GHashTables, oh boy oh boy

LICENSE.md

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+This code is copyright Evan Klitkze, 2009 <evan@eklitzke.org>
+
+This code is currently licensed under the terms of the GPL, version 3. You can
+find the full text of that license online at
+[gnu.org](http://www.gnu.org/licenses/gpl-3.0.txt).

Makefile

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+test_counter: test_counter.c counter.c
+	gcc -o test_counter test_counter.c $(pkg-config glib-2.0 --cflags --libs)

README.md

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+Scribble
+========
+Collect status, build high performance components. 'Nuff said.

counter.c

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+/* This uses hash tables all over the place, which isn't optimal.
+ */
+
+#include <glib.h>
+
+/* Create a new counter. This is really just a hash table. */
+GHashTable* new_counter()
+{
+	GHashTable *ht;
+	ht = g_hash_table_new(g_str_hash, g_str_equal);
+	return ht;
+}
+
+/* This increments a key in for ht[major][minor] */
+void incr_counter(GHashTable *ht, char *major, char *minor)
+{
+	GHashTable *sub;
+	gchar *major_cpy, *minor_cpy;
+	guint *val;
+
+	sub = g_hash_table_lookup(ht, major);
+	if (sub == NULL) {
+		major_cpy = g_strdup(major);
+		sub = g_hash_table_new(g_str_hash, g_str_equal);
+		g_hash_table_insert(ht, major_cpy, sub);
+	}
+
+	val = g_hash_table_lookup(sub, minor);
+	if (val == NULL) {
+		minor_cpy = g_strdup(minor);
+		val = g_slice_alloc0(sizeof(guint));
+		g_hash_table_insert(sub, minor_cpy, val);
+	}
+	(*val)++;
+}
+
+void free_counter(GHashTable *ht)
+{
+	GHashTableIter iter_i, iter_j;
+	gpointer key_i, value_i, key_j, value_j;
+
+	g_hash_table_iter_init(&iter_i, ht);
+	while (g_hash_table_iter_next(&iter_i, &key_i, &value_i)) {
+		g_hash_table_iter_remove(&iter_i);
+		g_free(key_i);
+
+		g_hash_table_iter_init(&iter_j, value_i);
+		while (g_hash_table_iter_next(&iter_j, &key_j, &value_j)) {
+			g_hash_table_iter_remove(&iter_j);
+			g_free(key_j);
+			g_slice_free(guint, value_j);
+		}
+		g_hash_table_destroy(value_i);
+	}
+}
+
+guint lookup_counter(GHashTable *ht, char *major, char *minor)
+{
+	GHashTable *sub;
+	guint *val;
+
+	sub = g_hash_table_lookup(ht, major);
+	if (sub == NULL)
+		return 0;
+
+	val = g_hash_table_lookup(sub, minor);
+	if (val == NULL)
+		return 0;
+	return *val;
+}

test_counter.c

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+#include <glib.h>
+#include "counter.c"
+#include <stdio.h>
+
+int main()
+{
+	GHashTable *ht = new_counter();
+	incr_counter(ht, "foo", "bar");
+	incr_counter(ht, "foo", "baz");
+	incr_counter(ht, "foo", "bar");
+	printf("foo.bar = %d\n", lookup_counter(ht, "foo", "bar"));
+	printf("foo.baz = %d\n", lookup_counter(ht, "foo", "baz"));
+	printf("foo.bad = %d\n", lookup_counter(ht, "foo", "bad"));
+	free_counter(ht);
+	return 0;
+}