Cherry-pick #9105 to 1.81.x (#9106)

Addresses: #7023

Original PR: #9105

RELEASE NOTES:
* grpc: enhance RPC failure error messages to indicate when retries are
exhausted.

Author: arjan-bal

stream.go

@@ -148,15 +148,6 @@ type ClientStream interface {
 	RecvMsg(m any) error
 }
 
-// ErrRetriesExhausted is returned when an RPC exceeds its configured maximum
-// number of retry attempts.
-//
-// # Experimental
-//
-// Notice: This type is EXPERIMENTAL and may be changed or removed in a
-// later release.
-var ErrRetriesExhausted = errors.New("max retry attempts exhausted")
-
 // NewStream creates a new Stream for the client side. This is typically
 // called by generated code. ctx is used for the lifetime of the stream.
 //
@@ -759,7 +750,7 @@ func (a *csAttempt) shouldRetry(err error) (bool, error) {
 		return false, err
 	}
 	if cs.numRetries+1 >= rp.MaxAttempts {
-		return false, fmt.Errorf("stopped after %d attempts: %w: %w", cs.numRetries+1, ErrRetriesExhausted, err)
+		return false, fmt.Errorf("max retries exhausted: failed after %d attempts: %w", cs.numRetries+1, err)
 	}
 
 	var dur time.Duration

test/retry_test.go

@@ -20,7 +20,6 @@ package test
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -576,8 +575,8 @@ func (s) TestMaxCallAttempts(t *testing.T) {
 				t.Fatalf("client: Recv() = %s, %v; want <nil>, error", got, err)
 			} else if status.Code(err) != codes.Unavailable {
 				t.Fatalf("client: Recv() = _, %v; want _, Unavailable", err)
-			} else if !errors.Is(err, grpc.ErrRetriesExhausted) {
-				t.Fatalf("want: ErrRetriesExhausted, got: %v", err)
+			} else if !strings.Contains(err.Error(), "retries exhausted") {
+				t.Fatalf("want: retries exhausted, got: %v", err)
 			}
 
 			serverMu.Lock()
@@ -910,8 +909,8 @@ func (s) TestNoRetry(t *testing.T) {
 			if status.Code(err) != codes.Unavailable {
 				t.Fatalf("client: Recv() = _, %v; want _, Unavailable", err)
 			}
-			if errors.Is(err, grpc.ErrRetriesExhausted) {
-				t.Fatalf("client: Recv() error matches ErrRetriesExhausted, want not match")
+			if strings.Contains(err.Error(), "retries exhausted") {
+				t.Fatalf("client: EmptyCall() failed with an unexpected 'retries exhausted' error: %v", err)
 			}
 
 			// Test unary RPC
@@ -922,8 +921,9 @@ func (s) TestNoRetry(t *testing.T) {
 			if status.Code(err) != codes.Unavailable {
 				t.Fatalf("client: EmptyCall() = _, %v; want _, Unavailable", err)
 			}
-			if errors.Is(err, grpc.ErrRetriesExhausted) {
-				t.Fatalf("client: EmptyCall() error matches ErrRetriesExhausted, want not match")
+
+			if strings.Contains(err.Error(), "retries exhausted") {
+				t.Fatalf("client: EmptyCall() failed with an unexpected 'retries exhausted' error: %v", err)
 			}
 		})
 	}