Padre::Autosave






Padre::Autosave − auto−save and recovery mechanism for Padre


  my $autosave = Padre:Autosave−>new( db => 'path/to/database' );
  $autosave−>save_file( $path, $type, $data, $timestamp ) = @_;



The following is just a plan that is currently shelved as
some people on the Padre development list think this is not
necessary and one should use a real version control for this
anyway.

     So I leave it here for now, for future exploration.

     I’d like to provide auto‐save with some history and
recovery service.

     While I am writing this for Padre I’ll make the code
separate so others can use it.

     An SQLite database will be used for this but
theoretically any database could be used. Event plain file
system.

     Basically this will provide a versioned file system
with metadata and automatic cleanup.

     Besides the content of the file we need to save some
meta data:

path to the file will be the unique identifier

timestamp

type of save (initial, auto‐save, user initiated save,
    external)

     When opening a file for the first time it is saved in
the database.(initial)

     Every N seconds files that are not currently in "saved"
situation are auto‐saved in the database making sure that
they are only saved if they differ from the previous state.
(auto‐save)

     Evey time a file is saved it is also saved to the
database. (user initiated save) Before reloading a file we
auto‐save it. (auto‐save)

     Every time we notice that a file was changed on the
disk if the user decides to overwrite it we also save the
(external) changed file.










                             ‐2‐


     Before auto‐saving a file we make sure it has not
changed since the last auto‐save.

     In order to make sure the database does not get too big
we setup a cleaning mechanism that is executed once in a
while.  There might be several options but for now: 1) Every
entry older than N days will be deleted.

     Based on the database we’ll be able to provide the user
recovery in case of crash or accidental overwrite.

     When opening padre we should check if there are files
in the database that the last save was not a user initiated
save and offer recovery.

     When opening a file we should also check how is it
related to the last save in the database.

     For buffers that were never saved and so have no file
names we should have some internal identifier in Padre and
use that for the auto‐save till the first user initiated
save.

     The same mechanism will be really useful when we start
providing remote editing. Then a file is identified by its
URI ( ftp://machine/path/to/file or
scp://machine/path/to/file )

       my @types = qw(initial, autosave, usersave, external);

  sub save_data {
      my ($path, $timestamp, $type, $data) = @_;
  }