Please find attached my revised patch for adding online backup support to DBD::SQLite.

This time it includes a unit test, and uses the sqlite_ prefix for functions, and uses the install_method() system from DBI to provide those functions.

I note that I needed to patch my local DBI.pm to include:

    sqlite_  => { class => 'DBD::SQLite' }

So I'm not sure what effect that will have on backward compatibility with current stable versions of DBI?

-Toby
Patch to add support for SQLite's Online Backup functions.

I intend to improve this to use the "stepping" online backup method at some
point, which is friendlier for concurrent database users. However the public
API should remain the same, and I figure people might like to play with the
system for now.

Signed off by Toby Corkindale <[email protected]>

 Changes              |    1 +
 SQLite.xs            |   19 ++++++++++++++++
 dbdimp.c             |   56 +++++++++++++++++++++++++++++++++++++++++++++++++
 dbdimp.h             |    2 +
 lib/DBD/SQLite.pm    |   16 ++++++++++++++
 t/35_online_backup.t |   57 ++++++++++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 151 insertions(+), 0 deletions(-)

diff --git a/Changes b/Changes
index 4998374..2224f90 100644
--- a/Changes
+++ b/Changes
@@ -9,6 +9,7 @@ Changes for Perl extension DBD-SQLite
     - Added some explanation and workarounds for a SQL that
       compares a return value of a function with a numeric bind
       value (ISHIGAKI)
+    - Added access to Online Backup functionality. (TJC)
 
 1.25 Thu 23 Apr 2009
     - Amalgamation conversion turned out to be quicker than expected.
diff --git a/SQLite.xs b/SQLite.xs
index fda00aa..8e9d0a6 100644
--- a/SQLite.xs
+++ b/SQLite.xs
@@ -92,6 +92,25 @@ busy_timeout(dbh, timeout=0)
   OUTPUT:
     RETVAL
 
+int
+sqlite_backup_from_file(dbh, filename)
+  SV *dbh
+  char *filename
+  CODE:
+    RETVAL = _sqlite_backup_from_file(aTHX_ dbh, filename);
+  OUTPUT:
+    RETVAL
+
+int
+sqlite_backup_to_file(dbh, filename)
+  SV *dbh
+  char *filename
+  CODE:
+    RETVAL = _sqlite_backup_to_file(aTHX_ dbh, filename);
+  OUTPUT:
+    RETVAL
+
+
 MODULE = DBD::SQLite          PACKAGE = DBD::SQLite::st
 
 PROTOTYPES: DISABLE
diff --git a/dbdimp.c b/dbdimp.c
index 89a531e..cce3e30 100644
--- a/dbdimp.c
+++ b/dbdimp.c
@@ -139,6 +139,62 @@ dbd_set_sqlite3_busy_timeout (pTHX_ SV *dbh, int timeout )
   return imp_dbh->timeout;
 }
 
+/* Accesses the SQLite Online Backup API, and fills the currently loaded
+ * database from the passed filename.
+ * Usual usage of this would be when you're operating on the :memory:
+ * special database connection and want to copy it in from a real db.
+ */
+int
+_sqlite_backup_from_file(pTHX_ SV *dbh, char *filename)
+{
+    int rc;
+    sqlite3 *pFrom;
+    sqlite3_backup *pBackup;
+
+    D_imp_dbh(dbh);
+
+    rc = sqlite3_open(filename, &pFrom);
+    if (rc==SQLITE_OK) {
+
+        pBackup = sqlite3_backup_init(imp_dbh->db, "main", pFrom, "main");
+        if (pBackup) {
+            (void)sqlite3_backup_step(pBackup, -1);
+            (void)sqlite3_backup_finish(pBackup);
+        }
+        rc = sqlite3_errcode(imp_dbh->db);
+        (void)sqlite3_close(pFrom);
+    }
+    return rc;
+}
+
+/* Accesses the SQLite Online Backup API, and copies the currently loaded
+ * database into the passed filename.
+ * Usual usage of this would be when you're operating on the :memory:
+ * special database connection, and want to back it up to an on-disk file.
+ */
+int
+_sqlite_backup_to_file(pTHX_ SV *dbh, char *filename)
+{
+    int rc;
+    sqlite3 *pTo;
+    sqlite3_backup *pBackup;
+
+    D_imp_dbh(dbh);
+
+    rc = sqlite3_open(filename, &pTo);
+    if (rc==SQLITE_OK) {
+
+        pBackup = sqlite3_backup_init(pTo, "main", imp_dbh->db, "main");
+        if (pBackup) {
+            (void)sqlite3_backup_step(pBackup, -1);
+            (void)sqlite3_backup_finish(pBackup);
+        }
+        rc = sqlite3_errcode(pTo);
+        (void)sqlite3_close(pTo);
+    }
+    return rc;
+}
+
 int
 sqlite_db_disconnect (SV *dbh, imp_dbh_t *imp_dbh)
 {
diff --git a/dbdimp.h b/dbdimp.h
index 78f7c5e..dea1bcd 100644
--- a/dbdimp.h
+++ b/dbdimp.h
@@ -79,6 +79,8 @@ void sqlite3_db_progress_handler(pTHX_ SV *dbh, int n_opcodes, SV *handler);
 void sqlite_st_reset(pTHX_ SV *sth );
 int sqlite_bind_col( SV *sth, imp_sth_t *imp_sth, SV *col, SV *ref, IV sql_type, SV *attribs );
 int dbd_set_sqlite3_busy_timeout (pTHX_ SV *dbh, int timeout );
+int _sqlite_backup_from_file(pTHX_ SV *dbh, char *filename);
+int _sqlite_backup_to_file(pTHX_ SV *dbh, char *filename);
 
 #ifdef SvUTF8_on
 
diff --git a/lib/DBD/SQLite.pm b/lib/DBD/SQLite.pm
index 3e6219a..4adb72d 100644
--- a/lib/DBD/SQLite.pm
+++ b/lib/DBD/SQLite.pm
@@ -98,6 +98,10 @@ sub connect {
         $attr->{Warn} = 0;
     }
 
+    # Install online backup private methods:
+    DBD::SQLite::db->install_method('sqlite_backup_from_file', {});
+    DBD::SQLite::db->install_method('sqlite_backup_to_file', {});
+
     return $dbh;
 }
 
@@ -723,6 +727,18 @@ progress handler.
 
 =back
 
+=head2 $dbh->sqlite_backup_from_file( $filename )
+
+This method accesses the SQLite Online Backup API, and will take a backup of
+the named database file, copying it to, and overwriting, your current database
+connection. This can be particularly handy if your current connection is to the
+special :memory: database, and you wish to populate it from an existing DB.
+
+=head2 $dbh->sqlite_backup_to_file( $filename )
+
+This method accesses the SQLite Online Backup API, and will take a backup of
+the currently connected database, and write it out to the named file.
+
 =head1 BLOBS
 
 As of version 1.11, blobs should "just work" in SQLite as text columns.
diff --git a/t/35_online_backup.t b/t/35_online_backup.t
new file mode 100644
index 0000000..37dea7b
--- /dev/null
+++ b/t/35_online_backup.t
@@ -0,0 +1,57 @@
+#!/usr/bin/perl
+use strict;
+use warnings;
+
+use Test::More tests => 4;
+use t::lib::Test;
+use DBI;
+
+# Connect to the test db and add some stuff:
+my $foo = connect_ok( RaiseError => 1 );
+$foo->do(
+    'CREATE TABLE online_backup_test( id INTEGER PRIMARY KEY, foo INTEGER )'
+);
+$foo->do("INSERT INTO online_backup_test (foo) VALUES ($$)");
+
+# That should be in the "foo" database on disk now, so disconnect and try to
+# back it up:
+
+$foo->disconnect;
+
+my $dbh = DBI->connect(
+    'dbi:SQLite:dbname=:memory:',
+    undef, undef,
+    { RaiseError => 1 }
+);
+
+$dbh->sqlite_backup_from_file('foo');
+
+{
+    my ($count) = $dbh->selectrow_array(
+        "SELECT count(foo) FROM online_backup_test WHERE foo=$$"
+    );
+    is($count, 1, "Found our process ID in backed-up table");
+}
+
+# Add more data then attempt to copy it back to file:
+$dbh->do(
+    'CREATE TABLE online_backup_test2 ( id INTEGER PRIMARY KEY, foo INTEGER )'
+);
+$dbh->do("INSERT INTO online_backup_test2 (foo) VALUES ($$)");
+
+# backup to file (foo):
+$dbh->sqlite_backup_to_file('foo');
+
+$dbh->disconnect;
+
+# Reconnect to foo db and check data made it over:
+{
+    my $foo = connect_ok( RaiseError => 1 );
+
+    my ($count) = $foo->selectrow_array(
+        "SELECT count(foo) FROM online_backup_test2 WHERE foo=$$"
+    );
+    is($count, 1, "Found our process ID in table back on disk");
+
+    $foo->disconnect;
+}
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