Make CachingResultSetMapper not have an entire cache shared over the whole application, only per instance, also fix hashing logic

pull/2/head
Travis Burtrum 6 years ago
parent 1b2f248574
commit 9d131e13ce

@ -2,9 +2,13 @@ package com.moparisthebest.jdbc;
import java.sql.ResultSet;
import java.util.Calendar;
import java.util.HashMap;
import java.util.Map;
public class CachingResultSetMapper extends ResultSetMapper {
protected final Map<CachingRowToObjectMapper.ResultSetKey, CachingRowToObjectMapper.FieldMapping> cache = new HashMap<CachingRowToObjectMapper.ResultSetKey, CachingRowToObjectMapper.FieldMapping>();
public CachingResultSetMapper(Calendar cal, int arrayMaxLength) {
super(cal, arrayMaxLength);
}
@ -15,6 +19,6 @@ public class CachingResultSetMapper extends ResultSetMapper {
@Override
protected <T> RowToObjectMapper<T> getRowMapper(ResultSet resultSet, Class<T> returnTypeClass, Calendar cal, Class<?> mapValType) {
return new CachingRowToObjectMapper<T>(resultSet, returnTypeClass, cal, mapValType);
return new CachingRowToObjectMapper<T>(cache, resultSet, returnTypeClass, cal, mapValType);
}
}

@ -5,22 +5,19 @@ import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Arrays;
import java.util.Calendar;
import java.util.HashMap;
import java.util.Map;
public class CachingRowToObjectMapper<T> extends RowToObjectMapper<T> {
protected static final Map<Integer, FieldMapping> cache = new HashMap<Integer, FieldMapping>();
protected final Map<ResultSetKey, FieldMapping> cache;
protected final ResultSetKey keys;
protected final int thisHash;
protected final String[] keys;
public CachingRowToObjectMapper(ResultSet resultSet, Class<T> returnTypeClass, Calendar cal, Class<?> mapValType) {
public CachingRowToObjectMapper(final Map<ResultSetKey, FieldMapping> cache, ResultSet resultSet, Class<T> returnTypeClass, Calendar cal, Class<?> mapValType) {
super(resultSet, returnTypeClass, cal, mapValType);
this.cache = cache;
try {
keys = super.getKeysFromResultSet();
//System.out.printf("keys: %d, %s: %d\n", Arrays.hashCode(keys), _returnTypeClass, _returnTypeClass.hashCode());
thisHash = Arrays.hashCode(keys) ^ _returnTypeClass.hashCode();
keys = new ResultSetKey(super.getKeysFromResultSet(), _returnTypeClass);
//System.out.printf("keys: %s\n", keys);
} catch (SQLException e) {
throw new MapperException("CachingRowToObjectMapper: SQLException: " + e.getMessage(), e);
}
@ -28,32 +25,61 @@ public class CachingRowToObjectMapper<T> extends RowToObjectMapper<T> {
@Override
protected String[] getKeysFromResultSet() throws SQLException {
return keys;
return keys.keys;
}
@Override
protected void getFieldMappings() throws SQLException {
FieldMapping fm = cache.get(thisHash);
FieldMapping fm = cache.get(keys);
if (fm == null) {
//System.out.printf("cache miss, hashcode: %d\n", thisHash);
//System.out.printf("cache miss, keys: %s\n", keys);
// generate and put into cache
super.getFieldMappings();
synchronized (cache) {
// I *think* we only need to synchronize here, instead of around the get as well
// it may allow some leaks (field mappings being generated more than once)
// but the performance benefits of not having this entire method synchronized
// statically probably outweighs the negatives
cache.put(thisHash, new FieldMapping(_fields, _fieldTypes));
}
cache.put(keys, new FieldMapping(_fields, _fieldTypes));
} else {
//System.out.printf("cache hit, hashcode: %d\n", thisHash);
//System.out.printf("cache hit, keys: %s\n", keys);
// load from cache
_fields = fm._fields;
_fieldTypes = fm._fieldTypes;
}
}
private static class FieldMapping {
static class ResultSetKey {
protected final String[] keys;
protected final Class<?> returnTypeClass;
public ResultSetKey(final String[] keys, final Class<?> returnTypeClass) {
this.keys = keys;
this.returnTypeClass = returnTypeClass;
}
@Override
public boolean equals(final Object o) {
if (this == o) return true;
if (!(o instanceof ResultSetKey)) return false;
final ResultSetKey that = (ResultSetKey) o;
return Arrays.equals(keys, that.keys) && (returnTypeClass != null ? returnTypeClass.equals(that.returnTypeClass) : that.returnTypeClass == null);
}
@Override
public int hashCode() {
int result = Arrays.hashCode(keys);
result = 31 * result + (returnTypeClass != null ? returnTypeClass.hashCode() : 0);
return result;
}
@Override
public String toString() {
return "ResultSetKey{" +
"keys=" + Arrays.toString(keys) +
", returnTypeClass=" + returnTypeClass +
'}';
}
}
static class FieldMapping {
public final AccessibleObject[] _fields;
public final int[] _fieldTypes;

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