pager

package
v0.1.0 Latest Latest
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 Go to latest Published: Jan 23, 2026 License: MIT Imports: 7 Imported by: 0

Documentation

Index

Constants

This section is empty.

Variables

View Source 
var (
	ErrPageOutOfBounds = errors.New("page index out of bounds") // Added declaration
	ErrFileSize        = errors.New("file size is not a multiple of page size")
	ErrReadOnly        = errors.New("pager is read-only")
)

Functions

This section is empty.

Types

type Pager 

type Pager struct {
	// contains filtered or unexported fields
}

Pager manages the index.db file using chunked mmap.

func Open 

func Open(path string, chunkSize int64) (*Pager, error)

Open opens the pager at the given path. If the file doesn't exist, it creates it. chunkSize determines the size of each mmap region.

func OpenReadOnly 

func OpenReadOnly(path string, chunkSize int64) (*Pager, error)

OpenReadOnly opens an existing pager at path without modifying the underlying file.

The returned pager does not support Alloc/GetForWrite/Write/Sync.

func (*Pager) Alloc 

func (p *Pager) Alloc(count int) (uint64, error)

Alloc allocates `count` new pages and returns the ID of the first one. It grows the file if necessary.

func (*Pager) Close 

func (p *Pager) Close() error

Close closes the pager and unmaps memory.

func (*Pager) Get 

func (p *Pager) Get(pageID uint64) ([]byte, error)

Get returns the byte slice for the given page ID. CAUTION: The returned slice points directly to mmapped memory. Do not hold references to it after closing the pager.

func (*Pager) GetForWrite 

func (p *Pager) GetForWrite(pageID uint64) ([]byte, error)

GetForWrite returns the byte slice for the given page ID and marks the chunk dirty.

func (*Pager) IsVerified 

func (p *Pager) IsVerified(pageID uint64) bool

IsVerified returns true if the page has passed CRC verification. Thread-safe (protected by p.mu in caller, or we can add internal locking if needed, but Pager methods usually hold lock). Currently Pager.Get holds RLock.

func (*Pager) MarkUnverified 

func (p *Pager) MarkUnverified(pageID uint64)

MarkUnverified marks a page as unverified (dirty/reused).

func (*Pager) MarkVerified 

func (p *Pager) MarkVerified(pageID uint64)

MarkVerified marks a page as verified.

func (*Pager) PageCount 

func (p *Pager) PageCount() uint64

PageCount returns the current logical number of pages.

func (*Pager) ReadPage 

func (p *Pager) ReadPage(pageID uint64) ([]byte, error)

ReadPage returns a copy of the page data. Safe for concurrent use including checksum verification.

func (*Pager) SetPageCount 

func (p *Pager) SetPageCount(count uint64)

SetPageCount updates the logical page count. Should be called by the DB layer after recovery.

func (*Pager) SetVerifyOnRead 

func (p *Pager) SetVerifyOnRead(always bool)

SetVerifyOnRead enables or disables checksum verification on every read.

func (*Pager) Sync 

func (p *Pager) Sync() error

Sync msyncs the memory maps to disk.

func (*Pager) Truncate 

func (p *Pager) Truncate(targetPages uint64) error

Truncate resizes the file to the specified number of pages. Safety: Shrinking is forbidden. Only growing is allowed.

func (*Pager) VerifyOnRead 

func (p *Pager) VerifyOnRead() bool

VerifyOnRead reports whether checksum verification should happen on every read.

func (*Pager) Write 

func (p *Pager) Write(pageID uint64, data []byte) error

Write copies data into the page. The data slice must be exactly PageSize bytes (or less, but we usually write full pages).

Source Files

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