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e6ab9d58a2
Summary: While destroying JournalDelta entries, unzip the chain as we go and destroy each entry one by one. This prevents the stack from overflowing on long JournalDelta chains and should fix some flaky tests. Reviewed By: wez Differential Revision: D9355365 fbshipit-source-id: 31af124d318ca5d7a84314b707e1b3c71b2ccaa9
129 lines
4.1 KiB
C++
129 lines
4.1 KiB
C++
/*
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* Copyright (c) 2016-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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*/
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#pragma once
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#include <chrono>
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#include <unordered_set>
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#include "eden/fs/journal/JournalDeltaPtr.h"
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#include "eden/fs/model/Hash.h"
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#include "eden/fs/utils/PathFuncs.h"
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namespace facebook {
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namespace eden {
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struct PathChangeInfo {
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PathChangeInfo() : existedBefore{false}, existedAfter{false} {}
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PathChangeInfo(bool before, bool after)
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: existedBefore{before}, existedAfter{after} {}
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bool isNew() const {
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return !existedBefore && existedAfter;
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}
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/// Whether this path existed at the start of this delta.
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bool existedBefore : 1;
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/**
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* Whether this path existed at the end of this delta.
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* If existedAfter && !existedBefore, then the file can be considered new in
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* this delta.
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*/
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bool existedAfter : 1;
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// TODO: It may make sense to maintain an existenceChanged bit to distinguish
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// between a file being changed and it being removed and added in the same
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// delta.
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};
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class JournalDelta {
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public:
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using SequenceNumber = uint64_t;
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enum Created { CREATED };
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enum Removed { REMOVED };
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enum Changed { CHANGED };
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enum Renamed { RENAME };
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enum Replaced { REPLACE };
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JournalDelta() = default;
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JournalDelta(JournalDelta&&) = default;
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JournalDelta& operator=(JournalDelta&&) = default;
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JournalDelta(const JournalDelta&) = delete;
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JournalDelta& operator=(const JournalDelta&) = delete;
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JournalDelta(RelativePathPiece fileName, Created);
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JournalDelta(RelativePathPiece fileName, Removed);
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JournalDelta(RelativePathPiece fileName, Changed);
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/**
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* "Renamed" means that that newName was created as a result of the mv(1).
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*/
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JournalDelta(RelativePathPiece oldName, RelativePathPiece newName, Renamed);
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/**
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* "Replaced" means that that newName was overwritten by oldName as a result
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* of the mv(1).
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*/
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JournalDelta(RelativePathPiece oldName, RelativePathPiece newName, Replaced);
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~JournalDelta();
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/** the prior delta and its chain */
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JournalDeltaPtr previous;
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/** The current sequence range.
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* This is a range to accommodate merging a range into a single entry. */
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SequenceNumber fromSequence;
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SequenceNumber toSequence;
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/** The time at which the change was recorded.
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* This is a range to accommodate merging a range into a single entry. */
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std::chrono::steady_clock::time_point fromTime;
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std::chrono::steady_clock::time_point toTime;
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/** The snapshot hash that we started and ended up on.
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* This will often be the same unless we perform a checkout or make
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* a new snapshot from the snapshotable files in the overlay. */
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Hash fromHash;
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Hash toHash;
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/**
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* The set of files that changed in the overlay in this update, including
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* some information about the changes.
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*/
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std::unordered_map<RelativePath, PathChangeInfo> changedFilesInOverlay;
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/** The set of files that had differing status across a checkout or
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* some other operation that changes the snapshot hash */
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std::unordered_set<RelativePath> uncleanPaths;
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/** Merge the deltas running back from this delta for all deltas
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* whose toSequence is >= limitSequence.
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* The default limit value is 0 which is never assigned by the Journal
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* and thus indicates that all deltas should be merged.
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* if pruneAfterLimit is true and we stop due to hitting limitSequence,
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* then the returned delta will have previous=nullptr rather than
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* maintaining the chain.
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* If the limitSequence means that no deltas will match, returns nullptr.
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* */
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std::unique_ptr<JournalDelta> merge(
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SequenceNumber limitSequence = 0,
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bool pruneAfterLimit = false) const;
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private:
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void incRef() const noexcept;
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void decRef() const noexcept;
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bool isUnique() const noexcept;
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mutable std::atomic<size_t> refCount_{0};
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// For reference counting.
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friend class JournalDeltaPtr;
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};
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} // namespace eden
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} // namespace facebook
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