From: Ruby Newbie <rubynewbie@...>
Date: 2005-10-25T04:39:45+09:00
Subject: Re: sqlite3 busy_handler

Thanks - I was actually wondering if my class/method definition and
busy_handler invocation were correct.  As for testing, here's a little
script I whipped up which generates a collision for me every time I
run it.  But I still don't know if I'm defining or registering the
busy_handler correctly.

This runs in about 30 seconds for me on a Via C3 - it will probably
run in 5 - 10 seconds on a desktop PC/Mac.

++++++++++++++++++++++++++++++++Code below +++++++++++++++
#!/usr/local/bin/ruby

# author: Ruby Newb
# 24-oct-2005

# test sqlite3-ruby busy_handler
# create new sqlite3 db
# create table in db
# fork thread to update a field in the db, writing output to forked.txt
# execute loop to update a field in the db, writing output to forked-not.txt
# after 10000 iterations wait for the forked pid if still active

   class DbHandler
      print "in DBHandler\n"
      def busy_handler (*data)
         print "in DBHandler.busy_handler data is ",data,"\n"
         return true;
      end
   end

   def collide(updateStmt,logHandle)
      i = 0
      while (i<10000) do
         i+=1
         updateStmt.execute(i)
         logHandle.print "pass ",i," completed at ",Time.now,"\n"
      end
   #  fileHandle.close
   end

   require "sqlite3"
   db = SQLite3::Database.new('test.db')
#  db.execute("drop table test")
   db.execute("create table test (collision INTEGER)")
   handler = DbHandler.new
   db.busy_handler(handler.busy_handler(data=nil,retries=nil))
   updStmt   = db.prepare("update test set collision = ?")
   forked    = File.new("forked.txt","w")
   forkedNot = File.new("forked-not.txt","w")
   forkedPid = fork { collide(updStmt,forked) }
   begin
      collide(updStmt,forkedNot)
   rescue SQLite3::BusyException
      print "unforked branch died first"
   end
   Process::waitpid(forkedPid,Process::WNOHANG)
   db.execute("drop table test")


On 10/24/05, Jamis Buck <jamis@37signals.com> wrote:
> I'm afraid I have no idea whether the busy-handler callback actually
> works or not. It was one of those things that I implemented because
> it was in the SQLite3 API, but I didn't have a good way to unit test it.
>
> - Jamis
>
> On Oct 24, 2005, at 9:53 AM, Ruby Newbie wrote:
>
> > Having trouble getting the sqlite3 busy_handler to work. The
> > documentation
> > at http://sqlite-ruby.rubyforge.org/sqlite3/ lists *busy_handler*
> > ( data=nil
> > ) {|data, retries| ...} as the public instance method. So far I've
> > tried
> >
> > Class DbHandler
> > print "in DbHandler\n"
> > def busy_handler(*data)
> > print "in DbHandler.busy_handler\n"
> > return true;
> > end
> > end
> >
> > and registering using
> > db = SQLite3::Database.new(....)
> > db.busy_handler(DbHandler)
> >
> > as well as
> > handler = DbHandler.new
> > db.busy_handler(handler)
> >
> > as well as
> > db.busy_handler(handler.busy_handler(data=nil,retries=nil))
> >
> > My first attempt with a method named busy_handler outside of a
> > separate
> > class was no better.
> >
> > The code compiles and runs, but two separate processes running in
> > parallel
> > will lock the database - when I would expect them to both run
> > indefinitely
> > since I am never returning false from the busy_handler method I'm
> > trying to
> > invoke.
> >
> > Any ideas?
> >
>
>
>