Adds CodecScanner to help automate building a codec registry.

Scan takes 1-2s.

PiperOrigin-RevId: 183881368

1 files changed, 42 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/serialization/CodecScanner.java b/src/main/java/com/google/devtools/build/lib/skyframe/serialization/CodecScanner.java
new file mode 100644
index 0000000000..7536c6df1b
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/serialization/CodecScanner.java
@@ -0,0 +1,42 @@
+// Copyright 2018 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.skyframe.serialization;
+
+import com.google.common.reflect.ClassPath;
+import com.google.common.reflect.ClassPath.ClassInfo;
+import java.io.IOException;
+import java.util.stream.Stream;
+
+/** Scans the classpath to find codec instances. */
+public class CodecScanner {
+
+  /**
+   * Returns a stream of likely codec implementations.
+   *
+   * <p>Caller should do additional checks as this method only performs string matching.
+   *
+   * @param packagePrefix emits only classes in packages having this prefix
+   */
+  public static Stream<Class<?>> scanCodecs(String packagePrefix) throws IOException {
+    return ClassPath.from(ClassLoader.getSystemClassLoader())
+        .getResources()
+        .stream()
+        .filter(r -> r instanceof ClassInfo)
+        .map(r -> (ClassInfo) r)
+        .filter(c -> c.getPackageName().startsWith(packagePrefix))
+        .filter(c -> c.getSimpleName().endsWith("Codec"))
+        .map(c -> c.load());
+  }
+}