I apologzize to rise this again, it may have fallen under the radar for some reason. It is minor, too.
The documentation of the busy method of the Tcl interface to sqlite http://sqlite.org/tclsqlite.html#busy doesn't tell, that the callback procedure is called with one arg, the "number of times that the busy handler has been invoked previously for the same locking event" (as the documentation sqlite3_busy_handler() at https://www.sqlite.org/c3ref/busy_handler.html words it). The documentation also doesn't note, how the timeout and busy methods interfere. The appended script illustrates the current implementation. rolf package require sqlite3 sqlite3 one tmp.db one eval { CREATE TABLE IF NOT EXISTS some(value text); INSERT INTO some VALUES('foo'); BEGIN IMMEDIATE TRANSACTION } proc busyhandler {args} { global counter puts "args: '$args'" incr counter if {$counter > 3} { return 1 } return 0 } sqlite3 two tmp.db two busy busyhandler catch {two eval { DELETE FROM some }} errMsg puts $errMsg two timeout 500 catch {two eval { DELETE FROM some }} errMsg puts $errMsg two busy busyhandler catch {two eval { DELETE FROM some }} errMsg puts $errMsg Rolf Ade <r...@pointsman.de> writes: > The documentation of the busy method at > > http://sqlite.org/tclsqlite.html#busy > > should be more specific, with regards of the arguments of the Tcl > callback procedure. > > The documentation currently reads: > > The "busy" method, like "timeout", only comes into play when the > database is locked. But the "busy" method gives the programmer much > more control over what action to take. The "busy" method specifies a > callback Tcl procedure that is invoked whenever SQLite tries to open > a locked database. This callback can do whatever is desired. > Presumably, the callback will do some other useful work for a short > while (such as service GUI events) then return so that the lock can > be tried again. The callback procedure should return "0" if it wants > SQLite to try again to open the database and should return "1" if it > wants SQLite to abandon the current operation. > > This doesn't specify, what arguments the Tcl callback procedure must > expect. Turns out, that the proc is called with one argument (the number > of how much the busy callback was already called for the current lock > situation, it seems). That should be explictly written in the > documentation, since it doesn't seem clearly obvious. > > What must be obvious is, that English is a foreign language to me. > Therefor, I'm shy to propose a phrase. > > Another plea, since I'm already writing: It isn't immediate and without > any doubt clear, how the "timeout" and the "busy" methods play together, > if both are used. I suspect, the timeout, if given, determines, how long > it lasts until the busy callback is called (and that for every round, if > the busy callback returned "0") but if it is this way (or not) isn't > said somewhere, if I see right. > > rolf > > _______________________________________________ > sqlite-users mailing list > sqlite-users@mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
