Add some very simple test cases (and resulting bug fixes) for release_memory(). (CVS 2826)

FossilOrigin-Name: 154282fca54bf03d310d6931660f99805bb5477f

test/malloc5.test

@@ -0,0 +1,128 @@
+# 2005 November 30
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+# $Id: malloc5.test,v 1.1 2005/12/19 14:18:12 danielk1977 Exp $
+
+#---------------------------------------------------------------------------
+# NOTES ON EXPECTED BEHAVIOUR
+#
+#---------------------------------------------------------------------------
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+do_test malloc5-1.1 {
+  # Simplest possible test. Call [db release_memory] when there is exactly
+  # one unused page in a single pager cache. This test case set's the 
+  # value of the ::pgalloc variable, which is used in subsequent tests.
+  #
+  # Note: Even though executing this statement on an empty database 
+  # modifies 2 pages (the root of sqlite_master and the new root page), 
+  # the sqlite_master root (page 1) is never freed because the btree layer
+  # retains a reference to it for the entire transaction. 
+  execsql {
+    BEGIN;
+    CREATE TABLE abc(a, b, c);
+  }
+  set ::pgalloc [db release_memory]
+  expr $::pgalloc > 0
+} {1}
+do_test malloc5-1.2 {
+  # Test that the transaction started in the above test is still active.
+  # Because the page freed had been written to, freeing it required a
+  # journal sync and exclusive lock on the database file. Test the file
+  # appears to be locked.
+  sqlite3 db2 test.db
+  catchsql {
+    SELECT * FROM abc;
+  } db2
+} {1 {database is locked}}
+do_test malloc5-1.3 {
+  # Again call [db release_memory] when there is exactly one unused page 
+  # in the cache. The same amount of memory is required, but no journal-sync
+  # or exclusive lock should be established.
+  execsql {
+    COMMIT;
+    BEGIN;
+    SELECT * FROM abc;
+  }
+  db release_memory
+} $::pgalloc
+do_test malloc5-1.4 {
+  # Database should not be locked this time.
+  catchsql {
+    SELECT * FROM abc;
+  } db2
+} {0 {}}
+do_test malloc5-1.5 {
+  # Manipulate the cache so that it contains two unused pages. One requires 
+  # a journal-sync to free, the other does not.
+  execsql {
+    SELECT * FROM abc;
+    CREATE TABLE def(d, e, f);
+  }
+  db release_memory 500
+} $::pgalloc
+do_test malloc5-1.6 {
+  # Database should not be locked this time. The above test case only
+  # requested 500 bytes of memory, which can be obtained by freeing the page
+  # that does not require an fsync().
+  catchsql {
+    SELECT * FROM abc;
+  } db2
+} {0 {}}
+do_test malloc5-1.7 {
+  # Release another 500 bytes of memory. This time we require a sync(), 
+  # so the database file will be locked afterwards.
+  db release_memory 500
+} $::pgalloc
+do_test malloc5-1.8 {
+  catchsql {
+    SELECT * FROM abc;
+  } db2
+} {1 {database is locked}}
+do_test malloc5-1.9 {
+  execsql {
+    COMMIT;
+  }
+} {}
+
+
+do_test malloc5-2.1 {
+  # Put some data in tables abc and def. Both tables are still wholly 
+  # contained within their root pages.
+  execsql {
+    INSERT INTO abc VALUES(1, 2, 3);
+    INSERT INTO abc VALUES(4, 5, 6);
+    INSERT INTO def VALUES(7, 8, 9);
+    INSERT INTO def VALUES(10,11,12);
+  }
+} {}
+do_test malloc5-2.2 {
+  # Load the root-page for table def into the cache. Then query table abc. 
+  # Halfway through the query call sqlite3_release_memory(). The goal of this
+  # test is to make sure we don't free pages that are in use (specifically, 
+  # the root of table abc).
+  set nRelease 0
+  execsql { 
+    BEGIN;
+    SELECT * FROM def;
+  }
+  db eval {SELECT * FROM abc} {
+    incr nRelease [db release_memory]
+    lappend data $a $b $c
+  }
+  list $nRelease $data
+} [list $pgalloc [list 1 2 3 4 5 6]]
+
+finish_test
+
+