The on-storage meta-data of an ntuple.
Represents the on-disk (on storage) information about an ntuple. The meta-data consists of a header and one or several footers. The header carries the ntuple schema, i.e. the fields and the associated columns and their relationships. The footer(s) carry information about one or several clusters. For every cluster, a footer stores its location and size, and for every column the range of element indexes as well as a list of pages and page locations.
The descriptor provide machine-independent (de-)serialization of headers and footers, and it provides lookup routines for ntuple objects (pages, clusters, ...). It is supposed to be usable by all RPageStorage implementations.
The serialization does not use standard ROOT streamers in order to not let it depend on libCore. The serialization uses the concept of frames: header, footer, and substructures have a preamble with version numbers and the size of the writte struct. This allows for forward and backward compatibility when the meta-data evolves.
Definition at line 272 of file RNTupleDescriptor.hxx.
Public Member Functions | |
RNTupleDescriptor ()=default | |
RNTupleDescriptor (const RNTupleDescriptor &other)=delete | |
RNTupleDescriptor (RNTupleDescriptor &&other)=default | |
DescriptorId_t | FindClusterId (DescriptorId_t columnId, NTupleSize_t index) const |
DescriptorId_t | FindColumnId (DescriptorId_t fieldId, std::uint32_t columnIndex) const |
DescriptorId_t | FindFieldId (std::string_view fieldName) const |
Searches for a top-level field. More... | |
DescriptorId_t | FindFieldId (std::string_view fieldName, DescriptorId_t parentId) const |
std::unique_ptr< RNTupleModel > | GenerateModel () const |
Re-create the C++ model from the stored meta-data. More... | |
std::string | GetAuthor () const |
const RClusterDescriptor & | GetClusterDescriptor (DescriptorId_t clusterId) const |
const RColumnDescriptor & | GetColumnDescriptor (DescriptorId_t columnId) const |
std::string | GetCustodian () const |
std::string | GetDescription () const |
const RFieldDescriptor & | GetFieldDescriptor (DescriptorId_t fieldId) const |
RNTupleUuid | GetGroupUuid () const |
std::string | GetName () const |
std::size_t | GetNClusters () const |
std::size_t | GetNColumns () const |
NTupleSize_t | GetNElements (DescriptorId_t columnId) const |
NTupleSize_t | GetNEntries () const |
std::size_t | GetNFields () const |
RNTupleUuid | GetOwnUuid () const |
std::chrono::system_clock::time_point | GetTimeStampData () const |
std::chrono::system_clock::time_point | GetTimeStampWritten () const |
RNTupleVersion | GetVersion () const |
RNTupleDescriptor & | operator= (const RNTupleDescriptor &other)=delete |
RNTupleDescriptor & | operator= (RNTupleDescriptor &&other)=default |
bool | operator== (const RNTupleDescriptor &other) const |
void | PrintInfo (std::ostream &output) const |
std::uint32_t | SerializeFooter (void *buffer) const |
Serializes cluster meta data. Returns the number of bytes and fills buffer if it is not nullptr. More... | |
std::uint32_t | SerializeHeader (void *buffer) const |
We deliberately do not use ROOT's built-in serialization in order to allow for use of RNTuple's without libCore Serializes the global ntuple information as well as the column and field schemata Returns the number of bytes and fills buffer if it is not nullptr. More... | |
Static Public Member Functions | |
static void | LocateMetadata (const void *postscript, std::uint32_t &szHeader, std::uint32_t &szFooter) |
Given kNBytesPostscript bytes, extract the header and footer lengths in bytes. More... | |
Static Public Attributes | |
static constexpr std::uint16_t | kFrameVersionCurrent = 0 |
In order to handle changes to the serialization routine in future ntuple versions. More... | |
static constexpr std::uint16_t | kFrameVersionMin = 0 |
static constexpr unsigned int | kNBytesPostscript = 16 |
The last few bytes after the footer store the length of footer and header. More... | |
static constexpr unsigned int | kNBytesPreamble = 8 |
The preamble is sufficient to get the length of the header. More... | |
Private Attributes | |
std::string | fAuthor |
The origin of the data. More... | |
std::unordered_map< DescriptorId_t, RClusterDescriptor > | fClusterDescriptors |
May contain only a subset of all the available clusters, e.g. More... | |
std::unordered_map< DescriptorId_t, RColumnDescriptor > | fColumnDescriptors |
std::string | fCustodian |
The current responsible for storing the data. More... | |
std::string | fDescription |
Free text from the user. More... | |
std::unordered_map< DescriptorId_t, RFieldDescriptor > | fFieldDescriptors |
RNTupleUuid | fGroupUuid |
Column sets that are created as derived sets from existing NTuples share the same group id. More... | |
std::string | fName |
The ntuple name needs to be unique in a given storage location (file) More... | |
RNTupleUuid | fOwnUuid |
Every NTuple gets a unique identifier. More... | |
std::chrono::system_clock::time_point | fTimeStampData |
The time stamp of the ntuple data (immutable) More... | |
std::chrono::system_clock::time_point | fTimeStampWritten |
The time stamp of writing the data to storage, which gets updated when re-written. More... | |
RNTupleVersion | fVersion |
The version evolves with the ntuple summary meta-data. More... | |
Friends | |
class | RNTupleDescriptorBuilder |
#include <ROOT/RNTupleDescriptor.hxx>
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ROOT::Experimental::DescriptorId_t ROOT::Experimental::RNTupleDescriptor::FindClusterId | ( | DescriptorId_t | columnId, |
NTupleSize_t | index | ||
) | const |
Definition at line 685 of file RNTupleDescriptor.cxx.
ROOT::Experimental::DescriptorId_t ROOT::Experimental::RNTupleDescriptor::FindColumnId | ( | DescriptorId_t | fieldId, |
std::uint32_t | columnIndex | ||
) | const |
Definition at line 674 of file RNTupleDescriptor.cxx.
ROOT::Experimental::DescriptorId_t ROOT::Experimental::RNTupleDescriptor::FindFieldId | ( | std::string_view | fieldName | ) | const |
Searches for a top-level field.
Definition at line 666 of file RNTupleDescriptor.cxx.
ROOT::Experimental::DescriptorId_t ROOT::Experimental::RNTupleDescriptor::FindFieldId | ( | std::string_view | fieldName, |
DescriptorId_t | parentId | ||
) | const |
Definition at line 649 of file RNTupleDescriptor.cxx.
std::unique_ptr< ROOT::Experimental::RNTupleModel > ROOT::Experimental::RNTupleDescriptor::GenerateModel | ( | ) | const |
Re-create the C++ model from the stored meta-data.
Definition at line 697 of file RNTupleDescriptor.cxx.
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Definition at line 337 of file RNTupleDescriptor.hxx.
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Definition at line 332 of file RNTupleDescriptor.hxx.
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Definition at line 329 of file RNTupleDescriptor.hxx.
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Definition at line 338 of file RNTupleDescriptor.hxx.
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Definition at line 336 of file RNTupleDescriptor.hxx.
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Definition at line 328 of file RNTupleDescriptor.hxx.
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Definition at line 343 of file RNTupleDescriptor.hxx.
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Definition at line 335 of file RNTupleDescriptor.hxx.
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Definition at line 347 of file RNTupleDescriptor.hxx.
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Definition at line 346 of file RNTupleDescriptor.hxx.
ROOT::Experimental::NTupleSize_t ROOT::Experimental::RNTupleDescriptor::GetNElements | ( | DescriptorId_t | columnId | ) | const |
Definition at line 638 of file RNTupleDescriptor.cxx.
ROOT::Experimental::NTupleSize_t ROOT::Experimental::RNTupleDescriptor::GetNEntries | ( | ) | const |
Definition at line 629 of file RNTupleDescriptor.cxx.
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Definition at line 345 of file RNTupleDescriptor.hxx.
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Definition at line 342 of file RNTupleDescriptor.hxx.
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Definition at line 339 of file RNTupleDescriptor.hxx.
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Definition at line 340 of file RNTupleDescriptor.hxx.
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Definition at line 341 of file RNTupleDescriptor.hxx.
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Given kNBytesPostscript bytes, extract the header and footer lengths in bytes.
Definition at line 617 of file RNTupleDescriptor.cxx.
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bool ROOT::Experimental::RNTupleDescriptor::operator== | ( | const RNTupleDescriptor & | other | ) | const |
Definition at line 517 of file RNTupleDescriptor.cxx.
void ROOT::Experimental::RNTupleDescriptor::PrintInfo | ( | std::ostream & | output | ) | const |
Definition at line 97 of file RNTupleDescriptorFmt.cxx.
std::uint32_t ROOT::Experimental::RNTupleDescriptor::SerializeFooter | ( | void * | buffer | ) | const |
Serializes cluster meta data. Returns the number of bytes and fills buffer if it is not nullptr.
Definition at line 569 of file RNTupleDescriptor.cxx.
std::uint32_t ROOT::Experimental::RNTupleDescriptor::SerializeHeader | ( | void * | buffer | ) | const |
We deliberately do not use ROOT's built-in serialization in order to allow for use of RNTuple's without libCore Serializes the global ntuple information as well as the column and field schemata Returns the number of bytes and fills buffer if it is not nullptr.
Definition at line 533 of file RNTupleDescriptor.cxx.
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Definition at line 273 of file RNTupleDescriptor.hxx.
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The origin of the data.
Definition at line 281 of file RNTupleDescriptor.hxx.
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May contain only a subset of all the available clusters, e.g.
the clusters of the current file from a chain of files
Definition at line 300 of file RNTupleDescriptor.hxx.
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Definition at line 297 of file RNTupleDescriptor.hxx.
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The current responsible for storing the data.
Definition at line 283 of file RNTupleDescriptor.hxx.
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Free text from the user.
Definition at line 279 of file RNTupleDescriptor.hxx.
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Definition at line 296 of file RNTupleDescriptor.hxx.
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Column sets that are created as derived sets from existing NTuples share the same group id.
NTuples in the same group have the same number of entries and are supposed to contain associated data.
Definition at line 294 of file RNTupleDescriptor.hxx.
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The ntuple name needs to be unique in a given storage location (file)
Definition at line 277 of file RNTupleDescriptor.hxx.
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Every NTuple gets a unique identifier.
Definition at line 291 of file RNTupleDescriptor.hxx.
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The time stamp of the ntuple data (immutable)
Definition at line 285 of file RNTupleDescriptor.hxx.
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The time stamp of writing the data to storage, which gets updated when re-written.
Definition at line 287 of file RNTupleDescriptor.hxx.
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The version evolves with the ntuple summary meta-data.
Definition at line 289 of file RNTupleDescriptor.hxx.
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staticconstexpr |
In order to handle changes to the serialization routine in future ntuple versions.
Definition at line 304 of file RNTupleDescriptor.hxx.
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Definition at line 305 of file RNTupleDescriptor.hxx.
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staticconstexpr |
The last few bytes after the footer store the length of footer and header.
Definition at line 309 of file RNTupleDescriptor.hxx.
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staticconstexpr |
The preamble is sufficient to get the length of the header.
Definition at line 307 of file RNTupleDescriptor.hxx.