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ProxyClientBase: avoid static_cast to partially destructed object #127

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Merged
ryanofsky merged 1 commit into from
Jan 16, 2025
Merged

ProxyClientBase: avoid static_cast to partially destructed object #127

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7 changes: 4 additions & 3 deletions include/mp/proxy-io.h
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Original file line number Diff line number Diff line change
Expand Up @@ -382,7 +382,7 @@ ProxyClientBase<Interface, Impl>::ProxyClientBase(typename Interface::Client cli
auto cleanup = m_context.connection->addSyncCleanup([this]() {
// Release client capability by move-assigning to temporary.
{
typename Interface::Client(std::move(self().m_client));
typename Interface::Client(std::move(m_client));
}
{
std::unique_lock<std::mutex> lock(m_context.connection->m_loop.m_mutex);
Expand Down Expand Up @@ -412,13 +412,13 @@ ProxyClientBase<Interface, Impl>::ProxyClientBase(typename Interface::Client cli
// the remote object, waiting for it to be deleted server side. If the
// capnp interface does not define a destroy method, this will just call
// an empty stub defined in the ProxyClientBase class and do nothing.
self().destroy();
Sub::destroy(*this);

// FIXME: Could just invoke removed addCleanup fn here instead of duplicating code
m_context.connection->m_loop.sync([&]() {
// Release client capability by move-assigning to temporary.
{
typename Interface::Client(std::move(self().m_client));
typename Interface::Client(std::move(m_client));
}
{
std::unique_lock<std::mutex> lock(m_context.connection->m_loop.m_mutex);
Expand All @@ -432,6 +432,7 @@ ProxyClientBase<Interface, Impl>::ProxyClientBase(typename Interface::Client cli
});
}
});
Sub::construct(*this);
}

template <typename Interface, typename Impl>
Expand Down
8 changes: 4 additions & 4 deletions include/mp/proxy.h
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Expand Up @@ -56,6 +56,8 @@ class ProxyClientBase : public Impl_
public:
using Interface = Interface_;
using Impl = Impl_;
using Sub = ProxyClient<Interface>;
using Super = ProxyClientBase<Interface, Impl>;

ProxyClientBase(typename Interface::Client client, Connection* connection, bool destroy_connection);
~ProxyClientBase() noexcept;
Expand Down Expand Up @@ -89,10 +91,8 @@ class ProxyClientBase : public Impl_
// then it will also ensure that the destructor runs on the same thread the
// client used to make other RPC calls, instead of running on the server
// EventLoop thread and possibly blocking it.
void construct() {}
void destroy() {}

ProxyClient<Interface>& self() { return static_cast<ProxyClient<Interface>&>(*this); }
static void construct(Super&) {}
static void destroy(Super&) {}

typename Interface::Client m_client;
ProxyContext m_context;
Expand Down
15 changes: 9 additions & 6 deletions src/mp/gen.cpp
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Expand Up @@ -357,8 +357,7 @@ void Generate(kj::StringPtr src_prefix,
client << "public ProxyClientCustom<" << message_namespace << "::" << node_name << ", "
<< proxied_class_type << ">\n{\n";
client << "public:\n";
client << " template <typename... Args>\n";
client << " ProxyClient(Args&&... args) : ProxyClientCustom(std::forward<Args>(args)...) { construct(); }\n";
client << " using ProxyClientCustom::ProxyClientCustom;\n";
client << " ~ProxyClient();\n";

std::ostringstream server;
Expand Down Expand Up @@ -531,18 +530,22 @@ void Generate(kj::StringPtr src_prefix,
server_invoke_end << ")";
}

std::string static_str{is_construct || is_destroy ? "static " : ""};
std::string super_str{is_construct || is_destroy ? "Super& super" : ""};
std::string self_str{is_construct || is_destroy ? "super" : "*this"};

client << " using M" << method_ordinal << " = ProxyClientMethodTraits<" << method_prefix
<< "Params>;\n";
client << " typename M" << method_ordinal << "::Result " << method_name << "("
<< client_args.str() << ")";
client << " " << static_str << "typename M" << method_ordinal << "::Result " << method_name << "("
<< super_str << client_args.str() << ")";
client << ";\n";
def_client << "ProxyClient<" << message_namespace << "::" << node_name << ">::M" << method_ordinal
<< "::Result ProxyClient<" << message_namespace << "::" << node_name << ">::" << method_name
<< "(" << client_args.str() << ") {\n";
<< "(" << super_str << client_args.str() << ") {\n";
if (has_result) {
def_client << " typename M" << method_ordinal << "::Result result;\n";
}
def_client << " clientInvoke(*this, &" << message_namespace << "::" << node_name
def_client << " clientInvoke(" << self_str << ", &" << message_namespace << "::" << node_name
<< "::Client::" << method_name << "Request" << client_invoke.str() << ");\n";
if (has_result) def_client << " return result;\n";
def_client << "}\n";
Expand Down