85 lines
2.4 KiB
C
85 lines
2.4 KiB
C
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/*
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* Copyright (c) 2011 by Michael Berlin, Zuse Institute Berlin
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*
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* Licensed under the BSD License, see LICENSE file for details.
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*
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*/
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#ifndef CPP_INCLUDE_LIBXTREEMFS_UUID_ITERATOR_H_
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#define CPP_INCLUDE_LIBXTREEMFS_UUID_ITERATOR_H_
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#include <boost/thread/mutex.hpp>
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#include <gtest/gtest_prod.h>
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#include <list>
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#include <string>
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#include "libxtreemfs/uuid_item.h"
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#include "libxtreemfs/uuid_container.h"
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namespace xtreemfs {
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/** Stores a list of all UUIDs of a replicated service and allows to iterate
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* through them.
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*
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* If an UUID was marked as failed and this is the current UUID, the next
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* call of GetUUID() will return another available, not as failed marked,
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* UUID.
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*
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* If the last UUID in the list is marked as failed, the status of all entries
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* will be reset and the current UUID is set to the first in the list.
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*
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* Additionally, it is allowed to set the current UUID to a specific one,
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* regardless of its current state. This is needed in case a service did
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* redirect a request to another UUID.
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*/
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class UUIDIterator {
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public:
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UUIDIterator();
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virtual ~UUIDIterator();
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/** Get the current UUID (by default the first in the list).
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*
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* @throws UUIDIteratorListIsEmpyException
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*/
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virtual void GetUUID(std::string* result);
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/** Marks "uuid" as failed. Use this function to advance to the next in the
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* list. */
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virtual void MarkUUIDAsFailed(const std::string& uuid);
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/** Sets "uuid" as current UUID. If uuid was not found in the list of UUIDs,
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* it will be added to the UUIDIterator. */
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virtual void SetCurrentUUID(const std::string& uuid) = 0;
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/** Clear the list. */
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virtual void Clear() = 0;
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/** Returns the list of UUIDs and their status. */
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virtual std::string DebugString();
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protected:
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/** Obtain a lock on this when accessing uuids_ or current_uuid_. */
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boost::mutex mutex_;
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/** Current UUID (advanced if entries are marked as failed).
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*
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* Please note: "Lists have the important property that insertion and splicing
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* do not invalidate iterators to list elements [...]"
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* (http://www.sgi.com/tech/stl/List.html)
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*/
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std::list<UUIDItem*>::iterator current_uuid_;
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/** List of UUIDs. */
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std::list<UUIDItem*> uuids_;
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template<typename T>
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FRIEND_TEST(UUIDIteratorTest, ResetAfterEndOfList);
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template<typename T>
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FRIEND_TEST(UUIDIteratorTest, SetCurrentUUID);
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};
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} // namespace xtreemfs
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#endif // CPP_INCLUDE_LIBXTREEMFS_UUID_ITERATOR_H_
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