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// 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.actions;
import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
import javax.annotation.Nullable;
/**
* An interface for an {@link Action}, containing only side-effect-free query methods for
* information needed during both action analysis and execution.
*
* <p>The split between {@link Action} and {@link ActionExecutionMetadata} is somewhat arbitrary,
* other than that all methods with side effects must belong to the former.
*/
public interface ActionExecutionMetadata extends ActionAnalysisMetadata {
/**
* If this executable can supply verbose information, returns a string that can be used as a
* progress message while this executable is running. A return value of {@code null} indicates no
* message should be reported.
*/
@Nullable
String getProgressMessage();
/**
* Returns a human-readable description of the inputs to {@link #getKey(ActionKeyContext)}. Used
* in the output from '--explain', and in error messages for '--check_up_to_date' and
* '--check_tests_up_to_date'. May return null, meaning no extra information is available.
*
* <p>If the return value is non-null, for consistency it should be a multiline message of the
* form:
*
* <pre>
* <var>Summary</var>
* <var>Fieldname</var>: <var>value</var>
* <var>Fieldname</var>: <var>value</var>
* ...
* </pre>
*
* where each line after the first one is intended two spaces, and where any fields that might
* contain newlines or other funny characters are escaped using {@link
* com.google.devtools.build.lib.shell.ShellUtils#shellEscape}. For example:
*
* <pre>
* Compiling foo.cc
* Command: /usr/bin/gcc
* Argument: '-c'
* Argument: foo.cc
* Argument: '-o'
* Argument: foo.o
* </pre>
*/
@Nullable
String describeKey();
/**
* Get the {@link RunfilesSupplier} providing runfiles needed by this action.
*/
RunfilesSupplier getRunfilesSupplier();
/**
* Returns true iff the getInputs set is known to be complete.
*
* <p>For most Actions, this always returns true, but in some cases (e.g. C++ compilation), inputs
* are dynamically discovered from the previous execution of the Action, and so before the initial
* execution, this method will return false in those cases.
*
* <p>Any builder <em>must</em> unconditionally execute an Action for which this method returns
* false, regardless of all other inferences made by its dependency analysis. In addition, all
* prerequisites mentioned in the (possibly incomplete) value returned by getInputs must also be
* built first, as usual.
*/
@ThreadSafe
boolean inputsDiscovered();
/** Returns true iff {@link #inputsDiscovered()} may ever return false. */
@ThreadSafe
boolean discoversInputs();
/**
* Returns true if the action may create output artifacts whose contents aren't generated by this
* action, and also, this action does not consume its input artifacts' contents.
*
* <p>This is rarely true. Symlink actions are an example where this is true: their outputs'
* contents are equal to their inputs' contents, and a symlink action does not consume its inputs'
* contents.
*
* <p>This property is relevant for action rewinding and top-level output fetching.
*/
default boolean mayInsensitivelyPropagateInputs() {
return false;
}
}