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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.cassandra.cql3;
import java.nio.ByteBuffer;
import java.util.List;
import java.util.Locale;
import java.util.concurrent.ConcurrentMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import com.google.common.collect.MapMaker;
import org.apache.cassandra.cache.IMeasurableMemory;
import org.apache.cassandra.config.CFMetaData;
import org.apache.cassandra.config.ColumnDefinition;
import org.apache.cassandra.cql3.selection.Selectable;
import org.apache.cassandra.cql3.selection.Selector;
import org.apache.cassandra.cql3.selection.SimpleSelector;
import org.apache.cassandra.db.marshal.AbstractType;
import org.apache.cassandra.exceptions.InvalidRequestException;
import org.apache.cassandra.db.marshal.UTF8Type;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.ObjectSizes;
import org.apache.cassandra.utils.memory.AbstractAllocator;
/**
* Represents an identifer for a CQL column definition.
* TODO : should support light-weight mode without text representation for when not interned
*/
public class ColumnIdentifier extends Selectable implements IMeasurableMemory, Comparable
{
private static final Pattern PATTERN_DOUBLE_QUOTE = Pattern.compile("\"", Pattern.LITERAL);
public final ByteBuffer bytes;
private final String text;
/**
* since these objects are compared frequently, we stash an efficiently compared prefix of the bytes, in the expectation
* that the majority of comparisons can be answered by this value only
*/
public final long prefixComparison;
private final boolean interned;
private static final Pattern UNQUOTED_IDENTIFIER = Pattern.compile("[a-z][a-z0-9_]*");
private static final long EMPTY_SIZE = ObjectSizes.measure(new ColumnIdentifier(ByteBufferUtil.EMPTY_BYTE_BUFFER, "", false));
private static final ConcurrentMap internedInstances = new MapMaker().weakValues().makeMap();
private static final class InternedKey
{
private final AbstractType type;
private final ByteBuffer bytes;
InternedKey(AbstractType type, ByteBuffer bytes)
{
this.type = type;
this.bytes = bytes;
}
@Override
public boolean equals(Object o)
{
if (this == o)
return true;
if (o == null || getClass() != o.getClass())
return false;
InternedKey that = (InternedKey) o;
return bytes.equals(that.bytes) && type.equals(that.type);
}
@Override
public int hashCode()
{
return bytes.hashCode() + 31 * type.hashCode();
}
}
private static long prefixComparison(ByteBuffer bytes)
{
long prefix = 0;
ByteBuffer read = bytes.duplicate();
int i = 0;
while (read.hasRemaining() && i < 8)
{
prefix <<= 8;
prefix |= read.get() & 0xFF;
i++;
}
prefix <<= (8 - i) * 8;
// by flipping the top bit (==Integer.MIN_VALUE), we ensure that signed comparison gives the same result
// as an unsigned without the bit flipped
prefix ^= Long.MIN_VALUE;
return prefix;
}
public ColumnIdentifier(String rawText, boolean keepCase)
{
this.text = keepCase ? rawText : rawText.toLowerCase(Locale.US);
this.bytes = ByteBufferUtil.bytes(this.text);
this.prefixComparison = prefixComparison(bytes);
this.interned = false;
}
public ColumnIdentifier(ByteBuffer bytes, AbstractType type)
{
this(bytes, type.getString(bytes), false);
}
public ColumnIdentifier(ByteBuffer bytes, String text)
{
this(bytes, text, false);
}
private ColumnIdentifier(ByteBuffer bytes, String text, boolean interned)
{
this.bytes = bytes;
this.text = text;
this.interned = interned;
this.prefixComparison = prefixComparison(bytes);
}
public static ColumnIdentifier getInterned(ByteBuffer bytes, AbstractType type)
{
return getInterned(type, bytes, type.getString(bytes));
}
public static ColumnIdentifier getInterned(String rawText, boolean keepCase)
{
String text = keepCase ? rawText : rawText.toLowerCase(Locale.US);
ByteBuffer bytes = ByteBufferUtil.bytes(text);
return getInterned(UTF8Type.instance, bytes, text);
}
public static ColumnIdentifier getInterned(AbstractType type, ByteBuffer bytes, String text)
{
bytes = ByteBufferUtil.minimalBufferFor(bytes);
InternedKey key = new InternedKey(type, bytes);
ColumnIdentifier id = internedInstances.get(key);
if (id != null)
return id;
ColumnIdentifier created = new ColumnIdentifier(bytes, text, true);
ColumnIdentifier previous = internedInstances.putIfAbsent(key, created);
return previous == null ? created : previous;
}
public boolean isInterned()
{
return interned;
}
@Override
public final int hashCode()
{
return bytes.hashCode();
}
@Override
public final boolean equals(Object o)
{
if (this == o)
return true;
if(!(o instanceof ColumnIdentifier))
return false;
ColumnIdentifier that = (ColumnIdentifier)o;
return bytes.equals(that.bytes);
}
@Override
public String toString()
{
return text;
}
/**
* Returns a string representation of the identifier that is safe to use directly in CQL queries.
* In necessary, the string will be double-quoted, and any quotes inside the string will be escaped.
*/
public String toCQLString()
{
return maybeQuote(text);
}
public long unsharedHeapSize()
{
return EMPTY_SIZE
+ ObjectSizes.sizeOnHeapOf(bytes)
+ ObjectSizes.sizeOf(text);
}
public long unsharedHeapSizeExcludingData()
{
return EMPTY_SIZE
+ ObjectSizes.sizeOnHeapExcludingData(bytes)
+ ObjectSizes.sizeOf(text);
}
public ColumnIdentifier clone(AbstractAllocator allocator)
{
return interned ? this : new ColumnIdentifier(allocator.clone(bytes), text, false);
}
public Selector.Factory newSelectorFactory(CFMetaData cfm, List defs) throws InvalidRequestException
{
ColumnDefinition def = cfm.getColumnDefinitionForCQL(this);
if (def == null)
throw new InvalidRequestException(String.format("Undefined name %s in selection clause", this));
return SimpleSelector.newFactory(def, addAndGetIndex(def, defs));
}
public int compareTo(ColumnIdentifier that)
{
int c = Long.compare(this.prefixComparison, that.prefixComparison);
if (c != 0)
return c;
if (this == that)
return 0;
return ByteBufferUtil.compareUnsigned(this.bytes, that.bytes);
}
/**
* Because Thrift-created tables may have a non-text comparator, we cannot determine the proper 'key' until
* we know the comparator. ColumnIdentifier.Raw is a placeholder that can be converted to a real ColumnIdentifier
* once the comparator is known with prepare(). This should only be used with identifiers that are actual
* column names. See CASSANDRA-8178 for more background.
*/
public static interface Raw extends Selectable.Raw
{
public ColumnIdentifier prepare(CFMetaData cfm);
/**
* Returns a string representation of the identifier that is safe to use directly in CQL queries.
* In necessary, the string will be double-quoted, and any quotes inside the string will be escaped.
*/
public String toCQLString();
}
public static class Literal implements Raw
{
private final String rawText;
private final String text;
public Literal(String rawText, boolean keepCase)
{
this.rawText = rawText;
this.text = keepCase ? rawText : rawText.toLowerCase(Locale.US);
}
public ColumnIdentifier prepare(CFMetaData cfm)
{
if (!cfm.isStaticCompactTable())
return getInterned(text, true);
AbstractType thriftColumnNameType = cfm.thriftColumnNameType();
if (thriftColumnNameType instanceof UTF8Type)
return getInterned(text, true);
// We have a Thrift-created table with a non-text comparator. Check if we have a match column, otherwise assume we should use
// thriftColumnNameType
ByteBuffer bufferName = ByteBufferUtil.bytes(text);
for (ColumnDefinition def : cfm.allColumns())
{
if (def.name.bytes.equals(bufferName))
return def.name;
}
return getInterned(thriftColumnNameType, thriftColumnNameType.fromString(rawText), text);
}
public boolean processesSelection()
{
return false;
}
@Override
public final int hashCode()
{
return text.hashCode();
}
@Override
public final boolean equals(Object o)
{
if(!(o instanceof Literal))
return false;
Literal that = (Literal) o;
return text.equals(that.text);
}
@Override
public String toString()
{
return text;
}
public String toCQLString()
{
return maybeQuote(text);
}
}
public static class ColumnIdentifierValue implements Raw
{
private final ColumnIdentifier identifier;
public ColumnIdentifierValue(ColumnIdentifier identifier)
{
this.identifier = identifier;
}
public ColumnIdentifier prepare(CFMetaData cfm)
{
return identifier;
}
public boolean processesSelection()
{
return false;
}
@Override
public final int hashCode()
{
return identifier.hashCode();
}
@Override
public final boolean equals(Object o)
{
if(!(o instanceof ColumnIdentifierValue))
return false;
ColumnIdentifierValue that = (ColumnIdentifierValue) o;
return identifier.equals(that.identifier);
}
@Override
public String toString()
{
return identifier.toString();
}
public String toCQLString()
{
return maybeQuote(identifier.text);
}
}
public static String maybeQuote(String text)
{
if (UNQUOTED_IDENTIFIER.matcher(text).matches() && !ReservedKeywords.isReserved(text))
return text;
return '"' + PATTERN_DOUBLE_QUOTE.matcher(text).replaceAll(Matcher.quoteReplacement("\"\"")) + '"';
}
}
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