389-ds-base/ldap/servers/plugins/retrocl/retrocl_trim.c

/** BEGIN COPYRIGHT BLOCK
 * Copyright (C) 2001 Sun Microsystems, Inc. Used by permission.
 * Copyright (C) 2005 Red Hat, Inc.
 * All rights reserved.
 *
 * License: GPL (version 3 or any later version).
 * See LICENSE for details. 
 * END COPYRIGHT BLOCK **/

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif



#include "retrocl.h"

typedef struct _trim_status {
    time_t		ts_c_max_age;		/* Constraint  - max age of a changelog entry */
    time_t		ts_s_last_trim;		/* Status - last time we trimmed */
    int			ts_s_initialized;	/* Status - non-zero if initialized */
    int			ts_s_trimming;		/* non-zero if trimming in progress */
    PRLock		*ts_s_trim_mutex;	/* protects ts_s_trimming */
} trim_status;
static trim_status ts = {0L, 0L, 0, 0, NULL};
static int trim_interval = DEFAULT_CHANGELOGDB_TRIM_INTERVAL; /* in second */

/*
 * All standard changeLogEntry attributes (initialized in get_cleattrs)
 */
static const char *cleattrs[ 10 ] = { NULL, NULL, NULL, NULL, NULL, NULL,
				      NULL, NULL, NULL };

static int retrocl_trimming = 0;
static Slapi_Eq_Context retrocl_trim_ctx = NULL;

/*
 * Function: get_cleattrs
 *
 * Returns: an array of pointers to attribute names.
 *
 * Arguments: None.
 *
 * Description: Initializes, if necessary, and returns an array of char *s
 *              with attribute names used for retrieving changeLogEntry
 *              entries from the directory.
 */
static const char **get_cleattrs(void)
{
    if ( cleattrs[ 0 ] == NULL ) {
        cleattrs[ 0 ] = attr_objectclass;
        cleattrs[ 1 ] = attr_changenumber;
        cleattrs[ 2 ] = attr_targetdn;
        cleattrs[ 3 ] = attr_changetype;
        cleattrs[ 4 ] = attr_newrdn;
        cleattrs[ 5 ] = attr_deleteoldrdn;
        cleattrs[ 6 ] = attr_changes;
        cleattrs[ 7 ] = attr_newsuperior;
        cleattrs[ 8 ] = attr_changetime;
        cleattrs[ 9 ] = NULL;
    }
    return cleattrs;
}

/*
 * Function: delete_changerecord
 *
 * Returns: LDAP_ error code
 * 
 * Arguments: the number of the change to delete
 *
 * Description:
 *
 */

static int
delete_changerecord( changeNumber cnum )
{
    Slapi_PBlock *pb;
    char	*dnbuf;
    int		delrc;

    dnbuf = slapi_ch_smprintf("%s=%ld, %s", attr_changenumber, cnum, 
                              RETROCL_CHANGELOG_DN);
    pb = slapi_pblock_new ();
    slapi_delete_internal_set_pb ( pb, dnbuf, NULL /*controls*/, NULL /* uniqueid */,
                                   g_plg_identity[PLUGIN_RETROCL], 0 /* actions */ );
    slapi_delete_internal_pb (pb);
    slapi_pblock_get( pb, SLAPI_PLUGIN_INTOP_RESULT, &delrc );
    slapi_pblock_destroy( pb );
    
    if ( delrc != LDAP_SUCCESS ) {
        slapi_log_error( SLAPI_LOG_FATAL, RETROCL_PLUGIN_NAME, 
                         "delete_changerecord: could not delete change record %lu (rc: %d)\n",
                         cnum, delrc );
    } else {
        slapi_log_error( SLAPI_LOG_PLUGIN, RETROCL_PLUGIN_NAME,
                         "delete_changerecord: deleted changelog entry \"%s\"\n", dnbuf);
    }
    slapi_ch_free((void **) &dnbuf );
    return delrc;
}

/*
 * Function: handle_getchangetime_result
 * Arguments: op - pointer to Operation struct for this operation
 *            err - error code returned from search
 * Returns: nothing
 * Description: result handler for get_changetime().  Sets the crt_err
 *              field of the cnum_result_t struct to the error returned
 *              from the backend.
 */
static void
handle_getchangetime_result( int err, void *callback_data )
{
    cnum_result_t *crt = callback_data;

    if ( crt == NULL ) {
	slapi_log_error( SLAPI_LOG_FATAL, RETROCL_PLUGIN_NAME,
		"handle_getchangetime_result: callback_data NULL\n" );
    } else {
	crt->crt_err = err;
    }
}

/*
 * Function: handle_getchangetime_search
 * Arguments: op - pointer to Operation struct for this operation
 *            e - entry returned by backend
 * Returns: 0 in all cases
 * Description: Search result operation handler for get_changetime().
 *              Sets fields in the cnum_result_t struct pointed to by
 *              op->o_handler_data.
 */
static int
handle_getchangetime_search( Slapi_Entry *e, void *callback_data)
{
    cnum_result_t *crt = callback_data;
    int rc;
    Slapi_Attr	*attr;

    if (crt == NULL) {
        slapi_log_error(SLAPI_LOG_FATAL, RETROCL_PLUGIN_NAME,
                "handle_getchangetime_search: op->o_handler_data NULL\n");
    } else if (crt->crt_nentries > 0) {
        /* only return the first entry, I guess */
        slapi_log_error(SLAPI_LOG_FATAL, RETROCL_PLUGIN_NAME,
                "handle_getchangetime_search: multiple entries returned\n");
    } else {
        crt->crt_nentries++;
        crt->crt_time = 0;

        if (NULL != e) {
            Slapi_Value *sval = NULL;
            const struct berval *val = NULL;
            rc = slapi_entry_attr_find(e, attr_changetime, &attr);
            /* Bug 624442: Logic checking for lack of timestamp was
               reversed. */
            if (0 != rc || slapi_attr_first_value(attr, &sval) == -1 ||
                    (val = slapi_value_get_berval(sval)) == NULL ||
                    NULL == val->bv_val) {
                crt->crt_time = 0;
            } else {
                crt->crt_time = parse_localTime(val->bv_val);
            }
        }
    }

    return 0;
}


/*
 * Function: get_changetime
 * Arguments: cnum - number of change record to retrieve
 * Returns: Taking the attr_changetime of the 'cnum' entry,
 * it converts it into time_t (parse_localTime) and returns this time value.
 * It returns 0 in the following cases:
 *  - changerecord entry has not attr_changetime
 *  - attr_changetime attribute has no value
 *  - attr_changetime attribute value is empty
 * 
 * Description: Retrieve attr_changetime ("changetime") from a changerecord whose number is "cnum".
 */
static time_t get_changetime( changeNumber cnum, int *err ) 
{
    cnum_result_t crt, *crtp = &crt;
    char fstr[ 16 + CNUMSTR_LEN + 2 ];
    Slapi_PBlock *pb;

    if (cnum == 0UL) {
        if (err != NULL) {
            *err = LDAP_PARAM_ERROR;
        }
        return 0;
    }
    crtp->crt_nentries = crtp->crt_err = 0;
    crtp->crt_time = 0;
    PR_snprintf(fstr, sizeof (fstr), "%s=%ld", attr_changenumber, cnum);

    pb = slapi_pblock_new();
    slapi_search_internal_set_pb(pb, RETROCL_CHANGELOG_DN,
            LDAP_SCOPE_SUBTREE, fstr,
            (char **) get_cleattrs(), /* cast const */
            0 /* attrsonly */,
            NULL /* controls */, NULL /* uniqueid */,
            g_plg_identity[PLUGIN_RETROCL],
            0 /* actions */);

    slapi_search_internal_callback_pb(pb, crtp,
            handle_getchangetime_result,
            handle_getchangetime_search, NULL);
    if (err != NULL) {
        *err = crtp->crt_err;
    }

    slapi_pblock_destroy(pb);

    return ( crtp->crt_time);
}

/*
 * Function: trim_changelog
 *
 * Arguments: none
 *
 * Returns: 0 on success, -1 on failure
 *
 * Description: Trims the changelog, according to the constraints
 * described by the ts structure.
 */
static int trim_changelog(void)
{
    int			rc = 0, ldrc, done;
    time_t		now;
    changeNumber	first_in_log = 0, last_in_log = 0;
    int			num_deleted = 0;
    int me,lt;
    

    now = current_time();

    PR_Lock( ts.ts_s_trim_mutex );
    me = ts.ts_c_max_age;
    lt = ts.ts_s_last_trim;
    PR_Unlock( ts.ts_s_trim_mutex );

    if ( now - lt >= trim_interval ) {

	/*
	 * Trim the changelog.  Read sequentially through all the
	 * entries, deleting any which do not meet the criteria
	 * described in the ts structure.
	 */
	done = 0;

	while ( !done && retrocl_trimming == 1 ) {
	    int		did_delete;

	    did_delete = 0;
	    first_in_log = retrocl_get_first_changenumber();
	    if ( 0UL == first_in_log ) {
	        slapi_log_error( SLAPI_LOG_PLUGIN, RETROCL_PLUGIN_NAME, 
				 "trim_changelog: no changelog records "
				 "to trim\n" );
		/* Bail out - we can't do any useful work */
		break;
	    }

	    last_in_log = retrocl_get_last_changenumber();
	    if ( last_in_log == first_in_log ) {
		/* Always leave at least one entry in the change log */
		break;
	    }
	    if ( me > 0L ) {
            time_t change_time = get_changetime(first_in_log, &ldrc);
            if (change_time) {
                if ((change_time + me) < now) {
                    retrocl_set_first_changenumber(first_in_log + 1);
                    ldrc = delete_changerecord(first_in_log);
                    num_deleted++;
                    did_delete = 1;
                }
            } else {
                /* What to do if there's no timestamp? Just delete it. */
                retrocl_set_first_changenumber(first_in_log + 1);
                ldrc = delete_changerecord(first_in_log);
                num_deleted++;
                did_delete = 1;
             }   
	    }
	    if ( !did_delete ) {
		done = 1;
	    }
	}
    } else {
       LDAPDebug(LDAP_DEBUG_PLUGIN, "not yet time to trim: %ld < (%d+%d)\n",
                 now, lt, trim_interval);
    }
    PR_Lock( ts.ts_s_trim_mutex );
    ts.ts_s_trimming = 0;
    ts.ts_s_last_trim = now;
    PR_Unlock( ts.ts_s_trim_mutex );
    if ( num_deleted > 0 ) {
	slapi_log_error( SLAPI_LOG_PLUGIN, RETROCL_PLUGIN_NAME, 
			 "trim_changelog: removed %d change records\n",
			 num_deleted );
    }
    return rc;
}

static int retrocl_active_threads;

/*
 * Function: changelog_trim_thread_fn
 *
 * Returns: nothing
 * 
 * Arguments: none
 *
 * Description: the thread creation callback.  retrocl_active_threads is 
 * provided for debugging purposes.
 *
 */
 
static void
changelog_trim_thread_fn( void *arg )
{
    PR_AtomicIncrement(&retrocl_active_threads);
    trim_changelog();
    PR_AtomicDecrement(&retrocl_active_threads);
}



/*
 * Function: retrocl_housekeeping
 * Arguments: cur_time - the current time
 * Returns: nothing
 * Description: Determines if it is time to trim the changelog database,
 *              and if so, determines if the changelog database needs to
 *              be trimmed.  If so, a thread is started which will trim
 *              the database.  
 */

void retrocl_housekeeping ( time_t cur_time, void *noarg )
{
    int			ldrc;

    if (retrocl_be_changelog == NULL) {
        LDAPDebug0Args(LDAP_DEBUG_TRACE,"not housekeeping if no cl be\n");
	return;
    }

    if ( !ts.ts_s_initialized ) {
	slapi_log_error( SLAPI_LOG_FATAL, RETROCL_PLUGIN_NAME, "changelog_housekeeping called before "
		"trimming constraints set\n" );
	return;
    }

    PR_Lock( ts.ts_s_trim_mutex );
    if ( !ts.ts_s_trimming ) {
	int	must_trim = 0;
	/* See if we need to trim */
	/* Has enough time elapsed since our last check? */
	if ( cur_time - ts.ts_s_last_trim >= (ts.ts_c_max_age) ) {
		/* Is the first entry too old? */
		time_t first_time;
		/*
		 * good we could avoid going to the database to retrieve
		 * this time information if we cached the last value we'd read.
		 * But a client might have deleted it over protocol.
		 */
		first_time = retrocl_getchangetime( SLAPI_SEQ_FIRST, &ldrc );
		LDAPDebug(LDAP_DEBUG_PLUGIN,
			  "cltrim: ldrc=%d, first_time=%ld, cur_time=%ld\n",
			  ldrc,first_time,cur_time);
		if ( LDAP_SUCCESS == ldrc && first_time > (time_t) 0L &&
		     first_time + ts.ts_c_max_age < cur_time ) {
		    must_trim = 1;
		}
	}
	if ( must_trim ) {
	    LDAPDebug0Args(LDAP_DEBUG_TRACE,"changelog about to create thread\n");
	    /* Start a thread to trim the changelog */
	    ts.ts_s_trimming = 1;
	    if ( PR_CreateThread( PR_USER_THREAD,
		    changelog_trim_thread_fn, NULL,
		    PR_PRIORITY_NORMAL, PR_GLOBAL_THREAD, PR_UNJOINABLE_THREAD,
		    RETROCL_DLL_DEFAULT_THREAD_STACKSIZE ) == NULL ) {
		slapi_log_error( SLAPI_LOG_FATAL, RETROCL_PLUGIN_NAME, "unable to create changelog trimming thread\n" );
	    }
	} else {
	    LDAPDebug0Args(LDAP_DEBUG_PLUGIN,
		      "changelog does not need to be trimmed\n");
	}
    }
    PR_Unlock( ts.ts_s_trim_mutex );
}

/*
 * Function: retrocl_init_trimming
 *
 * Returns: none, exits on fatal error
 * 
 * Arguments: none
 *
 * Description: called during startup
 *
 */

void retrocl_init_trimming (void)
{
    const char *cl_maxage;
    time_t ageval = 0; /* Don't trim, by default */
    const char *cl_trim_interval;
    
    cl_maxage = retrocl_get_config_str(CONFIG_CHANGELOG_MAXAGE_ATTRIBUTE);
    if (cl_maxage) {
        if (slapi_is_duration_valid(cl_maxage)) {
            ageval = slapi_parse_duration(cl_maxage);
            slapi_ch_free_string((char **)&cl_maxage);
        } else {
            slapi_log_error(SLAPI_LOG_FATAL, RETROCL_PLUGIN_NAME, 
                        "retrocl_init_trimming: ignoring invalid %s value %s; "
                        "not trimming retro changelog.\n",
                        CONFIG_CHANGELOG_MAXAGE_ATTRIBUTE, cl_maxage);
            slapi_ch_free_string((char **)&cl_maxage);
            return;
        }
    }
    
    cl_trim_interval = retrocl_get_config_str(CONFIG_CHANGELOG_TRIM_INTERVAL);
    if (cl_trim_interval) {
      trim_interval = strtol(cl_trim_interval, (char **)NULL, 10);
      if (0 == trim_interval) {
        slapi_log_error(SLAPI_LOG_FATAL, RETROCL_PLUGIN_NAME, 
                        "retrocl_init_trimming: ignoring invalid %s value %s; "
                        "resetting the default %d\n",
                        CONFIG_CHANGELOG_TRIM_INTERVAL, cl_trim_interval,
                        DEFAULT_CHANGELOGDB_TRIM_INTERVAL);
        trim_interval = DEFAULT_CHANGELOGDB_TRIM_INTERVAL;
      }
      slapi_ch_free_string((char **)&cl_trim_interval);
    }
    
    ts.ts_c_max_age = ageval;
    ts.ts_s_last_trim = (time_t) 0L;
    ts.ts_s_trimming = 0;
    if (( ts.ts_s_trim_mutex = PR_NewLock()) == NULL ) {
      slapi_log_error( SLAPI_LOG_FATAL, RETROCL_PLUGIN_NAME, "set_changelog_trim_constraints: "
                       "cannot create new lock.\n" );
      exit( 1 );
    }
    ts.ts_s_initialized = 1;
    retrocl_trimming = 1;
    
    retrocl_trim_ctx = slapi_eq_repeat(retrocl_housekeeping,
                                       NULL, (time_t)0,
                                       /* in milliseconds */
                                       trim_interval * 1000);
}

/*
 * Function: retrocl_stop_trimming
 *
 * Returns: none
 * 
 * Arguments: none
 *
 * Description: called when server is shutting down to ensure trimming stops
 * eventually.
 *
 */

void retrocl_stop_trimming(void)
{
    retrocl_trimming = 0;
    if (retrocl_trim_ctx) {
      slapi_eq_cancel(retrocl_trim_ctx);
      retrocl_trim_ctx = NULL;
    }
}