1 /*
2 * *************************************************************************************************************************************************************
3 *
4 * TheseFoolishThings: Miscellaneous utilities
5 * http://tidalwave.it/projects/thesefoolishthings
6 *
7 * Copyright (C) 2009 - 2025 by Tidalwave s.a.s. (http://tidalwave.it)
8 *
9 * *************************************************************************************************************************************************************
10 *
11 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
12 * You may obtain a copy of the License at
13 *
14 * http://www.apache.org/licenses/LICENSE-2.0
15 *
16 * 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
17 * CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
18 *
19 * *************************************************************************************************************************************************************
20 *
21 * git clone https://bitbucket.org/tidalwave/thesefoolishthings-src
22 * git clone https://github.com/tidalwave-it/thesefoolishthings-src
23 *
24 * *************************************************************************************************************************************************************
25 */
26 package it.tidalwave.role.impl;
27
28 import javax.annotation.Nonnull;
29 import java.util.Collections;
30 import java.util.List;
31 import java.util.concurrent.CopyOnWriteArrayList;
32 import it.tidalwave.util.ContextManager;
33 import it.tidalwave.util.Task;
34 import lombok.extern.slf4j.Slf4j;
35 import static it.tidalwave.util.ShortNames.*;
36
37 /***************************************************************************************************************************************************************
38 *
39 * A facility that takes a snapshot of the contexts that are current at creation time and make them available later.
40 *
41 * @author Fabrizio Giudici
42 *
43 **************************************************************************************************************************************************************/
44 @Slf4j
45 public class ContextSnapshot
46 {
47 private final ContextManager contextManager = ContextManager.getInstance();
48
49 // TODO: should be weak references? Should a context be alive as soon as all the objects created with it are
50 // alive?
51 private final List<Object> contexts = Collections.unmodifiableList(contextManager.getContexts());
52
53 /***********************************************************************************************************************************************************
54 * Creates a new instance and samples the currently available contexts.
55 *
56 * @param owner the owner
57 **********************************************************************************************************************************************************/
58 public ContextSnapshot (@Nonnull final Object owner)
59 {
60 if (log.isTraceEnabled())
61 {
62 log.trace(">>>> contexts for {} at construction time: {}", shortId(owner), shortIds(contexts));
63 }
64 }
65
66 /***********************************************************************************************************************************************************
67 * Returns the previously sampled contexts.
68 *
69 * @return the contexts
70 **********************************************************************************************************************************************************/
71 @Nonnull
72 public List<Object> getContexts()
73 {
74 return new CopyOnWriteArrayList<>(contexts);
75 }
76
77 /***********************************************************************************************************************************************************
78 * Runs a {@link Task} associated with the sampled contexts.
79 *
80 * @param <V> the type of the result value
81 * @param <T> the type of the exception
82 * @param task the task
83 * @return the value produced by the task
84 * @throws T the exception(s) thrown by the task
85 **********************************************************************************************************************************************************/
86 public <V, T extends Throwable> V runWithContexts (@Nonnull final Task<V, T> task)
87 throws T
88 {
89 return contextManager.runWithContexts(contexts, task);
90 }
91
92 /***********************************************************************************************************************************************************
93 * {@inheritDoc}
94 **********************************************************************************************************************************************************/
95 @Override @Nonnull
96 public String toString()
97 {
98 return String.format("ContextSnapshot%s", shortIds(contexts));
99 }
100 }