Make the HTTP client threadsafe

Author: monorkin

Gemfile.lock

@@ -2,6 +2,8 @@ PATH
   remote: .
   specs:
     croatia (0.4.0)
+      concurrent-ruby
+      connection_pool
       nokogiri
       openssl
       rexml

README.md

@@ -65,7 +65,8 @@ Croatia.configure do |config|
   # Fiscalization defaults
   config.fiscalization = {
     credential: "path/to/your/credential.p12", # or File.read("path/to/your/credential.p12")
-    password: ENV["FISCALIZATION_CREDENTIAL_PASSWORD"]
+    password: ENV["FISCALIZATION_CREDENTIAL_PASSWORD"],
+  }
   }
   # You can also use separate private key and certificate files instead of a full credential (.p12)
   # config.fiscalization = {
@@ -76,6 +77,13 @@ Croatia.configure do |config|
   #   },
   #   password: "credential_password" # only needed for encrypted private keys
   # }
+  #
+  # Additional fiscalization options
+  # config.fiscalization = {
+  #   pool_size: 5, # Number of threads to use for fiscalization requests; with Rails you'd want to set this to ENV.fetch("RAILS_MAX_THREADS", 5).to_i
+  #   pool_timeout: 5, # Timeout for each fiscalization request in seconds
+  #   keep_alive_timeout: 60, # For how long to keep a connection open before closing it - speeds up consecutive requests
+  # }
 end
 ```
 

croatia.gemspec

@@ -36,10 +36,12 @@ Gem::Specification.new do |spec|
   spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
   spec.require_paths = [ "lib" ]
 
+  spec.add_dependency "concurrent-ruby"
+  spec.add_dependency "connection_pool"
+  spec.add_dependency "nokogiri"
   spec.add_dependency "openssl"
   spec.add_dependency "rexml"
   spec.add_dependency "tzinfo"
-  spec.add_dependency "nokogiri"
 
   # For more information and examples about making a new gem, check out our
   # guide at: https://bundler.io/guides/creating_gem.html

lib/croatia/config.rb

@@ -13,7 +13,11 @@ class Croatia::Config
     consumption_tax: Hash.new(0.0),
     other: Hash.new(0.0)
   }
-  DEFAULT_FISCALIZATION = {}
+  DEFAULT_FISCALIZATION = {
+    pool_size: Croatia::Fiscalizer::DEFAULT_POOL_SIZE,
+    pool_timeout: Croatia::Fiscalizer::DEFAULT_POOL_TIMEOUT,
+    keep_alive_timeout: Croatia::Fiscalizer::DEFAULT_KEEP_ALIVE_TIMEOUT
+  }
 
   attr_accessor :tax_rates, :fiscalization
 

lib/croatia/fiscalizer.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "concurrent"
+require "connection_pool"
 require "digest/md5"
 require "net/http"
 require "openssl"
@@ -13,57 +15,65 @@ class Croatia::Fiscalizer
   TZ = TZInfo::Timezone.get("Europe/Zagreb")
   QR_CODE_BASE_URL = "https://porezna.gov.hr/rn"
   DEFAULT_PORT = 443
-  DEFAULT_TIMEOUT = 30
+  DEFAULT_KEEP_ALIVE_TIMEOUT = 60
+  DEFAULT_POOL_SIZE = 5
+  DEFAULT_POOL_TIMEOUT = 5
   USER_AGENT = "Croatia/#{Croatia::VERSION} Ruby/#{RUBY_VERSION} (Fiscalization Client; +https://github.com/monorkin/croatia)"
 
   class << self
-    attr_accessor :http_clients
+    def http_pools
+      @http_pools ||= Concurrent::Map.new
+    end
 
     def with_http_client_for(**options, &block)
-      client = http_client_for(**options)
-      retrying = false
+      pool = http_pool_for(**options)
+
+      pool.with do |client|
+        retrying = false
 
-      begin
-        block.call(client)
-      rescue IOError, EOFError, Errno::ECONNRESET
-        raise if retrying
+        begin
+          block.call(client)
+        rescue IOError, EOFError, Errno::ECONNRESET
+          raise if retrying
 
-        retrying = true
-        client.finish rescue nil
-        client.start
+          retrying = true
+          client.finish rescue nil
+          client.start
 
-        retry
+          retry
+        end
       end
     end
 
-    def http_client_for(host:, credential:, port: DEFAULT_PORT, timeout: DEFAULT_TIMEOUT)
-      self.http_clients ||= {}
+    def http_pool_for(host:, credential:, port: DEFAULT_PORT, keep_alive_timeout: nil, size: nil, timeout: nil)
+      size ||= Croatia.config.fiscalization.fetch(:pool_size, DEFAULT_POOL_SIZE)
+      timeout ||= Croatia.config.fiscalization.fetch(:pool_timeout, DEFAULT_POOL_TIMEOUT)
+      keep_alive_timeout ||= Croatia.config.fiscalization.fetch(:keep_alive_timeout, DEFAULT_KEEP_ALIVE_TIMEOUT)
 
       # MD5 is fast, but not cryptographically secure.
       # So the fingerprint is computed on less sensitive information.
       fingerprint = Digest::MD5.hexdigest("#{credential.certificate.serial}:#{credential.certificate.subject}")
       key = "#{host}:#{port}/#{fingerprint}?timeout=#{timeout}"
 
-      client = http_clients[key]
-
-      if client&.active?
-        return client
-      end
-
-      client&.finish rescue nil
-      http_clients[key] = Net::HTTP.new(host, port).tap do |client|
-        client.use_ssl = true
-        client.verify_mode = OpenSSL::SSL::VERIFY_PEER
-        client.cert = credential.certificate
-        client.key = credential.key
-        client.keep_alive_timeout = timeout
-        client.start
+      http_pools.compute_if_absent(key) do
+        ConnectionPool.new(size: pool_size, timeout: pool_timeout) do
+          Net::HTTP.new(host, port).tap do |client|
+            client.use_ssl = true
+            client.verify_mode = OpenSSL::SSL::VERIFY_PEER
+            client.cert = credential.certificate
+            client.key = credential.key
+            client.keep_alive_timeout = keep_alive_timeout if keep_alive_timeout
+            client.start
+          end
+        end
       end
     end
 
-    def shutdown_all_clients
-      http_clients&.each_value { |c| c.finish rescue nil }
-      self.http_clients = {}
+    def shutdown
+      http_pools.each_value do |pool|
+        pool.shutdown { |client| client.finish rescue nil }
+      end
+      http_pools.clear
     end
   end
 

lib/croatia/fiscalizer/xml_builder.rb

@@ -129,6 +129,15 @@ def sign(document:, credential:)
       document.root.add_element(signature, { "xmlns" => "http://www.w3.org/2000/09/xmldsig#" })
     end
 
+    def echo(message)
+      REXML::Document.new.tap do |doc|
+        doc.add_element("tns:EchoRequest", {
+          "xmlns:tns" => TNS,
+          "xmlns:xsi" => XSI,
+      }).text = message
+      end
+    end
+
     private
 
       def build(envelope:, invoice:, message_id:, timezone: Croatia::Fiscalizer::TZ, **options)

test/croatia/fiscalizer/xml_builder_test.rb

@@ -777,4 +777,25 @@ def test_sign_with_invoice_document
       end
     end
   end
+
+  def test_echo
+    message = "Hello, World!"
+    document = Croatia::Fiscalizer::XMLBuilder.echo(message)
+
+    expected_xml = <<~XML
+      <tns:EchoRequest xmlns:tns='http://www.apis-it.hr/fin/2012/types/f73' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'>Hello, World!</tns:EchoRequest>
+    XML
+
+    assert_xml_equal expected_xml, document
+  end
+
+  def test_echo_with_nil
+    document = Croatia::Fiscalizer::XMLBuilder.echo(nil)
+
+    expected_xml = <<~XML
+      <tns:EchoRequest xmlns:tns='http://www.apis-it.hr/fin/2012/types/f73' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'></tns:EchoRequest>
+    XML
+
+    assert_xml_equal expected_xml, document
+  end
 end