a26bf261a9
Prevents a possible bug which occurs when the caller-provided open() function throws; then the "uri" field is never set.
87 lines
2.1 KiB
C++
87 lines
2.1 KiB
C++
/*
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* Copyright 2003-2021 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_LAST_INPUT_STREAM_HXX
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#define MPD_LAST_INPUT_STREAM_HXX
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#include "Ptr.hxx"
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#include "thread/Mutex.hxx"
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#include "event/TimerEvent.hxx"
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#include <string>
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/**
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* A helper class which maintains an #InputStream that is opened once
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* and may be reused later for some time. It will be closed
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* automatically after some time.
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*
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* This class is not thread-safe. All methods must be called on the
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* thread which runs the #EventLoop.
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*/
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class LastInputStream {
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std::string uri;
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Mutex mutex;
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InputStreamPtr is;
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TimerEvent close_timer;
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public:
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explicit LastInputStream(EventLoop &event_loop) noexcept;
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~LastInputStream() noexcept;
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/**
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* Open an #InputStream instance with the given opener
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* function, but returns the cached instance if it matches.
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*
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* This object keeps owning the #InputStream; the caller shall
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* not close it.
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*/
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template<typename U, typename O>
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InputStream *Open(U &&new_uri, O &&open) {
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if (new_uri == uri) {
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if (is)
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/* refresh the timeout */
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ScheduleClose();
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return is.get();
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}
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Close();
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is = open(new_uri, mutex);
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uri = std::forward<U>(new_uri);
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if (is)
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ScheduleClose();
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return is.get();
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}
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void Close() noexcept;
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private:
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void ScheduleClose() noexcept {
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close_timer.Schedule(std::chrono::seconds(20));
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}
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void OnCloseTimer() noexcept;
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};
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#endif
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