use uuids for guid generation

Changelog.md

 # Head
 
+## Change in guid generation
+
+This version will break federation to pods running on versions prior 0.1.1.0.
+
+Read more in [#4249](https://github.com/diaspora/diaspora/pull/4249) and [#4883](https://github.com/diaspora/diaspora/pull/4883)
+
 ## Refactor
 * Drop number of followers from tags page [#4717](https://github.com/diaspora/diaspora/issues/4717)
 * Remove some unused beta code [#4738](https://github.com/diaspora/diaspora/issues/4738)

Gemfile

@@ -50,6 +50,9 @@ gem 'fog',         '1.19.0'
 gem 'mini_magick', '3.7.0'
 gem 'remotipart',  '1.2.1'
 
+# GUID generation
+gem 'uuid', '2.3.7'
+
 # Localization
 
 gem 'http_accept_language', '1.0.2'

Gemfile.lock

@@ -223,6 +223,8 @@ GEM
       rb-fsevent (>= 0.9.3)
       rb-inotify (>= 0.9)
     lumberjack (1.0.4)
+    macaddr (1.6.1)
+      systemu (~> 2.5.0)
     mail (2.5.4)
       mime-types (~> 1.16)
       treetop (~> 1.4.8)
@@ -411,6 +413,7 @@ GEM
       activemodel (~> 3.0)
       railties (~> 3.0)
     subexec (0.2.3)
+    systemu (2.5.2)
     test_after_commit (0.2.2)
     thor (0.18.1)
     thread_safe (0.1.3)
@@ -435,8 +438,10 @@ GEM
       kgio (~> 2.6)
       rack
       raindrops (~> 0.7)
-    warden (1.2.3)
+    uuid (2.3.7)
+      macaddr (~> 1.0)
       rack (>= 1.0)
+    warden (1.2.3)
     webmock (1.16.1)
       addressable (>= 2.2.7)
       crack (>= 0.3.2)
@@ -532,6 +537,7 @@ DEPENDENCIES
   typhoeus (= 0.6.7)
   uglifier (= 2.1.2)
   unicorn (= 4.8.0)
+  uuid (= 2.3.7)
   webmock (= 1.16.1)
   will_paginate (= 3.0.5)
   zip-zip

config/initializers/sidekiq.rb

@@ -44,6 +44,9 @@ Sidekiq.configure_server do |config|
     ENV['DATABASE_URL'] = "#{database_url}?pool=#{AppConfig.environment.sidekiq.concurrency.get}"
     ActiveRecord::Base.establish_connection
   end
+  
+  # Make sure each Sidekiq process has its own sequence of UUIDs
+  UUID.generator.next_sequence
 end
 
 Sidekiq.configure_client do |config|

config/unicorn.rb

@@ -48,4 +48,7 @@ end
 after_fork do |server, worker|
   # If using preload_app, enable this line
   ActiveRecord::Base.establish_connection
+
+  # We don't generate uuids in the frontend, but let's be on the safe side
+  UUID.generator.next_sequence
 end

lib/diaspora/guid.rb

@@ -13,6 +13,6 @@ module Diaspora::Guid
 
   # @return [String] The model's guid.
   def set_guid
-    self.guid = SecureRandom.hex(8) if self.guid.blank?
+    self.guid = UUID.generate :compact if self.guid.blank?
   end
 end