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scan.go
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scan.go
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package evutil
import (
"context"
"sync"
db "github.com/alxarch/evdb"
)
// MuxScanner multiplexes ScanQuerier instances into a Scanner
type MuxScanner map[string]db.ScanQuerier
// Set assigns a ScanQuerier instance to some events
func (m MuxScanner) Set(s db.ScanQuerier, events ...string) MuxScanner {
if m == nil {
m = make(map[string]db.ScanQuerier)
}
for _, event := range events {
m[event] = s
}
return m
}
// Scan implements Scanner
func (m MuxScanner) Scan(ctx context.Context, queries ...db.ScanQuery) (db.Results, error) {
queries = db.ScanQueries(queries).Compact()
wg := new(sync.WaitGroup)
errc := make(chan error, len(queries))
var out db.Results
var mu sync.Mutex
for i := range queries {
q := &queries[i]
s := m[q.Event]
if s == nil {
continue
}
wg.Add(1)
go func() {
defer wg.Done()
// Merge all overlapping queries
results, err := s.ScanQuery(ctx, q)
if err == nil {
mu.Lock()
out = append(out, results...)
mu.Unlock()
}
errc <- err
}()
}
wg.Wait()
close(errc)
for err := range errc {
if err != nil {
return nil, err
}
}
return out, nil
}