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Subject: array sorting checked in
From: Martin Hunt <hunt@redhat.com>
To: systemtap@sources.redhat.com
Content-Type: text/plain
Organization: Red Hat Inc.
Date: Fri, 23 Sep 2005 08:36:00 -0000
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I checked in several new functions to the runtime.

_stp_map_sort(MAP map, int keynum, int dir)
_stp_map_sortn(MAP map, int n, int keynum, int dir)
_stp_map_printn(MAP map, int n, const char *fmt)

keynum = 0 for value, or > 0 for the key number to sort on.
n = number of elements to print or sort. 0 means entire array.
dir = sorting direction. -1 or 1 

_stp_map_sortn() will scan an array and put the top (or bottom) 'n'
elements at the start of the array.  This is useful when you don't care
about the whole array, just the top values.  

Here's a working  example. (the current language can't pass array
references, therefore the awkward embedded C)

--------------------

global foo, moo

function print_foo (num:long) %{
	_stp_map_printn(global_foo, THIS->num, "%1s is %s");
%}

function print_moo (num:long) %{
	_stp_map_printn(global_moo, THIS->num, "%1d,%2d,%3d,%4d,%5d = %d");
%}

function sort_foo (num:long, key:long, dir:long) %{
	_stp_map_sortn(global_foo, THIS->num, THIS->key, THIS->dir);
%}

function sort_moo (num:long, key:long, dir:long) %{
	_stp_map_sortn(global_moo, THIS->num, THIS->key, THIS->dir);
%}

probe begin
{
	foo["seattle"] = "sleepless"
	foo["new orleans"] = "wet"
	foo["florida"] = "hot"
	foo["texas"] = "red"
	foo["san francisco"] = "wired"
	foo["galveston"] = "scared"
	foo["miami"] = "viced"
	foo["maine"] = "iced"

		
	moo[1,2,3,4,5] = 1000
	moo[1,12,3,1,6] = 1001
	moo[2,2,3,4,5] = 1000
	moo[10,20,30,40,50] = 10000
	moo[8,2,3,4,7] = -1000
	moo[-1,2,4,1,6] = 2001
	moo[0,2,4,0,6] = 1002

	log("sorted by value");
	sort_foo(0,0,-1)
	print_foo(0)

	log("sorted by value (reverse)");
	sort_foo(0,0,1)
	print_foo(0)

	log("sorted by key 1");
	sort_foo(0,1,-1)
	print_foo(0)

	/* reverse the list again */
	sort_foo(0,1,1)

	log("Just the top three. Sorted by key 1");
	sort_foo(3,1,-1)
	print_foo(3)

	print_moo(0)
	log("sorted by value");
	sort_moo(0,0,-1)
	print_moo(0)

	log("sorted by value (reverse)");
	sort_moo(0,0,1)
	print_moo(0)

	log("sorted by key 1");
	sort_moo(0,1,-1)
	print_moo(0)

	exit()
}