[FLINK-11838][flink-gs-fs-hadoop] Add utility functions

Add some utility functions used by the recoverable writer. Includes unit tests.

flink-filesystems/flink-gs-fs-hadoop/src/main/java/org/apache/flink/fs/gs/utils/BlobUtils.java

@@ -0,0 +1,63 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.flink.fs.gs.utils;
+
+import com.google.cloud.storage.BlobId;
+
+import java.net.URI;
+
+/** Utility functions related to blobs. */
+public class BlobUtils {
+
+    /** The maximum number of blobs that can be composed in a single operation. */
+    public static final int COMPOSE_MAX_BLOBS = 32;
+
+    /**
+     * Normalizes a blob id, ensuring that the generation is null.
+     *
+     * @param blobId The blob id
+     * @return The blob id with the generation set to null
+     */
+    public static BlobId normalizeBlobId(BlobId blobId) {
+        return BlobId.of(blobId.getBucket(), blobId.getName());
+    }
+
+    /**
+     * Parses a blob id from a Google storage uri, i.e. gs://bucket/foo/bar yields a blob with
+     * bucket name "bucket" and object name "foo/bar".
+     *
+     * @param uri The gs uri
+     * @return The blob id
+     */
+    public static BlobId parseUri(URI uri) {
+        String finalBucketName = uri.getAuthority();
+        if (finalBucketName == null) {
+            throw new IllegalArgumentException(String.format("Bucket name in %s is invalid", uri));
+        }
+        String path = uri.getPath();
+        if (path == null) {
+            throw new IllegalArgumentException(String.format("Object name in %s is invalid", uri));
+        }
+        String finalObjectName = path.substring(1); // remove leading slash from path
+        if (finalObjectName.isEmpty()) {
+            throw new IllegalArgumentException(String.format("Object name in %s is invalid", uri));
+        }
+        return BlobId.of(finalBucketName, finalObjectName);
+    }
+}

flink-filesystems/flink-gs-fs-hadoop/src/main/java/org/apache/flink/fs/gs/utils/ChecksumUtils.java

@@ -0,0 +1,50 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.flink.fs.gs.utils;
+
+import org.apache.flink.shaded.guava18.com.google.common.hash.HashFunction;
+import org.apache.flink.shaded.guava18.com.google.common.hash.Hashing;
+
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.util.Base64;
+
+/** Utility class related to checksums. */
+public class ChecksumUtils {
+
+    /** THe crc hash function used by Google storage. */
+    public static final HashFunction CRC_HASH_FUNCTION = Hashing.crc32c();
+
+    /** The encoder use to construct string checksums, as done by Google storage. */
+    private static final Base64.Encoder BASE64_ENCODER = Base64.getEncoder();
+
+    /**
+     * Converts an int crc32 checksum to the string format used by Google storage, which is the
+     * base64 string for the int in big-endian format.
+     *
+     * @param checksum The int checksum
+     * @return The string checksum
+     */
+    public static String convertChecksumToString(int checksum) {
+        ByteBuffer buffer = ByteBuffer.allocate(Integer.BYTES);
+        buffer.order(ByteOrder.BIG_ENDIAN);
+        buffer.putInt(checksum);
+        return BASE64_ENCODER.encodeToString(buffer.array());
+    }
+}

flink-filesystems/flink-gs-fs-hadoop/src/test/java/org/apache/flink/fs/gs/utils/BlobUtilsTest.java

@@ -0,0 +1,57 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.flink.fs.gs.utils;
+
+import com.google.cloud.storage.BlobId;
+import org.junit.Test;
+
+import java.net.URI;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+/** Test blob utilities. */
+public class BlobUtilsTest {
+
+    @Test
+    public void shouldNormalizeBlobId() {
+        BlobId normalizedBlobId = BlobUtils.normalizeBlobId(BlobId.of("bucket", "foo/bar", 12L));
+        assertEquals("bucket", normalizedBlobId.getBucket());
+        assertEquals("foo/bar", normalizedBlobId.getName());
+        assertNull(normalizedBlobId.getGeneration());
+    }
+
+    @Test
+    public void shouldParseValidUri() {
+        BlobId blobId = BlobUtils.parseUri(URI.create("gs://bucket/foo/bar"));
+        assertEquals("bucket", blobId.getBucket());
+        assertEquals("foo/bar", blobId.getName());
+        assertNull(blobId.getGeneration());
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void shouldFailToParseUriMissingBucketName() {
+        BlobUtils.parseUri(URI.create("gs:///foo/bar"));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void shouldFailToParseUriMissingObjectName() {
+        BlobUtils.parseUri(URI.create("gs://bucket/"));
+    }
+}

flink-filesystems/flink-gs-fs-hadoop/src/test/java/org/apache/flink/fs/gs/utils/ChecksumUtilsTest.java

@@ -0,0 +1,33 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.flink.fs.gs.utils;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/** Test checksum utilities. */
+public class ChecksumUtilsTest {
+
+    @Test
+    public void shouldConvertToStringChecksum() {
+        assertEquals("AAAwOQ==", ChecksumUtils.convertChecksumToString(12345));
+        assertEquals("AADUMQ==", ChecksumUtils.convertChecksumToString(54321));
+    }
+}