SQLite

#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# This file contains test cases focused on the two memory-management APIs, 
# sqlite3_soft_heap_limit() and sqlite3_release_memory().
#
# $Id: malloc5.test,v 1.17 2007/10/03 09:43:55 danielk1977 Exp $

#---------------------------------------------------------------------------
# NOTES ON EXPECTED BEHAVIOUR
#
#---------------------------------------------------------------------------

  execsql {BEGIN;}
  for {set i 0} {$i < 10000} {incr i} {
    execsql "INSERT INTO abc VALUES($i, $i, '[string repeat X 100]');"
  }
  execsql {COMMIT;}
  set nMaxBytes [sqlite3_memory_highwater 1]
  puts -nonewline " (Highwater mark: $nMaxBytes) "

  # We used to test ($nMaxBytes<100000), because the soft-heap-limit is
  # 100000 bytes. But if an allocation that will exceed the 
  # soft-heap-limit is requested from within the only pager instance in 
  # the system, then there is no way to free memory and the limit has to 
  # be exceeded. An exception is memory allocated to store actual page
  # data (the code contains a special case for this).
  #
  # This is not a problem because all allocations apart from those
  # used to store cached page data are both small and transient.
  #
  # Summary: the actual high-water mark for memory usage may be slightly 
  # higher than the soft-heap-limit. The specific allocations that cause
  # the problem are the calls to sqlite3_malloc() inserted into selected
  # sqlite3OsXXX() functions in test builds.
  #
  expr $nMaxBytes <= 100100
} {1}
do_test malloc5-4.3 {
  # Check that the content of table abc is at least roughly as expected.
  execsql {
    SELECT count(*), sum(a), sum(b) FROM abc;
  }
} [list 20000 [expr int(20000.0 * 4999.5)] [expr int(20000.0 * 4999.5)]]