From f458ea1496e25fedba5fb8c08a517c2c493f2ee3 Mon Sep 17 00:00:00 2001
From: Daichi Tomaru <banaoa7543@gmail.com>
Date: Mon, 26 Dec 2022 10:38:47 +0900
Subject: [PATCH] Add MaxConnectRetryInterval client option for reconnect
 exponential backoff related to #589

Signed-off-by: Daichi Tomaru <banaoa7543@gmail.com>
---
 client.go         | 13 +++++++++++--
 options.go        | 10 ++++++++++
 options_reader.go |  5 +++++
 3 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/client.go b/client.go
index 200daa89..f0dfd7ff 100644
--- a/client.go
+++ b/client.go
@@ -255,6 +255,7 @@ func (c *client) Connect() Token {
 			return
 		}
 
+	connectRetryInterval := c.options.ConnectRetryInterval
 	RETRYCONN:
 		var conn net.Conn
 		var rc byte
@@ -262,10 +263,18 @@ func (c *client) Connect() Token {
 		conn, rc, t.sessionPresent, err = c.attemptConnection()
 		if err != nil {
 			if c.options.ConnectRetry {
-				DEBUG.Println(CLI, "Connect failed, sleeping for", int(c.options.ConnectRetryInterval.Seconds()), "seconds and will then retry, error:", err.Error())
-				time.Sleep(c.options.ConnectRetryInterval)
+				DEBUG.Println(CLI, "Connect failed, sleeping for", int(connectRetryInterval.Seconds()), "seconds and will then retry, error:", err.Error())
+				time.Sleep(connectRetryInterval)
 
 				if c.status.ConnectionStatus() == connecting { // Possible connection aborted elsewhere
+					if c.options.ConnectRetryInterval >= c.options.MaxConnectRetryInterval {
+						goto RETRYCONN
+					}
+					if cri := connectRetryInterval * 2; cri <= c.options.MaxConnectRetryInterval {
+						connectRetryInterval = cri
+					} else {
+						connectRetryInterval = c.options.MaxConnectRetryInterval
+					}
 					goto RETRYCONN
 				}
 			}
diff --git a/options.go b/options.go
index 5aaa7d95..d53fef43 100644
--- a/options.go
+++ b/options.go
@@ -88,6 +88,7 @@ type ClientOptions struct {
 	ConnectTimeout          time.Duration
 	MaxReconnectInterval    time.Duration
 	AutoReconnect           bool
+	MaxConnectRetryInterval time.Duration
 	ConnectRetryInterval    time.Duration
 	ConnectRetry            bool
 	Store                   Store
@@ -136,6 +137,7 @@ func NewClientOptions() *ClientOptions {
 		ConnectTimeout:          30 * time.Second,
 		MaxReconnectInterval:    10 * time.Minute,
 		AutoReconnect:           true,
+		MaxConnectRetryInterval: 30 * time.Second,
 		ConnectRetryInterval:    30 * time.Second,
 		ConnectRetry:            false,
 		Store:                   nil,
@@ -386,6 +388,14 @@ func (o *ClientOptions) SetAutoReconnect(a bool) *ClientOptions {
 	return o
 }
 
+// SetMaxConnectRetryInterval sets the maximum time that will be waited between connection attempts
+// when initially connecting if ConnectRetry is TRUE
+// If ConnectRetryInterval >= MaxConnectRetryInterval, ConnectRetryInterval is kept between the attempts
+func (o *ClientOptions) SetMaxConnectRetryInterval(t time.Duration) *ClientOptions {
+	o.MaxConnectRetryInterval = t
+	return o
+}
+
 // SetConnectRetryInterval sets the time that will be waited between connection attempts
 // when initially connecting if ConnectRetry is TRUE
 func (o *ClientOptions) SetConnectRetryInterval(t time.Duration) *ClientOptions {
diff --git a/options_reader.go b/options_reader.go
index 10a9e49a..e1f1698e 100644
--- a/options_reader.go
+++ b/options_reader.go
@@ -137,6 +137,11 @@ func (r *ClientOptionsReader) AutoReconnect() bool {
 	return s
 }
 
+func (r *ClientOptionsReader) MaxConnectRetryInterval() time.Duration {
+	s := r.options.MaxConnectRetryInterval
+	return s
+}
+
 // ConnectRetryInterval returns the delay between retries on the initial connection (if ConnectRetry true)
 func (r *ClientOptionsReader) ConnectRetryInterval() time.Duration {
 	s := r.options.ConnectRetryInterval