A visitor for the filesystem traversal and reduction algorithm. More...

#include "reduce.hpp"

Inheritance diagram for llfio_v2_xxx::algorithm::reduce_visitor:

Public Member Functions
constexpr	reduce_visitor ()
	Constructs an instance with the default timeout of ten seconds.

constexpr	reduce_visitor (std::chrono::steady_clock::duration _timeout)
	Constructs an instance with the specified timeout.

virtual result< directory_handle >	directory_open_failed (void *data, result< void >::error_type &&error, const directory_handle &dirh, path_view leaf, size_t depth) noexcept override
	This override ignores failures to traverse into the directory, and tries renaming the item into the base directory.

virtual result< void >	post_enumeration (void *data, const directory_handle &dirh, directory_handle::buffers_type &contents, size_t depth) noexcept override
	This override invokes deletion of all non-directory items. If there are no directory items, also deletes the directory.

virtual result< bool >	unlink_failed (void *data, result< void >::error_type &&error, const directory_handle &dirh, directory_entry &entry, size_t depth) noexcept
	Called when the unlink of a file entry failed. The default implementation attempts to rename the entry into the base directory. If your reimplementation achieves the unlink, return true. More...

virtual result< bool >	rename_failed (void *data, result< void >::error_type &&error, const directory_handle &dirh, directory_entry &entry, size_t depth) noexcept
	Called when the rename of a file entry into the base directory failed. The default implementation ignores the failure. If your reimplementation achieves the rename, return true. More...

virtual result< void >	reduction_round (void *data, size_t round_completed, size_t items_unlinked, size_t items_remaining) noexcept
	Called when we have performed a single full round of reduction. More...

virtual result< bool >	pre_enumeration (void *data, const directory_handle &dirh, size_t depth) noexcept
	Called to decide whether to enumerate a directory. More...

virtual result< void >	stack_updated (void *data, size_t dirs_processed, size_t known_dirs_remaining, size_t depth_processed, size_t known_depth_remaining) noexcept
	Called whenever the traversed stack of directory hierarchy is updated. This can act as an estimated progress indicator, or to give an accurate progress indicator by matching it against a previous traversal. More...

virtual result< size_t >	finished (void *data, result< size_t > result) noexcept
	Called when a traversal finishes, whether due to success or failure. Always called from the original thread.

Public Attributes
std::chrono::steady_clock::duration	timeout {std::chrono::seconds(10)}

std::chrono::steady_clock::time_point	begin

Detailed Description

A visitor for the filesystem traversal and reduction algorithm.

Note that at any time, returning a failure causes reduce() to exit as soon as possible with the same failure.

You can override the members here inherited from traverse_visitor, however note that reduce() is entirely implemented using traverse(), so not calling the implementations here will affect operation.

Member Function Documentation

◆ pre_enumeration()

virtual result<bool> llfio_v2_xxx::algorithm::traverse_visitor::pre_enumeration	(	void *	data,
		const directory_handle &	dirh,
		size_t	depth
	)

inlinevirtualnoexceptinherited

Called to decide whether to enumerate a directory.

Note that it is more efficient to ignore the directory entry in post_enumeration() than to ignore it here, as a handle is opened for the directory before this callback. Equally, if you need that handle to inspect the directory e.g. to check if one is entering a different filesystem from the root, here is best.

The default returns true.

Note: May be called from multiple kernel threads concurrently.

     {
       (void) data;
       (void) dirh;
       (void) depth;
       return true;
     }

◆ reduction_round()

virtual result<void> llfio_v2_xxx::algorithm::reduce_visitor::reduction_round	(	void *	data,
		size_t	round_completed,
		size_t	items_unlinked,
		size_t	items_remaining
	)

inlinevirtualnoexcept

Called when we have performed a single full round of reduction.

Note: Always called from the original kernel thread.

     {
       (void) data;
       (void) round_completed;
       (void) items_unlinked;
       if(items_remaining > 0)
       {
         if(begin == std::chrono::steady_clock::time_point())
         {
           begin = std::chrono::steady_clock::now();
         }
         else if((std::chrono::steady_clock::now() - begin) > timeout)
         {
           return errc::timed_out;
         }
       }
       return success();
     }

◆ rename_failed()

virtual result<bool> llfio_v2_xxx::algorithm::reduce_visitor::rename_failed	(	void *	data,
		result< void >::error_type &&	error,
		const directory_handle &	dirh,
		directory_entry &	entry,
		size_t	depth
	)

inlinevirtualnoexcept

Called when the rename of a file entry into the base directory failed. The default implementation ignores the failure. If your reimplementation achieves the rename, return true.

Note: May be called from multiple kernel threads concurrently.

     {
       (void) data;
       (void) error;
       (void) dirh;
       (void) entry;
       (void) depth;
       return false;
     }

◆ stack_updated()

virtual result<void> llfio_v2_xxx::algorithm::traverse_visitor::stack_updated	(	void *	data,
		size_t	dirs_processed,
		size_t	known_dirs_remaining,
		size_t	depth_processed,
		size_t	known_depth_remaining
	)

inlinevirtualnoexceptinherited

Called whenever the traversed stack of directory hierarchy is updated. This can act as an estimated progress indicator, or to give an accurate progress indicator by matching it against a previous traversal.

Parameters

data	The third party data pointer passed to `traverse()`.
dirs_processed	The total number of directories traversed so far.
known_dirs_remaining	The currently known number of directories awaiting traversal.
depth_processed	How many levels deep we have already completely traversed.
known_depth_remaining	The currently known number of levels we shall traverse.

Note: May be called from multiple kernel threads concurrently.

     {
       (void) data;
       (void) dirs_processed;
       (void) known_dirs_remaining;
       (void) depth_processed;
       (void) known_depth_remaining;
       return success();
     }

◆ unlink_failed()

virtual result<bool> llfio_v2_xxx::algorithm::reduce_visitor::unlink_failed	(	void *	data,
		result< void >::error_type &&	error,
		const directory_handle &	dirh,
		directory_entry &	entry,
		size_t	depth
	)

virtualnoexcept

Called when the unlink of a file entry failed. The default implementation attempts to rename the entry into the base directory. If your reimplementation achieves the unlink, return true.

Note: May be called from multiple kernel threads concurrently.

The documentation for this struct was generated from the following file:

include/llfio/v2.0/algorithm/reduce.hpp

Public Member Functions