proper use of sqlite3.BusyFunc using go?

Question

I am trying to execute some insert queries one query per goroutine (see code from emulating multiple requests to sqlite database as goroutine causes random panic) but most of failed with error: The database file is locked.

I found following from http://godoc.org/code.google.com/p/go-sqlite/go1/sqlite3#BusyFunc :

type BusyFunc func(count int) (retry bool)
BusyFunc is a callback function invoked by SQLite when it is unable to acquire a lock on a table. Count is the number of times that the callback has been invoked for this locking event so far. If the function returns false, then the operation is aborted. Otherwise, the function should block for a while before returning true and letting SQLite make another locking attempt.

I inserted following code:

sqlite3.BusyFunc(func(counted int) (bool) { 
    if counted > 10 { 
        return false 
    } else { 
        return true
    }
})

but it returned sqlite3.BusyFunc(func literal) evaluated but not used. Am I missing something?

LemurFromTheId · Accepted Answer · 2014-04-24 19:37:22Z

1

sqlite3.BusyFunc is a type. What you're doing is converting a function into that type, as a result you get a function of that type. Instead, you have to register your function with:

func (c *Conn) BusyFunc(f BusyFunc) (prev BusyFunc)

Basically changing "sqlite3" for the name of the conn handle should do the job, just grab the return value.

answered Apr 24, 2014 at 19:37

LemurFromTheId

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1 Comment

BalticMusicFan Over a year ago

i forgot about func (c *Conn) BusyTimeout(d time.Duration) (prev BusyFunc) too, but it must be before BusyFunc statement. Changing sqlite to connection handle solves problem.

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