Reading a file generated by fire. More...

#include <Reader.h>

Inheritance diagram for fire::io::h5::Reader:

Collaboration diagram for fire::io::h5::Reader:

Classes
class	Buffer
	Read buffer allowing individual element access from a dataset. More...

class	BufferHandle
	Type-less handle to the Buffer. More...

class	MirrorObject
	A mirror event object. More...

Public Member Functions
	Reader (const std::string &name)
	Open the file in read mode. More...

virtual void	load_into (BaseData &d) final override
	Load the next event into the passed data. More...

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

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

virtual std::string	name () const final override
	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::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 final override
	Get the number of entries in the file. More...

std::size_t	runs () const final override
	Get the number of runs in the file. More...

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

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

template<typename AtomicType >
void	load (const std::string &path, AtomicType &val)
	Try to load a single value of an atomic type into the input handle. More...

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

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

Public Member Functions inherited from fire::io::Reader
	Reader (const std::string &file_name)
	open the file at the passed location More...

virtual	~Reader ()=default
	virtual destructor so derived classes can be closed

virtual void	copy (long unsigned int i_entry, const std::string &path, Writer &output)
	Copy the input object into the output file. More...

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

Private Attributes
HighFive::File	file_
	our highfive file

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

const std::size_t	runs_
	the number of runs in this file, set in constructor

std::size_t	rows_per_chunk_ {10000}
	the number of rows to keep in each chunk, read from DataSet?

std::unordered_map< std::string, std::unique_ptr< BufferHandle > >	buffers_
	our in-memory buffers for the data to be read in from disk

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

Additional Inherited Members
Public Types inherited from fire::io::Reader
using	Factory = ::fire::factory::Factory< Reader, std::unique_ptr< Reader >, const std::string & >
	Type of factory used to create readers.

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()

fire::io::h5::Reader::Reader ( const std::string & name )

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 the size of the data set at constants::EVENT_GROUP / constants::EVENT_HEADER_NAME / constants::NUMBER_NAME This is reliable as long as

EventHeader attaches the event number (or a similar once-per-event atomic type) under the name constants::EVENT_HEADER_NUMBER
The EventHeader is created under a io::Data named constants::EVENT_GROUP/constants::EVENT_HEADER_NAME

We inspect the size of the dataset located at constants::RUN_HEADER_NAME/constants::NUMBER_NAME in the file to get the number of runs. This will work as long as

The RunHeader is written to the file as RUN_HEADER_NAME.
The RunHeader attaches an atomic type member under the name number

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 > > fire::io::h5::Reader::availableObjects ( )

finaloverridevirtual

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 }

Implements fire::io::Reader.

◆ canCopy()

virtual bool fire::io::h5::Reader::canCopy ( ) const

inlinefinaloverridevirtual

We can copy.

Returns: true

Reimplemented from fire::io::Reader.

◆ copy()

virtual void fire::io::h5::Reader::copy	(	unsigned long int	i_entry,
		const std::string &	path,
		Writer &	output
	)

finaloverridevirtual

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]	path	full event object name
[in]	output	handle to the writer writing the output file

◆ entries()

std::size_t fire::io::h5::Reader::entries ( ) const

inlinefinaloverridevirtual

Get the number of entries in the file.

This value was determined upon construction.

Returns: number of events within the file

Implements fire::io::Reader.

◆ getDataSetType()

HighFive::DataType fire::io::h5::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 fire::io::h5::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 fire::io::h5::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 > fire::io::h5::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

◆ load()

template<typename AtomicType >

void fire::io::h5::Reader::load	(	const std::string &	path,
		AtomicType &	val
	)

inline

Try to load a single value of an atomic type into the input handle.

If the input path does not exist in our list of buffers, then we create a new buffer for the requested type and load the first chunk of data into memory.

Besides that, we access the Buffer and call its Buffer::read method, allowing the Buffer to handle the necessary disk reading operations.

Exceptions

std::bad_cast	if mismatched type is passed
HighFive::DataSetException	if requested dataset doesn't exist

Parameters

[in]	path	Full in-file path to dataset to load
[out]	val	Set to the next entry in the dataset

◆ load_into()

void fire::io::h5::Reader::load_into ( BaseData & d )

finaloverridevirtual

Load the next event into the passed data.

As instructed by fire::io::Reader, we simply call the data's load function with a reference to ourselves.

Parameters

[in] d Data to load data into

Implements fire::io::Reader.

◆ mirror()

void fire::io::h5::Reader::mirror	(	const std::string &	path,
		Writer &	output
	)

private

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

Parameters

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

◆ name()

std::string fire::io::h5::Reader::name ( ) const

finaloverridevirtual

Get the name of this file.

Returns: name of the file we are reading

Implements fire::io::Reader.

◆ runs()

std::size_t fire::io::h5::Reader::runs ( ) const

inlinefinaloverridevirtual

Get the number of runs in the file.

This value was determined upon construction

Returns: number of runs within the file

Implements fire::io::Reader.

◆ type()

std::pair< std::string, int > fire::io::h5::Reader::type ( const std::string & path )

finaloverridevirtual

Get the type of the input object.

We retrieve the attributes named TYPE_ATTR_NAME and VERS_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 and its version number

Implements fire::io::Reader.

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

include/fire/io/h5/Reader.h
src/fire/io/h5/Reader.cxx

Classes

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ Reader()

Member Function Documentation

◆ availableObjects()

◆ canCopy()

◆ copy()

◆ entries()

◆ getDataSetType()

◆ getH5ObjectType()

◆ getTypeName()

◆ list()

◆ load()

◆ load_into()

◆ mirror()

◆ name()

◆ runs()

◆ type()