HADOOP-19131. Wrapped IO

move the unchecking as default methods in CallableRaisingIOE,
FunctionRaisingIOE etc makes for a clean and flexible design.

some test enhancements.

Change-Id: If25b6d0377bc9e4e8d4a6e689692ddfa96b1c756

Author: steveloughran

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/wrappedio/WrappedStatistics.java

@@ -18,12 +18,10 @@
 
 package org.apache.hadoop.io.wrappedio;
 
-import java.io.IOException;
 import java.io.Serializable;
 import java.io.UncheckedIOException;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.function.Function;
 import javax.annotation.Nullable;
 
 import org.apache.hadoop.classification.InterfaceAudience;
@@ -120,7 +118,7 @@ public static Serializable iostatisticsSnapshot_create() {
    * Create a new {@link IOStatisticsSnapshot} instance.
    * @param source optional source statistics
    * @return an IOStatisticsSnapshot.
-   * @throws ClassCastException if the {@code source}
+   * @throws ClassCastException if the {@code source} is not null and not an IOStatistics instance
    */
   public static Serializable iostatisticsSnapshot_create(@Nullable Object source) {
     return new IOStatisticsSnapshot((IOStatistics) source);
@@ -342,21 +340,18 @@ public static <T> T applyToIOStatisticsSnapshot(
       Serializable source,
       FunctionRaisingIOE<IOStatisticsSnapshot, T> fun) {
 
-    requireIOStatisticsSnapshot(source);
-    try {
-      return fun.apply((IOStatisticsSnapshot) source);
-    } catch (IOException e) {
-      throw new UncheckedIOException(e);
-    }
+    return fun.unchecked(requireIOStatisticsSnapshot(source));
   }
 
   /**
    * Require the parameter to be an instance of {@link IOStatisticsSnapshot}.
-   * @param snapshot class to validate
+   * @param snapshot object to validate
+   * @return cast value
    * @throws IllegalArgumentException if the supplied class is not a snapshot
    */
-  private static void requireIOStatisticsSnapshot(final Serializable snapshot) {
+  private static IOStatisticsSnapshot requireIOStatisticsSnapshot(final Serializable snapshot) {
     checkArgument(snapshot instanceof IOStatisticsSnapshot,
         "Not an IOStatisticsSnapshot %s", snapshot);
+    return (IOStatisticsSnapshot) snapshot;
   }
 }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/functional/BiFunctionRaisingIOE.java

@@ -19,6 +19,7 @@
 package org.apache.hadoop.util.functional;
 
 import java.io.IOException;
+import java.io.UncheckedIOException;
 
 /**
  * Function of arity 2 which may raise an IOException.
@@ -37,4 +38,19 @@ public interface BiFunctionRaisingIOE<T, U, R> {
    * @throws IOException Any IO failure
    */
   R apply(T t, U u) throws IOException;
+
+  /**
+   * Apply unchecked.
+   * @param t argument
+   * @param u argument 2
+   * @return the evaluated function
+   * @throws UncheckedIOException IOE raised.
+   */
+  default R unchecked(T t, U u) {
+    try {
+      return apply(t, u);
+    } catch (IOException e) {
+      throw new UncheckedIOException(e);
+    }
+  }
 }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/functional/CallableRaisingIOE.java

@@ -19,6 +19,7 @@
 package org.apache.hadoop.util.functional;
 
 import java.io.IOException;
+import java.io.UncheckedIOException;
 
 /**
  * This is a callable which only raises an IOException.
@@ -33,4 +34,18 @@ public interface CallableRaisingIOE<R> {
    * @throws IOException Any IO failure
    */
   R apply() throws IOException;
+
+  /**
+   * Apply unchecked.
+   * @return the evaluated call
+   * @throws UncheckedIOException IOE raised.
+   */
+  default R unchecked() {
+    try {
+      return apply();
+    } catch (IOException e) {
+      throw new UncheckedIOException(e);
+    }
+  }
+
 }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/functional/FunctionRaisingIOE.java

@@ -19,6 +19,7 @@
 package org.apache.hadoop.util.functional;
 
 import java.io.IOException;
+import java.io.UncheckedIOException;
 
 /**
  * Function of arity 1 which may raise an IOException.
@@ -35,4 +36,18 @@ public interface FunctionRaisingIOE<T, R> {
    * @throws IOException Any IO failure
    */
   R apply(T t) throws IOException;
+
+  /**
+   * Apply unchecked.
+   * @param t argument
+   * @return the evaluated function
+   * @throws UncheckedIOException IOE raised.
+   */
+  default R unchecked(T t) {
+    try {
+      return apply(t);
+    } catch (IOException e) {
+      throw new UncheckedIOException(e);
+    }
+  }
 }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/functional/FunctionalIO.java

@@ -20,6 +20,7 @@
 
 import java.io.IOException;
 import java.io.UncheckedIOException;
+import java.util.function.Function;
 import java.util.function.Supplier;
 
 import org.apache.hadoop.classification.InterfaceAudience;
@@ -42,11 +43,7 @@ private FunctionalIO() {
    * @throws UncheckedIOException if an IOE was raised.
    */
   public static <T> T uncheckIOExceptions(CallableRaisingIOE<T> call) {
-    try {
-      return call.apply();
-    } catch (IOException e) {
-      throw new UncheckedIOException(e);
-    }
+    return call.unchecked();
   }
 
   /**
@@ -56,7 +53,7 @@ public static <T> T uncheckIOExceptions(CallableRaisingIOE<T> call) {
    * @return a supplier which invokes the call.
    */
   public static <T> Supplier<T> toUncheckedIOExceptionSupplier(CallableRaisingIOE<T> call) {
-    return () -> uncheckIOExceptions(call);
+    return call::unchecked;
   }
 
   /**
@@ -75,4 +72,17 @@ public static <T> T extractIOExceptions(Supplier<T> call) throws IOException {
     }
   }
 
+
+  /**
+   * Convert a {@link FunctionRaisingIOE} as a {@link Supplier}.
+   * @param fun function to wrap
+   * @param <T> type of result
+   * @return a new function which invokes the inner function and wraps
+   * exceptions.
+   */
+  public static <T, R> Function<T, R> toUncheckedFunction(FunctionRaisingIOE<T, R> fun) {
+    return fun::unchecked;
+  }
+
+
 }

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/io/wrappedio/impl/TestWrappedIO.java

@@ -58,7 +58,7 @@
 import static org.apache.hadoop.util.functional.Tuples.pair;
 
 /**
- * Test wrapped operations.
+ * Test WrappedIO operations.
  * <p>
  * This is a contract test; the base class is bonded to the local fs;
  * it is possible for other stores to implement themselves.
@@ -291,7 +291,6 @@ public void testFilesystemIOStatistics() throws Throwable {
       final Serializable roundTripped = statistics.iostatisticsSnapshot_fromJsonString(
           status);
 
-
       final Path path = methodPath();
       statistics.iostatisticsSnapshot_save(roundTripped, fs, path, true);
       final Serializable loaded = statistics.iostatisticsSnapshot_load(fs, path);

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/io/wrappedio/impl/TestWrappedStatistics.java

@@ -66,21 +66,11 @@ public class TestWrappedStatistics extends AbstractHadoopTestBase {
    */
   private final DynamicWrappedStatistics statistics = new DynamicWrappedStatistics();
 
-  /**
-   * temp dir for saving snapshots.
-   */
-  private File tempDir;
-
   /**
    * Local FS.
    */
   private LocalFileSystem local;
 
-  /**
-   * Temporary file.
-   */
-  private File jsonFile;
-
   /**
    * Path to temporary file.
    */
@@ -89,9 +79,10 @@ public class TestWrappedStatistics extends AbstractHadoopTestBase {
   @Before
   public void setUp() throws Exception {
     String testDataDir = new FileSystemTestHelper().getTestRootDir();
-    tempDir = new File(testDataDir);
+    File tempDir = new File(testDataDir);
     local = FileSystem.getLocal(new Configuration());
-    jsonFile = new File(tempDir, "snapshot.json");
+    // Temporary file.
+    File jsonFile = new File(tempDir, "snapshot.json");
     jsonPath = new Path(jsonFile.toURI());
   }
 
@@ -457,8 +448,14 @@ public void testMissingIOStatisticsMethods() throws Throwable {
 
   }
 
+
   /**
-   * Bind to an empty class to simulate a runtime where none of the methods were found
+   * Empty class to bind against and ensure all methods fail to bind.
+   */
+  private static final class StubClass { }
+
+  /**
+   * Bind to {@link StubClass} to simulate a runtime where none of the methods were found
    * through reflection, and verify the expected failure semantics.
    */
   @Test
@@ -482,10 +479,17 @@ public void testMissingContextMethods() throws Throwable {
         missing.iostatisticsContext_setThreadIOStatisticsContext(null));
   }
 
+
   /**
-   * Empty class to bind against and ensure all methods fail to bind.
+   * Validate class checks in {@code iostatisticsSnapshot_aggregate()}.
    */
-  private static final class StubClass { }
+  @Test
+  public void testStatisticCasting() throws Throwable {
+    Serializable iostats = statistics.iostatisticsSnapshot_create(null);
+    final String wrongType = "wrong type";
+    intercept(IllegalArgumentException.class, () ->
+        statistics.iostatisticsSnapshot_aggregate(iostats, wrongType));
+  }
 
 }