Lob.INVALID_LOCATOR if LOB
* value was sent instead of locator
*/
- private int locator(int column)
+ protected int locator(int column)
{
int locator = get_INTEGER(column);
// If Lob value was sent instead of locator, the value will be
@@ -1078,6 +1078,7 @@
// Check for locator
int locator = locator(column);
if (locator > 0) { // Create locator-based LOB object
+ netResultSet_.keepLocatorColumnAlive(column);
return new Blob(agent, locator);
}
@@ -1112,6 +1113,7 @@
// Check for locator
int locator = locator(column);
if (locator > 0) { // Create locator-based LOB object
+ netResultSet_.keepLocatorColumnAlive(column);
return new Clob(agent, locator);
}
Index: java/client/org/apache/derby/client/am/Connection.java
===================================================================
--- java/client/org/apache/derby/client/am/Connection.java (revision 641363)
+++ java/client/org/apache/derby/client/am/Connection.java (working copy)
@@ -1031,6 +1031,13 @@
*/
protected abstract boolean supportsSessionDataCaching();
+ /**
+ * Checks whether the server supports locators for large objects.
+ *
+ * @return {@code true} if LOB locators are supported.
+ */
+ protected abstract boolean serverSupportsLocators();
+
public int getTransactionIsolation() throws SQLException {
// Store the current auto-commit value and use it to restore
Index: java/client/org/apache/derby/client/am/Statement.java
===================================================================
--- java/client/org/apache/derby/client/am/Statement.java (revision 641363)
+++ java/client/org/apache/derby/client/am/Statement.java (working copy)
@@ -1489,6 +1489,8 @@
}
resultSet.resultSetMetaData_ = resultSetMetaData_;
resultSet.resultSetMetaData_.resultSetConcurrency_ = resultSet.resultSetConcurrency_;
+ // Create tracker for locator LOB columns.
+ resultSet.createLOBColumnTracker();
// only cache the Cursor object for a PreparedStatement and if a Cursor object is
// not already cached.
Index: java/client/org/apache/derby/client/am/Cursor.java
===================================================================
--- java/client/org/apache/derby/client/am/Cursor.java (revision 641363)
+++ java/client/org/apache/derby/client/am/Cursor.java (working copy)
@@ -661,6 +661,27 @@
return recyclableCalendar_;
}
+ /**
+ * Returns a reference to the locator procedures.
+ * + * These procedures are used to operate on large objects referenced on the + * server by locators. + * + * @return The locator procedures object. + */ + CallableLocatorProcedures getLocatorProedures() { + return agent_.connection_.locatorProcedureCall(); + } + + /** + * Obtains the locator for the specified column. + * + * @param column 1-based column index + * @return A positive integer locator if valid, {@link Lob#INVALID_LOCATOR} + * otherwise. + */ + protected abstract int locator(int column); + abstract public Blob getBlobColumn_(int column, Agent agent) throws SqlException; abstract public Clob getClobColumn_(int column, Agent agent) throws SqlException; Index: java/client/org/apache/derby/client/am/NoOpLOBStateTracker.java =================================================================== --- java/client/org/apache/derby/client/am/NoOpLOBStateTracker.java (revision 0) +++ java/client/org/apache/derby/client/am/NoOpLOBStateTracker.java (revision 0) @@ -0,0 +1,51 @@ +/* + + Derby - Class org.apache.derby.client.am.NoOpLOBStateTracker + + 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.derby.client.am; + +import org.apache.derby.shared.common.sanity.SanityManager; + +/** + * A tracker implementation that does nothing, intended to be used when + * locators are not supported be the server. + */ +final class NoOpLOBStateTracker + extends LOBStateTracker { + + public NoOpLOBStateTracker() { + super(); + } + + void checkCurrentRow(Cursor ignore) { + // Does nothing. + } + + void noRelease(int ignore) { + // Does nothing. + if (SanityManager.DEBUG) { + SanityManager.THROWASSERT("NoOpLobStateTracker.noRelease should " + + "not be called when locators are not supported."); + } + } + + void discardState() { + // Does nothing. + } +} Property changes on: java/client/org/apache/derby/client/am/NoOpLOBStateTracker.java ___________________________________________________________________ Name: svn:eol-style + native Index: java/client/org/apache/derby/client/am/LOBStateTracker.java =================================================================== --- java/client/org/apache/derby/client/am/LOBStateTracker.java (revision 0) +++ java/client/org/apache/derby/client/am/LOBStateTracker.java (revision 0) @@ -0,0 +1,143 @@ +/* + + Derby - Class org.apache.derby.client.am.LOBStateTracker + + 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.derby.client.am; + +import java.util.Arrays; + +/** + * Tracks the state of large objects (LOBs) represented by locators in a + * result set. + *
+ * The state of LOBs must be tracked to ensure they are released on the server + * in a timely manner. If too many locators are kept upen, the assoicated + * resources on the server will consume too much memory. There are also other + * possible side effects, like holding on to locks for too long. + *
+ * Note that it only makes sense to use this class if locators are used. + * + * @see NoOpLOBStateTracker + */ +//@NotThreadSafe +class LOBStateTracker { + + private static final int UNKNOWN = -17; + private static final int IGNORE = -18; + + /** The columns indexes of the LOB columns. */ + private final int[] columns; + /** Tells whether a LOB is a Blob or a Clob. */ + private final boolean[] isBlob; + /** Status for the current row. */ + private final int[] rowStatus; + + LOBStateTracker(int[] lobColumns, boolean[] isBlob) { + this.columns = lobColumns; + this.isBlob = isBlob; + this.rowStatus = new int[lobColumns.length]; + Arrays.fill(this.rowStatus, UNKNOWN); + if (lobColumns.length != isBlob.length) { + throw new IllegalArgumentException("Index array must have same " + + "length as type array: " + lobColumns.length + " != " + + isBlob.length); + } + } + + /** + * Constructor used for no-op tracker implementations. + * + * @see NoOpLOBStateTracker + */ + protected LOBStateTracker() { + this.columns = null; + this.isBlob = null; + this.rowStatus = null; + } + + /** + * Marks the specified column of the current row as non-releasable. + *
+ * Columns must be marked as non-releasable when a LOB object is created, to + * avoid releasing the corresponding locator too early. + * + * @param index 1-based column index + */ + void noRelease(int index) { + // Locate the 1-based column index in the internal array and update + // the corresponding state entry. + for (int i=0; i < this.columns.length; i++) { + if (this.columns[i] == index) { + rowStatus[i] = IGNORE; + break; + } + } + } + + /** + * Checks the next row, updating state and freeing locators on the + * server if required. + * + * @param cursor the cursor object to use for freeing the locators + * @throws SqlException if freeing the locators on the server fails + */ + void checkCurrentRow(Cursor cursor) + throws SqlException { + final CallableLocatorProcedures procs = cursor.getLocatorProedures(); + // IMPLEMENTATION NOTE / OPTIMALIZATION: + // The block of code below is very naive, and can cause a round trip + // for each LOB for each rs.next (or other navigational method). + // There are two possible optimizations: + // (a) Implement a new stored procedure freeing a list of locators, + // and free locators when a threshold is reached. + // (b) Piggy-back list of locators on other requests. + // + // Optimization (a) is easy and will most likely be implemented right + // away. (b) is more complex, but frees resources optimally at almost no + // extra cost. + for (int i=0; i < this.columns.length; i++) { + if (this.rowStatus[i] == UNKNOWN) { + // Fetch locator so we can free it. + int locator = cursor.locator(this.columns[i]); + if (locator != Lob.INVALID_LOCATOR) { + if (this.isBlob[i]) { + procs.blobReleaseLocator(locator); + } else { + procs.clobReleaseLocator(locator); + } + } + } else { + // Reset state to unknown. + this.rowStatus[i] = UNKNOWN; + } + } + } + + /** + * Discards all recorded dynamic state about LOBs. + *
+ * Typically called on connection commit or rollback, as this will release + * all locators on the server automatically. There is no need to release + * them from the client side. + */ + void discardState() { + Arrays.fill(this.rowStatus, IGNORE); + } +} Property changes on: java/client/org/apache/derby/client/am/LOBStateTracker.java ___________________________________________________________________ Name: svn:eol-style + native Index: java/client/org/apache/derby/client/am/ResultSet.java =================================================================== --- java/client/org/apache/derby/client/am/ResultSet.java (revision 641363) +++ java/client/org/apache/derby/client/am/ResultSet.java (working copy) @@ -28,6 +28,7 @@ import org.apache.derby.client.am.SQLExceptionFactory; import org.apache.derby.shared.common.reference.SQLState; import org.apache.derby.shared.common.i18n.MessageUtil; +import org.apache.derby.shared.common.sanity.SanityManager; public abstract class ResultSet implements java.sql.ResultSet, ResultSetCallbackInterface { @@ -37,6 +38,7 @@ public ColumnMetaData resultSetMetaData_; // As obtained from the SQLDA private SqlWarning warnings_; public Cursor cursor_; + private LOBStateTracker lobState = null; protected Agent agent_; public Section generatedSection_ = null; @@ -426,6 +428,12 @@ if (!openOnClient_) { return; } + // See if there are open locators on the current row, if valid. + if (isValidCursorPosition_) { + lobState.checkCurrentRow(cursor_); + } + // NOTE: The preClose_ method must also check for locators if + // prefetching of data is enabled for result sets containing LOBs. preClose_(); try { if (openOnServer_) { @@ -3767,6 +3775,9 @@ } isValidCursorPosition_ = true; } + if (isValidCursorPosition_) { + lobState.checkCurrentRow(cursor_); + } } /** @@ -4338,6 +4349,7 @@ public void completeLocalCommit(java.util.Iterator listenerIterator) { cursorUnpositionedOnServer_ = true; + lobState.discardState(); // Locators released on server side. markAutoCommitted(); if (!cursorHold_) { // only non-held cursors need to be closed at commit @@ -4350,6 +4362,7 @@ } public void completeLocalRollback(java.util.Iterator listenerIterator) { + lobState.discardState(); // Locators released on server side. markAutoCommitted(); // all cursors need to be closed at rollback markClosed(); @@ -6173,4 +6186,44 @@ throw se.getSQLException(); } } + + public final void keepLocatorColumnAlive(int index) { + this.lobState.noRelease(index); + } + + final void createLOBColumnTracker() { + if (this.lobState != null) { + if (SanityManager.DEBUG) { + SanityManager.THROWASSERT( + "LOB state tracker already initialized."); + } + } + if (this.connection_.serverSupportsLocators() && + this.resultSetMetaData_.hasLobColumns()) { + final int columnCount = this.resultSetMetaData_.columns_; + int lobCount = 0; + int[] tmpIndexes = new int[columnCount]; + boolean[] tmpIsBlob = new boolean[columnCount]; + for (int i=0; i < columnCount; i++) { + int type = this.resultSetMetaData_.types_[i]; + if (type == Types.BLOB) { + tmpIndexes[lobCount] = i +1; // Convert to 1-based index. + tmpIsBlob[lobCount++] = true; + } else if (type == Types.CLOB) { + tmpIndexes[lobCount] = i +1; // Convert to 1-based index. + tmpIsBlob[lobCount++] = false; + } + } + // Create a tracker for the LOB columns found. + int[] lobIndexes = new int[lobCount]; + boolean[] isBlob = new boolean[lobCount]; + System.arraycopy(tmpIndexes, 0, lobIndexes, 0, lobCount); + System.arraycopy(tmpIsBlob, 0, isBlob, 0, lobCount); + this.lobState = new LOBStateTracker(lobIndexes, isBlob); + } else { + // Create a tracker that does nothing. + // Done to simplify code expecting a tracker object. + this.lobState = new NoOpLOBStateTracker(); + } + } }