using the defaultFileName
    backendName       = BackendNames::Hdf5File;
    params.fileName   = defaultFilename;
    params.action     = BackendFileActions::Create;
    params.createMode = BackendCreateModes::Truncate_If_Exists;
  } else {
    ++it;
    if (it == opts.cend()) {
      throw Exception("Bad option --ioda-engine-options. Got the "
        "--ioda-engine-options token but nothing else.", ioda_Here());
    }
 
    // convert array of c-string options into vector of strings
    auto readOpts = [&opts, &it](size_t n) -> std::vector<string> {
      std::vector<string> res(n);
      for (size_t i = 0; i < n; ++i) {
        ++it;
        if (it == opts.cend())
          throw Exception("Bad option --ioda-engine-options. "
            "Wrong number of elements.", ioda_Here()).add("Expected", n);
        res[i] = std::string(*it);
      }
      return res;
    };
 
    string sEngine = *it;
    if (sEngine == "HDF5-file") {
      auto engineOpts = readOpts(3);
      backendName     = BackendNames::Hdf5File;
      params.fileName = engineOpts[0];
 
      enum class open_or_create {
        open,
        create
      } action
        = (engineOpts[1] == "create") ? open_or_create::create : open_or_create::open;
      if (action == open_or_create::open) {
        // open action
        params.action   = BackendFileActions::Open;
        params.openMode = (engineOpts[2] == "read_write") ? BackendOpenModes::Read_Write
                                                          : BackendOpenModes::Read_Only;
      } else {
        // create action
        params.action     = BackendFileActions::Create;
        params.createMode = (engineOpts[2] == "truncate") ? BackendCreateModes::Truncate_If_Exists
                                                          : BackendCreateModes::Fail_If_Exists;
      }
    } else if (sEngine == "HDF5-mem") {
      auto engineOpts = readOpts(3);
      // TODO(ryan): Allow open / create
      // enum class open_or_create { open, create } action
      //    = (engineOpts[1] == "create") ? open_or_create::create :
      //    open_or_create::open;
 
      backendName       = BackendNames::Hdf5Mem;
      params.fileName   = engineOpts[0];
      params.action     = BackendFileActions::Create;
      params.createMode = BackendCreateModes::Truncate_If_Exists;
 
      string sAllocLen_MB = engineOpts[1];
      string sFlush       = engineOpts[2];
 
      params.allocBytes = gsl::narrow<size_t>(((size_t)std::stoul(sAllocLen_MB)) * 1024 * 1024);
      params.flush      = (sFlush == "true");
    } else if (sEngine == "obs-store") {
      backendName = BackendNames::ObsStore;
    } else {
      throw Exception("Bad option --ioda-engine-options. "
              "Unknown engine.", ioda_Here()).add("Engine", sEngine);
    }
  }
  return constructBackend(backendName, params);
}
 
Group constructBackend(BackendNames name, BackendCreationParameters& params) {
  Group backend;
  if (name == BackendNames::Hdf5File) {
    if (params.action == BackendFileActions::Open)
      return HH::openFile(params.fileName, params.openMode);
    if (params.action == BackendFileActions::Create)
      return HH::createFile(params.fileName, params.createMode, HH::HDF5_Version_Range(HH::HDF5_Version::V18, HH::HDF5_Version::V110));
    throw Exception("Unknown BackendFileActions value", ioda_Here());
  }
  if (name == BackendNames::Hdf5Mem) {
    if (params.action == BackendFileActions::Open)
      return HH::openMemoryFile(params.fileName, params.openMode, params.flush, params.allocBytes);
    if (params.action == BackendFileActions::Create)
      return HH::createMemoryFile(params.fileName, params.createMode, params.flush,
                                  params.allocBytes);
    throw Exception("Unknown BackendFileActions value", ioda_Here());
  }
  if (name == BackendNames::ObsStore) return ObsStore::createRootGroup();
 
  // If we get to here, then we have a backend name that is
  // not implemented yet.
  throw Exception("Backend not implemented yet", ioda_Here());
}
}  // namespace Engines
}  // namespace ioda