cluster.go

// Copyright 2017 Pilosa Corp.
//
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// modification, are permitted provided that the following conditions
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// 1. Redistributions of source code must retain the above copyright
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// 2. Redistributions in binary form must reproduce the above copyright
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// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
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// CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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// DAMAGE.

package pilosa

// Cluster is a simple ICluster implementation
type Cluster struct {
	hosts     []*URI
	nextIndex int
}

// DefaultCluster creates a Cluster with no addresses
func DefaultCluster() *Cluster {
	return &Cluster{
		hosts: make([]*URI, 0),
	}
}

// NewClusterWithHost creates a Cluster with the given URIs
func NewClusterWithHost(hosts ...*URI) *Cluster {
	cluster := DefaultCluster()
	for _, host := range hosts {
		cluster.AddHost(host)
	}
	return cluster
}

// AddHost adds an address to the cluster
func (c *Cluster) AddHost(address *URI) {
	c.hosts = append(c.hosts, address)
}

// Host returns the next address in the cluster
func (c *Cluster) Host() *URI {
	if len(c.hosts) == 0 {
		return nil
	}
	// Return the transport, e.g., http from http+protobuf
	uri := c.hosts[c.nextIndex%len(c.hosts)]
	c.nextIndex = (c.nextIndex + 1) % len(c.hosts)
	return uri
}

// RemoveHost removes an address from the cluster
func (c *Cluster) RemoveHost(address *URI) {
	for i, uri := range c.hosts {
		if uri.Equals(address) {
			c.hosts = append(c.hosts[:i], c.hosts[i+1:]...)
			break
		}
	}
}

// Hosts returns all addresses in this cluster
func (c *Cluster) Hosts() []URI {
	arr := make([]URI, 0, len(c.hosts))
	for _, u := range c.hosts {
		arr = append(arr, *u)
	}
	return arr
}