1   
//
1   
//
2   
// Copyright (c) 2025 Vinnie Falco (vinnie dot falco at gmail dot com)
2   
// Copyright (c) 2025 Vinnie Falco (vinnie dot falco at gmail dot com)
3   
//
3   
//
4   
// Distributed under the Boost Software License, Version 1.0. (See accompanying
4   
// Distributed under the Boost Software License, Version 1.0. (See accompanying
5   
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
5   
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6   
//
6   
//
7   
// Official repository: https://github.com/cppalliance/capy
7   
// Official repository: https://github.com/cppalliance/capy
8   
//
8   
//
9  
9  
10   
#ifndef BOOST_CAPY_IO_ANY_WRITE_STREAM_HPP
10   
#ifndef BOOST_CAPY_IO_ANY_WRITE_STREAM_HPP
11   
#define BOOST_CAPY_IO_ANY_WRITE_STREAM_HPP
11   
#define BOOST_CAPY_IO_ANY_WRITE_STREAM_HPP
12  
12  
13   
#include <boost/capy/detail/config.hpp>
13   
#include <boost/capy/detail/config.hpp>
14   
#include <boost/capy/detail/await_suspend_helper.hpp>
14   
#include <boost/capy/detail/await_suspend_helper.hpp>
15   
#include <boost/capy/buffers.hpp>
15   
#include <boost/capy/buffers.hpp>
16 - 
#include <boost/capy/buffers/buffer_param.hpp>
16 + 
#include <boost/capy/buffers/buffer_array.hpp>
17   
#include <boost/capy/concept/io_awaitable.hpp>
17   
#include <boost/capy/concept/io_awaitable.hpp>
18   
#include <boost/capy/concept/write_stream.hpp>
18   
#include <boost/capy/concept/write_stream.hpp>
19   
#include <boost/capy/coro.hpp>
19   
#include <boost/capy/coro.hpp>
20   
#include <boost/capy/ex/executor_ref.hpp>
20   
#include <boost/capy/ex/executor_ref.hpp>
21   
#include <boost/capy/io_result.hpp>
21   
#include <boost/capy/io_result.hpp>
22  
22  
23   
#include <concepts>
23   
#include <concepts>
24   
#include <coroutine>
24   
#include <coroutine>
25   
#include <cstddef>
25   
#include <cstddef>
26   
#include <new>
26   
#include <new>
27   
#include <span>
27   
#include <span>
28   
#include <stop_token>
28   
#include <stop_token>
29   
#include <system_error>
29   
#include <system_error>
30   
#include <utility>
30   
#include <utility>
31  
31  
32   
namespace boost {
32   
namespace boost {
33   
namespace capy {
33   
namespace capy {
34  
34  
35   
/** Type-erased wrapper for any WriteStream.
35   
/** Type-erased wrapper for any WriteStream.
36  
36  
37   
    This class provides type erasure for any type satisfying the
37   
    This class provides type erasure for any type satisfying the
38   
    @ref WriteStream concept, enabling runtime polymorphism for
38   
    @ref WriteStream concept, enabling runtime polymorphism for
39   
    write operations. It uses cached awaitable storage to achieve
39   
    write operations. It uses cached awaitable storage to achieve
40   
    zero steady-state allocation after construction.
40   
    zero steady-state allocation after construction.
41  
41  
42   
    The wrapper supports two construction modes:
42   
    The wrapper supports two construction modes:
43   
    - **Owning**: Pass by value to transfer ownership. The wrapper
43   
    - **Owning**: Pass by value to transfer ownership. The wrapper
44   
      allocates storage and owns the stream.
44   
      allocates storage and owns the stream.
45   
    - **Reference**: Pass a pointer to wrap without ownership. The
45   
    - **Reference**: Pass a pointer to wrap without ownership. The
46   
      pointed-to stream must outlive this wrapper.
46   
      pointed-to stream must outlive this wrapper.
47  
47  
48   
    @par Awaitable Preallocation
48   
    @par Awaitable Preallocation
49   
    The constructor preallocates storage for the type-erased awaitable.
49   
    The constructor preallocates storage for the type-erased awaitable.
50   
    This reserves all virtual address space at server startup
50   
    This reserves all virtual address space at server startup
51   
    so memory usage can be measured up front, rather than
51   
    so memory usage can be measured up front, rather than
52   
    allocating piecemeal as traffic arrives.
52   
    allocating piecemeal as traffic arrives.
53  
53  
 
54 + 
    @par Immediate Completion
 
55 + 
    Operations complete immediately without suspending when the
 
56 + 
    buffer sequence is empty, or when the underlying stream's
 
57 + 
    awaitable reports readiness via `await_ready`.
 
58 +
54   
    @par Thread Safety
59   
    @par Thread Safety
55   
    Not thread-safe. Concurrent operations on the same wrapper
60   
    Not thread-safe. Concurrent operations on the same wrapper
56   
    are undefined behavior.
61   
    are undefined behavior.
57  
62  
58   
    @par Example
63   
    @par Example
59   
    @code
64   
    @code
60   
    // Owning - takes ownership of the stream
65   
    // Owning - takes ownership of the stream
61   
    any_write_stream stream(socket{ioc});
66   
    any_write_stream stream(socket{ioc});
62  
67  
63   
    // Reference - wraps without ownership
68   
    // Reference - wraps without ownership
64   
    socket sock(ioc);
69   
    socket sock(ioc);
65   
    any_write_stream stream(&sock);
70   
    any_write_stream stream(&sock);
66  
71  
67   
    const_buffer buf(data, size);
72   
    const_buffer buf(data, size);
68   
    auto [ec, n] = co_await stream.write_some(std::span(&buf, 1));
73   
    auto [ec, n] = co_await stream.write_some(std::span(&buf, 1));
69   
    @endcode
74   
    @endcode
70  
75  
71   
    @see any_read_stream, any_stream, WriteStream
76   
    @see any_read_stream, any_stream, WriteStream
72   
*/
77   
*/
73   
class any_write_stream
78   
class any_write_stream
74   
{
79   
{
75 - 
    struct awaitable_ops;
 
76   
    struct vtable;
80   
    struct vtable;
77  
81  
78   
    template<WriteStream S>
82   
    template<WriteStream S>
79   
    struct vtable_for_impl;
83   
    struct vtable_for_impl;
80  
84  
 
85 + 
    // ordered for cache line coherence
81   
    void* stream_ = nullptr;
86   
    void* stream_ = nullptr;
82   
    vtable const* vt_ = nullptr;
87   
    vtable const* vt_ = nullptr;
83   
    void* cached_awaitable_ = nullptr;
88   
    void* cached_awaitable_ = nullptr;
84   
    void* storage_ = nullptr;
89   
    void* storage_ = nullptr;
85 - 
    awaitable_ops const* active_ops_ = nullptr;
90 + 
    bool awaitable_active_ = false;
86  
91  
87   
public:
92   
public:
88   
    /** Destructor.
93   
    /** Destructor.
89  
94  
90   
        Destroys the owned stream (if any) and releases the cached
95   
        Destroys the owned stream (if any) and releases the cached
91   
        awaitable storage.
96   
        awaitable storage.
92   
    */
97   
    */
93   
    ~any_write_stream();
98   
    ~any_write_stream();
94  
99  
95   
    /** Default constructor.
100   
    /** Default constructor.
96  
101  
97   
        Constructs an empty wrapper. Operations on a default-constructed
102   
        Constructs an empty wrapper. Operations on a default-constructed
98   
        wrapper result in undefined behavior.
103   
        wrapper result in undefined behavior.
99   
    */
104   
    */
100   
    any_write_stream() = default;
105   
    any_write_stream() = default;
101  
106  
102   
    /** Non-copyable.
107   
    /** Non-copyable.
103  
108  
104   
        The awaitable cache is per-instance and cannot be shared.
109   
        The awaitable cache is per-instance and cannot be shared.
105   
    */
110   
    */
106   
    any_write_stream(any_write_stream const&) = delete;
111   
    any_write_stream(any_write_stream const&) = delete;
107   
    any_write_stream& operator=(any_write_stream const&) = delete;
112   
    any_write_stream& operator=(any_write_stream const&) = delete;
108  
113  
109   
    /** Move constructor.
114   
    /** Move constructor.
110  
115  
111   
        Transfers ownership of the wrapped stream (if owned) and
116   
        Transfers ownership of the wrapped stream (if owned) and
112   
        cached awaitable storage from `other`. After the move, `other` is
117   
        cached awaitable storage from `other`. After the move, `other` is
113   
        in a default-constructed state.
118   
        in a default-constructed state.
114  
119  
115   
        @param other The wrapper to move from.
120   
        @param other The wrapper to move from.
116   
    */
121   
    */
117   
    any_write_stream(any_write_stream&& other) noexcept
122   
    any_write_stream(any_write_stream&& other) noexcept
118   
        : stream_(std::exchange(other.stream_, nullptr))
123   
        : stream_(std::exchange(other.stream_, nullptr))
119   
        , vt_(std::exchange(other.vt_, nullptr))
124   
        , vt_(std::exchange(other.vt_, nullptr))
120   
        , cached_awaitable_(std::exchange(other.cached_awaitable_, nullptr))
125   
        , cached_awaitable_(std::exchange(other.cached_awaitable_, nullptr))
121   
        , storage_(std::exchange(other.storage_, nullptr))
126   
        , storage_(std::exchange(other.storage_, nullptr))
122 - 
        , active_ops_(std::exchange(other.active_ops_, nullptr))
127 + 
        , awaitable_active_(std::exchange(other.awaitable_active_, false))
123   
    {
128   
    {
124   
    }
129   
    }
125  
130  
126   
    /** Move assignment operator.
131   
    /** Move assignment operator.
127  
132  
128   
        Destroys any owned stream and releases existing resources,
133   
        Destroys any owned stream and releases existing resources,
129   
        then transfers ownership from `other`.
134   
        then transfers ownership from `other`.
130  
135  
131   
        @param other The wrapper to move from.
136   
        @param other The wrapper to move from.
132   
        @return Reference to this wrapper.
137   
        @return Reference to this wrapper.
133   
    */
138   
    */
134   
    any_write_stream&
139   
    any_write_stream&
135   
    operator=(any_write_stream&& other) noexcept;
140   
    operator=(any_write_stream&& other) noexcept;
136  
141  
137   
    /** Construct by taking ownership of a WriteStream.
142   
    /** Construct by taking ownership of a WriteStream.
138  
143  
139   
        Allocates storage and moves the stream into this wrapper.
144   
        Allocates storage and moves the stream into this wrapper.
140   
        The wrapper owns the stream and will destroy it.
145   
        The wrapper owns the stream and will destroy it.
141  
146  
142   
        @param s The stream to take ownership of.
147   
        @param s The stream to take ownership of.
143   
    */
148   
    */
144   
    template<WriteStream S>
149   
    template<WriteStream S>
145   
        requires (!std::same_as<std::decay_t<S>, any_write_stream>)
150   
        requires (!std::same_as<std::decay_t<S>, any_write_stream>)
146   
    any_write_stream(S s);
151   
    any_write_stream(S s);
147  
152  
148   
    /** Construct by wrapping a WriteStream without ownership.
153   
    /** Construct by wrapping a WriteStream without ownership.
149  
154  
150   
        Wraps the given stream by pointer. The stream must remain
155   
        Wraps the given stream by pointer. The stream must remain
151   
        valid for the lifetime of this wrapper.
156   
        valid for the lifetime of this wrapper.
152  
157  
153   
        @param s Pointer to the stream to wrap.
158   
        @param s Pointer to the stream to wrap.
154   
    */
159   
    */
155   
    template<WriteStream S>
160   
    template<WriteStream S>
156   
    any_write_stream(S* s);
161   
    any_write_stream(S* s);
157  
162  
158   
    /** Check if the wrapper contains a valid stream.
163   
    /** Check if the wrapper contains a valid stream.
159  
164  
160   
        @return `true` if wrapping a stream, `false` if default-constructed
165   
        @return `true` if wrapping a stream, `false` if default-constructed
161   
            or moved-from.
166   
            or moved-from.
162   
    */
167   
    */
163   
    bool
168   
    bool
164   
    has_value() const noexcept
169   
    has_value() const noexcept
165   
    {
170   
    {
166   
        return stream_ != nullptr;
171   
        return stream_ != nullptr;
167   
    }
172   
    }
168  
173  
169   
    /** Check if the wrapper contains a valid stream.
174   
    /** Check if the wrapper contains a valid stream.
170  
175  
171   
        @return `true` if wrapping a stream, `false` if default-constructed
176   
        @return `true` if wrapping a stream, `false` if default-constructed
172   
            or moved-from.
177   
            or moved-from.
173   
    */
178   
    */
174   
    explicit
179   
    explicit
175   
    operator bool() const noexcept
180   
    operator bool() const noexcept
176   
    {
181   
    {
177   
        return has_value();
182   
        return has_value();
178   
    }
183   
    }
179  
184  
180   
    /** Initiate an asynchronous write operation.
185   
    /** Initiate an asynchronous write operation.
181  
186  
182   
        Writes data from the provided buffer sequence. The operation
187   
        Writes data from the provided buffer sequence. The operation
183   
        completes when at least one byte has been written, or an error
188   
        completes when at least one byte has been written, or an error
184   
        occurs.
189   
        occurs.
185  
190  
186   
        @param buffers The buffer sequence containing data to write.
191   
        @param buffers The buffer sequence containing data to write.
187   
            Passed by value to ensure the sequence lives in the
192   
            Passed by value to ensure the sequence lives in the
188   
            coroutine frame across suspension points.
193   
            coroutine frame across suspension points.
189  
194  
190   
        @return An awaitable yielding `(error_code,std::size_t)`.
195   
        @return An awaitable yielding `(error_code,std::size_t)`.
191  
196  
 
197 + 
        @par Immediate Completion
 
198 + 
        The operation completes immediately without suspending
 
199 + 
        the calling coroutine when:
 
200 + 
        @li The buffer sequence is empty, returning `{error_code{}, 0}`.
 
201 + 
        @li The underlying stream's awaitable reports immediate
 
202 + 
            readiness via `await_ready`.
 
203 +
 
204 + 
        @note This is a partial operation and may not process the
 
205 + 
        entire buffer sequence. Use the composed @ref write algorithm
 
206 + 
        for guaranteed complete transfer.
 
207 +
192   
        @par Preconditions
208   
        @par Preconditions
193   
        The wrapper must contain a valid stream (`has_value() == true`).
209   
        The wrapper must contain a valid stream (`has_value() == true`).
194   
    */
210   
    */
195   
    template<ConstBufferSequence CB>
211   
    template<ConstBufferSequence CB>
196   
    auto
212   
    auto
197   
    write_some(CB buffers);
213   
    write_some(CB buffers);
198  
214  
199   
protected:
215   
protected:
200   
    /** Rebind to a new stream after move.
216   
    /** Rebind to a new stream after move.
201  
217  
202   
        Updates the internal pointer to reference a new stream object.
218   
        Updates the internal pointer to reference a new stream object.
203   
        Used by owning wrappers after move assignment when the owned
219   
        Used by owning wrappers after move assignment when the owned
204   
        object has moved to a new location.
220   
        object has moved to a new location.
205  
221  
206   
        @param new_stream The new stream to bind to. Must be the same
222   
        @param new_stream The new stream to bind to. Must be the same
207   
            type as the original stream.
223   
            type as the original stream.
208  
224  
209   
        @note Terminates if called with a stream of different type
225   
        @note Terminates if called with a stream of different type
210   
            than the original.
226   
            than the original.
211   
    */
227   
    */
212   
    template<WriteStream S>
228   
    template<WriteStream S>
213   
    void
229   
    void
214   
    rebind(S& new_stream) noexcept
230   
    rebind(S& new_stream) noexcept
215   
    {
231   
    {
216   
        if(vt_ != &vtable_for_impl<S>::value)
232   
        if(vt_ != &vtable_for_impl<S>::value)
217   
            std::terminate();
233   
            std::terminate();
218   
        stream_ = &new_stream;
234   
        stream_ = &new_stream;
219   
    }
235   
    }
220   
};
236   
};
221  
237  
222   
//----------------------------------------------------------
238   
//----------------------------------------------------------
223  
239  
224 - 
struct any_write_stream::awaitable_ops
240 + 
struct any_write_stream::vtable
225   
{
241   
{
 
242 + 
    // ordered by call frequency for cache line coherence
 
243 + 
    void (*construct_awaitable)(
 
244 + 
        void* stream,
 
245 + 
        void* storage,
 
246 + 
        std::span<const_buffer const> buffers);
226   
    bool (*await_ready)(void*);
247   
    bool (*await_ready)(void*);
227   
    coro (*await_suspend)(void*, coro, executor_ref, std::stop_token);
248   
    coro (*await_suspend)(void*, coro, executor_ref, std::stop_token);
228   
    io_result<std::size_t> (*await_resume)(void*);
249   
    io_result<std::size_t> (*await_resume)(void*);
229 - 
    void (*destroy)(void*) noexcept;
250 + 
    void (*destroy_awaitable)(void*) noexcept;
230 - 
};
 
231 -
 
232 - 
struct any_write_stream::vtable
 
233 - 
{
 
234 - 
    void (*destroy)(void*) noexcept;
 
235   
    std::size_t awaitable_size;
251   
    std::size_t awaitable_size;
236   
    std::size_t awaitable_align;
252   
    std::size_t awaitable_align;
237 - 
    awaitable_ops const* (*construct_awaitable)(
253 + 
    void (*destroy)(void*) noexcept;
238 - 
        void* stream,
 
239 - 
        void* storage,
 
240 - 
        std::span<const_buffer const> buffers);
 
241   
};
254   
};
242  
255  
243   
template<WriteStream S>
256   
template<WriteStream S>
244   
struct any_write_stream::vtable_for_impl
257   
struct any_write_stream::vtable_for_impl
245   
{
258   
{
246   
    using Awaitable = decltype(std::declval<S&>().write_some(
259   
    using Awaitable = decltype(std::declval<S&>().write_some(
247   
        std::span<const_buffer const>{}));
260   
        std::span<const_buffer const>{}));
248  
261  
249   
    static void
262   
    static void
250   
    do_destroy_impl(void* stream) noexcept
263   
    do_destroy_impl(void* stream) noexcept
251   
    {
264   
    {
252   
        static_cast<S*>(stream)->~S();
265   
        static_cast<S*>(stream)->~S();
253   
    }
266   
    }
254  
267  
255 - 
    static awaitable_ops const*
268 + 
    static void
256   
    construct_awaitable_impl(
269   
    construct_awaitable_impl(
257   
        void* stream,
270   
        void* stream,
258   
        void* storage,
271   
        void* storage,
259   
        std::span<const_buffer const> buffers)
272   
        std::span<const_buffer const> buffers)
260   
    {
273   
    {
261   
        auto& s = *static_cast<S*>(stream);
274   
        auto& s = *static_cast<S*>(stream);
262 -
 
263 - 
        static constexpr awaitable_ops ops = {
 
264 - 
            +[](void* p) {
 
265 - 
                return static_cast<Awaitable*>(p)->await_ready();
 
266 - 
            },
 
267 - 
            +[](void* p, coro h, executor_ref ex, std::stop_token token) {
 
268 - 
                return detail::call_await_suspend(
 
269 - 
                    static_cast<Awaitable*>(p), h, ex, token);
 
270 - 
            },
 
271 - 
            +[](void* p) {
 
272 - 
                return static_cast<Awaitable*>(p)->await_resume();
 
273 - 
            },
 
274 - 
            +[](void* p) noexcept {
 
275 - 
                static_cast<Awaitable*>(p)->~Awaitable();
 
276 - 
            }
 
277 - 
        };
 
278 - 
        return &ops;
 
279   
        ::new(storage) Awaitable(s.write_some(buffers));
275   
        ::new(storage) Awaitable(s.write_some(buffers));
280   
    }
276   
    }
281  
277  
282   
    static constexpr vtable value = {
278   
    static constexpr vtable value = {
283 - 
        &do_destroy_impl,
279 + 
        &construct_awaitable_impl,
 
280 + 
        +[](void* p) {
 
281 + 
            return static_cast<Awaitable*>(p)->await_ready();
 
282 + 
        },
 
283 + 
        +[](void* p, coro h, executor_ref ex, std::stop_token token) {
 
284 + 
            return detail::call_await_suspend(
 
285 + 
                static_cast<Awaitable*>(p), h, ex, token);
 
286 + 
        },
 
287 + 
        +[](void* p) {
 
288 + 
            return static_cast<Awaitable*>(p)->await_resume();
 
289 + 
        },
 
290 + 
        +[](void* p) noexcept {
 
291 + 
            static_cast<Awaitable*>(p)->~Awaitable();
 
292 + 
        },
284   
        sizeof(Awaitable),
293   
        sizeof(Awaitable),
285   
        alignof(Awaitable),
294   
        alignof(Awaitable),
286 - 
        &construct_awaitable_impl
295 + 
        &do_destroy_impl
287   
    };
296   
    };
288   
};
297   
};
289  
298  
290   
//----------------------------------------------------------
299   
//----------------------------------------------------------
291  
300  
292   
inline
301   
inline
293   
any_write_stream::~any_write_stream()
302   
any_write_stream::~any_write_stream()
294   
{
303   
{
295   
    if(storage_)
304   
    if(storage_)
296   
    {
305   
    {
297   
        vt_->destroy(stream_);
306   
        vt_->destroy(stream_);
298   
        ::operator delete(storage_);
307   
        ::operator delete(storage_);
299   
    }
308   
    }
300   
    if(cached_awaitable_)
309   
    if(cached_awaitable_)
301   
    {
310   
    {
302 - 
        if(active_ops_)
311 + 
        if(awaitable_active_)
303 - 
            active_ops_->destroy(cached_awaitable_);
312 + 
            vt_->destroy_awaitable(cached_awaitable_);
304   
        ::operator delete(cached_awaitable_);
313   
        ::operator delete(cached_awaitable_);
305   
    }
314   
    }
306   
}
315   
}
307  
316  
308   
inline any_write_stream&
317   
inline any_write_stream&
309   
any_write_stream::operator=(any_write_stream&& other) noexcept
318   
any_write_stream::operator=(any_write_stream&& other) noexcept
310   
{
319   
{
311   
    if(this != &other)
320   
    if(this != &other)
312   
    {
321   
    {
313   
        if(storage_)
322   
        if(storage_)
314   
        {
323   
        {
315   
            vt_->destroy(stream_);
324   
            vt_->destroy(stream_);
316   
            ::operator delete(storage_);
325   
            ::operator delete(storage_);
317   
        }
326   
        }
318   
        if(cached_awaitable_)
327   
        if(cached_awaitable_)
319   
        {
328   
        {
320 - 
            if(active_ops_)
329 + 
            if(awaitable_active_)
321 - 
                active_ops_->destroy(cached_awaitable_);
330 + 
                vt_->destroy_awaitable(cached_awaitable_);
322   
            ::operator delete(cached_awaitable_);
331   
            ::operator delete(cached_awaitable_);
323   
        }
332   
        }
324   
        stream_ = std::exchange(other.stream_, nullptr);
333   
        stream_ = std::exchange(other.stream_, nullptr);
325   
        vt_ = std::exchange(other.vt_, nullptr);
334   
        vt_ = std::exchange(other.vt_, nullptr);
326   
        cached_awaitable_ = std::exchange(other.cached_awaitable_, nullptr);
335   
        cached_awaitable_ = std::exchange(other.cached_awaitable_, nullptr);
327   
        storage_ = std::exchange(other.storage_, nullptr);
336   
        storage_ = std::exchange(other.storage_, nullptr);
328 - 
        active_ops_ = std::exchange(other.active_ops_, nullptr);
337 + 
        awaitable_active_ = std::exchange(other.awaitable_active_, false);
329   
    }
338   
    }
330   
    return *this;
339   
    return *this;
331   
}
340   
}
332  
341  
333   
template<WriteStream S>
342   
template<WriteStream S>
334   
    requires (!std::same_as<std::decay_t<S>, any_write_stream>)
343   
    requires (!std::same_as<std::decay_t<S>, any_write_stream>)
335   
any_write_stream::any_write_stream(S s)
344   
any_write_stream::any_write_stream(S s)
336   
    : vt_(&vtable_for_impl<S>::value)
345   
    : vt_(&vtable_for_impl<S>::value)
337   
{
346   
{
338   
    struct guard {
347   
    struct guard {
339   
        any_write_stream* self;
348   
        any_write_stream* self;
340   
        bool committed = false;
349   
        bool committed = false;
341   
        ~guard() {
350   
        ~guard() {
342   
            if(!committed && self->storage_) {
351   
            if(!committed && self->storage_) {
343   
                self->vt_->destroy(self->stream_);
352   
                self->vt_->destroy(self->stream_);
344   
                ::operator delete(self->storage_);
353   
                ::operator delete(self->storage_);
345   
                self->storage_ = nullptr;
354   
                self->storage_ = nullptr;
346   
                self->stream_ = nullptr;
355   
                self->stream_ = nullptr;
347   
            }
356   
            }
348   
        }
357   
        }
349   
    } g{this};
358   
    } g{this};
350  
359  
351   
    storage_ = ::operator new(sizeof(S));
360   
    storage_ = ::operator new(sizeof(S));
352   
    stream_ = ::new(storage_) S(std::move(s));
361   
    stream_ = ::new(storage_) S(std::move(s));
353  
362  
354   
    // Preallocate the awaitable storage
363   
    // Preallocate the awaitable storage
355   
    cached_awaitable_ = ::operator new(vt_->awaitable_size);
364   
    cached_awaitable_ = ::operator new(vt_->awaitable_size);
356  
365  
357   
    g.committed = true;
366   
    g.committed = true;
358   
}
367   
}
359  
368  
360   
template<WriteStream S>
369   
template<WriteStream S>
361   
any_write_stream::any_write_stream(S* s)
370   
any_write_stream::any_write_stream(S* s)
362   
    : stream_(s)
371   
    : stream_(s)
363   
    , vt_(&vtable_for_impl<S>::value)
372   
    , vt_(&vtable_for_impl<S>::value)
364   
{
373   
{
365   
    // Preallocate the awaitable storage
374   
    // Preallocate the awaitable storage
366   
    cached_awaitable_ = ::operator new(vt_->awaitable_size);
375   
    cached_awaitable_ = ::operator new(vt_->awaitable_size);
367   
}
376   
}
368  
377  
369   
//----------------------------------------------------------
378   
//----------------------------------------------------------
370  
379  
371   
template<ConstBufferSequence CB>
380   
template<ConstBufferSequence CB>
372   
auto
381   
auto
373   
any_write_stream::write_some(CB buffers)
382   
any_write_stream::write_some(CB buffers)
374   
{
383   
{
375   
    struct awaitable
384   
    struct awaitable
376   
    {
385   
    {
377   
        any_write_stream* self_;
386   
        any_write_stream* self_;
378 - 
        const_buffer_param<CB> bp_;
387 + 
        const_buffer_array<detail::max_iovec_> ba_;
 
388 +
 
389 + 
        awaitable(
 
390 + 
            any_write_stream* self,
 
391 + 
            CB const& buffers) noexcept
 
392 + 
            : self_(self)
 
393 + 
            , ba_(buffers)
 
394 + 
        {
 
395 + 
        }
379  
396  
380   
        bool
397   
        bool
381   
        await_ready() const noexcept
398   
        await_ready() const noexcept
382   
        {
399   
        {
383 - 
            return false;
400 + 
            return ba_.to_span().empty();
384   
        }
401   
        }
385  
402  
386   
        coro
403   
        coro
387   
        await_suspend(coro h, executor_ref ex, std::stop_token token)
404   
        await_suspend(coro h, executor_ref ex, std::stop_token token)
388   
        {
405   
        {
389 - 
            // Construct the underlying awaitable into cached storage
406 + 
            self_->vt_->construct_awaitable(
390 - 
            self_->active_ops_ = self_->vt_->construct_awaitable(
 
391   
                self_->stream_,
407   
                self_->stream_,
392   
                self_->cached_awaitable_,
408   
                self_->cached_awaitable_,
393 - 
                bp_.data());
409 + 
                ba_.to_span());
 
410 + 
            self_->awaitable_active_ = true;
394  
411  
395 - 
            // Check if underlying is immediately ready
412 + 
            if(self_->vt_->await_ready(self_->cached_awaitable_))
396 - 
            if(self_->active_ops_->await_ready(self_->cached_awaitable_))
 
397   
                return h;
413   
                return h;
398  
414  
399 - 
            // Forward to underlying awaitable
415 + 
            return self_->vt_->await_suspend(
400 - 
            return self_->active_ops_->await_suspend(
 
401   
                self_->cached_awaitable_, h, ex, token);
416   
                self_->cached_awaitable_, h, ex, token);
402   
        }
417   
        }
403  
418  
404   
        io_result<std::size_t>
419   
        io_result<std::size_t>
405   
        await_resume()
420   
        await_resume()
406   
        {
421   
        {
 
422 + 
            if(!self_->awaitable_active_)
 
423 + 
                return {{}, 0};
407   
            struct guard {
424   
            struct guard {
408   
                any_write_stream* self;
425   
                any_write_stream* self;
409   
                ~guard() {
426   
                ~guard() {
410 - 
                    self->active_ops_->destroy(self->cached_awaitable_);
427 + 
                    self->vt_->destroy_awaitable(self->cached_awaitable_);
411 - 
                    self->active_ops_ = nullptr;
428 + 
                    self->awaitable_active_ = false;
412   
                }
429   
                }
413   
            } g{self_};
430   
            } g{self_};
414 - 
            return self_->active_ops_->await_resume(
431 + 
            return self_->vt_->await_resume(
415   
                self_->cached_awaitable_);
432   
                self_->cached_awaitable_);
416   
        }
433   
        }
417   
    };
434   
    };
418 - 
    return awaitable{this, const_buffer_param<CB>(buffers)};
435 + 
    return awaitable{this, buffers};
419   
}
436   
}
420  
437  
421   
} // namespace capy
438   
} // namespace capy
422   
} // namespace boost
439   
} // namespace boost
423  
440  
424   
#endif
441   
#endif