github.com/m3db/m3@v1.5.0/src/cluster/placement/selector/common.go (about)

     1  // Copyright (c) 2017 Uber Technologies, Inc.
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to deal
     5  // in the Software without restriction, including without limitation the rights
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     7  // copies of the Software, and to permit persons to whom the Software is
     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  package selector
    22  
    23  import (
    24  	"errors"
    25  
    26  	"github.com/m3db/m3/src/cluster/placement"
    27  )
    28  
    29  var (
    30  	errNoValidCandidateInstance = errors.New("no new instances found in the valid zone")
    31  )
    32  
    33  // getValidCandidates finds the instances that are not already in
    34  // the placement and in the valid zone.
    35  func getValidCandidates(
    36  	p placement.Placement,
    37  	candidates []placement.Instance,
    38  	opts placement.Options,
    39  ) ([]placement.Instance, error) {
    40  	var instances = make([]placement.Instance, 0, len(candidates))
    41  	for _, instance := range candidates {
    42  		instanceInPlacement, exist := p.Instance(instance.ID())
    43  		if !exist {
    44  			instances = append(instances, instance)
    45  			continue
    46  		}
    47  		if instanceInPlacement.IsLeaving() {
    48  			instances = append(instances, instanceInPlacement)
    49  		}
    50  	}
    51  
    52  	instances = filterZones(p, instances, opts)
    53  	if len(instances) == 0 {
    54  		return nil, errNoValidCandidateInstance
    55  	}
    56  
    57  	return instances, nil
    58  }
    59  
    60  func filterZones(
    61  	p placement.Placement,
    62  	candidates []placement.Instance,
    63  	opts placement.Options,
    64  ) []placement.Instance {
    65  	if len(candidates) == 0 {
    66  		return []placement.Instance{}
    67  	}
    68  
    69  	var validZone string
    70  	if opts != nil {
    71  		validZone = opts.ValidZone()
    72  		if opts.AllowAllZones() {
    73  			return candidates
    74  		}
    75  	}
    76  	if validZone == "" && len(p.Instances()) > 0 {
    77  		validZone = p.Instances()[0].Zone()
    78  	}
    79  
    80  	validInstances := make([]placement.Instance, 0, len(candidates))
    81  	for _, instance := range candidates {
    82  		if validZone == instance.Zone() {
    83  			validInstances = append(validInstances, instance)
    84  		}
    85  	}
    86  	return validInstances
    87  }