output: make it go zoom (#19)

* output: make it go zoom

By declaring `concurrency :shared`, a single shared instance can be used by
pipeline workers _concurrently_ instead of the legacy sharing we get by default
that shares the instance _sequentially_.

* Update CHANGELOG.md

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 1.0.1
+  - Fix: improves throughput by allowing pipeline workers to share a plugin instance _concurrently_ instead of _sequentially_ [#19](https://github.com/logstash-plugins/logstash-integration-logstash/pull/19)
+
 ## 1.0.0
   - Introduces the load balancing mechanism to distribute the requests among the `hosts` [#16](https://github.com/logstash-plugins/logstash-integration-logstash/pull/16)
 

VERSION

@@ -1 +1 @@
-1.0.0
+1.0.1

lib/logstash/outputs/logstash.rb

@@ -12,6 +12,9 @@
 require "stud/interval" # Stud::stoppable_sleep
 
 class LogStash::Outputs::Logstash < LogStash::Outputs::Base
+
+  concurrency :shared
+
   extend LogStash::PluginMixins::ValidatorSupport::RequiredHostOptionalPortValidationAdapter
 
   include LogStash::PluginMixins::HttpClient[:with_deprecated => false]

spec/unit/logstash_output_spec.rb

@@ -21,6 +21,7 @@
     it { is_expected.to be_a_kind_of Class }
     it { is_expected.to be <= LogStash::Outputs::Base }
     it { is_expected.to have_attributes(:config_name => "logstash") }
+    it { is_expected.to have_attributes(:concurrency => :shared) }
   end
 
   describe "a plugin instance with minimal config" do