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diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionContextConsumer.java b/src/main/java/com/google/devtools/build/lib/actions/ActionContextConsumer.java
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+// 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.devtools.build.lib.actions.Executor.ActionContext;
+
+import java.util.Map;
+
+/**
+ * An object describing that actions require a particular implementation of an
+ * {@link ActionContext}.
+ *
+ * <p>This is expected to be implemented by modules that also implement actions which need these
+ * contexts. Other modules will provide implementations for various action contexts by implementing
+ * {@link ActionContextProvider}.
+ *
+ * <p>Example: a module requires {@code SpawnActionContext} to do its job, and it creates
+ * actions with the mnemonic <code>C++</code>. Then the {@link #getSpawnActionContexts} method of
+ * this module would return a map with the key <code>"C++"</code> in it.
+ *
+ * <p>The module can either decide for itself which implementation is needed and make the value
+ * associated with this key a constant or defer that decision to the user, for example, by
+ * providing a command line option and setting the value in the map based on that.
+ *
+ * <p>Other modules are free to provide different implementations of {@code SpawnActionContext}.
+ * This can be used, for example, to implement sandboxed or distributed execution of
+ * {@code SpawnAction}s in different ways, while giving the user control over how exactly they
+ * are executed.
+ */
+public interface ActionContextConsumer {
+  /**
+   * Returns a map from spawn action mnemonics created by this module to the name of the
+   * implementation of {@code SpawnActionContext} that the module wants to use for executing
+   * it.
+   *
+   * <p>If a spawn action is executed whose mnemonic maps to the empty string or is not
+   * present in the map at all, the choice of the implementation is left to Blaze.
+   */
+  public Map<String, String> getSpawnActionContexts();
+
+  /**
+   * Returns a map from action context class to the implementation required by the module.
+   *
+   * <p>If the implementation name is the empty string, the choice is left to Blaze.
+   */
+  public Map<Class<? extends ActionContext>, String> getActionContexts();
+}