blob: 70e2775455bfa709bd3406e19ab864af5b949de9 [file] [log] [blame]
// Copyright 2018 The LUCI Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package policy
import (
"math"
"go.chromium.org/luci/common/errors"
"go.chromium.org/luci/scheduler/appengine/internal"
)
// LogarithmicBatchingPolicy instantiates new LOGARITHMIC_BATCHING policy
// function.
//
// It takes all pending triggers and collapses log_k N of them into one new
// invocation, deriving its properties from the most recent trigger alone.
func LogarithmicBatchingPolicy(maxConcurrentInvs, maxBatchSize int, logBase float64) (Func, error) {
// We use 1.0001 to ensure that operation below returns a value small enough
// to fit into int and to avoid numerical stability issues resulting from
// very small values being approximated as 0 and resulting in
// division-by-zero errors.
if logBase < 1.0001 {
return nil, errors.Reason("log_base should be more or equal than 1.0001").Err()
}
log := math.Log(logBase)
return basePolicy(maxConcurrentInvs, maxBatchSize, func(triggers []*internal.Trigger) int {
return int(math.Max(math.Log(float64(len(triggers)))/log, 1.0))
})
}