HDFS-4155. libhdfs implementation of hsync API. Contributed by Liang Xie.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1406373 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -17,6 +17,8 @@ Release 2.0.3-alpha - Unreleased
 
     HDFS-4059. Add number of stale DataNodes to metrics. (Jing Zhao via suresh)
 
+    HDFS-4155. libhdfs implementation of hsync API (Liang Xie via todd)
+
   IMPROVEMENTS
   
     HDFS-3925. Prettify PipelineAck#toString() for printing to a log

hadoop-hdfs-project/hadoop-hdfs/src/main/native/libhdfs/hdfs.c

@@ -1388,6 +1388,32 @@ int hdfsHFlush(hdfsFS fs, hdfsFile f)
     return 0;
 }
 
+int hdfsHSync(hdfsFS fs, hdfsFile f)
+{
+    //Get the JNIEnv* corresponding to current thread
+    JNIEnv* env = getJNIEnv();
+    if (env == NULL) {
+      errno = EINTERNAL;
+      return -1;
+    }
+
+    //Sanity check
+    if (!f || f->type != OUTPUT) {
+        errno = EBADF;
+        return -1;
+    }
+
+    jobject jOutputStream = f->file;
+    jthrowable jthr = invokeMethod(env, NULL, INSTANCE, jOutputStream,
+                     HADOOP_OSTRM, "hsync", "()V");
+    if (jthr) {
+        errno = printExceptionAndFree(env, jthr, PRINT_EXC_ALL,
+            "hdfsHSync: FSDataOutputStream#hsync");
+        return -1;
+    }
+    return 0;
+}
+
 int hdfsAvailable(hdfsFS fs, hdfsFile f)
 {
     // JAVA EQUIVALENT

hadoop-hdfs-project/hadoop-hdfs/src/main/native/libhdfs/hdfs.h

@@ -393,6 +393,17 @@ extern  "C" {
     int hdfsHFlush(hdfsFS fs, hdfsFile file);
 
 
+    /**
+     * hdfsHSync - Similar to posix fsync, Flush out the data in client's 
+     * user buffer. all the way to the disk device (but the disk may have 
+     * it in its cache).
+     * @param fs configured filesystem handle
+     * @param file file handle
+     * @return 0 on success, -1 on error and sets errno
+     */
+    int hdfsHSync(hdfsFS fs, hdfsFile file);
+
+
     /**
      * hdfsAvailable - Number of bytes that can be read from this
      * input stream without blocking.

hadoop-hdfs-project/hadoop-hdfs/src/main/native/libhdfs/test_libhdfs_threaded.c

@@ -150,6 +150,7 @@ static int doTestHdfsOperations(struct tlhThreadInfo *ti, hdfsFS fs)
         return EIO;
     }
     EXPECT_ZERO(hdfsFlush(fs, file));
+    EXPECT_ZERO(hdfsHSync(fs, file));
     EXPECT_ZERO(hdfsCloseFile(fs, file));
 
     /* Let's re-open the file for reading */