220 lines
7.0 KiB
Go
220 lines
7.0 KiB
Go
// This file is part of MinIO Console Server
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// Copyright (c) 2020 MinIO, Inc.
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package utils
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import (
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"errors"
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"fmt"
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"sort"
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"github.com/minio/minio/pkg/ellipses"
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)
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// This file implements and supports ellipses pattern for
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// `minio server` command line arguments.
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// Supported set sizes this is used to find the optimal
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// single set size.
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var setSizes = []uint64{4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}
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// getDivisibleSize - returns a greatest common divisor of
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// all the ellipses sizes.
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func getDivisibleSize(totalSizes []uint64) (result uint64) {
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gcd := func(x, y uint64) uint64 {
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for y != 0 {
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x, y = y, x%y
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}
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return x
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}
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result = totalSizes[0]
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for i := 1; i < len(totalSizes); i++ {
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result = gcd(result, totalSizes[i])
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}
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return result
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}
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// isValidSetSize - checks whether given count is a valid set size for erasure coding.
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var isValidSetSize = func(count uint64) bool {
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return (count >= setSizes[0] && count <= setSizes[len(setSizes)-1])
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}
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// possibleSetCountsWithSymmetry returns symmetrical setCounts based on the
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// input argument patterns, the symmetry calculation is to ensure that
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// we also use uniform number of drives common across all ellipses patterns.
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func possibleSetCountsWithSymmetry(setCounts []uint64, argPatterns []ellipses.ArgPattern) []uint64 {
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var newSetCounts = make(map[uint64]struct{})
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for _, ss := range setCounts {
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var symmetry bool
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for _, argPattern := range argPatterns {
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for _, p := range argPattern {
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if uint64(len(p.Seq)) > ss {
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symmetry = uint64(len(p.Seq))%ss == 0
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} else {
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symmetry = ss%uint64(len(p.Seq)) == 0
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}
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}
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}
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// With no arg patterns, it is expected that user knows
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// the right symmetry, so either ellipses patterns are
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// provided (recommended) or no ellipses patterns.
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if _, ok := newSetCounts[ss]; !ok && (symmetry || argPatterns == nil) {
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newSetCounts[ss] = struct{}{}
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}
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}
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setCounts = []uint64{}
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for setCount := range newSetCounts {
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setCounts = append(setCounts, setCount)
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}
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// Not necessarily needed but it ensures to the readers
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// eyes that we prefer a sorted setCount slice for the
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// subsequent function to figure out the right common
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// divisor, it avoids loops.
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sort.Slice(setCounts, func(i, j int) bool {
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return setCounts[i] < setCounts[j]
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})
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return setCounts
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}
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func commonSetDriveCount(divisibleSize uint64, setCounts []uint64) (setSize uint64) {
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// prefers setCounts to be sorted for optimal behavior.
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if divisibleSize < setCounts[len(setCounts)-1] {
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return divisibleSize
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}
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// Figure out largest value of total_drives_in_erasure_set which results
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// in least number of total_drives/total_drives_erasure_set ratio.
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prevD := divisibleSize / setCounts[0]
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for _, cnt := range setCounts {
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if divisibleSize%cnt == 0 {
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d := divisibleSize / cnt
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if d <= prevD {
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prevD = d
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setSize = cnt
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}
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}
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}
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return setSize
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}
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// getSetIndexes returns list of indexes which provides the set size
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// on each index, this function also determines the final set size
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// The final set size has the affinity towards choosing smaller
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// indexes (total sets)
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func getSetIndexes(args []string, totalSizes []uint64, argPatterns []ellipses.ArgPattern) (setIndexes [][]uint64, err error) {
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if len(totalSizes) == 0 || len(args) == 0 {
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return nil, errors.New("invalid argument")
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}
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setIndexes = make([][]uint64, len(totalSizes))
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for _, totalSize := range totalSizes {
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// Check if totalSize has minimum range upto setSize
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if totalSize < setSizes[0] {
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return nil, fmt.Errorf("incorrect number of endpoints provided %s", args)
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}
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}
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commonSize := getDivisibleSize(totalSizes)
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possibleSetCounts := func(setSize uint64) (ss []uint64) {
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for _, s := range setSizes {
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if setSize%s == 0 {
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ss = append(ss, s)
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}
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}
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return ss
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}
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setCounts := possibleSetCounts(commonSize)
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if len(setCounts) == 0 {
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err = fmt.Errorf("incorrect number of endpoints provided %s, number of disks %d is not divisible by any supported erasure set sizes %d", args, commonSize, setSizes)
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return nil, err
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}
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// Returns possible set counts with symmetry.
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setCounts = possibleSetCountsWithSymmetry(setCounts, argPatterns)
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if len(setCounts) == 0 {
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err = fmt.Errorf("no symmetric distribution detected with input endpoints provided %s, disks %d cannot be spread symmetrically by any supported erasure set sizes %d", args, commonSize, setSizes)
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return nil, err
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}
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// Final set size with all the symmetry accounted for.
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setSize := commonSetDriveCount(commonSize, setCounts)
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// Check whether setSize is with the supported range.
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if !isValidSetSize(setSize) {
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err = fmt.Errorf("incorrect number of endpoints provided %s, number of disks %d is not divisible by any supported erasure set sizes %d", args, commonSize, setSizes)
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return nil, err
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}
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for i := range totalSizes {
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for j := uint64(0); j < totalSizes[i]/setSize; j++ {
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setIndexes[i] = append(setIndexes[i], setSize)
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}
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}
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return setIndexes, nil
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}
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// Return the total size for each argument patterns.
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func getTotalSizes(argPatterns []ellipses.ArgPattern) []uint64 {
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var totalSizes []uint64
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for _, argPattern := range argPatterns {
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var totalSize uint64 = 1
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for _, p := range argPattern {
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totalSize = totalSize * uint64(len(p.Seq))
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}
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totalSizes = append(totalSizes, totalSize)
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}
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return totalSizes
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}
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// PossibleParityValues returns possible parities for input args,
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// parties are calculated in uniform manner for one zone or
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// multiple zones, ensuring that parities returned are common
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// and applicable across all zones.
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func PossibleParityValues(args ...string) ([]string, error) {
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setIndexes, err := parseEndpointSet(args...)
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if err != nil {
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return nil, err
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}
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maximumParity := setIndexes[0][0] / 2
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var parities []string
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for maximumParity >= 2 {
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parities = append(parities, fmt.Sprintf("EC:%d", maximumParity))
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maximumParity--
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}
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return parities, nil
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}
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// Parses all arguments and returns an endpointSet which is a collection
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// of endpoints following the ellipses pattern, this is what is used
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// by the object layer for initializing itself.
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func parseEndpointSet(args ...string) (setIndexes [][]uint64, err error) {
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var argPatterns = make([]ellipses.ArgPattern, len(args))
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for i, arg := range args {
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patterns, err := ellipses.FindEllipsesPatterns(arg)
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if err != nil {
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return nil, err
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}
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argPatterns[i] = patterns
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}
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return getSetIndexes(args, getTotalSizes(argPatterns), argPatterns)
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}
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