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Flexible cache implementation options in CompilingResultSetMapper

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This commit is contained in:
Travis Burtrum 2017-05-17 12:35:28 -04:00
parent 34a7a55bfc
commit 9310c759e6
2 changed files with 119 additions and 4 deletions
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2
beehive-jdbc-mapper/src/main/java/com/moparisthebest/jdbc/CachingRowToObjectMapper.java
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@ -44,7 +44,7 @@ public class CachingRowToObjectMapper<T> extends RowToObjectMapper<T> {
}
}
static class ResultSetKey {
public static class ResultSetKey {
protected final String[] keys;
protected final Class<?> returnTypeClass;

121
beehive-jdbc-mapper/src/main/java/com/moparisthebest/jdbc/CompilingResultSetMapper.java
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@ -5,27 +5,142 @@ import com.moparisthebest.classgen.Compiler;
import java.sql.ResultSet;
import java.util.Calendar;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
* This generally follows the contract of ResultSetMapper, with the differences specified in CompilingRowToObjectMapper.
* <p>
* This does cache compiled code based on column name/order and DTO being mapped to, so the (rather heavy)
* code generation/compilation/instantiation only happens once for each query/dto, and is very fast on subsequent calls.
* <p>
* By default this uses a plain HashMap for the cache, unbounded, and not thread-safe. There are overloaded constructors
* you can use to tell it to be threadSafe in which case it uses an unbounded ConcurrentHashMap, or to give it a maxEntries
* in which case it uses a LinkedHashMap and clears out old entries in LRU order keeping only maxEntries. Lastly you can
* send in your own custom Map implementation, CompilingResultSetMapper guarantees null will never be used for key or value.
*
* @see CompilingRowToObjectMapper
*/
public class CompilingResultSetMapper extends ResultSetMapper {
protected final Compiler compiler = new Compiler();
protected final Map<CachingRowToObjectMapper.ResultSetKey, CompilingRowToObjectMapper.ResultSetToObject<?>> cache = new HashMap<CachingRowToObjectMapper.ResultSetKey, CompilingRowToObjectMapper.ResultSetToObject<?>>();
protected final Map<CachingRowToObjectMapper.ResultSetKey, CompilingRowToObjectMapper.ResultSetToObject<?>> cache;
public CompilingResultSetMapper(Calendar cal, int arrayMaxLength) {
/**
* CompilingResultSetMapper with optional maxEntries, expiring old ones in LRU fashion
*
* @param cal optional calendar for date/time values
* @param arrayMaxLength max array/list/map length, a value of less than 1 indicates that all rows from the ResultSet should be included
* @param maxEntries max cached compiled entries to keep in cache, < 1 means unlimited
*/
public CompilingResultSetMapper(final Calendar cal, final int arrayMaxLength, final int maxEntries) {
super(cal, arrayMaxLength);
if (maxEntries > 0) { // we want a limited cache
final float loadFactor = 0.75f; // default for HashMaps
// if we set the initialCapacity this way, nothing should ever need re-sized
final int initialCapacity = ((int) Math.ceil(maxEntries / loadFactor)) + 1;
cache = new LinkedHashMap<CachingRowToObjectMapper.ResultSetKey, CompilingRowToObjectMapper.ResultSetToObject<?>>(initialCapacity, loadFactor, true) {
@Override
protected boolean removeEldestEntry(final Map.Entry<CachingRowToObjectMapper.ResultSetKey, CompilingRowToObjectMapper.ResultSetToObject<?>> eldest) {
return size() > maxEntries;
}
};
} else
cache = new HashMap<CachingRowToObjectMapper.ResultSetKey, CompilingRowToObjectMapper.ResultSetToObject<?>>();
}
/**
* CompilingResultSetMapper with unlimited cache
*
* @param cal optional calendar for date/time values
* @param arrayMaxLength max array/list/map length, a value of less than 1 indicates that all rows from the ResultSet should be included
*/
public CompilingResultSetMapper(final Calendar cal, final int arrayMaxLength) {
this(cal, arrayMaxLength, 0); // default unlimited cache
}
/**
* CompilingResultSetMapper with unlimited cache
*
* @param arrayMaxLength max array/list/map length, a value of less than 1 indicates that all rows from the ResultSet should be included
*/
public CompilingResultSetMapper(final int arrayMaxLength) {
this(null, arrayMaxLength);
}
/**
* CompilingResultSetMapper with unlimited cache
*/
public CompilingResultSetMapper() {
super();
this(-1);
}
/**
* CompilingResultSetMapper with custom cache implementation
*
* @param cal optional calendar for date/time values
* @param arrayMaxLength max array/list/map length, a value of less than 1 indicates that all rows from the ResultSet should be included
* @param cache any Map implementation for cache you wish, does not need to handle null keys or values
*/
public CompilingResultSetMapper(final Calendar cal, final int arrayMaxLength, final Map<CachingRowToObjectMapper.ResultSetKey, CompilingRowToObjectMapper.ResultSetToObject<?>> cache) {
super(cal, arrayMaxLength);
if (cache == null)
throw new IllegalArgumentException("cache cannot be null");
this.cache = cache;
}
/**
* CompilingResultSetMapper with custom cache implementation
*
* @param arrayMaxLength max array/list/map length, a value of less than 1 indicates that all rows from the ResultSet should be included
* @param cache any Map implementation for cache you wish, does not need to handle null keys or values
*/
public CompilingResultSetMapper(final int arrayMaxLength, final Map<CachingRowToObjectMapper.ResultSetKey, CompilingRowToObjectMapper.ResultSetToObject<?>> cache) {
this(null, arrayMaxLength, cache);
}
/**
* CompilingResultSetMapper with custom cache implementation
*
* @param cache any Map implementation for cache you wish, does not need to handle null keys or values
*/
public CompilingResultSetMapper(final Map<CachingRowToObjectMapper.ResultSetKey, CompilingRowToObjectMapper.ResultSetToObject<?>> cache) {
this(-1, cache);
}
/**
* CompilingResultSetMapper with optionally threadSafe cache implementation
*
* @param cal optional calendar for date/time values
* @param arrayMaxLength max array/list/map length, a value of less than 1 indicates that all rows from the ResultSet should be included
* @param threadSafe true uses a thread-safe cache implementation (currently ConcurrentHashMap), false uses regular HashMap
*/
public CompilingResultSetMapper(final Calendar cal, final int arrayMaxLength, final boolean threadSafe) {
this(cal, arrayMaxLength, threadSafe ?
new ConcurrentHashMap<CachingRowToObjectMapper.ResultSetKey, CompilingRowToObjectMapper.ResultSetToObject<?>>()
:
new HashMap<CachingRowToObjectMapper.ResultSetKey, CompilingRowToObjectMapper.ResultSetToObject<?>>()
);
}
/**
* CompilingResultSetMapper with optionally threadSafe cache implementation
*
* @param arrayMaxLength max array/list/map length, a value of less than 1 indicates that all rows from the ResultSet should be included
* @param threadSafe true uses a thread-safe cache implementation (currently ConcurrentHashMap), false uses regular HashMap
*/
public CompilingResultSetMapper(final int arrayMaxLength, final boolean threadSafe) {
this(null, arrayMaxLength, threadSafe);
}
/**
* CompilingResultSetMapper with optionally threadSafe cache implementation
*
* @param threadSafe true uses a thread-safe cache implementation (currently ConcurrentHashMap), false uses regular HashMap
*/
public CompilingResultSetMapper(final boolean threadSafe) {
this(-1, threadSafe);
}
@Override