Estimates the size of attributes in the session

SakaiSessionEstimator

diff --git a/kernel/kernel-impl/pom.xml b/kernel/kernel-impl/pom.xml
index f5e5a64..b0b1d65 100644
--- a/kernel/kernel-impl/pom.xml
+++ b/kernel/kernel-impl/pom.xml
@@ -312,6 +312,11 @@
       <scope>compile</scope>
     </dependency>
     -->
+    <dependency>
+      <groupId>com.carrotsearch</groupId>
+      <artifactId>java-sizeof</artifactId>
+      <version>0.0.5</version>
+    </dependency>
     <!-- TESTING -->
     <dependency>
       <groupId>org.subethamail</groupId>
diff --git a/kernel/kernel-impl/src/main/java/org/sakaiproject/tool/impl/MyLittleSession.java b/kernel/kernel-impl/src/main/java/org/sakaiproject/tool/impl/MyLittleSession.java
index 786a771..f497d05 100644
--- a/kernel/kernel-impl/src/main/java/org/sakaiproject/tool/impl/MyLittleSession.java
+++ b/kernel/kernel-impl/src/main/java/org/sakaiproject/tool/impl/MyLittleSession.java
@@ -21,10 +21,17 @@
 package org.sakaiproject.tool.impl;
 
 import org.apache.commons.collections.iterators.IteratorChain;
+import org.apache.commons.lang.StringUtils;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.sakaiproject.component.cover.ServerConfigurationService;
 import org.sakaiproject.thread_local.api.ThreadLocalManager;
 import org.sakaiproject.tool.api.*;
 import org.sakaiproject.util.IteratorEnumeration;
 
+import com.carrotsearch.sizeof.ObjectTree;
+import com.carrotsearch.sizeof.RamUsageEstimator;
+
 import javax.servlet.ServletContext;
 import javax.servlet.http.HttpSession;
 import javax.servlet.http.HttpSessionBindingEvent;
@@ -33,6 +40,7 @@ import javax.servlet.http.HttpSessionContext;
 import java.io.Serializable;
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.regex.Pattern;
 
 /**********************************************************************************************************************************************************************************************************************************************************
  * Entity: ToolSession, ContextSession (and even HttpSession)
@@ -162,6 +170,8 @@ public class MyLittleSession implements ToolSession, ContextSession, HttpSession
 		TERRACOTTA_CLUSTER = "true".equals(clusterTerracotta);
 	}
 
+	private static Log LOG = LogFactory.getLog(MyLittleSession.class);
+
 	/**
 	 * @inheritDoc
 	 */
@@ -295,6 +305,37 @@ public class MyLittleSession implements ToolSession, ContextSession, HttpSession
 
 		else
 		{
+			if (LOG.isTraceEnabled()) {
+				// DO NOT USE this in a production system as calculating object sizes is very
+				// CPU intensive and is for debugging only. YOU HAVE BEEN WARNED.
+				String regex = ServerConfigurationService.getString("sizeof.session.tool.attributes.regex");
+				if (StringUtils.isBlank(regex)) {
+					// set a default value of everything
+					regex = ".*";
+				}
+
+				if (Pattern.matches(regex, name)) {
+					try {
+						long size = RamUsageEstimator.sizeOf(value);
+						StringBuilder msg = new StringBuilder("sizeOf [toolSession=>attribute]:[");
+						msg.append(this.m_littleId + "=>" + name + "] size is " + RamUsageEstimator.humanReadableUnits(size));
+						if (Pattern.matches(".*\\|dumpObjectTree$", regex)) {
+							// to get a dump of the object tree append dumpObjectTree to your regex
+							// .*|dumpObjectTree, also don't dump anything over 1MB
+							if (size <= 1048576 ) {
+								msg.append(", dumping object tree:\n");
+								msg.append(ObjectTree.dump(value));
+							} else {
+								msg.append(", object is over 1MB skipping dump\n");
+							}
+						}
+						LOG.trace(msg);
+					} catch(Exception e) {
+						LOG.error("sizeOf could not calculate the size of [toolSession=>attribute: " + this.m_id + "=>" + name + "]", e);
+					}
+				}
+			}
+
 			Object old = null;
 			
 			// If this is not a terracotta clustered environment then immediately
diff --git a/kernel/kernel-impl/src/main/java/org/sakaiproject/tool/impl/MySession.java b/kernel/kernel-impl/src/main/java/org/sakaiproject/tool/impl/MySession.java
index 3f33099..2db947d 100644
--- a/kernel/kernel-impl/src/main/java/org/sakaiproject/tool/impl/MySession.java
+++ b/kernel/kernel-impl/src/main/java/org/sakaiproject/tool/impl/MySession.java
@@ -22,7 +22,11 @@
 package org.sakaiproject.tool.impl;
 
 import org.apache.commons.collections.iterators.IteratorChain;
+import org.apache.commons.lang.StringUtils;
 import org.apache.commons.lang.mutable.MutableLong;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.sakaiproject.component.cover.ServerConfigurationService;
 import org.sakaiproject.event.api.UsageSession;
 import org.sakaiproject.id.api.IdManager;
 import org.sakaiproject.thread_local.api.ThreadLocalManager;
@@ -31,12 +35,16 @@ import org.sakaiproject.util.IteratorEnumeration;
 import org.sakaiproject.util.RequestFilter;
 import org.sakaiproject.util.ResourceLoader;
 
+import com.carrotsearch.sizeof.ObjectTree;
+import com.carrotsearch.sizeof.RamUsageEstimator;
+
 import javax.servlet.ServletContext;
 import javax.servlet.http.*;
 import java.io.Serializable;
 import java.lang.reflect.Array;
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.regex.Pattern;
 
 
 /*************************************************************************************************************************************************
@@ -147,6 +155,7 @@ public class MySession implements Session, HttpSession, Serializable
 		TERRACOTTA_CLUSTER = "true".equals(clusterTerracotta);
 	}
 
+	private static Log LOG = LogFactory.getLog(MySession.class);
 	/**
 	 * @inheritDoc
 	 */
@@ -511,6 +520,37 @@ public class MySession implements Session, HttpSession, Serializable
 
 		else
 		{
+			if (LOG.isTraceEnabled()) {
+				// DO NOT USE this in a production system as calculating object sizes is very
+				// CPU intensive and is for debugging only. YOU HAVE BEEN WARNED.
+				String regex = ServerConfigurationService.getString("sizeof.session.attributes.regex");
+				if (StringUtils.isBlank(regex)) {
+					// set a default value of everything
+					regex = ".*";
+				}
+
+				if (Pattern.matches(regex, name)) {
+					try {
+						long size = RamUsageEstimator.sizeOf(value);
+						StringBuilder msg = new StringBuilder("sizeOf [session=>attribute]:[");
+						msg.append(this.m_id + "=>" + name + "] size is " + RamUsageEstimator.humanReadableUnits(size));
+						if (Pattern.matches(".*\\|dumpObjectTree$", regex)) {
+							// to get a dump of the object tree append dumpObjectTree to your regex
+							// .*|dumpObjectTree, also don't dump anything over 1MB
+							if (size <= 1048576) {
+								msg.append(", dumping object tree:\n");
+								msg.append(ObjectTree.dump(value));
+							} else {
+								msg.append(", object is over 1MB skipping dump\n");
+							}
+						}
+						LOG.trace(msg);
+					} catch(Exception e) {
+						LOG.error("sizeOf could not calculate the size of [session=>attribute: " + this.m_id + "=>" + name + "]", e);
+					}
+				}
+			}
+
 			Object old = null;
 
 			// If this is not a terracotta clustered environment then immediately