From 70eccdc7275eecd3ca8241910b9f7dc95ebdef9d Mon Sep 17 00:00:00 2001
From: Lang Hames <lhames@gmail.com>
Date: Sun, 23 Apr 2017 23:36:13 +0000
Subject: [PATCH] [Orc] Use recursive mutexes for Error serialization.

Errors can be nested, so we need recursive locking for serialization /
deserialization.

llvm-svn: 301147
---
 .../llvm/ExecutionEngine/Orc/RPCSerialization.h    | 67 +++++++++++++---------
 1 file changed, 39 insertions(+), 28 deletions(-)

diff --git a/llvm/include/llvm/ExecutionEngine/Orc/RPCSerialization.h b/llvm/include/llvm/ExecutionEngine/Orc/RPCSerialization.h
index 84a037b..a300845 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/RPCSerialization.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/RPCSerialization.h
@@ -348,7 +348,7 @@ public:
       // key of the deserializers map to save us from duplicating the string in
       // the serializer. This should be changed to use a stringpool if we switch
       // to a map type that may move keys in memory.
-      std::lock_guard<std::mutex> Lock(DeserializersMutex);
+      std::lock_guard<std::recursive_mutex> Lock(DeserializersMutex);
       auto I =
         Deserializers.insert(Deserializers.begin(),
                              std::make_pair(std::move(Name),
@@ -358,7 +358,7 @@ public:
     
     {
       assert(KeyName != nullptr && "No keyname pointer");
-      std::lock_guard<std::mutex> Lock(SerializersMutex);
+      std::lock_guard<std::recursive_mutex> Lock(SerializersMutex);
       // FIXME: Move capture Serialize once we have C++14.
       Serializers[ErrorInfoT::classID()] =
 	[KeyName, Serialize](ChannelT &C, const ErrorInfoBase &EIB) -> Error {
@@ -372,12 +372,13 @@ public:
   }
   
   static Error serialize(ChannelT &C, Error &&Err) {
-    std::lock_guard<std::mutex> Lock(SerializersMutex);
+    std::lock_guard<std::recursive_mutex> Lock(SerializersMutex);
+
     if (!Err)
       return serializeSeq(C, std::string());
 
     return handleErrors(std::move(Err),
-                        [&C](const ErrorInfoBase &EIB) {
+                        [&C, &Lock](const ErrorInfoBase &EIB) {
                           auto SI = Serializers.find(EIB.dynamicClassID());
                           if (SI == Serializers.end())
                             return serializeAsStringError(C, EIB);
@@ -386,7 +387,7 @@ public:
   }
 
   static Error deserialize(ChannelT &C, Error &Err) {
-    std::lock_guard<std::mutex> Lock(DeserializersMutex);
+    std::lock_guard<std::recursive_mutex> Lock(DeserializersMutex);
 
     std::string Key;
     if (auto Err = deserializeSeq(C, Key))
@@ -406,8 +407,6 @@ public:
 private:
 
   static Error serializeAsStringError(ChannelT &C, const ErrorInfoBase &EIB) {
-    assert(EIB.dynamicClassID() != StringError::classID() &&
-           "StringError serialization not registered");
     std::string ErrMsg;
     {
       raw_string_ostream ErrMsgStream(ErrMsg);
@@ -417,17 +416,17 @@ private:
                                                 inconvertibleErrorCode()));
   }
 
-  static std::mutex SerializersMutex;
-  static std::mutex DeserializersMutex;
+  static std::recursive_mutex SerializersMutex;
+  static std::recursive_mutex DeserializersMutex;
   static std::map<const void*, WrappedErrorSerializer> Serializers;
   static std::map<std::string, WrappedErrorDeserializer> Deserializers;
 };
 
 template <typename ChannelT>
-std::mutex SerializationTraits<ChannelT, Error>::SerializersMutex;
+std::recursive_mutex SerializationTraits<ChannelT, Error>::SerializersMutex;
 
 template <typename ChannelT>
-std::mutex SerializationTraits<ChannelT, Error>::DeserializersMutex;
+std::recursive_mutex SerializationTraits<ChannelT, Error>::DeserializersMutex;
 
 template <typename ChannelT>
 std::map<const void*,
@@ -439,27 +438,39 @@ std::map<std::string,
          typename SerializationTraits<ChannelT, Error>::WrappedErrorDeserializer>
 SerializationTraits<ChannelT, Error>::Deserializers;
 
+/// Registers a serializer and deserializer for the given error type on the
+/// given channel type.
+template <typename ChannelT, typename ErrorInfoT, typename SerializeFtor,
+          typename DeserializeFtor>
+void registerErrorSerialization(std::string Name, SerializeFtor &&Serialize,
+                                DeserializeFtor &&Deserialize) {
+  SerializationTraits<ChannelT, Error>::template registerErrorType<ErrorInfoT>(
+    std::move(Name),
+    std::forward<SerializeFtor>(Serialize),
+    std::forward<DeserializeFtor>(Deserialize));
+}
+
+/// Registers serialization/deserialization for StringError.
 template <typename ChannelT>
 void registerStringError() {
   static bool AlreadyRegistered = false;
   if (!AlreadyRegistered) {
-    SerializationTraits<ChannelT, Error>::
-      template registerErrorType<StringError>(
-        "StringError",
-        [](ChannelT &C, const StringError &SE) {
-          return serializeSeq(C, SE.getMessage());
-        },
-        [](ChannelT &C, Error &Err) {
-          ErrorAsOutParameter EAO(&Err);
-          std::string Msg;
-          if (auto E2 = deserializeSeq(C, Msg))
-            return E2;
-          Err =
-            make_error<StringError>(std::move(Msg),
-                                    orcError(
-                                      OrcErrorCode::UnknownErrorCodeFromRemote));
-          return Error::success();
-        });
+    registerErrorSerialization<ChannelT, StringError>(
+      "StringError",
+      [](ChannelT &C, const StringError &SE) {
+        return serializeSeq(C, SE.getMessage());
+      },
+      [](ChannelT &C, Error &Err) -> Error {
+        ErrorAsOutParameter EAO(&Err);
+        std::string Msg;
+        if (auto E2 = deserializeSeq(C, Msg))
+          return E2;
+        Err =
+          make_error<StringError>(std::move(Msg),
+                                  orcError(
+                                    OrcErrorCode::UnknownErrorCodeFromRemote));
+        return Error::success();
+      });
     AlreadyRegistered = true;
   }
 }
-- 
2.7.4