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

     1  // Copyright (c) 2016 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 planner
    22  
    23  import (
    24  	"sort"
    25  
    26  	"github.com/m3db/m3/src/cluster/placement"
    27  )
    28  
    29  // shardAwareDeploymentPlanner plans the deployment so that as many instances can be deployed
    30  // at the same time without making more than 1 replica of any shard unavailable
    31  type shardAwareDeploymentPlanner struct {
    32  	options placement.DeploymentOptions
    33  }
    34  
    35  // NewShardAwareDeploymentPlanner returns a deployment planner
    36  func NewShardAwareDeploymentPlanner(options placement.DeploymentOptions) placement.DeploymentPlanner {
    37  	return shardAwareDeploymentPlanner{options: options}
    38  }
    39  
    40  func (dp shardAwareDeploymentPlanner) DeploymentSteps(p placement.Placement) [][]placement.Instance {
    41  	instances := p.Instances()
    42  	sort.Sort(placement.ByIDAscending(instances))
    43  	var steps sortableSteps
    44  	for len(instances) > 0 {
    45  		step := getDeployStep(instances, dp.options.MaxStepSize())
    46  		steps = append(steps, step)
    47  		instances = getLeftInstances(instances, step)
    48  	}
    49  	sort.Sort(steps)
    50  	return steps
    51  }
    52  
    53  func getDeployStep(instances []placement.Instance, maxStepSize int) []placement.Instance {
    54  	var parallel []placement.Instance
    55  	shards := make(map[uint32]struct{})
    56  	for _, instance := range instances {
    57  		if len(parallel) >= maxStepSize {
    58  			break
    59  		}
    60  		if isSharingShard(shards, instance) {
    61  			continue
    62  		}
    63  		parallel = append(parallel, instance)
    64  		for _, s := range instance.Shards().All() {
    65  			shards[s.ID()] = struct{}{}
    66  		}
    67  	}
    68  	return parallel
    69  }
    70  
    71  func isSharingShard(shards map[uint32]struct{}, instance placement.Instance) bool {
    72  	for _, s := range instance.Shards().All() {
    73  		if _, exist := shards[s.ID()]; exist {
    74  			return true
    75  		}
    76  	}
    77  	return false
    78  }
    79  
    80  func getLeftInstances(all, toBeRemoved []placement.Instance) []placement.Instance {
    81  	for _, instance := range toBeRemoved {
    82  		all = removeInstance(all, instance)
    83  	}
    84  	return all
    85  }
    86  
    87  func removeInstance(all []placement.Instance, remove placement.Instance) []placement.Instance {
    88  	for i, instance := range all {
    89  		if instance.ID() == remove.ID() {
    90  			return append(all[:i], all[i+1:]...)
    91  		}
    92  	}
    93  	return all
    94  }
    95  
    96  type sortableSteps [][]placement.Instance
    97  
    98  func (s sortableSteps) Len() int {
    99  	return len(s)
   100  }
   101  
   102  func (s sortableSteps) Less(i, j int) bool {
   103  	return len(s[i]) > len(s[j])
   104  }
   105  
   106  func (s sortableSteps) Swap(i, j int) {
   107  	s[i], s[j] = s[j], s[i]
   108  }