1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
|
// Copyright 2014 The Bazel Authors. All rights reserved.
//
// Licensed 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 com.google.devtools.build.lib.analysis;
/**
* This marker interface must be extended by every interface that represents
* rolled-up data about the transitive closure of a configured target.
*
* TransitiveInfoProviders need to be serializable, and for that reason they must conform to
* the following restrictions:
*
* <ul>
* <li>The provider interface must directly extend {@code TransitiveInfoProvider}.
* <li>Every method must return immutable data.</li>
* <li>Every method must return the same object if called multiple times with the same
* arguments.</li>
* <li>Overloading a method name multiple times is forbidden.</li>
* <li>The return type of a method must satisfy one of the following conditions:
* <ul>
* <li>It must be from the set of {String, Integer, int, Boolean, bool, Label, PathFragment,
* Artifact}, OR</li>
* <li>it must be an ImmutableList/List/Collection/Iterable of T, where T is either
* one of the types above with a default serializer or T implements ValueSerializer), OR</li>
* <li>it must be serializable (TBD)</li>
* </ul>
* <li>If the method takes arguments, it must declare a custom serializer (TBD).</li>
* </ul>
*
* <p>Some typical uses of this interface are:
* <ul>
* <li>The set of Python source files in the transitive closure of this rule
* <li>The set of declared C++ header files in the transitive closure
* <li>The files that need to be built when the target is mentioned on the command line
* </ul>
*
* <p>Note that if implemented naively, this would result in the memory requirements
* being O(n^2): in a long dependency chain, if every target adds one single artifact, storing the
* transitive closures of every rule would take 1+2+3+...+n-1+n = O(n^2) memory.
*
* <p>In order to avoid this, we introduce the concept of nested sets, {@link com.google.devtools
* .build.lib.collect.nestedset.NestedSet}. A nested set is an immutable
* data structure that can contain direct members and other nested sets (recursively). Nested sets
* are iterable and can be flattened into ordered sets, where the order depends on which
* implementation of NestedSet you pick.
*
* @see TransitiveInfoCollection
*/
public interface TransitiveInfoProvider {
}
|
