moved hash sizing code into portmon lib, where it belongs

git-svn-id: https://conky.svn.sourceforge.net/svnroot/conky/trunk/conky@393 7f574dfc-610e-0410-a909-a81674777703

src/conky.c

@@ -259,8 +259,8 @@ int no_buffers;
 static int pad_percents = 0;
 
 #ifdef TCP_PORT_MONITOR
-static int min_port_monitors = 0;		 	/* config item */
+tcp_port_monitor_collection_args_t 	tcp_port_monitor_collection_args;
-static int min_port_monitor_connections = 0;		/* config item */
+tcp_port_monitor_args_t 		tcp_port_monitor_args;
 #endif
 
 /* Text that is shown */
@@ -1826,18 +1826,8 @@ int a = stippled_borders, b = 1;
 	 	/* if the port monitor collection hasn't been created, we must create it */
 	 	if ( !info.p_tcp_port_monitor_collection )
 		{
-			double hash_size, log_base_2;
+			info.p_tcp_port_monitor_collection = 
-
+				create_tcp_port_monitor_collection( &tcp_port_monitor_collection_args );
-			/* calculate hash_size from min_port_monitors */
-			hash_size = (double)min_port_monitors / (double)TCP_MONITOR_HASH_MAX_LOAD_PCT;
-			/* correct hash_size to nearest power of two */
-			log_base_2 = log(hash_size) / log(2);
-			if ( log_base_2 - (int)log_base_2 > 0.001 )
-				log_base_2 = (double)( (int)log_base_2 + 1 );
-			hash_size = pow(2,log_base_2); 
-			/*fprintf(stderr,"collection hash size is %d\n",(int)hash_size);*/
-
-			info.p_tcp_port_monitor_collection = create_tcp_port_monitor_collection( (int)hash_size );
 			if ( !info.p_tcp_port_monitor_collection )
 			{
 				CRIT_ERR("tcp_portmon: unable to create port monitor collection");
@@ -1847,19 +1837,8 @@ int a = stippled_borders, b = 1;
 		/* if a port monitor for this port does not exist, create one and add it to the collection */
 		if ( find_tcp_port_monitor( info.p_tcp_port_monitor_collection, port_begin, port_end ) == NULL )
 		{
-			double hash_size, log_base_2;
-
-			/* calculate hash_size from min_port_monitor_connections */
-			hash_size = (double)min_port_monitor_connections / (double)TCP_CONNECTION_HASH_MAX_LOAD_PCT;
-			/* correct hash_size to nearest power of two */
-			log_base_2 = log(hash_size) / log(2);
-			if ( log_base_2 - (int)log_base_2 > 0.001)
-				log_base_2 = (double)( (int)log_base_2 + 1 );
-			hash_size = pow(2, log_base_2);
-			/*fprintf(stderr,"monitor hash size is %d\n",(int)hash_size);*/
-
 			tcp_port_monitor_t * p_monitor = 
-				create_tcp_port_monitor( port_begin, port_end, (int)hash_size );
+				create_tcp_port_monitor( port_begin, port_end, &tcp_port_monitor_args );
 			if ( !p_monitor )
 			{
 				CRIT_ERR("tcp_portmon: unable to create port monitor");
@@ -4507,8 +4486,8 @@ static void set_default_configurations(void)
 #endif
 
 #ifdef TCP_PORT_MONITOR
-	min_port_monitors = MIN_PORT_MONITORS_DEFAULT;
+	tcp_port_monitor_collection_args.min_port_monitors = MIN_PORT_MONITORS_DEFAULT;
-	min_port_monitor_connections = MIN_PORT_MONITOR_CONNECTIONS_DEFAULT;
+	tcp_port_monitor_args.min_port_monitor_connections = MIN_PORT_MONITOR_CONNECTIONS_DEFAULT;
 #endif
 }
 
@@ -4919,20 +4898,20 @@ else if (strcasecmp(name, a) == 0 || strcasecmp(name, b) == 0)
 		CONF("min_port_monitors") 
 		{
 			if ( !value || 
-			     (sscanf(value, "%d", &min_port_monitors) != 1) || 
+			     (sscanf(value, "%d", &tcp_port_monitor_collection_args.min_port_monitors) != 1) || 
-			     min_port_monitors <= 0 )
+			     tcp_port_monitor_collection_args.min_port_monitors <= 0 )
 			{
-				min_port_monitors = MIN_PORT_MONITORS_DEFAULT;
+				tcp_port_monitor_collection_args.min_port_monitors = MIN_PORT_MONITORS_DEFAULT;
 				CONF_ERR;
 			}
 		}
 		CONF("min_port_monitor_connections") 
 		{
 			if ( !value || 
-			     (sscanf(value, "%d", &min_port_monitor_connections) != 1) 
+			     (sscanf(value, "%d", &tcp_port_monitor_args.min_port_monitor_connections) != 1) 
-			     || min_port_monitor_connections <= 0 )
+			     || tcp_port_monitor_args.min_port_monitor_connections <= 0 )
 			{
-				min_port_monitor_connections = MIN_PORT_MONITOR_CONNECTIONS_DEFAULT;
+				tcp_port_monitor_args.min_port_monitor_connections = MIN_PORT_MONITOR_CONNECTIONS_DEFAULT;
 				CONF_ERR;
 			}
 		}

src/conky.h

@@ -114,7 +114,6 @@ struct mpd_s {
 #endif
 
 #ifdef TCP_PORT_MONITOR
-#include <math.h>
 #include "libtcp-portmon.h"
 #define MIN_PORT_MONITORS_DEFAULT 16
 #define MIN_PORT_MONITOR_CONNECTIONS_DEFAULT 256

src/libtcp-portmon.c

@@ -328,7 +328,7 @@ void maintain_tcp_port_monitor_hash(
 #ifdef HASH_DEBUG
     fprintf(stderr,"--- num vacated is %d, vacated factor is %.3f\n", p_monitor->hash.vacated, vacated_load );
 #endif
-    if ( vacated_load <= TCP_CONNECIION_HASH_MAX_VACATED_PCT )
+    if ( vacated_load <= TCP_CONNECIION_HASH_MAX_VACATED_RATIO )
     {
 	    /* hash is fine and needs no rebalancing */
 	    return;
@@ -371,7 +371,7 @@ void rebuild_tcp_port_monitor_peek_table(
 	return;
 
    /* zero out the peek array */
-   memset( p_monitor->p_peek, 0, TCP_CONNECTION_HASH_SIZE * sizeof(tcp_connection_t *) );
+   memset( p_monitor->p_peek, 0, p_monitor->hash.size * sizeof(tcp_connection_t *) );
 
    for ( p_node=p_monitor->connection_list.p_head; p_node!=NULL; p_node=p_node->p_next, i++ )
    {
@@ -427,7 +427,7 @@ void show_connection_to_tcp_port_monitor(
 	 * connection limit.  Future versions should probably allow the client to set the hash size
 	 * and load limits and/or provide for automatic resizing of hashes. */
 
-	if ( (double)p_monitor->hash.size / (double)p_monitor->hash.positions >= TCP_CONNECTION_HASH_MAX_LOAD_PCT )
+	if ( (double)p_monitor->hash.size / (double)p_monitor->hash.positions >= TCP_CONNECTION_HASH_MAX_LOAD_RATIO )
 	{
 		/* hash exceeds our load limit is now "full" */
 		return;
@@ -498,6 +498,37 @@ void for_each_tcp_port_monitor_in_collection(
   
 }
 
+/* ----------------------------------------------------------------------------------------
+ * Calculate an efficient hash size based on the desired number of elements and load factor.
+ * ---------------------------------------------------------------------------------------- */
+int calc_efficient_hash_size(
+	int                                     min_elements,
+	int					max_hash_size,
+	double                                  max_load_factor
+	)
+{
+   double min_size, hash_size, log_base_2;
+   
+   /* the size of the hash will the smallest power of two such that the minimum number
+      of desired elements does not exceed the maximum load factor. */                 
+   
+   min_size = (double)min_elements / max_load_factor;   /* starting point */
+     
+   /* now adjust size up to nearest power of two */
+   log_base_2 = (double) (int) ( log(min_size) / log(2) ) ;  /* lop off fractional portion of log */
+
+   hash_size = pow(2,log_base_2) >= min_size ? min_size : pow(2,(double)++log_base_2);
+
+   /* respect the maximum */
+   hash_size = hash_size <= max_hash_size ? hash_size : max_hash_size;
+
+   /*
+   fprintf(stderr,"hash size is %d, based on %d min_elements and %.02f max load, %d maximum\n",
+		   (int)hash_size, min_elements, max_load_factor, max_hash_size);
+   */
+
+   return hash_size;
+}
 		
 /* ----------------------------------------------------------------------
  * CLIENT INTERFACE 
@@ -514,7 +545,7 @@ void for_each_tcp_port_monitor_in_collection(
 tcp_port_monitor_t * create_tcp_port_monitor(
 	in_port_t 				port_range_begin, 
 	in_port_t 				port_range_end,
-	int					hash_size
+	tcp_port_monitor_args_t *		p_creation_args
 	)
 {
    tcp_port_monitor_t * p_monitor;
@@ -526,7 +557,11 @@ tcp_port_monitor_t * create_tcp_port_monitor(
 
    /* create the monitor's connection hash */
    if ( hash_create( &p_monitor->hash, 
-			hash_size > 0 ? hash_size : TCP_CONNECTION_HASH_SIZE,
+			p_creation_args && p_creation_args->min_port_monitor_connections > 0 ?
+				calc_efficient_hash_size( p_creation_args->min_port_monitor_connections,
+							  TCP_CONNECTION_HASH_SIZE_MAX,
+							  TCP_CONNECTION_HASH_MAX_LOAD_RATIO ) :
+				TCP_CONNECTION_HASH_SIZE_DEFAULT,
 			&connection_hash_function_1, &connection_hash_function_2,
 			&connection_match_function, NULL ) != 0 ) 
    {
@@ -536,7 +571,7 @@ tcp_port_monitor_t * create_tcp_port_monitor(
    }
 
    /* create the monitor's peek array */
-   if ( (p_monitor->p_peek = (tcp_connection_t **) calloc( TCP_CONNECTION_HASH_SIZE, sizeof(tcp_connection_t *))) == NULL )
+   if ( (p_monitor->p_peek = (tcp_connection_t **) calloc( p_monitor->hash.size, sizeof(tcp_connection_t *))) == NULL )
    {
 	/* we failed to create the peek array, so destroy the monitor completely, again, so we don't leak */
 	destroy_tcp_port_monitor(p_monitor,NULL);
@@ -658,7 +693,7 @@ int peek_tcp_port_monitor(
 
 /* Create a monitor collection.  Do this one first. */
 tcp_port_monitor_collection_t * create_tcp_port_monitor_collection(
-	int					hash_size
+	tcp_port_monitor_collection_args_t * 	p_creation_args
 	)
 {
    tcp_port_monitor_collection_t * p_collection;
@@ -669,7 +704,11 @@ tcp_port_monitor_collection_t * create_tcp_port_monitor_collection(
 
    /* create the collection's monitor hash */
    if ( hash_create( &p_collection->hash, 
-			hash_size > 0 ? hash_size : TCP_MONITOR_HASH_SIZE,
+			p_creation_args && p_creation_args->min_port_monitors > 0 ?
+				calc_efficient_hash_size( p_creation_args->min_port_monitors,
+							  TCP_MONITOR_HASH_SIZE_MAX,
+							  TCP_MONITOR_HASH_MAX_LOAD_RATIO ) :
+				TCP_MONITOR_HASH_SIZE_DEFAULT,
 			&monitor_hash_function_1, &monitor_hash_function_2,
 			&monitor_match_function, NULL ) != 0 )
    {

src/libtcp-portmon.h

@@ -23,6 +23,7 @@
 #ifndef LIBTCP_PORTMON_H
 #define LIBTCP_PORTMON_H
 
+#include <math.h>
 #include <netdb.h>
 #include <netinet/in.h>
 #include <netinet/tcp.h>
@@ -37,7 +38,7 @@
  * Each port monitor contains a connection hash whose contents changes dynamically as the monitor 
  * is presented with connections on each update cycle.   This implementation maintains the health
  * of this hash by enforcing several rules.  First, the hash cannot contain more items than the
- * TCP_CONNECTION_HASH_MAX_LOAD_PCT permits.  For example, a 256 element hash with a max load of 
+ * TCP_CONNECTION_HASH_MAX_LOAD_RATIO permits.  For example, a 256 element hash with a max load of 
  * 0.5 cannot contain more than 128 connections.  Additional connections are ignored by the monitor.
  * The load factor of 0.5 is low enough to keep the hash running at near O(1) performanace at all 
  * times.  As elements are removed from the hash, the hash slots are tagged vacated, as required 
@@ -46,14 +47,15 @@
  * The problem with vacated slots (even though they are reused) is that, as they increase in number,
  * esp. past about 1/4 of all slots, the average number of probes the hash has to perform increases
  * from O(1) on average to O(n) worst case. To keep the hash healthy, we simply rebuild it when the
- * percentage of vacated slots gets too high (above TCP_CONNECTION_HASH_MAX_VACATED_PCT).  Rebuilding
+ * percentage of vacated slots gets too high (above TCP_CONNECTION_HASH_MAX_VACATED_RATIO).  
- * the hash takes O(n) on the number of elements, but it well worth it as it keeps the hash running
+ * Rebuilding the hash takes O(n) on the number of elements, but it well worth it as it keeps the
- * at an average access time of O(1).
+ * hash running at an average access time of O(1).
  * ------------------------------------------------------------------------------------------------*/
 
-#define TCP_CONNECTION_HASH_SIZE 512			/* connection hash size -- must be a power of two */
+#define TCP_CONNECTION_HASH_SIZE_DEFAULT 512		/* connection hash size default -- must be a power of two */
-#define TCP_CONNECTION_HASH_MAX_LOAD_PCT 0.5		/* disallow inserts after this % load is exceeded */
+#define TCP_CONNECTION_HASH_SIZE_MAX 65535            	/* connection hash size maximum -- must be a power of two */
-#define TCP_CONNECIION_HASH_MAX_VACATED_PCT 0.25 	/* rebalance hash after this % of vacated slots is exceeded */ 
+#define TCP_CONNECTION_HASH_MAX_LOAD_RATIO 0.5		/* disallow inserts after this load ratio is exceeded */
+#define TCP_CONNECIION_HASH_MAX_VACATED_RATIO 0.25 	/* rebalance hash after this ratio of vacated slots is exceeded */ 
 #define TCP_CONNECIION_STARTING_AGE 1			/* connection deleted if unseen again after this # of refreshes */
 
 /* ----------------------------------------------------------------------------------------
@@ -66,8 +68,9 @@
  * lookups at O(1).  
  * ----------------------------------------------------------------------------------------*/
 
-#define TCP_MONITOR_HASH_SIZE 32			/* monitor hash size -- must be a power of two */
+#define TCP_MONITOR_HASH_SIZE_DEFAULT 32		/* monitor hash size default -- must be a power of two */
-#define TCP_MONITOR_HASH_MAX_LOAD_PCT 0.5               /* disallow new monitors after this % load is exceeded */
+#define TCP_MONITOR_HASH_SIZE_MAX 512                	/* monitor hash size maximum -- must be a power of two */
+#define TCP_MONITOR_HASH_MAX_LOAD_RATIO 0.5             /* disallow new monitors after this load ratio is exceeded */
 
 /* -------------------------------------------------------------------
  * IMPLEMENTATION INTERFACE
@@ -217,6 +220,14 @@ void for_each_tcp_port_monitor_in_collection(
 	void *					/* p_function_args (for user arguments) */
 	);
 
+/* ----------------------------------------------------------------------------------------
+ * Calculate an efficient hash size based on the desired number of elements and load factor.
+ * ---------------------------------------------------------------------------------------- */
+int calc_efficient_hash_size(
+	int 					/* min_elements, the minimum number of elements to store */,
+	int					/* max_hash_size, the maximum permissible hash size */,
+	double					/* max_load_factor, the fractional load we wish not to exceed, e.g. 0.5 */
+	);
 
 /* ----------------------------------------------------------------------
  * CLIENT INTERFACE 
@@ -224,6 +235,17 @@ void for_each_tcp_port_monitor_in_collection(
  * Clients should call only those functions below this line.
  * ---------------------------------------------------------------------- */
 
+/* struct to hold monitor creation arguments */
+typedef struct _tcp_port_monitor_args_t {
+	int 	min_port_monitor_connections;	/* monitor must support tracking at least this many connections */
+} tcp_port_monitor_args_t;
+
+
+/* struct to hold collection creation arguments */
+typedef struct _tcp_port_monitor_collection_args_t {
+	int	min_port_monitors;		/* collection must support creation of at least this many monitors */
+} tcp_port_monitor_collection_args_t; 
+
 /* ----------------------------------
  * Client operations on port monitors
  * ---------------------------------- */
@@ -233,7 +255,7 @@ void for_each_tcp_port_monitor_in_collection(
 tcp_port_monitor_t * create_tcp_port_monitor(
 	in_port_t 				/* port_range_begin */, 
 	in_port_t 				/* port_range_end */,
-	int					/* hash_size */
+	tcp_port_monitor_args_t *		/* p_creation_args, NULL ok for library defaults */
 	);
 
 /* Clients use this function to get connection data from the indicated port monitor.
@@ -253,7 +275,7 @@ int peek_tcp_port_monitor(
 
 /* Create a monitor collection.  Do this one first. */
 tcp_port_monitor_collection_t * create_tcp_port_monitor_collection(
-	int					 /* hash_size */ 
+	tcp_port_monitor_collection_args_t *	/* p_creation_args, NULL ok for library defaults */
 	);
 
 /* Destroy the monitor collection (and everything it contains).  Do this one last. */

tests/Makefile

@@ -16,7 +16,7 @@ test-hash:		test-hash.o hash.o
 			$(CC) $(CFLAGS) -o $@ test-hash.o hash.o
 
 test-portmon:		test-portmon.o libtcp-portmon.o hash.o
-			$(CC) $(CFLAGS) -o $@ test-portmon.o libtcp-portmon.o hash.o
+			$(CC) $(CFLAGS) -o $@ test-portmon.o libtcp-portmon.o hash.o -lm
 
 test-hash.o:		test-hash.c hash.h
 test-portmon.o:		test-portmon.c libtcp-portmon.h hash.h

tests/test-portmon.c

@@ -25,12 +25,12 @@ int main()
 
    (void) signal(SIGINT,set_terminate);
 
-   if ( (p_collection = create_tcp_port_monitor_collection( 0 )) == NULL) {
+   if ( (p_collection = create_tcp_port_monitor_collection( NULL )) == NULL) {
 	fprintf(stderr,"error: create_tcp_port_monitor_collection()\n");
    	exit(1);
    }
 
-   if ( (p_monitor = create_tcp_port_monitor( 1, 65535, 0 )) == NULL) {
+   if ( (p_monitor = create_tcp_port_monitor( 1, 65535, NULL )) == NULL) {
 	fprintf(stderr,"error: create_tcp_port_monitor()\n");
 	exit(1);
    }