From 2d08baf60cbd36d4bd0a112b574a8b755eeaa638 Mon Sep 17 00:00:00 2001
From: Stepan Palamarchuk <stepan@fb.com>
Date: Mon, 31 Mar 2014 14:19:54 -0700
Subject: [PATCH] Add loopOnce() method to folly::EventBase

Summary: Add loopOnce() method which provides functionality similar to event_base_loop(base, EVLOOP_ONCE);

Test Plan: fbmake

Reviewed By: simpkins@fb.com

FB internal diff: D1249753
---
 folly/io/async/EventBase.cpp | 12 ++++++++++++
 folly/io/async/EventBase.h   | 11 +++++++++++
 2 files changed, 23 insertions(+)

diff --git a/folly/io/async/EventBase.cpp b/folly/io/async/EventBase.cpp
index 68a42f58..6e860406 100644
--- a/folly/io/async/EventBase.cpp
+++ b/folly/io/async/EventBase.cpp
@@ -223,6 +223,14 @@ void EventBase::waitUntilRunning() {
 
 // enters the event_base loop -- will only exit when forced to
 bool EventBase::loop() {
+  return loopBody();
+}
+
+bool EventBase::loopOnce() {
+  return loopBody(true);
+}
+
+bool EventBase::loopBody(bool once) {
   VLOG(5) << "EventBase(): Starting loop.";
   int res = 0;
   bool ranLoopCallbacks;
@@ -302,6 +310,10 @@ bool EventBase::loop() {
 
     VLOG(5) << "EventBase " << this << " loop time: " <<
       getTimeDelta(&prev).count();
+
+    if (once) {
+      break;
+    }
   }
   // Reset stop_ so loop() can be called again
   stop_ = false;
diff --git a/folly/io/async/EventBase.h b/folly/io/async/EventBase.h
index fa9a3fe5..46c84b8d 100644
--- a/folly/io/async/EventBase.h
+++ b/folly/io/async/EventBase.h
@@ -143,6 +143,15 @@ class EventBase : private boost::noncopyable, public TimeoutManager {
    */
   bool loop();
 
+  /**
+   * Wait for some events to become active, run them, then return.
+   *
+   * This is useful for callers that want to run the loop manually.
+   *
+   * Returns the same result as loop().
+   */
+  bool loopOnce();
+
   /**
    * Runs the event loop.
    *
@@ -479,6 +488,8 @@ class EventBase : private boost::noncopyable, public TimeoutManager {
   typedef LoopCallback::List LoopCallbackList;
   class FunctionRunner;
 
+  bool loopBody(bool once = false);
+
   // executes any callbacks queued by runInLoop(); returns false if none found
   bool runLoopCallbacks(bool setContext = true);
 
-- 
2.34.1