[GNC-dev] Robust error handling and respecting the Apha Vantage API limits in gnc-fq-helper.

[Mike Alexander]

I'm glad you're looking at this since it does need some work.  However I 
think there are a couple of things you're not aware of.  I, too, have 
quite a ffew currencies in my file (around 30) and by coincidence I was 
running a price fetch in the background when I first saw your message.  
It completed successfully after fetching all currency quotes as usual.

You're right that GnuCash fetches one currency per call, but this is the 
only API for currencies that F::Q provides.  It fetches all the other 
quotes for a given source in one call to F::Q.  The F::Q currency quote 
code has a test for the rate limiting message that AlphaVantage returns 
when currency quote fetches come too fast.  However at some time in the 
past AlphaVantage changed this message.  I updated F::Q to look for the 
new message and sent a pull request upstream.  This pul request has 
never been applied which means that the current F::Q does not recognize 
when AlphaVantage is trying to tell it to slow down.  My copy of F::Q 
has this change which is probably why it works for me and not for you.

The patch is simple, just change it to look for a "Note" field in the 
returned data instead of an "Information" field.

Try this and see if it helps.

Your change to make GnuCash handle F::Q failures better seems like a 
good idea.  Putting the delay on GnuCash's side of the API might also be 
a good idea, but really shouldn't be necessary.  It also would be a 
problem for someone who has actually paid for an AlphaVantage 
subscription and hence can get currency quotes faster.  Some day I hope 
that F::Q will find a currency quote source that works better and faster 
at which time you wouldn't want the delay in GnuCash.

         Mike

diff --git a/lib/Finance/Quote.pm b/lib/Finance/Quote.pm
index b66bca9..6703935 100644
--- lib/Finance/Quote.pm
+++ lib/Finance/Quote.pm
@@ -274,9 +274,9 @@ sub currency {
      if ( !$json_data || $json_data->{'Error Message'} ) {
        return undef;
      }
-#     print "Failed: " . $json_data->{'Information'} . "\n" if 
(($try_cnt < 5) && ($json_data->{'Information'}));
-    sleep (20) if (($try_cnt < 5) && ($json_data->{'Information'}));
-  } while (($try_cnt < 5) && ($json_data->{'Information'}));
+#     print "Failed: " . $json_data->{'Note'} . "\n" if (($try_cnt < 5) 
&& ($json_data->{'Note'}));
+    sleep (20) if (($try_cnt < 5) && ($json_data->{'Note'}));
+  } while (($try_cnt < 5) && ($json_data->{'Note'}));

    my $exchange_rate = $json_data->{'Realtime Currency Exchange 
Rate'}->{'5. Exchange Rate'};