Extract MountMap to a top-level class.

--
Change-Id: I26cf10accaa6f62014c65f41637a36fbeab42b0a
Reviewed-on: https://github.com/bazelbuild/bazel/pull/465
MOS_MIGRATED_REVID=103529462

src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedStrategy.java

diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedStrategy.java b/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedStrategy.java
index 8de4dcc..8ce2dca 100644
--- a/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedStrategy.java
+++ b/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedStrategy.java
@@ -16,7 +16,6 @@
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
 import com.google.common.base.Predicates;
-import com.google.common.collect.ForwardingMap;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.io.Files;
 import com.google.devtools.build.lib.Constants;
@@ -47,7 +46,6 @@
 import java.io.File;
 import java.io.IOException;
 import java.nio.charset.Charset;
-import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -72,39 +70,6 @@
   private final UUID uuid = UUID.randomUUID();
   private final AtomicInteger execCounter = new AtomicInteger();
 
-  /**
-   * A map that throws an exception when trying to replace a key (i.e. once a key gets a value,
-   * any additional attempt of putting a value on the same key will throw an exception).
-   */
-  static class MountMap<K, V> extends ForwardingMap<K, V> {
-    final LinkedHashMap<K, V> delegate = new LinkedHashMap<>();
-
-    @Override
-    protected Map<K, V> delegate() {
-      return delegate;
-    }
-
-    @Override
-    public V put(K key, V value) {
-      V previousValue = get(key);
-      if (previousValue == null) {
-        return super.put(key, value);
-      } else if (previousValue.equals(value)) {
-        return value;
-      } else {
-        throw new IllegalArgumentException(
-            String.format("Cannot mount both '%s' and '%s' onto '%s'", previousValue, value, key));
-      }
-    }
-
-    @Override
-    public void putAll(Map<? extends K, ? extends V> map) {
-      for (Entry<? extends K, ? extends V> entry : map.entrySet()) {
-        put(entry.getKey(), entry.getValue());
-      }
-    }
-  }
-
   public LinuxSandboxedStrategy(
       Map<String, String> clientEnv,
       BlazeDirectories blazeDirs,

src/main/java/com/google/devtools/build/lib/sandbox/MountMap.java

diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/MountMap.java b/src/main/java/com/google/devtools/build/lib/sandbox/MountMap.java
new file mode 100644
index 0000000..f9043e3
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/sandbox/MountMap.java
@@ -0,0 +1,52 @@
+// Copyright 2015 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.sandbox;
+
+import com.google.common.collect.ForwardingMap;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+/**
+ * A map that throws an exception when trying to replace a key (i.e. once a key gets a value,
+ * any additional attempt of putting a value on the same key will throw an exception).
+ */
+final class MountMap<K, V> extends ForwardingMap<K, V> {
+  final LinkedHashMap<K, V> delegate = new LinkedHashMap<>();
+
+  @Override
+  protected Map<K, V> delegate() {
+    return delegate;
+  }
+
+  @Override
+  public V put(K key, V value) {
+    V previousValue = get(key);
+    if (previousValue == null) {
+      return super.put(key, value);
+    } else if (previousValue.equals(value)) {
+      return value;
+    } else {
+      throw new IllegalArgumentException(
+          String.format("Cannot mount both '%s' and '%s' onto '%s'", previousValue, value, key));
+    }
+  }
+
+  @Override
+  public void putAll(Map<? extends K, ? extends V> map) {
+    for (Entry<? extends K, ? extends V> entry : map.entrySet()) {
+      put(entry.getKey(), entry.getValue());
+    }
+  }
+}

src/test/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedStrategyTest.java

diff --git a/src/test/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedStrategyTest.java b/src/test/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedStrategyTest.java
index 584c1e3..adfd699 100644
--- a/src/test/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedStrategyTest.java
+++ b/src/test/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedStrategyTest.java
@@ -19,7 +19,6 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
-import com.google.devtools.build.lib.sandbox.LinuxSandboxedStrategy.MountMap;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;