com.bigdata.htree.HTree Maven / Gradle / Ivy
/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
[email protected]
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on Apr 19, 2011
*/
package com.bigdata.htree;
import java.lang.ref.Reference;
import java.lang.ref.WeakReference;
import java.lang.reflect.Constructor;
import java.util.Arrays;
import java.util.NoSuchElementException;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.locks.Lock;
import org.apache.log4j.Logger;
import com.bigdata.BigdataStatics;
import com.bigdata.btree.AbstractBTree;
import com.bigdata.btree.AbstractNode;
import com.bigdata.btree.BTree;
import com.bigdata.btree.BTreeCounters;
import com.bigdata.btree.BaseIndexStats;
import com.bigdata.btree.Checkpoint;
import com.bigdata.btree.HTreeIndexMetadata;
import com.bigdata.btree.ICounter;
import com.bigdata.btree.IDirtyListener;
import com.bigdata.btree.IIndexLocalCounter;
import com.bigdata.btree.ITuple;
import com.bigdata.btree.ITupleIterator;
import com.bigdata.btree.IndexMetadata;
import com.bigdata.btree.IndexTypeEnum;
import com.bigdata.btree.Leaf;
import com.bigdata.btree.Node;
import com.bigdata.btree.ReadOnlyCounter;
import com.bigdata.btree.keys.IKeyBuilder;
import com.bigdata.io.ByteArrayBuffer;
import com.bigdata.io.SerializerUtil;
import com.bigdata.mdi.LocalPartitionMetadata;
import com.bigdata.rawstore.IRawStore;
import com.bigdata.util.Bytes;
import com.bigdata.util.BytesUtil;
/**
* An mutable persistence capable extensible hash tree.
*
* @author Bryan Thompson
*
* @see
* A Robust Scheme for Multilevel Extendible Hashing by Sven Helmer,
* Thomas Neumann, Guido Moerkotte. ISCIS 2003: 220-227.
*
* TODO It should be possible to define an native int32 hash table in
* parallel to the unsigned byte[] hash table simply by having an
* alternative descent passing an int32 key all the way down and using the
* variant of getBits() method which operates on the int32 values. We could
* also optimize the storage and retrieval of the int32 keys, perhaps with
* a custom mutable bucket page and mutable bucket data implementation for
* int32 keys. This optimization is likely to be quite worth while as the
* majority of use cases for the hash tree use int32 keys.
*
* TODO It is quite possible to define a range query interface for the hash
* tree. You have to use an order preserving hash function, which is
* external to the HTree implementation. Internally, the HTree must either
* double-link the pages or crawl the directory structure.
*
* TODO The keys should be declared as a computed key based on the data
* fields in the record. The {@link HTree} supports arbitrary bit length
* keys, but can be optimized for int32 keys easily enough.
*
* TODO Instrument performance counters for structural modifications,
* insert, remove, etc. per {@link BTreeCounters}.
*/
public class HTree extends AbstractHTree
implements
IIndexLocalCounter
// ICheckpointProtocol // interface declaration moved to subclass
// IIndex,
// ISimpleBTree//, IAutoboxBTree, ILinearList, IBTreeStatistics, ILocalBTreeView
// IRangeQuery
{
// private static final transient Logger log = Logger.getLogger(HTree.class);
/**
* The #of bits of distinction to be made each time we split a directory
* page in the {@link HTree}. See
* {@link #splitDirectoryPage(DirectoryPage, int, AbstractPage)} for a write
* up on this.
*/
/*private*/ final int splitBits = 1; // in [1:addressBits];
/*
* metadata about the index.
*
* @todo this data should be rolled into the IndexMetadata object.
*/
final boolean versionTimestamps = false;
final boolean deleteMarkers = false;
final boolean rawRecords;
/**
* The #of {@link DirectoryPage} in the {@link HTree}. This is ONE (1) for a
* new {@link HTree}.
*/
protected long nnodes;
/**
* The #of {@link BucketPage}s in the {@link HTree}. This is one (1) for a
* new {@link HTree} (one directory page and one bucket page).
*/
protected long nleaves;
/**
* The #of entries in the {@link HTree}. This is ZERO (0) for a new
* {@link HTree}.
*/
protected long nentries;
/**
* The value of the record version number that will be assigned to the next
* node or leaf written onto the backing store. This number is incremented
* each time a node or leaf is written onto the backing store. The initial
* value is ZERO (0). The first value assigned to a node or leaf will be
* ZERO (0).
*/
protected long recordVersion;
/**
* The mutable counter exposed by #getCounter()}.
*
* Note: This is protected so that it will be visible to
* {@link Checkpoint} which needs to write the actual value store in this
* counter into its serialized record (without the partition identifier).
*/
protected AtomicLong counter;
/**
* A buffer used to encode a raw record address for a mutable {@link BTree}
* and otherwise null.
*/
private final ByteArrayBuffer recordAddrBuf;
@Override
final public long getNodeCount() {
return nnodes;
}
@Override
final public long getLeafCount() {
return nleaves;
}
@Override
final public long getEntryCount() {
return nentries;
}
/**
* The constructor sets this field initially based on a {@link Checkpoint}
* record containing the only address of the {@link IndexMetadata} for the
* index. Thereafter this reference is maintained as the {@link Checkpoint}
* record last written by {@link #writeCheckpoint()} or read by
* {@link #load(IRawStore, long)}.
*/
private Checkpoint checkpoint = null;
@Override
final public Checkpoint getCheckpoint() {
if (checkpoint == null)
throw new AssertionError();
return checkpoint;
}
@Override
final public long getRecordVersion() {
return recordVersion;
}
@Override
final public long getMetadataAddr() {
return metadata.getMetadataAddr();
}
@Override
final public long getRootAddr() {
return (root == null ? getCheckpoint().getRootAddr() : root
.getIdentity());
}
/**
* Return true iff changes would be lost unless the B+Tree is flushed to the
* backing store using {@link #writeCheckpoint()}.
*
* Note: In order to avoid needless checkpoints this method will return
* false if:
*
* - the metadata record is persistent -AND-
*
* - EITHER the root is
null, indicating that the index
* is closed (in which case there are no buffered writes);
* - OR the root of the btree is NOT dirty, the persistent address of the
* root of the btree agrees with {@link Checkpoint#getRootAddr()}, and the
* {@link #counter} value agrees {@link Checkpoint#getCounter()}.
*
*
*
*
* @return true true iff changes would be lost unless the
* B+Tree was flushed to the backing store using
* {@link #writeCheckpoint()}.
*/
public boolean needsCheckpoint() {
if(!checkpoint.hasCheckpointAddr()) {
/*
* The checkpoint record needs to be written.
*/
return true;
}
if(metadata.getMetadataAddr() == 0L) {
/*
* The index metadata record was replaced and has not yet been
* written onto the store.
*/
return true;
}
if(metadata.getMetadataAddr() != checkpoint.getMetadataAddr()) {
/*
* The index metadata record was replaced and has been written on
* the store but the checkpoint record does not reflect the new
* address yet.
*/
return true;
}
if(checkpoint.getCounter() != counter.get()) {
// The counter has been modified.
return true;
}
if(root != null ) {
if (root.isDirty()) {
// The root node is dirty.
return true;
}
if(checkpoint.getRootAddr() != root.getIdentity()) {
// The root node has a different persistent identity.
return true;
}
}
/*
* No apparent change in persistent state so we do NOT need to do a
* checkpoint.
*/
return false;
// if (metadata.getMetadataAddr() != 0L && //
// (root == null || //
// ( !root.dirty //
// && checkpoint.getRootAddr() == root.identity //
// && checkpoint.getCounter() == counter.get())
// )
// ) {
//
// return false;
//
// }
//
// return true;
}
/**
* Method updates the index metadata associated with this {@link BTree}.
* The new metadata record will be written out as part of the next index
* {@link #writeCheckpoint()}.
*
* Note: this method should be used with caution.
*
* @param indexMetadata
* The new metadata description for the {@link BTree}.
*
* @throws IllegalArgumentException
* if the new value is null
* @throws IllegalArgumentException
* if the new {@link IndexMetadata} record has already been
* written on the store - see
* {@link IndexMetadata#getMetadataAddr()}
* @throws UnsupportedOperationException
* if the index is read-only.
*/
final public void setIndexMetadata(final HTreeIndexMetadata indexMetadata) {
assertNotReadOnly();
if (indexMetadata == null)
throw new IllegalArgumentException();
if (indexMetadata.getMetadataAddr() != 0)
throw new IllegalArgumentException();
this.metadata = indexMetadata;
// gets us on the commit list for Name2Addr.
fireDirtyEvent();
}
// /**
// * Handle request for a commit by {@link #writeCheckpoint()}ing dirty nodes
// * and leaves onto the store, writing a new metadata record, and returning
// * the address of that metadata record.
// *
// * Note: In order to avoid needless writes the existing metadata record is
// * always returned if {@link #needsCheckpoint()} is false.
// *
// * Note: The address of the existing {@link Checkpoint} record is always
// * returned if {@link #getAutoCommit() autoCommit} is disabled.
// *
// * @return The address of a {@link Checkpoint} record from which the btree
// * may be reloaded.
// */
public long handleCommit(final long commitTime) {
return writeCheckpoint2().getCheckpointAddr();
}
/**
* Returns an {@link ICounter}. The {@link ICounter} is mutable iff the
* {@link BTree} is mutable. All {@link ICounter}s returned by this method
* report and increment the same underlying counter.
*
* Note: When the {@link BTree} is part of a scale-out index then the
* counter will assign values within a namespace defined by the partition
* identifier.
*/
public ICounter getCounter() {
ICounter counter = new Counter(this);
final LocalPartitionMetadata pmd = metadata.getPartitionMetadata();
if (pmd != null) {
throw new UnsupportedOperationException();
// counter = new PartitionedCounter(pmd.getPartitionId(), counter);
}
if (isReadOnly()) {
return new ReadOnlyCounter(counter);
}
return counter;
}
/**
* Required constructor form for {@link HTree} and any derived subclasses.
* This constructor is used both to create a new {@link HTree}, and to load
* a {@link HTree} from the store using a {@link Checkpoint} record.
*
* @param store
* The store.
* @param checkpoint
* A {@link Checkpoint} record for that {@link HTree}.
* @param metadata
* The metadata record for that {@link HTree}.
* @param readOnly
* When true the {@link HTree} will be immutable.
*
* @see HTree#create(IRawStore, IndexMetadata)
* @see HTree#load(IRawStore, long, boolean)
*/
// * @throws IllegalArgumentException
// * if addressBits is LT ONE (1).
// * @throws IllegalArgumentException
// * if addressBits is GT (16) (fan out of 65536).
public HTree(final IRawStore store, final Checkpoint checkpoint,
final IndexMetadata metadata, final boolean readOnly) {
super( store,
NodeFactory.INSTANCE, //
readOnly, // read-only
(HTreeIndexMetadata)metadata,//
metadata.getBtreeRecordCompressorFactory()
);
// this.readOnly = readOnly;
if (checkpoint == null) {
throw new IllegalArgumentException();
}
if (store != null) {
if (checkpoint.getMetadataAddr() != metadata.getMetadataAddr()) {
// must agree.
throw new IllegalArgumentException();
}
}
if (metadata.getConflictResolver() != null && !metadata.isIsolatable()) {
throw new IllegalArgumentException(
"Conflict resolver may only be used with isolatable indices");
}
setCheckpoint(checkpoint);
// // save the address from which the index metadata record was read.
// this.lastMetadataAddr = metadata.getMetadataAddr();
/*
* Note: the mutable BTree has a limit here so that split() will always
* succeed. That limit does not apply for an immutable btree.
*/
assert readOnly || writeRetentionQueue.capacity() >= IndexMetadata.Options.MIN_WRITE_RETENTION_QUEUE_CAPACITY;
/*
* Note: Re-open is deferred so that we can mark the BTree as read-only
* before we read the root node.
*/
// reopen();
/*
* Buffer used to encode addresses into the tuple value for a mutable
* B+Tree.
*/
recordAddrBuf = readOnly ? null
: new ByteArrayBuffer(Bytes.SIZEOF_LONG);
this.rawRecords = metadata.getRawRecords();
}
/**
* Encode a raw record address into a byte[] suitable for storing in the
* value associated with a tuple and decoding using
* {@link AbstractBTree#decodeRecordAddr(byte[])}. This method is only
* supported for a mutable {@link BTree} instance. Per the contract of the
* mutable {@link BTree}, it is not thread-safe.
*
* @param addr
* The raw record address.
*
* @return A newly allocated byte[] which encodes that address.
*/
byte[] encodeRecordAddr(final long addr) {
return AbstractBTree.encodeRecordAddr(recordAddrBuf, addr);
}
/**
* Sets the {@link #checkpoint} and initializes the mutable fields from the
* checkpoint record. In order for this operation to be atomic, the caller
* must be synchronized on the {@link HTree} or otherwise guaranteed to have
* exclusive access, e.g., during the ctor or when the {@link HTree} is
* mutable and access is therefore required to be single-threaded.
*/
protected void setCheckpoint(final Checkpoint checkpoint) {
this.checkpoint = checkpoint; // save reference.
// Note: Height is not uniform for an HTree.
// this.height = checkpoint.getHeight();
this.nnodes = checkpoint.getNodeCount();
this.nleaves = checkpoint.getLeafCount();
this.nentries = checkpoint.getEntryCount();
this.counter = new AtomicLong( checkpoint.getCounter() );
this.recordVersion = checkpoint.getRecordVersion();
}
/**
* Creates and sets new root {@link Leaf} on the B+Tree and (re)sets the
* various counters to be consistent with that root. This is used both
* by the constructor for a new {@link BTree} and by {@link #removeAll()}.
*
* Note: The {@link #getCounter()} is NOT changed by this method.
*/
final private void newRoot() {
// height = 0;
nnodes = 0;
nentries = 0;
final boolean wasDirty = root != null && root.isDirty();
nleaves = 0;
/*
* The initial setup of the hash tree is a root directory page whose
* global depth is the #of address bits (which is the maximum value that
* global depth can take on for a given hash tree). There is a single
* bucket page and all entries in the root directory page point to that
* bucket. This means that the local depth of the initial bucket page
* will be zero (you can prove this for yourself by consulting the
* tables generated by TestHTree). With a depth of zero, the initial
* bucket page will have buddy hash buckets which can hold only a single
* distinct hash key (buckets always have to handle duplicates of a hash
* key).
*
* From this initial configuration, inserts of 2 distinct keys which
* fall into the same buddy hash tables will cause that buddy hash
* buckets in the initial bucket page to split, increasing the depth of
* the resulting bucket page by one. Additional splits driven by inserts
* of distinct keys will eventually cause the local depth of some bucket
* page to exceed the global depth of the root and a new level will be
* introduced below the root. The hash tree can continue to grow in this
* manner, gradually adding depth where there are bit prefixes for which
* there exists a lot of variety in the observed keys.
*/
// Initial root.
final DirectoryPage r = new DirectoryPage(//
this,// the owning htree instance
null, // overflowKey
addressBits // the global depth of the root.
);
nnodes++;
assert r.getSlotsPerBuddy() == (1 << addressBits) : "slotsPerBuddy="
+ r.getSlotsPerBuddy();
assert r.getNumBuddies() == 1 : "numBuddies=" + r.getNumBuddies();
// Data for the root.
final MutableDirectoryPageData rdata = (MutableDirectoryPageData) r.data;
// Initial bucket.
final BucketPage b = new BucketPage(this, 0/* globalDepth */);
nleaves++;
final int nslots = r.getSlotsPerBuddy() * r.getNumBuddies();
for (int i = 0; i < nslots; i++) {
b.parent = (Reference) r.self;
r.childRefs[i] = (Reference) b.self;
rdata.childAddr[i] = 0L;
}
this.root = r;
// Note: Counter is unchanged!
// counter = new AtomicLong( 0L );
// TODO support bloom filter?
// if (metadata.getBloomFilterFactory() != null) {
//
// /*
// * Note: Allocate a new bloom filter since the btree is now empty
// * and set its reference on the BTree. We need to do this here in
// * order to (a) overwrite the old reference when we are replacing
// * the root, e.g., for removeAll(); and (b) to make sure that the
// * bloomFilter reference is defined since the checkpoint will not
// * have its address until the next time we call writeCheckpoint()
// * and therefore readBloomFilter() would fail if we did not create
// * and assign the bloom filter here.
// */
//
// bloomFilter = metadata.getBloomFilterFactory().newBloomFilter();
//
// }
/*
* Note: a new root leaf is created when an empty btree is (re-)opened.
* However, if the BTree is marked as read-only then do not fire off a
* dirty event.
*/
if(!wasDirty && !readOnly) {
fireDirtyEvent();
}
}
@Override
protected void _reopen() {
if (checkpoint.getRootAddr() == 0L) {
/*
* Create the root leaf.
*
* Note: if there is an optional bloom filter, then it is created
* now.
*/
newRoot();
} else {
/*
* Read the root node of the HTree and set its depth, which is
* always [addressBits].
*/
root = (DirectoryPage) readNodeOrLeaf(checkpoint.getRootAddr());
root.globalDepth = addressBits;
// Note: The optional bloom filter will be read lazily.
}
}
final public long getLastCommitTime() {
return lastCommitTime;
}
final public long getRevisionTimestamp() {
if (readOnly)
throw new UnsupportedOperationException(ERROR_READ_ONLY);
return lastCommitTime + 1;
}
@Override
final public void setLastCommitTime(final long lastCommitTime) {
if (lastCommitTime == 0L)
throw new IllegalArgumentException();
if (this.lastCommitTime == lastCommitTime) {
// No change.
return;
}
if (INFO)
log.info("old=" + this.lastCommitTime + ", new=" + lastCommitTime);
// Note: Commented out to allow replay of historical transactions.
/*if (this.lastCommitTime != 0L && this.lastCommitTime > lastCommitTime) {
throw new IllegalStateException("Updated lastCommitTime: old="
+ this.lastCommitTime + ", new=" + lastCommitTime);
}*/
this.lastCommitTime = lastCommitTime;
}
/**
* The lastCommitTime of the {@link Checkpoint} record from which the
* {@link BTree} was loaded.
*
* Note: Made volatile on 8/2/2010 since it is not otherwise obvious what
* would guarantee visibility of this field, through I do seem to remember
* that visibility might be guaranteed by how the BTree class is discovered
* and returned to the class. Still, it does no harm to make this a volatile
* read.
*/
volatile private long lastCommitTime = 0L;// Until the first commit.
final public IDirtyListener getDirtyListener() {
return listener;
}
final public void setDirtyListener(final IDirtyListener listener) {
assertNotReadOnly();
this.listener = listener;
}
private IDirtyListener listener;
/**
* Fire an event to the listener (iff set).
*/
final protected void fireDirtyEvent() {
assertNotReadOnly();
final IDirtyListener l = this.listener;
if (l == null)
return;
if (Thread.interrupted()) {
throw new RuntimeException(new InterruptedException());
}
l.dirtyEvent(this);
}
/**
* Flush the nodes of the {@link BTree} to the backing store. After invoking
* this method the root of the {@link BTree} will be clean.
*
* Note: This does NOT flush all persistent state. See
* {@link #writeCheckpoint()} which also handles the optional bloom filter,
* the {@link IndexMetadata}, and the {@link Checkpoint} record itself.
*
* @return true if anything was written.
*/
final public boolean flush() {
assertNotTransient();
assertNotReadOnly();
if (root != null && root.isDirty()) {
writeNodeRecursive(root);
if(INFO)
log.info("flushed root: addr=" + root.getIdentity());
return true;
}
return false;
}
/**
* Returns an immutable view of this {@link HTree}. If {@link BTree} is
* already read-only, then this instance is returned. Otherwise, a
* read-only {@link BTree} is loaded from the last checkpoint and returned.
*
* @throws IllegalStateException
* If the {@link BTree} is dirty.
*
* @todo The {@link Checkpoint} could hold a {@link WeakReference} singleton
* to the read-only view loaded from that checkpoint.
*/
public HTree asReadOnly() {
if (isReadOnly()) {
return this;
}
if(needsCheckpoint())
throw new IllegalStateException();
return HTree
.load(store, checkpoint.getCheckpointAddr(), true/* readOnly */);
}
// * Checkpoint operation {@link #flush()}es dirty nodes, the optional
// * {@link IBloomFilter} (if dirty), the {@link IndexMetadata} (if dirty),
// * and then writes a new {@link Checkpoint} record on the backing store,
// * saves a reference to the current {@link Checkpoint} and returns the
// * address of that {@link Checkpoint} record.
// *
// * Note: A checkpoint by itself is NOT an atomic commit. The commit protocol
// * is at the store level and uses {@link Checkpoint}s to ensure that the
// * state of the {@link BTree} is current on the backing store.
// *
// * @return The address at which the {@link Checkpoint} record for the
// * {@link BTree} was written onto the store. The {@link BTree} can
// * be reloaded from this {@link Checkpoint} record.
// *
// * @see #writeCheckpoint2(), which returns the {@link Checkpoint} record
// * itself.
/**
* {@inheritDoc}
*
* @see #load(IRawStore, long)
*/
@Override
final public long writeCheckpoint() {
// write checkpoint and return address of that checkpoint record.
return writeCheckpoint2().getCheckpointAddr();
}
/**
* {@inheritDoc}
*
* @see #load(IRawStore, long)
*/
@Override
final public Checkpoint writeCheckpoint2() {
assertNotTransient();
assertNotReadOnly();
/*
* Note: Acquiring this lock provides for atomicity of the checkpoint of
* the BTree during the commit protocol. Without this lock, users of the
* UnisolatedReadWriteIndex could be concurrently modifying the BTree
* while we are attempting to snapshot it for the commit.
*
* Note: An alternative design would declare a global read/write lock
* for mutation of the indices in addition to the per-BTree read/write
* lock provided by UnisolatedReadWriteIndex. Rather than taking the
* per-BTree write lock here, we would take the global write lock in the
* AbstractJournal's commit protocol, e.g., commitNow(). The global read
* lock would be taken by UnisolatedReadWriteIndex before taking the
* per-BTree write lock. This is effectively a hierarchical locking
* scheme and could provide a workaround if deadlocks are found to occur
* due to lock ordering problems with the acquisition of the
* UnisolatedReadWriteIndex lock (the absence of lock ordering problems
* really hinges around UnisolatedReadWriteLocks not being taken for
* more than one index at a time.)
*
* @see https://sourceforge.net/apps/trac/bigdata/ticket/278
* @see https://sourceforge.net/apps/trac/bigdata/ticket/284
* @see https://sourceforge.net/apps/trac/bigdata/ticket/288
* @see https://sourceforge.net/apps/trac/bigdata/ticket/343
* @see https://sourceforge.net/apps/trac/bigdata/ticket/440
*/
final Lock lock = writeLock();
lock.lock();
try {
/**
* Do not permit checkpoint if the index is in an error state.
*
* @see Invalidate
* BTree objects if error occurs during eviction
*/
if (error != null)
throw new IllegalStateException(ERROR_ERROR_STATE, error);
if (/* autoCommit && */needsCheckpoint()) {
/*
* Flush the btree, write a checkpoint record, and return the
* address of that checkpoint record. The [checkpoint] reference
* is also updated.
*/
return _writeCheckpoint2();
}
/*
* There have not been any writes on this btree or auto-commit is
* disabled.
*
* Note: if the application has explicitly invoked writeCheckpoint()
* then the returned address will be the address of that checkpoint
* record and the BTree will have a new checkpoint address made
* restart safe on the backing store.
*/
return checkpoint;
} finally {
lock.unlock();
}
}
/**
* Core implementation invoked by {@link #writeCheckpoint2()} while holding
* the lock - DO NOT INVOKE THIS METHOD DIRECTLY.
*
* @return the checkpoint.
*/
final private Checkpoint _writeCheckpoint2() {
assertNotTransient();
assertNotReadOnly();
// assert root != null : "root is null"; // i.e., isOpen().
// flush any dirty nodes.
flush();
// pre-condition: all nodes in the tree are clean.
assert root == null || !root.isDirty();
// { // TODO support bloom filter?
// /*
// * Note: Use the [AbstractBtree#bloomFilter] reference here!!!
// *
// * If that reference is [null] then the bloom filter is either
// * clean, disabled, or was not configured. For any of those (3)
// * conditions we will use the address of the bloom filter from the
// * last checkpoint record. If the bloom filter is clean, then we
// * will just carry forward its old address. Otherwise the address in
// * the last checkpoint record will be 0L and that will be carried
// * forward.
// */
// final BloomFilter filter = this.bloomFilter;
//
// if (filter != null && filter.isDirty() && filter.isEnabled()) {
//
// /*
// * The bloom filter is enabled, is loaded and is dirty, so write
// * it on the store now.
// */
//
// filter.write(store);
//
// }
//
// }
if (metadata.getMetadataAddr() == 0L) {
/*
* Is there an old metadata addr in need of recyling?
*/
if (checkpoint != null) {
final long addr = checkpoint.getMetadataAddr();
if (addr != IRawStore.NULL)
store.delete(addr);
}
/*
* The index metadata has been modified so we write out a new
* metadata record on the store.
*/
metadata.write(store);
}
if (checkpoint != null && getRoot() != null
&& checkpoint.getRootAddr() != getRoot().getIdentity()) {
recycle(checkpoint.getRootAddr());
}
if (checkpoint != null) {
recycle(checkpoint.getCheckpointAddr());
}
// create new checkpoint record.
checkpoint = newCheckpoint();
// write it on the store.
checkpoint.write(store);
if (BigdataStatics.debug||INFO) {
final String msg = "name=" + metadata.getName()
+ ", writeQueue{size=" + writeRetentionQueue.size()
+ ",distinct=" + ndistinctOnWriteRetentionQueue + "} : "
+ checkpoint;
if (BigdataStatics.debug)
System.err.println(msg);
if (INFO)
log.info(msg);
}
// return the checkpoint record.
return checkpoint;
}
/**
* Create a {@link Checkpoint} for a {@link HTree}.
*
* The caller is responsible for writing the {@link Checkpoint} record onto
* the store.
*
* The class identified by {@link IndexMetadata#getCheckpointClassName()}
* MUST declare a public constructor with the following method signature
*
*
* ...( HTree htree )
*
*
* @return The {@link Checkpoint}.
*/
@SuppressWarnings("unchecked")
final private Checkpoint newCheckpoint() {
try {
@SuppressWarnings("rawtypes")
final Class cl = Class.forName(metadata.getCheckpointClassName());
/*
* Note: A NoSuchMethodException thrown here means that you did not
* declare the required public constructor on the Checkpoint class
* [cl].
*/
@SuppressWarnings("rawtypes")
final Constructor ctor = cl.getConstructor(new Class[] {
HTree.class //
});
final Checkpoint checkpoint = (Checkpoint) ctor
.newInstance(new Object[] { //
this //
});
return checkpoint;
} catch(Exception ex) {
throw new RuntimeException(ex);
}
}
/*
* CRUD API.
*
* TODO The hash tree intrinsically supports duplicate keys. This means that
* some method semantics must be different. E.g., insert() does not update
* an existing tuple for the same key. remove() removes an arbitrary tuple
* matching the key, lookup() will return an arbitrary match or null if
* there is no match, etc. Also, what corresponds to a lookup scenario in a
* BTree will normally be a bag traversal in an HTree requiring an iterator
* construct.
*
* TODO The hash tree will normally be used with int32 keys, and those keys
* will typically be obtained from Object#hashCode(). Special methods should
* be provided for this purpose. E.g., ISimpleHTree. Custom serialization
* and even a custom mutable leaf data record should be used with this case.
*
* TODO insert() return for htree is never old value since always adds() a
* new tuple never replaces() an existing tuple. Further, if the key and
* val are equals() then we might even define the semantics as a NOP rather
* than appending a duplicate item into the bucket (it's worth thinking on
* this further as scanning for equals is more work and sometimes we might
* want to allow fully duplicated items into the bucket.).
*/
/**
* Convert an int32 hash code key into an unsigned byte[4].
*
* Note: This encoding MUST be consistent with
* {@link IKeyBuilder#append(int)}.
*/
private byte[] i2k(final int key) {
// lexiographic ordering as unsigned int.
int v = key;
if (v < 0) {
v = v - 0x80000000;
} else {
v = 0x80000000 + v;
}
final byte[] buf = new byte[4];
buf[0] = (byte) (v >>> 24);
buf[1] = (byte) (v >>> 16);
buf[2] = (byte) (v >>> 8);
buf[3] = (byte) (v >>> 0);
return buf;
}
// TODO contains with an Object clear needs to test for the Object, not just
// the key. Maybe do this as a wrapper similar to BigdataMap?
public boolean contains(final Object obj) {
//contains(obj.hashCode());
throw new UnsupportedOperationException();
}
public boolean contains(final int key) {
return contains(i2k(key));
}
/**
* Return true iff there is at least one tuple in the hash tree
* having the specified key.
*
* @param key
* The key.
* @return true iff the hash tree contains at least one tuple
* with that key.
* @throws IllegalArgumentException
* if the key is null.
*
* TODO Parallel to insert(), consider a contains() signature
* which permits testing for a specific value as well. Maybe
* in a wrapper class?
*/
public boolean contains(final byte[] key) {
if (key == null)
throw new IllegalArgumentException();
DirectoryPage current = getRoot(); // start at the root.
int prefixLength = 0;// prefix length of the root is always zero.
int buddyOffset = 0; // buddyOffset of the root is always zero.
while (true) {
// skip prefixLength bits and then extract globalDepth bits.
final int hashBits = current.getLocalHashCode(key, prefixLength);
// find the child directory page or bucket page but do not lazily
// create new Directory if not present
final AbstractPage child = current.getChildIfPresent(hashBits);
if (child == null)
return false;
if (child.isLeaf()) {
/*
* Found the bucket page, update it.
*/
final BucketPage bucketPage = (BucketPage) child;
if(!bucketPage.contains(key, buddyOffset)) {
return false;
}
return true;
}
/*
* Recursive descent into a child directory page. We have to update
* the prefixLength and compute the offset of the buddy hash table
* within the child before descending into the child.
*/
prefixLength = prefixLength + current.globalDepth;
buddyOffset = HTreeUtil
.getBuddyOffset(hashBits, current.globalDepth,
child.globalDepth/* localDepthOfChild */);
current = (DirectoryPage) child;
}
}
// public void lookup(final Object obj) {
// lookup(obj.hashCode());
// }
/**
* Return the first value for the key.
*
* @param key
* The key.
*
* @return The first value for the key -or- null if there are
* no tuples in the index having that key. Note that the return
* value is not diagnostic if the application allows
* null values into the index.
*/
public byte[] lookupFirst(final int key) {
return lookupFirst(i2k(key));
}
/**
* Return the first value for the key.
*
* @param key
* The key.
*
* @return The first value for the key -or- null if there are
* no tuples in the index having that key. Note that the return
* value is not diagnostic if the application allows
* null values into the index.
*/
public byte[] lookupFirst(final byte[] key) {
if (key == null)
throw new IllegalArgumentException();
DirectoryPage current = getRoot(); // start at the root.
int prefixLength = 0;// prefix length of the root is always zero.
int buddyOffset = 0; // buddyOffset of the root is always zero.
while (true) {
// skip prefixLength bits and then extract globalDepth bits.
final int hashBits = current.getLocalHashCode(key, prefixLength);
// find the child directory page or bucket page and ensure a new
// child is not created on lookup
final AbstractPage child = current.getChildIfPresent(hashBits);
if (child == null)
return null;
if (child.isLeaf()) {
/*
* Found the bucket page, search it for a match.
*/
final BucketPage bucketPage = (BucketPage) child;
return bucketPage.lookupFirst(key, buddyOffset);
}
/*
* Recursive descent into a child directory page. We have to update
* the prefixLength and compute the offset of the buddy hash table
* within the child before descending into the child.
*/
prefixLength = prefixLength + current.globalDepth;
buddyOffset = HTreeUtil
.getBuddyOffset(hashBits, current.globalDepth,
child.globalDepth/* localDepthOfChild */);
current = (DirectoryPage) child;
}
}
/**
* Return an iterator which will visit each tuple in the index having the
* specified key.
*
* @param key
* The key.
*
* @return The iterator and never null.
*/
public ITupleIterator lookupAll(final int key) {
return lookupAll(i2k(key));
}
/**
* Return an iterator which will visit each tuple in the index having the
* specified key.
*
* @param key
* The key.
*
* @return The iterator and never null.
*/
public ITupleIterator lookupAll(final byte[] key) {
if (key == null)
throw new IllegalArgumentException();
DirectoryPage current = getRoot(); // start at the root.
int prefixLength = 0;// prefix length of the root is always zero.
int buddyOffset = 0; // buddyOffset of the root is always zero.
while (true) {
// skip prefixLength bits and then extract globalDepth bits.
final int hashBits = current.getLocalHashCode(key, prefixLength);
// find the child directory page or bucket page.
// Ensure we do not create a child for lookup
final AbstractPage child = current.getChildIfPresent(hashBits);
if (child == null)
return emptyTupleIterator();
if (child.isLeaf()) {
/*
* Found the bucket page, search it for a match.
*/
final BucketPage bucketPage = (BucketPage) child;
return bucketPage.lookupAll(key);//, buddyOffset);
} else if (((DirectoryPage)child).isOverflowDirectory()) {
return ((DirectoryPage) child).getTuples();
}
/*
* Recursive descent into a child directory page. We have to update
* the prefixLength and compute the offset of the buddy hash table
* within the child before descending into the child.
*/
prefixLength = prefixLength + current.globalDepth;
buddyOffset = HTreeUtil
.getBuddyOffset(hashBits, current.globalDepth,
child.globalDepth/* localDepthOfChild */);
current = (DirectoryPage) child;
}
}
private ITupleIterator emptyTupleIterator() {
return new ITupleIterator() {
public ITuple next() {
throw new NoSuchElementException();
}
public boolean hasNext() {
return false;
}
public void remove() {
throw new UnsupportedOperationException();
}
};
}
public void insert(final Object obj) {
insert(obj.hashCode(), SerializerUtil.serialize(obj));
}
public void insert(final int key, final byte[] val) {
insert(i2k(key), val);
}
/**
* Insert a tuple into the hash tree. Tuples with duplicate keys and even
* tuples with duplicate keys and values are allowed and will result in
* multiple tuples.
*
* @param key
* The key.
* @param value
* The value.
* @return null (always).
*
* TODO If the application wants to restrict the hash tree to such
* that it does not contain duplicate tuples then it must first
* search in the tree for an exact match (key and value). It is
* easier to do that from within the insert logic so expand the
* method signature to pass an insert enum {ALLDUPS,DUPKEYS,NODUPS}.
*/
public byte[] insert(final byte[] key, final byte[] value) {
if (DEBUG)
log.debug("key=" + BytesUtil.toString(key) + ", value="
+ Arrays.toString(value));
if (key == null)
throw new IllegalArgumentException();
// the current directory page.
DirectoryPage current = getRoot(); // start at the root.
// #of prefix bits already consumed.
int prefixLength = 0;// prefix length of the root is always zero.
// buddyOffset into [current].
int buddyOffset = 0; // buddyOffset of the root is always zero.
while (true) {
// skip prefixLength bits and then extract globalDepth bits.
assert !(prefixLength >= key.length * 8 && !current.isOverflowDirectory());
final int hashBits = current.getLocalHashCode(key, prefixLength);
// find the child directory page or bucket page.
final AbstractPage child;
if (current.isOverflowDirectory()) {
if (!BytesUtil.bytesEqual(key, current.getOverflowKey())) {
// if not the overflowKey, then insert extra level
final DirectoryPage pd = current.getParentDirectory();
assert !pd.isOverflowDirectory();
assert pd.isReadOnly() ? current.isReadOnly() : true;
current = pd._addLevelForOverflow(current);
// we need to fix this since we have introduced a new level
// between the old current and its parent directory
child = current;
// and frig prefixlength to come back in
prefixLength -= current.globalDepth;
// if (DEBUG)
// log.debug("frig prefixLength: " + prefixLength);
} else {
child = current.lastChild();
}
} else {
child = current.getChild(hashBits, buddyOffset);
}
if (child.isLeaf()) {
/*
* Found the bucket page, update it.
*
* We must copyOnWrite now since the insert will otherwise call it
* and potentially invalidate the bucketPage reference.
*/
final BucketPage bucketPage = (BucketPage) child.copyOnWrite();
// Attempt to insert the tuple into the bucket.
if (!bucketPage.insert(key, value)) {
if (current.globalDepth == child.globalDepth) {
/*
* The child is at the same depth as the parent. Either
* we can split a directory page which is a parent of
* that bucket or we have to add a new level below the
* root on the path to that bucket.
*/
if (child.globalDepth == addressBits) {
bucketPage.addLevel();
} else {
current.getParentDirectory().split(buddyOffset, current/* oldChild */);
}
} else {
// globalDepth >= localDepth
bucketPage.split();
}
return insert(key,value);
}
return null; // TODO should be Void return? or depends on enum controlling dups behavior?
}
/*
* Recursive descent into a child directory page. We have to update
* the prefixLength and compute the offset of the buddy hash table
* within the child before descending into the child.
*/
// increase prefix length by the #of address bits consumed by the
// buddy hash table in the current directory page as we descend.
prefixLength = prefixLength + current.globalDepth;
// find the offset of the buddy hash table in the child.
buddyOffset = HTreeUtil
.getBuddyOffset(hashBits, current.globalDepth,
child.globalDepth/* localDepthOfChild */);
// update current so we can search in the child.
current = (DirectoryPage) child;
}
} // insert()
/**
* Insert a tuple into the hash tree. Tuples with duplicate keys and even
* tuples with duplicate keys and values are allowed and will result in
* multiple tuples.
*
* @param src
* The source {@link BucketPage} src
* @param slot
* The slot in the source {@link BucketPage} whose tuple will be
* inserted (really copied).
*/
protected void insertRawTuple(final BucketPage src, final int slot) {
if (src == null)
throw new IllegalArgumentException();
if (slot < 0 || slot >= (1 << addressBits)) // [0:slotsPerPage].
throw new IllegalArgumentException();
// the key to insert
final byte[] key = src.getKeys().get(slot);
if (key == null)
throw new IllegalArgumentException();
if (DEBUG)
log.debug("key=" + BytesUtil.toString(key));
// the current directory page.
DirectoryPage current = getRoot(); // start at the root.
// #of prefix bits already consumed.
int prefixLength = 0;// prefix length of the root is always zero.
// buddyOffset into [current].
int buddyOffset = 0; // buddyOffset of the root is always zero.
while (true) {
// skip prefixLength bits and then extract globalDepth bits.
final int hashBits = current.getLocalHashCode(key, prefixLength);
// find the child directory page or bucket page.
final AbstractPage child = current.getChild(hashBits, buddyOffset);
if (child.isLeaf()) {
/*
* Found the bucket page, update it.
*
* Must ensure we have copyOnWriteVersion since otherwise the bucketPage
* later referenced will not be valid
*/
final BucketPage bucketPage = (BucketPage) child.copyOnWrite();
// Attempt to insert the tuple into the bucket.
if (!bucketPage.insertRawTuple(src, slot, key)) {
if (current.globalDepth == child.globalDepth) {
/*
* The child is at the same depth as the parent. Either
* we can split a directory page which is a parent of
* that bucket or we have to add a new level below the
* root on the path to that bucket.
*/
if (child.globalDepth == addressBits) {
// addLevel2(bucketPage);
bucketPage.addLevel();
} else {
current.getParentDirectory().split(
buddyOffset, current/* oldChild */);
}
} else {
// globalDepth >= localDepth
bucketPage.split();
}
insertRawTuple(src, slot);
return;
}
return;
}
/*
* Recursive descent into a child directory page. We have to update
* the prefixLength and compute the offset of the buddy hash table
* within the child before descending into the child.
*/
// increase prefix length by the #of address bits consumed by the
// buddy hash table in the current directory page as we descend.
prefixLength = prefixLength + current.globalDepth;
// find the offset of the buddy hash table in the child.
buddyOffset = HTreeUtil
.getBuddyOffset(hashBits, current.globalDepth,
child.globalDepth/* localDepthOfChild */);
// update current so we can search in the child.
current = (DirectoryPage) child;
}
} // insertRawTuple()
/**
* Removes a single entry matching the key supplied.
* The HTree provides no guarantee that the order in which a value
* with a duplicate key is added will be the order in which it
* would be removed - FIFO. It is more likely to be in LIFO
*
* @param key
* @return the value removed or null if none found
*/
public byte[] remove(final byte[] key) {
if (key == null)
throw new IllegalArgumentException();
final AbstractPage page = locatePageForKey(key);
final byte[] ret = page == null ? null : page.removeFirst(key);
if (ret != null) nentries--;
return ret;
}
public int removeAll(final byte[] key) {
if (key == null)
throw new IllegalArgumentException();
final AbstractPage page = locatePageForKey(key);
final int removals = page == null ? 0 : page.removeAll(key);
nentries -= removals;
return removals;
}
/**
*
*/
protected AbstractPage locatePageForKey(final byte[] key) {
if (key == null)
throw new IllegalArgumentException();
DirectoryPage current = getRoot(); // start at the root.
int prefixLength = 0;// prefix length of the root is always zero.
while (true) {
// skip prefixLength bits and then extract globalDepth bits.
final int hashBits = current.getLocalHashCode(key, prefixLength);
// find the child directory page or bucket page, ensuring that
// new Directory is not created if not present
final AbstractPage child = current.getChildIfPresent(hashBits);
if (child == null || child.isLeaf() || ((DirectoryPage) child).isOverflowDirectory()) {
return child;
}
/*
* Recursive descent into a child directory page. We have to update
* the prefixLength before descending into the child.
*/
prefixLength = prefixLength + current.globalDepth;
current = (DirectoryPage) child;
}
}
public void removeAll() {
DirectoryPage root = getRoot();
root.removeAll();
newRoot();
}
public long rangeCount() {
return nentries;
}
/**
* Pretty print the {@link HTree}.
*/
String PP() {
return PP(true);
}
String PP(final boolean showBinary) {
final StringBuilder sb = new StringBuilder();
sb.append("#nodes=" + nnodes + ", #leaves=" + nleaves + ", #entries="
+ nentries + "\n");
root.PP(sb, showBinary);
return sb.toString();
}
@Override
public BaseIndexStats dumpPages(final boolean recursive, final boolean visitLeaves) {
if (!recursive) {
return new BaseIndexStats(this);
}
final HTreePageStats stats = new HTreePageStats();
getRoot().dumpPages(recursive, visitLeaves, stats);
return stats;
}
/**
* Create a new {@link HTree} or derived class. This method works by writing
* the {@link IndexMetadata} record on the store and then loading the
* {@link HTree} from the {@link IndexMetadata} record.
*
* @param store
* The store.
*
* @param metadata
* The metadata record.
*
* @return The newly created {@link HTree}.
*
* @see #load(IRawStore, long, boolean)
*
* @throws IllegalStateException
* If you attempt to create two {@link HTree} objects from the
* same metadata record since the metadata address will have
* already been noted on the {@link IndexMetadata} object. You
* can use {@link IndexMetadata#clone()} to obtain a new copy of
* the metadata object with the metadata address set to
* 0L.
* @exception IllegalStateException
* if the {@link IndexTypeEnum} in the supplied
* {@link IndexMetadata} object is not
* {@link IndexTypeEnum#BTree}.
*/
public static HTree create(final IRawStore store,
final HTreeIndexMetadata metadata) {
if (metadata.getIndexType() != IndexTypeEnum.HTree) {
throw new IllegalStateException("Wrong index type: "
+ metadata.getIndexType());
}
if (store == null) {
// Create an htree which is NOT backed by a persistence store.
return createTransient(metadata);
}
if (metadata.getMetadataAddr() != 0L) {
throw new IllegalStateException("Metadata record already in use");
}
/*
* Write metadata record on store. The address of that record is set as
* a side-effect on the metadata object.
*/
metadata.write(store);
/*
* Create checkpoint for the new H+Tree.
*/
final Checkpoint firstCheckpoint = metadata.firstCheckpoint();
/*
* Write the checkpoint record on the store. The address of the
* checkpoint record is set on the object as a side effect.
*/
firstCheckpoint.write(store);
/*
* Load the HTree from the store using that checkpoint record. There is
* no root so a new root leaf will be created when the HTree is opened.
*/
return load(store, firstCheckpoint.getCheckpointAddr(), false/* readOnly */);
}
/**
* Create a new {@link HTree} or derived class that is fully transient (NO
* backing {@link IRawStore}).
*
* Fully transient {@link HTree}s provide the functionality of a {@link HTree}
* without a backing persistence store. Internally, reachable nodes and
* leaves of the transient {@link HTree} use hard references to ensure that
* remain strongly reachable. Deleted nodes and leaves simply clear their
* references and will be swept by the garbage collector shortly thereafter.
*
* Operations which attempt to write on the backing store will fail.
*
* While nodes and leaves are never persisted, the keys and values of the
* transient {@link HTree} are unsigned byte[]s. This means that application
* keys and values are always converted into unsigned byte[]s before being
* stored in the {@link HTree}. Hence if an object that is inserted into
* the {@link HTree} and then looked up using the {@link HTree} API, you
* WILL NOT get back the same object reference.
*
* Note: CLOSING A TRANSIENT INDEX WILL DISCARD ALL DATA!
*
* @param metadata
* The metadata record.
*
* @return The transient {@link HTree}.
*/
@SuppressWarnings("unchecked")
public static HTree createTransient(final HTreeIndexMetadata metadata) {
if (metadata.getIndexType() != IndexTypeEnum.HTree) {
throw new IllegalStateException("Wrong index type: "
+ metadata.getIndexType());
}
/*
* Create checkpoint for the new HTree.
*/
final Checkpoint firstCheckpoint = metadata.firstCheckpoint();
/*
* Create B+Tree object instance.
*/
try {
final Class cl = Class.forName(metadata.getHTreeClassName());
/*
* Note: A NoSuchMethodException thrown here means that you did not
* declare the required public constructor for a class derived from
* BTree.
*/
final Constructor ctor = cl.getConstructor(new Class[] {
IRawStore.class,//
Checkpoint.class,//
IndexMetadata.class,//
Boolean.TYPE//
});
final HTree htree = (HTree) ctor.newInstance(new Object[] { //
null , // store
firstCheckpoint, //
metadata, //
false// readOnly
});
// create the root node.
htree.reopen();
return htree;
} catch (Exception ex) {
throw new RuntimeException(ex);
}
}
/**
* Load an instance of a {@link HTree} or derived class from the store. The
* {@link HTree} or derived class MUST declare a constructor with the
* following signature:
*
* className(IRawStore store, Checkpoint checkpoint, IndexMetadata metadata, boolean readOnly)
*
*
*
* @param store
* The store.
* @param addrCheckpoint
* The address of a {@link Checkpoint} record for the index.
* @param readOnly
* When true the {@link BTree} will be marked as
* read-only. Marking has some advantages relating to the locking
* scheme used by {@link Node#getChild(int)} since the root node
* is known to be read-only at the time that it is allocated as
* per-child locking is therefore in place for all nodes in the
* read-only {@link BTree}. It also results in much higher
* concurrency for {@link AbstractBTree#touch(AbstractNode)}.
*
* @return The {@link HTree} or derived class loaded from that
* {@link Checkpoint} record.
*
* @throws IllegalArgumentException
* if store is null.
*/
@SuppressWarnings("unchecked")
public static HTree load(final IRawStore store, final long addrCheckpoint,
final boolean readOnly) {
if (store == null)
throw new IllegalArgumentException();
/*
* Read checkpoint record from store.
*/
final Checkpoint checkpoint;
try {
checkpoint = Checkpoint.load(store, addrCheckpoint);
} catch (Throwable t) {
throw new RuntimeException("Could not load Checkpoint: store="
+ store + ", addrCheckpoint="
+ store.toString(addrCheckpoint), t);
}
if (checkpoint.getIndexType() != IndexTypeEnum.HTree)
throw new RuntimeException("Not an HTree checkpoint: " + checkpoint);
/*
* Read metadata record from store.
*/
final HTreeIndexMetadata metadata;
try {
metadata = (HTreeIndexMetadata) IndexMetadata.read(store,
checkpoint.getMetadataAddr());
} catch (Throwable t) {
throw new RuntimeException("Could not read IndexMetadata: store="
+ store + ", checkpoint=" + checkpoint, t);
}
if (INFO) {
// Note: this is the scale-out index name for a partitioned index.
final String name = metadata.getName();
log.info((name == null ? "" : "name=" + name + ", ")
+ "readCheckpoint=" + checkpoint);
}
/*
* Create HTree object instance.
*/
try {
final Class cl = Class.forName(metadata.getHTreeClassName());
/*
* Note: A NoSuchMethodException thrown here means that you did not
* declare the required public constructor for a class derived from
* BTree.
*/
final Constructor ctor = cl.getConstructor(new Class[] {
IRawStore.class,//
Checkpoint.class,//
IndexMetadata.class, //
Boolean.TYPE
});
final HTree htree = (HTree) ctor.newInstance(new Object[] { //
store,//
checkpoint, //
metadata, //
readOnly
});
// if (readOnly) {
//
// btree.setReadOnly(true);
//
// }
// read the root node.
htree.reopen();
return htree;
} catch (Exception ex) {
throw new RuntimeException(ex);
}
}
/**
* Recycle (aka delete) the allocation. This method also adjusts the #of
* bytes released in the {@link BTreeCounters}.
*
* @param addr
* The address to be recycled.
*
* @return The #of bytes which were recycled and ZERO (0) if the address is
* {@link IRawStore#NULL}.
*/
protected int recycle(final long addr) {
if (addr == IRawStore.NULL)
return 0;
final int nbytes = store.getByteCount(addr);
// getBtreeCounters().bytesReleased += nbytes;
store.delete(addr);
return nbytes;
}
}