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database/sql: Stmt.Close() seem to ignore the error #37973

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Serhii1011010 opened this issue Mar 20, 2020 · 5 comments
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database/sql: Stmt.Close() seem to ignore the error #37973

Serhii1011010 opened this issue Mar 20, 2020 · 5 comments
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FrozenDueToAge WaitingForInfo Issue is not actionable because of missing required information, which needs to be provided.

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@Serhii1011010
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What version of Go are you using (go version)?

$ go version

go version go1.14.1 linux/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output
$ go env

GO111MODULE=""

GOARCH="amd64"

GOBIN=""

GOCACHE="/home/user/.cache/go-build"

GOENV="/home/user/.config/go/env"

GOEXE=""

GOFLAGS=""

GOHOSTARCH="amd64"

GOHOSTOS="linux"

GOINSECURE=""

GONOPROXY=""

GONOSUMDB=""

GOOS="linux"

GOPATH="/home/user/go"

GOPRIVATE=""

GOPROXY="https://proxy.golang.org,direct"

GOROOT="/usr/local/go"

GOSUMDB="sum.golang.org"

GOTMPDIR=""

GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"

GCCGO="gccgo"

AR="ar"

CC="gcc"

CXX="g++"

CGO_ENABLED="1"

GOMOD="/home/user/tmp/go_example1/go.mod"

CGO_CFLAGS="-g -O2"

CGO_CPPFLAGS=""

CGO_CXXFLAGS="-g -O2"

CGO_FFLAGS="-g -O2"

CGO_LDFLAGS="-g -O2"

PKG_CONFIG="pkg-config"

GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build865698656=/tmp/go-build -gno-record-gcc-switches"

What did you do?

run this code https://play.golang.org/p/hiITqzSJ5O4

package main

import (
	"github.com/DATA-DOG/go-sqlmock"

	"database/sql"
	"database/sql/driver"
	"fmt"
)

func doSQL(connection *sql.DB) error {
	statement, err := connection.Prepare("INSERT INTO something (column) VALUES($1)")
	if err != nil {
		return err
	}

	defer func() {
		err := statement.Close()
		if err != nil {
			panic(err)
		}
	}()

	_, err = statement.Exec("")
	return err
}

func main() {
	connection, mock, err := sqlmock.New()
	if err != nil {
		panic(err)
	}
	defer connection.Close()

	mock.ExpectPrepare("INSERT").
		WillBeClosed().
		WillReturnCloseError(fmt.Errorf("close error")).
		ExpectExec().
		WillReturnResult(driver.ResultNoRows)

	if err := doSQL(connection); err != nil {
		panic(err)
	}

	// we make sure that all expectations were met
	if err := mock.ExpectationsWereMet(); err != nil {
		panic(err)
	}
}

What did you expect to see?

panic because of error

What did you see instead?

nothing

Comments

It seems that the issue is not in go-sqlmock, but in go because I run the debugger and found this function https://github.com/golang/go/blob/master/src/database/sql/sql.go#L2701 being called and it returns nil and ignores error in v.ds.closeErr
@odeke-em odeke-em changed the title sql Stmt.Close() seem to ignore the error database/sql: Stmt.Close() seem to ignore the error Mar 21, 2020
@odeke-em odeke-em added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Mar 21, 2020
@odeke-em
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Thank you for reporting this bug @Sergey1011010 and welcome to the Go project!

Kindly paging @kardianos to take a look.

@Serhii1011010 Serhii1011010 mentioned this issue Mar 21, 2020
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@kardianos
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@Sergey1011010 Thanks for the report.

  1. Can you please provide a report without using sqlmock?
  2. A sql.Stmt is actually a Stmt pool. It will only actually close the stmt pool if there are no stmt dependencies that need to leave it open.
  3. In your example, you call doSQL(connection *sql.DB) error. I'm concerned with your naming, your concept might be incorrect. a *sql.DB isn't a connection, but a connection pool with zero or more connections held in it. Similarly, a *sql.Stmt may be prepared on one or more connections.
  4. If you want to see a stmt error on close, first call *db.Conn(ctx), then call Prepare on the connection (not the pool), then you could close the connection, then close the stmt, in that order (I think).

A better design I think would be to separate out the Stmt from the stmt pool concept. But that would be impossible util a sql/v2.

@kardianos kardianos added WaitingForInfo Issue is not actionable because of missing required information, which needs to be provided. and removed NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. labels Mar 21, 2020
@Serhii1011010
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@kardianos, many thanks for the explanation. If I use not pool, but real connection, the error does happen.

Can you please provide a report without using sqlmock?

Not sure how to make a real driver produce an error on Close statement.

@kardianos
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I think I can consider this a limitation of the current design, that may be worked around by using an explicit Conn. If you agree, please close.

@ALTree
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ALTree commented Jun 18, 2021

OP probably agrees, I guess. Anyway no news for about a year, I think we can archive this.

@ALTree ALTree closed this as completed Jun 18, 2021
@golang golang locked and limited conversation to collaborators Jun 18, 2022
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@kardianos @ALTree @odeke-em @gopherbot @Serhii1011010