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Stricter rate limit policies #84

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Aug 9, 2024
Merged

Stricter rate limit policies #84

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54 changes: 31 additions & 23 deletions code/src/main/java/com/codeforces/commons/rate/RateUtil.java
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,9 @@
public class RateUtil {
private static final Logger logger = Logger.getLogger(RateUtil.class);

private static final ConcurrentMap<String, SimplePair<Long, Integer>> maxRatePerMinuteByScope = new ConcurrentHashMap<>();
private static final ConcurrentMap<String, SimplePair<Long, Integer>> maxRatePerIntervalByScope
= new ConcurrentHashMap<>();

private static final ConcurrentMap<String, ConcurrentMap<String, Data>> datas = new ConcurrentHashMap<>();
private static final AtomicLong dataCount = new AtomicLong();
private static final AtomicLong counter = new AtomicLong();
Expand All @@ -22,15 +24,16 @@ private RateUtil() {
}

public static void setRestriction(String scope, long intervalMillis, int maxRatePerIntervalMillis) {
maxRatePerMinuteByScope.put(scope, new SimplePair<>(intervalMillis, maxRatePerIntervalMillis));
maxRatePerIntervalByScope.put(scope, new SimplePair<>(intervalMillis, maxRatePerIntervalMillis));
}

public static boolean addEvent(String scope, String session) {
clear();

SimplePair<Long, Integer> restriction = maxRatePerMinuteByScope.get(scope);
SimplePair<Long, Integer> restriction = maxRatePerIntervalByScope.get(scope);
if (restriction == null) {
throw new IllegalStateException("No restriction for the scope '" + scope + "', use #setRestriction(scope, maxRatePerMinute).");
throw new IllegalStateException("No restriction for the scope '" + scope
+ "', use #setRestriction(scope, maxRatePerInterval).");
}

ConcurrentMap<String, Data> scopeDatas = datas.compute(scope, (s, stringQueueConcurrentMap) -> {
Expand All @@ -42,13 +45,12 @@ public static boolean addEvent(String scope, String session) {
});

@SuppressWarnings("ConstantConditions") final Data data = scopeDatas.compute(session, (k, v) -> v == null
? new Data(4, restriction.getFirst(), restriction.getSecond()) : v);
? new Data(3, restriction.getFirst(), restriction.getSecond()) : v);

//noinspection SynchronizationOnLocalVariableOrMethodParameter
synchronized (data) {
boolean add = data.add();
boolean add = data.add(scope, session);
if (!add) {
logger.info("Too many events, RateUtil#addEvent returns false [scope=" + scope + ", session=" + session + "].");
logger.info("Rate limit exceeded, RateUtil#addEvent returns false [scope=" + scope + ", session=" + session + "].");
}
return add;
}
Expand Down Expand Up @@ -83,14 +85,15 @@ private static void clear() {
}
}

logger.warn("RateUtil#clear done [size: " + previousSize + " -> " + (previousSize - removeSize) + " " + (-removeSize) + "].");
logger.warn("RateUtil#clear done [size: previousSize=" + previousSize
+ " -> currentSize=" + (previousSize - removeSize) + ", removedSize=" + removeSize + "].");
}
}

private static final class Data {
private final int depth;
private final long intervalMills;
private final long maxRatePerMinute;
private final long maxRatePerInterval;
private final Queue<Long>[] queues;

private Data(int depth, long intervalMills, int maxRatePerIntervalMillis) {
Expand All @@ -101,19 +104,20 @@ private Data(int depth, long intervalMills, int maxRatePerIntervalMillis) {

this.depth = depth;
this.intervalMills = intervalMills;
this.maxRatePerMinute = maxRatePerIntervalMillis;
this.maxRatePerInterval = maxRatePerIntervalMillis;

//noinspection unchecked
queues = new Queue[depth];
for (int i = 0; i < depth; i++) {
queues[i] = new LinkedList<>();
}
}

private boolean add() {
private boolean add(String scope, String session) {
long currentTimeMillis = System.currentTimeMillis();
adjust(currentTimeMillis);

if (isProper()) {
if (isProper(scope, session)) {
queues[0].add(currentTimeMillis);
return true;
} else {
Expand All @@ -125,11 +129,13 @@ private void adjust(long currentTimeMillis) {
for (int i = depth - 1; i >= 0; i--) {
Queue<Long> queue = queues[i];
while (!queue.isEmpty() && queue.peek() < currentTimeMillis - (1L << i) * intervalMills) {
long elem = queue.poll();
for (int j = i + 1; j < depth; j++) {
if (elem >= currentTimeMillis - (1L << j) * intervalMills) {
queues[j].add(elem);
break;
Long elem = queue.poll();
if (elem != null) {
for (int j = i + 1; j < depth; j++) {
if (elem >= currentTimeMillis - (1L << j) * intervalMills) {
queues[j].add(elem);
break;
}
}
}
}
Expand All @@ -145,12 +151,14 @@ private boolean isEmpty() {
return true;
}

private boolean isProper() {
long sum = 0;
long lim = maxRatePerMinute << (depth - 1);
private boolean isProper(String scope, String session) {
for (int i = 0; i < depth; i++) {
sum += queues[i].size();
if (sum >= lim) {
long lim = Math.round(maxRatePerInterval * Math.pow(1.5, depth - i - 1)) << i;
if (queues[i].size() > lim) {
logger.info("Queue #" + i + " has size " + queues[i].size() + " exceeds limit " + lim
+ " [maxRatePerInterval=" + maxRatePerInterval
+ ", scope=" + scope
+ ", session=" + session + "].");
return false;
}
}
Expand Down
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