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1. Serialization/deserialization happens in the sessionStore, the utility class only handles the DB operations. 2. SessionTableAttributes was completely removed 3. ExpiredSessionReaper was completely removed 4. The serialization/deserialization happens with Tomcat's own methods. 5. The DB structure was simplified. Only a key (sessionID) and the serialized session data are stored. (Tomcat's reaper needs no more, it checks the expiration date in the deserialized session object) 6 A DB synchronization added to the keys() method (It refresh the keys in each hour from the DB). #19

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merged 1 commit into from
Apr 2, 2015
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1. Serialization/deserialization happens in the sessionStore, the utility class only handles the DB operations. 2. SessionTableAttributes was completely removed 3. ExpiredSessionReaper was completely removed 4. The serialization/deserialization happens with Tomcat's own methods. 5. The DB structure was simplified. Only a key (sessionID) and the serialized session data are stored. (Tomcat's reaper needs no more, it checks the expiration date in the deserialized session object) 6 A DB synchronization added to the keys() method (It refresh the keys in each hour from the DB). #19

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8 changes: 4 additions & 4 deletions pom.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@
<artifactId>aws-dynamodb-session-tomcat</artifactId>
<packaging>jar</packaging>
<name>Amazon DynamoDB Session Manager for Tomcat</name>
<version>1.0.2</version>
<version>1.2</version>
<description>The Amazon DynamoDB Session Manager for Tomcat provides a custom session manager for Tomcat 7 that stores session data in Amazon DynamoDB, Amazon's fully managed NoSQL database service.</description>
<url>https://aws.amazon.com/java</url>

Expand Down Expand Up @@ -42,7 +42,7 @@
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>tomcat-catalina</artifactId>
<version>7.0.42</version>
<version>7.0.47</version>
</dependency>
</dependencies>

Expand All @@ -64,8 +64,8 @@
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3</version>
<configuration>
<source>1.5</source>
<target>1.5</target>
<source>1.7</source>
<target>1.7</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
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6 changes: 1 addition & 5 deletions src/main/java/com/amazonaws/services/dynamodb/sessionmanager/DynamoDBSessionManager.java
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Expand Up @@ -39,7 +39,7 @@ public class DynamoDBSessionManager extends PersistentManagerBase {
private static final String DEFAULT_TABLE_NAME = "Tomcat_SessionState";

private static final String name = "AmazonDynamoDBSessionManager";
private static final String info = name + "/1.0";
private static final String info = name + "/2.0";

private String regionId = "us-east-1";
private String endpoint;
Expand All @@ -53,8 +53,6 @@ public class DynamoDBSessionManager extends PersistentManagerBase {

private final DynamoDBSessionStore dynamoSessionStore;

private ExpiredSessionReaper expiredSessionReaper;

private static Log logger;


Expand Down Expand Up @@ -143,13 +141,11 @@ protected void initInternal() throws LifecycleException {
dynamoSessionStore.setDynamoClient(dynamo);
dynamoSessionStore.setSessionTableName(this.tableName);

expiredSessionReaper = new ExpiredSessionReaper(dynamo, tableName, this.maxInactiveInterval);
}

@Override
protected synchronized void stopInternal() throws LifecycleException {
super.stopInternal();
if (expiredSessionReaper != null) expiredSessionReaper.shutdown();
}

private void initDynamoTable(AmazonDynamoDBClient dynamo) {
Expand Down
292 changes: 176 additions & 116 deletions src/main/java/com/amazonaws/services/dynamodb/sessionmanager/DynamoDBSessionStore.java
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Expand Up @@ -14,23 +14,28 @@
*/
package com.amazonaws.services.dynamodb.sessionmanager;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.nio.ByteBuffer;
import java.util.Collections;
import java.util.HashSet;
import java.util.Map;
import java.util.List;
import java.util.Set;

import org.apache.catalina.Container;
import org.apache.catalina.Loader;
import org.apache.catalina.Session;
import org.apache.catalina.session.StandardSession;
import org.apache.catalina.session.StoreBase;
import org.apache.catalina.util.CustomObjectInputStream;

import com.amazonaws.services.dynamodb.sessionmanager.util.DynamoUtils;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient;
import com.amazonaws.services.dynamodbv2.model.AttributeValue;
import com.amazonaws.services.dynamodbv2.model.DescribeTableRequest;
import com.amazonaws.services.dynamodbv2.model.TableDescription;

Expand All @@ -40,118 +45,173 @@
*/
public class DynamoDBSessionStore extends StoreBase {

private static final String name = "AmazonDynamoDBSessionStore";
private static final String info = name + "/1.0";

private AmazonDynamoDBClient dynamo;
private String sessionTableName;

private Set<String> keys = Collections.synchronizedSet(new HashSet<String>());


@Override
public String getInfo() {
return info;
}

@Override
public String getStoreName() {
return name;
}

public void setDynamoClient(AmazonDynamoDBClient dynamo) {
this.dynamo = dynamo;
}

public void setSessionTableName(String tableName) {
this.sessionTableName = tableName;
}


@Override
public void clear() throws IOException {
final Set<String> keysCopy = new HashSet<String>();
keysCopy.addAll(keys);

new Thread("dynamodb-session-manager-clear") {
@Override
public void run() {
for (String sessionId : keysCopy) {
DynamoUtils.deleteSession(dynamo, sessionTableName, sessionId);
}
}
}.start();

keys.clear();
}

@Override
public int getSize() throws IOException {
// The item count from describeTable is updated every ~6 hours
TableDescription table = dynamo.describeTable(new DescribeTableRequest().withTableName(sessionTableName)).getTable();
long itemCount = table.getItemCount();

return (int)itemCount;
}

@Override
public String[] keys() throws IOException {
return keys.toArray(new String[0]);
}

@Override
public Session load(String id) throws ClassNotFoundException, IOException {
Map<String, AttributeValue> item = DynamoUtils.loadItemBySessionId(dynamo, sessionTableName, id);
if (item == null || !item.containsKey(SessionTableAttributes.SESSION_ID_KEY) || !item.containsKey(SessionTableAttributes.SESSION_DATA_ATTRIBUTE)) {
DynamoDBSessionManager.warn("Unable to load session attributes for session " + id);
return null;
}


Session session = getManager().createSession(id);
session.setCreationTime(Long.parseLong(item.get(SessionTableAttributes.CREATED_AT_ATTRIBUTE).getN()));


ByteBuffer byteBuffer = item.get(SessionTableAttributes.SESSION_DATA_ATTRIBUTE).getB();
ByteArrayInputStream inputStream = new ByteArrayInputStream(byteBuffer.array());

Object readObject;
CustomObjectInputStream objectInputStream = null;
try {
Container webapp = getManager().getContainer();
objectInputStream = new CustomObjectInputStream(inputStream, webapp.getLoader().getClassLoader());

readObject = objectInputStream.readObject();
} finally {
try { objectInputStream.close(); } catch (Exception e) {}
}

if (readObject instanceof Map<?, ?>) {
Map<String, Object> sessionAttributeMap = (Map<String, Object>)readObject;

for (String s : sessionAttributeMap.keySet()) {
((StandardSession)session).setAttribute(s, sessionAttributeMap.get(s));
}
} else {
throw new RuntimeException("Error: Unable to unmarshall session attributes from DynamoDB store");
}


keys.add(id);
manager.add(session);

return session;
}

@Override
public void save(Session session) throws IOException {
DynamoUtils.storeSession(dynamo, sessionTableName, session);
keys.add(session.getId());
}

@Override
public void remove(String id) throws IOException {
DynamoUtils.deleteSession(dynamo, sessionTableName, id);
keys.remove(id);
}
private static final String name = "AmazonDynamoDBSessionStore";
private static final String info = name + "/1.0";

private AmazonDynamoDBClient dynamo;
private String sessionTableName;

private Set<String> keys = Collections.synchronizedSet(new HashSet<String>());
private long keysTimestamp=0;

@Override
public String getInfo() {
return info;
}

@Override
public String getStoreName() {
return name;
}

public void setDynamoClient(AmazonDynamoDBClient dynamo) {
this.dynamo = dynamo;
}

public void setSessionTableName(String tableName) {
this.sessionTableName = tableName;
}

@Override
public void clear() throws IOException {
final Set<String> keysCopy = new HashSet<String>();
keysCopy.addAll(keys);

new Thread("dynamodb-session-manager-clear") {
@Override
public void run() {
for (String sessionId : keysCopy) {
remove(sessionId);
}
}
}.start();

}

@Override
public int getSize() throws IOException {
TableDescription table = dynamo.describeTable(new DescribeTableRequest().withTableName(sessionTableName))
.getTable();
long itemCount = table.getItemCount();

return (int) itemCount;
}

@Override
public String[] keys() throws IOException {
// refresh the keys stored in memory in every hour.
if(keysTimestamp<System.currentTimeMillis()-1000L*60*60) {
// Other instances can also add or remove sessions, so we have to synchronise the keys set with the DB sometimes
List<String> list=DynamoUtils.loadKeys(dynamo, sessionTableName);
keys.clear();
keys.addAll(list);
keysTimestamp=System.currentTimeMillis();
}

return keys.toArray(new String[0]);

}

@Override
public Session load(String id) throws ClassNotFoundException, IOException {

ByteBuffer byteBuffer = DynamoUtils.loadItemBySessionId(dynamo, sessionTableName, id);
if (byteBuffer == null) {
keys.remove(id);
return (null);
}

if (manager.getContainer().getLogger().isDebugEnabled()) {
manager.getContainer().getLogger().debug(sm.getString(getStoreName() + ".loading", id, sessionTableName));
}

ByteArrayInputStream fis = null;
BufferedInputStream bis = null;
ObjectInputStream ois = null;
Loader loader = null;
ClassLoader classLoader = null;
try {
fis = new ByteArrayInputStream(byteBuffer.array());
bis = new BufferedInputStream(fis);
Container container = manager.getContainer();
if (container != null) {
loader = container.getLoader();
}
if (loader != null) {
classLoader = loader.getClassLoader();
}
if (classLoader != null) {
ois = new CustomObjectInputStream(bis, classLoader);
} else {
ois = new ObjectInputStream(bis);
}
} catch (Exception e) {
if (bis != null) {
try {
bis.close();
} catch (IOException f) {
}
}
if (fis != null) {
try {
fis.close();
} catch (IOException f) {
}
}
throw e;
}

try {
StandardSession session = (StandardSession) manager.createEmptySession();
session.readObjectData(ois);
session.setManager(manager);
keys.add(id);
return (session);
} finally {
try {
ois.close();
} catch (IOException f) {
}
}
}

@Override
public void save(Session session) throws IOException {

String id = session.getIdInternal();

if (manager.getContainer().getLogger().isDebugEnabled()) {
manager.getContainer().getLogger()
.debug(sm.getString(getStoreName() + ".saving", id, sessionTableName));
}

ByteArrayOutputStream fos = new ByteArrayOutputStream();
ObjectOutputStream oos = null;
try {
oos = new ObjectOutputStream(new BufferedOutputStream(fos));
} catch (IOException e) {
try {
fos.close();
} catch (IOException f) {
}
throw e;
}

try {
((StandardSession) session).writeObjectData(oos);
} finally {
oos.close();
}
DynamoUtils.storeSession(dynamo, sessionTableName, id, ByteBuffer.wrap(fos.toByteArray()));
keys.add(id);
}

@Override
public void remove(String id) {
if (manager.getContainer().getLogger().isDebugEnabled()) {
manager.getContainer().getLogger().debug(sm.getString(getStoreName() + ".removing", id, sessionTableName));
}
DynamoUtils.deleteSession(dynamo, sessionTableName, id);
keys.remove(id);
}
}
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