HDFS-4377. Some trivial DN comment cleanup. Contributed by Eli Collins
git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1431754 13f79535-47bb-0310-9956-ffa450edef68
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Eli Collins
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4774c6a5b8
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@ -186,6 +186,8 @@ Release 2.0.3-alpha - Unreleased
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HDFS-4363. Combine PBHelper and HdfsProtoUtil and remove redundant
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methods. (suresh)
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HDFS-4377. Some trivial DN comment cleanup. (eli)
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OPTIMIZATIONS
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BUG FIXES
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@ -171,20 +171,19 @@ public class BlockManager {
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*/
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private final Set<Block> postponedMisreplicatedBlocks = Sets.newHashSet();
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//
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// Keeps a TreeSet for every named node. Each treeset contains
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// a list of the blocks that are "extra" at that location. We'll
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// eventually remove these extras.
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// Mapping: StorageID -> TreeSet<Block>
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//
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/**
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* Maps a StorageID to the set of blocks that are "extra" for this
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* DataNode. We'll eventually remove these extras.
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*/
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public final Map<String, LightWeightLinkedSet<Block>> excessReplicateMap =
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new TreeMap<String, LightWeightLinkedSet<Block>>();
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//
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// Store set of Blocks that need to be replicated 1 or more times.
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// We also store pending replication-orders.
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//
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/**
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* Store set of Blocks that need to be replicated 1 or more times.
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* We also store pending replication-orders.
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*/
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public final UnderReplicatedBlocks neededReplications = new UnderReplicatedBlocks();
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@VisibleForTesting
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final PendingReplicationBlocks pendingReplications;
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@ -970,29 +970,27 @@ public class DataNode extends Configured
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dnId.setStorageID(createNewStorageId(dnId.getXferPort()));
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}
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/**
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* @return a unique storage ID of form "DS-randInt-ipaddr-port-timestamp"
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*/
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static String createNewStorageId(int port) {
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/* Return
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* "DS-randInt-ipaddr-currentTimeMillis"
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* It is considered extermely rare for all these numbers to match
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* on a different machine accidentally for the following
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* a) SecureRandom(INT_MAX) is pretty much random (1 in 2 billion), and
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* b) Good chance ip address would be different, and
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* c) Even on the same machine, Datanode is designed to use different ports.
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* d) Good chance that these are started at different times.
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* For a confict to occur all the 4 above have to match!.
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* The format of this string can be changed anytime in future without
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* affecting its functionality.
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*/
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// It is unlikely that we will create a non-unique storage ID
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// for the following reasons:
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// a) SecureRandom is a cryptographically strong random number generator
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// b) IP addresses will likely differ on different hosts
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// c) DataNode xfer ports will differ on the same host
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// d) StorageIDs will likely be generated at different times (in ms)
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// A conflict requires that all four conditions are violated.
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// NB: The format of this string can be changed in the future without
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// requiring that old SotrageIDs be updated.
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String ip = "unknownIP";
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try {
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ip = DNS.getDefaultIP("default");
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} catch (UnknownHostException ignored) {
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LOG.warn("Could not find ip address of \"default\" inteface.");
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LOG.warn("Could not find an IP address for the \"default\" inteface.");
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}
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int rand = DFSUtil.getSecureRandom().nextInt(Integer.MAX_VALUE);
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return "DS-" + rand + "-" + ip + "-" + port + "-"
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+ Time.now();
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return "DS-" + rand + "-" + ip + "-" + port + "-" + Time.now();
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}
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/** Ensure the authentication method is kerberos */
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@ -62,7 +62,7 @@ import org.apache.hadoop.util.DiskChecker;
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*/
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@InterfaceAudience.Private
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public class DataStorage extends Storage {
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// Constants
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public final static String BLOCK_SUBDIR_PREFIX = "subdir";
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final static String BLOCK_FILE_PREFIX = "blk_";
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final static String COPY_FILE_PREFIX = "dncp_";
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@ -71,13 +71,13 @@ public class DataStorage extends Storage {
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public final static String STORAGE_DIR_FINALIZED = "finalized";
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public final static String STORAGE_DIR_TMP = "tmp";
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/** Access to this variable is guarded by "this" */
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/** Unique storage ID. {@see DataNode#createNewStorageId(int)} for details */
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private String storageID;
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// flag to ensure initialzing storage occurs only once
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private boolean initilized = false;
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// Flag to ensure we only initialize storage once
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private boolean initialized = false;
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// BlockPoolStorage is map of <Block pool Id, BlockPoolStorage>
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// Maps block pool IDs to block pool storage
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private Map<String, BlockPoolSliceStorage> bpStorageMap
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= Collections.synchronizedMap(new HashMap<String, BlockPoolSliceStorage>());
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@ -130,7 +130,7 @@ public class DataStorage extends Storage {
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synchronized void recoverTransitionRead(DataNode datanode,
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NamespaceInfo nsInfo, Collection<File> dataDirs, StartupOption startOpt)
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throws IOException {
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if (initilized) {
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if (initialized) {
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// DN storage has been initialized, no need to do anything
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return;
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}
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@ -200,7 +200,7 @@ public class DataStorage extends Storage {
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this.writeAll();
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// 4. mark DN storage is initilized
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this.initilized = true;
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this.initialized = true;
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}
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/**
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