/**
* 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.hadoop.io.nativeio;
import java.io.FileDescriptor;
import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.util.NativeCodeLoader;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* JNI wrappers for various native IO-related calls not available in Java.
* These functions should generally be used alongside a fallback to another
* more portable mechanism.
*/
public class NativeIO {
// Flags for open() call from bits/fcntl.h
public static final int O_RDONLY = 00;
public static final int O_WRONLY = 01;
public static final int O_RDWR = 02;
public static final int O_CREAT = 0100;
public static final int O_EXCL = 0200;
public static final int O_NOCTTY = 0400;
public static final int O_TRUNC = 01000;
public static final int O_APPEND = 02000;
public static final int O_NONBLOCK = 04000;
public static final int O_SYNC = 010000;
public static final int O_ASYNC = 020000;
public static final int O_FSYNC = O_SYNC;
public static final int O_NDELAY = O_NONBLOCK;
// Flags for posix_fadvise() from bits/fcntl.h
/* No further special treatment. */
public static final int POSIX_FADV_NORMAL = 0;
/* Expect random page references. */
public static final int POSIX_FADV_RANDOM = 1;
/* Expect sequential page references. */
public static final int POSIX_FADV_SEQUENTIAL = 2;
/* Will need these pages. */
public static final int POSIX_FADV_WILLNEED = 3;
/* Don't need these pages. */
public static final int POSIX_FADV_DONTNEED = 4;
/* Data will be accessed once. */
public static final int POSIX_FADV_NOREUSE = 5;
/* Wait upon writeout of all pages
in the range before performing the
write. */
public static final int SYNC_FILE_RANGE_WAIT_BEFORE = 1;
/* Initiate writeout of all those
dirty pages in the range which are
not presently under writeback. */
public static final int SYNC_FILE_RANGE_WRITE = 2;
/* Wait upon writeout of all pages in
the range after performing the
write. */
public static final int SYNC_FILE_RANGE_WAIT_AFTER = 4;
private static final Log LOG = LogFactory.getLog(NativeIO.class);
private static boolean nativeLoaded = false;
private static boolean workaroundNonThreadSafePasswdCalls = false;
static final String WORKAROUND_NON_THREADSAFE_CALLS_KEY =
"hadoop.workaround.non.threadsafe.getpwuid";
static final boolean WORKAROUND_NON_THREADSAFE_CALLS_DEFAULT = false;
static {
if (NativeCodeLoader.isNativeCodeLoaded()) {
try {
Configuration conf = new Configuration();
workaroundNonThreadSafePasswdCalls = conf.getBoolean(
WORKAROUND_NON_THREADSAFE_CALLS_KEY,
WORKAROUND_NON_THREADSAFE_CALLS_DEFAULT);
initNative();
nativeLoaded = true;
} catch (Throwable t) {
// This can happen if the user has an older version of libhadoop.so
// installed - in this case we can continue without native IO
// after warning
LOG.error("Unable to initialize NativeIO libraries", t);
}
}
}
/**
* Return true if the JNI-based native IO extensions are available.
*/
public static boolean isAvailable() {
return NativeCodeLoader.isNativeCodeLoaded() && nativeLoaded;
}
/** Wrapper around open(2) */
public static native FileDescriptor open(String path, int flags, int mode) throws IOException;
/** Wrapper around chmod(2) */
public static native void chmod(String path, int mode) throws IOException;
static native void posix_fadvise(
FileDescriptor fd, long offset, long len, int flags) throws NativeIOException;
static native void sync_file_range(
FileDescriptor fd, long offset, long nbytes, int flags) throws NativeIOException;
private static native long getUIDForFDOwner(FileDescriptor fd) throws IOException;
private static native String getUserName(long uid) throws IOException;
/** Initialize the JNI method ID and class ID cache */
private static native void initNative();
private static class CachedUid {
final long timestamp;
final String username;
public CachedUid(String username, long timestamp) {
this.timestamp = timestamp;
this.username = username;
}
}
private static final Map<Long, CachedUid> uidCache =
new ConcurrentHashMap<Long, CachedUid>();
private static long cacheTimeout;
private static boolean initialized = false;
private static boolean fadvisePossible = true;
private static boolean syncFileRangePossible = true;
public static String getOwner(FileDescriptor fd) throws IOException {
ensureInitialized();
long uid = getUIDForFDOwner(fd);
CachedUid cUid = uidCache.get(uid);
long now = System.currentTimeMillis();
if (cUid != null && (cUid.timestamp + cacheTimeout) > now) {
return cUid.username;
}
String user = getUserName(uid);
LOG.debug("Got UserName " + user + " for UID " + uid +
" from the native implementation");
cUid = new CachedUid(user, now);
uidCache.put(uid, cUid);
return user;
}
/**
* Call posix_fadvise on the given file descriptor. See the manpage
* for this syscall for more information. On systems where this
* call is not available, does nothing.
*
* @throws NativeIOException if there is an error with the syscall
*/
public static void posixFadviseIfPossible(
FileDescriptor fd, long offset, long len, int flags)
throws NativeIOException {
if (nativeLoaded && fadvisePossible) {
try {
posix_fadvise(fd, offset, len, flags);
} catch (UnsupportedOperationException uoe) {
fadvisePossible = false;
} catch (UnsatisfiedLinkError ule) {
fadvisePossible = false;
}
}
}
/**
* Call sync_file_range on the given file descriptor. See the manpage
* for this syscall for more information. On systems where this
* call is not available, does nothing.
*
* @throws NativeIOException if there is an error with the syscall
*/
public static void syncFileRangeIfPossible(
FileDescriptor fd, long offset, long nbytes, int flags)
throws NativeIOException {
if (nativeLoaded && syncFileRangePossible) {
try {
sync_file_range(fd, offset, nbytes, flags);
} catch (UnsupportedOperationException uoe) {
syncFileRangePossible = false;
} catch (UnsatisfiedLinkError ule) {
syncFileRangePossible = false;
}
}
}
private synchronized static void ensureInitialized() {
if (!initialized) {
cacheTimeout =
new Configuration().getLong("hadoop.security.uid.cache.secs",
4*60*60) * 1000;
LOG.debug("Initialized cache for UID to User mapping with a cache" +
" timeout of " + cacheTimeout/1000 + " seconds.");
initialized = true;
}
}
}