HADOOP-13321. Deprecate FileSystem APIs that promote inefficient call patterns. Contributed by Chris Nauroth and Mingliang Liu

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ChecksumFileSystem.java

@@ -605,6 +605,7 @@ boolean apply(Path p) throws IOException {
    * Rename files/dirs
    */
   @Override
+  @SuppressWarnings("deprecation")
   public boolean rename(Path src, Path dst) throws IOException {
     if (fs.isDirectory(src)) {
       return fs.rename(src, dst);
@@ -721,6 +722,7 @@ public void copyToLocalFile(boolean delSrc, Path src, Path dst)
    * If src and dst are directories, the copyCrc parameter
    * determines whether to copy CRC files.
    */
+  @SuppressWarnings("deprecation")
   public void copyToLocalFile(Path src, Path dst, boolean copyCrc)
     throws IOException {
     if (!fs.isDirectory(src)) { // source is a file

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileSystem.java

@@ -1624,6 +1624,11 @@ protected void processDeleteOnExit() {
   }
 
   /** Check if a path exists.
+   *
+   * It is highly discouraged to call this method back to back with other
+   * {@link #getFileStatus(Path)} calls, as this will involve multiple redundant
+   * RPC calls in HDFS.
+   *
    * @param f source path
    * @return true if the path exists
    * @throws IOException IO failure
@@ -1639,9 +1644,12 @@ public boolean exists(Path f) throws IOException {
   /** True iff the named path is a directory.
    * Note: Avoid using this method. Instead reuse the FileStatus
    * returned by getFileStatus() or listStatus() methods.
+   *
    * @param f path to check
    * @throws IOException IO failure
+   * @deprecated Use {@link #getFileStatus(Path)} instead
    */
+  @Deprecated
   public boolean isDirectory(Path f) throws IOException {
     try {
       return getFileStatus(f).isDirectory();
@@ -1653,9 +1661,12 @@ public boolean isDirectory(Path f) throws IOException {
   /** True iff the named path is a regular file.
    * Note: Avoid using this method. Instead reuse the FileStatus
    * returned by {@link #getFileStatus(Path)} or listStatus() methods.
+   *
    * @param f path to check
    * @throws IOException IO failure
+   * @deprecated Use {@link #getFileStatus(Path)} instead
    */
+  @Deprecated
   public boolean isFile(Path f) throws IOException {
     try {
       return getFileStatus(f).isFile();

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ftp/FTPFileSystem.java

@@ -644,6 +644,7 @@ private boolean isParentOf(Path parent, Path child) {
    * @return
    * @throws IOException
    */
+  @SuppressWarnings("deprecation")
   private boolean rename(FTPClient client, Path src, Path dst)
       throws IOException {
     Path workDir = new Path(client.printWorkingDirectory());

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AFileSystem.java

@@ -2142,6 +2142,7 @@ public boolean exists(Path f) throws IOException {
    * {@inheritDoc}
    */
   @Override
+  @SuppressWarnings("deprecation")
   public boolean isDirectory(Path f) throws IOException {
     incrementStatistic(INVOCATION_IS_DIRECTORY);
     return super.isDirectory(f);
@@ -2152,6 +2153,7 @@ public boolean isDirectory(Path f) throws IOException {
    * {@inheritDoc}
    */
   @Override
+  @SuppressWarnings("deprecation")
   public boolean isFile(Path f) throws IOException {
     incrementStatistic(INVOCATION_IS_FILE);
     return super.isFile(f);

hadoop-tools/hadoop-openstack/src/main/java/org/apache/hadoop/fs/swift/snative/SwiftNativeFileSystem.java

@@ -201,6 +201,7 @@ public long getBlockSize(Path path) throws IOException {
   }
 
   @Override
+  @SuppressWarnings("deprecation")
   public boolean isFile(Path f) throws IOException {
     try {
       FileStatus fileStatus = getFileStatus(f);
@@ -210,6 +211,7 @@ public boolean isFile(Path f) throws IOException {
     }
   }
 
+  @SuppressWarnings("deprecation")
   @Override
   public boolean isDirectory(Path f) throws IOException {