Catching timeout errors with ruby mechanize - ruby

Question

I have a mechanize function to log me out of a site but on very rare occasions it times me out. The function involves going to a specific page, and then clicking on a logout button. On the occasional that mechanize suffers a timeout when either going to the logout page or clicking the logout button the code crashes. So I put in a small rescue and it seems to be working as seen below the first piece of code.
def logmeout(agent)
page = agent.get('http://www.example.com/')
agent.click(page.link_with(:text => /Log Out/i))
end
Logmeout with rescue:
def logmeout(agent)
begin
page = agent.get('http://www.example.com/')
agent.click(page.link_with(:text => /Log Out/i))
rescue Timeout::Error
puts "Timeout!"
retry
end
end
Assuming I understand rescue correctly, it will do both actions over even if just the clicking timed out, so in the effort to be efficient I am was wondering if I could use a proc in this situation and pass it a code block. Would something like this work:
def trythreetimes
tries = 0
begin
yield
rescue
tries += 1
puts "Trying again!"
retry if tries <= 3
end
end
def logmeout(agent)
trythreetimes {page = agent.get('http://www.example.com/')}
trythreetimes {agent.click(page.link_with(:text => /Log Out/i))}
end
Note in my trythreetimes function I left it as generic rescue so the function would be more re-usable.
Thanks so much for any help anyone can provide, I realize there are a couple different questions in here but they are all things I am trying to learn!

Answer 1

Instead of retrying some timeouts on some mechanize requests I think you'd better set Mechanize::HTTP::Agent::read_timeout attribute to a reasonable amount of seconds like 2 or 5, anyway one that prevent timeouts errors for this request.
Then, it seem's that your log out procedure only required access to a simple HTTP GET request. I mean there is no form to fill in so no HTTP POST request.
So if I were you, I would prefere inspected the page source code (Ctrl+U with Firefox or Chrome) in order to identify the link which is reached by your agent.click(page.link_with(:text => /Log Out/i))
It should be faster because these type of pages are usually blank and Mechanize will not have to load a full html web page in memory.
Here is the code I would prefer use :
def logmeout(agent)
begin
agent.read_timeout=2 #set the agent time out
page = agent.get('http://www.example.com/logout_url.php')
agent.history.pop() #delete this request in the history
rescue Timeout::Error
puts "Timeout!"
puts "read_timeout attribute is set to #{agent.read_timeout}s" if !agent.read_timeout.nil?
#retry #retry is no more needed
end
end
but you can use your retry function too :
def trythreetimes
tries = 0
begin
yield
rescue Exception => e
tries += 1
puts "Error: #{e.message}"
puts "Trying again!" if tries <= 3
retry if tries <= 3
puts "No more attempt!"
end
end
def logmeout(agent)
trythreetimes do
agent.read_timeout=2 #set the agent time out
page = agent.get('http://www.example.com/logout_url.php')
agent.history.pop() #delete this request in the history
end
end
hope it helps ! ;-)

Answer 2

Using mechanize 1.0.0 I got this problem from a different source of error.
In my case I was blocked by proxy and then SSL. This worked for me:
ag = Mechanize.new
ag.set_proxy('yourproxy', yourport)
ag.agent.http.verify_mode = OpenSSL::SSL::VERIFY_NONE
ag.get( url )