Add a constructor to folly::Codel

Summary: Making a new ctor so that we can pass in the parameters

Reviewed By: yfeldblum

Differential Revision: D17173662

fbshipit-source-id: ab518892694e1bec1179177e7d9477e3a89ff38d

folly/executors/Codel.cpp

@@ -27,7 +27,13 @@ using namespace std::chrono;
 namespace folly {
 
 Codel::Codel()
-    : codelMinDelayNs_(0),
+    : Codel(Codel::Options()
+                .setInterval(milliseconds(FLAGS_codel_interval))
+                .setTargetDelay(milliseconds(FLAGS_codel_target_delay))) {}
+
+Codel::Codel(const Options& options)
+    : options_(options),
+      codelMinDelayNs_(0),
       codelIntervalTimeNs_(
           duration_cast<nanoseconds>(steady_clock::now().time_since_epoch())
               .count()),
@@ -91,11 +97,11 @@ nanoseconds Codel::getMinDelay() {
 }
 
 milliseconds Codel::getInterval() {
-  return milliseconds(FLAGS_codel_interval);
+  return options_.interval();
 }
 
 milliseconds Codel::getTargetDelay() {
-  return milliseconds(FLAGS_codel_target_delay);
+  return options_.targetDelay();
 }
 
 milliseconds Codel::getSloughTimeout() {

folly/executors/Codel.h

@@ -56,8 +56,36 @@ namespace folly {
 /// 2. https://en.wikipedia.org/wiki/CoDel
 class Codel {
  public:
+  class Options {
+   public:
+    std::chrono::milliseconds interval() const {
+      return interval_;
+    }
+
+    Options& setInterval(std::chrono::milliseconds value) {
+      interval_ = value;
+      return *this;
+    }
+
+    std::chrono::milliseconds targetDelay() const {
+      return targetDelay_;
+    }
+
+    Options& setTargetDelay(std::chrono::milliseconds value) {
+      targetDelay_ = value;
+      return *this;
+    }
+
+   private:
+    std::chrono::milliseconds interval_;
+    std::chrono::milliseconds targetDelay_;
+  };
+
   Codel();
 
+  /// Preferable construction method
+  explicit Codel(const Options& options);
+
   /// Returns true if this request should be expired to reduce overload.
   /// In detail, this returns true if min_delay > target_delay for the
   /// interval, and this delay > 2 * target_delay.
@@ -80,6 +108,7 @@ class Codel {
   std::chrono::milliseconds getSloughTimeout();
 
  private:
+  Options options_;
   std::atomic<uint64_t> codelMinDelayNs_;
   std::atomic<uint64_t> codelIntervalTimeNs_;