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/**
* 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.hbase.util;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import edu.umd.cs.findbugs.annotations.Nullable;
import org.apache.commons.lang3.NotImplementedException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.PathFilter;
import org.apache.yetus.audience.InterfaceAudience;
import org.apache.hadoop.hbase.client.ColumnFamilyDescriptorBuilder;
import org.apache.hadoop.hbase.client.TableDescriptor;
import org.apache.hadoop.hbase.client.TableDescriptorBuilder;
import org.apache.hadoop.hbase.Coprocessor;
import org.apache.hadoop.hbase.exceptions.DeserializationException;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.regionserver.BloomType;
import org.apache.hadoop.hbase.shaded.com.google.common.annotations.VisibleForTesting;
import org.apache.hadoop.hbase.shaded.com.google.common.primitives.Ints;
import org.apache.hadoop.hbase.TableDescriptors;
import org.apache.hadoop.hbase.TableInfoMissingException;
import org.apache.hadoop.hbase.TableName;
/**
* Implementation of {@link TableDescriptors} that reads descriptors from the
* passed filesystem. It expects descriptors to be in a file in the
* {@link #TABLEINFO_DIR} subdir of the table's directory in FS. Can be read-only
* -- i.e. does not modify the filesystem or can be read and write.
*
* Also has utility for keeping up the table descriptors tableinfo file.
* The table schema file is kept in the {@link #TABLEINFO_DIR} subdir
* of the table directory in the filesystem.
* It has a {@link #TABLEINFO_FILE_PREFIX} and then a suffix that is the
* edit sequenceid: e.g. .tableinfo.0000000003. This sequenceid
* is always increasing. It starts at zero. The table schema file with the
* highest sequenceid has the most recent schema edit. Usually there is one file
* only, the most recent but there may be short periods where there are more
* than one file. Old files are eventually cleaned. Presumption is that there
* will not be lots of concurrent clients making table schema edits. If so,
* the below needs a bit of a reworking and perhaps some supporting api in hdfs.
*/
@InterfaceAudience.Private
public class FSTableDescriptors implements TableDescriptors {
private static final Log LOG = LogFactory.getLog(FSTableDescriptors.class);
private final FileSystem fs;
private final Path rootdir;
private final boolean fsreadonly;
private volatile boolean usecache;
private volatile boolean fsvisited;
@VisibleForTesting
long cachehits = 0;
@VisibleForTesting
long invocations = 0;
/**
* The file name prefix used to store HTD in HDFS
*/
static final String TABLEINFO_FILE_PREFIX = ".tableinfo";
static final String TABLEINFO_DIR = ".tabledesc";
static final String TMP_DIR = ".tmp";
// This cache does not age out the old stuff. Thinking is that the amount
// of data we keep up in here is so small, no need to do occasional purge.
// TODO.
private final Map cache = new ConcurrentHashMap<>();
/**
* Table descriptor for hbase:meta catalog table
*/
private final TableDescriptor metaTableDescriptor;
/**
* Construct a FSTableDescriptors instance using the hbase root dir of the given
* conf and the filesystem where that root dir lives.
* This instance can do write operations (is not read only).
*/
public FSTableDescriptors(final Configuration conf) throws IOException {
this(conf, FSUtils.getCurrentFileSystem(conf), FSUtils.getRootDir(conf));
}
public FSTableDescriptors(final Configuration conf, final FileSystem fs, final Path rootdir)
throws IOException {
this(conf, fs, rootdir, false, true);
}
/**
* @param fsreadonly True if we are read-only when it comes to filesystem
* operations; i.e. on remove, we do not do delete in fs.
*/
public FSTableDescriptors(final Configuration conf, final FileSystem fs,
final Path rootdir, final boolean fsreadonly, final boolean usecache) throws IOException {
this(conf, fs, rootdir, fsreadonly, usecache, null);
}
/**
* @param fsreadonly True if we are read-only when it comes to filesystem
* operations; i.e. on remove, we do not do delete in fs.
* @param metaObserver Used by HMaster. It need to modify the META_REPLICAS_NUM for meta table descriptor.
* see HMaster#finishActiveMasterInitialization
* TODO: This is a workaround. Should remove this ugly code...
*/
public FSTableDescriptors(final Configuration conf, final FileSystem fs,
final Path rootdir, final boolean fsreadonly, final boolean usecache,
Function metaObserver) throws IOException {
this.fs = fs;
this.rootdir = rootdir;
this.fsreadonly = fsreadonly;
this.usecache = usecache;
this.metaTableDescriptor = metaObserver == null ? createMetaTableDescriptor(conf)
: metaObserver.apply(createMetaTableDescriptorBuilder(conf)).build();
}
@VisibleForTesting
public static TableDescriptorBuilder createMetaTableDescriptorBuilder(final Configuration conf) throws IOException {
return TableDescriptorBuilder.newBuilder(TableName.META_TABLE_NAME)
.addColumnFamily(ColumnFamilyDescriptorBuilder.newBuilder(HConstants.CATALOG_FAMILY)
.setMaxVersions(conf.getInt(HConstants.HBASE_META_VERSIONS,
HConstants.DEFAULT_HBASE_META_VERSIONS))
.setInMemory(true)
.setBlocksize(conf.getInt(HConstants.HBASE_META_BLOCK_SIZE,
HConstants.DEFAULT_HBASE_META_BLOCK_SIZE))
.setScope(HConstants.REPLICATION_SCOPE_LOCAL)
// Disable blooms for meta. Needs work. Seems to mess w/ getClosestOrBefore.
.setBloomFilterType(BloomType.NONE)
// Enable cache of data blocks in L1 if more than one caching tier deployed:
// e.g. if using CombinedBlockCache (BucketCache).
.setCacheDataInL1(true)
.build())
.addColumnFamily(ColumnFamilyDescriptorBuilder.newBuilder(HConstants.REPLICATION_BARRIER_FAMILY)
.setMaxVersions(conf.getInt(HConstants.HBASE_META_VERSIONS,
HConstants.DEFAULT_HBASE_META_VERSIONS))
.setInMemory(true)
.setBlocksize(conf.getInt(HConstants.HBASE_META_BLOCK_SIZE,
HConstants.DEFAULT_HBASE_META_BLOCK_SIZE))
.setScope(HConstants.REPLICATION_SCOPE_LOCAL)
// Disable blooms for meta. Needs work. Seems to mess w/ getClosestOrBefore.
.setBloomFilterType(BloomType.NONE)
// Enable cache of data blocks in L1 if more than one caching tier deployed:
// e.g. if using CombinedBlockCache (BucketCache).
.setCacheDataInL1(true)
.build())
.addColumnFamily(ColumnFamilyDescriptorBuilder.newBuilder(HConstants.REPLICATION_POSITION_FAMILY)
.setMaxVersions(conf.getInt(HConstants.HBASE_META_VERSIONS,
HConstants.DEFAULT_HBASE_META_VERSIONS))
.setInMemory(true)
.setBlocksize(conf.getInt(HConstants.HBASE_META_BLOCK_SIZE,
HConstants.DEFAULT_HBASE_META_BLOCK_SIZE))
.setScope(HConstants.REPLICATION_SCOPE_LOCAL)
// Disable blooms for meta. Needs work. Seems to mess w/ getClosestOrBefore.
.setBloomFilterType(BloomType.NONE)
// Enable cache of data blocks in L1 if more than one caching tier deployed:
// e.g. if using CombinedBlockCache (BucketCache).
.setCacheDataInL1(true)
.build())
.addColumnFamily(ColumnFamilyDescriptorBuilder.newBuilder(HConstants.REPLICATION_META_FAMILY)
.setMaxVersions(conf.getInt(HConstants.HBASE_META_VERSIONS,
HConstants.DEFAULT_HBASE_META_VERSIONS))
.setInMemory(true)
.setBlocksize(conf.getInt(HConstants.HBASE_META_BLOCK_SIZE,
HConstants.DEFAULT_HBASE_META_BLOCK_SIZE))
.setScope(HConstants.REPLICATION_SCOPE_LOCAL)
// Disable blooms for meta. Needs work. Seems to mess w/ getClosestOrBefore.
.setBloomFilterType(BloomType.NONE)
// Enable cache of data blocks in L1 if more than one caching tier deployed:
// e.g. if using CombinedBlockCache (BucketCache).
.setCacheDataInL1(true)
.build())
.addColumnFamily(ColumnFamilyDescriptorBuilder.newBuilder(HConstants.TABLE_FAMILY)
// Ten is arbitrary number. Keep versions to help debugging.
.setMaxVersions(10)
.setInMemory(true)
.setBlocksize(8 * 1024)
.setScope(HConstants.REPLICATION_SCOPE_LOCAL)
// Disable blooms for meta. Needs work. Seems to mess w/ getClosestOrBefore.
.setBloomFilterType(BloomType.NONE)
// Enable cache of data blocks in L1 if more than one caching tier deployed:
// e.g. if using CombinedBlockCache (BucketCache).
.setCacheDataInL1(true)
.build())
.addCoprocessor("org.apache.hadoop.hbase.coprocessor.MultiRowMutationEndpoint",
null, Coprocessor.PRIORITY_SYSTEM, null);
}
@VisibleForTesting
public static TableDescriptor createMetaTableDescriptor(final Configuration conf)
throws IOException {
return createMetaTableDescriptorBuilder(conf).build();
}
@Override
public void setCacheOn() throws IOException {
this.cache.clear();
this.usecache = true;
}
@Override
public void setCacheOff() throws IOException {
this.usecache = false;
this.cache.clear();
}
@VisibleForTesting
public boolean isUsecache() {
return this.usecache;
}
/**
* Get the current table descriptor for the given table, or null if none exists.
*
* Uses a local cache of the descriptor but still checks the filesystem on each call
* to see if a newer file has been created since the cached one was read.
*/
@Override
@Nullable
public TableDescriptor get(final TableName tablename)
throws IOException {
invocations++;
if (TableName.META_TABLE_NAME.equals(tablename)) {
cachehits++;
return metaTableDescriptor;
}
// hbase:meta is already handled. If some one tries to get the descriptor for
// .logs, .oldlogs or .corrupt throw an exception.
if (HConstants.HBASE_NON_USER_TABLE_DIRS.contains(tablename.getNameAsString())) {
throw new IOException("No descriptor found for non table = " + tablename);
}
if (usecache) {
// Look in cache of descriptors.
TableDescriptor cachedtdm = this.cache.get(tablename);
if (cachedtdm != null) {
cachehits++;
return cachedtdm;
}
}
TableDescriptor tdmt = null;
try {
tdmt = getTableDescriptorFromFs(fs, rootdir, tablename);
} catch (NullPointerException e) {
LOG.debug("Exception during readTableDecriptor. Current table name = "
+ tablename, e);
} catch (TableInfoMissingException e) {
// ignore. This is regular operation
} catch (IOException ioe) {
LOG.debug("Exception during readTableDecriptor. Current table name = "
+ tablename, ioe);
}
// last HTD written wins
if (usecache && tdmt != null) {
this.cache.put(tablename, tdmt);
}
return tdmt;
}
/**
* Returns a map from table name to table descriptor for all tables.
*/
@Override
public Map getAllDescriptors()
throws IOException {
Map tds = new TreeMap<>();
if (fsvisited && usecache) {
for (Map.Entry entry: this.cache.entrySet()) {
tds.put(entry.getKey().toString(), entry.getValue());
}
// add hbase:meta to the response
tds.put(this.metaTableDescriptor.getTableName().getNameAsString(), metaTableDescriptor);
} else {
LOG.debug("Fetching table descriptors from the filesystem.");
boolean allvisited = true;
for (Path d : FSUtils.getTableDirs(fs, rootdir)) {
TableDescriptor htd = null;
try {
htd = get(FSUtils.getTableName(d));
} catch (FileNotFoundException fnfe) {
// inability of retrieving one HTD shouldn't stop getting the remaining
LOG.warn("Trouble retrieving htd", fnfe);
}
if (htd == null) {
allvisited = false;
continue;
} else {
tds.put(htd.getTableName().getNameAsString(), htd);
}
fsvisited = allvisited;
}
}
return tds;
}
/**
* Returns a map from table name to table descriptor for all tables.
*/
@Override
public Map getAll() throws IOException {
Map htds = new TreeMap<>();
Map allDescriptors = getAllDescriptors();
for (Map.Entry entry : allDescriptors
.entrySet()) {
htds.put(entry.getKey(), entry.getValue());
}
return htds;
}
/**
* Find descriptors by namespace.
* @see #get(org.apache.hadoop.hbase.TableName)
*/
@Override
public Map getByNamespace(String name)
throws IOException {
Map htds = new TreeMap<>();
List tableDirs =
FSUtils.getLocalTableDirs(fs, FSUtils.getNamespaceDir(rootdir, name));
for (Path d: tableDirs) {
TableDescriptor htd = null;
try {
htd = get(FSUtils.getTableName(d));
} catch (FileNotFoundException fnfe) {
// inability of retrieving one HTD shouldn't stop getting the remaining
LOG.warn("Trouble retrieving htd", fnfe);
}
if (htd == null) continue;
htds.put(FSUtils.getTableName(d).getNameAsString(), htd);
}
return htds;
}
/**
* Adds (or updates) the table descriptor to the FileSystem
* and updates the local cache with it.
*/
@Override
public void add(TableDescriptor htd) throws IOException {
if (fsreadonly) {
throw new NotImplementedException("Cannot add a table descriptor - in read only mode");
}
TableName tableName = htd.getTableName();
if (TableName.META_TABLE_NAME.equals(tableName)) {
throw new NotImplementedException(HConstants.NOT_IMPLEMENTED);
}
if (HConstants.HBASE_NON_USER_TABLE_DIRS.contains(tableName.getNameAsString())) {
throw new NotImplementedException(
"Cannot add a table descriptor for a reserved subdirectory name: "
+ htd.getTableName().getNameAsString());
}
updateTableDescriptor(htd);
}
/**
* Removes the table descriptor from the local cache and returns it.
* If not in read only mode, it also deletes the entire table directory(!)
* from the FileSystem.
*/
@Override
public TableDescriptor remove(final TableName tablename)
throws IOException {
if (fsreadonly) {
throw new NotImplementedException("Cannot remove a table descriptor - in read only mode");
}
Path tabledir = getTableDir(tablename);
if (this.fs.exists(tabledir)) {
if (!this.fs.delete(tabledir, true)) {
throw new IOException("Failed delete of " + tabledir.toString());
}
}
TableDescriptor descriptor = this.cache.remove(tablename);
return descriptor;
}
/**
* Checks if a current table info file exists for the given table
*
* @param tableName name of table
* @return true if exists
* @throws IOException
*/
public boolean isTableInfoExists(TableName tableName) throws IOException {
return getTableInfoPath(tableName) != null;
}
/**
* Find the most current table info file for the given table in the hbase root directory.
* @return The file status of the current table info file or null if it does not exist
*/
private FileStatus getTableInfoPath(final TableName tableName) throws IOException {
Path tableDir = getTableDir(tableName);
return getTableInfoPath(tableDir);
}
private FileStatus getTableInfoPath(Path tableDir)
throws IOException {
return getTableInfoPath(fs, tableDir, !fsreadonly);
}
/**
* Find the most current table info file for the table located in the given table directory.
*
* Looks within the {@link #TABLEINFO_DIR} subdirectory of the given directory for any table info
* files and takes the 'current' one - meaning the one with the highest sequence number if present
* or no sequence number at all if none exist (for backward compatibility from before there
* were sequence numbers).
*
* @return The file status of the current table info file or null if it does not exist
* @throws IOException
*/
public static FileStatus getTableInfoPath(FileSystem fs, Path tableDir)
throws IOException {
return getTableInfoPath(fs, tableDir, false);
}
/**
* Find the most current table info file for the table in the given table directory.
*
* Looks within the {@link #TABLEINFO_DIR} subdirectory of the given directory for any table info
* files and takes the 'current' one - meaning the one with the highest sequence number if
* present or no sequence number at all if none exist (for backward compatibility from before
* there were sequence numbers).
* If there are multiple table info files found and removeOldFiles is true it also deletes the
* older files.
*
* @return The file status of the current table info file or null if none exist
* @throws IOException
*/
private static FileStatus getTableInfoPath(FileSystem fs, Path tableDir, boolean removeOldFiles)
throws IOException {
Path tableInfoDir = new Path(tableDir, TABLEINFO_DIR);
return getCurrentTableInfoStatus(fs, tableInfoDir, removeOldFiles);
}
/**
* Find the most current table info file in the given directory
*
* Looks within the given directory for any table info files
* and takes the 'current' one - meaning the one with the highest sequence number if present
* or no sequence number at all if none exist (for backward compatibility from before there
* were sequence numbers).
* If there are multiple possible files found
* and the we're not in read only mode it also deletes the older files.
*
* @return The file status of the current table info file or null if it does not exist
* @throws IOException
*/
// only visible for FSTableDescriptorMigrationToSubdir, can be removed with that
static FileStatus getCurrentTableInfoStatus(FileSystem fs, Path dir, boolean removeOldFiles)
throws IOException {
FileStatus [] status = FSUtils.listStatus(fs, dir, TABLEINFO_PATHFILTER);
if (status == null || status.length < 1) return null;
FileStatus mostCurrent = null;
for (FileStatus file : status) {
if (mostCurrent == null || TABLEINFO_FILESTATUS_COMPARATOR.compare(file, mostCurrent) < 0) {
mostCurrent = file;
}
}
if (removeOldFiles && status.length > 1) {
// Clean away old versions
for (FileStatus file : status) {
Path path = file.getPath();
if (file != mostCurrent) {
if (!fs.delete(file.getPath(), false)) {
LOG.warn("Failed cleanup of " + path);
} else {
LOG.debug("Cleaned up old tableinfo file " + path);
}
}
}
}
return mostCurrent;
}
/**
* Compare {@link FileStatus} instances by {@link Path#getName()}. Returns in
* reverse order.
*/
@VisibleForTesting
static final Comparator TABLEINFO_FILESTATUS_COMPARATOR =
new Comparator() {
@Override
public int compare(FileStatus left, FileStatus right) {
return right.compareTo(left);
}};
/**
* Return the table directory in HDFS
*/
@VisibleForTesting Path getTableDir(final TableName tableName) {
return FSUtils.getTableDir(rootdir, tableName);
}
private static final PathFilter TABLEINFO_PATHFILTER = new PathFilter() {
@Override
public boolean accept(Path p) {
// Accept any file that starts with TABLEINFO_NAME
return p.getName().startsWith(TABLEINFO_FILE_PREFIX);
}};
/**
* Width of the sequenceid that is a suffix on a tableinfo file.
*/
@VisibleForTesting static final int WIDTH_OF_SEQUENCE_ID = 10;
/*
* @param number Number to use as suffix.
* @return Returns zero-prefixed decimal version of passed
* number (Does absolute in case number is negative).
*/
private static String formatTableInfoSequenceId(final int number) {
byte [] b = new byte[WIDTH_OF_SEQUENCE_ID];
int d = Math.abs(number);
for (int i = b.length - 1; i >= 0; i--) {
b[i] = (byte)((d % 10) + '0');
d /= 10;
}
return Bytes.toString(b);
}
/**
* Regex to eat up sequenceid suffix on a .tableinfo file.
* Use regex because may encounter oldstyle .tableinfos where there is no
* sequenceid on the end.
*/
private static final Pattern TABLEINFO_FILE_REGEX =
Pattern.compile(TABLEINFO_FILE_PREFIX + "(\\.([0-9]{" + WIDTH_OF_SEQUENCE_ID + "}))?$");
/**
* @param p Path to a .tableinfo file.
* @return The current editid or 0 if none found.
*/
@VisibleForTesting static int getTableInfoSequenceId(final Path p) {
if (p == null) return 0;
Matcher m = TABLEINFO_FILE_REGEX.matcher(p.getName());
if (!m.matches()) throw new IllegalArgumentException(p.toString());
String suffix = m.group(2);
if (suffix == null || suffix.length() <= 0) return 0;
return Integer.parseInt(m.group(2));
}
/**
* @param sequenceid
* @return Name of tableinfo file.
*/
@VisibleForTesting static String getTableInfoFileName(final int sequenceid) {
return TABLEINFO_FILE_PREFIX + "." + formatTableInfoSequenceId(sequenceid);
}
/**
* Returns the latest table descriptor for the given table directly from the file system
* if it exists, bypassing the local cache.
* Returns null if it's not found.
*/
public static TableDescriptor getTableDescriptorFromFs(FileSystem fs,
Path hbaseRootDir, TableName tableName) throws IOException {
Path tableDir = FSUtils.getTableDir(hbaseRootDir, tableName);
return getTableDescriptorFromFs(fs, tableDir);
}
/**
* Returns the latest table descriptor for the table located at the given directory
* directly from the file system if it exists.
* @throws TableInfoMissingException if there is no descriptor
*/
public static TableDescriptor getTableDescriptorFromFs(FileSystem fs, Path tableDir)
throws IOException {
FileStatus status = getTableInfoPath(fs, tableDir, false);
if (status == null) {
throw new TableInfoMissingException("No table descriptor file under " + tableDir);
}
return readTableDescriptor(fs, status);
}
private static TableDescriptor readTableDescriptor(FileSystem fs, FileStatus status)
throws IOException {
int len = Ints.checkedCast(status.getLen());
byte [] content = new byte[len];
FSDataInputStream fsDataInputStream = fs.open(status.getPath());
try {
fsDataInputStream.readFully(content);
} finally {
fsDataInputStream.close();
}
TableDescriptor htd = null;
try {
htd = TableDescriptorBuilder.parseFrom(content);
} catch (DeserializationException e) {
throw new IOException("content=" + Bytes.toShort(content), e);
}
return htd;
}
/**
* Update table descriptor on the file system
* @throws IOException Thrown if failed update.
* @throws NotImplementedException if in read only mode
*/
@VisibleForTesting Path updateTableDescriptor(TableDescriptor td)
throws IOException {
if (fsreadonly) {
throw new NotImplementedException("Cannot update a table descriptor - in read only mode");
}
TableName tableName = td.getTableName();
Path tableDir = getTableDir(tableName);
Path p = writeTableDescriptor(fs, td, tableDir, getTableInfoPath(tableDir));
if (p == null) throw new IOException("Failed update");
LOG.info("Updated tableinfo=" + p);
if (usecache) {
this.cache.put(td.getTableName(), td);
}
return p;
}
/**
* Deletes all the table descriptor files from the file system.
* Used in unit tests only.
* @throws NotImplementedException if in read only mode
*/
public void deleteTableDescriptorIfExists(TableName tableName) throws IOException {
if (fsreadonly) {
throw new NotImplementedException("Cannot delete a table descriptor - in read only mode");
}
Path tableDir = getTableDir(tableName);
Path tableInfoDir = new Path(tableDir, TABLEINFO_DIR);
deleteTableDescriptorFiles(fs, tableInfoDir, Integer.MAX_VALUE);
}
/**
* Deletes files matching the table info file pattern within the given directory
* whose sequenceId is at most the given max sequenceId.
*/
private static void deleteTableDescriptorFiles(FileSystem fs, Path dir, int maxSequenceId)
throws IOException {
FileStatus [] status = FSUtils.listStatus(fs, dir, TABLEINFO_PATHFILTER);
for (FileStatus file : status) {
Path path = file.getPath();
int sequenceId = getTableInfoSequenceId(path);
if (sequenceId <= maxSequenceId) {
boolean success = FSUtils.delete(fs, path, false);
if (success) {
LOG.debug("Deleted table descriptor at " + path);
} else {
LOG.error("Failed to delete descriptor at " + path);
}
}
}
}
/**
* Attempts to write a new table descriptor to the given table's directory.
* It first writes it to the .tmp dir then uses an atomic rename to move it into place.
* It begins at the currentSequenceId + 1 and tries 10 times to find a new sequence number
* not already in use.
* Removes the current descriptor file if passed in.
*
* @return Descriptor file or null if we failed write.
*/
private static Path writeTableDescriptor(final FileSystem fs,
final TableDescriptor htd, final Path tableDir,
final FileStatus currentDescriptorFile)
throws IOException {
// Get temporary dir into which we'll first write a file to avoid half-written file phenomenon.
// This directory is never removed to avoid removing it out from under a concurrent writer.
Path tmpTableDir = new Path(tableDir, TMP_DIR);
Path tableInfoDir = new Path(tableDir, TABLEINFO_DIR);
// What is current sequenceid? We read the current sequenceid from
// the current file. After we read it, another thread could come in and
// compete with us writing out next version of file. The below retries
// should help in this case some but its hard to do guarantees in face of
// concurrent schema edits.
int currentSequenceId = currentDescriptorFile == null ? 0 :
getTableInfoSequenceId(currentDescriptorFile.getPath());
int newSequenceId = currentSequenceId;
// Put arbitrary upperbound on how often we retry
int retries = 10;
int retrymax = currentSequenceId + retries;
Path tableInfoDirPath = null;
do {
newSequenceId += 1;
String filename = getTableInfoFileName(newSequenceId);
Path tempPath = new Path(tmpTableDir, filename);
if (fs.exists(tempPath)) {
LOG.debug(tempPath + " exists; retrying up to " + retries + " times");
continue;
}
tableInfoDirPath = new Path(tableInfoDir, filename);
try {
writeTD(fs, tempPath, htd);
fs.mkdirs(tableInfoDirPath.getParent());
if (!fs.rename(tempPath, tableInfoDirPath)) {
throw new IOException("Failed rename of " + tempPath + " to " + tableInfoDirPath);
}
LOG.debug("Wrote descriptor into: " + tableInfoDirPath);
} catch (IOException ioe) {
// Presume clash of names or something; go around again.
LOG.debug("Failed write and/or rename; retrying", ioe);
if (!FSUtils.deleteDirectory(fs, tempPath)) {
LOG.warn("Failed cleanup of " + tempPath);
}
tableInfoDirPath = null;
continue;
}
break;
} while (newSequenceId < retrymax);
if (tableInfoDirPath != null) {
// if we succeeded, remove old table info files.
deleteTableDescriptorFiles(fs, tableInfoDir, newSequenceId - 1);
}
return tableInfoDirPath;
}
private static void writeTD(final FileSystem fs, final Path p, final TableDescriptor htd)
throws IOException {
FSDataOutputStream out = fs.create(p, false);
try {
// We used to write this file out as a serialized HTD Writable followed by two '\n's and then
// the toString version of HTD. Now we just write out the pb serialization.
out.write(TableDescriptorBuilder.toByteArray(htd));
} finally {
out.close();
}
}
/**
* Create new TableDescriptor in HDFS. Happens when we are creating table.
* Used by tests.
* @return True if we successfully created file.
*/
public boolean createTableDescriptor(TableDescriptor htd) throws IOException {
return createTableDescriptor(htd, false);
}
/**
* Create new TableDescriptor in HDFS. Happens when we are creating table. If
* forceCreation is true then even if previous table descriptor is present it
* will be overwritten
*
* @return True if we successfully created file.
*/
public boolean createTableDescriptor(TableDescriptor htd, boolean forceCreation)
throws IOException {
Path tableDir = getTableDir(htd.getTableName());
return createTableDescriptorForTableDirectory(tableDir, htd, forceCreation);
}
/**
* Create a new TableDescriptor in HDFS in the specified table directory. Happens when we create
* a new table or snapshot a table.
* @param tableDir table directory under which we should write the file
* @param htd description of the table to write
* @param forceCreation if true,then even if previous table descriptor is present it will
* be overwritten
* @return true if the we successfully created the file, false if the file
* already exists and we weren't forcing the descriptor creation.
* @throws IOException if a filesystem error occurs
*/
public boolean createTableDescriptorForTableDirectory(Path tableDir,
TableDescriptor htd, boolean forceCreation) throws IOException {
if (fsreadonly) {
throw new NotImplementedException("Cannot create a table descriptor - in read only mode");
}
FileStatus status = getTableInfoPath(fs, tableDir);
if (status != null) {
LOG.debug("Current tableInfoPath = " + status.getPath());
if (!forceCreation) {
if (fs.exists(status.getPath()) && status.getLen() > 0) {
if (readTableDescriptor(fs, status).equals(htd)) {
LOG.debug("TableInfo already exists.. Skipping creation");
return false;
}
}
}
}
Path p = writeTableDescriptor(fs, htd, tableDir, status);
return p != null;
}
}