Module: RubySync::Connectors::MemoryChangeTracking

Included in:
MemoryConnector
Defined in:
lib/ruby_sync/connectors/memory_change_tracking.rb

Overview

When included by a connector, tracks changes to the connector using a dbm database of the form path:digest. Digest is a MD5 hash of the record so we can tell if the record has changed. We can’t, however, tell how the record has changed so change events generated will be for the entire record.

Instance Method Summary collapse

Instance Method Details

#delete_from_mirror(path) ⇒ Object 



75
76
77
 
# File 'lib/ruby_sync/connectors/memory_change_tracking.rb', line 75

def delete_from_mirror path
  shadow.delete(path.to_s)
end

#digest(o) ⇒ Object 



67
68
69
 
# File 'lib/ruby_sync/connectors/memory_change_tracking.rb', line 67

def digest(o)
  Digest::MD5.hexdigest(o.to_yaml)
end

#each_change ⇒ Object

Subclasses MAY override this to interface with the external system and generate an event for every change that affects items within the scope of this connector.

The default behaviour is to compare a hash of each entry in the database with a stored hash of its previous value and generate add, modify and delete events appropriately. This is normally a very inefficient way to operate so overriding this method is highly recommended if you can detect changes in a more efficient manner.

This method will be called repeatedly until the connector is stopped.



43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
 
# File 'lib/ruby_sync/connectors/memory_change_tracking.rb', line 43

def each_change
  # scan existing entries to see if any new or modified
  each_entry do |path, entry|
    digest = digest(entry)
    unless stored_digest = shadow[path.to_s] and digest == stored_digest
	operations = create_operations_for(entry)
	yield RubySync::Event.add(self, path, nil, operations) 
	shadow[path.to_s] = digest
    end
  end
        
  # scan shadow to find deleted
  shadow.each do |key, stored_hash|
    unless self[key]
	yield RubySync::Event.delete(self, key)
	shadow.delete key
	if is_vault? and @pipeline
 association = association_for @pipeline.association_context, key
 remove_association association
	end
    end
  end
end

#remove_mirror ⇒ Object 



71
72
73
 
# File 'lib/ruby_sync/connectors/memory_change_tracking.rb', line 71

def remove_mirror
  @shadow = nil
end

#shadow ⇒ Object 



27
28
29
 
# File 'lib/ruby_sync/connectors/memory_change_tracking.rb', line 27

def shadow
  @shadow ||= {}
end

#update_mirror(path) ⇒ Object 



79
80
81
82
 
# File 'lib/ruby_sync/connectors/memory_change_tracking.rb', line 79

def update_mirror path
  entry = self[path.to_s]
  shadow[path.to_s] = digest(entry)
end