connection: returing ctx.Cause error in canceled case

Returing wrapped context.Cause(ctx) error in <-ctx.Done() case.
Allows compare errors using errors.Is/As.

Fixes (#457)

Author: ermyar

CHANGELOG.md

@@ -14,7 +14,9 @@ Versioning](http://semver.org/spec/v2.0.0.html) except to the first release.
 
 ### Changed
 
-* Required Go version is `1.24` now (#456).
+- Required Go version is `1.24` now (#456).
+- Now `connection.newFuture()` in case `<-ctx.Done()` returns wrapped error
+  provided by `ctx.Cause()`. Allows you compare it using `errors.Is/As` (#457).
 
 ### Fixed
 

connection.go

@@ -984,7 +984,8 @@ func (conn *Connection) newFuture(req Request) (fut *Future) {
 	if ctx != nil {
 		select {
 		case <-ctx.Done():
-			fut.SetError(fmt.Errorf("context is done (request ID %d)", fut.requestId))
+			fut.SetError(fmt.Errorf("context is done (request ID %d) (%w)",
+				fut.requestId, context.Cause(ctx)))
 			shard.rmut.Unlock()
 			return
 		default:

errors.go

@@ -31,7 +31,7 @@ type ClientError struct {
 
 // Error converts a ClientError to a string.
 func (clierr ClientError) Error() string {
-	return fmt.Sprintf("%s (0x%x)", clierr.Msg, clierr.Code)
+	return fmt.Sprintf("%s (%#x)", clierr.Msg, clierr.Code)
 }
 
 // Temporary returns true if next attempt to perform request may succeeded.
@@ -54,11 +54,12 @@ func (clierr ClientError) Temporary() bool {
 
 // Tarantool client error codes.
 const (
-	ErrConnectionNotReady = 0x4000 + iota
-	ErrConnectionClosed   = 0x4000 + iota
-	ErrProtocolError      = 0x4000 + iota
-	ErrTimeouted          = 0x4000 + iota
-	ErrRateLimited        = 0x4000 + iota
-	ErrConnectionShutdown = 0x4000 + iota
-	ErrIoError            = 0x4000 + iota
+	ErrConnectionNotReady uint32 = 0x4000 + iota
+	ErrConnectionClosed
+	ErrProtocolError
+	ErrTimeouted
+	ErrRateLimited
+	ErrConnectionShutdown
+	ErrIoError
+	ErrCancelledCtx
 )

example_test.go

@@ -2,6 +2,7 @@ package tarantool_test
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net"
 	"regexp"
@@ -165,9 +166,11 @@ func ExamplePingRequest_Context() {
 	data, err := conn.Do(req).Get()
 	fmt.Println("Ping Resp data", data)
 	fmt.Println("Ping Error", regexp.MustCompile("[0-9]+").ReplaceAllString(err.Error(), "N"))
+	fmt.Println(errors.Is(err, context.DeadlineExceeded))
 	// Output:
 	// Ping Resp data []
-	// Ping Error context is done (request ID N)
+	// Ping Error context is done (request ID N) (context deadline exceeded)
+	// true
 }
 
 func ExampleSelectRequest() {

tarantool_test.go

@@ -3,6 +3,7 @@ package tarantool_test
 import (
 	"context"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -48,7 +49,8 @@ type Member struct {
 	Val   uint
 }
 
-var contextDoneErrRegexp = regexp.MustCompile(`^context is done \(request ID [0-9]+\)$`)
+var contextDoneErrRegexp = regexp.MustCompile(
+	fmt.Sprintf(`^context is done \(request ID [0-9]+\) \(%s\)$`, "context canceled"))
 
 func (m *Member) EncodeMsgpack(e *msgpack.Encoder) error {
 	if err := e.EncodeArrayLen(2); err != nil {
@@ -2737,6 +2739,8 @@ func TestClientRequestObjectsWithPassedCanceledContext(t *testing.T) {
 	if !contextDoneErrRegexp.Match([]byte(err.Error())) {
 		t.Fatalf("Failed to catch an error from done context")
 	}
+	// Checking that we could use errors.Is to get known about error.
+	require.True(t, errors.Is(err, context.Canceled))
 	if resp != nil {
 		t.Fatalf("Response is not nil after the occurred error")
 	}
@@ -3298,6 +3302,7 @@ func TestClientIdRequestObjectWithPassedCanceledContext(t *testing.T) {
 	resp, err := conn.Do(req).Get()
 	require.Nilf(t, resp, "Response is empty")
 	require.NotNilf(t, err, "Error is not empty")
+	require.True(t, errors.Is(err, context.Canceled))
 	require.Regexp(t, contextDoneErrRegexp, err.Error())
 }