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bucket_traverser.go
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bucket_traverser.go
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package engine
import "github.com/influxdb/influxdb/protocol"
// Traverses the buckets in either ascending or descending order. Each
// bucket have the form (C1, C2, time) where C1 and C2 are column
// values and time is the timestamp. The traverser applies the given
// function on all nodes with the timestamp in either ascending or
// descending order
type bucketTraverser struct {
trie *Trie // the trie we're going to traverse
last int64 // the last bucket's timestamp that we will visit
current int64 // the current timestamp
step int64 // the step (could be negative if the query is descending)
levels int // the number of levels in the trie
aggregators int // the number of aggregators that we have to run
asc bool // ascending or descending query
}
func newBucketTraverser(trie *Trie, levels, aggregators int, startBucket, endBucket, durationMicro int64, asc bool) *bucketTraverser {
bt := &bucketTraverser{
trie: trie,
levels: levels,
aggregators: aggregators,
last: startBucket,
current: endBucket,
step: -durationMicro,
asc: asc,
}
if !asc {
return bt
}
bt.last = endBucket
bt.current = startBucket
bt.step = durationMicro
return bt
}
func (bt *bucketTraverser) reachedEnd() bool {
if bt.asc {
return bt.current > bt.last
}
return bt.current < bt.last
}
func (bt *bucketTraverser) apply(f func(fv []*protocol.FieldValue, node *Node) error) error {
for !bt.reachedEnd() {
timestamp := &protocol.FieldValue{Int64Value: protocol.Int64(bt.current)}
defaultChildNode := &Node{states: make([]interface{}, bt.aggregators)}
err := bt.trie.TraverseLevel(bt.levels, func(v []*protocol.FieldValue, node *Node) error {
childNode := node.GetChildNode(timestamp)
if childNode == nil {
childNode = defaultChildNode
}
return f(append(v, timestamp), childNode)
})
if err != nil {
return err
}
bt.current += bt.step
}
return nil
}