Remove generation of RCL allocators from C++.

As explained in ros2#1254, there's conceptually no way to implement RCL
allocators in terms of C++ allocators. Since allocator_common can't
be fixed, delete it and inline calls to rcl_get_default_allocator at
the call sites. Since this would introduce surprising behavior for
custom allocator users (using system malloc when a custom allocator
is requested), add compile-time assertions checking for non-default
allocators. Since there's other blocking bugs for allocator use
(ros2#1061), this shouldn't break existing users.

Technically, we could roll back a lot of templating on allocator and
explicitly use std::allocator<void> in all classes. I have refrained
from doing so because you might have plans with this code, but if you
concur, I'll be more than happy to de-template all these classes to
simplify the code.

Author: stevewolter

rclcpp/include/rclcpp/allocator/allocator_common.hpp

@@ -17,8 +17,6 @@
 
 #include <memory>
 
-#include "rcl/allocator.h"
-
 #include "rclcpp/allocator/allocator_deleter.hpp"
 
 namespace rclcpp
@@ -29,70 +27,6 @@ namespace allocator
 template<typename T, typename Alloc>
 using AllocRebind = typename std::allocator_traits<Alloc>::template rebind_traits<T>;
 
-template<typename Alloc>
-void * retyped_allocate(size_t size, void * untyped_allocator)
-{
-  auto typed_allocator = static_cast<Alloc *>(untyped_allocator);
-  if (!typed_allocator) {
-    throw std::runtime_error("Received incorrect allocator type");
-  }
-  return std::allocator_traits<Alloc>::allocate(*typed_allocator, size);
-}
-
-template<typename T, typename Alloc>
-void retyped_deallocate(void * untyped_pointer, void * untyped_allocator)
-{
-  auto typed_allocator = static_cast<Alloc *>(untyped_allocator);
-  if (!typed_allocator) {
-    throw std::runtime_error("Received incorrect allocator type");
-  }
-  auto typed_ptr = static_cast<T *>(untyped_pointer);
-  std::allocator_traits<Alloc>::deallocate(*typed_allocator, typed_ptr, 1);
-}
-
-template<typename T, typename Alloc>
-void * retyped_reallocate(void * untyped_pointer, size_t size, void * untyped_allocator)
-{
-  auto typed_allocator = static_cast<Alloc *>(untyped_allocator);
-  if (!typed_allocator) {
-    throw std::runtime_error("Received incorrect allocator type");
-  }
-  auto typed_ptr = static_cast<T *>(untyped_pointer);
-  std::allocator_traits<Alloc>::deallocate(*typed_allocator, typed_ptr, 1);
-  return std::allocator_traits<Alloc>::allocate(*typed_allocator, size);
-}
-
-
-// Convert a std::allocator_traits-formatted Allocator into an rcl allocator
-template<
-  typename T,
-  typename Alloc,
-  typename std::enable_if<!std::is_same<Alloc, std::allocator<void>>::value>::type * = nullptr>
-rcl_allocator_t get_rcl_allocator(Alloc & allocator)
-{
-  rcl_allocator_t rcl_allocator = rcl_get_default_allocator();
-#ifndef _WIN32
-  rcl_allocator.allocate = &retyped_allocate<Alloc>;
-  rcl_allocator.deallocate = &retyped_deallocate<T, Alloc>;
-  rcl_allocator.reallocate = &retyped_reallocate<T, Alloc>;
-  rcl_allocator.state = &allocator;
-#else
-  (void)allocator;  // Remove warning
-#endif
-  return rcl_allocator;
-}
-
-// TODO(jacquelinekay) Workaround for an incomplete implementation of std::allocator<void>
-template<
-  typename T,
-  typename Alloc,
-  typename std::enable_if<std::is_same<Alloc, std::allocator<void>>::value>::type * = nullptr>
-rcl_allocator_t get_rcl_allocator(Alloc & allocator)
-{
-  (void)allocator;
-  return rcl_get_default_allocator();
-}
-
 }  // namespace allocator
 }  // namespace rclcpp
 

rclcpp/include/rclcpp/message_memory_strategy.hpp

@@ -20,7 +20,7 @@
 
 #include "rcl/types.h"
 
-#include "rclcpp/allocator/allocator_common.hpp"
+#include "rcl/allocator.h"
 #include "rclcpp/exceptions.hpp"
 #include "rclcpp/macros.hpp"
 #include "rclcpp/serialized_message.hpp"
@@ -61,15 +61,19 @@ class MessageMemoryStrategy
     message_allocator_ = std::make_shared<MessageAlloc>();
     serialized_message_allocator_ = std::make_shared<SerializedMessageAlloc>();
     buffer_allocator_ = std::make_shared<BufferAlloc>();
-    rcutils_allocator_ = allocator::get_rcl_allocator<char, BufferAlloc>(*buffer_allocator_.get());
+    // The rcl allocator interface is incompatible with C++ allocators
+    static_assert(std::is_same<Alloc, std::allocator<void>>::value, "Non-default allocators are not supported");
+    rcutils_allocator_ = rcl_get_default_allocator();
   }
 
   explicit MessageMemoryStrategy(std::shared_ptr<Alloc> allocator)
   {
     message_allocator_ = std::make_shared<MessageAlloc>(*allocator.get());
     serialized_message_allocator_ = std::make_shared<SerializedMessageAlloc>(*allocator.get());
     buffer_allocator_ = std::make_shared<BufferAlloc>(*allocator.get());
-    rcutils_allocator_ = allocator::get_rcl_allocator<char, BufferAlloc>(*buffer_allocator_.get());
+    // The rcl allocator interface is incompatible with C++ allocators
+    static_assert(std::is_same<Alloc, std::allocator<void>>::value, "Non-default allocators are not supported");
+    rcutils_allocator_ = rcl_get_default_allocator();
   }
 
   virtual ~MessageMemoryStrategy() = default;

rclcpp/include/rclcpp/publisher_options.hpp

@@ -19,9 +19,9 @@
 #include <string>
 #include <vector>
 
+#include "rcl/allocator.h"
 #include "rcl/publisher.h"
 
-#include "rclcpp/allocator/allocator_common.hpp"
 #include "rclcpp/detail/rmw_implementation_specific_publisher_payload.hpp"
 #include "rclcpp/intra_process_setting.hpp"
 #include "rclcpp/qos.hpp"
@@ -72,10 +72,9 @@ struct PublisherOptionsWithAllocator : public PublisherOptionsBase
   to_rcl_publisher_options(const rclcpp::QoS & qos) const
   {
     rcl_publisher_options_t result = rcl_publisher_get_default_options();
-    using AllocatorTraits = std::allocator_traits<Allocator>;
-    using MessageAllocatorT = typename AllocatorTraits::template rebind_alloc<MessageT>;
-    auto message_alloc = std::make_shared<MessageAllocatorT>(*this->get_allocator().get());
-    result.allocator = rclcpp::allocator::get_rcl_allocator<MessageT>(*message_alloc);
+    // The rcl allocator interface is incompatible with C++ allocators
+    static_assert(std::is_same<Allocator, std::allocator<void>>::value, "Non-default allocators are not supported");
+    result.allocator = rcl_get_default_allocator();
     result.qos = qos.get_rmw_qos_profile();
 
     // Apply payload to rcl_publisher_options if necessary.

rclcpp/include/rclcpp/strategies/allocator_memory_strategy.hpp

@@ -20,7 +20,6 @@
 
 #include "rcl/allocator.h"
 
-#include "rclcpp/allocator/allocator_common.hpp"
 #include "rclcpp/memory_strategy.hpp"
 #include "rclcpp/node.hpp"
 #include "rclcpp/visibility_control.hpp"
@@ -437,7 +436,7 @@ class AllocatorMemoryStrategy : public memory_strategy::MemoryStrategy
 
   rcl_allocator_t get_allocator() override
   {
-    return rclcpp::allocator::get_rcl_allocator<void *, VoidAlloc>(*allocator_.get());
+    return rcl_get_default_allocator();
   }
 
   size_t number_of_ready_subscriptions() const override

rclcpp/include/rclcpp/subscription_options.hpp

@@ -20,6 +20,8 @@
 #include <string>
 #include <vector>
 
+#include "rcl/allocator.h"
+
 #include "rclcpp/callback_group.hpp"
 #include "rclcpp/detail/rmw_implementation_specific_subscription_payload.hpp"
 #include "rclcpp/intra_process_buffer_type.hpp"
@@ -99,10 +101,9 @@ struct SubscriptionOptionsWithAllocator : public SubscriptionOptionsBase
   to_rcl_subscription_options(const rclcpp::QoS & qos) const
   {
     rcl_subscription_options_t result = rcl_subscription_get_default_options();
-    using AllocatorTraits = std::allocator_traits<Allocator>;
-    using MessageAllocatorT = typename AllocatorTraits::template rebind_alloc<MessageT>;
-    auto message_alloc = std::make_shared<MessageAllocatorT>(*allocator.get());
-    result.allocator = allocator::get_rcl_allocator<MessageT>(*message_alloc);
+    // The rcl allocator interface is incompatible with C++ allocators
+    static_assert(std::is_same<Allocator, std::allocator<void>>::value, "Non-default allocators are not supported");
+    result.allocator = rcl_get_default_allocator();
     result.qos = qos.get_rmw_qos_profile();
     result.rmw_subscription_options.ignore_local_publications = this->ignore_local_publications;