SQLite

# Skip these tests if OMIT_MEMORY_MANAGEMENT was defined at compile time.
ifcapable !memorymanage {
   finish_test
   return
}

# The sizes of memory allocations from system malloc() might vary,
# depending on the memory allocator algorithms used.  The following
# routine is designed to support answers that fall within a range
# of values while also supplying easy-to-understand "expected" values
# when errors occur.
#
proc value_in_range {target x args} {
  set v [lindex $args 0]
  if {$v!=""} {
    if {$v<$target*$x} {return $v}
    if {$v>$target/$x} {return $v}
  }
  return "number between [expr {int($target*$x)}] and [expr {int($target/$x)}]"
}
set mrange 0.98   ;#  plus or minus 2%

test_set_config_pagecache 0 100

sqlite3_soft_heap_limit 0
sqlite3 db test.db
# db eval {PRAGMA cache_size=1}

do_test malloc5-1.1 {
  # Simplest possible test. Call sqlite3_release_memory when there is exactly
  # one unused page in a single pager cache. The page cannot be freed, as
  # it is dirty. So sqlite3_release_memory() returns 0.
  #
  execsql {

  execsql {PRAGMA cache_size=2; SELECT * FROM sqlite_master } db2
} {}
do_test malloc5-1.3 {
  # Call [sqlite3_release_memory] when there is exactly one unused page 
  # in the cache belonging to db2.
  #
  set ::pgalloc [sqlite3_release_memory]








  value_in_range 1288 0.75








} [value_in_range 1288 0.75]

do_test malloc5-1.4 {
  # Commit the transaction and open a new one. Read 1 page into the cache.
  # Because the page is not dirty, it is eligible for collection even
  # before the transaction is concluded.
  #
  execsql {

do_test malloc5-1.6 {
  # Manipulate the cache so that it contains two unused pages. One requires 
  # a journal-sync to free, the other does not.
  db2 close
  execsql {
    BEGIN;

    CREATE TABLE def(d, e, f);
    SELECT * FROM abc;
  }
  breakpoint
  value_in_range $::pgalloc $::mrange [sqlite3_release_memory 500]
} [value_in_range $::pgalloc $::mrange]

do_test malloc5-1.7 {
  # Database should not be locked this time. 
  sqlite3 db2 test.db
  catchsql { SELECT * FROM abc } db2
} {0 {}}
do_test malloc5-1.8 {
  # Try to release another block of memory. This will fail as the only

  expr [nPage db] + [nPage db2]
} {4}

do_test malloc5-6.2.2 {
  # If we now try to reclaim some memory, it should come from the db2 cache.
  sqlite3_release_memory 3000
  expr [nPage db] + [nPage db2]
} {1}
do_test malloc5-6.2.3 {
  # Access the db2 cache again, so that all the db2 pages have been used
  # more recently than all the db pages. Then try to reclaim 3000 bytes.
  # This time, 3 pages should be pulled from the db cache.
  execsql { SELECT * FROM abc } db2
  sqlite3_release_memory 3000
  expr [nPage db] + [nPage db2]
} {0}

do_test malloc5-6.3.1 {
  # Now open a transaction and update 2 pages in the db2 cache. Then
  # do a SELECT on the db cache so that all the db pages are more recently
  # used than the db2 pages. When we try to free memory, SQLite should
  # free the non-dirty db2 pages, then the db pages, then finally use
  # sync() to free up the dirty db2 pages. The only page that cannot be
  # freed is page1 of db2. Because there is an open transaction, the
  # btree layer holds a reference to page 1 in the db2 cache.
  #
  # UPDATE: No longer. As release_memory() does not cause a sync()
  execsql {
    BEGIN;
    UPDATE abc SET c = randstr(100,100) 
    WHERE rowid = 1 OR rowid = (SELECT max(rowid) FROM abc);
  } db2
  execsql { SELECT * FROM abc } db
  expr [nPage db] + [nPage db2]
} {4}
do_test malloc5-6.3.2 {
  # Try to release 7700 bytes. This should release all the 
  # non-dirty pages held by db2.
  sqlite3_release_memory [expr 7*1132]
  list [nPage db] [nPage db2]
} {0 3}
do_test malloc5-6.3.3 {
  # Try to release another 1000 bytes. This should come fromt the db
  # cache, since all three pages held by db2 are either in-use or diry.
  sqlite3_release_memory 1000
  list [nPage db] [nPage db2]
} {0 3}
do_test malloc5-6.3.4 {
  # Now release 9900 more (about 9 pages worth). This should expunge
  # the rest of the db cache. But the db2 cache remains intact, because
  # SQLite tries to avoid calling sync().
  if {$::tcl_platform(wordSize)==8} {
    sqlite3_release_memory 10500
  } else {
    sqlite3_release_memory 9900
  }
  list [nPage db] [nPage db2]
} {0 3}
do_test malloc5-6.3.5 {
  # But if we are really insistent, SQLite will consent to call sync()
  # if there is no other option. UPDATE: As of 3.6.2, SQLite will not
  # call sync() in this scenario. So no further memory can be reclaimed.
  sqlite3_release_memory 1000
  list [nPage db] [nPage db2]
} {0 3}
do_test malloc5-6.3.6 {
  # The referenced page (page 1 of the db2 cache) will not be freed no
  # matter how much memory we ask for:
  sqlite3_release_memory 31459
  list [nPage db] [nPage db2]
} {0 3}

db2 close

sqlite3_soft_heap_limit $::soft_limit
test_restore_config_pagecache
finish_test
catch {db close}