70 lines
1.8 KiB
C++
70 lines
1.8 KiB
C++
/*
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* Copyright (C) 2022 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <set>
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#include <fruit/fruit.h>
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#include "common/libs/fs/shared_fd.h"
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#include "common/libs/utils/result.h"
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namespace cuttlefish {
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class InstanceLockFileManager;
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enum class InUseState : char {
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kInUse = 'I',
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kNotInUse = 'N',
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};
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// Replicates tempfile.gettempdir() in Python
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std::string TempDir();
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// This class is not thread safe.
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class InstanceLockFile {
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public:
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int Instance() const;
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Result<InUseState> Status() const;
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Result<void> Status(InUseState);
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bool operator<(const InstanceLockFile&) const;
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private:
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friend class InstanceLockFileManager;
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InstanceLockFile(SharedFD fd, int instance_num);
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SharedFD fd_;
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int instance_num_;
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};
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class InstanceLockFileManager {
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public:
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INJECT(InstanceLockFileManager());
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Result<InstanceLockFile> AcquireLock(int instance_num);
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Result<std::set<InstanceLockFile>> AcquireLocks(const std::set<int>& nums);
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Result<std::optional<InstanceLockFile>> TryAcquireLock(int instance_num);
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Result<std::set<InstanceLockFile>> TryAcquireLocks(const std::set<int>& nums);
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// Best-effort attempt to find a free instance id.
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Result<std::optional<InstanceLockFile>> TryAcquireUnusedLock();
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};
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} // namespace cuttlefish
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