/
iterator.go
136 lines (113 loc) · 3.6 KB
/
iterator.go
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// The MIT License
//
// Copyright (c) 2020 Temporal Technologies Inc. All rights reserved.
//
// Copyright (c) 2020 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package queues
import (
"fmt"
"go.temporal.io/server/common/collection"
"go.temporal.io/server/service/history/tasks"
)
type (
Iterator interface {
collection.Iterator[tasks.Task]
Range() Range
CanSplit(tasks.Key) bool
Split(key tasks.Key) (left Iterator, right Iterator)
CanMerge(Iterator) bool
Merge(Iterator) Iterator
Remaining() Iterator
}
paginationFnProvider func(Range) collection.PaginationFn[tasks.Task]
IteratorImpl struct {
paginationFnProvider paginationFnProvider
remainingRange Range
pagingIterator collection.Iterator[tasks.Task]
}
)
func NewIterator(
paginationFnProvider paginationFnProvider,
r Range,
) *IteratorImpl {
return &IteratorImpl{
paginationFnProvider: paginationFnProvider,
remainingRange: r,
// lazy initialized to prevent task pre-fetching on creating the iterator
pagingIterator: nil,
}
}
func (i *IteratorImpl) HasNext() bool {
if i.pagingIterator == nil {
i.pagingIterator = collection.NewPagingIterator(i.paginationFnProvider(i.remainingRange))
}
return i.pagingIterator.HasNext()
}
func (i *IteratorImpl) Next() (tasks.Task, error) {
if !i.HasNext() {
panic("Iterator encountered Next call when there is no next item")
}
task, err := i.pagingIterator.Next()
if err != nil {
return nil, err
}
i.remainingRange.InclusiveMin = task.GetKey().Next()
return task, nil
}
func (i *IteratorImpl) Range() Range {
return i.remainingRange
}
func (i *IteratorImpl) CanSplit(key tasks.Key) bool {
return i.remainingRange.CanSplit(key)
}
func (i *IteratorImpl) Split(key tasks.Key) (left Iterator, right Iterator) {
if !i.CanSplit(key) {
panic(fmt.Sprintf("Unable to split iterator with range %v at %v", i.remainingRange, key))
}
leftRange, rightRange := i.remainingRange.Split(key)
left = NewIterator(
i.paginationFnProvider,
leftRange,
)
right = NewIterator(
i.paginationFnProvider,
rightRange,
)
return left, right
}
func (i *IteratorImpl) CanMerge(iter Iterator) bool {
return i.remainingRange.CanMerge(iter.Range())
}
func (i *IteratorImpl) Merge(iter Iterator) Iterator {
if !i.CanMerge(iter) {
panic(fmt.Sprintf("Unable to merge iterator range %v with incoming iterator range %v", i.remainingRange, iter.Range()))
}
return NewIterator(
i.paginationFnProvider,
i.remainingRange.Merge(iter.Range()),
)
}
func (i *IteratorImpl) Remaining() Iterator {
return NewIterator(
i.paginationFnProvider,
i.remainingRange,
)
}