dircache.h File Reference

#include <sys/types.h>
#include <atalk/directory.h>
#include <atalk/globals.h>
#include <atalk/volume.h>

Go to the source code of this file.

Macros
#define	MIN_DIRCACHE_SIZE   1024 /* 1K minimum (testing/constrained systems) */
#define	DEFAULT_DIRCACHE_SIZE   65536 /* 64K default (production) */
#define	MAX_DIRCACHE_SIZE   1048576 /* 1M maximum (high-memory servers) */
#define	DIRCACHE_FREE_QUANTUM   256
#define	DEFERRED_CHAIN_BATCH   16
#define	DIRCACHE   (1 << 0)
#define	DIDNAME_INDEX   (1 << 1)
#define	QUEUE_INDEX   (1 << 2)
#define	DIRCACHE_NOSHRINK   (1 << 3) /* Skip hash table shrink */
#define	DIRCACHE_ALL   (DIRCACHE|DIDNAME_INDEX|QUEUE_INDEX)

Functions
int	dircache_init (int reqsize)
	Initialize the dircache and indexes.
int	dircache_add (const struct vol *, struct dir *)
	create struct dir from struct path
void	dircache_remove (const struct vol *, struct dir *, int flag)
	Remove an entry from the dircache.
struct dir *	dircache_search_by_did (const struct vol *vol, cnid_t did)
	Search the dircache via a CNID for a directory.
struct dir *	dircache_search_by_name (const struct vol *, const struct dir *dir, char *name, size_t len)
	Search the cache via did/name hashtable.
void	dircache_dump (void)
	Dump dircache to /tmp/dircache.PID.
void	log_dircache_stat (void)
	Log dircache statistics.
int	dircache_set_validation_params (unsigned int freq)
	Set directory cache validation frequency.
void	dircache_reset_validation_counter (void)
	Reset validation counter for consistent testing.
void	dircache_report_invalid_entry (struct dir *dir)
	Report that a cache entry was invalid when actually used.
int	dircache_remove_children (const struct vol *vol, struct dir *dir)
	Remove all child entries of a directory from the dircache.
int	dircache_reindex_didname (const struct vol *vol, struct dir *dir)
	Re-insert entry into DID/name index after key change.
void	dircache_promote (struct dir *dir)
	Promote a cache entry to signal recency.
void	process_cache_hints (AFPObj *obj)
	Process cross-process dircache invalidation hints.
void	dircache_remove_children_defer (const struct vol *vol, struct dir *dir)
	Enqueue a deferred dircache_remove_children operation.
void	dircache_flush_deferred_for_vol (uint16_t vid)
	Process deferred cleanup entries for a closing volume synchronously.
int	dircache_has_deferred_work (void)
int	dircache_process_deferred_chain (void)
	Process one hash chain from the current deferred cleanup job.
void	dircache_rfork_shutdown (void)
	Shutdown the rfork cache — free remaining RFork LRU nodes and sentinel.

Variables
size_t	rfork_cache_used
size_t	rfork_cache_budget
size_t	rfork_max_entry_size
unsigned int	rfork_lru_count
q_t *	rfork_lru
unsigned long long	rfork_stat_lookups
unsigned long long	rfork_stat_hits
unsigned long long	rfork_stat_misses
unsigned long long	rfork_stat_added
unsigned long long	rfork_stat_evicted
unsigned long long	rfork_stat_invalidated
size_t	rfork_stat_used_max

Macro Definition Documentation

DEFAULT_DIRCACHE_SIZE

#define DEFAULT_DIRCACHE_SIZE   65536 /* 64K default (production) */

DEFERRED_CHAIN_BATCH

#define DEFERRED_CHAIN_BATCH   16

DIDNAME_INDEX

#define DIDNAME_INDEX   (1 << 1)

DIRCACHE

#define DIRCACHE   (1 << 0)

DIRCACHE_ALL

#define DIRCACHE_ALL   (DIRCACHE|DIDNAME_INDEX|QUEUE_INDEX)

DIRCACHE_FREE_QUANTUM

#define DIRCACHE_FREE_QUANTUM   256

DIRCACHE_NOSHRINK

#define DIRCACHE_NOSHRINK   (1 << 3) /* Skip hash table shrink */

MAX_DIRCACHE_SIZE

#define MAX_DIRCACHE_SIZE   1048576 /* 1M maximum (high-memory servers) */

MIN_DIRCACHE_SIZE

#define MIN_DIRCACHE_SIZE   1024 /* 1K minimum (testing/constrained systems) */

QUEUE_INDEX

#define QUEUE_INDEX   (1 << 2)

Function Documentation

dircache_add()

int dircache_add ( const struct vol * vol, struct dir * dir )

extern

create struct dir from struct path

Add a struct dir to the cache and its indexes. Supports both LRU mode (legacy) and ARC mode.

Parameters

[in]	vol	pointer to volume
[in]	dir	pointer to parent directory

Returns

0 on success, -1 on error which should result in an abort

dircache_dump()

void dircache_dump ( void )

extern

Dump dircache to /tmp/dircache.PID.

dircache_flush_deferred_for_vol()

void dircache_flush_deferred_for_vol ( uint16_t vid )

extern

Process deferred cleanup entries for a closing volume synchronously.

Precondition

: Worker is dormant (called during AFP command processing). Called from afp_closevol() before volume structures are freed.

dircache_has_deferred_work()

int dircache_has_deferred_work ( void )

extern

dircache_init()

int dircache_init ( int reqsize )

extern

Initialize the dircache and indexes.

This is called in child afpd initialization. The maximum cache size will be max(DEFAULT_DIRCACHE_SIZE, min(size, MAX_DIRCACHE_SIZE)). It initializes a hashtable which we use to store a directory cache in. It also initializes two indexes:

• a DID/name index on the main dircache
• a queue index on the dircache (LRU mode) or four queues (ARC mode)

Parameters

[in]

reqsize

requested maximum size from afp.conf

Returns

0 on success, -1 on error

dircache_process_deferred_chain()

int dircache_process_deferred_chain ( void )

extern

Process one hash chain from the current deferred cleanup job.

Called by idle worker. Walks a single hash chain, collects up to DEFERRED_CHAIN_BATCH matching children, and removes+frees them via dir_remove_and_free(). Entries matching curdir are skipped.

Returns

1 if more work remains, 0 if all deferred work is complete

dircache_promote()

void dircache_promote ( struct dir * dir )

extern

Promote a cache entry to signal recency.

Dispatches based on cache mode:

ARC mode (arc_list membership): T1/T2: arc_case_i() — move to MRU of T2 B1: arc_case_ii_adapt_and_replace() — promote ghost to T2 B2: arc_case_iii_adapt_and_replace() — promote ghost to T2

LRU mode: Move entry to MRU position of the LRU queue, so recently accessed entries are evicted last. Prevents actively-used entries from being evicted.

Parameters

[in,out]

dir

Cache entry to promote (required)

dircache_reindex_didname()

int dircache_reindex_didname ( const struct vol * vol, struct dir * dir )

extern

Re-insert entry into DID/name index after key change.

Called by dir_modify() after updating d_pdid / d_u_name. The caller MUST have already removed the entry from the DIDNAME_INDEX via dircache_remove(vol, dir, DIDNAME_INDEX) before calling this.

Parameters

[in]	vol	Volume (required)
[in]	dir	Entry with updated d_pdid / d_u_name (required)

Returns

0 on success, -1 on hash insert failure

dircache_remove()

void dircache_remove ( const struct vol * vol, struct dir * dir, int flags )

extern

Remove an entry from the dircache.

Callers outside of dircache.c should call this with flags = QUEUE_INDEX | DIDNAME_INDEX | DIRCACHE.

dircache_remove_children()

int dircache_remove_children ( const struct vol * vol, struct dir * dir )

extern

Remove all child entries of a directory from the dircache.

When a directory is renamed or moved, the full paths stored in the dircache become invalid for all child entries of the renamed dir. This function prunes orphaned child dircache entries of given dir. CNID entries use parent DIDs and name, and requre recursion to get the full path, therefore parent changes do not invalidate the CNIDs.

Parameters

[in]	vol	volume
[in]	dir	parent directory whose children should be removed

Returns

0 on success, -1 if curdir was removed and recovery failed

dircache_remove_children_defer()

void dircache_remove_children_defer ( const struct vol * vol, struct dir * dir )

extern

Enqueue a deferred dircache_remove_children operation.

O(1) enqueue — the idle worker performs the actual hash scan during poll() idle periods. Falls back to synchronous removal if the worker is not active or the queue is full.

dircache_report_invalid_entry()

void dircache_report_invalid_entry ( struct dir * dir )

extern

Report that a cache entry was invalid when actually used.

This function should be called when a cached directory entry that was returned without validation (for performance) turns out to be invalid when actually accessed (e.g., file doesn't exist, has been modified, etc). This helps track the effectiveness of the validation frequency setting.

Parameters

[in]

dir

The directory entry that was found to be invalid

dircache_reset_validation_counter()

void dircache_reset_validation_counter ( void )

extern

Reset validation counter for consistent testing.

Resets the global validation counter to ensure predictable validation patterns between test runs or configuration changes.

dircache_rfork_shutdown()

void dircache_rfork_shutdown ( void )

extern

Shutdown the rfork cache — free remaining RFork LRU nodes and sentinel.

Called from the child shutdown path after log_dircache_stat(). Frees the qnodes (rfork data buffers are reclaimed by exit()) and the LRU sentinel.

dircache_search_by_did()

struct dir * dircache_search_by_did ( const struct vol * vol, cnid_t cnid )

extern

Search the dircache via a CNID for a directory.

Found cache entries are expunged if both the parent directory st_ctime and the objects st_ctime are modified. This func builds on the fact, that all our code only ever needs to and does search the dircache by CNID expecting directories to be returned, but not files. Thus (1) if we find a file for a given CNID we (1a) remove it from the cache (1b) return NULL indicating nothing found (2) we can then use d_fullpath to stat the directory

Parameters

[in]	vol	pointer to struct vol
[in]	cnid	CNID of the directory to search

Returns

Pointer to struct dir if found, else NULL

dircache_search_by_name()

struct dir * dircache_search_by_name ( const struct vol * vol, const struct dir * dir, char * name, size_t len )

extern

Search the cache via did/name hashtable.

Found cache entries are expunged if both the parent directory st_ctime and the objects st_ctime are modified.

Parameters

[in]	vol	volume
[in]	dir	directory
[in]	name	name (server side encoding)
[in]	len	strlen of name

Returns

pointer to struct dir if found in cache, else NULL

dircache_set_validation_params()

int dircache_set_validation_params ( unsigned int freq )

extern

Set directory cache validation frequency.

Allows runtime configuration of cache validation behavior for performance tuning. Lower validation frequency improves performance but may delay detection of external filesystem changes.

Parameters

[in]

freq

validation frequency (1 = validate every access, 100 = every 100th access)

Returns

0 on success, -1 on invalid parameters

log_dircache_stat()

void log_dircache_stat ( void )

extern

Log dircache statistics.

Includes hit ratio percentage for monitoring cache effectiveness, validation-specific metrics to monitor performance impact of the optimization changes, and username for tracking per-user stats. Shows both expunged (caught by validation) and invalid_on_use (missed by validation).

process_cache_hints()

void process_cache_hints ( AFPObj * obj )

extern

Process cross-process dircache invalidation hints.

Called from the DSI command loop after each AFP command completes. Uses direct hash_lookup() on the CNID hash table to support BOTH files (DIRF_ISFILE) and directories — dircache_search_by_did() is unsuitable because it actively removes file entries.

Dispatches on hint type:

• CACHE_HINT_REFRESH: ostat() + dir_modify() — stat refresh, AD invalidation
• CACHE_HINT_DELETE: direct dir_remove() — no ostat needed
• CACHE_HINT_DELETE_CHILDREN: dircache_remove_children() + parent cleanup

Variable Documentation

rfork_cache_budget

size_t rfork_cache_budget

extern

rfork_cache_used

size_t rfork_cache_used

extern

rfork_lru

q_t* rfork_lru

extern

rfork_lru_count

unsigned int rfork_lru_count

extern

rfork_max_entry_size

size_t rfork_max_entry_size

extern

rfork_stat_added

unsigned long long rfork_stat_added

extern

rfork_stat_evicted

unsigned long long rfork_stat_evicted

extern

rfork_stat_hits

unsigned long long rfork_stat_hits

extern

rfork_stat_invalidated

unsigned long long rfork_stat_invalidated

extern

rfork_stat_lookups

unsigned long long rfork_stat_lookups

extern

rfork_stat_misses

unsigned long long rfork_stat_misses

extern

rfork_stat_used_max

size_t rfork_stat_used_max

extern