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54 lines
1.2 KiB
54 lines
1.2 KiB
package selector
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import (
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"context"
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"sync"
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)
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// Default is composite selector.
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type Default struct {
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NodeBuilder WeightedNodeBuilder
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Balancer Balancer
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Filters []Filter
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lk sync.RWMutex
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weightedNodes []Node
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}
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// Select select one node.
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func (d *Default) Select(ctx context.Context, opts ...SelectOption) (selected Node, done DoneFunc, err error) {
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d.lk.RLock()
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weightedNodes := d.weightedNodes
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d.lk.RUnlock()
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for _, f := range d.Filters {
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weightedNodes = f(ctx, weightedNodes)
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}
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var options SelectOptions
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for _, o := range opts {
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o(&options)
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}
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for _, f := range options.Filters {
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weightedNodes = f(ctx, weightedNodes)
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}
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candidates := make([]WeightedNode, 0, len(weightedNodes))
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for _, n := range weightedNodes {
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candidates = append(candidates, n.(WeightedNode))
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}
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if len(candidates) == 0 {
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return nil, nil, ErrNoAvailable
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}
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return d.Balancer.Pick(ctx, candidates)
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}
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// Apply update nodes info.
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func (d *Default) Apply(nodes []Node) {
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weightedNodes := make([]Node, 0, len(nodes))
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for _, n := range nodes {
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weightedNodes = append(weightedNodes, d.NodeBuilder.Build(n))
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}
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d.lk.Lock()
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// TODO: Do not delete unchanged nodes
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d.weightedNodes = weightedNodes
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d.lk.Unlock()
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}
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