Journal2 patches + timings + notes

[Michael Stone]

Scott,

I spent some more time with Journal2 today and implemented two minor
features; namely, 

   * display of the estimated no. of results 
        - (which helps deal with the display of empty result-sets) 

   * incremental display of results 
        - (which makes it easier to time things). 
        
Please review and consider merging my patches, which can be found in 
http://dev.laptop.org/git/users/mstone/journal2.

(That repo contains your journal2 code but none of the big pdfs or
screencasts you made since these are very time-consuming to download
onto an XO.)

I also did a bit of timing on my XO, (see the 'timing' branch), wherein
I learned, _anecdotally_ (i.e.  with sample-size n=1) that:

   * startup time seems okay, but the initial query takes about 10s to
     return results. I have about 300 MB of data indexed under
     /home/olpc, plus a bit of other junk. (~/.pinot is ~ 35 MB).
   * it takes around 4.2 seconds to fetch and display each new result
   * the standard deviation in my sample was large, e.g. about 3.3 seconds. 
   * 19 results were fetched.

Notes: 

   * I did not take care to ensure that the indexer had quiesced before
     my test run. (However, I don't think it was working hard since it
     did the bulk of the indexing yesterday; today, it only had to deal
     files changed by my editing and by the test run itself.)

   * With today's code, the search system is effectively unusable while
     the indexer is hard at work.
     
   * While I have not yet measured it carefully, it seemed to me that
     "full" indexing of a basic 767 system + activities _on XO_ may have
     taken as long as several hours.

   * With some, but not all queries, I noticed that the query failed
     because pinot failed to reply to journal2's blocking message sends
     within the usual dbus timeout of (30? 60?) seconds. I have no idea
     what was happening inside pinot.

Michael

P.S. - Thanks for the stimulating vacation entertainment.