Executing a Broken Statement Causes a Hang

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#54 1 comment 1 reaction 0 assignees View on GitHub

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
42/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
go, sqlite
Domain
databases

Research direction

Run the provided main.go reproduction and trace the sqlitepool.NewPool, BeginTx, and transaction.Exec entry points. Determine why an invalid statement in a transaction does not return and verify the fix by confirming the example reports an error instead of hanging.

Written by the indexing model from the issue text.

Description

Hi,

whenever you try to execute an invalid statement in a transaction an error isn't returned (nor a panic thrown) the program just hangs.

I'd initially noticed this when inserting twice into a table that expected a column to be unique assuming I'd see an error but instead the program just hung.

this does not seem to be directly related to the unique constraint, it seems to happened with any invalid statement; even if they aren't valid SQL.

here's a example:

package main

import (
	"context"
	"log"

	"github.com/tailscale/sqlite/sqliteh"
	"github.com/tailscale/sqlite/sqlitepool"
)

var db *sqlitepool.Pool

func init() {
	var err error

	db, err = sqlitepool.NewPool("file:./db.sqlite", 10, func(init sqliteh.DB) error { return nil }, nil)

	if err != nil {
		panic(err)
	}
}

func main() {
	defer db.Close()

	transaction, err := db.BeginTx(context.Background(), "")

	if err != nil {
		panic(err)
	}

	log.Println("executing invalid statement")

	err = transaction.Exec("this should throw an error")

	if err != nil {
		panic(err)
	}

	log.Println("done")

	err = transaction.Commit()

	if err != nil {
		panic(err)
	}
}

running this program yields the following then hangs forever:

% go run main.go
2023/03/01 22:43:26 executing invalid statement
Dominant language
C
Stars
225
Forks
11
Avg merge
20m
Merged PRs (30d)
2

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