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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
* Ceph - scalable distributed file system
*
* Copyright (C) 2017 Red Hat, Inc.
*
* This is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 2.1, as published by the Free Software
* Foundation. See file COPYING.
*/
#ifndef LIBRADOS_ASIO_H
#define LIBRADOS_ASIO_H
#include "include/rados/librados.hpp"
#include "common/async/completion.h"
/// Defines asynchronous librados operations that satisfy all of the
/// "Requirements on asynchronous operations" imposed by the C++ Networking TS
/// in section 13.2.7. Many of the type and variable names below are taken
/// directly from those requirements.
///
/// The current draft of the Networking TS (as of 2017-11-27) is available here:
/// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/n4711.pdf
///
/// The boost::asio documentation duplicates these requirements here:
/// http://www.boost.org/doc/libs/1_66_0/doc/html/boost_asio/reference/asynchronous_operations.html
namespace librados {
namespace detail {
/// unique_ptr with custom deleter for AioCompletion
struct AioCompletionDeleter {
void operator()(AioCompletion *c) { c->release(); }
};
using unique_aio_completion_ptr =
std::unique_ptr<AioCompletion, AioCompletionDeleter>;
/// Invokes the given completion handler. When the type of Result is not void,
/// storage is provided for it and that result is passed as an additional
/// argument to the handler.
template <typename Result>
struct Invoker {
using Signature = void(boost::system::error_code, Result);
Result result;
template <typename Completion>
void dispatch(Completion&& completion, boost::system::error_code ec) {
ceph::async::dispatch(std::move(completion), ec, std::move(result));
}
};
// specialization for Result=void
template <>
struct Invoker<void> {
using Signature = void(boost::system::error_code);
template <typename Completion>
void dispatch(Completion&& completion, boost::system::error_code ec) {
ceph::async::dispatch(std::move(completion), ec);
}
};
template <typename Result>
struct AsyncOp : Invoker<Result> {
unique_aio_completion_ptr aio_completion;
using Signature = typename Invoker<Result>::Signature;
using Completion = ceph::async::Completion<Signature, AsyncOp<Result>>;
static void aio_dispatch(completion_t cb, void *arg) {
// reclaim ownership of the completion
auto p = std::unique_ptr<Completion>{static_cast<Completion*>(arg)};
// move result out of Completion memory being freed
auto op = std::move(p->user_data);
const int ret = op.aio_completion->get_return_value();
boost::system::error_code ec;
if (ret < 0) {
ec.assign(-ret, boost::system::system_category());
}
op.dispatch(std::move(p), ec);
}
template <typename Executor1, typename CompletionHandler>
static auto create(const Executor1& ex1, CompletionHandler&& handler) {
auto p = Completion::create(ex1, std::move(handler));
p->user_data.aio_completion.reset(
Rados::aio_create_completion(p.get(), nullptr, aio_dispatch));
return p;
}
};
} // namespace detail
/// Calls IoCtx::aio_read() and arranges for the AioCompletion to call a
/// given handler with signature (boost::system::error_code, bufferlist).
template <typename ExecutionContext, typename CompletionToken>
auto async_read(ExecutionContext& ctx, IoCtx& io, const std::string& oid,
size_t len, uint64_t off, CompletionToken&& token)
{
using Op = detail::AsyncOp<bufferlist>;
using Signature = typename Op::Signature;
boost::asio::async_completion<CompletionToken, Signature> init(token);
auto p = Op::create(ctx.get_executor(), init.completion_handler);
auto& op = p->user_data;
int ret = io.aio_read(oid, op.aio_completion.get(), &op.result, len, off);
if (ret < 0) {
auto ec = boost::system::error_code{-ret, boost::system::system_category()};
ceph::async::post(std::move(p), ec, bufferlist{});
} else {
p.release(); // release ownership until completion
}
return init.result.get();
}
/// Calls IoCtx::aio_write() and arranges for the AioCompletion to call a
/// given handler with signature (boost::system::error_code).
template <typename ExecutionContext, typename CompletionToken>
auto async_write(ExecutionContext& ctx, IoCtx& io, const std::string& oid,
bufferlist &bl, size_t len, uint64_t off,
CompletionToken&& token)
{
using Op = detail::AsyncOp<void>;
using Signature = typename Op::Signature;
boost::asio::async_completion<CompletionToken, Signature> init(token);
auto p = Op::create(ctx.get_executor(), init.completion_handler);
auto& op = p->user_data;
int ret = io.aio_write(oid, op.aio_completion.get(), bl, len, off);
if (ret < 0) {
auto ec = boost::system::error_code{-ret, boost::system::system_category()};
ceph::async::post(std::move(p), ec);
} else {
p.release(); // release ownership until completion
}
return init.result.get();
}
/// Calls IoCtx::aio_operate() and arranges for the AioCompletion to call a
/// given handler with signature (boost::system::error_code, bufferlist).
template <typename ExecutionContext, typename CompletionToken>
auto async_operate(ExecutionContext& ctx, IoCtx& io, const std::string& oid,
ObjectReadOperation *read_op, int flags,
CompletionToken&& token)
{
using Op = detail::AsyncOp<bufferlist>;
using Signature = typename Op::Signature;
boost::asio::async_completion<CompletionToken, Signature> init(token);
auto p = Op::create(ctx.get_executor(), init.completion_handler);
auto& op = p->user_data;
int ret = io.aio_operate(oid, op.aio_completion.get(), read_op,
flags, &op.result);
if (ret < 0) {
auto ec = boost::system::error_code{-ret, boost::system::system_category()};
ceph::async::post(std::move(p), ec, bufferlist{});
} else {
p.release(); // release ownership until completion
}
return init.result.get();
}
/// Calls IoCtx::aio_operate() and arranges for the AioCompletion to call a
/// given handler with signature (boost::system::error_code).
template <typename ExecutionContext, typename CompletionToken>
auto async_operate(ExecutionContext& ctx, IoCtx& io, const std::string& oid,
ObjectWriteOperation *write_op, int flags,
CompletionToken &&token)
{
using Op = detail::AsyncOp<void>;
using Signature = typename Op::Signature;
boost::asio::async_completion<CompletionToken, Signature> init(token);
auto p = Op::create(ctx.get_executor(), init.completion_handler);
auto& op = p->user_data;
int ret = io.aio_operate(oid, op.aio_completion.get(), write_op, flags);
if (ret < 0) {
auto ec = boost::system::error_code{-ret, boost::system::system_category()};
ceph::async::post(std::move(p), ec);
} else {
p.release(); // release ownership until completion
}
return init.result.get();
}
} // namespace librados
#endif // LIBRADOS_ASIO_H
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