ROOT::Experimental::Internal::RWritePageMemoryManager Class Reference

Helper to maintain a memory budget for the write pages of a set of columns.

The memory manager keeps track of the sum of bytes used by the write pages of a set of columns. It will flush (and shrink) large pages of other columns on the attempt to expand a page.

Definition at line 212 of file RPageStorage.hxx.

Classes
struct	RColumnInfo

Public Member Functions
	RWritePageMemoryManager (std::size_t maxAllocatedBytes)
bool	TryUpdate (RColumn &column, std::size_t newWritePageSize)
	Try to register the new write page size for the given column.

Private Member Functions
bool	TryEvict (std::size_t targetAvailableSize, std::size_t pageSizeLimit)
	Flush columns in order of allocated write page size until the sum of all write page allocations leaves space for at least targetAvailableSize bytes.

Private Attributes
std::set< RColumnInfo, std::greater< RColumnInfo > >	fColumnsSortedByPageSize
	All columns that called ReservePage() (hence TryUpdate()) at least once, sorted by their current write page size from large to small.
std::size_t	fCurrentAllocatedBytes = 0
	Sum of all the write page sizes (their capacity) of the columns in fColumnsSortedByPageSize
std::size_t	fMaxAllocatedBytes = 0
	Maximum allowed value for fCurrentAllocatedBytes, set from RNTupleWriteOptions::fPageBufferBudget.

#include <ROOT/RPageStorage.hxx>

Constructor & Destructor Documentation

RWritePageMemoryManager()

ROOT::Experimental::Internal::RWritePageMemoryManager::RWritePageMemoryManager ( std::size_t  maxAllocatedBytes )

inlineexplicit

Definition at line 236 of file RPageStorage.hxx.

Member Function Documentation

TryEvict()

bool ROOT::Experimental::Internal::RWritePageMemoryManager::TryEvict ( std::size_t  targetAvailableSize, std::size_t  pageSizeLimit  )

private

Flush columns in order of allocated write page size until the sum of all write page allocations leaves space for at least targetAvailableSize bytes.

Only use columns with a write page size larger than pageSizeLimit.

Definition at line 582 of file RPageStorage.cxx.

TryUpdate()

bool ROOT::Experimental::Internal::RWritePageMemoryManager::TryUpdate	(	RColumn &	column,
		std::size_t	newWritePageSize
	)

Try to register the new write page size for the given column.

Flush large columns to make space, if necessary. If not enough space is available after all (sum of write pages would be larger than fMaxAllocatedBytes), return false.

Definition at line 616 of file RPageStorage.cxx.

Member Data Documentation

fColumnsSortedByPageSize

std::set<RColumnInfo, std::greater<RColumnInfo> > ROOT::Experimental::Internal::RWritePageMemoryManager::fColumnsSortedByPageSize

private

All columns that called ReservePage() (hence TryUpdate()) at least once, sorted by their current write page size from large to small.

Definition at line 228 of file RPageStorage.hxx.

fCurrentAllocatedBytes

std::size_t ROOT::Experimental::Internal::RWritePageMemoryManager::fCurrentAllocatedBytes = 0

private

Sum of all the write page sizes (their capacity) of the columns in fColumnsSortedByPageSize

Definition at line 223 of file RPageStorage.hxx.

fMaxAllocatedBytes

std::size_t ROOT::Experimental::Internal::RWritePageMemoryManager::fMaxAllocatedBytes = 0

private

Maximum allowed value for fCurrentAllocatedBytes, set from RNTupleWriteOptions::fPageBufferBudget.

Definition at line 225 of file RPageStorage.hxx.

Libraries for ROOT::Experimental::Internal::RWritePageMemoryManager:

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

• tree/ntuple/v7/inc/ROOT/RPageStorage.hxx
• tree/ntuple/v7/src/RPageStorage.cxx