forked from m3db/m3
/
accounted_series_iter.go
89 lines (75 loc) · 2.9 KB
/
accounted_series_iter.go
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// Copyright (c) 2018 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 m3
import (
"github.com/m3db/m3/src/dbnode/encoding"
"github.com/m3db/m3/src/query/cost"
"github.com/uber-go/tally"
)
// AccountedSeriesIter wraps a series iterator to track and enforce limits on datapoint usage. Datapoint usage
// is tracked on each call to Next().
type AccountedSeriesIter struct {
encoding.SeriesIterator
scope tally.Scope
fetchedDps tally.Counter
enforcer cost.ChainedEnforcer
enforcerErr error
}
// NewAccountedSeriesIter constructs an AccountedSeriesIter which uses wrapped as its source.
func NewAccountedSeriesIter(wrapped encoding.SeriesIterator, enforcer cost.ChainedEnforcer, scope tally.Scope) *AccountedSeriesIter {
return &AccountedSeriesIter{
SeriesIterator: wrapped,
enforcer: enforcer,
scope: scope,
fetchedDps: scope.Tagged(map[string]string{"type": "fetched"}).Counter("datapoints"),
}
}
// Err returns the underlying iterator's error if present, or any limit exceeded error.
func (as *AccountedSeriesIter) Err() error {
if err := as.SeriesIterator.Err(); err != nil {
return err
}
return as.enforcerErr
}
// Next advances the underlying iterator and adds to the datapoint count. If that count exceeds the limit, it will
// set this iterator's error.
func (as *AccountedSeriesIter) Next() bool {
if as.enforcerErr != nil {
return false
}
hasNext := as.SeriesIterator.Next()
if !hasNext {
// nothing left; don't inform the enforcer
return false
}
as.fetchedDps.Inc(1)
// we actually advanced the iterator; inform the enforcer
r := as.enforcer.Add(1.0)
if err := r.Error; err != nil {
as.enforcerErr = err
return false
}
return hasNext
}
// Close closes the underlying iterator, and marks datapoints as released to our enforcer.
func (as *AccountedSeriesIter) Close() {
as.SeriesIterator.Close()
as.enforcer.Close()
}