Retry wrapper

lib/gh.rb

@@ -14,6 +14,7 @@ module GH
   autoload :Normalizer,       'gh/normalizer'
   autoload :Pagination,       'gh/pagination'
   autoload :Parallel,         'gh/parallel'
+  autoload :Retry,            'gh/retry'
   autoload :Remote,           'gh/remote'
   autoload :Response,         'gh/response'
   autoload :ResponseXHeaderFormatter, 'gh/response_x_header_formatter'

lib/gh/retry.rb

@@ -0,0 +1,41 @@
+require 'gh'
+
+module GH
+  # Public: In some cases, the GitHub API can take some number of
+  # seconds to reflect a change in the system. This class catches 404
+  # responses for any GET request and retries the request.
+  class Retry < Wrapper
+    DEFAULTS = {
+      retries: 5,
+      wait: 1
+    }
+
+    attr_accessor :retries, :wait
+
+    def initialize(backend = nil, options = {})
+      options = DEFAULTS.merge options
+      super backend, options
+    end
+
+    def fetch_resource(key)
+      begin
+        decrement_retries!
+        super key
+      rescue GH::Error(response_status: 404) => e
+        retries_remaining? or raise e
+        sleep wait
+        fetch_resource key
+      end
+    end
+
+    private
+
+    def decrement_retries!
+      self.retries = self.retries - 1
+    end
+
+    def retries_remaining?
+      retries > 0
+    end
+  end
+end

spec/retry_spec.rb

@@ -0,0 +1,28 @@
+require 'spec_helper'
+
+describe GH::Retry do
+  let(:not_finder) do
+    Class.new(GH::MockBackend) do
+      def fetch_resource(key)
+        if key =~ %r{users/not-found}
+          @requests << key
+          error = Struct.new(:info).new(response_status: 404)
+          raise GH::Error.new(error)
+        end
+        super(key)
+      end
+    end
+  end
+
+  subject { described_class.new(not_finder.new, retries: 3, wait: 0.1) }
+
+  it 'retries request specified number of times' do
+    expect { subject['users/not-found'] }.to raise_error(GH::Error)
+    expect(subject.backend.requests.count).to eq 3
+  end
+
+  it 'does not retry when response is successful' do
+    subject['users/rkh']
+    expect(subject.backend.requests.count).to eq 1
+  end
+end

spec/spec_helper.rb

@@ -48,7 +48,7 @@ def fetch_resource(key)
       key_fn = sanitize_filename(key)
       file = File.expand_path("../payloads/#{key_fn}.yml", __FILE__)
       @requests << key
-       result = @data[key] ||= begin
+      result = @data[key] ||= begin
         unless File.exist? file
           res = allow_http { super }
           FileUtils.mkdir_p File.dirname(file)