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75 lines
1.8 KiB
C++
75 lines
1.8 KiB
C++
// SPDX-License-Identifier: GPL-2.0-or-later
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// Copyright The Music Player Daemon Project
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#ifndef MPD_BLOCKING_NFS_CALLBACK_HXX
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#define MPD_BLOCKING_NFS_CALLBACK_HXX
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#include "Callback.hxx"
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#include "Lease.hxx"
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#include "thread/Mutex.hxx"
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#include "thread/Cond.hxx"
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#include <exception>
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class NfsConnection;
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/**
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* Utility class to implement a blocking NFS call using the libnfs
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* async API. The actual method call is deferred to the #EventLoop
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* thread, and method Run() waits for completion.
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*/
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class BlockingNfsOperation : protected NfsCallback, NfsLease {
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static constexpr std::chrono::steady_clock::duration timeout =
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std::chrono::minutes(1);
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Mutex mutex;
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Cond cond;
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bool finished;
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std::exception_ptr error;
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protected:
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NfsConnection &connection;
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public:
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BlockingNfsOperation(NfsConnection &_connection) noexcept
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:finished(false), connection(_connection) {}
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/**
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* Throws std::runtime_error on error.
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*/
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void Run();
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private:
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bool LockWaitFinished() noexcept {
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std::unique_lock lock{mutex};
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return cond.wait_for(lock, timeout, [this]{ return finished; });
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}
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/**
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* Mark the operation as "finished" and wake up the waiting
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* thread.
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*/
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void LockSetFinished() noexcept {
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const std::scoped_lock protect{mutex};
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finished = true;
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cond.notify_one();
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}
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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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protected:
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virtual void Start() = 0;
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virtual void HandleResult(unsigned status, void *data) noexcept = 0;
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};
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#endif
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