Reading a file generated by fire. More...

#include <Reader.h>

Collaboration diagram for hdtree::Reader:

Classes
class	MirrorObject
	A mirror event object. More...

Public Member Functions
	Reader (const std::pair< std::string, std::string > &file_tree_path, bool inplace=false)
	Open the file in read mode. More...

virtual std::vector< std::pair< std::string, std::string > >	availableObjects ()
	Get the event objects available in the file. More...

virtual std::pair< std::string, int >	type (const std::string &branch_name)
	Get the type of the input object. More...

virtual std::string	name () const
	Get the name of this file. More...

std::vector< std::string >	list (const std::string &group_path) const
	List the entries inside of a group. More...

HighFive::DataSet	getDataSet (const std::string &branch_name) const
	Get data set.

HighFive::DataType	getDataSetType (const std::string &dataset) const
	Deduce the type of the dataset requested. More...

HighFive::ObjectType	getH5ObjectType (const std::string &path) const
	Get the H5 type of object at the input path. More...

std::string	getTypeName (const std::string &obj_name) const
	Get the 'type' attribute from the input group name. More...

std::size_t	entries () const
	Get the number of entries in the file. More...

virtual bool	canCopy () const
	We can copy. More...

virtual void	copy (unsigned long int i_entry, const std::string &branch_name, Writer &output)
	Copy the input data set to the output file. More...

	Reader (const Reader &)=delete
	never want to copy a reader

void	operator= (const Reader &)=delete
	never want to copy a reader

Private Member Functions
void	mirror (const std::string &branch_name, Writer &output)
	Mirror the structure of the passed branch_name from us into the output file. More...

Private Attributes
HighFive::File	file_
	our highfive file

HighFive::Group	tree_
	the HighFive group that is our HDTree

std::size_t	entries_
	the number of entries in this file, set in constructor

std::unordered_map< std::string, std::unique_ptr< MirrorObject > >	mirror_objects_
	our in-memory mirror objects for data being copied to the output file without processing

Detailed Description

Reading a file generated by fire.

See also: Writer for our files are written with fire

This reader handles the buffering of data read in from an HDF5 file in a seamless manner so that individual entries can be requested at a time without making disk read operation each time Reader::load is called.

Constructor & Destructor Documentation

◆ Reader()

hdtree::Reader::Reader	(	const std::pair< std::string, std::string > &	file_tree_path,
		bool	inplace = `false`
	)

Open the file in read mode.

Our read mode is the same as HDF5 Read Only mode

We also read the number of entries in this file by retrieving size attribute of the HDTree. This is reliable as long as the HDTree was written/flushed before program termination.

Exceptions

HighFive::Exception if file is not accessible.

Parameters

[in] name file name to open and read

Member Function Documentation

◆ availableObjects()

std::vector< std::pair< std::string, std::string > > hdtree::Reader::availableObjects ( )

virtual

Get the event objects available in the file.

We crawl the internal directory structure of the file we have open.

See also: type for how we get the name of the class that was used to write the data

Returns: vector of string pairs { obj_name, pass }

◆ canCopy()

virtual bool hdtree::Reader::canCopy ( ) const

inlinevirtual

We can copy.

Returns: true

◆ copy()

void hdtree::Reader::copy	(	unsigned long int	i_entry,
		const std::string &	branch_name,
		Writer &	output
	)

virtual

Copy the input data set to the output file.

This happens when the input data set has passed all of the drop/keep rules so it is supposed to be copied into the output file; however, noone has accessed it with Event::get yet so an in-memory class object has not been created for it yet.

Parameters

[in]	i_entry	entry we are currently on
[in]	branch_name	full event object name
[in]	output	handle to the writer writing the output file

this is where recursing into the subgroups of full_name occurs if this mirror object hasn't been created yet

If a mirror object is being created that means the event object satisfies the following:

The event object exists in the input file
The event object should be written to the output file
The event object HAS NOT been accessed during the processing of this input file yet

This means we should copy over the structure of this event object from the input file into the output file.

◆ entries()

std::size_t hdtree::Reader::entries ( ) const

inline

Get the number of entries in the file.

This value was determined upon construction.

Returns: number of events within the file

◆ getDataSetType()

HighFive::DataType hdtree::Reader::getDataSetType ( const std::string & dataset ) const

Deduce the type of the dataset requested.

Note: This is low-level and is only being used in io::ParameterStorage for more flexibility in the parameter maps.

Parameters

[in] dataset full in-file path to H5 dataset

Returns: HighFive::DataType specifying the atomic type of the set

◆ getH5ObjectType()

HighFive::ObjectType hdtree::Reader::getH5ObjectType ( const std::string & path ) const

Get the H5 type of object at the input path.

Parameters

[in] path in-file path to an HDF5 object

Returns: HighFive::ObjectType defining the type that the object there is

◆ getTypeName()

std::string hdtree::Reader::getTypeName ( const std::string & obj_name ) const

Get the 'type' attribute from the input group name.

We retrieve the attribute named TYPE_ATTR_NAME from the group located at EVENT_GROUP/obj_name. This enables us to construct the list of products within an inputfile in Event::setInputFile.

See also: io::Writer::setTypeName for where the type attr is set

Parameters

[in] obj_name Name of event object to retrieve type of

Returns: demangled type name in string format

◆ list()

std::vector< std::string > hdtree::Reader::list ( const std::string & group_path ) const

List the entries inside of a group.

Note: This is low-level and is only being used in io::ParameterStorage for more flexibility in the parameter maps and Event::setInputFile to obtain the event products within a file.

Parameters

[in] group_path full in-file path to H5 group to list elements of

Returns: list of elements in the group, empty if group does not exist

◆ mirror()

void hdtree::Reader::mirror	(	const std::string &	branch_name,
		Writer &	output
	)

private

Mirror the structure of the passed branch_name from us into the output file.

Parameters

[in]	branch_name	path to the group (and potential subgroups) to mirror
[in]	output	output file to mirror this structure to

◆ name()

std::string hdtree::Reader::name ( ) const

virtual

Get the name of this file.

Returns: name of the file we are reading

◆ type()

std::pair< std::string, int > hdtree::Reader::type ( const std::string & branch_name )

virtual

Get the type of the input object.

We retrieve the attributes named TYPE_ATTR_NAME and VERS_ATTR_NAME from the group located at branch_name within the tree.

See also: io::Writer::setTypeName for where the type attr is set

Parameters

[in] branch_name Name of event object to retrieve type of

Returns: demangled type name in string format and its version number

The documentation for this class was generated from the following files:

cpp/include/hdtree/Reader.h
cpp/src/Reader.cxx

Classes

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ Reader()

Member Function Documentation

◆ availableObjects()

◆ canCopy()

◆ copy()

◆ entries()

◆ getDataSetType()

◆ getH5ObjectType()

◆ getTypeName()

◆ list()

◆ mirror()

◆ name()

◆ type()