Add a changeset cache to stop us looking up the same changeset over

[rails.git] / app / models / changeset.rb

diff --git a/app/models/changeset.rb b/app/models/changeset.rb
index 047569dca5cf15db682c9c1fbd8fe72a85b3a942..fa2d556b10c00195a20d5f8670224a22475ebb7b 100644 (file)
--- a/app/models/changeset.rb
+++ b/app/models/changeset.rb
@@ -12,30 +12,60 @@ class Changeset < ActiveRecord::Base
   has_many :old_ways
   has_many :old_relations
   
-  validates_presence_of :user_id, :created_at
-  validates_inclusion_of :open, :in => [ true, false ]
-  
+  validates_presence_of :id, :on => :update
+  validates_presence_of :user_id, :created_at, :closed_at, :num_changes
+  validates_uniqueness_of :id
+  validates_numericality_of :id, :on => :update, :integer_only => true
+  validates_numericality_of :min_lat, :max_lat, :min_lon, :max_lat, :allow_nil => true, :integer_only => true
+  validates_numericality_of :user_id,  :integer_only => true
+  validates_numericality_of :num_changes, :integer_only => true, :greater_than_or_equal_to => 0
+  validates_associated :user
+
   # over-expansion factor to use when updating the bounding box
   EXPAND = 0.1
 
+  # maximum number of elements allowed in a changeset
+  MAX_ELEMENTS = 50000
+
+  # maximum time a changeset is allowed to be open for.
+  MAX_TIME_OPEN = 1.day
+
+  # idle timeout increment, one hour seems reasonable.
+  IDLE_TIMEOUT = 1.hour
+
   # Use a method like this, so that we can easily change how we
   # determine whether a changeset is open, without breaking code in at 
   # least 6 controllers
   def is_open?
-    return open
+    # a changeset is open (that is, it will accept further changes) when
+    # it has not yet run out of time and its capacity is small enough.
+    # note that this may not be a hard limit - due to timing changes and
+    # concurrency it is possible that some changesets may be slightly 
+    # longer than strictly allowed or have slightly more changes in them.
+    return ((closed_at > Time.now.getutc) and (num_changes <= MAX_ELEMENTS))
   end
 
+  def set_closed_time_now
+    if is_open?
+      self.closed_at = Time.now.getutc
+    end
+  end
+  
   def self.from_xml(xml, create=false)
     begin
-      p = XML::Parser.new
-      p.string = xml
+      p = XML::Parser.string(xml)
       doc = p.parse
 
       cs = Changeset.new
 
       doc.find('//osm/changeset').each do |pt|
         if create
-          cs.created_at = Time.now
+          cs.created_at = Time.now.getutc
+          # initial close time is 1h ahead, but will be increased on each
+          # modification.
+          cs.closed_at = cs.created_at + IDLE_TIMEOUT
+          # initially we have no changes in a changeset
+          cs.num_changes = 0
         end
 
         pt.find('tag').each do |tag|
@@ -55,6 +85,10 @@ class Changeset < ActiveRecord::Base
   def bbox
     @bbox ||= [ min_lon, min_lat, max_lon, max_lat ]
   end
+  
+  def has_valid_bbox?
+    not bbox.include? nil
+  end
 
   ##
   # expand the bounding box to include the given bounding box. also, 
@@ -78,6 +112,14 @@ class Changeset < ActiveRecord::Base
     self.min_lon, self.min_lat, self.max_lon, self.max_lat = @bbox
   end
 
+  ##
+  # the number of elements is also passed in so that we can ensure that
+  # a single changeset doesn't contain too many elements. this, of course,
+  # destroys the optimisation described in the bbox method above.
+  def add_changes!(elements)
+    self.num_changes += elements
+  end
+
   def tags_as_hash
     return tags
   end
@@ -102,13 +144,19 @@ class Changeset < ActiveRecord::Base
   end
 
   def save_with_tags!
-    t = Time.now
+    t = Time.now.getutc
 
     # do the changeset update and the changeset tags update in the
     # same transaction to ensure consistency.
     Changeset.transaction do
-      # fixme update modified_at time?
-      # FIXME there is no modified_at time, should it be added
+      # set the auto-close time to be one hour in the future unless
+      # that would make it more than 24h long, in which case clip to
+      # 24h, as this has been decided is a reasonable time limit.
+      if (closed_at - created_at) > (MAX_TIME_OPEN - IDLE_TIMEOUT)
+        self.closed_at = created_at + MAX_TIME_OPEN
+      else
+        self.closed_at = Time.now.getutc + IDLE_TIMEOUT
+      end
       self.save!
 
       tags = self.tags
@@ -155,7 +203,8 @@ class Changeset < ActiveRecord::Base
     end
     
     el1['created_at'] = self.created_at.xmlschema
-    el1['open'] = self.open.to_s
+    el1['closed_at'] = self.closed_at.xmlschema unless is_open?
+    el1['open'] = is_open?.to_s
 
     el1['min_lon'] = (bbox[0].to_f / GeoRecord::SCALE).to_s unless bbox[0].nil?
     el1['min_lat'] = (bbox[1].to_f / GeoRecord::SCALE).to_s unless bbox[1].nil?
@@ -176,12 +225,12 @@ class Changeset < ActiveRecord::Base
   def update_from(other, user)
     # ensure that only the user who opened the changeset may modify it.
     unless user.id == self.user_id 
-      raise OSM::APIUserChangesetMismatchError 
+      raise OSM::APIUserChangesetMismatchError.new
     end
     
     # can't change a closed changeset
-    unless open
-      raise OSM::APIChangesetAlreadyClosedError
+    unless is_open?
+      raise OSM::APIChangesetAlreadyClosedError.new(self)
     end
 
     # copy the other's tags