upd: create rate limit for account creation

[gigi.git] / src / org / cacert / gigi / util / RateLimit.java

diff --git a/src/org/cacert/gigi/util/RateLimit.java b/src/org/cacert/gigi/util/RateLimit.java
new file mode 100644 (file)
index 0000000..46098bf
--- /dev/null
+++ b/src/org/cacert/gigi/util/RateLimit.java
@@ -0,0 +1,73 @@
+package org.cacert.gigi.util;
+
+import java.util.HashMap;
+import java.util.TreeSet;
+
+public class RateLimit {
+
+    private class Entry implements Comparable<Entry> {
+
+        long firstAccess;
+
+        int count = 1;
+
+        String feature;
+
+        public Entry(long firstAccess, String feature) {
+            this.firstAccess = firstAccess;
+            this.feature = feature;
+        }
+
+        public void access() {
+            count++;
+        }
+
+        @Override
+        public int compareTo(Entry o) {
+            return feature.compareTo(o.feature);
+        }
+
+        public boolean isExpired() {
+            return firstAccess + time < System.currentTimeMillis();
+        }
+
+    }
+
+    private final int maxcount;
+
+    private final long time;
+
+    TreeSet<Entry> set = new TreeSet<Entry>();
+
+    HashMap<String, Entry> feat = new HashMap<>();
+
+    public RateLimit(int maxcount, long time) {
+        this.maxcount = maxcount;
+        this.time = time;
+    }
+
+    public synchronized boolean isLimitExceeded(String feature) {
+        clean();
+        Entry e = feat.get(feature);
+        if (e == null) {
+            e = new Entry(System.currentTimeMillis(), feature);
+            set.add(e);
+            feat.put(feature, e);
+        } else {
+            e.access();
+        }
+        return e.count > maxcount;
+    }
+
+    private void clean() {
+        while (set.size() > 0) {
+            Entry e = set.last();
+            if (e.isExpired()) {
+                set.remove(e);
+                feat.remove(e.feature);
+            } else {
+                return;
+            }
+        }
+    }
+}