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9fa292b9ed
Reviewed By: genevievehelsel Differential Revision: D36429182 fbshipit-source-id: 7d355917abf463493c37139856810de13e1090ff
98 lines
2.7 KiB
C++
98 lines
2.7 KiB
C++
/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This software may be used and distributed according to the terms of the
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* GNU General Public License version 2.
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*/
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#pragma once
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#include <folly/Synchronized.h>
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#include "eden/fs/inodes/TreeInode.h"
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#include "eden/fs/utils/PathFuncs.h"
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namespace facebook::eden {
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/**
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* ParentInodeInfo contains information about an InodeBase's parent.
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*
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* This object hold the lock on the parent TreeInode's contents for as long as
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* it exists. This ensures that the Inode in question cannot be renamed or
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* unlinked while the ParentInodeInfo object exists.
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*
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* Note that we intentionally hold the parent TreeInode's contents lock, and
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* not this Inode's location_ lock. The location_ lock would also prevent
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* changes to the location, but this lock is very low-level in our lock
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* ordering scheme, and no other locks may be held while holding it. This
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* prevents us from doing many useful operations. Additionally, most
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* operations where we need to use the ParentInodeInfo requires us to hold the
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* parent's lock anyway.
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*/
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class ParentInodeInfo {
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public:
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ParentInodeInfo(
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PathComponentPiece name,
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TreeInodePtr parent,
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bool isUnlinked,
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folly::Synchronized<TreeInodeState>::LockedPtr contents)
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: name_(name),
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parent_(std::move(parent)),
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isUnlinked_(isUnlinked),
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parentContents_(std::move(contents)) {}
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/**
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* Get a pointer to the parent.
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*
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* This will return a null pointer if this the root inode.
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* In all other cases this will return non-null, including for unlinked
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* inodes.
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*
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* For unlinked inodes this returns a pointer to the inode that used to be
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* the parent just before this inode was unlinked. Note that in this case
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* the parent itself may also be unlinked.
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*/
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const TreeInodePtr& getParent() const {
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return parent_;
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}
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/**
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* Returns true if this inode has been unlinked from its parent.
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*/
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bool isUnlinked() const {
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return isUnlinked_;
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}
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/**
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* Get the name of this inode inside its parent.
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*
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* For unlinked inodes this returns its name just before it was unlinked.
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*/
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const PathComponent& getName() const {
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return name_;
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}
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/**
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* Get the locked contents of the parent inode.
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*
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* This returns a null pointer if this is the root inode, or if this inode is
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* unlinked.
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*/
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const folly::Synchronized<TreeInodeState>::LockedPtr& getParentContents()
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const {
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return parentContents_;
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}
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void reset() {
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if (parentContents_) {
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parentContents_.unlock();
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}
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}
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private:
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PathComponent name_;
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TreeInodePtr parent_;
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bool isUnlinked_;
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folly::Synchronized<TreeInodeState>::LockedPtr parentContents_;
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};
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} // namespace facebook::eden
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