From 8858f65fe89da1008b90396c1fc3db943248e52e Mon Sep 17 00:00:00 2001
From: Jeff Kunkle <jeff.kunkle@nearinfinity.com>
Date: Fri, 12 Aug 2011 21:09:18 -0400
Subject: [PATCH] Add async store implementation

---
 lib/system_metrics.rb                   |  1 +
 lib/system_metrics/async_store.rb       | 57 +++++++++++++++++++++++++
 lib/system_metrics/config.rb            |  2 +-
 spec/system_metrics/async_store_spec.rb | 50 ++++++++++++++++++++++
 spec/system_metrics/store_spec.rb       |  2 +-
 5 files changed, 110 insertions(+), 2 deletions(-)
 create mode 100644 lib/system_metrics/async_store.rb
 create mode 100644 spec/system_metrics/async_store_spec.rb

diff --git a/lib/system_metrics.rb b/lib/system_metrics.rb
index 637e943..494e525 100644
--- a/lib/system_metrics.rb
+++ b/lib/system_metrics.rb
@@ -4,6 +4,7 @@ module SystemMetrics
   autoload :Middleware,     'system_metrics/middleware'
   autoload :NestedEvent,    'system_metrics/nested_event'
   autoload :Store,          'system_metrics/store'
+  autoload :AsyncStore,     'system_metrics/async_store'
   autoload :Version,        'system_metrics/version'
 
   def self.collection_on
diff --git a/lib/system_metrics/async_store.rb b/lib/system_metrics/async_store.rb
new file mode 100644
index 0000000..73f1305
--- /dev/null
+++ b/lib/system_metrics/async_store.rb
@@ -0,0 +1,57 @@
+require 'thread'
+
+module SystemMetrics
+  class AsyncStore
+
+    # An instrumenter that does not send notifications. This is used in the
+    # AsyncStore so saving events does not send any notifications, not even
+    # for logging.
+    class VoidInstrumenter < ::ActiveSupport::Notifications::Instrumenter
+      def instrument(name, payload={})
+        yield(payload) if block_given?
+      end
+    end
+
+    def initialize
+      @queue = Queue.new
+      @thread = Thread.new do
+        set_void_instrumenter
+        consume
+      end
+    end
+
+    def save(events)
+      @queue << events
+    end
+
+    protected
+      def set_void_instrumenter
+        Thread.current[:"instrumentation_#{notifier.object_id}"] = VoidInstrumenter.new(notifier)
+      end
+
+      def notifier
+        ActiveSupport::Notifications.notifier
+      end
+
+      def consume
+        while events = @queue.pop
+          root_event = SystemMetrics::NestedEvent.arrange(events, :presort => false)
+          root_model = create_metric(root_event)
+          root_model.update_attributes(:request_id => root_model.id)
+          save_tree(root_event.children, root_model.id, root_model.id)
+        end
+      end
+
+      def save_tree(events, request_id, parent_id)
+        events.each do |event|
+          model = create_metric(event, :request_id => request_id, :parent_id => parent_id)
+          save_tree(event.children, request_id, model.id)
+        end
+      end
+
+      def create_metric(event, merge_params={})
+        SystemMetrics::Metric.create(event.to_hash.merge(merge_params))
+      end
+
+  end
+end
diff --git a/lib/system_metrics/config.rb b/lib/system_metrics/config.rb
index a08eae6..265ade4 100644
--- a/lib/system_metrics/config.rb
+++ b/lib/system_metrics/config.rb
@@ -3,7 +3,7 @@ class Config
     attr_accessor :store, :instruments, :notification_exclude_patterns, :path_exclude_patterns
 
     def initialize
-      self.store = SystemMetrics::Store.new
+      self.store = SystemMetrics::AsyncStore.new
       self.notification_exclude_patterns = []
       self.path_exclude_patterns = [/system\/metrics/, /system_metrics/]
       self.instruments = [
diff --git a/spec/system_metrics/async_store_spec.rb b/spec/system_metrics/async_store_spec.rb
new file mode 100644
index 0000000..445fe1f
--- /dev/null
+++ b/spec/system_metrics/async_store_spec.rb
@@ -0,0 +1,50 @@
+require File.dirname(__FILE__) + '/../spec_helper'
+require 'system_metrics/metric'
+
+describe SystemMetrics::AsyncStore do
+  include NotificationsSupport
+
+  describe '#save' do
+    it 'should save an array of events hierarchically' do
+      parent = event(:start => Time.now - 10.seconds, :end => Time.now)
+      child = event(:start => Time.now - 9.seconds, :end => Time.now - 1.seconds)
+      grandchild = event(:start => Time.now - 8.seconds, :end => Time.now - 2.seconds)
+
+      store = SystemMetrics::AsyncStore.new
+
+      lambda {
+        store.save([grandchild, child, parent])
+        sleep(0.1)
+      }.should change(SystemMetrics::Metric, :count).by(3)
+
+      metrics = SystemMetrics::Metric.all
+      verify_equal(parent, metrics[0])
+      verify_equal(child, metrics[0].children[0])
+      verify_equal(grandchild, metrics[0].children[0].children[0])
+    end
+
+    it 'should not attempt to save anything if passed an empty array of events' do
+      store = SystemMetrics::AsyncStore.new
+      lambda { store.save([]); sleep(0.1) }.should_not change(SystemMetrics::Metric, :count)
+    end
+
+    it 'should not attempt to save anything if passed a nil' do
+      store = SystemMetrics::AsyncStore.new
+      lambda { store.save(nil); sleep(0.1) }.should_not change(SystemMetrics::Metric, :count)
+    end
+  end
+
+  private
+
+    def verify_equal(event, metric)
+      event.name.should == metric.name
+      event.action.should == metric.action
+      event.category.should == metric.category
+      event.transaction_id.should == metric.transaction_id
+      event.payload.should == metric.payload
+      event.started_at.should be_within(1).of(metric.started_at)
+      event.duration.should be_within(1).of(metric.duration)
+      event.exclusive_duration.should be_within(1).of(metric.exclusive_duration)
+    end
+
+end
diff --git a/spec/system_metrics/store_spec.rb b/spec/system_metrics/store_spec.rb
index 2e99d86..ac9c33d 100644
--- a/spec/system_metrics/store_spec.rb
+++ b/spec/system_metrics/store_spec.rb
@@ -11,7 +11,7 @@
       grandchild = event(:start => Time.now - 8.seconds, :end => Time.now - 2.seconds)
 
       store = SystemMetrics::Store.new
-      
+
       lambda {
         store.save([grandchild, child, parent])
       }.should change(SystemMetrics::Metric, :count).by(3)