Implement loopIgnoreKeepAlive()

Summary:
This is useful to fix legacy tests that use loop(), as keep-alive tokens are used more widely.

(Note: this ignores all push blocking failures!)

Reviewed By: yfeldblum

Differential Revision: D8065959

fbshipit-source-id: 2e7a27f538ac9d36eeea7ba3a882633a193141d1

folly/io/async/EventBase.cpp

@@ -252,11 +252,22 @@ bool EventBase::loop() {
   return loopBody();
 }
 
+bool EventBase::loopIgnoreKeepAlive() {
+  if (loopKeepAliveActive_) {
+    // Make sure NotificationQueue is not counted as one of the readers
+    // (otherwise loopBody won't return until terminateLoopSoon is called).
+    fnRunner_->stopConsuming();
+    fnRunner_->startConsumingInternal(this, queue_.get());
+    loopKeepAliveActive_ = false;
+  }
+  return loopBody(0, true);
+}
+
 bool EventBase::loopOnce(int flags) {
   return loopBody(flags | EVLOOP_ONCE);
 }
 
-bool EventBase::loopBody(int flags) {
+bool EventBase::loopBody(int flags, bool ignoreKeepAlive) {
   VLOG(5) << "EventBase(): Starting loop.";
 
   DCHECK(!invokingLoop_)
@@ -294,7 +305,9 @@ bool EventBase::loopBody(int flags) {
   }
 
   while (!stop_.load(std::memory_order_relaxed)) {
-    applyLoopKeepAlive();
+    if (!ignoreKeepAlive) {
+      applyLoopKeepAlive();
+    }
     ++nextLoopCnt_;
 
     // Run the before loop callbacks

folly/io/async/EventBase.h

@@ -254,6 +254,12 @@ class EventBase : private boost::noncopyable,
    */
   bool loop();
 
+  /**
+   * Same as loop(), but doesn't wait for all keep-alive tokens to be released.
+   */
+  [[deprecated("This should only be used in legacy unit tests")]]
+  bool loopIgnoreKeepAlive();
+
   /**
    * Wait for some events to become active, run them, then return.
    *
@@ -691,7 +697,7 @@ class EventBase : private boost::noncopyable,
   typedef LoopCallback::List LoopCallbackList;
   class FunctionRunner;
 
-  bool loopBody(int flags = 0);
+  bool loopBody(int flags = 0, bool ignoreKeepAlive = false);
 
   // executes any callbacks queued by runInLoop(); returns false if none found
   bool runLoopCallbacks();