fix folly::FunctionScheduler.cancelFunctionAndWait() hanging issue

[folly.git] / folly / experimental / FunctionScheduler.cpp

diff --git a/folly/experimental/FunctionScheduler.cpp b/folly/experimental/FunctionScheduler.cpp
index 98bd9ed71e85c8d3b2b0bbbe30d82b3c4db49649..2a94501523340d28c82ddc07afbbdee20236cc1e 100644 (file)
--- a/folly/experimental/FunctionScheduler.cpp
+++ b/folly/experimental/FunctionScheduler.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -63,7 +63,7 @@ struct PoissonDistributionFunctor {
 
 struct UniformDistributionFunctor {
   std::default_random_engine generator;
-  std::uniform_int_distribution<> dist;
+  std::uniform_int_distribution<milliseconds::rep> dist;
 
   UniformDistributionFunctor(milliseconds minInterval, milliseconds maxInterval)
       : generator(Random::rand32()),
@@ -213,13 +213,41 @@ void FunctionScheduler::addFunctionInternal(
           runOnce));
 }
 
-bool FunctionScheduler::cancelFunction(StringPiece nameID) {
-  std::unique_lock<std::mutex> l(mutex_);
-
+bool FunctionScheduler::cancelFunctionWithLock(
+    std::unique_lock<std::mutex>& lock,
+    StringPiece nameID) {
+  CHECK_EQ(lock.owns_lock(), true);
   if (currentFunction_ && currentFunction_->name == nameID) {
     // This function is currently being run. Clear currentFunction_
     // The running thread will see this and won't reschedule the function.
     currentFunction_ = nullptr;
+    cancellingCurrentFunction_ = true;
+    return true;
+  }
+  return false;
+}
+
+bool FunctionScheduler::cancelFunction(StringPiece nameID) {
+  std::unique_lock<std::mutex> l(mutex_);
+
+  if (cancelFunctionWithLock(l, nameID)) {
+    return true;
+  }
+
+  for (auto it = functions_.begin(); it != functions_.end(); ++it) {
+    if (it->isValid() && it->name == nameID) {
+      cancelFunction(l, it);
+      return true;
+    }
+  }
+  return false;
+}
+
+bool FunctionScheduler::cancelFunctionAndWait(StringPiece nameID) {
+  std::unique_lock<std::mutex> l(mutex_);
+
+  if (cancelFunctionWithLock(l, nameID)) {
+    runningCondvar_.wait(l, [this]() { return !cancellingCurrentFunction_; });
     return true;
   }
 
@@ -253,10 +281,27 @@ void FunctionScheduler::cancelFunction(const std::unique_lock<std::mutex>& l,
   }
 }
 
-void FunctionScheduler::cancelAllFunctions() {
-  std::unique_lock<std::mutex> l(mutex_);
+bool FunctionScheduler::cancelAllFunctionsWithLock(
+    std::unique_lock<std::mutex>& lock) {
+  CHECK_EQ(lock.owns_lock(), true);
   functions_.clear();
+  if (currentFunction_) {
+    cancellingCurrentFunction_ = true;
+  }
   currentFunction_ = nullptr;
+  return cancellingCurrentFunction_;
+}
+
+void FunctionScheduler::cancelAllFunctions() {
+  std::unique_lock<std::mutex> l(mutex_);
+  cancelAllFunctionsWithLock(l);
+}
+
+void FunctionScheduler::cancelAllFunctionsAndWait() {
+  std::unique_lock<std::mutex> l(mutex_);
+  if (cancelAllFunctionsWithLock(l)) {
+    runningCondvar_.wait(l, [this]() { return !cancellingCurrentFunction_; });
+  }
 }
 
 bool FunctionScheduler::resetFunctionTimer(StringPiece nameID) {
@@ -291,8 +336,6 @@ bool FunctionScheduler::start() {
     return false;
   }
 
-  running_ = true;
-
   VLOG(1) << "Starting FunctionScheduler with " << functions_.size()
           << " functions.";
   auto now = steady_clock::now();
@@ -307,6 +350,8 @@ bool FunctionScheduler::start() {
   std::make_heap(functions_.begin(), functions_.end(), fnCmp_);
 
   thread_ = std::thread([&] { this->run(); });
+  running_ = true;
+
   return true;
 }
 
@@ -355,6 +400,7 @@ void FunctionScheduler::run() {
     if (sleepTime < milliseconds::zero()) {
       // We need to run this function now
       runOneFunction(lock, now);
+      runningCondvar_.notify_all();
     } else {
       // Re-add the function to the heap, and wait until we actually
       // need to run it.
@@ -413,10 +459,12 @@ void FunctionScheduler::runOneFunction(std::unique_lock<std::mutex>& lock,
   if (!currentFunction_) {
     // The function was cancelled while we were running it.
     // We shouldn't reschedule it;
+    cancellingCurrentFunction_ = false;
     return;
   }
   if (currentFunction_->runOnce) {
     // Don't reschedule if the function only needed to run once.
+    currentFunction_ = nullptr;
     return;
   }
   // Clear currentFunction_