bitmap

Documentation

Index

• type AllocationBitmap
  • func NewAllocationMap(max int, rangeSpec string) *AllocationBitmap
  • func NewContiguousAllocationMap(max int, rangeSpec string) *AllocationBitmap
  • func NewRoundRobinAllocationMap(max int, rangeSpec string) *AllocationBitmap
  • func (r *AllocationBitmap) Allocate(offset int) (bool, error)
  • func (r *AllocationBitmap) AllocateNext() (int, bool, error)
  • 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)
  • func (r *AllocationBitmap) Restore(rangeSpec string, data []byte) error
  • func (r *AllocationBitmap) Snapshot() (string, []byte)
• type AllocatorFactory
• 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 NewContiguousAllocationMap

func NewContiguousAllocationMap(max int, rangeSpec string) *AllocationBitmap

NewContiguousAllocationMap creates an allocation bitmap using the contiguous scan strategy.

func NewRoundRobinAllocationMap

func NewRoundRobinAllocationMap(max int, rangeSpec string) *AllocationBitmap

NewRoundRobinAllocationMap creates an allocation bitmap using the round-robin scan strategy.

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) 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)

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 Interface

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

	// For testing
	Has(int) bool

	// For testing
	Free() int
}

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.