SQLite

  opendb

  #after 2000

  # This loop runs for ~20 seconds.
  #
  set iStart [clock_seconds]
  set nOp 0
  set nAttempt 0
  while { ([clock_seconds]-$iStart) < $nSecond } {

    # Each transaction does 3 operations. Each operation is either a read
    # or write of a randomly selected table (t1, t2 or t3). Set the variables
    # $SQL(1), $SQL(2) and $SQL(3) to the SQL commands used to implement
    # each operation.
    #

            DROP INDEX IF EXISTS yyy.xxx_i;
      }
      ]]
    }

    # Execute the SQL transaction.
    #
    incr nAttempt
    set rc [catch { execsql_blocking $::DB "
        BEGIN;
          $SQL(1);
          $SQL(2);
          $SQL(3);
        COMMIT;
      "

      # Hit some other kind of error. This is a malfunction.
      error $msg
    } else {
      # No error occurred. Check that any SELECT statements in the transaction
      # returned "1". Otherwise, the invariant was false, indicating that
      # some malfunction has occurred.
      foreach r $msg { if {$r != 1} { puts "Invariant check failed: $msg" } }
      incr nOp
    }
  }

  # Close the database connection and return 0.
  #
  sqlite3_close $::DB
  list $nOp $nAttempt
}

foreach {iTest xStep xPrepare} {
  1 sqlite3_blocking_step sqlite3_blocking_prepare_v2
  2 sqlite3_step          sqlite3_nonblocking_prepare_v2
} {
  forcedelete test.db test2.db test3.db

  unset -nocomplain finished
  for {set ii 0} {$ii < $nThread} {incr ii} {
    thread_spawn finished($ii) $ThreadSetup $ThreadProgram
  }
  for {set ii 0} {$ii < $nThread} {incr ii} {
    do_test notify2-$iTest.2.$ii {
      if {![info exists finished($ii)]} { vwait finished($ii) }
      incr anSuccess($xStep) [lindex $finished($ii) 0]
      incr anAttempt($xStep) [lindex $finished($ii) 1]
      expr 0
    } {0}
  }

  # Count the total number of succesful writes.
  do_test notify2-$iTest.3.1 {
    sqlite3 db test.db
    execsql {
      ATTACH 'test2.db' AS aux2;
      ATTACH 'test3.db' AS aux3;
    }
    set anWrite($xStep) [execsql {
      SELECT (SELECT max(a) FROM t1)
           + (SELECT max(a) FROM t2)
           + (SELECT max(a) FROM t3)
    }]
    db close
  } {}
}

# The following tests checks to make sure sqlite3_blocking_step() is
# faster than sqlite3_step(). "Faster" in this case means uses fewer
# CPU cycles. This is not always the same as faster in wall-clock time 
# for this type of test. The number of CPU cycles per transaction is 
# roughly proportional to the number of attempts made (i.e. one plus the 
# number of SQLITE_BUSY or SQLITE_LOCKED errors that require the transaction 
# to be retried). So this test just measures that a greater percentage of
# transactions attempted using blocking_step() succeed.
#
# The blocking_step() function is almost always faster on multi-core and is
# usually faster on single-core.  But sometimes, by chance, step() will be
# faster on a single core, in which case the
# following test will fail.
#
puts "The following test seeks to demonstrate that the sqlite3_unlock_notify()"
puts "interface helps multi-core systems to run more efficiently.  This test"
puts "sometimes fails on single-core machines."
puts [array get anWrite]
do_test notify2-3 {
  set blocking [expr {
    double($anSuccess(sqlite3_blocking_step)) /
    double($anAttempt(sqlite3_blocking_step)) 
  }]
  set non [expr {
    double($anSuccess(sqlite3_step)) /
    double($anAttempt(sqlite3_step)) 
  }]
  puts -nonewline [format " blocking: %.1f%% non-blocking %.1f%% ..." \
    [expr $blocking*100.0] [expr $non*100.0]]

  expr {$blocking > $non}
} {1}

sqlite3_enable_shared_cache $::enable_shared_cache
finish_test