change: move caching logic to separate class

lib/valid_email2/address.rb

@@ -3,6 +3,7 @@
 require "valid_email2"
 require "resolv"
 require "mail"
+require "valid_email2/dns_records_cache"
 
 module ValidEmail2
   class Address
@@ -11,7 +12,6 @@ class Address
     PROHIBITED_DOMAIN_CHARACTERS_REGEX = /[+!_\/\s'`]/
     DEFAULT_RECIPIENT_DELIMITER = '+'
     DOT_DELIMITER = '.'
-    MAX_CACHE_SIZE = 1_000
 
     # Cache structure: { domain (String): { records: [], cached_at: Time, ttl: Integer } }
     @@mx_servers_cache = {}
@@ -142,72 +142,30 @@ def address_contain_emoticons?(email)
     end
 
     def mx_servers
-      if @@mx_servers_cache.size > MAX_CACHE_SIZE
-        prune_cache(@@mx_servers_cache)
-      end
-
-      domain = address.domain.downcase
+      @mx_servers_cache ||= ValidEmail2::DnsRecordsCache.new
 
-      if @@mx_servers_cache[domain]
-        cache_entry = @@mx_servers_cache[domain]
-        if (Time.now - cache_entry[:cached_at]) < cache_entry[:ttl]
-          return cache_entry[:records]
-        else
-          @@mx_servers_cache.delete(domain)
+      @mx_servers_cache.fetch(address.domain.downcase) do
+        Resolv::DNS.open(@resolv_config) do |dns|
+          dns.timeouts = @dns_timeout
+          dns.getresources(address.domain, Resolv::DNS::Resource::IN::MX)
         end
       end
-
-      records = Resolv::DNS.open(@resolv_config) do |dns|
-        dns.timeouts = @dns_timeout
-        dns.getresources(address.domain, Resolv::DNS::Resource::IN::MX)
-      end
-
-      if records.any?
-        ttl = records.map(&:ttl).min
-        @@mx_servers_cache[domain] = { records: records, cached_at: Time.now, ttl: ttl }
-      end
-
-      records
     end
 
     def null_mx?
       mx_servers.length == 1 && mx_servers.first.preference == 0 && mx_servers.first.exchange.length == 0
     end
 
     def mx_or_a_servers
-      if @@mx_or_a_servers_cache.size > MAX_CACHE_SIZE
-        prune_cache(@@mx_or_a_servers_cache)
-      end
+      @mx_or_a_servers_cache ||= ValidEmail2::DnsRecordsCache.new
 
-      domain = address.domain.downcase
-
-      if @@mx_or_a_servers_cache[domain]
-        cache_entry = @@mx_or_a_servers_cache[domain]
-        if (Time.now - cache_entry[:cached_at]) < cache_entry[:ttl]
-          return cache_entry[:records]
-        else
-          @@mx_or_a_servers_cache.delete(domain)
+      @mx_or_a_servers_cache.fetch(address.domain.downcase) do
+        Resolv::DNS.open(@resolv_config) do |dns|
+          dns.timeouts = @dns_timeout
+          (mx_servers.any? && mx_servers) ||
+            dns.getresources(address.domain, Resolv::DNS::Resource::IN::A)
         end
       end
-
-      records = Resolv::DNS.open(@resolv_config) do |dns|
-        dns.timeouts = @dns_timeout
-        (mx_servers.any? && mx_servers) ||
-          dns.getresources(address.domain, Resolv::DNS::Resource::IN::A)
-      end
-
-      if records.any?
-        ttl = records.map(&:ttl).min
-        @@mx_or_a_servers_cache[domain] = { records: records, cached_at: Time.now, ttl: ttl }
-      end
-
-      records
-    end
-
-    def prune_cache(cache)
-      entries_sorted_by_cached_at_asc = (cache.sort_by { |_domain, data| data[:cached_at] }).flatten
-      entries_to_remove = entries_sorted_by_cached_at_asc.first(cache.size - MAX_CACHE_SIZE)
-      entries_to_remove.each { |domain| cache.delete(domain) }
     end
   end
 end

lib/valid_email2/dns_records_cache.rb

@@ -0,0 +1,37 @@
+module ValidEmail2
+  class DnsRecordsCache
+    MAX_CACHE_SIZE = 1_000
+
+    def initialize
+      # Cache structure: { domain (String): { records: [], cached_at: Time, ttl: Integer } }
+      @cache = {}
+    end
+
+    def fetch(domain, &block)
+      prune(@cache) if @cache.size > MAX_CACHE_SIZE
+
+      cache_entry = @cache[domain]
+
+      if cache_entry && (Time.now - cache_entry[:cached_at]) < cache_entry[:ttl]
+        return cache_entry[:records]
+      else
+        @cache.delete(domain)
+      end
+
+      records = block.call
+
+      if records.any?
+        ttl = records.map(&:ttl).min
+        @cache[domain] = { records: records, cached_at: Time.now, ttl: ttl }
+      end
+
+      records
+    end
+
+    def prune(cache)
+      entries_sorted_by_cached_at_asc = (cache.sort_by { |_domain, data| data[:cached_at] }).flatten
+      entries_to_remove = entries_sorted_by_cached_at_asc.first(cache.size - MAX_CACHE_SIZE)
+      entries_to_remove.each { |domain| cache.delete(domain) }
+    end
+  end
+end