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// Copyright 2014 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef EXPERIMENTAL_USERS_GCONNELL_AFPACKET_AIO_H_
#define EXPERIMENTAL_USERS_GCONNELL_AFPACKET_AIO_H_
#include <stddef.h>
#include <libaio.h>
#include <set>
#include <string>
#include "packets.h"
#include "util.h"
namespace st {
namespace io {
class SingleFile; // Internal class, used by Output.
} // namespace io
// Output implements an asynchronous, single-threaded method of writing
// contiguous data to a file. At any given time, Output will maintain an
// ordered circular queue of asynchronous IO operations which it has submitted
// to the kernel. PWrite requests will create a new such IO operation and
// submit it, flushing whatever operation it replaces, then returning.
// File closing also happens asynchronously. A request to close a file does not
// immediately close it. Instead, it schedules the close to happen after the
// last PWrite to that file finishes.
class Output {
public:
// Create a new async IO queue with aiops slots for IO operations.
// This class originally starts out with no file... an Open call must occur
// before any PWrites to open a file.
explicit Output(int aiops);
// Flush all files on exit.
virtual ~Output();
// Open a new file. Will fail if a file is already open.
// If initial_size > 0, will attempt to preallocate the file to be
// that many bytes.
Error Rotate(const std::string& dirname, int64_t micros,
int64_t initial_size);
// Close and flush all files.
Error Flush();
// Write the given Block out to the given offset in the current file,
// asynchronously. This call takes ownership of the underlying block (via a
// b->Swap()), so you're free to discard your local block after this call.
// The block will be freed once its IO operation has completed.
Error Write(Block* b);
// Check to see if any outstanding IO operations can be marked as completed
// and their blocks returned to the kernel. If 'block' is set, blocks until
// at least one operation has been completed.
Error CheckForCompletedOps(bool block);
private:
Error SetUp();
int Outstanding();
Error MaybeCloseFile(io::SingleFile* file);
io_context_t ctx_;
int max_ops_;
io::SingleFile* current_;
std::set<io::SingleFile*> files_;
DISALLOW_COPY_AND_ASSIGN(Output);
};
} // namespace st
#endif // EXPERIMENTAL_USERS_GCONNELL_AFPACKET_AIO_H_
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