source: subversion/sites/rails_port/app/models/changeset.rb @ 17073

Revision 17073, 7.6 KB checked in by zere, 5 years ago (diff)

Fixes bug #2152 by preventing over-expansion of bboxes beyond the world range.

Line 
1class Changeset < ActiveRecord::Base
2  require 'xml/libxml'
3
4  belongs_to :user
5
6  has_many :changeset_tags, :foreign_key => 'id'
7 
8  has_many :nodes
9  has_many :ways
10  has_many :relations
11  has_many :old_nodes
12  has_many :old_ways
13  has_many :old_relations
14 
15  validates_presence_of :id, :on => :update
16  validates_presence_of :user_id, :created_at, :closed_at, :num_changes
17  validates_uniqueness_of :id
18  validates_numericality_of :id, :on => :update, :integer_only => true
19  validates_numericality_of :min_lat, :max_lat, :min_lon, :max_lat, :allow_nil => true, :integer_only => true
20  validates_numericality_of :user_id,  :integer_only => true
21  validates_numericality_of :num_changes, :integer_only => true, :greater_than_or_equal_to => 0
22  validates_associated :user
23
24  # over-expansion factor to use when updating the bounding box
25  EXPAND = 0.1
26
27  # maximum number of elements allowed in a changeset
28  MAX_ELEMENTS = 50000
29
30  # maximum time a changeset is allowed to be open for.
31  MAX_TIME_OPEN = 1.day
32
33  # idle timeout increment, one hour seems reasonable.
34  IDLE_TIMEOUT = 1.hour
35
36  # Use a method like this, so that we can easily change how we
37  # determine whether a changeset is open, without breaking code in at
38  # least 6 controllers
39  def is_open?
40    # a changeset is open (that is, it will accept further changes) when
41    # it has not yet run out of time and its capacity is small enough.
42    # note that this may not be a hard limit - due to timing changes and
43    # concurrency it is possible that some changesets may be slightly
44    # longer than strictly allowed or have slightly more changes in them.
45    return ((closed_at > Time.now.getutc) and (num_changes <= MAX_ELEMENTS))
46  end
47
48  def set_closed_time_now
49    if is_open?
50      self.closed_at = Time.now.getutc
51    end
52  end
53 
54  def self.from_xml(xml, create=false)
55    begin
56      p = XML::Parser.string(xml)
57      doc = p.parse
58
59      cs = Changeset.new
60
61      doc.find('//osm/changeset').each do |pt|
62        if create
63          cs.created_at = Time.now.getutc
64          # initial close time is 1h ahead, but will be increased on each
65          # modification.
66          cs.closed_at = cs.created_at + IDLE_TIMEOUT
67          # initially we have no changes in a changeset
68          cs.num_changes = 0
69        end
70
71        pt.find('tag').each do |tag|
72          cs.add_tag_keyval(tag['k'], tag['v'])
73        end
74      end
75    rescue Exception => ex
76      cs = nil
77    end
78
79    return cs
80  end
81
82  ##
83  # returns the bounding box of the changeset. it is possible that some
84  # or all of the values will be nil, indicating that they are undefined.
85  def bbox
86    @bbox ||= [ min_lon, min_lat, max_lon, max_lat ]
87  end
88 
89  def has_valid_bbox?
90    not bbox.include? nil
91  end
92 
93  ##
94  # returns area of the changset bbox as a rough comparitive quantity for use of changset displays
95  def area
96     if has_valid_bbox?
97             (max_lon - min_lon) * (max_lat - min_lat)
98     else
99             0
100     end
101  end
102
103  ##
104  # expand the bounding box to include the given bounding box. also,
105  # expand a little bit more in the direction of the expansion, so that
106  # further expansions may be unnecessary. this is an optimisation
107  # suggested on the wiki page by kleptog.
108  def update_bbox!(array)
109    # ensure that bbox is cached and has no nils in it. if there are any
110    # nils, just use the bounding box update to write over them.
111    @bbox = bbox.zip(array).collect { |a, b| a.nil? ? b : a }
112
113    # FIXME - this looks nasty and violates DRY... is there any prettier
114    # way to do this?
115    @bbox[0] = [-180 * SCALE, array[0] + EXPAND * (@bbox[0] - @bbox[2])].max if array[0] < @bbox[0]
116    @bbox[1] = [ -90 * SCALE, array[1] + EXPAND * (@bbox[1] - @bbox[3])].max if array[1] < @bbox[1]
117    @bbox[2] = [ 180 * SCALE, array[2] + EXPAND * (@bbox[2] - @bbox[0])].min if array[2] > @bbox[2]
118    @bbox[3] = [  90 * SCALE, array[3] + EXPAND * (@bbox[3] - @bbox[1])].min if array[3] > @bbox[3]
119
120    # update active record. rails 2.1's dirty handling should take care of
121    # whether this object needs saving or not.
122    self.min_lon, self.min_lat, self.max_lon, self.max_lat = @bbox
123  end
124
125  ##
126  # the number of elements is also passed in so that we can ensure that
127  # a single changeset doesn't contain too many elements. this, of course,
128  # destroys the optimisation described in the bbox method above.
129  def add_changes!(elements)
130    self.num_changes += elements
131  end
132
133  def tags_as_hash
134    return tags
135  end
136
137  def tags
138    unless @tags
139      @tags = {}
140      self.changeset_tags.each do |tag|
141        @tags[tag.k] = tag.v
142      end
143    end
144    @tags
145  end
146
147  def tags=(t)
148    @tags = t
149  end
150
151  def add_tag_keyval(k, v)
152    @tags = Hash.new unless @tags
153    @tags[k] = v
154  end
155
156  def save_with_tags!
157    # do the changeset update and the changeset tags update in the
158    # same transaction to ensure consistency.
159    Changeset.transaction do
160      self.save!
161
162      tags = self.tags
163      ChangesetTag.delete_all(['id = ?', self.id])
164
165      tags.each do |k,v|
166        tag = ChangesetTag.new
167        tag.k = k
168        tag.v = v
169        tag.id = self.id
170        tag.save!
171      end
172    end
173  end
174
175  ##
176  # set the auto-close time to be one hour in the future unless
177  # that would make it more than 24h long, in which case clip to
178  # 24h, as this has been decided is a reasonable time limit.
179  def before_save
180    if self.is_open?
181      if (closed_at - created_at) > (MAX_TIME_OPEN - IDLE_TIMEOUT)
182        self.closed_at = created_at + MAX_TIME_OPEN
183      else
184        self.closed_at = Time.now.getutc + IDLE_TIMEOUT
185      end
186    end
187  end
188 
189  def to_xml
190    doc = OSM::API.new.get_xml_doc
191    doc.root << to_xml_node()
192    return doc
193  end
194 
195  def to_xml_node(user_display_name_cache = nil)
196    el1 = XML::Node.new 'changeset'
197    el1['id'] = self.id.to_s
198
199    user_display_name_cache = {} if user_display_name_cache.nil?
200
201    if user_display_name_cache and user_display_name_cache.key?(self.user_id)
202      # use the cache if available
203    elsif self.user.data_public?
204      user_display_name_cache[self.user_id] = self.user.display_name
205    else
206      user_display_name_cache[self.user_id] = nil
207    end
208
209    el1['user'] = user_display_name_cache[self.user_id] unless user_display_name_cache[self.user_id].nil?
210    el1['uid'] = self.user_id.to_s if self.user.data_public?
211
212    self.tags.each do |k,v|
213      el2 = XML::Node.new('tag')
214      el2['k'] = k.to_s
215      el2['v'] = v.to_s
216      el1 << el2
217    end
218   
219    el1['created_at'] = self.created_at.xmlschema
220    el1['closed_at'] = self.closed_at.xmlschema unless is_open?
221    el1['open'] = is_open?.to_s
222
223    el1['min_lon'] = (bbox[0].to_f / GeoRecord::SCALE).to_s unless bbox[0].nil?
224    el1['min_lat'] = (bbox[1].to_f / GeoRecord::SCALE).to_s unless bbox[1].nil?
225    el1['max_lon'] = (bbox[2].to_f / GeoRecord::SCALE).to_s unless bbox[2].nil?
226    el1['max_lat'] = (bbox[3].to_f / GeoRecord::SCALE).to_s unless bbox[3].nil?
227   
228    # NOTE: changesets don't include the XML of the changes within them,
229    # they are just structures for tagging. to get the osmChange of a
230    # changeset, see the download method of the controller.
231
232    return el1
233  end
234
235  ##
236  # update this instance from another instance given and the user who is
237  # doing the updating. note that this method is not for updating the
238  # bounding box, only the tags of the changeset.
239  def update_from(other, user)
240    # ensure that only the user who opened the changeset may modify it.
241    unless user.id == self.user_id
242      raise OSM::APIUserChangesetMismatchError.new
243    end
244   
245    # can't change a closed changeset
246    unless is_open?
247      raise OSM::APIChangesetAlreadyClosedError.new(self)
248    end
249
250    # copy the other's tags
251    self.tags = other.tags
252
253    save_with_tags!
254  end
255end
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