github.com/m3db/m3@v1.5.0/src/dbnode/topology/host.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 topology
    22  
    23  import (
    24  	"errors"
    25  	"fmt"
    26  	"math"
    27  
    28  	"github.com/m3db/m3/src/cluster/services"
    29  	"github.com/m3db/m3/src/cluster/shard"
    30  	"github.com/m3db/m3/src/dbnode/sharding"
    31  )
    32  
    33  var errInstanceHasNoShardsAssignment = errors.New("invalid instance with no shards assigned")
    34  
    35  // Majority returns the majority required to successfully return when
    36  // querying a majority of a set of replicas
    37  func Majority(replicas int) int {
    38  	return int(math.Ceil(0.5 * float64(replicas+1)))
    39  }
    40  
    41  type host struct {
    42  	id      string
    43  	address string
    44  }
    45  
    46  func (h *host) ID() string {
    47  	return h.id
    48  }
    49  
    50  func (h *host) Address() string {
    51  	return h.address
    52  }
    53  
    54  func (h *host) String() string {
    55  	return fmt.Sprintf("Host<ID=%s, Address=%s>", h.id, h.address)
    56  }
    57  
    58  // NewHost creates a new host
    59  func NewHost(id, address string) Host {
    60  	return &host{id: id, address: address}
    61  }
    62  
    63  type hostShardSet struct {
    64  	host     Host
    65  	shardSet sharding.ShardSet
    66  }
    67  
    68  // NewHostShardSet creates a new host shard set
    69  func NewHostShardSet(host Host, shardSet sharding.ShardSet) HostShardSet {
    70  	return &hostShardSet{host, shardSet}
    71  }
    72  
    73  // NewHostShardSetFromServiceInstance creates a new
    74  // host shard set derived from a service instance
    75  func NewHostShardSetFromServiceInstance(
    76  	si services.ServiceInstance,
    77  	fn sharding.HashFn,
    78  ) (HostShardSet, error) {
    79  	if si.Shards() == nil {
    80  		return nil, errInstanceHasNoShardsAssignment
    81  	}
    82  	all := si.Shards().All()
    83  	shards := make([]shard.Shard, len(all))
    84  	copy(shards, all)
    85  	shardSet, err := sharding.NewShardSet(shards, fn)
    86  	if err != nil {
    87  		return nil, err
    88  	}
    89  	return NewHostShardSet(NewHost(si.InstanceID(), si.Endpoint()), shardSet), nil
    90  }
    91  
    92  func (h *hostShardSet) Host() Host {
    93  	return h.host
    94  }
    95  
    96  func (h *hostShardSet) ShardSet() sharding.ShardSet {
    97  	return h.shardSet
    98  }