Use Metrics libraries for HTTP serving and JSON serialization

Gemfile

@@ -1,6 +1,7 @@
 source 'https://rubygems.org/'
 
-gemspec
+gemspec name: 'multimeter'
+gemspec name: 'multimeter-http'
 
 group :examples do
   gem 'rack'

ext/java/multimeter/Counter.java

@@ -12,6 +12,7 @@
 import org.jruby.runtime.ObjectAllocator;
 import org.jruby.runtime.ThreadContext;
 import org.jruby.runtime.builtin.IRubyObject;
+import org.jruby.javasupport.JavaUtil;
 
 import static org.jruby.runtime.Visibility.PRIVATE;
 
@@ -30,6 +31,11 @@ public Counter(Ruby runtime, com.codahale.metrics.Counter counter) {
     this.counter = counter;
   }
 
+  @JRubyMethod(name="to_java")
+  public IRubyObject toJava(ThreadContext ctx) {
+    return JavaUtil.convertJavaToUsableRubyObject(ctx.runtime, counter);
+  }
+
   @JRubyMethod
   public IRubyObject count(ThreadContext ctx) {
     return ctx.runtime.newFixnum(counter.getCount());

ext/java/multimeter/Gauge.java

@@ -31,6 +31,11 @@ public Gauge(Ruby runtime, com.codahale.metrics.Gauge<? extends Object> gauge) {
     this.gauge = gauge;
   }
 
+  @JRubyMethod(name="to_java")
+  public IRubyObject toJava(ThreadContext ctx) {
+    return JavaUtil.convertJavaToUsableRubyObject(ctx.runtime, gauge);
+  }
+
   @JRubyMethod
   public IRubyObject value(ThreadContext ctx) {
     Object value = gauge.getValue();

ext/java/multimeter/Histogram.java

@@ -12,6 +12,7 @@
 import org.jruby.runtime.ObjectAllocator;
 import org.jruby.runtime.ThreadContext;
 import org.jruby.runtime.builtin.IRubyObject;
+import org.jruby.javasupport.JavaUtil;
 
 import static org.jruby.runtime.Visibility.PRIVATE;
 
@@ -30,6 +31,11 @@ public Histogram(Ruby runtime, com.codahale.metrics.Histogram histogram) {
     this.histogram = histogram;
   }
 
+  @JRubyMethod(name="to_java")
+  public IRubyObject toJava(ThreadContext ctx) {
+    return JavaUtil.convertJavaToUsableRubyObject(ctx.runtime, histogram);
+  }
+
   @JRubyMethod
   public IRubyObject count(ThreadContext ctx) {
     return ctx.runtime.newFixnum(histogram.getCount());

ext/java/multimeter/Meter.java

@@ -12,6 +12,7 @@
 import org.jruby.runtime.ObjectAllocator;
 import org.jruby.runtime.ThreadContext;
 import org.jruby.runtime.builtin.IRubyObject;
+import org.jruby.javasupport.JavaUtil;
 
 import static org.jruby.runtime.Visibility.PRIVATE;
 
@@ -30,6 +31,11 @@ public Meter(Ruby runtime, com.codahale.metrics.Meter meter) {
     this.meter = meter;
   }
 
+  @JRubyMethod(name="to_java")
+  public IRubyObject toJava(ThreadContext ctx) {
+    return JavaUtil.convertJavaToUsableRubyObject(ctx.runtime, meter);
+  }
+
   @JRubyMethod
   public IRubyObject count(ThreadContext ctx) {
     return ctx.runtime.newFixnum(meter.getCount());

ext/java/multimeter/Timer.java

@@ -12,6 +12,7 @@
 import org.jruby.runtime.ObjectAllocator;
 import org.jruby.runtime.ThreadContext;
 import org.jruby.runtime.builtin.IRubyObject;
+import org.jruby.javasupport.JavaUtil;
 
 import static org.jruby.runtime.Visibility.PRIVATE;
 
@@ -35,6 +36,11 @@ public Timer(Ruby runtime, com.codahale.metrics.Timer timer) {
     this.timer = timer;
   }
 
+  @JRubyMethod(name="to_java")
+  public IRubyObject toJava(ThreadContext ctx) {
+    return JavaUtil.convertJavaToUsableRubyObject(ctx.runtime, timer);
+  }
+
   @JRubyMethod
   public IRubyObject count(ThreadContext ctx) {
     return ctx.runtime.newFixnum(timer.getCount());

lib/multimeter.rb

@@ -3,91 +3,55 @@
 require 'metrics-core-jars'
 require 'multimeter_metrics'
 require 'json'
+require 'multimeter/rack'
+require 'multimeter/json'
 
 module Metrics
   include_package 'com.codahale.metrics'
 end
 
 module Multimeter
+  extend Rack
+
   class MetricRegistry
-    def to_h
-      h = {}
-      metrics.each do |metric_name, metric|
-        h[metric_name] = metric.to_h
-      end
-      h
+    def to_json
+      Json.dump(self)
     end
   end
 
   class Meter
-    def to_h
-      {
-        :type => :meter,
-        :count => count,
-        :mean_rate => mean_rate,
-        :one_minute_rate => one_minute_rate,
-        :five_minute_rate => five_minute_rate,
-        :fifteen_minute_rate => fifteen_minute_rate
-      }
+    def to_json
+      Json.dump(self)
     end
   end
 
   class Counter
-    def to_h
-      {
-        :type => :counter,
-        :count => count
-      }
+    def to_json
+      Json.dump(self)
     end
   end
 
   class Histogram
-    def to_h
-      {
-        :type => :histogram,
-        :count => count,
-      }.merge(snapshot.to_h(NANO_TO_MILLI_SCALE))
+    def to_json
+      Json.dump(self)
     end
   end
 
   class Timer
-    def to_h
-      {
-        :type => :timer,
-        :count => count,
-        :mean_rate => mean_rate,
-        :one_minute_rate => one_minute_rate,
-        :five_minute_rate => five_minute_rate,
-        :fifteen_minute_rate => fifteen_minute_rate,
-      }.merge(snapshot.to_h(NANO_TO_MILLI_SCALE))
+    def to_json
+      Json.dump(self)
     end
   end
 
   class Snapshot
-    def to_h(scale=1)
-      {
-        :max => max * scale,
-        :min => min * scale,
-        :mean => mean * scale,
-        :std_dev => std_dev * scale,
-        :median => median * scale,
-        :percentiles => {
-          '75' => p75 * scale,
-          '95' => p95 * scale,
-          '98' => p98 * scale,
-          '99' => p99 * scale,
-          '99.9' => p999 * scale,
-        }
-      }
+    def to_json
+      Json.dump(self)
     end
   end
 
   class Gauge
-    def to_h
-      {
-        :type => :gauge,
-        :value => value,
-      }
+    def to_json
+      Json.dump(self)
     end
   end
 
@@ -98,51 +62,4 @@ def self.create_registry
   def self.jmx(registry, options = {})
     Metrics::JmxReporter.forRegistry(registry.to_java).inDomain(options[:domain] || 'multimeter').build.tap(&:start)
   end
-
-  def self.http(registry, rack_handler, options={})
-    server_thread = Java::JavaLang::Thread.new do
-      rack_handler.run(Http.create_app(registry), options)
-    end
-    server_thread.daemon = true
-    server_thread.name = 'multimeter-http-server'
-    server_thread.start
-    server_thread
-  end
-
-  private
-
-  NANO_TO_MILLI_SCALE = 1.0/1_000_000
-
-  module Http
-    class BadRequest < StandardError; end
-
-    COMMON_HEADERS = {'Connection' => 'close'}.freeze
-    JSON_HEADERS = COMMON_HEADERS.merge('Content-Type' => 'application/json').freeze
-    JSONP_HEADERS = COMMON_HEADERS.merge('Content-Type' => 'application/javascript').freeze
-    ERROR_HEADERS = COMMON_HEADERS.merge('Content-Type' => 'text/plain').freeze
-
-    def self.create_app(registry)
-      proc do |env|
-        begin
-          body = registry.to_h.to_json
-          headers = JSON_HEADERS
-          if (callback_name = env['QUERY_STRING'][/callback=([^$&]+)/, 1])
-            if callback_name =~ /^[\w\d.]+$/
-              body = "#{callback_name}(#{body});"
-              headers = JSONP_HEADERS
-            else
-              raise BadRequest
-            end
-          else
-            headers = headers.merge('Access-Control-Allow-Origin' => '*')
-          end
-          [200, headers, [body]]
-        rescue BadRequest => e
-          [400, ERROR_HEADERS, ['Bad Request']]
-        rescue => e
-          [500, ERROR_HEADERS, ["Internal Server Error\n\n", e.message, "\n\t", *e.backtrace.join("\n\t")]]
-        end
-      end
-    end
-  end
 end

lib/multimeter/http.rb

@@ -0,0 +1,58 @@
+# encoding: utf-8
+
+require 'multimeter'
+require 'metrics-servlets-jars'
+require 'rjack-jetty'
+
+module Metrics
+  module Servlets
+    include_package 'com.codahale.metrics.servlets'
+  end
+end
+
+module Jetty
+  include_package 'org.eclipse.jetty.server'
+  include_package 'org.eclipse.jetty.servlet'
+end
+
+module Multimeter
+  module Http
+    def http(registry, options={})
+      server = Jetty::Server.new(options[:port] || 5747)
+      server.handler = create_servlet_context(registry)
+      Server.new(server)
+    end
+
+    private
+
+    def create_servlet_context(registry)
+      context = Jetty::ServletContextHandler.new(Jetty::ServletContextHandler::SESSIONS)
+      context.context_path = '/'
+      context.set_attribute(Metrics::Servlets::MetricsServlet::METRICS_REGISTRY, registry.to_java);
+      context.add_servlet(Metrics::Servlets::MetricsServlet.java_class, '/*')
+      context
+    end
+
+    class Server
+      def initialize(server)
+        @server = server
+      end
+
+      def start
+        @server.start
+        self
+      end
+
+      def stop
+        @server.stop
+        self
+      end
+
+      def join
+        @server.join
+      end
+    end
+  end
+
+  extend Http
+end

lib/multimeter/json.rb

@@ -0,0 +1,39 @@
+# encoding: utf-8
+
+require 'metrics-json-jars'
+
+module Metrics
+  module Json
+    include_package 'com.codahale.metrics.json'
+  end
+end
+
+module Jackson
+  module Databind
+    include_package 'com.fasterxml.jackson.databind'
+  end
+end
+
+module Multimeter
+  class Json
+    def initialize
+      @object_mapper = Jackson::Databind::ObjectMapper.new
+    end
+
+    def setup
+      metrics_module = Metrics::Json::MetricsModule.new(rate_unit = Java::JavaUtilConcurrent::TimeUnit::SECONDS, duration_unit = Java::JavaUtilConcurrent::TimeUnit::MILLISECONDS, show_samples = false)
+      @object_mapper.register_module(metrics_module)
+      self
+    end
+
+    def dump(metric)
+      stream = Java::JavaIo::ByteArrayOutputStream.new
+      @object_mapper.write_value(stream, metric.to_java)
+      String.from_java_bytes(stream.to_byte_array)
+    end
+
+    def self.dump(metric)
+      new.setup.dump(metric)
+    end
+  end
+end