153 lines
3 KiB
Go
153 lines
3 KiB
Go
package events
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import (
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"encoding/hex"
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"fmt"
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"hash"
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"io"
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"path"
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"path/filepath"
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"strconv"
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"strings"
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"sync"
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"github.com/google/uuid"
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"github.com/baez90/goveal/fs"
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)
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const (
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baseDecimal = 10
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)
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type (
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EventMutation interface {
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OnEvent(in ContentEvent, ev fs.Event) (out ContentEvent)
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}
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ContentEvent struct {
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File string `json:"file"`
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FileNameHash string `json:"fileNameHash"`
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Timestamp string `json:"ts"`
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ForceReload bool `json:"forceReload"`
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ReloadConfig bool `json:"reloadConfig"`
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}
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EventSource interface {
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io.Closer
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fs.FS
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Events() chan fs.Event
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}
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EventHandler interface {
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OnEvent(ev ContentEvent) error
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}
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EventHandlerFunc func(ev ContentEvent) error
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subscription struct {
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EventHandler
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OnError chan error
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}
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MutationReloadForFile string
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MutationConfigReloadForFile string
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)
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func (t MutationReloadForFile) OnEvent(in ContentEvent, ev fs.Event) (out ContentEvent) {
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if strings.EqualFold(filepath.Base(ev.File), string(t)) {
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in.ForceReload = true
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}
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return in
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}
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func (t MutationConfigReloadForFile) OnEvent(in ContentEvent, ev fs.Event) (out ContentEvent) {
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if strings.EqualFold(filepath.Base(ev.File), string(t)) {
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in.ReloadConfig = true
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}
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return in
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}
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func (f EventHandlerFunc) OnEvent(ev ContentEvent) error {
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return f(ev)
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}
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func NewEventHub(eventSource EventSource, fileNameHash hash.Hash, mutations ...EventMutation) *EventHub {
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hub := &EventHub{
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FileNameHash: fileNameHash,
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mutations: mutations,
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source: eventSource,
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subscriptions: make(map[uuid.UUID]*subscription),
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done: make(chan struct{}),
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}
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go hub.processEvents()
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return hub
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}
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type EventHub struct {
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FileNameHash hash.Hash
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mutations []EventMutation
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lock sync.RWMutex
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done chan struct{}
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source EventSource
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subscriptions map[uuid.UUID]*subscription
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}
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func (h *EventHub) Subscribe(handler EventHandler) (id uuid.UUID, onError <-chan error) {
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h.lock.Lock()
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defer h.lock.Unlock()
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s := &subscription{
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EventHandler: handler,
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OnError: make(chan error),
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}
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clientID := uuid.New()
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h.subscriptions[clientID] = s
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return clientID, s.OnError
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}
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func (h *EventHub) Unsubscribe(id uuid.UUID) {
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h.lock.Lock()
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defer h.lock.Unlock()
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delete(h.subscriptions, id)
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}
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func (h *EventHub) Close() error {
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close(h.done)
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return h.source.Close()
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}
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func (h *EventHub) processEvents() {
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events := h.source.Events()
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for {
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select {
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case ev, more := <-events:
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if !more {
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return
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}
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h.notifySubscribers(ev)
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case _, more := <-h.done:
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if !more {
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return
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}
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}
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}
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}
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func (h *EventHub) notifySubscribers(ev fs.Event) {
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h.lock.RLock()
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defer h.lock.RUnlock()
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ce := ContentEvent{
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File: fmt.Sprintf("/%s", ev.File),
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Timestamp: strconv.FormatInt(ev.Timestamp.Unix(), baseDecimal),
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FileNameHash: hex.EncodeToString(h.FileNameHash.Sum([]byte(path.Base(ev.File)))),
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}
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for idx := range h.mutations {
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ce = h.mutations[idx].OnEvent(ce, ev)
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}
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for _, handler := range h.subscriptions {
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if err := handler.OnEvent(ce); err != nil {
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handler.OnError <- err
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}
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}
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}
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