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The core jetty server artifact.
//
// ========================================================================
// Copyright (c) 1995-2022 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
// which is available at https://www.apache.org/licenses/LICENSE-2.0.
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//
package org.eclipse.jetty.server.session;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Function;
import jakarta.servlet.http.HttpServletRequest;
import org.eclipse.jetty.util.StringUtil;
import org.eclipse.jetty.util.annotation.ManagedAttribute;
import org.eclipse.jetty.util.annotation.ManagedObject;
import org.eclipse.jetty.util.component.ContainerLifeCycle;
import org.eclipse.jetty.util.thread.AutoLock;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* AbstractSessionCache
*
* A base implementation of the {@link SessionCache} interface for managing a set of
* Session objects pertaining to a context in memory.
*
* This implementation ensures that multiple requests for the same session id
* always return the same Session object.
*
* It will delay writing out a session to the SessionDataStore until the
* last request exits the session. If the SessionDataStore supports passivation
* then the session passivation and activation listeners are called appropriately as
* the session is written.
*
* This implementation also supports evicting idle Session objects. An idle Session
* is one that is still valid, has not expired, but has not been accessed by a
* request for a configurable amount of time. An idle session will be first
* passivated before it is evicted from the cache.
*/
@ManagedObject
public abstract class AbstractSessionCache extends ContainerLifeCycle implements SessionCache
{
private static final Logger LOG = LoggerFactory.getLogger(AbstractSessionCache.class);
/**
* The authoritative source of session data
*/
protected SessionDataStore _sessionDataStore;
/**
* The SessionHandler related to this SessionCache
*/
protected final SessionHandler _handler;
/**
* Information about the context to which this SessionCache pertains
*/
protected SessionContext _context;
/**
* When, if ever, to evict sessions: never; only when the last request for them finishes; after inactivity time (expressed as secs)
*/
protected int _evictionPolicy = SessionCache.NEVER_EVICT;
/**
* If true, as soon as a new session is created, it will be persisted to the SessionDataStore
*/
protected boolean _saveOnCreate = false;
/**
* If true, a session that will be evicted from the cache because it has been
* inactive too long will be saved before being evicted.
*/
protected boolean _saveOnInactiveEviction;
/**
* If true, a Session whose data cannot be read will be
* deleted from the SessionDataStore.
*/
protected boolean _removeUnloadableSessions;
/**
* If true, when a response is about to be committed back to the client,
* a dirty session will be flushed to the session store.
*/
protected boolean _flushOnResponseCommit;
/**
* If true, when the server shuts down, all sessions in the
* cache will be invalidated before being removed.
*/
protected boolean _invalidateOnShutdown;
/**
* Create a new Session object from pre-existing session data
*
* @param data the session data
* @return a new Session object
*/
@Override
public abstract Session newSession(SessionData data);
/**
* Create a new Session for a request.
*
* @param request the request
* @param data the session data
* @return the new session
*/
public abstract Session newSession(HttpServletRequest request, SessionData data);
/**
* Get the session matching the key from the cache. Does not load
* the session.
*
* @param id session id
* @return the Session object matching the id
*/
protected abstract Session doGet(String id);
/**
* Put the session into the map if it wasn't already there
*
* @param id the identity of the session
* @param session the session object
* @return null if the session wasn't already in the map, or the existing entry otherwise
*/
protected abstract Session doPutIfAbsent(String id, Session session);
/**
* Compute the mappingFunction to create a Session object iff the session
* with the given id isn't already in the map, otherwise return the existing Session.
* This method is expected to have precisely the same behaviour as
* {@link java.util.concurrent.ConcurrentHashMap#computeIfAbsent}
*
* @param id the session id
* @param mappingFunction the function to load the data for the session
* @return an existing Session from the cache
*/
protected abstract Session doComputeIfAbsent(String id, Function mappingFunction);
/**
* Replace the mapping from id to oldValue with newValue
*
* @param id the id
* @param oldValue the old value
* @param newValue the new value
* @return true if replacement was done
*/
protected abstract boolean doReplace(String id, Session oldValue, Session newValue);
/**
* Remove the session with this identity from the store
*
* @param id the id
* @return Session that was removed or null
*/
public abstract Session doDelete(String id);
/**
* @param handler the {@link SessionHandler} to use
*/
public AbstractSessionCache(SessionHandler handler)
{
_handler = handler;
}
/**
* @return the SessionManger
*/
@Override
public SessionHandler getSessionHandler()
{
return _handler;
}
@Override
public void initialize(SessionContext context)
{
if (isStarted())
throw new IllegalStateException("Context set after session store started");
_context = context;
}
@Override
protected void doStart() throws Exception
{
if (_sessionDataStore == null)
throw new IllegalStateException("No session data store configured");
if (_handler == null)
throw new IllegalStateException("No session manager");
if (_context == null)
throw new IllegalStateException("No ContextId");
_sessionDataStore.initialize(_context);
super.doStart();
}
@Override
protected void doStop() throws Exception
{
_sessionDataStore.stop();
super.doStop();
}
/**
* @return the SessionDataStore or null if there isn't one
*/
@Override
public SessionDataStore getSessionDataStore()
{
return _sessionDataStore;
}
@Override
public void setSessionDataStore(SessionDataStore sessionStore)
{
updateBean(_sessionDataStore, sessionStore);
_sessionDataStore = sessionStore;
}
/**
* @see org.eclipse.jetty.server.session.SessionCache#getEvictionPolicy()
*/
@ManagedAttribute(value = "session eviction policy", readonly = true)
@Override
public int getEvictionPolicy()
{
return _evictionPolicy;
}
/**
* -1 means we never evict inactive sessions.
* 0 means we evict a session after the last request for it exits
* >0 is the number of seconds after which we evict inactive sessions from the cache
*
* @see org.eclipse.jetty.server.session.SessionCache#setEvictionPolicy(int)
*/
@Override
public void setEvictionPolicy(int evictionTimeout)
{
_evictionPolicy = evictionTimeout;
}
@ManagedAttribute(value = "immediately save new sessions", readonly = true)
@Override
public boolean isSaveOnCreate()
{
return _saveOnCreate;
}
@Override
public void setSaveOnCreate(boolean saveOnCreate)
{
_saveOnCreate = saveOnCreate;
}
/**
* @return true if sessions that can't be loaded are deleted from the store
*/
@ManagedAttribute(value = "delete unreadable stored sessions", readonly = true)
@Override
public boolean isRemoveUnloadableSessions()
{
return _removeUnloadableSessions;
}
/**
* If a session's data cannot be loaded from the store without error, remove
* it from the persistent store.
*
* @param removeUnloadableSessions if true unloadable sessions will be removed from session store
*/
@Override
public void setRemoveUnloadableSessions(boolean removeUnloadableSessions)
{
_removeUnloadableSessions = removeUnloadableSessions;
}
@Override
public void setFlushOnResponseCommit(boolean flushOnResponseCommit)
{
_flushOnResponseCommit = flushOnResponseCommit;
}
@Override
public boolean isFlushOnResponseCommit()
{
return _flushOnResponseCommit;
}
/**
* Get a session object.
*
* If the session object is not in this session store, try getting
* the data for it from a SessionDataStore associated with the
* session manager. The usage count of the session is incremented.
*
* @see org.eclipse.jetty.server.session.SessionCache#get(java.lang.String)
*/
@Override
public Session get(String id) throws Exception
{
return getAndEnter(id, true);
}
/** Get a session object.
*
* If the session object is not in this session store, try getting
* the data for it from a SessionDataStore associated with the
* session manager.
*
* @param id The session to retrieve
* @param enter if true, the usage count of the session will be incremented
* @return the session if it exists, null otherwise
* @throws Exception if the session cannot be loaded
*/
protected Session getAndEnter(String id, boolean enter) throws Exception
{
Session session = null;
AtomicReference exception = new AtomicReference();
session = doComputeIfAbsent(id, k ->
{
if (LOG.isDebugEnabled())
LOG.debug("Session {} not found locally in {}, attempting to load", id, this);
try
{
Session s = loadSession(k);
if (s != null)
{
try (AutoLock lock = s.lock())
{
s.setResident(true); //ensure freshly loaded session is resident
}
}
else
{
if (LOG.isDebugEnabled())
LOG.debug("Session {} not loaded by store", id);
}
return s;
}
catch (Exception e)
{
exception.set(e);
return null;
}
});
Exception ex = exception.get();
if (ex != null)
throw ex;
if (session != null)
{
try (AutoLock lock = session.lock())
{
if (!session.isResident()) //session isn't marked as resident in cache
{
if (LOG.isDebugEnabled())
LOG.debug("Non-resident session {} in cache", id);
return null;
}
else if (enter)
{
session.use();
}
}
}
return session;
}
/**
* Load the info for the session from the session data store
*
* @param id the id
* @return a Session object filled with data or null if the session doesn't exist
*/
private Session loadSession(String id)
throws Exception
{
SessionData data = null;
Session session = null;
if (_sessionDataStore == null)
return null; //can't load it
try
{
data = _sessionDataStore.load(id);
if (data == null) //session doesn't exist
return null;
data.setLastNode(_context.getWorkerName()); //we are going to manage the node
session = newSession(data);
return session;
}
catch (UnreadableSessionDataException e)
{
//can't load the session, delete it
if (isRemoveUnloadableSessions())
_sessionDataStore.delete(id);
throw e;
}
}
/**
* Add an entirely new session (created by the application calling Request.getSession(true))
* to the cache. The usage count of the fresh session is incremented.
*
* @param id the id
* @param session
*/
@Override
public void add(String id, Session session) throws Exception
{
if (id == null || session == null)
throw new IllegalArgumentException("Add key=" + id + " session=" + (session == null ? "null" : session.getId()));
try (AutoLock lock = session.lock())
{
if (session.getSessionHandler() == null)
throw new IllegalStateException("Session " + id + " is not managed");
if (!session.isValid())
throw new IllegalStateException("Session " + id + " is not valid");
if (doPutIfAbsent(id, session) == null)
{
session.setResident(true); //its in the cache
session.use(); //the request is using it
}
else
throw new IllegalStateException("Session " + id + " already in cache");
}
}
/**
* A response that has accessed this session is about to
* be returned to the client. Pass the session to the store
* to persist, so that any changes will be visible to
* subsequent requests on the same node (if using NullSessionCache),
* or on other nodes.
*/
@Override
public void commit(Session session) throws Exception
{
if (session == null)
return;
try (AutoLock lock = session.lock())
{
//only write the session out at this point if the attributes changed. If only
//the lastAccess/expiry time changed defer the write until the last request exits
if (session.isValid() && session.getSessionData().isDirty() && _flushOnResponseCommit)
{
if (LOG.isDebugEnabled())
LOG.debug("Flush session {} on response commit", session);
//save the session
if (!_sessionDataStore.isPassivating())
{
_sessionDataStore.store(session.getId(), session.getSessionData());
}
else
{
session.willPassivate();
_sessionDataStore.store(session.getId(), session.getSessionData());
session.didActivate();
}
}
}
}
/**
* @deprecated use {@link #release(String, Session)} instead
*/
@Override
@Deprecated
public void put(String id, Session session) throws Exception
{
release(id, session);
}
/**
* Finish using the Session object.
*
* This should be called when a request exists the session. Only when the last
* simultaneous request exists the session will any action be taken.
*
* If there is a SessionDataStore write the session data through to it.
*
* If the SessionDataStore supports passivation, call the passivate/active listeners.
*
* If the evictionPolicy == SessionCache.EVICT_ON_SESSION_EXIT then after we have saved
* the session, we evict it from the cache.
*
* @see org.eclipse.jetty.server.session.SessionCache#release(java.lang.String, org.eclipse.jetty.server.session.Session)
*/
@Override
public void release(String id, Session session) throws Exception
{
if (id == null || session == null)
throw new IllegalArgumentException("Put key=" + id + " session=" + (session == null ? "null" : session.getId()));
try (AutoLock lock = session.lock())
{
if (session.getSessionHandler() == null)
throw new IllegalStateException("Session " + id + " is not managed");
if (session.isInvalid())
return;
session.complete();
//don't do anything with the session until the last request for it has finished
if ((session.getRequests() <= 0))
{
//reset the idchanged flag
session.setIdChanged(false);
//save the session
if (!_sessionDataStore.isPassivating())
{
//if our backing datastore isn't the passivating kind, just save the session
_sessionDataStore.store(id, session.getSessionData());
//if we evict on session exit, boot it from the cache
if (getEvictionPolicy() == EVICT_ON_SESSION_EXIT)
{
if (LOG.isDebugEnabled())
LOG.debug("Eviction on request exit id={}", id);
doDelete(session.getId());
session.setResident(false);
}
else
{
session.setResident(true);
doPutIfAbsent(id, session); //ensure it is in our map
if (LOG.isDebugEnabled())
LOG.debug("Non passivating SessionDataStore, session in SessionCache only id={}", id);
}
}
else
{
//backing store supports passivation, call the listeners
session.willPassivate();
if (LOG.isDebugEnabled())
LOG.debug("Session passivating id={}", id);
_sessionDataStore.store(id, session.getSessionData());
if (getEvictionPolicy() == EVICT_ON_SESSION_EXIT)
{
//throw out the passivated session object from the map
doDelete(id);
session.setResident(false);
if (LOG.isDebugEnabled())
LOG.debug("Evicted on request exit id={}", id);
}
else
{
//reactivate the session
session.didActivate();
session.setResident(true);
doPutIfAbsent(id, session); //ensure it is in our map
if (LOG.isDebugEnabled())
LOG.debug("Session reactivated id={}", id);
}
}
}
else
{
if (LOG.isDebugEnabled())
LOG.debug("Req count={} for id={}", session.getRequests(), id);
session.setResident(true);
doPutIfAbsent(id, session); //ensure it is the map, but don't save it to the backing store until the last request exists
}
}
}
/**
* Check to see if a session corresponding to the id exists.
*
* This method will first check with the object store. If it
* doesn't exist in the object store (might be passivated etc),
* it will check with the data store.
*
* @throws Exception the Exception
* @see org.eclipse.jetty.server.session.SessionCache#exists(java.lang.String)
*/
@Override
public boolean exists(String id) throws Exception
{
//try the object store first
Session s = doGet(id);
if (s != null)
{
try (AutoLock lock = s.lock())
{
//wait for the lock and check the validity of the session
return s.isValid();
}
}
//not there, so find out if session data exists for it
return _sessionDataStore.exists(id);
}
/**
* Check to see if this cache contains an entry for the session
* corresponding to the session id.
*
* @see org.eclipse.jetty.server.session.SessionCache#contains(java.lang.String)
*/
@Override
public boolean contains(String id) throws Exception
{
//just ask our object cache, not the store
return (doGet(id) != null);
}
/**
* Remove a session object from this store and from any backing store.
*
* @see org.eclipse.jetty.server.session.SessionCache#delete(java.lang.String)
*/
@Override
public Session delete(String id) throws Exception
{
//get the session, if its not in memory, this will load it
Session session = getAndEnter(id, false);
//Always delete it from the backing data store
if (_sessionDataStore != null)
{
boolean dsdel = _sessionDataStore.delete(id);
if (LOG.isDebugEnabled())
LOG.debug("Session id={} deleted in session data store {}", id, dsdel);
}
//delete it from the session object store
if (session != null)
{
session.setResident(false);
}
return doDelete(id);
}
@Override
public Set checkExpiration(Set candidates)
{
if (!isStarted())
return Collections.emptySet();
if (LOG.isDebugEnabled())
LOG.debug("{} checking expiration on {}", this, candidates);
Set allCandidates = _sessionDataStore.getExpired(candidates);
Set sessionsInUse = new HashSet<>();
if (allCandidates != null)
{
for (String c : allCandidates)
{
Session s = doGet(c);
if (s != null && s.getRequests() > 0) //if the session is in my cache, check its not in use first
sessionsInUse.add(c);
}
try
{
allCandidates.removeAll(sessionsInUse);
}
catch (UnsupportedOperationException e)
{
Set tmp = new HashSet<>(allCandidates);
tmp.removeAll(sessionsInUse);
allCandidates = tmp;
}
}
return allCandidates;
}
/**
* Check a session for being inactive and
* thus being able to be evicted, if eviction
* is enabled.
*
* @param session session to check
*/
@Override
public void checkInactiveSession(Session session)
{
if (session == null)
return;
if (LOG.isDebugEnabled())
LOG.debug("Checking for idle {}", session.getId());
try (AutoLock s = session.lock())
{
if (getEvictionPolicy() > 0 && session.isIdleLongerThan(getEvictionPolicy()) &&
session.isValid() && session.isResident() && session.getRequests() <= 0)
{
//Be careful with saveOnInactiveEviction - you may be able to re-animate a session that was
//being managed on another node and has expired.
try
{
if (LOG.isDebugEnabled())
LOG.debug("Evicting idle session {}", session.getId());
//save before evicting
if (isSaveOnInactiveEviction() && _sessionDataStore != null)
{
if (_sessionDataStore.isPassivating())
session.willPassivate();
//Fake being dirty to force the write
session.getSessionData().setDirty(true);
_sessionDataStore.store(session.getId(), session.getSessionData());
}
doDelete(session.getId()); //detach from this cache
session.setResident(false);
}
catch (Exception e)
{
LOG.warn("Passivation of idle session {} failed", session.getId(), e);
}
}
}
}
@Override
public Session renewSessionId(String oldId, String newId, String oldExtendedId, String newExtendedId)
throws Exception
{
if (StringUtil.isBlank(oldId))
throw new IllegalArgumentException("Old session id is null");
if (StringUtil.isBlank(newId))
throw new IllegalArgumentException("New session id is null");
Session session = getAndEnter(oldId, true);
renewSessionId(session, newId, newExtendedId);
return session;
}
/**
* Swap the id on a session.
*
* @param session the session for which to do the swap
* @param newId the new id
* @param newExtendedId the full id plus node id
* @throws Exception if there was a failure saving the change
*/
protected void renewSessionId(Session session, String newId, String newExtendedId)
throws Exception
{
if (session == null)
return;
try (AutoLock lock = session.lock())
{
String oldId = session.getId();
session.checkValidForWrite(); //can't change id on invalid session
session.getSessionData().setId(newId);
session.getSessionData().setLastSaved(0); //pretend that the session has never been saved before to get a full save
session.getSessionData().setDirty(true); //ensure we will try to write the session out
session.setExtendedId(newExtendedId); //remember the new extended id
session.setIdChanged(true); //session id changed
doPutIfAbsent(newId, session); //put the new id into our map
doDelete(oldId); //take old out of map
if (_sessionDataStore != null)
{
_sessionDataStore.delete(oldId); //delete the session data with the old id
_sessionDataStore.store(newId, session.getSessionData()); //save the session data with the new id
}
if (LOG.isDebugEnabled())
LOG.debug("Session id={} swapped for new id={}", oldId, newId);
}
}
@Override
public void setSaveOnInactiveEviction(boolean saveOnEvict)
{
_saveOnInactiveEviction = saveOnEvict;
}
@Override
public void setInvalidateOnShutdown(boolean invalidateOnShutdown)
{
_invalidateOnShutdown = invalidateOnShutdown;
}
@Override
public boolean isInvalidateOnShutdown()
{
return _invalidateOnShutdown;
}
/**
* Whether we should save a session that has been inactive before
* we boot it from the cache.
*
* @return true if an inactive session will be saved before being evicted
*/
@ManagedAttribute(value = "save sessions before evicting from cache", readonly = true)
@Override
public boolean isSaveOnInactiveEviction()
{
return _saveOnInactiveEviction;
}
@Override
public Session newSession(HttpServletRequest request, String id, long time, long maxInactiveMs)
{
if (LOG.isDebugEnabled())
LOG.debug("Creating new session id={}", id);
Session session = newSession(request, _sessionDataStore.newSessionData(id, time, time, time, maxInactiveMs));
session.getSessionData().setLastNode(_context.getWorkerName());
try
{
if (isSaveOnCreate() && _sessionDataStore != null)
_sessionDataStore.store(id, session.getSessionData());
}
catch (Exception e)
{
LOG.warn("Save of new session {} failed", id, e);
}
return session;
}
@Override
public String toString()
{
return String.format("%s@%x[evict=%d,removeUnloadable=%b,saveOnCreate=%b,saveOnInactiveEvict=%b]",
this.getClass().getName(), this.hashCode(), _evictionPolicy,
_removeUnloadableSessions, _saveOnCreate, _saveOnInactiveEviction);
}
}