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 6dfb2c2c76f0b9a53c536f749020b8377652336e..2a94501523340d28c82ddc07afbbdee20236cc1e 100644 (file)
--- a/folly/experimental/FunctionScheduler.cpp
+++ b/folly/experimental/FunctionScheduler.cpp
@@ -213,13 +213,24 @@ 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;
   }
 
@@ -235,11 +246,9 @@ bool FunctionScheduler::cancelFunction(StringPiece nameID) {
 bool FunctionScheduler::cancelFunctionAndWait(StringPiece nameID) {
   std::unique_lock<std::mutex> l(mutex_);
 
-  auto* currentFunction = currentFunction_;
-  if (currentFunction && currentFunction->name == nameID) {
-    runningCondvar_.wait(l, [currentFunction, this]() {
-      return currentFunction != currentFunction_;
-    });
+  if (cancelFunctionWithLock(l, nameID)) {
+    runningCondvar_.wait(l, [this]() { return !cancellingCurrentFunction_; });
+    return true;
   }
 
   for (auto it = functions_.begin(); it != functions_.end(); ++it) {
@@ -272,18 +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 (currentFunction_) {
-    runningCondvar_.wait(l, [this]() { return currentFunction_ == nullptr; });
+  if (cancelAllFunctionsWithLock(l)) {
+    runningCondvar_.wait(l, [this]() { return !cancellingCurrentFunction_; });
   }
-  functions_.clear();
 }
 
 bool FunctionScheduler::resetFunctionTimer(StringPiece nameID) {
@@ -318,8 +336,6 @@ bool FunctionScheduler::start() {
     return false;
   }
 
-  running_ = true;
-
   VLOG(1) << "Starting FunctionScheduler with " << functions_.size()
           << " functions.";
   auto now = steady_clock::now();
@@ -334,6 +350,8 @@ bool FunctionScheduler::start() {
   std::make_heap(functions_.begin(), functions_.end(), fnCmp_);
 
   thread_ = std::thread([&] { this->run(); });
+  running_ = true;
+
   return true;
 }
 
@@ -441,10 +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_