1 files changed, 114 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/server/ServerResponse.java b/src/main/java/com/google/devtools/build/lib/server/ServerResponse.java
new file mode 100644
index 0000000000..e5ab9300f7
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+++ b/src/main/java/com/google/devtools/build/lib/server/ServerResponse.java
@@ -0,0 +1,114 @@
+// 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.server;
+
+import com.google.common.base.Preconditions;
+
+import java.io.ByteArrayOutputStream;
+import java.io.UnsupportedEncodingException;
+
+/**
+ * This class models a response from the {@link RPCServer}. This is a
+ * tuple of an error message and the exit status. The encoding of the response
+ * is extremely simple {@link #toString()}:
+ *
+ * <ul><li>Iff a message is present, the wire format is
+ *         <pre>message + '\n' + exit code as string + '\n'</pre>
+ *     </li>
+ *     <li>Otherwise it's just the exit code as string + '\n'</li>
+ * </ul>
+ */
+final class ServerResponse {
+
+  /**
+   * Parses an input string into a {@link ServerResponse} object.
+   */
+  public static ServerResponse parseFrom(String input) {
+    if (input.charAt(input.length() - 1) != '\n') {
+      String msg = "Response must end with newline (" + input + ")";
+      throw new IllegalArgumentException(msg);
+    }
+    int newlineAt = input.lastIndexOf('\n', input.length() - 2);
+
+    final String exitStatusString;
+    final String errorMessage;
+    if (newlineAt == -1) {
+      errorMessage = "";
+      exitStatusString = input.substring(0, input.length() - 1);
+    } else {
+      errorMessage = input.substring(0, newlineAt);
+      exitStatusString = input.substring(newlineAt + 1, input.length() - 1);
+    }
+
+    return new ServerResponse(errorMessage, Integer.parseInt(exitStatusString));
+  }
+
+  /**
+   * Parses {@code bytes} into a {@link ServerResponse} instance, assuming
+   * Latin 1 encoding.
+   */
+  public static ServerResponse parseFrom(byte[] bytes) {
+    try {
+      return parseFrom(new String(bytes, "ISO-8859-1"));
+    } catch (UnsupportedEncodingException e) {
+      throw new AssertionError(e); // Latin 1 is everywhere.
+    }
+  }
+
+  /**
+   * Parses {@code bytes} into a {@link ServerResponse} instance, assuming
+   * Latin 1 encoding.
+   */
+  public static ServerResponse parseFrom(ByteArrayOutputStream bytes) {
+    return parseFrom(bytes.toByteArray());
+  }
+
+  private final String errorMessage;
+  private final int exitStatus;
+
+  /**
+   * Construct a new instance given an error message and an exit status.
+   */
+  public ServerResponse(String errorMessage, int exitStatus) {
+    Preconditions.checkNotNull(errorMessage);
+    this.errorMessage = errorMessage;
+    this.exitStatus = exitStatus;
+  }
+
+  /**
+   * The wire representation of this response object.
+   */
+  @Override
+  public String toString() {
+    if (errorMessage.length() == 0) {
+      return Integer.toString(exitStatus) + '\n';
+    }
+    return errorMessage + '\n' + Integer.toString(exitStatus) + '\n';
+  }
+
+  @Override
+  public boolean equals(Object other) {
+    if (other == null || !(other instanceof ServerResponse)) return false;
+    ServerResponse otherResponse = (ServerResponse) other;
+    return exitStatus == otherResponse.exitStatus
+        && errorMessage.equals(otherResponse.errorMessage);
+  }
+
+  @Override
+  public int hashCode() {
+    return exitStatus * 31 ^ errorMessage.hashCode();
+  }
+
+}