Adding upstream version 3.5.24.upstream/3.5.24upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1121 insertions, 0 deletions

diff --git a/src/util/dict_cache.c b/src/util/dict_cache.c
new file mode 100644
index 0000000..2259f12
--- /dev/null
+++ b/src/util/dict_cache.c
@@ -0,0 +1,1121 @@
+/*++
+/* NAME
+/*	dict_cache 3
+/* SUMMARY
+/*	External cache manager
+/* SYNOPSIS
+/*	#include <dict_cache.h>
+/*
+/*	DICT_CACHE *dict_cache_open(dbname, open_flags, dict_flags)
+/*	const char *dbname;
+/*	int	open_flags;
+/*	int	dict_flags;
+/*
+/*	void	dict_cache_close(cache)
+/*	DICT_CACHE *cache;
+/*
+/*	const char *dict_cache_lookup(cache, cache_key)
+/*	DICT_CACHE *cache;
+/*	const char *cache_key;
+/*
+/*	int	dict_cache_update(cache, cache_key, cache_val)
+/*	DICT_CACHE *cache;
+/*	const char *cache_key;
+/*	const char *cache_val;
+/*
+/*	int	dict_cache_delete(cache, cache_key)
+/*	DICT_CACHE *cache;
+/*	const char *cache_key;
+/*
+/*	int	dict_cache_sequence(cache, first_next, cache_key, cache_val)
+/*	DICT_CACHE *cache;
+/*	int	first_next;
+/*	const char **cache_key;
+/*	const char **cache_val;
+/* AUXILIARY FUNCTIONS
+/*	void	dict_cache_control(cache, name, value, ...)
+/*	DICT_CACHE *cache;
+/*	int	name;
+/*
+/*	typedef int (*DICT_CACHE_VALIDATOR_FN) (const char *cache_key,
+/*		const char *cache_val, void *context);
+/*
+/*	const char *dict_cache_name(cache)
+/*	DICT_CACHE	*cache;
+/* DESCRIPTION
+/*	This module maintains external cache files with support
+/*	for expiration. The underlying table must implement the
+/*	"lookup", "update", "delete" and "sequence" operations.
+/*
+/*	Although this API is similar to the one documented in
+/*	dict_open(3), there are subtle differences in the interaction
+/*	between the iterators that access all cache elements, and
+/*	other operations that access individual cache elements.
+/*
+/*	In particular, when a "sequence" or "cleanup" operation is
+/*	in progress the cache intercepts requests to delete the
+/*	"current" entry, as this would cause some databases to
+/*	mis-behave. Instead, the cache implements a "delete behind"
+/*	strategy, and deletes such an entry after the "sequence"
+/*	or "cleanup" operation moves on to the next cache element.
+/*	The "delete behind" strategy also affects the cache lookup
+/*	and update operations as detailed below.
+/*
+/*	dict_cache_open() is a wrapper around the dict_open()
+/*	function.  It opens the specified cache and returns a handle
+/*	that must be used for subsequent access. This function does
+/*	not return in case of error.
+/*
+/*	dict_cache_close() closes the specified cache and releases
+/*	memory that was allocated by dict_cache_open(), and terminates
+/*	any thread that was started with dict_cache_control().
+/*
+/*	dict_cache_lookup() looks up the specified cache entry.
+/*	The result value is a null pointer when the cache entry was
+/*	not found, or when the entry is scheduled for "delete
+/*	behind".
+/*
+/*	dict_cache_update() updates the specified cache entry. If
+/*	the entry is scheduled for "delete behind", the delete
+/*	operation is canceled (because of this, the cache must be
+/*	opened with DICT_FLAG_DUP_REPLACE). This function does not
+/*	return in case of error.
+/*
+/*	dict_cache_delete() removes the specified cache entry.  If
+/*	this is the "current" entry of a "sequence" operation, the
+/*	entry is scheduled for "delete behind". The result value
+/*	is zero when the entry was found.
+/*
+/*	dict_cache_sequence() iterates over the specified cache and
+/*	returns each entry in an implementation-defined order.  The
+/*	result value is zero when a cache entry was found.
+/*
+/*	Important: programs must not use both dict_cache_sequence()
+/*	and the built-in cache cleanup feature.
+/*
+/*	dict_cache_control() provides control over the built-in
+/*	cache cleanup feature and logging. The arguments are a list
+/*	of macros with zero or more arguments, terminated with
+/*	CA_DICT_CACHE_CTL_END which has none.  The following lists
+/*	the macros and corresponding argument types.
+/* .IP "CA_DICT_CACHE_CTL_FLAGS(int flags)"
+/*	The arguments to this command are the bit-wise OR of zero
+/*	or more of the following:
+/* .RS
+/* .IP CA_DICT_CACHE_CTL_FLAG_VERBOSE
+/*	Enable verbose logging of cache activity.
+/* .IP CA_DICT_CACHE_CTL_FLAG_EXP_SUMMARY
+/*	Log cache statistics after each cache cleanup run.
+/* .RE
+/* .IP "CA_DICT_CACHE_CTL_INTERVAL(int interval)"
+/*	The interval between cache cleanup runs.  Specify a null
+/*	validator or interval to stop cache cleanup.
+/* .IP "CA_DICT_CACHE_CTL_VALIDATOR(DICT_CACHE_VALIDATOR_FN validator)"
+/*	An application call-back routine that returns non-zero when
+/*	a cache entry should be kept. The call-back function should
+/*	not make changes to the cache. Specify a null validator or
+/*	interval to stop cache cleanup.
+/* .IP "CA_DICT_CACHE_CTL_CONTEXT(void *context)"
+/*	Application context that is passed to the validator function.
+/* .RE
+/* .PP
+/*	dict_cache_name() returns the name of the specified cache.
+/*
+/*	Arguments:
+/* .IP "dbname, open_flags, dict_flags"
+/*	These are passed unchanged to dict_open(). The cache must
+/*	be opened with DICT_FLAG_DUP_REPLACE.
+/* .IP cache
+/*	Cache handle created with dict_cache_open().
+/* .IP cache_key
+/*	Cache lookup key.
+/* .IP cache_val
+/*	Information that is stored under a cache lookup key.
+/* .IP first_next
+/*	One of DICT_SEQ_FUN_FIRST (first cache element) or
+/*	DICT_SEQ_FUN_NEXT (next cache element).
+/* .sp
+/*	Note: there is no "stop" request. To ensure that the "delete
+/*	behind" strategy does not interfere with database access,
+/*	allow dict_cache_sequence() to run to completion.
+/* .IP table
+/*	A bare dictonary handle.
+/* DIAGNOSTICS
+/*	When a request is satisfied, the lookup routine returns
+/*	non-null, and the update, delete and sequence routines
+/*	return zero.  The cache->error value is zero when a request
+/*	could not be satisfied because an item did not exist (delete,
+/*	sequence) or if it could not be updated. The cache->error
+/*	value is non-zero only when a request could not be satisfied,
+/*	and the cause was a database error.
+/*
+/*	Cache access errors are logged with a warning message. To
+/*	avoid spamming the log, each type of operation logs no more
+/*	than one cache access error per second, per cache. Specify
+/*	the DICT_CACHE_FLAG_VERBOSE flag (see above) to log all
+/*	warnings.
+/* BUGS
+/*	There should be a way to suspend automatic program suicide
+/*	until a cache cleanup run is completed. Some entries may
+/*	never be removed when the process max_idle time is less
+/*	than the time needed to make a full pass over the cache.
+/*
+/*	The delete-behind strategy assumes that all updates are
+/*	made by a single process. Otherwise, delete-behind may
+/*	remove an entry that was updated after it was scheduled for
+/*	deletion.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* HISTORY
+/* .ad
+/* .fi
+/*	A predecessor of this code was written first for the Postfix
+/*	tlsmgr(8) daemon.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <string.h>
+#include <stdlib.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <dict.h>
+#include <mymalloc.h>
+#include <events.h>
+#include <dict_cache.h>
+
+/* Application-specific. */
+
+ /*
+  * XXX Deleting entries while enumerating a map can he tricky. Some map
+  * types have a concept of cursor and support a "delete the current element"
+  * operation. Some map types without cursors don't behave well when the
+  * current first/next entry is deleted (example: with Berkeley DB < 2, the
+  * "next" operation produces garbage). To avoid trouble, we delete an entry
+  * after advancing the current first/next position beyond it; we use the
+  * same strategy with application requests to delete the current entry.
+  */
+
+ /*
+  * Opaque data structure. Use dict_cache_name() to access the name of the
+  * underlying database.
+  */
+struct DICT_CACHE {
+    char   *name;			/* full name including proxy: */
+    int     cache_flags;		/* see below */
+    int     user_flags;			/* logging */
+    DICT   *db;				/* database handle */
+    int     error;			/* last operation only */
+
+    /* Delete-behind support. */
+    char   *saved_curr_key;		/* "current" cache lookup key */
+    char   *saved_curr_val;		/* "current" cache lookup result */
+
+    /* Cleanup support. */
+    int     exp_interval;		/* time between cleanup runs */
+    DICT_CACHE_VALIDATOR_FN exp_validator;	/* expiration call-back */
+    void   *exp_context;		/* call-back context */
+    int     retained;			/* entries retained in cleanup run */
+    int     dropped;			/* entries removed in cleanup run */
+
+    /* Rate-limited logging support. */
+    int     log_delay;
+    time_t  upd_log_stamp;		/* last update warning */
+    time_t  get_log_stamp;		/* last lookup warning */
+    time_t  del_log_stamp;		/* last delete warning */
+    time_t  seq_log_stamp;		/* last sequence warning */
+};
+
+#define DC_FLAG_DEL_SAVED_CURRENT_KEY	(1<<0)	/* delete-behind is scheduled */
+
+ /*
+  * Don't log cache access errors more than once per second.
+  */
+#define DC_DEF_LOG_DELAY	1
+
+ /*
+  * Macros to make obscure code more readable.
+  */
+#define DC_SCHEDULE_FOR_DELETE_BEHIND(cp) \
+    ((cp)->cache_flags |= DC_FLAG_DEL_SAVED_CURRENT_KEY)
+
+#define DC_MATCH_SAVED_CURRENT_KEY(cp, cache_key) \
+    ((cp)->saved_curr_key && strcmp((cp)->saved_curr_key, (cache_key)) == 0)
+
+#define DC_IS_SCHEDULED_FOR_DELETE_BEHIND(cp) \
+    (/* NOT: (cp)->saved_curr_key && */ \
+	((cp)->cache_flags & DC_FLAG_DEL_SAVED_CURRENT_KEY) != 0)
+
+#define DC_CANCEL_DELETE_BEHIND(cp) \
+    ((cp)->cache_flags &= ~DC_FLAG_DEL_SAVED_CURRENT_KEY)
+
+ /*
+  * Special key to store the time of the last cache cleanup run completion.
+  */
+#define DC_LAST_CACHE_CLEANUP_COMPLETED "_LAST_CACHE_CLEANUP_COMPLETED_"
+
+/* dict_cache_lookup - load entry from cache */
+
+const char *dict_cache_lookup(DICT_CACHE *cp, const char *cache_key)
+{
+    const char *myname = "dict_cache_lookup";
+    const char *cache_val;
+    DICT   *db = cp->db;
+
+    /*
+     * Search for the cache entry. Don't return an entry that is scheduled
+     * for delete-behind.
+     */
+    if (DC_IS_SCHEDULED_FOR_DELETE_BEHIND(cp)
+	&& DC_MATCH_SAVED_CURRENT_KEY(cp, cache_key)) {
+	if (cp->user_flags & DICT_CACHE_FLAG_VERBOSE)
+	    msg_info("%s: key=%s (pretend not found  - scheduled for deletion)",
+		     myname, cache_key);
+	DICT_ERR_VAL_RETURN(cp, DICT_ERR_NONE, (char *) 0);
+    } else {
+	cache_val = dict_get(db, cache_key);
+	if (cache_val == 0 && db->error != 0)
+	    msg_rate_delay(&cp->get_log_stamp, cp->log_delay, msg_warn,
+			   "%s: cache lookup for '%s' failed due to error",
+			   cp->name, cache_key);
+	if (cp->user_flags & DICT_CACHE_FLAG_VERBOSE)
+	    msg_info("%s: key=%s value=%s", myname, cache_key,
+		     cache_val ? cache_val : db->error ?
+		     "error" : "(not found)");
+	DICT_ERR_VAL_RETURN(cp, db->error, cache_val);
+    }
+}
+
+/* dict_cache_update - save entry to cache */
+
+int     dict_cache_update(DICT_CACHE *cp, const char *cache_key,
+			          const char *cache_val)
+{
+    const char *myname = "dict_cache_update";
+    DICT   *db = cp->db;
+    int     put_res;
+
+    /*
+     * Store the cache entry and cancel the delete-behind operation.
+     */
+    if (DC_IS_SCHEDULED_FOR_DELETE_BEHIND(cp)
+	&& DC_MATCH_SAVED_CURRENT_KEY(cp, cache_key)) {
+	if (cp->user_flags & DICT_CACHE_FLAG_VERBOSE)
+	    msg_info("%s: cancel delete-behind for key=%s", myname, cache_key);
+	DC_CANCEL_DELETE_BEHIND(cp);
+    }
+    if (cp->user_flags & DICT_CACHE_FLAG_VERBOSE)
+	msg_info("%s: key=%s value=%s", myname, cache_key, cache_val);
+    put_res = dict_put(db, cache_key, cache_val);
+    if (put_res != 0)
+	msg_rate_delay(&cp->upd_log_stamp, cp->log_delay, msg_warn,
+		  "%s: could not update entry for %s", cp->name, cache_key);
+    DICT_ERR_VAL_RETURN(cp, db->error, put_res);
+}
+
+/* dict_cache_delete - delete entry from cache */
+
+int     dict_cache_delete(DICT_CACHE *cp, const char *cache_key)
+{
+    const char *myname = "dict_cache_delete";
+    int     del_res;
+    DICT   *db = cp->db;
+
+    /*
+     * Delete the entry, unless we would delete the current first/next entry.
+     * In that case, schedule the "current" entry for delete-behind to avoid
+     * mis-behavior by some databases.
+     */
+    if (DC_MATCH_SAVED_CURRENT_KEY(cp, cache_key)) {
+	DC_SCHEDULE_FOR_DELETE_BEHIND(cp);
+	if (cp->user_flags & DICT_CACHE_FLAG_VERBOSE)
+	    msg_info("%s: key=%s (current entry - schedule for delete-behind)",
+		     myname, cache_key);
+	DICT_ERR_VAL_RETURN(cp, DICT_ERR_NONE, DICT_STAT_SUCCESS);
+    } else {
+	del_res = dict_del(db, cache_key);
+	if (del_res != 0)
+	    msg_rate_delay(&cp->del_log_stamp, cp->log_delay, msg_warn,
+		  "%s: could not delete entry for %s", cp->name, cache_key);
+	if (cp->user_flags & DICT_CACHE_FLAG_VERBOSE)
+	    msg_info("%s: key=%s (%s)", myname, cache_key,
+		     del_res == 0 ? "found" :
+		     db->error ? "error" : "not found");
+	DICT_ERR_VAL_RETURN(cp, db->error, del_res);
+    }
+}
+
+/* dict_cache_sequence - look up the first/next cache entry */
+
+int     dict_cache_sequence(DICT_CACHE *cp, int first_next,
+			            const char **cache_key,
+			            const char **cache_val)
+{
+    const char *myname = "dict_cache_sequence";
+    int     seq_res;
+    const char *raw_cache_key;
+    const char *raw_cache_val;
+    char   *previous_curr_key;
+    char   *previous_curr_val;
+    DICT   *db = cp->db;
+
+    /*
+     * Find the first or next database entry. Hide the record with the cache
+     * cleanup completion time stamp.
+     */
+    seq_res = dict_seq(db, first_next, &raw_cache_key, &raw_cache_val);
+    if (seq_res == 0
+	&& strcmp(raw_cache_key, DC_LAST_CACHE_CLEANUP_COMPLETED) == 0)
+	seq_res =
+	    dict_seq(db, DICT_SEQ_FUN_NEXT, &raw_cache_key, &raw_cache_val);
+    if (cp->user_flags & DICT_CACHE_FLAG_VERBOSE)
+	msg_info("%s: key=%s value=%s", myname,
+		 seq_res == 0 ? raw_cache_key : db->error ?
+		 "(error)" : "(not found)",
+		 seq_res == 0 ? raw_cache_val : db->error ?
+		 "(error)" : "(not found)");
+    if (db->error)
+	msg_rate_delay(&cp->seq_log_stamp, cp->log_delay, msg_warn,
+		       "%s: sequence error", cp->name);
+
+    /*
+     * Save the current cache_key and cache_val before they are clobbered by
+     * our own delete operation below. This also prevents surprises when the
+     * application accesses the database after this function returns.
+     * 
+     * We also use the saved cache_key to protect the current entry against
+     * application delete requests.
+     */
+    previous_curr_key = cp->saved_curr_key;
+    previous_curr_val = cp->saved_curr_val;
+    if (seq_res == 0) {
+	cp->saved_curr_key = mystrdup(raw_cache_key);
+	cp->saved_curr_val = mystrdup(raw_cache_val);
+    } else {
+	cp->saved_curr_key = 0;
+	cp->saved_curr_val = 0;
+    }
+
+    /*
+     * Delete behind.
+     */
+    if (db->error == 0 && DC_IS_SCHEDULED_FOR_DELETE_BEHIND(cp)) {
+	DC_CANCEL_DELETE_BEHIND(cp);
+	if (cp->user_flags & DICT_CACHE_FLAG_VERBOSE)
+	    msg_info("%s: delete-behind key=%s value=%s",
+		     myname, previous_curr_key, previous_curr_val);
+	if (dict_del(db, previous_curr_key) != 0)
+	    msg_rate_delay(&cp->del_log_stamp, cp->log_delay, msg_warn,
+			   "%s: could not delete entry for %s",
+			   cp->name, previous_curr_key);
+    }
+
+    /*
+     * Clean up previous iteration key and value.
+     */
+    if (previous_curr_key)
+	myfree(previous_curr_key);
+    if (previous_curr_val)
+	myfree(previous_curr_val);
+
+    /*
+     * Return the result.
+     */
+    *cache_key = (cp)->saved_curr_key;
+    *cache_val = (cp)->saved_curr_val;
+    DICT_ERR_VAL_RETURN(cp, db->error, seq_res);
+}
+
+/* dict_cache_delete_behind_reset - reset "delete behind" state */
+
+static void dict_cache_delete_behind_reset(DICT_CACHE *cp)
+{
+#define FREE_AND_WIPE(s) do { if (s) { myfree(s); (s) = 0; } } while (0)
+
+    DC_CANCEL_DELETE_BEHIND(cp);
+    FREE_AND_WIPE(cp->saved_curr_key);
+    FREE_AND_WIPE(cp->saved_curr_val);
+}
+
+/* dict_cache_clean_stat_log_reset - log and reset cache cleanup statistics */
+
+static void dict_cache_clean_stat_log_reset(DICT_CACHE *cp,
+					            const char *full_partial)
+{
+    if (cp->user_flags & DICT_CACHE_FLAG_STATISTICS)
+	msg_info("cache %s %s cleanup: retained=%d dropped=%d entries",
+		 cp->name, full_partial, cp->retained, cp->dropped);
+    cp->retained = cp->dropped = 0;
+}
+
+/* dict_cache_clean_event - examine one cache entry */
+
+static void dict_cache_clean_event(int unused_event, void *cache_context)
+{
+    const char *myname = "dict_cache_clean_event";
+    DICT_CACHE *cp = (DICT_CACHE *) cache_context;
+    const char *cache_key;
+    const char *cache_val;
+    int     next_interval;
+    VSTRING *stamp_buf;
+    int     first_next;
+
+    /*
+     * We interleave cache cleanup with other processing, so that the
+     * application's service remains available, with perhaps increased
+     * latency.
+     */
+
+    /*
+     * Start a new cache cleanup run.
+     */
+    if (cp->saved_curr_key == 0) {
+	cp->retained = cp->dropped = 0;
+	first_next = DICT_SEQ_FUN_FIRST;
+	if (cp->user_flags & DICT_CACHE_FLAG_VERBOSE)
+	    msg_info("%s: start %s cache cleanup", myname, cp->name);
+    }
+
+    /*
+     * Continue a cache cleanup run in progress.
+     */
+    else {
+	first_next = DICT_SEQ_FUN_NEXT;
+    }
+
+    /*
+     * Examine one cache entry.
+     */
+    if (dict_cache_sequence(cp, first_next, &cache_key, &cache_val) == 0) {
+	if (cp->exp_validator(cache_key, cache_val, cp->exp_context) == 0) {
+	    DC_SCHEDULE_FOR_DELETE_BEHIND(cp);
+	    cp->dropped++;
+	    if (cp->user_flags & DICT_CACHE_FLAG_VERBOSE)
+		msg_info("%s: drop %s cache entry for %s",
+			 myname, cp->name, cache_key);
+	} else {
+	    cp->retained++;
+	    if (cp->user_flags & DICT_CACHE_FLAG_VERBOSE)
+		msg_info("%s: keep %s cache entry for %s",
+			 myname, cp->name, cache_key);
+	}
+	next_interval = 0;
+    }
+
+    /*
+     * Cache cleanup completed. Report vital statistics.
+     */
+    else if (cp->error != 0) {
+	msg_warn("%s: cache cleanup scan terminated due to error", cp->name);
+	dict_cache_clean_stat_log_reset(cp, "partial");
+	next_interval = cp->exp_interval;
+    } else {
+	if (cp->user_flags & DICT_CACHE_FLAG_VERBOSE)
+	    msg_info("%s: done %s cache cleanup scan", myname, cp->name);
+	dict_cache_clean_stat_log_reset(cp, "full");
+	stamp_buf = vstring_alloc(100);
+	vstring_sprintf(stamp_buf, "%ld", (long) event_time());
+	dict_put(cp->db, DC_LAST_CACHE_CLEANUP_COMPLETED,
+		 vstring_str(stamp_buf));
+	vstring_free(stamp_buf);
+	next_interval = cp->exp_interval;
+    }
+    event_request_timer(dict_cache_clean_event, cache_context, next_interval);
+}
+
+/* dict_cache_control - schedule or stop the cache cleanup thread */
+
+void    dict_cache_control(DICT_CACHE *cp,...)
+{
+    const char *myname = "dict_cache_control";
+    const char *last_done;
+    time_t  next_interval;
+    int     cache_cleanup_is_active = (cp->exp_validator && cp->exp_interval);
+    va_list ap;
+    int     name;
+
+    /*
+     * Update the control settings.
+     */
+    va_start(ap, cp);
+    while ((name = va_arg(ap, int)) > 0) {
+	switch (name) {
+	case DICT_CACHE_CTL_END:
+	    break;
+	case DICT_CACHE_CTL_FLAGS:
+	    cp->user_flags = va_arg(ap, int);
+	    cp->log_delay = (cp->user_flags & DICT_CACHE_FLAG_VERBOSE) ?
+		0 : DC_DEF_LOG_DELAY;
+	    break;
+	case DICT_CACHE_CTL_INTERVAL:
+	    cp->exp_interval = va_arg(ap, int);
+	    if (cp->exp_interval < 0)
+		msg_panic("%s: bad %s cache cleanup interval %d",
+			  myname, cp->name, cp->exp_interval);
+	    break;
+	case DICT_CACHE_CTL_VALIDATOR:
+	    cp->exp_validator = va_arg(ap, DICT_CACHE_VALIDATOR_FN);
+	    break;
+	case DICT_CACHE_CTL_CONTEXT:
+	    cp->exp_context = va_arg(ap, void *);
+	    break;
+	default:
+	    msg_panic("%s: bad command: %d", myname, name);
+	}
+    }
+    va_end(ap);
+
+    /*
+     * Schedule the cache cleanup thread.
+     */
+    if (cp->exp_interval && cp->exp_validator) {
+
+	/*
+	 * Sanity checks.
+	 */
+	if (cache_cleanup_is_active)
+	    msg_panic("%s: %s cache cleanup is already scheduled",
+		      myname, cp->name);
+
+	/*
+	 * The next start time depends on the last completion time.
+	 */
+#define NEXT_START(last, delta) ((delta) + (unsigned long) atol(last))
+#define NOW	(time((time_t *) 0))		/* NOT: event_time() */
+
+	if ((last_done = dict_get(cp->db, DC_LAST_CACHE_CLEANUP_COMPLETED)) == 0
+	    || (next_interval = (NEXT_START(last_done, cp->exp_interval) - NOW)) < 0)
+	    next_interval = 0;
+	if (next_interval > cp->exp_interval)
+	    next_interval = cp->exp_interval;
+	if ((cp->user_flags & DICT_CACHE_FLAG_VERBOSE) && next_interval > 0)
+	    msg_info("%s cache cleanup will start after %ds",
+		     cp->name, (int) next_interval);
+	event_request_timer(dict_cache_clean_event, (void *) cp,
+			    (int) next_interval);
+    }
+
+    /*
+     * Cancel the cache cleanup thread.
+     */
+    else if (cache_cleanup_is_active) {
+	if (cp->retained || cp->dropped)
+	    dict_cache_clean_stat_log_reset(cp, "partial");
+	dict_cache_delete_behind_reset(cp);
+	event_cancel_timer(dict_cache_clean_event, (void *) cp);
+    }
+}
+
+/* dict_cache_open - open cache file */
+
+DICT_CACHE *dict_cache_open(const char *dbname, int open_flags, int dict_flags)
+{
+    DICT_CACHE *cp;
+    DICT   *dict;
+
+    /*
+     * Open the database as requested. Don't attempt to second-guess the
+     * application.
+     */
+    dict = dict_open(dbname, open_flags, dict_flags);
+
+    /*
+     * Create the DICT_CACHE object.
+     */
+    cp = (DICT_CACHE *) mymalloc(sizeof(*cp));
+    cp->name = mystrdup(dbname);
+    cp->cache_flags = 0;
+    cp->user_flags = 0;
+    cp->db = dict;
+    cp->saved_curr_key = 0;
+    cp->saved_curr_val = 0;
+    cp->exp_interval = 0;
+    cp->exp_validator = 0;
+    cp->exp_context = 0;
+    cp->retained = 0;
+    cp->dropped = 0;
+    cp->log_delay = DC_DEF_LOG_DELAY;
+    cp->upd_log_stamp = cp->get_log_stamp =
+	cp->del_log_stamp = cp->seq_log_stamp = 0;
+
+    return (cp);
+}
+
+/* dict_cache_close - close cache file */
+
+void    dict_cache_close(DICT_CACHE *cp)
+{
+
+    /*
+     * Destroy the DICT_CACHE object.
+     */
+    dict_cache_control(cp, DICT_CACHE_CTL_INTERVAL, 0, DICT_CACHE_CTL_END);
+    myfree(cp->name);
+    dict_close(cp->db);
+    if (cp->saved_curr_key)
+	myfree(cp->saved_curr_key);
+    if (cp->saved_curr_val)
+	myfree(cp->saved_curr_val);
+    myfree((void *) cp);
+}
+
+/* dict_cache_name - get the cache name */
+
+const char *dict_cache_name(DICT_CACHE *cp)
+{
+
+    /*
+     * This is used for verbose logging or warning messages, so the cost of
+     * call is only made where needed (well sort off - code that does not
+     * execute still presents overhead for the processor pipeline, processor
+     * cache, etc).
+     */
+    return (cp->name);
+}
+
+ /*
+  * Test driver with support for interleaved access. First, enter a number of
+  * requests to look up, update or delete a sequence of cache entries, then
+  * interleave those sequences with the "run" command.
+  */
+#ifdef TEST
+#include <msg_vstream.h>
+#include <vstring_vstream.h>
+#include <argv.h>
+#include <stringops.h>
+
+#define DELIMS	" "
+#define USAGE	"\n\tTo manage settings:" \
+		"\n\tverbose <level> (verbosity level)" \
+		"\n\telapsed <level> (0=don't show elapsed time)" \
+		"\n\tlmdb_map_size <limit> (initial LMDB size limit)" \
+		"\n\tcache <type>:<name> (switch to named database)" \
+		"\n\tstatus (show map size, cache, pending requests)" \
+		"\n\n\tTo manage pending requests:" \
+		"\n\treset (discard pending requests)" \
+		"\n\trun (execute pending requests in interleaved order)" \
+		"\n\n\tTo add a pending request:" \
+		"\n\tquery <key-suffix> <count> (negative to reverse order)" \
+		"\n\tupdate <key-suffix> <count> (negative to reverse order)" \
+		"\n\tdelete <key-suffix> <count> (negative to reverse order)" \
+		"\n\tpurge <key-suffix>" \
+		"\n\tcount <key-suffix>"
+
+ /*
+  * For realism, open the cache with the same flags as postscreen(8) and
+  * verify(8).
+  */
+#define DICT_CACHE_OPEN_FLAGS (DICT_FLAG_DUP_REPLACE | DICT_FLAG_SYNC_UPDATE | \
+	DICT_FLAG_OPEN_LOCK)
+
+ /*
+  * Storage for one request to access a sequence of cache entries.
+  */
+typedef struct DICT_CACHE_SREQ {
+    int     flags;			/* per-request: reverse, purge */
+    char   *cmd;			/* command for status report */
+    void    (*action) (struct DICT_CACHE_SREQ *, DICT_CACHE *, VSTRING *);
+    char   *suffix;			/* key suffix */
+    int     done;			/* progress indicator */
+    int     todo;			/* number of entries to process */
+    int     first_next;			/* first/next */
+} DICT_CACHE_SREQ;
+
+#define DICT_CACHE_SREQ_FLAG_PURGE	(1<<1)	/* purge instead of count */
+#define DICT_CACHE_SREQ_FLAG_REVERSE	(1<<2)	/* reverse instead of forward */
+
+#define DICT_CACHE_SREQ_LIMIT		10
+
+ /*
+  * All test requests combined.
+  */
+typedef struct DICT_CACHE_TEST {
+    int     flags;			/* exclusion flags */
+    int     size;			/* allocated slots */
+    int     used;			/* used slots */
+    DICT_CACHE_SREQ job_list[1];	/* actually, a bunch */
+} DICT_CACHE_TEST;
+
+#define DICT_CACHE_TEST_FLAG_ITER	(1<<0)	/* count or purge */
+
+#define STR(x)	vstring_str(x)
+
+int     show_elapsed = 1;		/* show elapsed time */
+
+#ifdef HAS_LMDB
+extern size_t dict_lmdb_map_size;	/* LMDB-specific */
+
+#endif
+
+/* usage - command-line usage message */
+
+static NORETURN usage(const char *progname)
+{
+    msg_fatal("usage: %s (no argument)", progname);
+}
+
+/* make_tagged_key - make tagged search key */
+
+static void make_tagged_key(VSTRING *bp, DICT_CACHE_SREQ *cp)
+{
+    if (cp->done < 0)
+	msg_panic("make_tagged_key: bad done count: %d", cp->done);
+    if (cp->todo < 1)
+	msg_panic("make_tagged_key: bad todo count: %d", cp->todo);
+    vstring_sprintf(bp, "%d-%s",
+		    (cp->flags & DICT_CACHE_SREQ_FLAG_REVERSE) ?
+		    cp->todo - cp->done - 1 : cp->done, cp->suffix);
+}
+
+/* create_requests - create request list */
+
+static DICT_CACHE_TEST *create_requests(int count)
+{
+    DICT_CACHE_TEST *tp;
+    DICT_CACHE_SREQ *cp;
+
+    tp = (DICT_CACHE_TEST *) mymalloc(sizeof(DICT_CACHE_TEST) +
+				      (count - 1) *sizeof(DICT_CACHE_SREQ));
+    tp->flags = 0;
+    tp->size = count;
+    tp->used = 0;
+    for (cp = tp->job_list; cp < tp->job_list + count; cp++) {
+	cp->flags = 0;
+	cp->cmd = 0;
+	cp->action = 0;
+	cp->suffix = 0;
+	cp->todo = 0;
+	cp->first_next = DICT_SEQ_FUN_FIRST;
+    }
+    return (tp);
+}
+
+/* reset_requests - reset request list */
+
+static void reset_requests(DICT_CACHE_TEST *tp)
+{
+    DICT_CACHE_SREQ *cp;
+
+    tp->flags = 0;
+    tp->used = 0;
+    for (cp = tp->job_list; cp < tp->job_list + tp->size; cp++) {
+	cp->flags = 0;
+	if (cp->cmd) {
+	    myfree(cp->cmd);
+	    cp->cmd = 0;
+	}
+	cp->action = 0;
+	if (cp->suffix) {
+	    myfree(cp->suffix);
+	    cp->suffix = 0;
+	}
+	cp->todo = 0;
+	cp->first_next = DICT_SEQ_FUN_FIRST;
+    }
+}
+
+/* free_requests - destroy request list */
+
+static void free_requests(DICT_CACHE_TEST *tp)
+{
+    reset_requests(tp);
+    myfree((void *) tp);
+}
+
+/* run_requests - execute pending requests in interleaved order */
+
+static void run_requests(DICT_CACHE_TEST *tp, DICT_CACHE *dp, VSTRING *bp)
+{
+    DICT_CACHE_SREQ *cp;
+    int     todo;
+    struct timeval start;
+    struct timeval finish;
+    struct timeval elapsed;
+
+    if (dp == 0) {
+	msg_warn("no cache");
+	return;
+    }
+    GETTIMEOFDAY(&start);
+    do {
+	todo = 0;
+	for (cp = tp->job_list; cp < tp->job_list + tp->used; cp++) {
+	    if (cp->done < cp->todo) {
+		todo = 1;
+		cp->action(cp, dp, bp);
+	    }
+	}
+    } while (todo);
+    GETTIMEOFDAY(&finish);
+    timersub(&finish, &start, &elapsed);
+    if (show_elapsed)
+	vstream_printf("Elapsed: %g\n",
+		       elapsed.tv_sec + elapsed.tv_usec / 1000000.0);
+
+    reset_requests(tp);
+}
+
+/* show_status - show settings and pending requests */
+
+static void show_status(DICT_CACHE_TEST *tp, DICT_CACHE *dp)
+{
+    DICT_CACHE_SREQ *cp;
+
+#ifdef HAS_LMDB
+    vstream_printf("lmdb_map_size\t%ld\n", (long) dict_lmdb_map_size);
+#endif
+    vstream_printf("cache\t%s\n", dp ? dp->name : "(none)");
+
+    if (tp->used == 0)
+	vstream_printf("No pending requests\n");
+    else
+	vstream_printf("%s\t%s\t%s\t%s\t%s\t%s\n",
+		     "cmd", "dir", "suffix", "count", "done", "first/next");
+
+    for (cp = tp->job_list; cp < tp->job_list + tp->used; cp++)
+	if (cp->todo > 0)
+	    vstream_printf("%s\t%s\t%s\t%d\t%d\t%d\n",
+			   cp->cmd,
+			   (cp->flags & DICT_CACHE_SREQ_FLAG_REVERSE) ?
+			   "reverse" : "forward",
+			   cp->suffix ? cp->suffix : "(null)", cp->todo,
+			   cp->done, cp->first_next);
+}
+
+/* query_action - lookup cache entry */
+
+static void query_action(DICT_CACHE_SREQ *cp, DICT_CACHE *dp, VSTRING *bp)
+{
+    const char *lookup;
+
+    make_tagged_key(bp, cp);
+    if ((lookup = dict_cache_lookup(dp, STR(bp))) == 0) {
+	if (dp->error)
+	    msg_warn("query_action: query failed: %s: %m", STR(bp));
+	else
+	    msg_warn("query_action: query failed: %s", STR(bp));
+    } else if (strcmp(STR(bp), lookup) != 0) {
+	msg_warn("lookup result \"%s\" differs from key \"%s\"",
+		 lookup, STR(bp));
+    }
+    cp->done += 1;
+}
+
+/* update_action - update cache entry */
+
+static void update_action(DICT_CACHE_SREQ *cp, DICT_CACHE *dp, VSTRING *bp)
+{
+    make_tagged_key(bp, cp);
+    if (dict_cache_update(dp, STR(bp), STR(bp)) != 0) {
+	if (dp->error)
+	    msg_warn("update_action: update failed: %s: %m", STR(bp));
+	else
+	    msg_warn("update_action: update failed: %s", STR(bp));
+    }
+    cp->done += 1;
+}
+
+/* delete_action - delete cache entry */
+
+static void delete_action(DICT_CACHE_SREQ *cp, DICT_CACHE *dp, VSTRING *bp)
+{
+    make_tagged_key(bp, cp);
+    if (dict_cache_delete(dp, STR(bp)) != 0) {
+	if (dp->error)
+	    msg_warn("delete_action: delete failed: %s: %m", STR(bp));
+	else
+	    msg_warn("delete_action: delete failed: %s", STR(bp));
+    }
+    cp->done += 1;
+}
+
+/* iter_action - iterate over cache and act on entries with given suffix */
+
+static void iter_action(DICT_CACHE_SREQ *cp, DICT_CACHE *dp, VSTRING *bp)
+{
+    const char *cache_key;
+    const char *cache_val;
+    const char *what;
+    const char *suffix;
+
+    if (dict_cache_sequence(dp, cp->first_next, &cache_key, &cache_val) == 0) {
+	if (strcmp(cache_key, cache_val) != 0)
+	    msg_warn("value \"%s\" differs from key \"%s\"",
+		     cache_val, cache_key);
+	suffix = cache_key + strspn(cache_key, "0123456789");
+	if (suffix[0] == '-' && strcmp(suffix + 1, cp->suffix) == 0) {
+	    cp->done += 1;
+	    cp->todo = cp->done + 1;		/* XXX */
+	    if ((cp->flags & DICT_CACHE_SREQ_FLAG_PURGE)
+		&& dict_cache_delete(dp, cache_key) != 0) {
+		if (dp->error)
+		    msg_warn("purge_action: delete failed: %s: %m", STR(bp));
+		else
+		    msg_warn("purge_action: delete failed: %s", STR(bp));
+	    }
+	}
+	cp->first_next = DICT_SEQ_FUN_NEXT;
+    } else {
+	what = (cp->flags & DICT_CACHE_SREQ_FLAG_PURGE) ? "purge" : "count";
+	if (dp->error)
+	    msg_warn("%s error after %d: %m", what, cp->done);
+	else
+	    vstream_printf("suffix=%s %s=%d\n", cp->suffix, what, cp->done);
+	cp->todo = 0;
+    }
+}
+
+ /*
+  * Table-driven support.
+  */
+typedef struct DICT_CACHE_SREQ_INFO {
+    const char *name;
+    int     argc;
+    void    (*action) (DICT_CACHE_SREQ *, DICT_CACHE *, VSTRING *);
+    int     test_flags;
+    int     req_flags;
+} DICT_CACHE_SREQ_INFO;
+
+static DICT_CACHE_SREQ_INFO req_info[] = {
+    {"query", 3, query_action},
+    {"update", 3, update_action},
+    {"delete", 3, delete_action},
+    {"count", 2, iter_action, DICT_CACHE_TEST_FLAG_ITER},
+    {"purge", 2, iter_action, DICT_CACHE_TEST_FLAG_ITER, DICT_CACHE_SREQ_FLAG_PURGE},
+    0,
+};
+
+/* add_request - add a request to the list */
+
+static void add_request(DICT_CACHE_TEST *tp, ARGV *argv)
+{
+    DICT_CACHE_SREQ_INFO *rp;
+    DICT_CACHE_SREQ *cp;
+    int     req_flags;
+    int     count;
+    char   *cmd = argv->argv[0];
+    char   *suffix = (argv->argc > 1 ? argv->argv[1] : 0);
+    char   *todo = (argv->argc > 2 ? argv->argv[2] : "1");	/* XXX */
+
+    if (tp->used >= tp->size) {
+	msg_warn("%s: request list is full", cmd);
+	return;
+    }
+    for (rp = req_info; /* See below */ ; rp++) {
+	if (rp->name == 0) {
+	    vstream_printf("usage: %s\n", USAGE);
+	    return;
+	}
+	if (strcmp(rp->name, argv->argv[0]) == 0
+	    && rp->argc == argv->argc)
+	    break;
+    }
+    req_flags = rp->req_flags;
+    if (todo[0] == '-') {
+	req_flags |= DICT_CACHE_SREQ_FLAG_REVERSE;
+	todo += 1;
+    }
+    if (!alldig(todo) || (count = atoi(todo)) == 0) {
+	msg_warn("%s: bad count: %s", cmd, todo);
+	return;
+    }
+    if (tp->flags & rp->test_flags) {
+	msg_warn("%s: command conflicts with other command", cmd);
+	return;
+    }
+    tp->flags |= rp->test_flags;
+    cp = tp->job_list + tp->used;
+    cp->cmd = mystrdup(cmd);
+    cp->action = rp->action;
+    if (suffix)
+	cp->suffix = mystrdup(suffix);
+    cp->done = 0;
+    cp->flags = req_flags;
+    cp->todo = count;
+    tp->used += 1;
+}
+
+/* main - main program */
+
+int     main(int argc, char **argv)
+{
+    DICT_CACHE_TEST *test_job;
+    VSTRING *inbuf = vstring_alloc(100);
+    char   *bufp;
+    ARGV   *args;
+    DICT_CACHE *cache = 0;
+    int     stdin_is_tty;
+
+    msg_vstream_init(argv[0], VSTREAM_ERR);
+    if (argc != 1)
+	usage(argv[0]);
+
+
+    test_job = create_requests(DICT_CACHE_SREQ_LIMIT);
+
+    stdin_is_tty = isatty(0);
+
+    for (;;) {
+	if (stdin_is_tty) {
+	    vstream_printf("> ");
+	    vstream_fflush(VSTREAM_OUT);
+	}
+	if (vstring_fgets_nonl(inbuf, VSTREAM_IN) == 0)
+	    break;
+	bufp = vstring_str(inbuf);
+	if (!stdin_is_tty) {
+	    vstream_printf("> %s\n", bufp);
+	    vstream_fflush(VSTREAM_OUT);
+	}
+	if (*bufp == '#')
+	    continue;
+	args = argv_split(bufp, DELIMS);
+	if (argc == 0) {
+	    vstream_printf("usage: %s\n", USAGE);
+	    vstream_fflush(VSTREAM_OUT);
+	    continue;
+	}
+	if (strcmp(args->argv[0], "verbose") == 0 && args->argc == 2) {
+	    msg_verbose = atoi(args->argv[1]);
+	} else if (strcmp(args->argv[0], "elapsed") == 0 && args->argc == 2) {
+	    show_elapsed = atoi(args->argv[1]);
+#ifdef HAS_LMDB
+	} else if (strcmp(args->argv[0], "lmdb_map_size") == 0 && args->argc == 2) {
+	    dict_lmdb_map_size = atol(args->argv[1]);
+#endif
+	} else if (strcmp(args->argv[0], "cache") == 0 && args->argc == 2) {
+	    if (cache)
+		dict_cache_close(cache);
+	    cache = dict_cache_open(args->argv[1], O_CREAT | O_RDWR,
+				    DICT_CACHE_OPEN_FLAGS);
+	} else if (strcmp(args->argv[0], "reset") == 0 && args->argc == 1) {
+	    reset_requests(test_job);
+	} else if (strcmp(args->argv[0], "run") == 0 && args->argc == 1) {
+	    run_requests(test_job, cache, inbuf);
+	} else if (strcmp(args->argv[0], "status") == 0 && args->argc == 1) {
+	    show_status(test_job, cache);
+	} else {
+	    add_request(test_job, args);
+	}
+	vstream_fflush(VSTREAM_OUT);
+	argv_free(args);
+    }
+
+    vstring_free(inbuf);
+    free_requests(test_job);
+    if (cache)
+	dict_cache_close(cache);
+    return (0);
+}
+
+#endif