Optimize hosts read

src/include/network/lan/address.rb

@@ -1546,7 +1546,7 @@ def AddressDialog
               Host.Update(
                 @hostname_initial,
                 Ops.get_string(@settings, "HOSTNAME", ""),
-                [Ops.get_string(@settings, "IPADDR", "")]
+                Ops.get_string(@settings, "IPADDR", "")
               )
             end
           end

src/lib/cfa/hosts.rb

@@ -0,0 +1,147 @@
+require "yast"
+require "yast2/target_file"
+
+require "cfa/base_model"
+require "cfa/matcher"
+require "cfa/augeas_parser"
+
+module CFA
+  class Hosts < BaseModel
+    PARSER = AugeasParser.new("hosts.lns")
+    PATH = "/etc/hosts".freeze
+    include Yast::Logger
+
+    def initialize(file_handler: nil)
+      super(PARSER, PATH, file_handler: file_handler)
+    end
+
+    def hosts
+      matcher = Matcher.new { |k,v| k =~ /^\d*$/ }
+      data.select(matcher).each_with_object({}) do |host, result|
+        entry = host[:value]
+        result[entry["ipaddr"]] ||= []
+        result[entry["ipaddr"]] << single_host_entry(entry)
+      end
+    end
+
+    def host(ip)
+      hosts = data.select(ip_matcher(ip))
+
+      hosts.map do |host|
+        single_host_entry(host[:value])
+      end
+    end
+
+    def delete_host(ip)
+      entries = data.select(ip_matcher(ip))
+      if entries.empty?
+        log.info "no entry to delete for ip #{ip}"
+        return
+      end
+
+      if entries.size > 1
+        log.info "delete host with ip '#{ip}' removes more then one entry"
+      end
+
+      entries.each do |e|
+        log.info "deleting record #{e.inspect}"
+        data.delete(e[:key])
+      end
+    end
+
+    # replaces or adds new host entry. If more then one entry with given ip exists
+    # then replaces the last instance
+    def set_host(ip, canonical, aliases = [])
+      entries = data.select(ip_matcher(ip))
+      if entries.empty?
+        log.info "adding new entry for ip #{ip}"
+        entry_line = AugeasTree.new
+        entry_line["ipaddr"] = ip
+        entry_line["canonical"] = canonical
+        aliases_col = entry_line.collection("alias")
+        aliases.each do |a|
+          aliases_col.add(a)
+        end
+        data.add(unique_id, entry_line)
+        return
+      end
+
+      if entries.size > 1
+        log.info "more then one entry with ip '#{ip}'. Replacing last one."
+      end
+
+      entry = entries.last[:value]
+      entry["ipaddr"] = ip
+      entry["canonical"] = canonical
+      # clear previous aliases
+      entry.delete("alias")
+      entry.delete("alias[]")
+      aliases_col = entry.collection("alias")
+      aliases.each do |a|
+        aliases_col.add(a)
+      end
+    end
+
+    # adds new entry, even if it exists
+    def add_host(ip, canonical, aliases = [])
+      log.info "adding new entry for ip #{ip}"
+      entry_line = AugeasTree.new
+      entry_line["ipaddr"] = ip
+      entry_line["canonical"] = canonical
+      aliases_col = entry_line.collection("alias")
+      aliases.each do |a|
+        aliases_col.add(a)
+      end
+      data.add(unique_id, entry_line)
+    end
+
+    def remove_hostname(hostname)
+      entries = data.select(hostname_matcher(hostname))
+      entries.each do |entry|
+        entry = entry[:value]
+        if entry["canonical"] == hostname
+          aliases = aliases_for(entry)
+          if aliases.empty?
+            delete_host(entry["ipaddr"])
+          else
+            set_host(entry["ipaddr"], aliases.first, aliases[1..-1])
+          end
+        else
+          reduced_aliases = aliases_for(entry)
+          reduced_aliases.delete(hostname)
+          set_host(entry["ipaddr"], entry["canonical"], reduced_aliases)
+        end
+      end
+    end
+
+  private
+
+    def ip_matcher(ip)
+      Matcher.new { |k, v| v["ipaddr"] == ip }
+    end
+
+    def hostname_matcher(hostname)
+      Matcher.new do |k, v|
+        v["canonical"] == hostname || aliases_for(v).include?(hostname)
+      end
+    end
+
+    def aliases_for(entry)
+      entry["alias[]"] ? entry.collection("alias").map{ |a| a } : [entry["alias"]].compact
+    end
+
+    def single_host_entry(entry)
+      result = [entry["canonical"]]
+      result.concat(aliases_for(entry))
+      result.join(" ")
+    end
+
+    def unique_id
+      id = 1
+      loop do
+        return id.to_s unless data[id.to_s]
+        id += 1
+      end
+    end
+  end
+end