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Posted to commits@hbase.apache.org by st...@apache.org on 2011/10/20 01:13:20 UTC
svn commit: r1186559 - in /hbase/trunk: CHANGES.txt
src/main/java/org/apache/hadoop/hbase/HTableDescriptor.java
src/main/java/org/apache/hadoop/hbase/master/MasterFileSystem.java
Author: stack
Date: Wed Oct 19 23:13:20 2011
New Revision: 1186559
URL: http://svn.apache.org/viewvc?rev=1186559&view=rev
Log:
HBASE-4486 Improve Javadoc for HTableDescriptor
Modified:
hbase/trunk/CHANGES.txt
hbase/trunk/src/main/java/org/apache/hadoop/hbase/HTableDescriptor.java
hbase/trunk/src/main/java/org/apache/hadoop/hbase/master/MasterFileSystem.java
Modified: hbase/trunk/CHANGES.txt
URL: http://svn.apache.org/viewvc/hbase/trunk/CHANGES.txt?rev=1186559&r1=1186558&r2=1186559&view=diff
==============================================================================
--- hbase/trunk/CHANGES.txt (original)
+++ hbase/trunk/CHANGES.txt Wed Oct 19 23:13:20 2011
@@ -630,6 +630,7 @@ Release 0.92.0 - Unreleased
HBASE-4606 Remove spam in HCM and fix a list.size == 0
HBASE-3581 hbase rpc should send size of response
HBASE-4585 Avoid seek operation when current kv is deleted(Liyin Tang)
+ HBASE-4486 Improve Javadoc for HTableDescriptor (Akash Ashok)
TASKS
Modified: hbase/trunk/src/main/java/org/apache/hadoop/hbase/HTableDescriptor.java
URL: http://svn.apache.org/viewvc/hbase/trunk/src/main/java/org/apache/hadoop/hbase/HTableDescriptor.java?rev=1186559&r1=1186558&r2=1186559&view=diff
==============================================================================
--- hbase/trunk/src/main/java/org/apache/hadoop/hbase/HTableDescriptor.java (original)
+++ hbase/trunk/src/main/java/org/apache/hadoop/hbase/HTableDescriptor.java Wed Oct 19 23:13:20 2011
@@ -39,82 +39,137 @@ import org.apache.hadoop.hbase.util.Byte
import org.apache.hadoop.io.WritableComparable;
/**
- * HTableDescriptor contains the name of an HTable, and its
- * column families.
+ * HTableDescriptor contains the details about an HBase table such as the descriptors of
+ * all the column families, is the table a catalog table, <code> -ROOT- </code> or
+ * <code> .META. </code>, is the table is read only, the maximum size of the memstore,
+ * when the region split should occur, coprocessors associated with it etc...
*/
public class HTableDescriptor implements WritableComparable<HTableDescriptor> {
- // Changes prior to version 3 were not recorded here.
- // Version 3 adds metadata as a map where keys and values are byte[].
- // Version 4 adds indexes
- // Version 5 removed transactional pollution -- e.g. indexes
- public static final byte TABLE_DESCRIPTOR_VERSION = 5;
+ /**
+ * Changes prior to version 3 were not recorded here.
+ * Version 3 adds metadata as a map where keys and values are byte[].
+ * Version 4 adds indexes
+ * Version 5 removed transactional pollution -- e.g. indexes
+ */
+ private static final byte TABLE_DESCRIPTOR_VERSION = 5;
private byte [] name = HConstants.EMPTY_BYTE_ARRAY;
+
private String nameAsString = "";
- // Table metadata
+ /**
+ * A map which holds the metadata information of the table. This metadata
+ * includes values like IS_ROOT, IS_META, DEFERRED_LOG_FLUSH, SPLIT_POLICY,
+ * MAX_FILE_SIZE, READONLY, MEMSTORE_FLUSHSIZE etc...
+ */
protected Map<ImmutableBytesWritable, ImmutableBytesWritable> values =
new HashMap<ImmutableBytesWritable, ImmutableBytesWritable>();
- public static final String FAMILIES = "FAMILIES";
- public static final ImmutableBytesWritable FAMILIES_KEY =
- new ImmutableBytesWritable(Bytes.toBytes(FAMILIES));
+ private static final String FAMILIES = "FAMILIES";
+
+ private static final String SPLIT_POLICY = "SPLIT_POLICY";
+
+ /**
+ * <em>INTERNAL</em> Used by HBase Shell interface to access this metadata
+ * attribute which denotes the maximum size of the store file after which
+ * a region split occurs
+ *
+ * @see #getMaxFileSize()
+ */
public static final String MAX_FILESIZE = "MAX_FILESIZE";
- public static final ImmutableBytesWritable MAX_FILESIZE_KEY =
+ private static final ImmutableBytesWritable MAX_FILESIZE_KEY =
new ImmutableBytesWritable(Bytes.toBytes(MAX_FILESIZE));
-
- // The class which determines when a region should split
- public static final String SPLIT_POLICY = "SPLIT_POLICY";
- public static final ImmutableBytesWritable SPLIT_POLICY_KEY =
- new ImmutableBytesWritable(Bytes.toBytes(SPLIT_POLICY));
+ /**
+ * <em>INTERNAL</em> Used by rest interface to access this metadata
+ * attribute which denotes if the table is Read Only
+ *
+ * @see #isReadOnly()
+ */
public static final String READONLY = "READONLY";
- public static final ImmutableBytesWritable READONLY_KEY =
+ private static final ImmutableBytesWritable READONLY_KEY =
new ImmutableBytesWritable(Bytes.toBytes(READONLY));
+
+ /**
+ * <em>INTERNAL</em> Used by HBase Shell interface to access this metadata
+ * attribute which represents the maximum size of the memstore after which
+ * its contents are flushed onto the disk
+ *
+ * @see #getMemStoreFlushSize()
+ */
public static final String MEMSTORE_FLUSHSIZE = "MEMSTORE_FLUSHSIZE";
- public static final ImmutableBytesWritable MEMSTORE_FLUSHSIZE_KEY =
+ private static final ImmutableBytesWritable MEMSTORE_FLUSHSIZE_KEY =
new ImmutableBytesWritable(Bytes.toBytes(MEMSTORE_FLUSHSIZE));
+
+ /**
+ * <em>INTERNAL</em> Used by rest interface to access this metadata
+ * attribute which denotes if the table is a -ROOT- region or not
+ *
+ * @see #isRootRegion()
+ */
public static final String IS_ROOT = "IS_ROOT";
- public static final ImmutableBytesWritable IS_ROOT_KEY =
+ private static final ImmutableBytesWritable IS_ROOT_KEY =
new ImmutableBytesWritable(Bytes.toBytes(IS_ROOT));
+
+ /**
+ * <em>INTERNAL</em> Used by rest interface to access this metadata
+ * attribute which denotes if it is a catalog table, either
+ * <code> .META. </code> or <code> -ROOT- </code>
+ *
+ * @see #isMetaRegion()
+ */
public static final String IS_META = "IS_META";
-
- public static final ImmutableBytesWritable IS_META_KEY =
+ private static final ImmutableBytesWritable IS_META_KEY =
new ImmutableBytesWritable(Bytes.toBytes(IS_META));
+ /**
+ * <em>INTERNAL</em> Used by HBase Shell interface to access this metadata
+ * attribute which denotes if the deferred log flush option is enabled
+ *
+ * @see #getDeferredLogFlush()
+ */
public static final String DEFERRED_LOG_FLUSH = "DEFERRED_LOG_FLUSH";
- public static final ImmutableBytesWritable DEFERRED_LOG_FLUSH_KEY =
+ private static final ImmutableBytesWritable DEFERRED_LOG_FLUSH_KEY =
new ImmutableBytesWritable(Bytes.toBytes(DEFERRED_LOG_FLUSH));
-
- // The below are ugly but better than creating them each time till we
- // replace booleans being saved as Strings with plain booleans. Need a
- // migration script to do this. TODO.
+ /*
+ * The below are ugly but better than creating them each time till we
+ * replace booleans being saved as Strings with plain booleans. Need a
+ * migration script to do this. TODO.
+ */
private static final ImmutableBytesWritable FALSE =
new ImmutableBytesWritable(Bytes.toBytes(Boolean.FALSE.toString()));
+
private static final ImmutableBytesWritable TRUE =
new ImmutableBytesWritable(Bytes.toBytes(Boolean.TRUE.toString()));
+ private static final boolean DEFAULT_DEFERRED_LOG_FLUSH = false;
+
+ /**
+ * Constant that denotes whether the table is READONLY by default and is false
+ */
public static final boolean DEFAULT_READONLY = false;
+ /**
+ * Constant that denotes the maximum default size of the memstore after which
+ * the contents are flushed to the store files
+ */
public static final long DEFAULT_MEMSTORE_FLUSH_SIZE = 1024*1024*64L;
- public static final long DEFAULT_MAX_FILESIZE = 1024*1024*256L;
-
- public static final boolean DEFAULT_DEFERRED_LOG_FLUSH = false;
-
private volatile Boolean meta = null;
private volatile Boolean root = null;
private Boolean isDeferredLog = null;
- // Key is hash of the family name.
- public final Map<byte [], HColumnDescriptor> families =
+ /**
+ * Maps column family name to the respective HColumnDescriptors
+ */
+ private final Map<byte [], HColumnDescriptor> families =
new TreeMap<byte [], HColumnDescriptor>(Bytes.BYTES_RAWCOMPARATOR);
/**
- * Private constructor used internally creating table descriptors for
- * catalog tables: e.g. .META. and -ROOT-.
+ * <em> INTERNAL </em> Private constructor used internally creating table descriptors for
+ * catalog tables, <code>.META.</code> and <code>-ROOT-</code>.
*/
protected HTableDescriptor(final byte [] name, HColumnDescriptor[] families) {
this.name = name.clone();
@@ -126,8 +181,8 @@ public class HTableDescriptor implements
}
/**
- * Private constructor used internally creating table descriptors for
- * catalog tables: e.g. .META. and -ROOT-.
+ * <em> INTERNAL </em>Private constructor used internally creating table descriptors for
+ * catalog tables, <code>.META.</code> and <code>-ROOT-</code>.
*/
protected HTableDescriptor(final byte [] name, HColumnDescriptor[] families,
Map<ImmutableBytesWritable,ImmutableBytesWritable> values) {
@@ -143,9 +198,8 @@ public class HTableDescriptor implements
}
}
-
/**
- * Constructs an empty object.
+ * Default constructor which constructs an empty object.
* For deserializing an HTableDescriptor instance only.
* @see #HTableDescriptor(byte[])
*/
@@ -154,7 +208,7 @@ public class HTableDescriptor implements
}
/**
- * Constructor.
+ * Construct a table descriptor specifying table name.
* @param name Table name.
* @throws IllegalArgumentException if passed a table name
* that is made of other than 'word' characters, underscore or period: i.e.
@@ -166,8 +220,8 @@ public class HTableDescriptor implements
}
/**
- * Constructor.
- * @param name Table name.
+ * Construct a table descriptor specifying a byte array table name
+ * @param name - Table name as a byte array.
* @throws IllegalArgumentException if passed a table name
* that is made of other than 'word' characters, underscore or period: i.e.
* <code>[a-zA-Z_0-9-.].
@@ -181,7 +235,7 @@ public class HTableDescriptor implements
}
/**
- * Constructor.
+ * Construct a table descriptor by cloning the descriptor passed as a parameter.
* <p>
* Makes a deep copy of the supplied descriptor.
* Can make a modifiable descriptor from an UnmodifyableHTableDescriptor.
@@ -202,7 +256,9 @@ public class HTableDescriptor implements
}
/*
- * Set meta flags on this table.
+ * Set meta flags on this table.
+ * IS_ROOT_KEY is set if its a -ROOT- table
+ * IS_META_KEY is set either if its a -ROOT- or a .META. table
* Called by constructors.
* @param name
*/
@@ -212,7 +268,11 @@ public class HTableDescriptor implements
Bytes.equals(name, HConstants.META_TABLE_NAME));
}
- /** @return true if this is the root region */
+ /**
+ * Check if the descriptor represents a <code> -ROOT- </code> region.
+ *
+ * @return true if this is a <code> -ROOT- </code> region
+ */
public boolean isRootRegion() {
if (this.root == null) {
this.root = isSomething(IS_ROOT_KEY, false)? Boolean.TRUE: Boolean.FALSE;
@@ -220,13 +280,25 @@ public class HTableDescriptor implements
return this.root.booleanValue();
}
- /** @param isRoot true if this is the root region */
+ /**
+ * <em> INTERNAL </em> Used to denote if the current table represents
+ * <code> -ROOT- </code> region. This is used internally by the
+ * HTableDescriptor constructors
+ *
+ * @param isRoot true if this is the <code> -ROOT- </code> region
+ */
protected void setRootRegion(boolean isRoot) {
// TODO: Make the value a boolean rather than String of boolean.
values.put(IS_ROOT_KEY, isRoot? TRUE: FALSE);
}
- /** @return true if this is a meta region (part of the root or meta tables) */
+ /**
+ * Checks if this table is either <code> -ROOT- </code> or <code> .META. </code>
+ * region.
+ *
+ * @return true if this is either a <code> -ROOT- </code> or <code> .META. </code>
+ * region
+ */
public boolean isMetaRegion() {
if (this.meta == null) {
this.meta = calculateIsMetaRegion();
@@ -250,61 +322,73 @@ public class HTableDescriptor implements
}
/**
- * @param isMeta true if this is a meta region (part of the root or meta
- * tables) */
+ * <em> INTERNAL </em> Used to denote if the current table represents
+ * <code> -ROOT- </code> or <code> .META. </code> region. This is used
+ * internally by the HTableDescriptor constructors
+ *
+ * @param isMeta true if its either <code> -ROOT- </code> or
+ * <code> .META. </code> region
+ */
protected void setMetaRegion(boolean isMeta) {
values.put(IS_META_KEY, isMeta? TRUE: FALSE);
}
- /** @return true if table is a meta table, either <code>.META.</code> or
- * <code>-ROOT-</code>
+ /**
+ * Checks if the table is a <code>.META.</code> table
+ *
+ * @return true if table is <code> .META. </code> region.
*/
public boolean isMetaTable() {
return isMetaRegion() && !isRootRegion();
}
-
+
/**
- * @param n Table name.
- * @return True if a catalog table, -ROOT- or .META.
+ * Checks of the tableName being passed represents either
+ * <code > -ROOT- </code> or <code> .META. </code>
+ *
+ * @return true if a tablesName is either <code> -ROOT- </code>
+ * or <code> .META. </code>
*/
- public static boolean isMetaTable(final byte [] n) {
- return Bytes.equals(n, HConstants.ROOT_TABLE_NAME) ||
- Bytes.equals(n, HConstants.META_TABLE_NAME);
+ public static boolean isMetaTable(final byte [] tableName) {
+ return Bytes.equals(tableName, HConstants.ROOT_TABLE_NAME) ||
+ Bytes.equals(tableName, HConstants.META_TABLE_NAME);
}
/**
- * Check passed buffer is legal user-space table name.
- * @param b Table name.
- * @return Returns passed <code>b</code> param
- * @throws NullPointerException If passed <code>b</code> is null
- * @throws IllegalArgumentException if passed a table name
+ * Check passed byte buffer, "tableName", is legal user-space table name.
+ * @return Returns passed <code>tableName</code> param
+ * @throws NullPointerException If passed <code>tableName</code> is null
+ * @throws IllegalArgumentException if passed a tableName
* that is made of other than 'word' characters or underscores: i.e.
* <code>[a-zA-Z_0-9].
*/
- public static byte [] isLegalTableName(final byte [] b) {
- if (b == null || b.length <= 0) {
+ public static byte [] isLegalTableName(final byte [] tableName) {
+ if (tableName == null || tableName.length <= 0) {
throw new IllegalArgumentException("Name is null or empty");
}
- if (b[0] == '.' || b[0] == '-') {
- throw new IllegalArgumentException("Illegal first character <" + b[0] +
+ if (tableName[0] == '.' || tableName[0] == '-') {
+ throw new IllegalArgumentException("Illegal first character <" + tableName[0] +
"> at 0. User-space table names can only start with 'word " +
- "characters': i.e. [a-zA-Z_0-9]: " + Bytes.toString(b));
+ "characters': i.e. [a-zA-Z_0-9]: " + Bytes.toString(tableName));
}
- for (int i = 0; i < b.length; i++) {
- if (Character.isLetterOrDigit(b[i]) || b[i] == '_' || b[i] == '-' ||
- b[i] == '.') {
+ for (int i = 0; i < tableName.length; i++) {
+ if (Character.isLetterOrDigit(tableName[i]) || tableName[i] == '_' ||
+ tableName[i] == '-' || tableName[i] == '.') {
continue;
}
- throw new IllegalArgumentException("Illegal character <" + b[i] +
+ throw new IllegalArgumentException("Illegal character <" + tableName[i] +
"> at " + i + ". User-space table names can only contain " +
- "'word characters': i.e. [a-zA-Z_0-9-.]: " + Bytes.toString(b));
+ "'word characters': i.e. [a-zA-Z_0-9-.]: " + Bytes.toString(tableName));
}
- return b;
+ return tableName;
}
/**
+ * Getter for accessing the metadata associated with the key
+ *
* @param key The key.
* @return The value.
+ * @see #values
*/
public byte[] getValue(byte[] key) {
return getValue(new ImmutableBytesWritable(key));
@@ -318,8 +402,11 @@ public class HTableDescriptor implements
}
/**
+ * Getter for accessing the metadata associated with the key
+ *
* @param key The key.
- * @return The value as a string.
+ * @return The value.
+ * @see #values
*/
public String getValue(String key) {
byte[] value = getValue(Bytes.toBytes(key));
@@ -329,15 +416,21 @@ public class HTableDescriptor implements
}
/**
- * @return All values.
+ * Getter for fetching an unmodifiable {@link #values} map.
+ *
+ * @return unmodifiable map {@link #values}.
+ * @see #values
*/
public Map<ImmutableBytesWritable,ImmutableBytesWritable> getValues() {
return Collections.unmodifiableMap(values);
}
/**
+ * Setter for storing metadata as a (key, value) pair in {@link #values} map
+ *
* @param key The key.
* @param value The value.
+ * @see #values
*/
public void setValue(byte[] key, byte[] value) {
setValue(new ImmutableBytesWritable(key), value);
@@ -362,21 +455,30 @@ public class HTableDescriptor implements
}
/**
+ * Setter for storing metadata as a (key, value) pair in {@link #values} map
+ *
* @param key The key.
* @param value The value.
+ * @see #values
*/
public void setValue(String key, String value) {
setValue(Bytes.toBytes(key), Bytes.toBytes(value));
}
/**
- * @param key Key whose key and value we're to remove from HTD parameters.
+ * Remove metadata represented by the key from the {@link #values} map
+ *
+ * @param key Key whose key and value we're to remove from HTableDescriptor
+ * parameters.
*/
public void remove(final byte [] key) {
values.remove(new ImmutableBytesWritable(key));
}
/**
+ * Check if the readOnly flag of the table is set. If the readOnly flag is
+ * set then the contents of the table can only be read from but not modified.
+ *
* @return true if all columns in the table should be read only
*/
public boolean isReadOnly() {
@@ -384,6 +486,10 @@ public class HTableDescriptor implements
}
/**
+ * Setting the table as read only sets all the columns in the table as read
+ * only. By default all tables are modifiable, but if the readOnly flag is
+ * set to true then the contents of the table can only be read but not modified.
+ *
* @param readOnly True if all of the columns in the table should be read
* only.
*/
@@ -392,7 +498,11 @@ public class HTableDescriptor implements
}
/**
- * @return true if that table's log is hflush by other means
+ * Check if deferred log edits are enabled on the table.
+ *
+ * @return true if that deferred log flush is enabled on the table
+ *
+ * @see #setDeferredLogFlush(boolean)
*/
public synchronized boolean isDeferredLogFlush() {
if(this.isDeferredLog == null) {
@@ -403,49 +513,95 @@ public class HTableDescriptor implements
}
/**
- * @param isDeferredLogFlush true if that table's log is hlfush by oter means
- * only.
+ * This is used to defer the log edits syncing to the file system. Everytime
+ * an edit is sent to the server it is first sync'd to the file system by the
+ * log writer. This sync is an expensive operation and thus can be deferred so
+ * that the edits are kept in memory for a specified period of time as represented
+ * by <code> hbase.regionserver.optionallogflushinterval </code> and not flushed
+ * for every edit.
+ * <p>
+ * NOTE:- This option might result in data loss if the region server crashes
+ * before these deferred edits in memory are flushed onto the filesystem.
+ * </p>
+ *
+ * @param true if that deferred log flush is enabled on the table.
*/
public void setDeferredLogFlush(final boolean isDeferredLogFlush) {
setValue(DEFERRED_LOG_FLUSH_KEY, isDeferredLogFlush? TRUE: FALSE);
this.isDeferredLog = isDeferredLogFlush;
}
- /** @return name of table */
+ /**
+ * Get the name of the table as a byte array.
+ *
+ * @return name of table
+ */
public byte [] getName() {
return name;
}
- /** @return name of table */
+ /**
+ * Get the name of the table as a String
+ *
+ * @return name of table as a String
+ */
public String getNameAsString() {
return this.nameAsString;
}
-
- /** @return max hregion size for table */
- public long getMaxFileSize() {
- byte [] value = getValue(MAX_FILESIZE_KEY);
- if (value != null)
- return Long.valueOf(Bytes.toString(value)).longValue();
- return HConstants.DEFAULT_MAX_FILE_SIZE;
- }
/**
+ * This get the class associated with the region split policy which
+ * determines when a region split should occur. The class used by
+ * default is {@link ConstantSizeRegionSplitPolicy} which split the
+ * region base on a constant {@link #getMaxFileSize()}
+ *
* @return the class name of the region split policy for this table.
* If this returns null, the default constant size based split policy
* is used.
*/
- public String getRegionSplitPolicyClassName() {
+ public String getRegionSplitPolicyClassName() {
return getValue(SPLIT_POLICY);
}
- /** @param name name of table */
+ /**
+ * Set the name of the table.
+ *
+ * @param name name of table
+ */
public void setName(byte[] name) {
this.name = name;
this.nameAsString = Bytes.toString(this.name);
setMetaFlags(this.name);
}
+ /**
+ * Returns the maximum size upto which a region can grow to after which a region
+ * split is triggered. The region size is represented by the size of the biggest
+ * store file in that region.
+ *
+ * @return max hregion size for table
+ *
+ * @see #setMaxFileSize(long)
+ */
+ public long getMaxFileSize() {
+ byte [] value = getValue(MAX_FILESIZE_KEY);
+ if (value != null)
+ return Long.valueOf(Bytes.toString(value)).longValue();
+ return HConstants.DEFAULT_MAX_FILE_SIZE;
+ }
+
/**
+ * Sets the maximum size upto which a region can grow to after which a region
+ * split is triggered. The region size is represented by the size of the biggest
+ * store file in that region, i.e. If the biggest store file grows beyond the
+ * maxFileSize, then the region split is triggered. This defaults to a value of
+ * 256 MB.
+ * <p>
+ * This is not an absolute value and might vary. Assume that a single row exceeds
+ * the maxFileSize then the storeFileSize will be greater than maxFileSize since
+ * a single row cannot be split across multiple regions
+ * </p>
+ *
* @param maxFileSize The maximum file size that a store file can grow to
* before a split is triggered.
*/
@@ -454,7 +610,11 @@ public class HTableDescriptor implements
}
/**
+ * Returns the size of the memstore after which a flush to filesystem is triggered.
+ *
* @return memory cache flush size for each hregion
+ *
+ * @see #setMemStoreFlushSize(long)
*/
public long getMemStoreFlushSize() {
byte [] value = getValue(MEMSTORE_FLUSHSIZE_KEY);
@@ -464,6 +624,9 @@ public class HTableDescriptor implements
}
/**
+ * Represents the maximum size of the memstore after which the contents of the
+ * memstore are flushed to the filesystem. This defaults to a size of 64 MB.
+ *
* @param memstoreFlushSize memory cache flush size for each hregion
*/
public void setMemStoreFlushSize(long memstoreFlushSize) {
@@ -473,7 +636,7 @@ public class HTableDescriptor implements
/**
* Adds a column family.
- * @param family HColumnDescriptor of familyto add.
+ * @param family HColumnDescriptor of family to add.
*/
public void addFamily(final HColumnDescriptor family) {
if (family.getName() == null || family.getName().length <= 0) {
@@ -484,11 +647,11 @@ public class HTableDescriptor implements
/**
* Checks to see if this table contains the given column family
- * @param c Family name or column name.
+ * @param familyName Family name or column name.
* @return true if the table contains the specified family name
*/
- public boolean hasFamily(final byte [] c) {
- return families.containsKey(c);
+ public boolean hasFamily(final byte [] familyName) {
+ return families.containsKey(familyName);
}
/**
@@ -579,6 +742,12 @@ public class HTableDescriptor implements
}
/**
+ * Compare the contents of the descriptor with another one passed as a parameter.
+ * Checks if the obj passed is an instance of HTableDescriptor, if yes then the
+ * contents of the descriptors are compared.
+ *
+ * @return true if the contents of the the two descriptors exactly match
+ *
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
@@ -612,7 +781,10 @@ public class HTableDescriptor implements
}
// Writable
-
+ /**
+ * <em> INTERNAL </em> This method is a part of {@link WritableComparable} interface
+ * and is used for de-serialization of the HTableDescriptor over RPC
+ */
public void readFields(DataInput in) throws IOException {
int version = in.readInt();
if (version < 3)
@@ -643,6 +815,10 @@ public class HTableDescriptor implements
}
}
+ /**
+ * <em> INTERNAL </em> This method is a part of {@link WritableComparable} interface
+ * and is used for serialization of the HTableDescriptor over RPC
+ */
public void write(DataOutput out) throws IOException {
out.writeInt(TABLE_DESCRIPTOR_VERSION);
Bytes.writeByteArray(out, name);
@@ -664,6 +840,13 @@ public class HTableDescriptor implements
// Comparable
+ /**
+ * Compares the descriptor with another descriptor which is passed as a parameter.
+ * This compares the content of the two descriptors and not the reference.
+ *
+ * @return 0 if the contents of the descriptors are exactly matching,
+ * 1 if there is a mismatch in the contents
+ */
public int compareTo(final HTableDescriptor other) {
int result = Bytes.compareTo(this.name, other.name);
if (result == 0) {
@@ -694,40 +877,66 @@ public class HTableDescriptor implements
}
/**
- * @return Immutable sorted map of families.
+ * Returns an unmodifiable collection of all the {@link HColumnDescriptors}
+ * of all the column families of the table.
+ *
+ * @return Immutable collection of {@link HColumnDescriptor} of all the
+ * column families.
*/
public Collection<HColumnDescriptor> getFamilies() {
return Collections.unmodifiableCollection(this.families.values());
}
/**
+ * Returns all the column family names of the current table. The map of
+ * HTableDescriptor contains mapping of family name to HColumnDescriptors.
+ * This returns all the keys of the family map which represents the column
+ * family names of the table.
+ *
* @return Immutable sorted set of the keys of the families.
*/
public Set<byte[]> getFamiliesKeys() {
return Collections.unmodifiableSet(this.families.keySet());
}
+ /**
+ * Returns an array all the {@link HColumnDescriptor} of the column families
+ * of the table.
+ *
+ * @return Array of all the HColumnDescriptors of the current table
+ *
+ * @see #getFamilies()
+ */
public HColumnDescriptor[] getColumnFamilies() {
return getFamilies().toArray(new HColumnDescriptor[0]);
}
+
/**
- * @param column
+ * Returns the HColumnDescriptor for a specific column family with name as
+ * specified by the parameter column.
+ *
+ * @param column Column family name
* @return Column descriptor for the passed family name or the family on
* passed in column.
*/
public HColumnDescriptor getFamily(final byte [] column) {
return this.families.get(column);
}
+
/**
- * @param column
+ * Removes the HColumnDescriptor with name specified by the parameter column
+ * from the table descriptor
+ *
+ * @param column Name of the column family to be removed.
* @return Column descriptor for the passed family name or the family on
* passed in column.
*/
public HColumnDescriptor removeFamily(final byte [] column) {
return this.families.remove(column);
}
+
/**
* Add a table coprocessor to this table. The coprocessor
@@ -743,6 +952,7 @@ public class HTableDescriptor implements
addCoprocessor(className, null, Coprocessor.PRIORITY_USER, null);
}
+
/**
* Add a table coprocessor to this table. The coprocessor
* type must be {@link org.apache.hadoop.hbase.coprocessor.RegionObserver}
@@ -806,6 +1016,13 @@ public class HTableDescriptor implements
setValue(key, value);
}
+
+ /**
+ * Check if the table has an attached co-processor represented by the name className
+ *
+ * @param className - Class name of the co-processor
+ * @return true of the table has a co-processor className
+ */
public boolean hasCoprocessor(String className) {
Matcher keyMatcher;
Matcher valueMatcher;
@@ -832,10 +1049,14 @@ public class HTableDescriptor implements
return false;
}
+
/**
+ * Returns the {@link Path} object representing the table directory under
+ * path rootdir
+ *
* @param rootdir qualified path of HBase root directory
* @param tableName name of table
- * @return path for table
+ * @return {@link Path} for table
*/
public static Path getTableDir(Path rootdir, final byte [] tableName) {
return new Path(rootdir, Bytes.toString(tableName));
Modified: hbase/trunk/src/main/java/org/apache/hadoop/hbase/master/MasterFileSystem.java
URL: http://svn.apache.org/viewvc/hbase/trunk/src/main/java/org/apache/hadoop/hbase/master/MasterFileSystem.java?rev=1186559&r1=1186558&r2=1186559&view=diff
==============================================================================
--- hbase/trunk/src/main/java/org/apache/hadoop/hbase/master/MasterFileSystem.java (original)
+++ hbase/trunk/src/main/java/org/apache/hadoop/hbase/master/MasterFileSystem.java Wed Oct 19 23:13:20 2011
@@ -372,7 +372,7 @@ public class MasterFileSystem {
private static void setInfoFamilyCachingForRoot(final boolean b) {
for (HColumnDescriptor hcd:
- HTableDescriptor.ROOT_TABLEDESC.families.values()) {
+ HTableDescriptor.ROOT_TABLEDESC.getColumnFamilies()) {
if (Bytes.equals(hcd.getName(), HConstants.CATALOG_FAMILY)) {
hcd.setBlockCacheEnabled(b);
hcd.setInMemory(b);
@@ -382,7 +382,7 @@ public class MasterFileSystem {
private static void setInfoFamilyCachingForMeta(final boolean b) {
for (HColumnDescriptor hcd:
- HTableDescriptor.META_TABLEDESC.families.values()) {
+ HTableDescriptor.META_TABLEDESC.getColumnFamilies()) {
if (Bytes.equals(hcd.getName(), HConstants.CATALOG_FAMILY)) {
hcd.setBlockCacheEnabled(b);
hcd.setInMemory(b);