open-nomad/lib/delay_heap.go
2018-03-14 16:10:32 -05:00

168 lines
4 KiB
Go

package lib
import (
"container/heap"
"fmt"
"time"
"github.com/hashicorp/nomad/nomad/structs"
)
// DelayHeap wraps a heap and gives operations other than Push/Pop.
// The inner heap is sorted by the time in the WaitUntil field of delayHeapNode
type DelayHeap struct {
index map[structs.NamespacedID]*delayHeapNode
heap delayedHeapImp
}
// HeapNode is an interface type implemented by objects stored in the DelayHeap
type HeapNode interface {
Data() interface{} // The data object
ID() string // ID of the object, used in conjunction with namespace for deduplication
Namespace() string // Namespace of the object, can be empty
}
// delayHeapNode encapsulates the node stored in DelayHeap
// WaitUntil is used as the sorting criteria
type delayHeapNode struct {
// Node is the data object stored in the delay heap
Node HeapNode
// WaitUntil is the time delay associated with the node
// Objects in the heap are sorted by WaitUntil
WaitUntil time.Time
index int
}
type delayedHeapImp []*delayHeapNode
func (h delayedHeapImp) Len() int {
return len(h)
}
func (h delayedHeapImp) Less(i, j int) bool {
// Two zero times should return false.
// Otherwise, zero is "greater" than any other time.
// (To sort it at the end of the list.)
// Sort such that zero times are at the end of the list.
iZero, jZero := h[i].WaitUntil.IsZero(), h[j].WaitUntil.IsZero()
if iZero && jZero {
return false
} else if iZero {
return false
} else if jZero {
return true
}
return h[i].WaitUntil.Before(h[j].WaitUntil)
}
func (h delayedHeapImp) Swap(i, j int) {
h[i], h[j] = h[j], h[i]
h[i].index = i
h[j].index = j
}
func (h *delayedHeapImp) Push(x interface{}) {
node := x.(*delayHeapNode)
n := len(*h)
node.index = n
*h = append(*h, node)
}
func (h *delayedHeapImp) Pop() interface{} {
old := *h
n := len(old)
node := old[n-1]
node.index = -1 // for safety
*h = old[0 : n-1]
return node
}
func NewDelayHeap() *DelayHeap {
return &DelayHeap{
index: make(map[structs.NamespacedID]*delayHeapNode),
heap: make(delayedHeapImp, 0),
}
}
func (p *DelayHeap) Push(dataNode HeapNode, next time.Time) error {
tuple := structs.NamespacedID{
ID: dataNode.ID(),
Namespace: dataNode.Namespace(),
}
if _, ok := p.index[tuple]; ok {
return fmt.Errorf("node %q (%s) already exists", dataNode.ID(), dataNode.Namespace())
}
delayHeapNode := &delayHeapNode{dataNode, next, 0}
p.index[tuple] = delayHeapNode
heap.Push(&p.heap, delayHeapNode)
return nil
}
func (p *DelayHeap) Pop() *delayHeapNode {
if len(p.heap) == 0 {
return nil
}
delayHeapNode := heap.Pop(&p.heap).(*delayHeapNode)
tuple := structs.NamespacedID{
ID: delayHeapNode.Node.ID(),
Namespace: delayHeapNode.Node.Namespace(),
}
delete(p.index, tuple)
return delayHeapNode
}
func (p *DelayHeap) Peek() *delayHeapNode {
if len(p.heap) == 0 {
return nil
}
return p.heap[0]
}
func (p *DelayHeap) Contains(heapNode HeapNode) bool {
tuple := structs.NamespacedID{
ID: heapNode.ID(),
Namespace: heapNode.Namespace(),
}
_, ok := p.index[tuple]
return ok
}
func (p *DelayHeap) Update(heapNode HeapNode, waitUntil time.Time) error {
tuple := structs.NamespacedID{
ID: heapNode.ID(),
Namespace: heapNode.Namespace(),
}
if existingHeapNode, ok := p.index[tuple]; ok {
// Need to update the job as well because its spec can change.
existingHeapNode.Node = heapNode
existingHeapNode.WaitUntil = waitUntil
heap.Fix(&p.heap, existingHeapNode.index)
return nil
}
return fmt.Errorf("heap doesn't contain object with ID %q (%s)", heapNode.ID(), heapNode.Namespace())
}
func (p *DelayHeap) Remove(heapNode HeapNode) error {
tuple := structs.NamespacedID{
ID: heapNode.ID(),
Namespace: heapNode.Namespace(),
}
if node, ok := p.index[tuple]; ok {
heap.Remove(&p.heap, node.index)
delete(p.index, tuple)
return nil
}
return fmt.Errorf("heap doesn't contain object with ID %q (%s)", heapNode.ID(), heapNode.Namespace())
}
func (p *DelayHeap) Length() int {
return len(p.heap)
}