158 lines
3.9 KiB
C++
158 lines
3.9 KiB
C++
/*
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* Copyright 2003-2018 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef MPD_NFS_FILE_READER_HXX
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#define MPD_NFS_FILE_READER_HXX
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#include "Lease.hxx"
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#include "Callback.hxx"
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#include "event/DeferEvent.hxx"
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#include "util/Compiler.h"
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#include <string>
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#include <exception>
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#include <stdint.h>
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#include <stddef.h>
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#include <sys/stat.h>
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struct nfsfh;
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class NfsConnection;
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/**
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* A helper class which helps with reading from a file. It obtains a
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* connection lease (#NfsLease), opens the given file, "stats" the
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* file, and finally allos you to read its contents.
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*
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* To get started, derive your class from it and implement the pure
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* virtual methods, construct an instance, and call Open().
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*/
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class NfsFileReader : NfsLease, NfsCallback {
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enum class State {
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INITIAL,
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DEFER,
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MOUNT,
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OPEN,
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STAT,
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READ,
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IDLE,
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};
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State state = State::INITIAL;
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std::string server, export_name;
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const char *path;
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NfsConnection *connection;
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nfsfh *fh;
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DeferEvent defer_open;
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public:
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NfsFileReader() noexcept;
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~NfsFileReader() noexcept;
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auto &GetEventLoop() const noexcept {
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return defer_open.GetEventLoop();
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}
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void Close() noexcept;
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void DeferClose() noexcept;
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/**
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* Open the file. This method is thread-safe.
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*
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* Throws std::runtime_error on error.
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*/
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void Open(const char *uri);
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/**
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* Attempt to read from the file. This may only be done after
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* OnNfsFileOpen() has been called. Only one read operation
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* may be performed at a time.
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*
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* This method is not thread-safe and must be called from
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* within the I/O thread.
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*
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* Throws std::runtime_error on error.
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*/
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void Read(uint64_t offset, size_t size);
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/**
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* Cancel the most recent Read() call.
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*
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* This method is not thread-safe and must be called from
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* within the I/O thread.
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*/
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void CancelRead() noexcept;
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bool IsIdle() const noexcept {
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return state == State::IDLE;
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}
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protected:
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/**
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* The file has been opened successfully. It is a regular
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* file, and its size is known. It is ready to be read from
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* using Read().
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*
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* This method will be called from within the I/O thread.
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*/
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virtual void OnNfsFileOpen(uint64_t size) noexcept = 0;
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/**
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* A Read() has completed successfully.
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*
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* This method will be called from within the I/O thread.
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*/
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virtual void OnNfsFileRead(const void *data, size_t size) noexcept = 0;
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/**
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* An error has occurred, which can be either while waiting
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* for OnNfsFileOpen(), or while waiting for OnNfsFileRead(),
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* or if disconnected while idle.
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*/
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virtual void OnNfsFileError(std::exception_ptr &&e) noexcept = 0;
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private:
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/**
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* Cancel the current operation, if any. The NfsLease must be
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* unregistered already.
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*/
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void CancelOrClose() noexcept;
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void OpenCallback(nfsfh *_fh) noexcept;
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void StatCallback(const struct stat *st) noexcept;
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/* virtual methods from NfsLease */
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void OnNfsConnectionReady() noexcept final;
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void OnNfsConnectionFailed(std::exception_ptr e) noexcept final;
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void OnNfsConnectionDisconnected(std::exception_ptr e) noexcept final;
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/* virtual methods from NfsCallback */
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void OnNfsCallback(unsigned status, void *data) noexcept final;
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void OnNfsError(std::exception_ptr &&e) noexcept final;
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/* DeferEvent callback */
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void OnDeferredOpen() noexcept;
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};
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#endif
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