bzr push into mysql-5.6 branch (jorgen.loland:4210 to 4211)

[Jorgen Loland]

 4211 Jorgen Loland	2012-08-30 [merge]
      Null-merge from 5.5

 4210 Sunny Bains	2012-08-30
      Bug#14555404 SHOW INNODB STATUS AND I_S SHOW WRONG TRANSACTION START TIME AND DURATION
      
      Revert:
       revno: 3728
       revision-id: sunny.bains@stripped
       parent: inaam.rana@stripped
       committer: Sunny Bains <Sunny.Bains@stripped>
       branch nick: trunk
       timestamp: Tue 2012-04-24 12:48:19 +1000
       message:
        Bug#13993661 - GET RID OF STATIC COUNTER IN TRX_START_LOW(), USE THE TRX_T::ID AS THE COUNTER
      
          In trx_start_low() we use a static counter to control the number of
          gettimeofday() calls we make to set the trx_t::start_time. The trx_t::id
          is also a monotonically increasing counter and is local to the thread.
          Use that instead. This should reduce potential cache coherency issues.
      
          Approved by Inaam over IM.
      
      There is one additional change, remove the "optimisation" for the auto-commit
      read-only optimisation too.
      
      We should set the transaction start time from the session variables ideally
      and avoid all calls to set the time. Perhaps even get rid of this field from
      trx_t.
      
      Approved by Jimmy Yand over IM.

    modified:
      storage/innobase/trx/trx0trx.cc
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