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1   package org.apache.maven.surefire.junitcore.pc;
2   
3   /*
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *     http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  
22  /**
23   * @author Tibor Digana (tibor17)
24   * @since 2.16
25   *
26   * @see Balancer
27   */
28  public class BalancerFactory {
29      private BalancerFactory()
30      {
31      }
32  
33      /**
34       * Infinite permits.
35       */
36      public static Balancer createInfinitePermitsBalancer()
37      {
38          return balancer( 0, false );
39      }
40  
41      /**
42       * Balancer without fairness.
43       * Fairness guarantees the waiting schedulers to wake up in order they acquired a permit.
44       *
45       * @param concurrency number of permits to acquire when maintaining concurrency on tests
46       */
47      public static Balancer createBalancer( int concurrency )
48      {
49          return balancer( concurrency, false );
50      }
51  
52      /**
53       * Balancer with fairness.
54       * Fairness guarantees the waiting schedulers to wake up in order they acquired a permit.
55       *
56       * @param concurrency number of permits to acquire when maintaining concurrency on tests
57       */
58      public static Balancer createBalancerWithFairness( int concurrency )
59      {
60          return balancer( concurrency, true );
61      }
62  
63      private static Balancer balancer( int concurrency, boolean fairness )
64      {
65          boolean shouldBalance = concurrency > 0 && concurrency < Integer.MAX_VALUE;
66          return shouldBalance ? new ThreadResourcesBalancer( concurrency, fairness ) : new NullBalancer();
67      }
68  }