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/*
* Copyright (C) 2008, 2009 Nokia Corporation.
*
* Contact: Marius Vollmer <marius.vollmer@nokia.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* version 2.1 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
*/
using GLib;
namespace ContextProvider {
/**
* SECTION:KeyUsageCounter
* @short_description: A subscription counter for keys.
*
* A data structure which tracks the number of subscriptions for
* keys.
*/
internal class KeyUsageCounter : GLib.Object {
/**
* ContextProviderKeyUsageCounter
*
* A data structure which tracks the number of subscriptions for
* keys.
*/
// The number of subscribers for each key (over all subscriber objects)
internal Gee.HashMap<string, int> subscriber_count_table {get; private set;}
public StringSet subscribed_keys { get; private set; }
public signal void keys_added (StringSet new_keys);
public signal void keys_removed (StringSet keys_removed, StringSet keys_remaining);
/**
* Constructs a new KeyUsageCounter.
*/
public KeyUsageCounter() {
subscribed_keys = new StringSet();
subscriber_count_table = new Gee.HashMap<string, int>(str_hash, str_equal);
}
/**
* @key: a string
* Increases the subscription count of the #key.
*/
public void add (StringSet keys) {
StringSet first_subscribed_keys = new StringSet();
foreach (var key in keys) {
if (subscriber_count_table.contains (key)) {
int old_value = subscriber_count_table.get (key);
subscriber_count_table.set (key, old_value + 1);
if (old_value == 0) {
// This is the first subscribed to the key
first_subscribed_keys.add (key);
}
debug ("Subscriber count of %s is now %d", key, old_value + 1);
}
else { // Key name not present in the key table
subscriber_count_table.set (key, 1);
first_subscribed_keys.add (key);
debug ("Subscriber count of %s is now %d", key, 1);
}
}
if (first_subscribed_keys.size() > 0) {
keys_added (first_subscribed_keys);
}
subscribed_keys = new StringSet.union (subscribed_keys, first_subscribed_keys);
}
/**
* @key: a string
* Decreases the subscription count of the #key.
*/
public void remove (StringSet keys) {
StringSet last_unsubscribed_keys = new StringSet();
foreach (var key in keys) {
if (subscriber_count_table.contains (key)) {
int value = subscriber_count_table.get (key);
if (value >= 1) {
value--;
subscriber_count_table.set (key, value);
}
if (value == 0) {
// The last subscriber for this key unsubscribed
last_unsubscribed_keys.add (key);
}
debug ("Subscriber count of %s is now %d", key, value);
}
else {
// This should not happen
debug ("Error: decreasing the subscriber count of an unknown key.");
}
}
subscribed_keys = new StringSet.difference (subscribed_keys, last_unsubscribed_keys);
if (last_unsubscribed_keys.size() > 0) {
// Signal that some keys are not subscribed to anymore
keys_removed (last_unsubscribed_keys, subscribed_keys);
}
}
/**
* @key: a string
* Returns: The subscription count of the #key.
*/
public int number_of_subscribers (string key) {
if (subscriber_count_table.contains (key)) {
return subscriber_count_table.get (key);
}
return 0;
}
}
}
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