86 lines
1.9 KiB
Go
86 lines
1.9 KiB
Go
package dispatch
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import (
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"errors"
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"sync/atomic"
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"time"
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proxyDomain "proxy-pool/internal/domain/proxy"
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"proxy-pool/internal/gateway/snapshot"
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)
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var ErrNoCandidate = errors.New("no local proxy candidate is available")
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type Request struct {
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Now time.Time
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Scheme proxyDomain.Scheme
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Upstreams []string
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RequiredTags map[string]string
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Exclude map[string]struct{}
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SafetyMargin time.Duration
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}
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type Lease struct {
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Proxy proxyDomain.Proxy
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Epoch uint64
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Version uint64
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reserved *proxyDomain.Reservation
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}
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func (l *Lease) Commit() error { return l.reserved.Commit() }
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func (l *Lease) Cancel() error { return l.reserved.Cancel() }
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func (l *Lease) Release() error { return l.reserved.Release() }
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type Dispatcher struct {
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store *snapshot.Store
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cursor atomic.Uint64
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}
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func New(store *snapshot.Store) *Dispatcher {
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return &Dispatcher{store: store}
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}
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func (d *Dispatcher) Acquire(request Request) (*Lease, error) {
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if d == nil || d.store == nil {
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return nil, ErrNoCandidate
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}
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view := d.store.Current()
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if view == nil || len(view.Entries) == 0 {
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return nil, ErrNoCandidate
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}
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if request.Now.IsZero() {
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request.Now = time.Now().UTC()
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}
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selection := view.Select(snapshot.Query{
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Now: request.Now,
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Scheme: request.Scheme,
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Upstreams: request.Upstreams,
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RequiredTags: request.RequiredTags,
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Exclude: request.Exclude,
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SafetyMargin: request.SafetyMargin,
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})
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if selection.Len() == 0 {
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return nil, ErrNoCandidate
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}
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start := int((d.cursor.Add(1) - 1) % uint64(selection.Len()))
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for offset := 0; offset < selection.Len(); offset++ {
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entry, ok := selection.EntryAt((start + offset) % selection.Len())
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if !ok {
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continue
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}
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reservation, ok := entry.Runtime.Reserve()
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if !ok {
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continue
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}
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return &Lease{
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Proxy: entry.Proxy,
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Epoch: view.Epoch,
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Version: view.Version,
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reserved: reservation,
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}, nil
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}
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return nil, ErrNoCandidate
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}
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