From 6108cf3eb7aa29d201f8829fa44a6ec2a31c8609 Mon Sep 17 00:00:00 2001
From: Vinnie Falco <vinnie.falco@gmail.com>
Date: Sun, 29 Apr 2018 15:01:22 -0700
Subject: [PATCH] Add flat_stream to experimental:

This adds a new stream wrapper class template designed to address
a performance shortcoming of boost::asio::ssl::stream.
---
 CHANGELOG.md                                  |   6 +
 doc/qbk/02_examples.qbk                       |  10 -
 doc/qbk/quickref.xml                          |  20 +
 doc/source.dox                                |   1 +
 example/advanced/server-flex/CMakeLists.txt   |   1 -
 example/common/flat_stream.hpp                | 506 ------------------
 example/common/ssl_stream.hpp                 | 329 ------------
 .../experimental/core/detail/flat_stream.hpp  |  64 +++
 .../beast/experimental/core/flat_stream.hpp   | 353 ++++++++++++
 .../experimental/core/impl/flat_stream.ipp    | 304 +++++++++++
 test/beast/CMakeLists.txt                     |   1 +
 test/beast/Jamfile                            |   2 +
 test/beast/experimental/CMakeLists.txt        |  23 +
 test/beast/experimental/Jamfile               |  25 +
 .../experimental}/flat_stream.cpp             |   4 +-
 test/example/common/CMakeLists.txt            |   1 -
 test/example/common/Jamfile                   |   1 -
 17 files changed, 801 insertions(+), 850 deletions(-)
 delete mode 100644 example/common/flat_stream.hpp
 delete mode 100644 example/common/ssl_stream.hpp
 create mode 100644 include/boost/beast/experimental/core/detail/flat_stream.hpp
 create mode 100644 include/boost/beast/experimental/core/flat_stream.hpp
 create mode 100644 include/boost/beast/experimental/core/impl/flat_stream.ipp
 create mode 100644 test/beast/experimental/CMakeLists.txt
 create mode 100644 test/beast/experimental/Jamfile
 rename test/{example/common => beast/experimental}/flat_stream.cpp (95%)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6f4d426d..f86b9fac 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,9 @@
+Version 170:
+
+* Add flat_stream to experimental
+
+--------------------------------------------------------------------------------
+
 Version 169:
 
 * Use buffers_to_string in tests
diff --git a/doc/qbk/02_examples.qbk b/doc/qbk/02_examples.qbk
index 5b757206..22d0fb14 100644
--- a/doc/qbk/02_examples.qbk
+++ b/doc/qbk/02_examples.qbk
@@ -216,16 +216,6 @@ listed here along with a description of their use:
         in the documentation. It is used by the "flex" servers which
         support both plain and SSL sessions on the same port.
     ]
-][
-    [[source_file example/common/flat_stream.hpp]]
-    [
-        This wrapper flattens buffer sequences having length greater than 1
-        and total size below a predefined amount, using a dynamic memory
-        allocation. It is primarily designed to overcome a performance
-        limitation of the current Boost.Asio version of `ssl::stream`, which
-        does not use OpenSSL's scatter/gather interface for its primitive
-        read and write operations.
-    ]
 ][
     [[source_file example/common/root_certificates.hpp]]
     [
diff --git a/doc/qbk/quickref.xml b/doc/qbk/quickref.xml
index f3681dc7..91c92c1a 100644
--- a/doc/qbk/quickref.xml
+++ b/doc/qbk/quickref.xml
@@ -284,6 +284,26 @@
       </row>
     </tbody>
   </tgroup>
+  <tgroup cols="1">
+    <colspec colname="a"/>
+    <thead>
+      <row>
+        <entry valign="center" namest="a" nameend="c">
+          <bridgehead renderas="sect2">Experimental</bridgehead>
+        </entry>
+      </row>
+    </thead>
+    <tbody>
+      <row>
+        <entry valign="top">
+          <bridgehead renderas="sect3">Classes</bridgehead>
+          <simplelist type="vert" columns="1">
+            <member><link linkend="beast.ref.boost__beast__flat_stream">flat_stream</link></member>
+          </simplelist>
+        </entry>
+      </row>
+    </tbody>
+  </tgroup>
 <!--
   <tgroup cols="1">
     <colspec colname="a"/>
diff --git a/doc/source.dox b/doc/source.dox
index 4d9d07ad..a543f8be 100644
--- a/doc/source.dox
+++ b/doc/source.dox
@@ -105,6 +105,7 @@ WARN_LOGFILE           =
 INPUT = \
         $(LIB_DIR)/include/boost/beast/ \
         $(LIB_DIR)/include/boost/beast/core \
+        $(LIB_DIR)/include/boost/beast/experimental/core \
         $(LIB_DIR)/include/boost/beast/http \
         $(LIB_DIR)/include/boost/beast/websocket \
         $(LIB_DIR)/include/boost/beast/zlib
diff --git a/example/advanced/server-flex/CMakeLists.txt b/example/advanced/server-flex/CMakeLists.txt
index 3c607733..21b5f9cb 100644
--- a/example/advanced/server-flex/CMakeLists.txt
+++ b/example/advanced/server-flex/CMakeLists.txt
@@ -15,7 +15,6 @@ if (OPENSSL_FOUND)
     add_executable (advanced-server-flex
         ${BOOST_BEAST_FILES}
         ${PROJECT_SOURCE_DIR}/example/common/detect_ssl.hpp
-        ${PROJECT_SOURCE_DIR}/example/common/flat_stream.hpp
         ${PROJECT_SOURCE_DIR}/example/common/server_certificate.hpp
         ${PROJECT_SOURCE_DIR}/example/common/ssl_stream.hpp
         Jamfile
diff --git a/example/common/flat_stream.hpp b/example/common/flat_stream.hpp
deleted file mode 100644
index d7f08540..00000000
--- a/example/common/flat_stream.hpp
+++ /dev/null
@@ -1,506 +0,0 @@
-//
-// Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-// Official repository: https://github.com/boostorg/beast
-//
-
-#ifndef BOOST_BEAST_EXAMPLE_COMMON_FLAT_STREAM_HPP
-#define BOOST_BEAST_EXAMPLE_COMMON_FLAT_STREAM_HPP
-
-#include <boost/beast/core/buffers_prefix.hpp>
-#include <boost/beast/core/error.hpp>
-#include <boost/beast/core/handler_ptr.hpp>
-#include <boost/beast/core/type_traits.hpp>
-#include <boost/beast/websocket/teardown.hpp>
-#include <boost/asio/associated_allocator.hpp>
-#include <boost/asio/associated_executor.hpp>
-#include <boost/asio/buffer.hpp>
-#include <boost/asio/coroutine.hpp>
-#include <boost/asio/executor_work_guard.hpp>
-#include <boost/asio/handler_continuation_hook.hpp>
-#include <boost/asio/handler_invoke_hook.hpp>
-#include <boost/throw_exception.hpp>
-#include <iterator>
-#include <memory>
-#include <utility>
-
-namespace detail {
-
-class flat_stream_base
-{
-public:
-    static std::size_t constexpr coalesce_limit = 64 * 1024;
-
-    // calculates the coalesce settings for a buffer sequence
-    template<class BufferSequence>
-    static
-    std::pair<std::size_t, bool>
-    coalesce(BufferSequence const& buffers, std::size_t limit)
-    {
-        std::pair<std::size_t, bool> result{0, false};
-        auto first = boost::asio::buffer_sequence_begin(buffers);
-        auto last = boost::asio::buffer_sequence_end(buffers);
-        if(first != last)
-        {
-            result.first = boost::asio::buffer_size(*first);
-            if(result.first < limit)
-            {
-                auto it = first;
-                auto prev = first;
-                while(++it != last)
-                {
-                    auto const n =
-                        boost::asio::buffer_size(*it);
-                    if(result.first + n > limit)
-                        break;
-                    result.first += n;
-                    prev = it;
-                }
-                result.second = prev != first;
-            }
-        }
-        return result;
-    }
-};
-
-} // detail
-
-/** Flat stream wrapper.
-
-    This wrapper flattens buffer sequences having length greater than 1
-    and total size below a predefined amount, using a dynamic memory
-    allocation. It is primarily designed to overcome a performance
-    limitation of the current Boost.Asio version of ssl::stream, which
-    does not use OpenSSL's scatter/gather interface for its primitive
-    read and write operations.
-
-    See:
-        https://github.com/boostorg/beast/issues/1108
-        https://github.com/boostorg/asio/issues/100
-        https://stackoverflow.com/questions/38198638/openssl-ssl-write-from-multiple-buffers-ssl-writev
-        https://stackoverflow.com/questions/50026167/performance-drop-on-port-from-beast-1-0-0-b66-to-boost-1-67-0-beast
-*/
-template<class NextLayer>
-class flat_stream : private detail::flat_stream_base
-{
-    // Largest buffer size we will flatten
-    static std::size_t constexpr max_size = 1024 * 1024;
-
-    template<class, class> class write_op;
-
-    NextLayer stream_;
-
-public:
-    /// The type of the next layer.
-    using next_layer_type =
-        typename std::remove_reference<NextLayer>::type;
-
-    /// The type of the lowest layer.
-    using lowest_layer_type = boost::beast::get_lowest_layer<next_layer_type>;
-
-    /// The type of the executor associated with the object.
-    using executor_type = typename next_layer_type::executor_type;
-
-    ~flat_stream() = default;
-    flat_stream(flat_stream&&) = default;
-    flat_stream(flat_stream const&) = delete;
-    flat_stream& operator=(flat_stream&&) = default;
-    flat_stream& operator=(flat_stream const&) = delete;
-
-    /** Constructor
-
-        Arguments, if any, are forwarded to the next layer's constructor.
-    */
-    template<class... Args>
-    explicit
-    flat_stream(Args&&... args);
-
-    //--------------------------------------------------------------------------
-
-    /** Get the executor associated with the object.
-    
-        This function may be used to obtain the executor object that the
-        stream uses to dispatch handlers for asynchronous operations.
-
-        @return A copy of the executor that stream will use to dispatch handlers.
-    */
-    executor_type
-    get_executor() noexcept
-    {
-        return stream_.get_executor();
-    }
-
-    /** Get a reference to the next layer
-
-        This function returns a reference to the next layer
-        in a stack of stream layers.
-
-        @return A reference to the next layer in the stack of
-        stream layers.
-    */
-    next_layer_type&
-    next_layer()
-    {
-        return stream_;
-    }
-
-    /** Get a reference to the next layer
-
-        This function returns a reference to the next layer in a
-        stack of stream layers.
-
-        @return A reference to the next layer in the stack of
-        stream layers.
-    */
-    next_layer_type const&
-    next_layer() const
-    {
-        return stream_;
-    }
-
-    /** Get a reference to the lowest layer
-
-        This function returns a reference to the lowest layer
-        in a stack of stream layers.
-
-        @return A reference to the lowest layer in the stack of
-        stream layers.
-    */
-    lowest_layer_type&
-    lowest_layer()
-    {
-        return stream_.lowest_layer();
-    }
-
-    /** Get a reference to the lowest layer
-
-        This function returns a reference to the lowest layer
-        in a stack of stream layers.
-
-        @return A reference to the lowest layer in the stack of
-        stream layers. Ownership is not transferred to the caller.
-    */
-    lowest_layer_type const&
-    lowest_layer() const
-    {
-        return stream_.lowest_layer();
-    }
-
-    //--------------------------------------------------------------------------
-
-    template<class MutableBufferSequence>
-    std::size_t
-    read_some(MutableBufferSequence const& buffers);
-
-    template<class MutableBufferSequence>
-    std::size_t
-    read_some(
-        MutableBufferSequence const& buffers,
-        boost::system::error_code& ec);
-
-    template<class ConstBufferSequence>
-    std::size_t
-    write_some(ConstBufferSequence const& buffers);
-
-    template<class ConstBufferSequence>
-    std::size_t
-    write_some(
-        ConstBufferSequence const& buffers,
-        boost::system::error_code& ec);
-
-    template<
-        class MutableBufferSequence,
-        class ReadHandler>
-    BOOST_ASIO_INITFN_RESULT_TYPE(
-        ReadHandler, void(boost::system::error_code, std::size_t))
-    async_read_some(
-        MutableBufferSequence const& buffers,
-        ReadHandler&& handler);
-
-    template<
-        class ConstBufferSequence,
-        class WriteHandler>
-    BOOST_ASIO_INITFN_RESULT_TYPE(
-        WriteHandler, void(boost::system::error_code, std::size_t))
-    async_write_some(
-        ConstBufferSequence const& buffers,
-        WriteHandler&& handler);
-
-    template<class T>
-    friend
-    void
-    teardown(boost::beast::websocket::role_type,
-        flat_stream<T>& s, boost::system::error_code& ec);
-
-    template<class T, class TeardownHandler>
-    friend
-    void
-    async_teardown(boost::beast::websocket::role_type role,
-        flat_stream<T>& s, TeardownHandler&& handler);
-};
-
-//------------------------------------------------------------------------------
-
-template<class NextLayer>
-template<class ConstBufferSequence, class Handler>
-class flat_stream<NextLayer>::write_op
-    : public boost::asio::coroutine
-{
-    using alloc_type = typename 
-        boost::asio::associated_allocator_t<Handler>::template
-            rebind<char>::other;
-
-    struct deleter
-    {
-        alloc_type alloc;
-        std::size_t size = 0;
-
-        explicit
-        deleter(alloc_type const& alloc_)
-            : alloc(alloc_)
-        {
-        }
-
-        void
-        operator()(char* p)
-        {
-            alloc.deallocate(p, size);
-        }
-    };
-
-    flat_stream<NextLayer>& s_;
-    ConstBufferSequence b_;
-    std::unique_ptr<char, deleter> p_;
-    Handler h_;
-
-public:
-    template<class DeducedHandler>
-    write_op(
-        flat_stream<NextLayer>& s,
-        ConstBufferSequence const& b,
-        DeducedHandler&& h)
-        : s_(s)
-        , b_(b)
-        , p_(nullptr, deleter{
-            (boost::asio::get_associated_allocator)(h)})
-        , h_(std::forward<DeducedHandler>(h))
-    {
-    }
-
-    using allocator_type =
-        boost::asio::associated_allocator_t<Handler>;
-
-    allocator_type
-    get_allocator() const noexcept
-    {
-        return (boost::asio::get_associated_allocator)(h_);
-    }
-
-    using executor_type = boost::asio::associated_executor_t<
-        Handler, decltype(std::declval<NextLayer&>().get_executor())>;
-
-    executor_type
-    get_executor() const noexcept
-    {
-        return (boost::asio::get_associated_executor)(
-            h_, s_.get_executor());
-    }
-
-    void
-    operator()(
-        boost::system::error_code ec,
-        std::size_t bytes_transferred)
-    {
-        BOOST_ASIO_CORO_REENTER(*this)
-        {
-            BOOST_ASIO_CORO_YIELD
-            {
-                auto const result = coalesce(b_,  coalesce_limit);
-                if(result.second)
-                {
-                    p_.get_deleter().size = result.first;
-                    p_.reset(p_.get_deleter().alloc.allocate(
-                        p_.get_deleter().size));
-                    boost::asio::buffer_copy(
-                        boost::asio::buffer(
-                            p_.get(), p_.get_deleter().size),
-                        b_, result.first);
-                    s_.stream_.async_write_some(
-                        boost::asio::buffer(
-                            p_.get(), p_.get_deleter().size),
-                                std::move(*this));
-                }
-                else
-                {
-                    s_.stream_.async_write_some(
-                        boost::beast::buffers_prefix(result.first, b_),
-                            std::move(*this));
-                }
-            }
-            p_.reset();
-            h_(ec, bytes_transferred);
-        }
-    }
-
-    friend
-    bool asio_handler_is_continuation(write_op* op)
-    {
-        using boost::asio::asio_handler_is_continuation;
-        return asio_handler_is_continuation(
-                std::addressof(op->h_));
-    }
-
-    template<class Function>
-    friend
-    void asio_handler_invoke(Function&& f, write_op* op)
-    {
-        using boost::asio::asio_handler_invoke;
-        asio_handler_invoke(f, std::addressof(op->h_));
-    }
-};
-
-//------------------------------------------------------------------------------
-
-template<class NextLayer>
-template<class... Args>
-flat_stream<NextLayer>::
-flat_stream(Args&&... args)
-    : stream_(std::forward<Args>(args)...)
-{
-}
-
-template<class NextLayer>
-template<class MutableBufferSequence>
-std::size_t
-flat_stream<NextLayer>::
-read_some(MutableBufferSequence const& buffers)
-{
-    static_assert(boost::beast::is_sync_read_stream<next_layer_type>::value,
-        "SyncReadStream requirements not met");
-    static_assert(boost::asio::is_mutable_buffer_sequence<
-        MutableBufferSequence>::value,
-            "MutableBufferSequence requirements not met");
-    boost::system::error_code ec;
-    auto n = read_some(buffers, ec);
-    if(ec)
-        BOOST_THROW_EXCEPTION(boost::system::system_error{ec});
-    return n;
-}
-
-template<class NextLayer>
-template<class MutableBufferSequence>
-std::size_t
-flat_stream<NextLayer>::
-read_some(MutableBufferSequence const& buffers, boost::system::error_code& ec)
-{
-    return stream_.read_some(buffers, ec);
-}
-
-template<class NextLayer>
-template<class ConstBufferSequence>
-std::size_t
-flat_stream<NextLayer>::
-write_some(ConstBufferSequence const& buffers)
-{
-    static_assert(boost::beast::is_sync_write_stream<next_layer_type>::value,
-        "SyncWriteStream requirements not met");
-    static_assert(boost::asio::is_const_buffer_sequence<
-        ConstBufferSequence>::value,
-            "ConstBufferSequence requirements not met");
-    boost::system::error_code ec;
-    auto n = write_some(buffers, ec);
-    if(ec)
-        BOOST_THROW_EXCEPTION(boost::system::system_error{ec});
-    return n;
-}
-
-template<class NextLayer>
-template<class ConstBufferSequence>
-std::size_t
-flat_stream<NextLayer>::
-write_some(
-    ConstBufferSequence const& buffers,
-    boost::system::error_code& ec)
-{
-    auto const result = coalesce(buffers, coalesce_limit);
-    if(result.second)
-    {
-        std::unique_ptr<char[]> p{new char[result.first]};
-        auto const b = boost::asio::buffer(p.get(), result.first);
-        boost::asio::buffer_copy(b, buffers);
-        return stream_.write_some(b, ec);
-    }
-    return stream_.write_some(
-        boost::beast::buffers_prefix(result.first, buffers), ec);
-}
-
-template<class NextLayer>
-template<
-    class MutableBufferSequence,
-    class ReadHandler>
-BOOST_ASIO_INITFN_RESULT_TYPE(
-    ReadHandler, void(boost::system::error_code, std::size_t))
-flat_stream<NextLayer>::
-async_read_some(
-    MutableBufferSequence const& buffers,
-    ReadHandler&& handler)
-{
-    static_assert(boost::beast::is_async_read_stream<next_layer_type>::value,
-        "AsyncReadStream requirements not met");
-    static_assert(boost::asio::is_mutable_buffer_sequence<
-            MutableBufferSequence >::value,
-        "MutableBufferSequence  requirements not met");
-    return stream_.async_read_some(
-        buffers, std::forward<ReadHandler>(handler));
-}
-
-template<class NextLayer>
-template<
-    class ConstBufferSequence,
-    class WriteHandler>
-BOOST_ASIO_INITFN_RESULT_TYPE(
-    WriteHandler, void(boost::system::error_code, std::size_t))
-flat_stream<NextLayer>::
-async_write_some(
-    ConstBufferSequence const& buffers,
-    WriteHandler&& handler)
-{
-    static_assert(boost::beast::is_async_write_stream<next_layer_type>::value,
-        "AsyncWriteStream requirements not met");
-    static_assert(boost::asio::is_const_buffer_sequence<
-            ConstBufferSequence>::value,
-        "ConstBufferSequence requirements not met");
-    BOOST_BEAST_HANDLER_INIT(
-        WriteHandler, void(boost::system::error_code, std::size_t));
-    write_op<ConstBufferSequence, BOOST_ASIO_HANDLER_TYPE(
-        WriteHandler, void(boost::system::error_code, std::size_t))>{
-            *this, buffers, std::move(init.completion_handler)}({}, 0);
-    return init.result.get();
-}
-
-template<class NextLayer>
-void
-teardown(
-    boost::beast::websocket::role_type role,
-    flat_stream<NextLayer>& s,
-    boost::system::error_code& ec)
-{
-    using boost::beast::websocket::teardown;
-    teardown(role, s.stream_, ec);
-}
-
-template<class NextLayer, class TeardownHandler>
-void
-async_teardown(
-    boost::beast::websocket::role_type role,
-    flat_stream<NextLayer>& s,
-    TeardownHandler&& handler)
-{
-    using boost::beast::websocket::async_teardown;
-    async_teardown(role, s.stream_, std::move(handler));
-}
-
-#endif
diff --git a/example/common/ssl_stream.hpp b/example/common/ssl_stream.hpp
deleted file mode 100644
index 1db758e1..00000000
--- a/example/common/ssl_stream.hpp
+++ /dev/null
@@ -1,329 +0,0 @@
-//
-// Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-// Official repository: https://github.com/boostorg/beast
-//
-
-#ifndef BOOST_BEAST_EXAMPLE_COMMON_SSL_STREAM_HPP
-#define BOOST_BEAST_EXAMPLE_COMMON_SSL_STREAM_HPP
-
-// This include is necessary to work with `ssl::stream` and `boost::beast::websocket::stream`
-#include <boost/beast/websocket/ssl.hpp>
-
-#include "flat_stream.hpp"
-
-#include <boost/asio/ip/tcp.hpp>
-#include <boost/asio/ssl/stream.hpp>
-#include <cstddef>
-#include <memory>
-#include <type_traits>
-#include <utility>
-
-/** C++11 enabled SSL socket wrapper
-
-    This wrapper provides an interface identical to `boost::asio::ssl::stream`,
-    with the following additional properties:
-    
-    @li Satisfies @b MoveConstructible
-    
-    @li Satisfies @b MoveAssignable
-   
-    @li Constructible from a moved socket.
-*/
-template<class NextLayer>
-class ssl_stream
-    : public boost::asio::ssl::stream_base
-{
-    using ssl_stream_type = boost::asio::ssl::stream<NextLayer>;
-    using stream_type = flat_stream<ssl_stream_type>;
-
-    std::unique_ptr<stream_type> p_;
-    boost::asio::ssl::context* ctx_;
-
-public:
-    /// The native handle type of the SSL stream.
-    using native_handle_type =
-        typename ssl_stream_type::native_handle_type;
-
-    /// Structure for use with deprecated impl_type.
-    using impl_struct = typename ssl_stream_type::impl_struct;
-
-    /// The type of the next layer.
-    using next_layer_type = typename ssl_stream_type::next_layer_type;
-
-    /// The type of the lowest layer.
-    using lowest_layer_type = typename ssl_stream_type::lowest_layer_type;
-
-    /// The type of the executor associated with the object.
-    using executor_type = typename stream_type::executor_type;
-
-    template<class Arg>
-    ssl_stream(
-        Arg&& arg,
-        boost::asio::ssl::context& ctx)
-        : p_(new stream_type{
-            std::forward<Arg>(arg), ctx})
-        , ctx_(&ctx)
-    {
-    }
-
-    ssl_stream(ssl_stream&& other)
-        : p_(std::move(other.p_))
-        , ctx_(other.ctx_)
-    {
-    }
-
-    ssl_stream& operator=(ssl_stream&& other)
-    {
-        p_ = std::move(other.p_);
-        ctx_ = other.ctx_;
-        return *this;
-    }
-
-    executor_type
-    get_executor() noexcept
-    {
-        return p_->get_executor();
-    }
-
-    native_handle_type
-    native_handle()
-    {
-        return p_->next_layer().native_handle();
-    }
-
-    next_layer_type const&
-    next_layer() const
-    {
-        return p_->next_layer().next_layer();
-    }
-
-    next_layer_type&
-    next_layer()
-    {
-        return p_->next_layer().next_layer();
-    }
-
-    lowest_layer_type&
-    lowest_layer()
-    {
-        return p_->lowest_layer();
-    }
-
-    lowest_layer_type const&
-    lowest_layer() const
-    {
-        return p_->lowest_layer();
-    }
-
-    void
-    set_verify_mode(boost::asio::ssl::verify_mode v)
-    {
-        p_->next_layer().set_verify_mode(v);
-    }
-
-    boost::system::error_code
-    set_verify_mode(boost::asio::ssl::verify_mode v,
-        boost::system::error_code& ec)
-    {
-        return p_->next_layer().set_verify_mode(v, ec);
-    }
-
-    void
-    set_verify_depth(int depth)
-    {
-        p_->next_layer().set_verify_depth(depth);
-    }
-
-    boost::system::error_code
-    set_verify_depth(
-        int depth, boost::system::error_code& ec)
-    {
-        return p_->next_layer().set_verify_depth(depth, ec);
-    }
-
-    template<class VerifyCallback>
-    void
-    set_verify_callback(VerifyCallback callback)
-    {
-        p_->next_layer().set_verify_callback(callback);
-    }
-
-    template<class VerifyCallback>
-    boost::system::error_code
-    set_verify_callback(VerifyCallback callback,
-        boost::system::error_code& ec)
-    {
-        return p_->next_layer().set_verify_callback(callback, ec);
-    }
-
-    void
-    handshake(handshake_type type)
-    {
-        p_->next_layer().handshake(type);
-    }
-
-    boost::system::error_code
-    handshake(handshake_type type,
-        boost::system::error_code& ec)
-    {
-        return p_->next_layer().handshake(type, ec);
-    }
-
-    template<class ConstBufferSequence>
-    void
-    handshake(
-        handshake_type type, ConstBufferSequence const& buffers)
-    {
-        p_->next_layer().handshake(type, buffers);
-    }
-
-    template<class ConstBufferSequence>
-    boost::system::error_code
-    handshake(handshake_type type,
-        ConstBufferSequence const& buffers,
-            boost::system::error_code& ec)
-    {
-        return p_->next_layer().handshake(type, buffers, ec);
-    }
-
-    template<class HandshakeHandler>
-    BOOST_ASIO_INITFN_RESULT_TYPE(HandshakeHandler,
-        void(boost::system::error_code))
-    async_handshake(handshake_type type,
-        BOOST_ASIO_MOVE_ARG(HandshakeHandler) handler)
-    {
-        return p_->next_layer().async_handshake(type,
-            BOOST_ASIO_MOVE_CAST(HandshakeHandler)(handler));
-    }
-
-    template<class ConstBufferSequence, class BufferedHandshakeHandler>
-    BOOST_ASIO_INITFN_RESULT_TYPE(BufferedHandshakeHandler,
-        void (boost::system::error_code, std::size_t))
-    async_handshake(handshake_type type, ConstBufferSequence const& buffers,
-        BOOST_ASIO_MOVE_ARG(BufferedHandshakeHandler) handler)
-    {
-        return p_->next_layer().async_handshake(type, buffers,
-            BOOST_ASIO_MOVE_CAST(BufferedHandshakeHandler)(handler));
-    }
-
-    void
-    shutdown()
-    {
-        p_->next_layer().shutdown();
-    }
-
-    boost::system::error_code
-    shutdown(boost::system::error_code& ec)
-    {
-        return p_->next_layer().shutdown(ec);
-    }
-
-    template<class ShutdownHandler>
-    BOOST_ASIO_INITFN_RESULT_TYPE(ShutdownHandler,
-        void (boost::system::error_code))
-    async_shutdown(BOOST_ASIO_MOVE_ARG(ShutdownHandler) handler)
-    {
-        return p_->next_layer().async_shutdown(
-            BOOST_ASIO_MOVE_CAST(ShutdownHandler)(handler));
-    }
-
-    template<class ConstBufferSequence>
-    std::size_t
-    write_some(ConstBufferSequence const& buffers)
-    {
-        return p_->write_some(buffers);
-    }
-
-    template<class ConstBufferSequence>
-    std::size_t
-    write_some(ConstBufferSequence const& buffers,
-        boost::system::error_code& ec)
-    {
-        return p_->write_some(buffers, ec);
-    }
-
-    template<class ConstBufferSequence, class WriteHandler>
-    BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
-        void (boost::system::error_code, std::size_t))
-    async_write_some(ConstBufferSequence const& buffers,
-        BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
-    {
-        return p_->async_write_some(buffers,
-            BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
-    }
-
-    template<class MutableBufferSequence>
-    std::size_t
-    read_some(MutableBufferSequence const& buffers)
-    {
-        return p_->read_some(buffers);
-    }
-
-    template<class MutableBufferSequence>
-    std::size_t
-    read_some(MutableBufferSequence const& buffers,
-        boost::system::error_code& ec)
-    {
-        return p_->read_some(buffers, ec);
-    }
-
-    template<class MutableBufferSequence, class ReadHandler>
-    BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
-        void(boost::system::error_code, std::size_t))
-    async_read_some(MutableBufferSequence const& buffers,
-        BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
-    {
-        return p_->async_read_some(buffers,
-            BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
-    }
-
-    template<class SyncStream>
-    friend
-    void
-    teardown(boost::beast::websocket::role_type,
-        ssl_stream<SyncStream>& stream,
-            boost::system::error_code& ec);
-
-    template<class AsyncStream, class TeardownHandler>
-    friend
-    void
-    async_teardown(boost::beast::websocket::role_type,
-        ssl_stream<AsyncStream>& stream, TeardownHandler&& handler);
-};
-
-// These hooks are used to inform boost::beast::websocket::stream on
-// how to tear down the connection as part of the WebSocket
-// protocol specifications
-
-template<class SyncStream>
-inline
-void
-teardown(
-    boost::beast::websocket::role_type role,
-    ssl_stream<SyncStream>& stream,
-    boost::system::error_code& ec)
-{
-    // Just forward it to the wrapped stream
-    using boost::beast::websocket::teardown;
-    teardown(role, *stream.p_, ec);
-}
-
-template<class AsyncStream, class TeardownHandler>
-inline
-void
-async_teardown(
-    boost::beast::websocket::role_type role,
-    ssl_stream<AsyncStream>& stream,
-    TeardownHandler&& handler)
-{
-    // Just forward it to the wrapped stream
-    using boost::beast::websocket::async_teardown;
-    async_teardown(role,
-        *stream.p_, std::forward<TeardownHandler>(handler));
-}
-
-#endif
diff --git a/include/boost/beast/experimental/core/detail/flat_stream.hpp b/include/boost/beast/experimental/core/detail/flat_stream.hpp
new file mode 100644
index 00000000..3a56897b
--- /dev/null
+++ b/include/boost/beast/experimental/core/detail/flat_stream.hpp
@@ -0,0 +1,64 @@
+//
+// Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Official repository: https://github.com/boostorg/beast
+//
+
+#ifndef BOOST_BEAST_CORE_DETAIL_FLAT_STREAM_HPP
+#define BOOST_BEAST_CORE_DETAIL_FLAT_STREAM_HPP
+
+#include <boost/asio/buffer.hpp>
+#include <cstdlib>
+#include <iterator>
+
+namespace boost {
+namespace beast {
+namespace detail {
+
+class flat_stream_base
+{
+public:
+    // Largest buffer size we will flatten.
+    // 16KB is the upper limit on reasonably sized HTTP messages.
+    static std::size_t constexpr coalesce_limit = 16 * 1024;
+
+    // calculates the coalesce settings for a buffer sequence
+    template<class BufferSequence>
+    static
+    std::pair<std::size_t, bool>
+    coalesce(BufferSequence const& buffers, std::size_t limit)
+    {
+        std::pair<std::size_t, bool> result{0, false};
+        auto first = boost::asio::buffer_sequence_begin(buffers);
+        auto last = boost::asio::buffer_sequence_end(buffers);
+        if(first != last)
+        {
+            result.first = boost::asio::buffer_size(*first);
+            if(result.first < limit)
+            {
+                auto it = first;
+                auto prev = first;
+                while(++it != last)
+                {
+                    auto const n =
+                        boost::asio::buffer_size(*it);
+                    if(result.first + n > limit)
+                        break;
+                    result.first += n;
+                    prev = it;
+                }
+                result.second = prev != first;
+            }
+        }
+        return result;
+    }
+};
+
+} // detail
+} // beast
+} // boost
+
+#endif
diff --git a/include/boost/beast/experimental/core/flat_stream.hpp b/include/boost/beast/experimental/core/flat_stream.hpp
new file mode 100644
index 00000000..f45275f8
--- /dev/null
+++ b/include/boost/beast/experimental/core/flat_stream.hpp
@@ -0,0 +1,353 @@
+//
+// Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Official repository: https://github.com/boostorg/beast
+//
+
+#ifndef BOOST_BEAST_CORE_FLAT_STREAM_HPP
+#define BOOST_BEAST_CORE_FLAT_STREAM_HPP
+
+#include <boost/beast/core/error.hpp>
+#include <boost/beast/core/type_traits.hpp>
+#include <boost/beast/experimental/core/detail/flat_stream.hpp>
+#include <boost/asio/async_result.hpp>
+#include <cstdlib>
+#include <utility>
+
+namespace boost {
+namespace beast {
+
+/** Stream wrapper to improve ssl::stream write performance.
+
+    This wrapper flattens writes for buffer sequences having length
+    greater than 1 and total size below a predefined amount, using
+    a dynamic memory allocation. It is primarily designed to overcome
+    a performance limitation of the current version of `boost::asio::ssl::stream`,
+    which does not use OpenSSL's scatter/gather interface for its
+    low-level read some and write some operations.
+
+    @par Example
+
+    To use the @ref flat_stream template with SSL streams, declare
+    a variable of the correct type. Parameters passed to the constructor
+    will be forwarded to the next layer's constructor:
+
+    @code
+        flat_stream<ssl::stream<ip::tcp::socket>> fs{ioc, ctx};
+    @endcode
+    Alternatively you can write
+    @code
+        ssl::stream<ip::tcp::socket> ss{ioc, ctx};
+        flat_stream<ssl::stream<ip::tcp::socket>&> fs{ss};
+    @endcode
+
+    The resulting stream may be passed to any stream algorithms which
+    operate on synchronous or asynchronous read or write streams,
+    examples include:
+    
+    @li `boost::asio::read`, `boost::asio::async_read`
+
+    @li `boost::asio::write`, `boost::asio::async_write`
+
+    @li `boost::asio::read_until`, `boost::asio::async_read_until`
+
+    The stream may also be used as a template parameter in other
+    stream wrappers, such as for websocket:
+    @code
+        websocket::stream<flat_stream<ssl::stream<ip::tcp::socket>>> ws{ioc, ctx};
+    @endcode
+
+    @tparam NextLayer The type representing the next layer, to which
+    data will be read and written during operations. For synchronous
+    operations, the type must support the @b SyncStream concept. For
+    asynchronous operations, the type must support the @b AsyncStream
+    concept. This type will usually be some variation of
+    `boost::asio::ssl::stream`.
+
+    @par Concepts
+        @b AsyncStream
+        @b SyncStream
+
+    @see
+        @li https://github.com/boostorg/beast/issues/1108
+        @li https://github.com/boostorg/asio/issues/100
+        @li https://stackoverflow.com/questions/38198638/openssl-ssl-write-from-multiple-buffers-ssl-writev
+        @li https://stackoverflow.com/questions/50026167/performance-drop-on-port-from-beast-1-0-0-b66-to-boost-1-67-0-beast
+*/
+template<class NextLayer>
+class flat_stream
+#ifndef BOOST_BEAST_DOXYGEN
+    : private detail::flat_stream_base
+#endif
+{
+    // Largest buffer size we will flatten.
+    // 16KB is the upper limit on reasonably sized HTTP messages.
+    static std::size_t constexpr max_size = 16 * 1024;
+
+    template<class, class> class write_op;
+
+    NextLayer stream_;
+
+public:
+    /// The type of the next layer.
+    using next_layer_type =
+        typename std::remove_reference<NextLayer>::type;
+
+    /// The type of the lowest layer.
+    using lowest_layer_type = boost::beast::get_lowest_layer<next_layer_type>;
+
+    /// The type of the executor associated with the object.
+    using executor_type = typename next_layer_type::executor_type;
+
+    flat_stream(flat_stream&&) = default;
+    flat_stream(flat_stream const&) = default;
+    flat_stream& operator=(flat_stream&&) = default;
+    flat_stream& operator=(flat_stream const&) = default;
+
+    /** Destructor
+
+        The treatment of pending operations will be the same as that
+        of the next layer.
+    */
+    ~flat_stream() = default;
+
+    /** Constructor
+
+        Arguments, if any, are forwarded to the next layer's constructor.
+    */
+    template<class... Args>
+    explicit
+    flat_stream(Args&&... args);
+
+    //--------------------------------------------------------------------------
+
+    /** Get the executor associated with the object.
+    
+        This function may be used to obtain the executor object that the
+        stream uses to dispatch handlers for asynchronous operations.
+
+        @return A copy of the executor that stream will use to dispatch handlers.
+    */
+    executor_type
+    get_executor() noexcept
+    {
+        return stream_.get_executor();
+    }
+
+    /** Get a reference to the next layer
+
+        This function returns a reference to the next layer
+        in a stack of stream layers.
+
+        @return A reference to the next layer in the stack of
+        stream layers.
+    */
+    next_layer_type&
+    next_layer()
+    {
+        return stream_;
+    }
+
+    /** Get a reference to the next layer
+
+        This function returns a reference to the next layer in a
+        stack of stream layers.
+
+        @return A reference to the next layer in the stack of
+        stream layers.
+    */
+    next_layer_type const&
+    next_layer() const
+    {
+        return stream_;
+    }
+
+    /** Get a reference to the lowest layer
+
+        This function returns a reference to the lowest layer
+        in a stack of stream layers.
+
+        @return A reference to the lowest layer in the stack of
+        stream layers.
+    */
+    lowest_layer_type&
+    lowest_layer()
+    {
+        return stream_.lowest_layer();
+    }
+
+    /** Get a reference to the lowest layer
+
+        This function returns a reference to the lowest layer
+        in a stack of stream layers.
+
+        @return A reference to the lowest layer in the stack of
+        stream layers. Ownership is not transferred to the caller.
+    */
+    lowest_layer_type const&
+    lowest_layer() const
+    {
+        return stream_.lowest_layer();
+    }
+
+    //--------------------------------------------------------------------------
+
+    /** Read some data from the stream.
+
+        This function is used to read data from the stream. The function call will
+        block until one or more bytes of data has been read successfully, or until
+        an error occurs.
+        
+        @param buffers The buffers into which the data will be read.
+        
+        @returns The number of bytes read.
+        
+        @throws boost::system::system_error Thrown on failure.
+        
+        @note The `read_some` operation may not read all of the requested number of
+        bytes. Consider using the function `boost::asio::read` if you need to ensure
+        that the requested amount of data is read before the blocking operation
+        completes.
+    */
+    template<class MutableBufferSequence>
+    std::size_t
+    read_some(MutableBufferSequence const& buffers);
+
+    /** Read some data from the stream.
+
+        This function is used to read data from the stream. The function call will
+        block until one or more bytes of data has been read successfully, or until
+        an error occurs.
+        
+        @param buffers The buffers into which the data will be read.
+        
+        @param ec Set to indicate what error occurred, if any.
+
+        @returns The number of bytes read.
+                
+        @note The `read_some` operation may not read all of the requested number of
+        bytes. Consider using the function `boost::asio::read` if you need to ensure
+        that the requested amount of data is read before the blocking operation
+        completes.
+    */
+    template<class MutableBufferSequence>
+    std::size_t
+    read_some(
+        MutableBufferSequence const& buffers,
+        error_code& ec);
+
+    /** Start an asynchronous read.
+    
+        This function is used to asynchronously read one or more bytes of data from
+        the stream. The function call always returns immediately.
+        
+        @param buffers The buffers into which the data will be read. Although the
+        buffers object may be copied as necessary, ownership of the underlying
+        buffers is retained by the caller, which must guarantee that they remain
+        valid until the handler is called.
+        
+        @param handler The handler to be called when the read operation completes.
+        Copies will be made of the handler as required. The equivalent function
+        signature of the handler must be:
+        @code void handler(
+          const boost::system::error_code& error, // Result of operation.
+          std::size_t bytes_transferred           // Number of bytes read.
+        ); @endcode
+        
+        @note The `read_some` operation may not read all of the requested number of
+        bytes. Consider using the function `boost::asio::async_read` if you need
+        to ensure that the requested amount of data is read before the asynchronous
+        operation completes.
+    */
+    template<
+        class MutableBufferSequence,
+        class ReadHandler>
+    BOOST_ASIO_INITFN_RESULT_TYPE(
+        ReadHandler, void(error_code, std::size_t))
+    async_read_some(
+        MutableBufferSequence const& buffers,
+        ReadHandler&& handler);
+
+    /** Write some data to the stream.
+    
+        This function is used to write data on the stream. The function call will
+        block until one or more bytes of data has been written successfully, or
+        until an error occurs.
+        
+        @param buffers The data to be written.
+        
+        @returns The number of bytes written.
+        
+        @throws boost::system::system_error Thrown on failure.
+        
+        @note The `write_some` operation may not transmit all of the data to the
+        peer. Consider using the function `boost::asio::write` if you need to
+        ensure that all data is written before the blocking operation completes.
+    */
+    template<class ConstBufferSequence>
+    std::size_t
+    write_some(ConstBufferSequence const& buffers);
+
+    /** Write some data to the stream.
+    
+        This function is used to write data on the stream. The function call will
+        block until one or more bytes of data has been written successfully, or
+        until an error occurs.
+        
+        @param buffers The data to be written.
+        
+        @param ec Set to indicate what error occurred, if any.
+
+        @returns The number of bytes written.
+                
+        @note The `write_some` operation may not transmit all of the data to the
+        peer. Consider using the function `boost::asio::write` if you need to
+        ensure that all data is written before the blocking operation completes.
+    */
+    template<class ConstBufferSequence>
+    std::size_t
+    write_some(
+        ConstBufferSequence const& buffers,
+        error_code& ec);
+
+    /** Start an asynchronous write.
+        
+        This function is used to asynchronously write one or more bytes of data to
+        the stream. The function call always returns immediately.
+        
+        @param buffers The data to be written to the stream. Although the buffers
+        object may be copied as necessary, ownership of the underlying buffers is
+        retained by the caller, which must guarantee that they remain valid until
+        the handler is called.
+        
+        @param handler The handler to be called when the write operation completes.
+        Copies will be made of the handler as required. The equivalent function
+        signature of the handler must be:
+        @code void handler(
+          const boost::system::error_code& error, // Result of operation.
+          std::size_t bytes_transferred           // Number of bytes written.
+        ); @endcode
+        
+        @note The `async_write_some` operation may not transmit all of the data to
+        the peer. Consider using the function `boost::asio::async_write` if you need
+        to ensure that all data is written before the asynchronous operation completes.
+    */
+    template<
+        class ConstBufferSequence,
+        class WriteHandler>
+    BOOST_ASIO_INITFN_RESULT_TYPE(
+        WriteHandler, void(error_code, std::size_t))
+    async_write_some(
+        ConstBufferSequence const& buffers,
+        WriteHandler&& handler);
+};
+
+} // beast
+} // boost
+
+#include <boost/beast/experimental/core/impl/flat_stream.ipp>
+
+#endif
diff --git a/include/boost/beast/experimental/core/impl/flat_stream.ipp b/include/boost/beast/experimental/core/impl/flat_stream.ipp
new file mode 100644
index 00000000..6447c43a
--- /dev/null
+++ b/include/boost/beast/experimental/core/impl/flat_stream.ipp
@@ -0,0 +1,304 @@
+//
+// Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Official repository: https://github.com/boostorg/beast
+//
+
+#ifndef BOOST_BEAST_CORE_IMPL_FLAT_STREAM_IPP
+#define BOOST_BEAST_CORE_IMPL_FLAT_STREAM_IPP
+
+#include <boost/beast/core/buffers_prefix.hpp>
+#include <boost/beast/websocket/teardown.hpp>
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
+#include <boost/asio/buffer.hpp>
+#include <boost/asio/coroutine.hpp>
+#include <boost/asio/handler_continuation_hook.hpp>
+#include <boost/asio/handler_invoke_hook.hpp>
+
+namespace boost {
+namespace beast {
+
+template<class NextLayer>
+template<class ConstBufferSequence, class Handler>
+class flat_stream<NextLayer>::write_op
+    : public boost::asio::coroutine
+{
+    using alloc_type = typename 
+        boost::asio::associated_allocator_t<Handler>::template
+            rebind<char>::other;
+
+    struct deleter
+    {
+        alloc_type alloc;
+        std::size_t size = 0;
+
+        explicit
+        deleter(alloc_type const& alloc_)
+            : alloc(alloc_)
+        {
+        }
+
+        void
+        operator()(char* p)
+        {
+            alloc.deallocate(p, size);
+        }
+    };
+
+    flat_stream<NextLayer>& s_;
+    ConstBufferSequence b_;
+    std::unique_ptr<char, deleter> p_;
+    Handler h_;
+
+public:
+    template<class DeducedHandler>
+    write_op(
+        flat_stream<NextLayer>& s,
+        ConstBufferSequence const& b,
+        DeducedHandler&& h)
+        : s_(s)
+        , b_(b)
+        , p_(nullptr, deleter{
+            (boost::asio::get_associated_allocator)(h)})
+        , h_(std::forward<DeducedHandler>(h))
+    {
+    }
+
+    using allocator_type =
+        boost::asio::associated_allocator_t<Handler>;
+
+    allocator_type
+    get_allocator() const noexcept
+    {
+        return (boost::asio::get_associated_allocator)(h_);
+    }
+
+    using executor_type = boost::asio::associated_executor_t<
+        Handler, decltype(std::declval<NextLayer&>().get_executor())>;
+
+    executor_type
+    get_executor() const noexcept
+    {
+        return (boost::asio::get_associated_executor)(
+            h_, s_.get_executor());
+    }
+
+    void
+    operator()(
+        boost::system::error_code ec,
+        std::size_t bytes_transferred);
+
+    friend
+    bool asio_handler_is_continuation(write_op* op)
+    {
+        using boost::asio::asio_handler_is_continuation;
+        return asio_handler_is_continuation(
+                std::addressof(op->h_));
+    }
+
+    template<class Function>
+    friend
+    void asio_handler_invoke(Function&& f, write_op* op)
+    {
+        using boost::asio::asio_handler_invoke;
+        asio_handler_invoke(f, std::addressof(op->h_));
+    }
+};
+
+template<class NextLayer>
+template<class ConstBufferSequence, class Handler>
+void
+flat_stream<NextLayer>::
+write_op<ConstBufferSequence, Handler>::
+operator()(
+    error_code ec,
+    std::size_t bytes_transferred)
+{
+    BOOST_ASIO_CORO_REENTER(*this)
+    {
+        BOOST_ASIO_CORO_YIELD
+        {
+            auto const result = coalesce(b_,  coalesce_limit);
+            if(result.second)
+            {
+                p_.get_deleter().size = result.first;
+                p_.reset(p_.get_deleter().alloc.allocate(
+                    p_.get_deleter().size));
+                boost::asio::buffer_copy(
+                    boost::asio::buffer(
+                        p_.get(), p_.get_deleter().size),
+                    b_, result.first);
+                s_.stream_.async_write_some(
+                    boost::asio::buffer(
+                        p_.get(), p_.get_deleter().size),
+                            std::move(*this));
+            }
+            else
+            {
+                s_.stream_.async_write_some(
+                    boost::beast::buffers_prefix(result.first, b_),
+                        std::move(*this));
+            }
+        }
+        p_.reset();
+        h_(ec, bytes_transferred);
+    }
+}
+
+//------------------------------------------------------------------------------
+
+template<class NextLayer>
+template<class... Args>
+flat_stream<NextLayer>::
+flat_stream(Args&&... args)
+    : stream_(std::forward<Args>(args)...)
+{
+}
+
+template<class NextLayer>
+template<class MutableBufferSequence>
+std::size_t
+flat_stream<NextLayer>::
+read_some(MutableBufferSequence const& buffers)
+{
+    static_assert(boost::beast::is_sync_read_stream<next_layer_type>::value,
+        "SyncReadStream requirements not met");
+    static_assert(boost::asio::is_mutable_buffer_sequence<
+        MutableBufferSequence>::value,
+            "MutableBufferSequence requirements not met");
+    error_code ec;
+    auto n = read_some(buffers, ec);
+    if(ec)
+        BOOST_THROW_EXCEPTION(boost::system::system_error{ec});
+    return n;
+}
+
+template<class NextLayer>
+template<class MutableBufferSequence>
+std::size_t
+flat_stream<NextLayer>::
+read_some(MutableBufferSequence const& buffers, error_code& ec)
+{
+    return stream_.read_some(buffers, ec);
+}
+
+template<class NextLayer>
+template<
+    class MutableBufferSequence,
+    class ReadHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(
+    ReadHandler, void(error_code, std::size_t))
+flat_stream<NextLayer>::
+async_read_some(
+    MutableBufferSequence const& buffers,
+    ReadHandler&& handler)
+{
+    static_assert(boost::beast::is_async_read_stream<next_layer_type>::value,
+        "AsyncReadStream requirements not met");
+    static_assert(boost::asio::is_mutable_buffer_sequence<
+            MutableBufferSequence >::value,
+        "MutableBufferSequence  requirements not met");
+    return stream_.async_read_some(
+        buffers, std::forward<ReadHandler>(handler));
+}
+
+template<class NextLayer>
+template<class ConstBufferSequence>
+std::size_t
+flat_stream<NextLayer>::
+write_some(ConstBufferSequence const& buffers)
+{
+    static_assert(boost::beast::is_sync_write_stream<next_layer_type>::value,
+        "SyncWriteStream requirements not met");
+    static_assert(boost::asio::is_const_buffer_sequence<
+        ConstBufferSequence>::value,
+            "ConstBufferSequence requirements not met");
+    auto const result = coalesce(buffers, coalesce_limit);
+    if(result.second)
+    {
+        std::unique_ptr<char[]> p{new char[result.first]};
+        auto const b = boost::asio::buffer(p.get(), result.first);
+        boost::asio::buffer_copy(b, buffers);
+        return stream_.write_some(b);
+    }
+    return stream_.write_some(
+        boost::beast::buffers_prefix(result.first, buffers));
+}
+
+template<class NextLayer>
+template<class ConstBufferSequence>
+std::size_t
+flat_stream<NextLayer>::
+write_some(ConstBufferSequence const& buffers, error_code& ec)
+{
+    static_assert(boost::beast::is_sync_write_stream<next_layer_type>::value,
+        "SyncWriteStream requirements not met");
+    static_assert(boost::asio::is_const_buffer_sequence<
+        ConstBufferSequence>::value,
+            "ConstBufferSequence requirements not met");
+    auto const result = coalesce(buffers, coalesce_limit);
+    if(result.second)
+    {
+        std::unique_ptr<char[]> p{new char[result.first]};
+        auto const b = boost::asio::buffer(p.get(), result.first);
+        boost::asio::buffer_copy(b, buffers);
+        return stream_.write_some(b, ec);
+    }
+    return stream_.write_some(
+        boost::beast::buffers_prefix(result.first, buffers), ec);
+}
+
+template<class NextLayer>
+template<
+    class ConstBufferSequence,
+    class WriteHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(
+    WriteHandler, void(error_code, std::size_t))
+flat_stream<NextLayer>::
+async_write_some(
+    ConstBufferSequence const& buffers,
+    WriteHandler&& handler)
+{
+    static_assert(boost::beast::is_async_write_stream<next_layer_type>::value,
+        "AsyncWriteStream requirements not met");
+    static_assert(boost::asio::is_const_buffer_sequence<
+            ConstBufferSequence>::value,
+        "ConstBufferSequence requirements not met");
+    BOOST_BEAST_HANDLER_INIT(
+        WriteHandler, void(error_code, std::size_t));
+    write_op<ConstBufferSequence, BOOST_ASIO_HANDLER_TYPE(
+        WriteHandler, void(error_code, std::size_t))>{
+            *this, buffers, std::move(init.completion_handler)}({}, 0);
+    return init.result.get();
+}
+
+template<class NextLayer>
+void
+teardown(
+    boost::beast::websocket::role_type role,
+    flat_stream<NextLayer>& s,
+    error_code& ec)
+{
+    using boost::beast::websocket::teardown;
+    teardown(role, s.next_layer(), ec);
+}
+
+template<class NextLayer, class TeardownHandler>
+void
+async_teardown(
+    boost::beast::websocket::role_type role,
+    flat_stream<NextLayer>& s,
+    TeardownHandler&& handler)
+{
+    using boost::beast::websocket::async_teardown;
+    async_teardown(role, s.next_layer(), std::move(handler));
+}
+
+} // beast
+} // boost
+
+#endif
diff --git a/test/beast/CMakeLists.txt b/test/beast/CMakeLists.txt
index f6d1f5eb..ab0de803 100644
--- a/test/beast/CMakeLists.txt
+++ b/test/beast/CMakeLists.txt
@@ -27,6 +27,7 @@ add_executable (tests-beast
 )
 
 add_subdirectory (core)
+add_subdirectory (experimental)
 add_subdirectory (http)
 add_subdirectory (websocket)
 add_subdirectory (zlib)
diff --git a/test/beast/Jamfile b/test/beast/Jamfile
index 4db6be21..7d148b9b 100644
--- a/test/beast/Jamfile
+++ b/test/beast/Jamfile
@@ -14,6 +14,7 @@ alias run-tests :
     [ compile websocket.cpp ]
     [ compile zlib.cpp ]
     core//run-tests
+    experimental//run-tests
     http//run-tests
     websocket//run-tests
     zlib//run-tests
@@ -21,6 +22,7 @@ alias run-tests :
 
 alias fat-tests :
     core//fat-tests
+    experimental//fat-tests
     http//fat-tests
     websocket//fat-tests
     zlib//fat-tests
diff --git a/test/beast/experimental/CMakeLists.txt b/test/beast/experimental/CMakeLists.txt
new file mode 100644
index 00000000..ff0765aa
--- /dev/null
+++ b/test/beast/experimental/CMakeLists.txt
@@ -0,0 +1,23 @@
+#
+# Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+#
+# Distributed under the Boost Software License, Version 1.0. (See accompanying
+# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#
+# Official repository: https://github.com/boostorg/beast
+#
+
+GroupSources(test/extras/include/boost/beast extras)
+GroupSources(subtree/unit_test/include/boost/beast extras)
+GroupSources(include/boost/beast beast)
+GroupSources(test/beast/experimental "/")
+
+add_executable (tests-beast-experimental
+    ${BOOST_BEAST_FILES}
+    ${EXTRAS_FILES}
+    ${TEST_MAIN}
+    Jamfile
+    flat_stream.cpp
+)
+
+set_property(TARGET tests-beast-experimental PROPERTY FOLDER "tests")
diff --git a/test/beast/experimental/Jamfile b/test/beast/experimental/Jamfile
new file mode 100644
index 00000000..c7ecbd7b
--- /dev/null
+++ b/test/beast/experimental/Jamfile
@@ -0,0 +1,25 @@
+#
+# Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+#
+# Distributed under the Boost Software License, Version 1.0. (See accompanying
+# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#
+# Official repository: https://github.com/boostorg/beast
+#
+
+local SOURCES =
+    flat_stream.cpp
+    ;
+
+local RUN_TESTS ;
+
+for local f in $(SOURCES)
+{
+    RUN_TESTS += [ run $(f) $(TEST_MAIN) ] ;
+}
+
+alias run-tests : $(RUN_TESTS) ;
+
+exe fat-tests : $(TEST_MAIN) $(SOURCES) ;
+
+explicit fat-tests ;
diff --git a/test/example/common/flat_stream.cpp b/test/beast/experimental/flat_stream.cpp
similarity index 95%
rename from test/example/common/flat_stream.cpp
rename to test/beast/experimental/flat_stream.cpp
index 7ef48488..977c7d54 100644
--- a/test/example/common/flat_stream.cpp
+++ b/test/beast/experimental/flat_stream.cpp
@@ -8,7 +8,7 @@
 //
 
 // Test that header file is self-contained.
-#include <example/common/flat_stream.hpp>
+#include <boost/beast/experimental/core/flat_stream.hpp>
 
 #include <boost/beast/test/websocket.hpp>
 #include <boost/beast/test/yield_to.hpp>
@@ -39,7 +39,7 @@ public:
                 for(auto const n : v0)
                     v.emplace_back("", n);
                 auto const result =
-                    ::detail::flat_stream_base::coalesce(v, limit);
+                    boost::beast::detail::flat_stream_base::coalesce(v, limit);
                 BEAST_EXPECT(result.first == count);
                 BEAST_EXPECT(result.second == copy);
                 return result;
diff --git a/test/example/common/CMakeLists.txt b/test/example/common/CMakeLists.txt
index 44e16418..f020d313 100644
--- a/test/example/common/CMakeLists.txt
+++ b/test/example/common/CMakeLists.txt
@@ -20,7 +20,6 @@ add_executable (tests-example-common
     ${TEST_MAIN}
     Jamfile
     detect_ssl.cpp
-    flat_stream.cpp
     root_certificates.cpp
     server_certificate.cpp
     session_alloc.cpp
diff --git a/test/example/common/Jamfile b/test/example/common/Jamfile
index 79ec00c0..719deba0 100644
--- a/test/example/common/Jamfile
+++ b/test/example/common/Jamfile
@@ -9,7 +9,6 @@
 
 local SOURCES =
     detect_ssl.cpp
-    flat_stream.cpp
     root_certificates.cpp
     server_certificate.cpp
     session_alloc.cpp