Update from Google.
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MOE_MIGRATED_REVID=85702957
diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionMetadata.java b/src/main/java/com/google/devtools/build/lib/actions/ActionMetadata.java
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index 0000000..3569f07
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionMetadata.java
@@ -0,0 +1,217 @@
+// Copyright 2014 Google Inc. 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.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
+
+import javax.annotation.Nullable;
+
+/**
+ * Side-effect free query methods for information about an {@link Action}.
+ *
+ * <p>This method is intended for use in situations when the intention is to pass around information
+ * about an action without allowing actual execution of the action.
+ *
+ * <p>The split between {@link Action} and {@link ActionMetadata} is somewhat arbitrary, other than
+ * that all methods with side effects must belong to the former.
+ */
+public interface ActionMetadata {
+ /**
+ * 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
+ public String getProgressMessage();
+
+ /**
+ * Returns the owner of this executable if this executable can supply verbose information. This is
+ * typically the rule that constructed it; see ActionOwner class comment for details. Returns
+ * {@code null} if no owner can be determined.
+ *
+ * <p>If this executable does not supply verbose information, this function may throw an
+ * IllegalStateException.
+ */
+ public ActionOwner getOwner();
+
+ /**
+ * Returns a mnemonic (string constant) for this kind of action; written into
+ * the master log so that the appropriate parser can be invoked for the output
+ * of the action. Effectively a public method as the value is used by the
+ * extra_action feature to match actions.
+ */
+ String getMnemonic();
+
+ /**
+ * Returns a pretty string representation of this action, suitable for use in
+ * progress messages or error messages.
+ */
+ String prettyPrint();
+
+ /**
+ * Returns a string that can be used to describe the execution strategy.
+ * For example, "local".
+ *
+ * May return null if the action chooses to update its strategy
+ * locality "manually", via ActionLocalityMessage.
+ *
+ * @param executor the application-specific value passed to the
+ * executor parameter of the top-level call to
+ * Builder.buildArtifacts().
+ */
+ public String describeStrategy(Executor executor);
+
+ /**
+ * 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 inputsKnown() 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 inputsKnown();
+
+ /**
+ * Returns true iff inputsKnown() may ever return false.
+ */
+ @ThreadSafe
+ boolean discoversInputs();
+
+ /**
+ * Returns the input Artifacts that this Action depends upon. May be empty.
+ *
+ * <p>For subclasses overriding getInputs(), if getInputs() could return different values in the
+ * lifetime of an object, {@link #getInputCount()} must also be overridden.
+ *
+ * <p>During execution, the {@link Iterable} returned by {@code getInputs} <em>must not</em> be
+ * concurrently modified before the value is fully read in {@code JavaDistributorDriver#exec} (via
+ * the {@code Iterable<ActionInput>} argument there). Violating this would require somewhat
+ * pathological behavior by the {@link Action}, since it would have to modify its inputs, as a
+ * list, say, without reassigning them. This should never happen with any Action subclassing
+ * AbstractAction, since AbstractAction's implementation of getInputs() returns an immutable
+ * iterable.
+ */
+ Iterable<Artifact> getInputs();
+
+ /**
+ * Returns the number of input Artifacts that this Action depends upon.
+ *
+ * <p>Must be consistent with {@link #getInputs()}.
+ */
+ int getInputCount();
+
+ /**
+ * Returns the (unordered, immutable) set of output Artifacts that
+ * this action generates. (It would not make sense for this to be empty.)
+ */
+ ImmutableSet<Artifact> getOutputs();
+
+ /**
+ * Returns the "primary" input of this action, if applicable.
+ *
+ * <p>For example, a C++ compile action would return the .cc file which is being compiled,
+ * irrespective of the other inputs.
+ *
+ * <p>May return null.
+ */
+ Artifact getPrimaryInput();
+
+ /**
+ * Returns the "primary" output of this action.
+ *
+ * <p>For example, the linked library would be the primary output of a LinkAction.
+ *
+ * <p>Never returns null.
+ */
+ Artifact getPrimaryOutput();
+
+ /**
+ * Returns an iterable of input Artifacts that MUST exist prior to executing an action. In other
+ * words, in case when action is scheduled for execution, builder will ensure that all artifacts
+ * returned by this method are present in the filesystem (artifact.getPath().exists() is true) or
+ * action execution will be aborted with an error that input file does not exist. While in
+ * majority of cases this method will return all action inputs, for some actions (e.g.
+ * CppCompileAction) it can return a subset of inputs because that not all action inputs might be
+ * mandatory for action execution to succeed (e.g. header files retrieved from *.d file from the
+ * previous build).
+ */
+ Iterable<Artifact> getMandatoryInputs();
+
+ /**
+ * <p>Returns a string encoding all of the significant behaviour of this
+ * Action that might affect the output. The general contract of
+ * <code>getKey</code> is this: if the work to be performed by the
+ * execution of this action changes, the key must change. </p>
+ *
+ * <p>As a corollary, the build system is free to omit the execution of an
+ * Action <code>a1</code> if (a) at some time in the past, it has already
+ * executed an Action <code>a0</code> with the same key as
+ * <code>a1</code>, and (b) the names and contents of the input files listed
+ * by <code>a1.getInputs()</code> are identical to the names and contents of
+ * the files listed by <code>a0.getInputs()</code>. </p>
+ *
+ * <p>Examples of changes that should affect the key are:
+ * <ul>
+ * <li>Changes to the BUILD file that materially affect the rule which gave
+ * rise to this Action.</li>
+ *
+ * <li>Changes to the command-line options, environment, or other global
+ * configuration resources which affect the behaviour of this kind of Action
+ * (other than changes to the names of the input/output files, which are
+ * handled externally).</li>
+ *
+ * <li>An upgrade to the build tools which changes the program logic of this
+ * kind of Action (typically this is achieved by incorporating a UUID into
+ * the key, which is changed each time the program logic of this action
+ * changes).</li>
+ *
+ * </ul></p>
+ */
+ String getKey();
+
+ /**
+ * Returns a human-readable description of the inputs to {@link #getKey()}.
+ * 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();
+}
