content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.beam.runners.core.metrics;
  
  import com.google.auto.value.AutoValue;
  import java.io.Serializable;
  import java.util.Arrays;
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  import org.apache.beam.sdk.metrics.StringSetResult;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.annotations.VisibleForTesting;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableSet;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Data describing the StringSet. The {@link StringSetData} hold a copy of the set from which it was
   * initially created. This should retain enough detail that it can be combined with other {@link
   * StringSetData}.
   *
   * <p>The underlying set is mutable for {@link #addAll} operation, otherwise a copy set will be
   * generated.
   *
   * <p>The summation of all string length for a {@code StringSetData} cannot exceed 1 MB. Further
   * addition of elements are dropped.
   */
  @AutoValue
  public abstract class StringSetData implements Serializable {
    private static final Logger LOG = LoggerFactory.getLogger(StringSetData.class);
    // 1 MB
    @VisibleForTesting static final long STRING_SET_SIZE_LIMIT = 1_000_000L;
  
    public abstract Set<String> stringSet();
  
    public abstract long stringSize();
  
    /** Returns a {@link StringSetData} which is made from an immutable copy of the given set. */
    public static StringSetData create(Set<String> set) {
      if (set.isEmpty()) {
        return empty();
      }
      Set<String> combined = ConcurrentHashMap.newKeySet();
      long stringSize = addUntilCapacity(combined, 0L, set);
      return new AutoValue_StringSetData(combined, stringSize);
    }
  
    /** Returns a {@link StringSetData} which is made from the given set in place. */
    private static StringSetData createInPlace(Set<String> set, long stringSize) {
      return new AutoValue_StringSetData(set, stringSize);
    }
  
    /** Return a {@link EmptyStringSetData#INSTANCE} representing an empty {@link StringSetData}. */
    public static StringSetData empty() {
      return EmptyStringSetData.INSTANCE;
    }
  
    /**
     * Add strings into this {@code StringSetData} and return the result {@code StringSetData}. Reuse
     * the original StringSetData's set. As a result, current StringSetData will become invalid.
     *
     * <p>>Should only be used by {@link StringSetCell#add}.
     */
    public StringSetData addAll(String... strings) {
      Set<String> combined;
      if (this.stringSet() instanceof ConcurrentHashMap.KeySetView) {
        combined = this.stringSet();
      } else {
        combined = ConcurrentHashMap.newKeySet();
        combined.addAll(this.stringSet());
      }
      long stringSize = addUntilCapacity(combined, this.stringSize(), Arrays.asList(strings));
      return StringSetData.createInPlace(combined, stringSize);
    }
  
    /**
     * Combines this {@link StringSetData} with other, both original StringSetData are left intact.
     */
    public StringSetData combine(StringSetData other) {
      if (this.stringSet().isEmpty()) {
        return other;
      } else if (other.stringSet().isEmpty()) {
        return this;
      } else {
        Set<String> combined = ConcurrentHashMap.newKeySet();
        combined.addAll(this.stringSet());
        long stringSize = addUntilCapacity(combined, this.stringSize(), other.stringSet());
        return StringSetData.createInPlace(combined, stringSize);
      }
    }
  
    /**
     * Combines this {@link StringSetData} with others, all original StringSetData are left intact.
     */
    public StringSetData combine(Iterable<StringSetData> others) {
      Set<String> combined = ConcurrentHashMap.newKeySet();
      combined.addAll(this.stringSet());
      long stringSize = this.stringSize();
      for (StringSetData other : others) {
        stringSize = addUntilCapacity(combined, stringSize, other.stringSet());
      }
      return StringSetData.createInPlace(combined, stringSize);
    }
  
    /** Returns a {@link StringSetResult} representing this {@link StringSetData}. */
    public StringSetResult extractResult() {
      return StringSetResult.create(stringSet());
    }
  
    /** Add strings into set until reach capacity. Return the all string size of added set. */
    private static long addUntilCapacity(
        Set<String> combined, long currentSize, Iterable<String> others) {
      if (currentSize > STRING_SET_SIZE_LIMIT) {
        // already at capacity
        return currentSize;
      }
      for (String string : others) {
        if (combined.add(string)) {
          currentSize += string.length();
  
          // check capacity both before insert and after insert one, so the warning only emit once.
          if (currentSize > STRING_SET_SIZE_LIMIT) {
            LOG.warn(
                "StringSet metrics reaches capacity. Further incoming elements won't be recorded."
                    + " Current size: {}, last element size: {}.",
                currentSize,
                string.length());
            break;
          }
        }
      }
      return currentSize;
    }
  
    /** Empty {@link StringSetData}, representing no values reported and is immutable. */
    public static class EmptyStringSetData extends StringSetData {
  
      private static final EmptyStringSetData INSTANCE = new EmptyStringSetData();
  
      private EmptyStringSetData() {}
  
      /** Returns an immutable empty set. */
      @Override
      public Set<String> stringSet() {
        return ImmutableSet.of();
      }
  
      @Override
      public long stringSize() {
        return 0L;
      }
  
      /** Return a {@link StringSetResult#empty()} which is immutable empty set. */
      @Override
      public StringSetResult extractResult() {
        return StringSetResult.empty();
      }
    }
  }
  