initial ignore logic flow

lib/scout_apm/sampling.rb

@@ -1,18 +1,41 @@
 module ScoutApm
   class Sampling
+    attr_reader :global_sample_rate, :sample_endpoints, :sample_uri_regex, :sample_jobs, :ignore_uri_regex, :ignore_jobs
 
     def initialize(config)
       @global_sample_rate = config.value('sample_rate')
-      @sampled_endpoints = individual_sample_to_hash(config.value('sampled_endpoints'))
-      @sampled_jobs = individual_sample_to_hash(config.value('sampled_jobs'))
-      @ignored_endpoints = config.value('ignored_endpoints').split(',')
-      @ignored_jobs = config.value('ignored_jobs').split(',')
+      # web endpoints matched prefix by regex
+      # jobs matched explicitly by name
+      @sample_endpoints = individual_sample_to_hash(config.value('sample_endpoints'))
+      @sample_uri_regex = create_uri_regex(sample_endpoints.keys)
+      @sample_jobs = individual_sample_to_hash(config.value('sample_jobs'))
+      @ignore_uri_regex = create_uri_regex(config.value('ignore_endpoints'))
+      @ignore_jobs = config.value('ignore_jobs').split(',')
       # TODO make this safer/smarter
     end
 
     def ignored?(transaction)
-      # a bunch of logic to determine if a transaction should be ignored
-      return
+      # global sample check
+      if global_sample_rate
+        return true if sample?(global_sample_rate)
+      end
+
+      # job or endpoint?
+      # check ignored _then_ sampled
+      if transaction.job?
+        job_name = transaction.layer_finder.job.name
+        return true if ignore_job?(transaction.job_name)
+        if sample_jobs.has_key?(transaction.job_name)
+          return true if sample?(sample_jobs[transaction.job_name])
+        end
+      elsif transaction.web?
+        return true if ignore_uri?(transaction.annotations[:uri])
+        if sample_uri?(transaction.annotations[:uri])
+          return true if sample?(sample_endpoints[transaction.annotations[:uri]])
+        end
+      end
+
+      false
     end
 
     private
@@ -27,5 +50,29 @@ def individual_sample_to_hash(sampling_config)
       end
       sample_hash
     end
+
+    def create_uri_regex(prefixes)
+      regexes = Array(prefixes).
+        reject{|prefix| prefix == ""}.
+        map {|prefix| %r{\A#{prefix}} }
+      Regexp.union(*regexes)
+    end
+
+    def ignore_uri?(uri)
+      !! ignore_uri_regex.match(uri)
+    end
+
+    def sample_uri?(uri)
+      !! sample_uri_regex.match(uri)
+    end
+
+    def ignore_job?(job_name)
+      @ignored_jobs.include?(job_name)
+    end
+
+    def sample?(rate)
+      rand * 100 > rate
+    end
+
   end
 end