Get harness-chain working

To use, do:

NO_VIEWER=1 HARNESS_CHAIN="vernier,ractor" ruby run_benchmarks.rb --harness=chain --skip-yjit psych-load

This runs vernier profiling for a ractor benchmark. You can also use
perf like this, but it's untested right now.

Author: luke-gruber

harness-chain/harness.rb

@@ -1,16 +1,37 @@
 require_relative '../harness/harness-common'
 
+# Ex: HARNESS_CHAIN="vernier,ractor"
+# Wraps the ractor harness in ther vernier harness
 CHAIN = ENV['HARNESS_CHAIN'].to_s.split(',')
 CHAIN.reject! { |el| el.to_s.strip.empty? }
 if CHAIN.size < 2
   $stderr.puts "You need to chain at least 2 harnesses. Exiting."
   exit 1
 end
 
+if CHAIN.include?("vernier") && CHAIN.last != "vernier"
+  require_relative "../harness/harness-extra"
+  def run_enough_to_profile(n, **kwargs, &block)
+    block.call
+  end
+end
+
+$current_harness = nil
+$benchmark_methods = []
+
+class Object
+  def self.method_added(name)
+    if name ==  :run_benchmark && $current_harness
+      $benchmark_methods << [$current_harness, Object.instance_method(name)]
+    end
+  end
+end
+
 def run_benchmark(n, **kwargs, &block)
   CHAIN.each do |h|
     begin
       path = "../harness-#{h}/harness"
+      $current_harness = h
       require_relative path
     rescue LoadError => e
       if e.path == path
@@ -20,4 +41,12 @@ def run_benchmark(n, **kwargs, &block)
       raise
     end
   end
+  procs = [block]
+  $benchmark_methods.reverse_each do |harness_name, harness_method|
+    prok = procs.pop
+    procs << proc { harness_method.bind(self).call(n, **kwargs, &prok) }
+  end
+  raise "Bad logic: #{procs.size}" unless procs.size == 1
+  result = procs.last.call
+  result || return_results([0], [1.0])
 end