allocator

Documentation

Index

• type AllocationBitmap
  • func NewAllocationMap(max int, rangeSpec string) *AllocationBitmap
  • func NewAllocationMapWithOffset(max int, rangeSpec string, offset int) *AllocationBitmap
  • func (r *AllocationBitmap) Allocate(offset int) (bool, error)
  • func (r *AllocationBitmap) AllocateNext() (int, bool, error)
  • func (r *AllocationBitmap) Destroy()
  • func (r *AllocationBitmap) ForEach(fn func(int))
  • func (r *AllocationBitmap) Free() int
  • func (r *AllocationBitmap) Has(offset int) bool
  • func (r *AllocationBitmap) Release(offset int) error
  • func (r *AllocationBitmap) Restore(rangeSpec string, data []byte) error
  • func (r *AllocationBitmap) Snapshot() (string, []byte)
• type AllocatorFactory
• type AllocatorWithOffsetFactory
• type Interface
• type Snapshottable

Types

type AllocationBitmap

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

AllocationBitmap is a contiguous block of resources that can be allocated atomically.

Each resource has an offset. The internal structure is a bitmap, with a bit for each offset.

If a resource is taken, the bit at that offset is set to one. r.count is always equal to the number of set bits and can be recalculated at any time by counting the set bits in r.allocated.

TODO: use RLE and compact the allocator to minimize space.

func NewAllocationMap

func NewAllocationMap(max int, rangeSpec string) *AllocationBitmap

NewAllocationMap creates an allocation bitmap using the random scan strategy.

func NewAllocationMapWithOffset

func NewAllocationMapWithOffset(max int, rangeSpec string, offset int) *AllocationBitmap

NewAllocationMapWithOffset creates an allocation bitmap using a random scan strategy that allows to pass an offset that divides the allocation bitmap in two blocks. The first block of values will not be used for random value assigned by the AllocateNext() method until the second block of values has been exhausted. The offset value must be always smaller than the bitmap size.

func (*AllocationBitmap) Allocate

func (r *AllocationBitmap) Allocate(offset int) (bool, error)

Allocate attempts to reserve the provided item. Returns true if it was allocated, false if it was already in use

func (*AllocationBitmap) AllocateNext

func (r *AllocationBitmap) AllocateNext() (int, bool, error)

AllocateNext reserves one of the items from the pool. (0, false, nil) may be returned if there are no items left.

func (*AllocationBitmap) Destroy

func (r *AllocationBitmap) Destroy()

Destroy cleans up everything on shutdown.

func (*AllocationBitmap) ForEach

func (r *AllocationBitmap) ForEach(fn func(int))

ForEach calls the provided function for each allocated bit. The AllocationBitmap may not be modified while this loop is running.

func (*AllocationBitmap) Free

func (r *AllocationBitmap) Free() int

Free returns the count of items left in the range.

func (*AllocationBitmap) Has

func (r *AllocationBitmap) Has(offset int) bool

Has returns true if the provided item is already allocated and a call to Allocate(offset) would fail.

func (*AllocationBitmap) Release

func (r *AllocationBitmap) Release(offset int) error

Release releases the item back to the pool. Releasing an unallocated item or an item out of the range is a no-op and returns no error.

func (*AllocationBitmap) Restore

func (r *AllocationBitmap) Restore(rangeSpec string, data []byte) error

Restore restores the pool to the previously captured state.

func (*AllocationBitmap) Snapshot

func (r *AllocationBitmap) Snapshot() (string, []byte)

Snapshot saves the current state of the pool.

type AllocatorFactory

type AllocatorFactory func(max int, rangeSpec string) (Interface, error)

type AllocatorWithOffsetFactory

type AllocatorWithOffsetFactory func(max int, rangeSpec string, offset int) (Interface, error)

type Interface

type Interface interface {
	Allocate(int) (bool, error)
	AllocateNext() (int, bool, error)
	Release(int) error
	ForEach(func(int))
	Has(int) bool
	Free() int

	// Destroy shuts down all internal structures.
	// Destroy needs to be implemented in thread-safe way and be prepared for being
	// called more than once.
	Destroy()
}

Interface manages the allocation of items out of a range. Interface should be threadsafe.

type Snapshottable

type Snapshottable interface {
	Interface
	Snapshot() (string, []byte)
	Restore(string, []byte) error
}

Snapshottable is an Interface that can be snapshotted and restored. Snapshottable should be threadsafe.