redis: log recovery when a connection succeeds after a prior dial error

Operators currently only see repeated dial-error logs and have no
explicit signal when the pool starts succeeding again. Track whether
the last dial attempt failed and log once when a subsequent connection
succeeds.

Signed-off-by: kiran malsetty <kiran.malsetty@outsystems.com>

Author: OS-kiranmalsetty

src/redis/driver_impl.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net"
 	"strings"
+	"sync/atomic"
 	"time"
 
 	"github.com/jpillora/backoff"
@@ -23,13 +24,15 @@ type poolStats struct {
 	connectionActive stats.Gauge
 	connectionTotal  stats.Counter
 	connectionClose  stats.Counter
+	hadConnError     *atomic.Bool
 }
 
 func newPoolStats(scope stats.Scope) poolStats {
 	ret := poolStats{}
 	ret.connectionActive = scope.NewGauge("cx_active")
 	ret.connectionTotal = scope.NewCounter("cx_total")
 	ret.connectionClose = scope.NewCounter("cx_local_close")
+	ret.hadConnError = new(atomic.Bool)
 	return ret
 }
 
@@ -39,13 +42,17 @@ func poolTrace(ps *poolStats, healthCheckActiveConnection bool, srv server.Serve
 			if newConn.Err == nil {
 				ps.connectionTotal.Add(1)
 				ps.connectionActive.Add(1)
+				if ps.hadConnError.CompareAndSwap(true, false) {
+					logger.Infof("redis connection re-established after previous error")
+				}
 				if healthCheckActiveConnection && srv != nil {
 					err := srv.HealthChecker().Ok(server.RedisHealthComponentName)
 					if err != nil {
 						logger.Errorf("Unable to update health status: %s", err)
 					}
 				}
 			} else {
+				ps.hadConnError.Store(true)
 				logger.Errorf("creating redis connection error : %v", newConn.Err)
 			}
 		},