bufferpool

package
v3.31.0 Latest Latest
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 Go to latest Published: Feb 1, 2023 License: Apache-2.0, Apache-2.0 Imports: 6 Imported by: 0

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Index

Constants

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const INVALID_PAGE int = -1
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const PAGE_FREE_SPACE_OFFSET = 10 // offset 10, length 2, end 12
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const PAGE_LOCAL_DEPTH_OFFSET = 8 // offset 8, length 2, end 10
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const PAGE_NEXT_POINTER_OFFSET = 16 // offset 16, length 4, end 20
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const PAGE_NUMBER_OFFSET = 0 // offset 0, length 4, end 4
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const PAGE_PREV_POINTER_OFFSET = 12 // offset 12, length 4, end 16
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const PAGE_SIZE int = 8192
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const PAGE_SLOTS_START_OFFSET = 20 // offset 20
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const PAGE_SLOT_COUNT_OFFSET = 6 // offset 6, length 2, end 8
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const PAGE_SLOT_LENGTH = 4

page slots 

key offset int16    	//offset 0, length 2, end 2
value offset int16	    //offset 2, length 2, end 4
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const PAGE_TYPE_BTREE_INTERNAL = 10
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const PAGE_TYPE_BTREE_LEAF = 11
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const PAGE_TYPE_HASH_TABLE = 12
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const PAGE_TYPE_OFFSET = 4 // offset 4, length 2, end 6

Variables

This section is empty.

Functions

This section is empty.

Types

type BufferPool 

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

BufferPool represents a buffer pool of pages

func NewBufferPool 

func NewBufferPool(maxSize int, diskManager DiskManager) *BufferPool

NewBufferPool returns a buffer pool

func (*BufferPool) Close 

func (b *BufferPool) Close()

Close closes the buffer pool

func (*BufferPool) DeletePage 

func (b *BufferPool) DeletePage(pageID PageID) error

DeletePage deletes a page from the buffer pool

func (*BufferPool) Dump 

func (b *BufferPool) Dump()

Dumps all the pages in the buffer pool

func (*BufferPool) FetchPage 

func (b *BufferPool) FetchPage(pageID PageID) (*Page, error)

FetchPage fetches the requested page from the buffer pool.

func (*BufferPool) FlushAllpages 

func (b *BufferPool) FlushAllpages()

FlushAllpages flushes all the pages in the buffer pool to disk Yeah, never call this unless you know what you are doing

func (*BufferPool) FlushPage 

func (b *BufferPool) FlushPage(pageID PageID) bool

FlushPage Flushes the target page to disk

func (*BufferPool) NewPage 

func (b *BufferPool) NewPage() (*Page, error)

NewPage allocates a new page in the buffer pool with the disk manager help

func (*BufferPool) OnDiskSize 

func (b *BufferPool) OnDiskSize() int64

OnDiskSize exposes the on disk size of the backing store behind this buffer pool

func (*BufferPool) ScratchPage 

func (b *BufferPool) ScratchPage() *Page

ScratchPage returns a page outside the buffer pool - do not use if you intend the page to be in the buffer pool (use NewPage() for that) ScratchPage is intended to be used in cases where you need the Page primitives and will copy the scratch page back over a real page later

func (*BufferPool) UnpinPage 

func (b *BufferPool) UnpinPage(pageID PageID) error

UnpinPage unpins the target page from the buffer pool

type ClockReplacer 

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

ClockReplacer implements a clock replacer algorithm

func NewClockReplacer 

func NewClockReplacer(poolSize int) *ClockReplacer

NewClockReplacer instantiates a new clock replacer

func (*ClockReplacer) Pin 

func (c *ClockReplacer) Pin(id FrameID)

Pin pins a frame, indicating that it should not be victimized until it is unpinned

func (*ClockReplacer) Size 

func (c *ClockReplacer) Size() int

Size returns the size of the clock

func (*ClockReplacer) Unpin 

func (c *ClockReplacer) Unpin(id FrameID)

Unpin unpins a frame, indicating that it can now be victimized

func (*ClockReplacer) Victim 

func (c *ClockReplacer) Victim() (FrameID, error)

Victim removes the victim frame as defined by the replacement policy

type DiskManager 

type DiskManager interface {
	// reads a page from the disk
	ReadPage(PageID) (*Page, error)
	// writes a page to the disk
	WritePage(*Page) error

	// allocates a page
	AllocatePage() (PageID, error)

	// deallocates a page
	DeallocatePage(PageID) error

	// returns on disk file size
	FileSize() int64

	// closes and does any clean up
	Close()
}

DiskManager is responsible for interacting with disk

type FrameID 

type FrameID int

FrameID is the type for frame id

type InMemDiskSpillingDiskManager 

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

InMemDiskSpillingDiskManager is a memory implementation for a DiskManager interface that can spill to disk when a threshold is reached

func NewInMemDiskSpillingDiskManager 

func NewInMemDiskSpillingDiskManager(thresholdPages int) *InMemDiskSpillingDiskManager

NewInMemDiskSpillingDiskManager returns a in-memory version of disk manager

func (*InMemDiskSpillingDiskManager) AllocatePage 

func (d *InMemDiskSpillingDiskManager) AllocatePage() (PageID, error)

AllocatePage allocates a page and returns the page number

func (*InMemDiskSpillingDiskManager) Close 

func (d *InMemDiskSpillingDiskManager) Close()

func (*InMemDiskSpillingDiskManager) DeallocatePage 

func (d *InMemDiskSpillingDiskManager) DeallocatePage(pageID PageID) error

DeallocatePage removes page from disk

func (*InMemDiskSpillingDiskManager) FileSize 

func (d *InMemDiskSpillingDiskManager) FileSize() int64

func (*InMemDiskSpillingDiskManager) ReadPage 

func (d *InMemDiskSpillingDiskManager) ReadPage(pageID PageID) (*Page, error)

ReadPage reads a page from pages

func (*InMemDiskSpillingDiskManager) WritePage 

func (d *InMemDiskSpillingDiskManager) WritePage(page *Page) error

WritePage writes a page in memory to pages

type Page 

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

Page represents a page on disk

func (*Page) DecPinCount 

func (p *Page) DecPinCount()

func (*Page) Dump 

func (pg *Page) Dump(label string)

func (*Page) FreeSpace 

func (p *Page) FreeSpace() int16

func (*Page) ID 

func (p *Page) ID() PageID

func (*Page) PinCount 

func (p *Page) PinCount() int

func (*Page) ReadChunk 

func (p *Page) ReadChunk(offset int16) PageChunk

func (*Page) ReadFreeSpaceOffset 

func (p *Page) ReadFreeSpaceOffset() int16

func (*Page) ReadLocalDepth 

func (p *Page) ReadLocalDepth() int16

func (*Page) ReadNextPointer 

func (p *Page) ReadNextPointer() int

func (*Page) ReadPageNumber 

func (p *Page) ReadPageNumber() int

func (*Page) ReadPageType 

func (p *Page) ReadPageType() int16

func (*Page) ReadPrevPointer 

func (p *Page) ReadPrevPointer() int

func (*Page) ReadSlot 

func (p *Page) ReadSlot(slot int16) PageSlot

func (*Page) ReadSlotCount 

func (p *Page) ReadSlotCount() int16

func (*Page) WriteChunk 

func (p *Page) WriteChunk(offset int16, chunk PageChunk)

func (*Page) WriteFreeSpaceOffset 

func (p *Page) WriteFreeSpaceOffset(offset int16)

func (*Page) WriteKeyValueInSlot 

func (p *Page) WriteKeyValueInSlot(slotNumber int16, key []byte, value []byte) error

func (*Page) WriteLocalDepth 

func (p *Page) WriteLocalDepth(localDepth int16)

func (*Page) WriteNextPointer 

func (p *Page) WriteNextPointer(nextPointer int32)

func (*Page) WritePage 

func (p *Page) WritePage(page *Page)

func (*Page) WritePageNumber 

func (p *Page) WritePageNumber(pageNumber int32)

func (*Page) WritePageType 

func (p *Page) WritePageType(pageType int16)

func (*Page) WritePrevPointer 

func (p *Page) WritePrevPointer(prevPointer int32)

func (*Page) WriteSlot 

func (p *Page) WriteSlot(slot int16, value PageSlot)

func (*Page) WriteSlotCount 

func (p *Page) WriteSlotCount(slotCount int16)

type PageChunk 

type PageChunk struct {
	KeyLength int16
	KeyBytes  []byte
	// TODO(pok) ValueBytes can be up to int32 long
	// this requires an overflow page mechanism, that is not implemented
	// yet, so be aware of this when storing stuff...
	ValueLength int32
	ValueBytes  []byte
}

func (*PageChunk) ComputeKeyOffset 

func (pc *PageChunk) ComputeKeyOffset(pageOffset int) int

func (*PageChunk) ComputeValueOffset 

func (pc *PageChunk) ComputeValueOffset(pageOffset int) int

func (*PageChunk) Length 

func (pc *PageChunk) Length() int

type PageID 

type PageID int

PageID is the type for page id

type PageSlot 

type PageSlot struct {
	KeyOffset   int16
	ValueOffset int16
}

func (*PageSlot) KeyAsInt 

func (s *PageSlot) KeyAsInt(page *Page) int32

func (*PageSlot) KeyBytes 

func (s *PageSlot) KeyBytes(page *Page) []byte

func (*PageSlot) ValueAsPagePointer 

func (s *PageSlot) ValueAsPagePointer(page *Page) int32

func (*PageSlot) ValueBytes 

func (s *PageSlot) ValueBytes(page *Page) []byte

type PageSlotIterator 

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

func NewPageSlotIterator 

func NewPageSlotIterator(page *Page, fromSlot int16) *PageSlotIterator

func (*PageSlotIterator) Cursor 

func (i *PageSlotIterator) Cursor() int16

func (*PageSlotIterator) Next 

func (i *PageSlotIterator) Next() *PageSlot

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