githaven-fork/vendor/github.com/blevesearch/zap/v15/chunk.go
6543 12a1f914f4
Vendor Update Go Libs (#13166)
* update github.com/alecthomas/chroma v0.8.0 -> v0.8.1

* github.com/blevesearch/bleve v1.0.10 -> v1.0.12

* editorconfig-core-go v2.1.1 -> v2.3.7

* github.com/gliderlabs/ssh v0.2.2 -> v0.3.1

* migrate editorconfig.ParseBytes to Parse

* github.com/shurcooL/vfsgen to 0d455de96546

* github.com/go-git/go-git/v5 v5.1.0 -> v5.2.0

* github.com/google/uuid v1.1.1 -> v1.1.2

* github.com/huandu/xstrings v1.3.0 -> v1.3.2

* github.com/klauspost/compress v1.10.11 -> v1.11.1

* github.com/markbates/goth v1.61.2 -> v1.65.0

* github.com/mattn/go-sqlite3 v1.14.0 -> v1.14.4

* github.com/mholt/archiver v3.3.0 -> v3.3.2

* github.com/microcosm-cc/bluemonday 4f7140c49acb -> v1.0.4

* github.com/minio/minio-go v7.0.4 -> v7.0.5

* github.com/olivere/elastic v7.0.9 -> v7.0.20

* github.com/urfave/cli v1.20.0 -> v1.22.4

* github.com/prometheus/client_golang v1.1.0 -> v1.8.0

* github.com/xanzy/go-gitlab v0.37.0 -> v0.38.1

* mvdan.cc/xurls v2.1.0 -> v2.2.0

Co-authored-by: Lauris BH <lauris@nix.lv>
2020-10-16 01:06:27 -04:00

68 lines
2.5 KiB
Go
Vendored

// Copyright (c) 2019 Couchbase, Inc.
//
// 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 zap
import (
"fmt"
)
// LegacyChunkMode was the original chunk mode (always chunk size 1024)
// this mode is still used for chunking doc values.
var LegacyChunkMode uint32 = 1024
// DefaultChunkMode is the most recent improvement to chunking and should
// be used by default.
var DefaultChunkMode uint32 = 1026
func getChunkSize(chunkMode uint32, cardinality uint64, maxDocs uint64) (uint64, error) {
switch {
// any chunkMode <= 1024 will always chunk with chunkSize=chunkMode
case chunkMode <= 1024:
// legacy chunk size
return uint64(chunkMode), nil
case chunkMode == 1025:
// attempt at simple improvement
// theory - the point of chunking is to put a bound on the maximum number of
// calls to Next() needed to find a random document. ie, you should be able
// to do one jump to the correct chunk, and then walk through at most
// chunk-size items
// previously 1024 was chosen as the chunk size, but this is particularly
// wasteful for low cardinality terms. the observation is that if there
// are less than 1024 items, why not put them all in one chunk,
// this way you'll still achieve the same goal of visiting at most
// chunk-size items.
// no attempt is made to tweak any other case
if cardinality <= 1024 {
return maxDocs, nil
}
return 1024, nil
case chunkMode == 1026:
// improve upon the ideas tested in chunkMode 1025
// the observation that the fewest number of dense chunks is the most
// desirable layout, given the built-in assumptions of chunking
// (that we want to put an upper-bound on the number of items you must
// walk over without skipping, currently tuned to 1024)
//
// 1. compute the number of chunks needed (max 1024/chunk)
// 2. convert to chunkSize, dividing into maxDocs
numChunks := (cardinality / 1024) + 1
chunkSize := maxDocs / numChunks
return chunkSize, nil
}
return 0, fmt.Errorf("unknown chunk mode %d", chunkMode)
}