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Posted to common-commits@hadoop.apache.org by in...@apache.org on 2019/09/24 16:54:19 UTC
[hadoop] branch trunk updated: HDFS-14837. Review of Block.java.
Contributed by David Mollitor.
This is an automated email from the ASF dual-hosted git repository.
inigoiri pushed a commit to branch trunk
in repository https://gitbox.apache.org/repos/asf/hadoop.git
The following commit(s) were added to refs/heads/trunk by this push:
new 816d3cb HDFS-14837. Review of Block.java. Contributed by David Mollitor.
816d3cb is described below
commit 816d3cb9087c9406cc0b16bd80009562ffc7d4b3
Author: Inigo Goiri <in...@apache.org>
AuthorDate: Tue Sep 24 09:54:09 2019 -0700
HDFS-14837. Review of Block.java. Contributed by David Mollitor.
---
.../org/apache/hadoop/hdfs/protocol/Block.java | 141 +++++++++++++++------
1 file changed, 101 insertions(+), 40 deletions(-)
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/Block.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/Block.java
index 4128ece..0a41254 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/Block.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/Block.java
@@ -17,21 +17,32 @@
*/
package org.apache.hadoop.hdfs.protocol;
-import java.io.*;
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.File;
+import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
+import javax.annotation.Nonnull;
+
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
-import org.apache.hadoop.io.*;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.WritableFactories;
+import org.apache.hadoop.io.WritableFactory;
-import javax.annotation.Nonnull;
-
-/**************************************************
- * A Block is a Hadoop FS primitive, identified by a
- * long.
+/**
+ * A Block is a Hadoop FS primitive, identified by its block ID (a long). A
+ * block also has an accompanying generation stamp. A generation stamp is a
+ * monotonically increasing 8-byte number for each block that is maintained
+ * persistently by the NameNode. However, for the purposes of this class, two
+ * Blocks are considered equal iff they have the same block ID.
*
- **************************************************/
+ * @see Block#equals(Object)
+ * @see Block#hashCode()
+ * @see Block#compareTo(Block)
+ */
@InterfaceAudience.Private
@InterfaceStability.Evolving
public class Block implements Writable, Comparable<Block> {
@@ -119,8 +130,7 @@ public class Block implements Writable, Comparable<Block> {
this.numBytes = len;
this.generationStamp = genStamp;
}
- /**
- */
+
public long getBlockId() {
return blockId;
}
@@ -130,17 +140,21 @@ public class Block implements Writable, Comparable<Block> {
}
/**
+ * Get the block name. The format of the name is in the format:
+ * <p>
+ * blk_1, blk_2, blk_3, etc.
+ * </p>
+ *
+ * @return the block name
*/
public String getBlockName() {
- return new StringBuilder().append(BLOCK_FILE_PREFIX)
- .append(blockId).toString();
+ return BLOCK_FILE_PREFIX + blockId;
}
- /**
- */
public long getNumBytes() {
return numBytes;
}
+
public void setNumBytes(long len) {
this.numBytes = len;
}
@@ -161,28 +175,33 @@ public class Block implements Writable, Comparable<Block> {
* @return the string representation of the block
*/
public static String toString(final Block b) {
- StringBuilder sb = new StringBuilder();
- sb.append(BLOCK_FILE_PREFIX).
- append(b.blockId).append("_").
- append(b.generationStamp);
- return sb.toString();
+ return new StringBuilder(BLOCK_FILE_PREFIX)
+ .append(b.blockId)
+ .append('_')
+ .append(b.generationStamp)
+ .toString();
}
/**
+ * Get the block name. The format of the name is in the format:
+ * <p>
+ * blk_block-id_generation, blk_1_1, blk_1_2, blk_2_1, etc.
+ * </p>
+ *
+ * @return the full block name
*/
@Override
public String toString() {
- return toString(this);
+ return Block.toString(this);
}
public void appendStringTo(StringBuilder sb) {
sb.append(BLOCK_FILE_PREFIX)
.append(blockId)
- .append("_")
+ .append('_')
.append(getGenerationStamp());
}
-
/////////////////////////////////////
// Writable
/////////////////////////////////////
@@ -223,32 +242,74 @@ public class Block implements Writable, Comparable<Block> {
this.generationStamp = in.readLong();
}
- @Override // Comparable
+ /**
+ * Compares this Block with the specified Block for order. Returns a negative
+ * integer, zero, or a positive integer as this Block is less than, equal to,
+ * or greater than the specified Block. Blocks are ordered based on their
+ * block ID.
+ *
+ * @param b the Block to be compared
+ * @return a negative integer, zero, or a positive integer as this Block is
+ * less than, equal to, or greater than the specified Block.
+ */
+ @Override
public int compareTo(@Nonnull Block b) {
- return blockId < b.blockId ? -1 :
- blockId > b.blockId ? 1 : 0;
+ return Long.compare(blockId, b.blockId);
}
- @Override // Object
- public boolean equals(Object o) {
- return this == o || o instanceof Block && compareTo((Block) o) == 0;
+ /**
+ * Indicates whether some Block is "equal to" this one. Two blocks are
+ * considered equal if they have the same block ID.
+ *
+ * @param obj the reference object with which to compare.
+ * @return true if this Block is the same as the argument; false otherwise.
+ */
+ @Override
+ public boolean equals(Object obj) {
+ if (this == obj) {
+ return true;
+ }
+ if (!(obj instanceof Block)) {
+ return false;
+ }
+ Block other = (Block) obj;
+ return (blockId == other.blockId);
}
/**
- * @return true if the two blocks have the same block ID and the same
- * generation stamp, or if both blocks are null.
+ * Returns a hash code value for the Block. The hash code adheres to the
+ * general contract of hashCode. If two Blocks are equal according to the
+ * equals(Object) method, then calling the hashCode method on each of the two
+ * blocks produce the same integer result.
+ *
+ * @return a hash code value for this block
+ * @see Block#equals(Object)
*/
- public static boolean matchingIdAndGenStamp(Block a, Block b) {
- if (a == b) return true; // same block, or both null
- // only one null
- return !(a == null || b == null) &&
- a.blockId == b.blockId &&
- a.generationStamp == b.generationStamp;
+ @Override
+ public int hashCode() {
+ return Long.hashCode(blockId);
}
- @Override // Object
- public int hashCode() {
- //GenerationStamp is IRRELEVANT and should not be used here
- return (int)(blockId^(blockId>>>32));
+ /**
+ * A helper function to determine if two blocks are equal, based on the block
+ * ID and the generation stamp. This is a different equalities check than the
+ * default behavior of the Block class. Two blocks are considered equal by
+ * this function iff the two blocks have the same block ID and the same
+ * generation stamp, or if both blocks are null.
+ *
+ * @param a an object
+ * @param b an object to be compared with {@code a} for equality
+ * @return {@code true} if the blocks are deeply equal to each other and
+ * {@code false} otherwise
+ * @see Block
+ */
+ public static boolean matchingIdAndGenStamp(Block a, Block b) {
+ if (a == b) {
+ return true;
+ } else if (a == null || b == null) {
+ return false;
+ } else {
+ return a.blockId == b.blockId && a.generationStamp == b.generationStamp;
+ }
}
}
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