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-rw-r--r--worker/imap/observer.go152
1 files changed, 152 insertions, 0 deletions
diff --git a/worker/imap/observer.go b/worker/imap/observer.go
new file mode 100644
index 00000000..e49744cc
--- /dev/null
+++ b/worker/imap/observer.go
@@ -0,0 +1,152 @@
+package imap
+
+import (
+ "fmt"
+ "math"
+ "sync"
+ "time"
+
+ "git.sr.ht/~rjarry/aerc/worker/types"
+ "github.com/emersion/go-imap"
+)
+
+// observer monitors the loggedOut channel of the imap client. If the logout
+// signal is received, the observer will emit a connection error to the ui in
+// order to start the reconnect cycle.
+type observer struct {
+ sync.Mutex
+ config imapConfig
+ client *imapClient
+ worker *types.Worker
+ done chan struct{}
+ autoReconnect bool
+ retries int
+ running bool
+}
+
+func newObserver(cfg imapConfig, w *types.Worker) *observer {
+ return &observer{config: cfg, worker: w, done: make(chan struct{})}
+}
+
+func (o *observer) SetClient(c *imapClient) {
+ o.Stop()
+ o.Lock()
+ o.client = c
+ o.Unlock()
+ o.Start()
+ o.retries = 0
+}
+
+func (o *observer) SetAutoReconnect(auto bool) {
+ o.autoReconnect = auto
+}
+
+func (o *observer) AutoReconnect() bool {
+ return o.autoReconnect
+}
+
+func (o *observer) isClientConnected() bool {
+ o.Lock()
+ defer o.Unlock()
+ return o.client != nil && o.client.State() == imap.SelectedState
+}
+
+func (o *observer) EmitIfNotConnected() bool {
+ if !o.isClientConnected() {
+ o.emit("imap client not connected: attempt reconnect")
+ return true
+ }
+ return false
+}
+
+func (o *observer) IsRunning() bool {
+ return o.running
+}
+
+func (o *observer) Start() {
+ if o.running {
+ o.log("runs already")
+ return
+ }
+ if o.client == nil {
+ return
+ }
+ if o.EmitIfNotConnected() {
+ return
+ }
+ go func() {
+ select {
+ case <-o.client.LoggedOut():
+ o.log("<-logout")
+ if o.autoReconnect {
+ o.emit("logged out")
+ } else {
+ o.log("ignore logout (auto-reconnect off)")
+ }
+ case <-o.done:
+ o.log("<-done")
+ }
+ o.running = false
+ o.log("stopped")
+ }()
+ o.running = true
+ o.log("started")
+}
+
+func (o *observer) Stop() {
+ if o.client == nil {
+ return
+ }
+ if o.done != nil {
+ close(o.done)
+ }
+ o.done = make(chan struct{})
+ o.running = false
+}
+
+func (o *observer) DelayedReconnect() error {
+ if o.client == nil {
+ return nil
+ }
+ var wait time.Duration
+ var reterr error
+
+ if o.retries > 0 {
+ backoff := int(math.Pow(1.8, float64(o.retries)))
+ var err error
+ wait, err = time.ParseDuration(fmt.Sprintf("%ds", backoff))
+ if err != nil {
+ return err
+ }
+ if wait > o.config.reconnect_maxwait {
+ wait = o.config.reconnect_maxwait
+ }
+
+ reterr = fmt.Errorf("reconnect in %v", wait)
+ } else {
+ reterr = fmt.Errorf("reconnect")
+ }
+
+ go func() {
+ <-time.After(wait)
+ o.emit(reterr.Error())
+ }()
+
+ o.retries++
+ return reterr
+}
+
+func (o *observer) emit(errMsg string) {
+ o.log("disconnect done->")
+ o.worker.PostMessage(&types.Done{
+ Message: types.RespondTo(&types.Disconnect{})}, nil)
+ o.log("connection error->")
+ o.worker.PostMessage(&types.ConnError{
+ Error: fmt.Errorf(errMsg),
+ }, nil)
+}
+
+func (o *observer) log(args ...interface{}) {
+ header := fmt.Sprintf("observer (%p) [running:%t]", o, o.running)
+ o.worker.Logger.Println(append([]interface{}{header}, args...)...)
+}