107 lines
2.3 KiB
Go
107 lines
2.3 KiB
Go
package main
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import (
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"encoding/gob"
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"errors"
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"io/fs"
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"log"
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"os"
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"github.com/probakowski/go-satel"
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)
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func FilterByType(ev <-chan satel.Event, allowedTypes []satel.ChangeType) <-chan satel.Event {
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returnChan := make(chan satel.Event)
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go func() {
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for e := range ev {
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for _, allowedType := range allowedTypes {
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if allowedType == e.Type {
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returnChan <- e
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continue
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}
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}
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}
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close(returnChan)
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}()
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return returnChan
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}
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type EventKey struct {
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ChangeType satel.ChangeType
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Index int
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}
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type EventValue struct{ Value bool }
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type PersistenceRecord struct {
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Key EventKey
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Value EventValue
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}
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func persistMapOnDisk(lastSeen *map[EventKey]bool, persistenceFilePath string) {
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f, err := os.OpenFile(persistenceFilePath, os.O_WRONLY|os.O_CREATE, 0600)
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if err != nil {
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panic(err)
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}
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defer f.Close()
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enc := gob.NewEncoder(f)
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data := make([]PersistenceRecord, len(*lastSeen))
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i := 0
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for k, v := range *lastSeen {
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data[i] = PersistenceRecord{Key: k, Value: EventValue{v}}
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i += 1
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}
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err = enc.Encode(data)
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if err != nil {
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panic(err)
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}
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}
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func readMapFromDisk(persistenceFilePath string, logger *log.Logger) map[EventKey]bool {
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lastSeen := make(map[EventKey]bool)
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f, err := os.OpenFile(persistenceFilePath, os.O_RDONLY|os.O_CREATE, 0600)
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if err != nil {
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if errors.Is(err, fs.ErrNotExist) {
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// File not existing is fine, we'll create one later
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return lastSeen
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}
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panic(err)
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}
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defer f.Close()
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dec := gob.NewDecoder(f)
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data := make([]PersistenceRecord, 0)
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err = dec.Decode(&data)
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if err != nil {
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logger.Println("LastSeenFilter: Error reading persistence file", persistenceFilePath, "from disk:", err, ". Discarding and starting over.")
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return lastSeen
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}
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for _, readData := range data {
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lastSeen[readData.Key] = readData.Value.Value
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}
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return lastSeen
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}
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func FilterByLastSeen(ev <-chan satel.Event, persistenceFilePath string, logger *log.Logger) <-chan satel.Event {
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returnChan := make(chan satel.Event)
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go func() {
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lastSeen := readMapFromDisk(persistenceFilePath, logger)
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for e := range ev {
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val, ok := lastSeen[EventKey{e.Type, e.Index}]
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if !ok || val != e.Value {
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lastSeen[EventKey{e.Type, e.Index}] = e.Value
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returnChan <- e
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persistMapOnDisk(&lastSeen, persistenceFilePath)
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}
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}
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close(returnChan)
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}()
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return returnChan
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}
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