Download/restores objects in parallel

[naoliv]

Could undelete download/restore objects in parallel?

JOSM:

Repository Root: http://josm.openstreetmap.de/svn
Build-Date: 2014-11-24 02:33:57
Last Changed Author: Don-vip
Revision: 7743
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Relative URL: ^/trunk
URL: http://josm.openstreetmap.de/svn/trunk
Last Changed Date: 2014-11-23 23:54:40 +0100 (Sun, 23 Nov 2014)
Last Changed Rev: 7743

Identification: JOSM/1.5 (7743 pt_BR) Linux Debian GNU/Linux testing (jessie)
Memory Usage: 247 MB / 8158 MB (137 MB allocated, but free)
Java version: 1.7.0_65, Oracle Corporation, OpenJDK 64-Bit Server VM
Java package: openjdk-7-jre:amd64-7u71-2.5.3-2
VM arguments: [-Dawt.useSystemAAFontSettings=on]
Dataset consistency test: No problems found

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- ImageryCache (30738)
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- SimplifyArea (30791)
- buildings_tools (30762)
- conflation (0.1.7)
- contourmerge (1012)
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- editgpx (30737)
- geotools (30762)
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- merge-overlap (30784)
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- pdfimport (30737)
- poly (30738)
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- scripting (30702)
- todo (29154)
- turnrestrictions (30762)
- undelete (30762)
- utilsplugin2 (30762)

[naoliv]

Ticket #11287 has been marked as a duplicate of this ticket.

[GerdP]

Maybe we should use multifetch api?
Let's assume we want to undelete three nodes n265801406 and n265801408
First api call would be
​https://api.openstreetmap.org/api/0.6/nodes?nodes=265801406,265801408
Answer:

<osm version="0.6" generator="CGImap 0.6.1 (1971 thorn-02.openstreetmap.org)"
copyright="OpenStreetMap and contributors" attribution="http://www.openstreetmap.org/copyright"
license="http://opendatacommons.org/licenses/odbl/1-0/">
  <node id="265801406" visible="false" version="10" changeset="40074957" timestamp="2016-06-16T19:08:28Z" user="Reino Baptista" uid="2820801" />
  <node id="265801408" visible="false" version="8" changeset="40074957" timestamp="2016-06-16T19:08:28Z" user="Reino Baptista" uid="2820801" />
</osm>

Now we know the versions of all nodes we want to undelete. n265801406 has version 10 and 265801408 has version 8
So the next api call would be like the first, but with explicit decremented versions:
​https://api.openstreetmap.org/api/0.6/nodes?nodes=265801406v9,265801408v7
Answer:

<osm version="0.6" generator="CGImap 0.6.1 (1977 thorn-02.openstreetmap.org)"
copyright="OpenStreetMap and contributors" attribution="http://www.openstreetmap.org/copyright"
license="http://opendatacommons.org/licenses/odbl/1-0/">
  <node id="265801406" visible="true" version="9" changeset="31851793" timestamp="2015-06-09T18:19:52Z" user="SilverKnight" uid="1692086" lat="41.6110476" lon="-8.8077179" />
  <node id="265801408" visible="true" version="7" changeset="26920648" timestamp="2014-11-21T02:40:17Z" user="ViriatoLusitano_import" uid="2330803" lat="41.6096789" lon="-8.8069574" />
</osm>

In this case we have all information that we need. In special cases we might have to crawl further back.

[GerdP]

@naoliv: maybe I got you wrong. I focussed on performance.
Not sure how it worked 5 years ago. You can undelete a list of objects, e.g. "n265801406 n265801408"
Did you mean this or is it about performance when undeleting a long list of objects?