/ Artifact Content
Login
SQLite training in Houston TX on 2019-11-05 (details)
Part of the 2019 Tcl Conference

Artifact 7bc1c8fa8a8c25fd6f7af8541d02cf6ebdb4b1e0:


# 2005 December 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.
#
#***********************************************************************
#
# The focus of the tests in this file are IO errors that occur in a shared
# cache context. What happens to connection B if one connection A encounters
# an IO-error whilst reading or writing the file-system?
#
# $Id: shared_err.test,v 1.7 2006/01/24 00:15:16 drh Exp $

proc skip {args} {}


set testdir [file dirname $argv0]
source $testdir/tester.tcl
db close

ifcapable !shared_cache||!subquery {
  finish_test
  return
}
set ::enable_shared_cache [sqlite3_enable_shared_cache 1]


# Todo: This is a copy of the [do_malloc_test] proc in malloc.test
# It would be better if these were consolidated.

# Usage: do_malloc_test <test number> <options...>
#
# The first argument, <test number>, is an integer used to name the
# tests executed by this proc. Options are as follows:
#
#     -tclprep          TCL script to run to prepare test.
#     -sqlprep          SQL script to run to prepare test.
#     -tclbody          TCL script to run with malloc failure simulation.
#     -sqlbody          TCL script to run with malloc failure simulation.
#     -cleanup          TCL script to run after the test.
#
# This command runs a series of tests to verify SQLite's ability
# to handle an out-of-memory condition gracefully. It is assumed
# that if this condition occurs a malloc() call will return a
# NULL pointer. Linux, for example, doesn't do that by default. See
# the "BUGS" section of malloc(3).
#
# Each iteration of a loop, the TCL commands in any argument passed
# to the -tclbody switch, followed by the SQL commands in any argument
# passed to the -sqlbody switch are executed. Each iteration the
# Nth call to sqliteMalloc() is made to fail, where N is increased
# each time the loop runs starting from 1. When all commands execute
# successfully, the loop ends.
#
proc do_malloc_test {tn args} {
  array unset ::mallocopts 
  array set ::mallocopts $args

  set ::go 1
  for {set ::n 1} {$::go && $::n < 50000} {incr ::n} {
    do_test shared_malloc-$tn.$::n {

      # Remove all traces of database files test.db and test2.db from the files
      # system. Then open (empty database) "test.db" with the handle [db].
      # 
      sqlite_malloc_fail 0
      catch {db close} 
      catch {file delete -force test.db}
      catch {file delete -force test.db-journal}
      catch {file delete -force test2.db}
      catch {file delete -force test2.db-journal}
      catch {sqlite3 db test.db} 
      set ::DB [sqlite3_connection_pointer db]

      # Execute any -tclprep and -sqlprep scripts.
      #
      if {[info exists ::mallocopts(-tclprep)]} {
        eval $::mallocopts(-tclprep)
      }
      if {[info exists ::mallocopts(-sqlprep)]} {
        execsql $::mallocopts(-sqlprep)
      }

      # Now set the ${::n}th malloc() to fail and execute the -tclbody and
      # -sqlbody scripts.
      #
      sqlite_malloc_fail $::n
      set ::mallocbody {}
      if {[info exists ::mallocopts(-tclbody)]} {
        append ::mallocbody "$::mallocopts(-tclbody)\n"
      }
      if {[info exists ::mallocopts(-sqlbody)]} {
        append ::mallocbody "db eval {$::mallocopts(-sqlbody)}"
      }
      set v [catch $::mallocbody msg]

      set leftover [lindex [sqlite_malloc_stat] 2]
      if {$leftover>0} {
        if {$leftover>1} {puts "\nLeftover: $leftover\nReturn=$v  Message=$msg"}
        set ::go 0
        if {$v} {
          puts "\nError message returned: $msg"
        } else {
          set v {1 1}
        }
      } else {
        set v2 [expr {$msg=="" || $msg=="out of memory"}]
        if {!$v2} {puts "\nError message returned: $msg"}
        lappend v $v2
      }
    } {1 1}

    sqlite_malloc_fail 0
    if {[info exists ::mallocopts(-cleanup)]} {
      catch [list uplevel #0 $::mallocopts(-cleanup)] msg
    }
  }
  unset ::mallocopts
}


do_ioerr_test shared_ioerr-1 -tclprep {
  sqlite3 db2 test.db
  execsql {
    PRAGMA read_uncommitted = 1;
    CREATE TABLE t1(a,b,c);
    BEGIN;
    SELECT * FROM sqlite_master;
  } db2
} -sqlbody {
  SELECT * FROM sqlite_master;
  INSERT INTO t1 VALUES(1,2,3);
  BEGIN TRANSACTION;
  INSERT INTO t1 VALUES(1,2,3);
  INSERT INTO t1 VALUES(4,5,6);
  ROLLBACK;
  SELECT * FROM t1;
  BEGIN TRANSACTION;
  INSERT INTO t1 VALUES(1,2,3);
  INSERT INTO t1 VALUES(4,5,6);
  COMMIT;
  SELECT * FROM t1;
  DELETE FROM t1 WHERE a<100;
} -cleanup {
  do_test shared_ioerr-1.$n.cleanup.1 {
    set res [catchsql {
      SELECT * FROM t1;
    } db2]
    set possible_results [list            \
      "1 {disk I/O error}"                \
      "0 {1 2 3}"                         \
      "0 {1 2 3 1 2 3 4 5 6}"             \
      "0 {1 2 3 1 2 3 4 5 6 1 2 3 4 5 6}" \
      "0 {}"                              \
    ]
    set rc [expr [lsearch -exact $possible_results $res] >= 0]
    if {$rc != 1} {
      puts ""
      puts "Result: $res"
    }
    set rc
  } {1}
  db2 close
}

do_ioerr_test shared_ioerr-2 -tclprep {
  sqlite3 db2 test.db
  execsql {
    PRAGMA read_uncommitted = 1;
    BEGIN;
    CREATE TABLE t1(a, b);
    INSERT INTO t1(oid) VALUES(NULL);
    INSERT INTO t1(oid) SELECT NULL FROM t1;
    INSERT INTO t1(oid) SELECT NULL FROM t1;
    INSERT INTO t1(oid) SELECT NULL FROM t1;
    INSERT INTO t1(oid) SELECT NULL FROM t1;
    INSERT INTO t1(oid) SELECT NULL FROM t1;
    INSERT INTO t1(oid) SELECT NULL FROM t1;
    INSERT INTO t1(oid) SELECT NULL FROM t1;
    INSERT INTO t1(oid) SELECT NULL FROM t1;
    INSERT INTO t1(oid) SELECT NULL FROM t1;
    INSERT INTO t1(oid) SELECT NULL FROM t1;
    UPDATE t1 set a = oid, b = 'abcdefghijklmnopqrstuvwxyz0123456789';
    CREATE INDEX i1 ON t1(a);
    COMMIT;
    BEGIN;
    SELECT * FROM sqlite_master;
  } db2
} -tclbody {
  set ::residx 0
  execsql {DELETE FROM t1 WHERE 0 = (a % 2);}
  incr ::residx

  # When this transaction begins the table contains 512 entries. The
  # two statements together add 512+146 more if it succeeds. 
  # (1024/7==146)
  execsql {BEGIN;}
  execsql {INSERT INTO t1 SELECT a+1, b FROM t1;}
  execsql {INSERT INTO t1 SELECT 'string' || a, b FROM t1 WHERE 0 = (a%7);}
  execsql {COMMIT;}

  incr ::residx
} -cleanup {
  do_test shared_ioerr-2.$n.cleanup.1 {
    set res [catchsql {
      SELECT max(a), min(a), count(*) FROM (SELECT a FROM t1 order by a);
    } db2]
    set possible_results [list \
      {0 {1024 1 1024}}        \
      {0 {1023 1 512}}         \
      {0 {string994 1 1170}}   \
    ]
    set idx [lsearch -exact $possible_results $res]
    set success [expr {$idx==$::residx || $res=="1 {disk I/O error}"}]
    if {!$success} {
      puts ""
      puts "Result: \"$res\" ($::residx)"
    }
    set success
  } {1}
  db2 close
}

# This test is designed to provoke an IO error when a cursor position is
# "saved" (because another cursor is going to modify the underlying table). 
# 
do_ioerr_test shared_ioerr-3 -tclprep {
  sqlite3 db2 test.db
  execsql {
    PRAGMA read_uncommitted = 1;
    PRAGMA cache_size = 10;
    BEGIN;
    CREATE TABLE t1(a, b, UNIQUE(a, b));
  } db2
  for {set i 0} {$i < 200} {incr i} {
    set a [string range [string repeat "[format %03d $i]." 5] 0 end-1]

    set b [string repeat $i 2000]
    execsql {INSERT INTO t1 VALUES($a, $b)} db2
  }
  execsql {COMMIT} db2
  set ::DB2 [sqlite3_connection_pointer db2]
  set ::STMT [sqlite3_prepare $::DB2 "SELECT a FROM t1 ORDER BY a" -1 DUMMY]
  sqlite3_step $::STMT       ;# Cursor points at 000.000.000.000
  sqlite3_step $::STMT       ;# Cursor points at 001.001.001.001

} -tclbody {
  execsql {
    BEGIN;
    INSERT INTO t1 VALUES('201.201.201.201.201', NULL);
    UPDATE t1 SET a = '202.202.202.202.202' WHERE a LIKE '201%';
    COMMIT;
  }
} -cleanup {
  do_test shared_ioerr-3.$n.cleanup.1 {
    sqlite3_step $::STMT
  } {SQLITE_ROW}
  do_test shared_ioerr-3.$n.cleanup.2 {
    sqlite3_column_text $::STMT 0
  } {002.002.002.002.002}
  do_test shared_ioerr-3.$n.cleanup.3 {
    sqlite3_finalize $::STMT
  } {SQLITE_OK}
# db2 eval {select * from sqlite_master}
  db2 close
}

# Only run these tests if memory debugging is turned on.
#
if {[info command sqlite_malloc_stat]==""} {
   puts "Skipping malloc tests: not compiled with -DSQLITE_MEMDEBUG..."
   db close
   sqlite3_enable_shared_cache $::enable_shared_cache
   finish_test
   return
}

# Provoke a malloc() failure when a cursor position is being saved. This
# only happens with index cursors (because they malloc() space to save the
# current key value). It does not happen with tables, because an integer
# key does not require a malloc() to store. 
#
# The library should return an SQLITE_NOMEM to the caller. The query that
# owns the cursor (the one for which the position is not saved) should
# continue unaffected.
# 
do_malloc_test 4 -tclprep {
  sqlite3 db2 test.db
  execsql {
    PRAGMA read_uncommitted = 1;
    BEGIN;
    CREATE TABLE t1(a, b, UNIQUE(a, b));
  } db2
  for {set i 0} {$i < 5} {incr i} {
    set a [string repeat $i 10]
    set b [string repeat $i 2000]
    execsql {INSERT INTO t1 VALUES($a, $b)} db2
  }
  execsql {COMMIT} db2
  set ::DB2 [sqlite3_connection_pointer db2]
  set ::STMT [sqlite3_prepare $::DB2 "SELECT a FROM t1 ORDER BY a" -1 DUMMY]
  sqlite3_step $::STMT       ;# Cursor points at 0000000000
  sqlite3_step $::STMT       ;# Cursor points at 1111111111
} -tclbody {
  execsql {
    INSERT INTO t1 VALUES(6, NULL);
  }
} -cleanup {
  do_test shared_malloc-4.$::n.cleanup.1 {
    sqlite3_step $::STMT
  } {SQLITE_ROW}
  do_test shared_malloc-4.$::n.cleanup.2 {
    sqlite3_column_text $::STMT 0
  } {2222222222}
  do_test shared_malloc-4.$::n.cleanup.3 {
    sqlite3_finalize $::STMT
  } {SQLITE_OK}
# db2 eval {select * from sqlite_master}
  db2 close
}

do_malloc_test 5 -tclbody {
  sqlite3 dbX test.db
  sqlite3 dbY test.db
  dbX close
  dbY close
} -cleanup {
  catch {dbX close}
  catch {dbY close}
}

catch {db close}
sqlite3_enable_shared_cache $::enable_shared_cache
finish_test