# ThrottleMediator.java

    /*
     *  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.synapse.mediators.throttle;

    import org.apache.axiom.om.OMElement;
    import org.apache.axis2.clustering.ClusteringAgent;
    import org.apache.axis2.context.ConfigurationContext;
    import org.apache.neethi.PolicyEngine;
    import org.apache.synapse.*;
    import org.apache.synapse.MessageContext;
    import org.apache.synapse.aspects.AspectConfiguration;
    import org.apache.synapse.aspects.ComponentType;
    import org.apache.synapse.aspects.flow.statistics.StatisticIdentityGenerator;
    import org.apache.synapse.aspects.flow.statistics.collectors.RuntimeStatisticCollector;
    import org.apache.synapse.aspects.flow.statistics.data.artifact.ArtifactHolder;
    import org.apache.synapse.config.Entry;
    import org.apache.synapse.config.SynapseConfiguration;
    import org.apache.synapse.continuation.ContinuationStackManager;
    import org.apache.synapse.continuation.ReliantContinuationState;
    import org.apache.synapse.core.axis2.Axis2MessageContext;
    import org.apache.synapse.core.SynapseEnvironment;
    import org.apache.synapse.core.axis2.Axis2SynapseEnvironment;
    import org.apache.synapse.debug.constructs.EnclosedInlinedSequence;
    import org.apache.synapse.mediators.AbstractMediator;
    import org.apache.synapse.mediators.FlowContinuableMediator;
    import org.apache.synapse.mediators.base.SequenceMediator;
    import org.apache.synapse.rest.RESTConstants;
    import org.apache.synapse.transport.nhttp.NhttpConstants;
    import org.apache.synapse.commons.throttle.core.AccessRateController;
    import org.apache.synapse.commons.throttle.core.ConcurrentAccessController;
    import org.apache.synapse.commons.throttle.core.ConcurrentAccessReplicator;
    import org.apache.synapse.commons.throttle.core.Throttle;
    import org.apache.synapse.commons.throttle.core.ThrottleConstants;
    import org.apache.synapse.commons.throttle.core.ThrottleDataHolder;
    import org.apache.synapse.commons.throttle.core.ThrottleConfiguration;
    import org.apache.synapse.commons.throttle.core.ThrottleException;
    import org.apache.synapse.commons.throttle.core.ThrottleContext;
    import org.apache.synapse.commons.throttle.core.AccessInformation;
    import org.apache.synapse.commons.throttle.core.ThrottleFactory;

    import java.util.Map;

    /**
     * The Mediator for the throttling - Throttling will occur according to the ws-policy
     * which is specified as the key for lookup from the registry or the inline policy
     * Throttling can be applied on IP or Domain of the remote caller.Now has support for either
     * Distributed or Standalone throttling schemes. Support two modes of throttling Concurrency and
     * Access rate based throttling In concurrency based throttling - throttling ignores remote callers
     * IP or Domains Considers only concurrent message flows at a given time. Access rate based
     * throttling is bound to a particular remote caller.
     */

    public class ThrottleMediator extends AbstractMediator implements ManagedLifecycle,
            FlowContinuableMediator, EnclosedInlinedSequence {

        /* The key for getting the throttling policy - key refers to a/an [registry] entry */
        private String policyKey = null;
        /* InLine policy object - XML  */
        private OMElement inLinePolicy = null;
        /* The reference to the sequence which will execute when access is denied   */
        private String onRejectSeqKey = null;
        /* The in-line sequence which will execute when access is denied */
        private Mediator onRejectMediator = null;
        /* The reference to the sequence which will execute when access is allowed  */
        private String onAcceptSeqKey = null;
        /* The in-line sequence which will execute when access is allowed */
        private Mediator onAcceptMediator = null;
        /* The concurrent access control group id */
        private String id;
        /* Access rate controller - limit the remote caller access*/
        private AccessRateController accessControler;
        /* ConcurrentAccessController - limit the remote callers concurrent access */
        private ConcurrentAccessController concurrentAccessController = null;
        /* Replicates the concurrent access of remote across the cluster */
        private ConcurrentAccessReplicator concurrentAccessReplicator;
        /* Configuration where Throttle data is being kept */
        private ConfigurationContext configContext;
        /*Throttle Data is kept inside this holder eg :- Caller contexts */
        private ThrottleDataHolder dataHolder;
        /* The property key that used when the ConcurrentAccessController
        look up from ThrottleDataHolder */
        private String key;
        /* Is this env. support clustering*/
        private boolean isClusteringEnable = false;
        /* The Throttle object - holds all runtime and configuration data */
        private Throttle throttle;
        /* Lock used to ensure thread-safe creation of the throttle
        when throttle is created dynamically */
        private final Object throttleLock = new Object();
        /* Last version of dynamic policy resource*/
        private long version;
        private static final String SYMBOL_UNDERSCORE = "_";

        public ThrottleMediator() {
        }

        public boolean mediate(MessageContext synCtx) {

            if (synCtx.getEnvironment().isDebuggerEnabled()) {
                if (super.divertMediationRoute(synCtx)) {
                    return true;
                }
            }

            SynapseLog synLog = getLog(synCtx);
            boolean isResponse = synCtx.isResponse();
            boolean canAccess = true;
            if (!isResponse) {
                if (synLog.isTraceOrDebugEnabled()) {
                    synLog.traceOrDebug("Start : Throttle mediator");
                    if (synLog.isTraceTraceEnabled()) {
                        synLog.traceTrace("Message : " + synCtx.getEnvelope());
                    }
                }
                //we consider dynamic loading of policy loading only for the request flow mediation
                //we ignore policy initialization for the response flow case we use the existing policy
                //reference throttling only applies for request flow mediation
                doInitializeThrottleDynamicPolicy(synCtx, synLog);

                //throttle by concurrency is given the highest priority, if another throttling
                // scheme fails eg :- rate based from this point onward Eg:- access rate
                // checks we need to rollback the previous
                if (concurrentAccessController != null) {
                    canAccess = doThrottleByConcurrency(isResponse, synLog);
                }

                //if the access is success through concurrency throttle and if this is a request message
                //then do access rate based throttling
                if (throttle != null && !isResponse && canAccess) {
                    org.apache.axis2.context.MessageContext axisMC =
                            ((Axis2MessageContext) synCtx).getAxis2MessageContext();
                    canAccess = doThrottleByAccessRate(synCtx, axisMC, configContext, synLog);
                }

                if (concurrentAccessController != null) {
                    //maintain properties in message context for the concurrency throttling
                    synCtx.setProperty(SynapseConstants.SYNAPSE_CONCURRENCY_THROTTLE, true);
                    //maintain properties in message context for the concurrency throttling
                    synCtx.setProperty(SynapseConstants.SYNAPSE_CONCURRENCY_THROTTLE_KEY, key);
                    //maintain properties in message context for the concurrency throttling
                    synCtx.setProperty(SynapseConstants.SYNAPSE_CONCURRENT_ACCESS_CONTROLLER,
                            concurrentAccessController);
                }
                //maintain properties in message context for the concurrency throttling
                if (isClusteringEnable) {
                    synCtx.setProperty(SynapseConstants.SYNAPSE_CONCURRENT_ACCESS_REPLICATOR,
                            concurrentAccessReplicator);
                }
                //depending on the subsequent throttling controller outcome from this point
                // onwards mediation flow branches to either accept sequence or reject sequence
                if (canAccess) {
                    // all the replication functionality of the access rate and concurrency based
                    // throttling handles by itself at throttle core level but for the the concurrency case
                    // this is done explicitly forcing as we make concurrent global state change available
                    // to other cluster nodes as synchronous manner
                    if (isClusteringEnable && concurrentAccessController != null) {
                        if (synLog.isTraceOrDebugEnabled()) {
                            synLog.traceOrDebug("Going to replicates the  " +
                                    "states of the ConcurrentAccessController with key : " + key);
                        }
                        concurrentAccessReplicator.replicate(key, false);
                    }
                    //accept case
                    // property is set to identify whether a request is accepted or rejected looking at
                    // the throttling controller outcome.
                    synCtx.setProperty(SynapseConstants.SYNAPSE_IS_CONCURRENT_ACCESS_ALLOWED, true);
                    if (onAcceptSeqKey != null) {
                        Mediator mediator = synCtx.getSequence(onAcceptSeqKey);
                        if (mediator != null) {
                            ContinuationStackManager.updateSeqContinuationState(synCtx,
                                    getMediatorPosition());
                            return mediator.mediate(synCtx);
                        } else {
                            handleException("Unable to find onAccept sequence with key : "
                                    + onAcceptSeqKey, synCtx);
                        }
                    } else if (onAcceptMediator != null) {
                        ContinuationStackManager.addReliantContinuationState(synCtx, 0,
                                getMediatorPosition());
                        boolean result = onAcceptMediator.mediate(synCtx);
                        if (result) {
                            ContinuationStackManager.removeReliantContinuationState(synCtx);
                        }
                        return result;
                    } else {
                        return true;
                    }

                } else {
                    //reject case
                    // property is set to identify whether a request is accepted or rejected looking at
                    // the throttling controller outcome.
                    synCtx.setProperty(SynapseConstants.SYNAPSE_IS_CONCURRENT_ACCESS_ALLOWED, false);
                    if (onRejectSeqKey != null) {
                        Mediator mediator = synCtx.getSequence(onRejectSeqKey);
                        if (mediator != null) {
                            ContinuationStackManager.updateSeqContinuationState(synCtx,
                                    getMediatorPosition());
                            return mediator.mediate(synCtx);
                        } else {
                            handleException("Unable to find onReject sequence with key : "
                                    + onRejectSeqKey, synCtx);
                        }
                    } else if (onRejectMediator != null) {
                        ContinuationStackManager.addReliantContinuationState(synCtx, 1,
                                getMediatorPosition());
                        boolean result = onRejectMediator.mediate(synCtx);
                        if (result) {
                            ContinuationStackManager.removeReliantContinuationState(synCtx);
                        }
                        return result;
                    } else {
                        return false;
                    }
                }
            }

            synLog.traceOrDebug("End : Throttle mediator");
            return canAccess;
        }

        public boolean mediate(MessageContext synCtx, ContinuationState continuationState) {
            SynapseLog synLog = getLog(synCtx);

            if (synLog.isTraceOrDebugEnabled()) {
                synLog.traceOrDebug("Throttle mediator : Mediating from ContinuationState");
            }

            boolean result;
            boolean isStatisticsEnabled = RuntimeStatisticCollector.isStatisticsEnabled();
            int subBranch = ((ReliantContinuationState) continuationState).getSubBranch();
            if (subBranch == 0) {
                if (!continuationState.hasChild()) {
                    result = ((SequenceMediator) onAcceptMediator).
                            mediate(synCtx, continuationState.getPosition() + 1);
                } else {
                    FlowContinuableMediator mediator =
                            (FlowContinuableMediator) ((SequenceMediator) onAcceptMediator).
                                    getChild(continuationState.getPosition());

                    result = mediator.mediate(synCtx, continuationState.getChildContState());

                    if (isStatisticsEnabled) {
                        ((Mediator) mediator).reportCloseStatistics(synCtx, null);
                    }
                }
                if (isStatisticsEnabled) {
                    onAcceptMediator.reportCloseStatistics(synCtx, null);
                }
            } else {
                if (!continuationState.hasChild()) {
                    result = ((SequenceMediator) onRejectMediator).
                            mediate(synCtx, continuationState.getPosition() + 1);
                } else {
                    FlowContinuableMediator mediator =
                            (FlowContinuableMediator) ((SequenceMediator) onRejectMediator).getChild(
                                    continuationState.getPosition());

                    result = mediator.mediate(synCtx, continuationState.getChildContState());

                    if (isStatisticsEnabled) {
                        ((Mediator) mediator).reportCloseStatistics(synCtx, null);
                    }
                }
                if (isStatisticsEnabled) {
                    onRejectMediator.reportCloseStatistics(synCtx, null);
                }
            }

            return result;
        }

        /**
         * Helper method that handles the concurrent access through throttle
         *
         * @param isResponse Current Message is response or not
         * @param synLog     the Synapse log to use
         * @return true if the caller can access ,o.w. false
         */
        private boolean doThrottleByConcurrency(boolean isResponse, SynapseLog synLog) {
            boolean canAccess = true;
            if (concurrentAccessController != null) {
                // do the concurrency throttling
                int concurrentLimit = concurrentAccessController.getLimit();
                if (synLog.isTraceOrDebugEnabled()) {
                    synLog.traceOrDebug("Concurrent access controller for ID : " + id +
                            " allows : " + concurrentLimit + " concurrent accesses");
                }
                int available;
                if (!isResponse) {
                    available = concurrentAccessController.getAndDecrement();
                    canAccess = available > 0;
                    if (synLog.isTraceOrDebugEnabled()) {
                        synLog.traceOrDebug("Concurrency Throttle : Access " +
                                (canAccess ? "allowed" : "denied") + " :: " + available
                                + " of available of " + concurrentLimit + " connections");
                    }
                }
            }
            return canAccess;
        }

        /**
         * Helper method that handles the access-rate based throttling
         *
         * @param synCtx MessageContext(Synapse)
         * @param axisMC MessageContext(Axis2)
         * @param cc     ConfigurationContext
         * @param synLog the Synapse log to use
         * @return ue if the caller can access ,o.w. false
         */
        private boolean doThrottleByAccessRate(MessageContext synCtx,
                                               org.apache.axis2.context.MessageContext axisMC,
                                               ConfigurationContext cc,
                                               SynapseLog synLog) {

            String callerId = null;
            boolean canAccess = true;
            //domain name of the caller
            String domainName = (String) axisMC.getPropertyNonReplicable(NhttpConstants.REMOTE_HOST);
            Map headers = (Map) axisMC.getProperty(org.apache.axis2.context.MessageContext.TRANSPORT_HEADERS);

            if (headers != null) {
                String xForwardHost = (String) headers.get(NhttpConstants.HEADER_X_FORWARDED_HOST);
                domainName = (xForwardHost != null) ? xForwardHost : domainName;
            }

            // Get Remote IP
            String remoteIP = getIp(headers, axisMC);

            // Using a unique key to identify each api, proxy and inbound endpoint
            String uniqueKey;
            Object artifactName = synCtx.getProperty(SynapseConstants.ARTIFACT_NAME);
            if (artifactName != null && !artifactName.toString().isEmpty()) {
                uniqueKey = id + synCtx.getProperty(SynapseConstants.ARTIFACT_NAME);
            } else {
                uniqueKey = id;
            }
            uniqueKey = uniqueKey.concat(SYMBOL_UNDERSCORE);

            //Using remote caller domain name , If there is a throttle configuration for
            // this domain name ,then throttling will occur according to that configuration
            if (domainName != null) {
                // do the domain based throttling
                if (synLog.isTraceOrDebugEnabled()) {
                    synLog.traceOrDebug("The Domain Name of the caller is :" + domainName);
                }
                // loads the DomainBasedThrottleContext
                ThrottleContext context
                        = throttle.getThrottleContext(ThrottleConstants.DOMAIN_BASED_THROTTLE_KEY);
                if (context != null) {
                    //loads the DomainBasedThrottleConfiguration
                    ThrottleConfiguration config = context.getThrottleConfiguration();
                    if (config != null) {
                        //checks the availability of a policy configuration for  this domain name
                        callerId = config.getConfigurationKeyOfCaller(domainName);
                        if (callerId != null) {  // there is configuration for this domain name
                            //If this is a clustered env.
                            if (isClusteringEnable) {
                                context.setConfigurationContext(cc);
                                context.setThrottleId(uniqueKey + callerId);
                            }

                            try {
                                //Checks for access state
                                AccessInformation accessInformation = accessControler.canAccess(context,
                                        uniqueKey + callerId, ThrottleConstants.DOMAIN_BASE);
                                canAccess = accessInformation.isAccessAllowed();

                                if (synLog.isTraceOrDebugEnabled()) {
                                    synLog.traceOrDebug("Access " + (canAccess ? "allowed" : "denied")
                                            + " for Domain Name : " + domainName);
                                }

                                //In the case of both of concurrency throttling and
                                //rate based throttling have enabled ,
                                //if the access rate less than maximum concurrent access ,
                                //then it is possible to occur death situation.To avoid that reset,
                                //if the access has denied by rate based throttling
                                if (!canAccess && concurrentAccessController != null) {
                                    concurrentAccessController.incrementAndGet();
                                    if (isClusteringEnable) {
                                        dataHolder.setConcurrentAccessController
                                                (key, concurrentAccessController);
                                    }
                                }
                            } catch (ThrottleException e) {
                                handleException("Error occurred during throttling", e, synCtx);
                            }
                        }
                    }
                }
            } else {
                synLog.traceOrDebug("The Domain name of the caller cannot be found");
            }

            //At this point , any configuration for the remote caller hasn't found ,
            //therefore trying to find a configuration policy based on remote caller ip
            if (callerId == null) {
                //do the IP-based throttling
                if (remoteIP == null) {
                    if (synLog.isTraceOrDebugEnabled()) {
                        synLog.traceOrDebug("The IP address of the caller cannot be found");
                    }
                    canAccess = true;

                } else {
                    if (synLog.isTraceOrDebugEnabled()) {
                        synLog.traceOrDebug("The IP Address of the caller is :" + remoteIP);
                    }
                    try {
                        // Loads the IPBasedThrottleContext
                        ThrottleContext context =
                                throttle.getThrottleContext(ThrottleConstants.IP_BASED_THROTTLE_KEY);
                        if (context != null) {
                            //Loads the IPBasedThrottleConfiguration
                            ThrottleConfiguration config = context.getThrottleConfiguration();
                            if (config != null) {
                                //Checks the availability of a policy configuration for  this ip
                                callerId = config.getConfigurationKeyOfCaller(remoteIP);
                                if (callerId != null) {   // there is configuration for this ip
                                    //For clustered env.
                                    if (isClusteringEnable) {
                                        context.setConfigurationContext(cc);
                                        context.setThrottleId(uniqueKey + callerId);
                                    }

                                    //Checks access state
                                    AccessInformation accessInformation = accessControler.canAccess(
                                            context,
                                            uniqueKey + callerId,
                                            ThrottleConstants.IP_BASE);

                                    canAccess = accessInformation.isAccessAllowed();
                                    if (synLog.isTraceOrDebugEnabled()) {
                                        synLog.traceOrDebug("Access " +
                                                (canAccess ? "allowed" : "denied")
                                                + " for IP : " + remoteIP);
                                    }
                                    //In the case of both concurrency throttling and
                                    //rate based throttling are enabled,
                                    //if the access rate is less than maximum concurrent access,
                                    //then it is possible that occur death situation. To avoid that reset,
                                    //if the access has denied by rate based throttling
                                    if (!canAccess && concurrentAccessController != null) {
                                        concurrentAccessController.incrementAndGet();
                                        if (isClusteringEnable) {
                                            dataHolder.setConcurrentAccessController
                                                    (key, concurrentAccessController);
                                        }
                                    }
                                }
                            }
                        }
                    } catch (ThrottleException e) {
                        handleException("Error occurred during throttling", e, synCtx);
                    }
                }
            }
            return canAccess;
        }

        /**
         * Helper method that handles dynamic policy initialization
         *
         * @param synCtx MessageContext(Synapse)
         */
        private void doInitializeThrottleDynamicPolicy(MessageContext synCtx, SynapseLog synLog) {

            if (policyKey == null) {
                return;
            }

            if (synLog.isTraceOrDebugEnabled()) {
                synLog.traceOrDebug("Throttle mediator : Initializing dynamic Policy");
            }

            // If the policy has specified as a registry key.
            // load or re-load policy from registry or local entry if not already available

            Entry entry = synCtx.getConfiguration().getEntryDefinition(policyKey);
            if (entry == null) {
                handleException("Cannot find throttling policy using key : "
                        + policyKey, synCtx);

            } else {

                boolean reCreate = false;
                // if the key refers to a dynamic resource
                if (entry.isDynamic()) {
                    if ((!entry.isCached() || entry.isExpired()) && version != entry.getVersion()) {
                        reCreate = true;
                        version = entry.getVersion();
                    }
                }
                //we ignore the static initialization case
                if (reCreate || throttle == null) {
                    Object entryValue = synCtx.getEntry(policyKey);
                    if (entryValue == null) {
                        handleException(
                                "Null throttling policy returned by Entry : "
                                        + policyKey, synCtx);

                    } else {
                        if (!(entryValue instanceof OMElement)) {
                            handleException("Policy returned from key : " + policyKey +
                                    " is not an OMElement", synCtx);

                        } else {
                            //Check for reload in a cluster environment
                            // For clustered environment ,if the concurrent access controller
                            // is not null and throttle is not null , then must reload.
                            if (isClusteringEnable && concurrentAccessController != null
                                    && throttle != null) {
                                concurrentAccessController = null; // set null ,
                                // because need to reload when throttle gets created again
                            }

                            try {
                                // creation of throttle should be thread safe if multiple request flow
                                // try to create a throttle object
                                synchronized (throttleLock) {
                                    // Creates the throttle from the policy
                                    if (throttle == null) {
                                        throttle = ThrottleFactory.createMediatorThrottle(
                                            PolicyEngine.getPolicy((OMElement) entryValue));
                                    }

                                    //For non-clustered  environment , must re-initiates
                                    //For  clustered  environment,
                                    //concurrent access controller is null ,
                                    //then must re-initiates
                                    if (throttle != null && (concurrentAccessController == null
                                            || !isClusteringEnable)) {
                                        concurrentAccessController =
                                                throttle.getConcurrentAccessController();
                                        if (concurrentAccessController != null) {
                                            dataHolder.setConcurrentAccessController
                                                    (key, concurrentAccessController);
                                        }
                                    }
                                }
                            } catch (ThrottleException e) {
                                handleException("Error processing the throttling policy",
                                        e, synCtx);
                            }
                        }
                    }
                }
            }

        }

        public void init(SynapseEnvironment se) {

            if (onAcceptMediator instanceof ManagedLifecycle) {
                ((ManagedLifecycle) onAcceptMediator).init(se);
            } else if (onAcceptSeqKey != null) {
                SequenceMediator onAcceptSeq =
                        (SequenceMediator) se.getSynapseConfiguration().
                                getSequence(onAcceptSeqKey);

                if (onAcceptSeq == null || onAcceptSeq.isDynamic()) {
                    se.addUnavailableArtifactRef(onAcceptSeqKey);
                }
            }

            if (onRejectMediator instanceof ManagedLifecycle) {
                ((ManagedLifecycle) onRejectMediator).init(se);
            } else if (onRejectSeqKey != null) {
                SequenceMediator onRejectSeq =
                        (SequenceMediator) se.getSynapseConfiguration().
                                getSequence(onRejectSeqKey);

                if (onRejectSeq == null || onRejectSeq.isDynamic()) {
                    se.addUnavailableArtifactRef(onRejectSeqKey);
                }
            }
            //reference to axis2 configuration context
            configContext = ((Axis2SynapseEnvironment) se).getAxis2ConfigurationContext();
            //throttling data holder initialization of
            // runtime throttle data eg :- throttle contexts
            dataHolder = (ThrottleDataHolder) configContext.
                    getProperty(ThrottleConstants.THROTTLE_INFO_KEY);
            if (dataHolder == null) {
                log.debug("Data holder not present in current Configuration Context");
                synchronized (configContext) {
                    dataHolder = (ThrottleDataHolder) configContext.
                            getProperty(ThrottleConstants.THROTTLE_INFO_KEY);
                    if (dataHolder == null) {
                        dataHolder = new ThrottleDataHolder();
                        configContext.setNonReplicableProperty
                                (ThrottleConstants.THROTTLE_INFO_KEY, dataHolder);
                    }
                }
            }
            //initializes whether clustering is enabled an Env. level
            ClusteringAgent clusteringAgent = configContext.getAxisConfiguration().getClusteringAgent();
            if (clusteringAgent != null) {
                isClusteringEnable = true;
            }
            //static policy initialization
            if (inLinePolicy != null) {
                log.debug("Initializing using static throttling policy : " + inLinePolicy);
                try {
                    throttle = ThrottleFactory.
                            createMediatorThrottle(PolicyEngine.getPolicy(inLinePolicy));
                    if (throttle != null && concurrentAccessController == null) {
                        concurrentAccessController = throttle.getConcurrentAccessController();
                        if (concurrentAccessController != null) {
                            dataHolder.setConcurrentAccessController(key, concurrentAccessController);
                        }
                    }
                } catch (ThrottleException e) {
                    handleException("Error processing the throttling policy", e, null);
                }
            }
            //access rate controller initialization
            accessControler = new AccessRateController();
            //replicator for global concurrent state maintenance
            if (isClusteringEnable) {
                concurrentAccessReplicator = new ConcurrentAccessReplicator(configContext);
            }

        }

        public void destroy() {
            //if synapse configuration refreshes we need to drop the previous throttle data
            if (configContext != null) {
                dataHolder.removeConcurrentAccessController(key);
            }
            if (onAcceptMediator instanceof ManagedLifecycle) {
                ((ManagedLifecycle) onAcceptMediator).destroy();
            }
            if (onRejectMediator instanceof ManagedLifecycle) {
                ((ManagedLifecycle) onRejectMediator).destroy();
            }
        }

        /**
         * To get the policy key - The key for which will used to lookup policy from the registry
         *
         * @return String
         */
        public String getPolicyKey() {
            return policyKey;
        }

        /**
         * To set the policy key - The key for which lookup from the registry
         *
         * @param policyKey Value for picking policy from the registry
         */
        public void setPolicyKey(String policyKey) {
            this.policyKey = policyKey;
        }

        /**
         * getting throttle policy which has defined as InLineXML
         *
         * @return InLine Throttle Policy
         */
        public OMElement getInLinePolicy() {
            return inLinePolicy;
        }

        /**
         * setting throttle policy which has defined as InLineXML
         *
         * @param inLinePolicy Inline policy
         */
        public void setInLinePolicy(OMElement inLinePolicy) {
            this.inLinePolicy = inLinePolicy;
        }

        public String getOnRejectSeqKey() {
            return onRejectSeqKey;
        }

        public void setOnRejectSeqKey(String onRejectSeqKey) {
            this.onRejectSeqKey = onRejectSeqKey;
        }

        public Mediator getOnRejectMediator() {
            return onRejectMediator;
        }

        public void setOnRejectMediator(Mediator onRejectMediator) {
            this.onRejectMediator = onRejectMediator;
        }

        public String getOnAcceptSeqKey() {
            return onAcceptSeqKey;
        }

        public void setOnAcceptSeqKey(String onAcceptSeqKey) {
            this.onAcceptSeqKey = onAcceptSeqKey;
        }

        public Mediator getOnAcceptMediator() {
            return onAcceptMediator;
        }

        public void setOnAcceptMediator(Mediator onAcceptMediator) {
            this.onAcceptMediator = onAcceptMediator;
        }

        public String getId() {
            return id;
        }

        public void setId(String id) {
            this.id = id;
            this.key = ThrottleConstants.THROTTLE_PROPERTY_PREFIX + id + ThrottleConstants.CAC_SUFFIX;
        }

        @Override
        public boolean isContentAware() {
            return false;
        }

        @Override
        public Mediator getInlineSequence(SynapseConfiguration synCfg, int inlinedSeqIdentifier) {
            if (inlinedSeqIdentifier == 0) {
                if (onRejectMediator != null) {
                    return onRejectMediator;
                } else if (onRejectSeqKey != null) {
                    return synCfg.getSequence(onRejectSeqKey);
                }
            } else if (inlinedSeqIdentifier == 1) {
                if (onAcceptMediator != null) {
                    return onAcceptMediator;
                } else if (onAcceptSeqKey != null) {
                    return synCfg.getSequence(onAcceptSeqKey);
                }
            }
            return null;
        }

        @Override
        public void setComponentStatisticsId(ArtifactHolder holder) {
            if (getAspectConfiguration() == null) {
                configure(new AspectConfiguration(getMediatorName()));
            }
            String mediatorId =
                    StatisticIdentityGenerator.getIdForFlowContinuableMediator(getMediatorName(), ComponentType.MEDIATOR, holder);
            getAspectConfiguration().setUniqueId(mediatorId);

            String childId;
            if (onAcceptSeqKey != null) {
                childId = StatisticIdentityGenerator.getIdReferencingComponent(onAcceptSeqKey, ComponentType.SEQUENCE, holder);
                StatisticIdentityGenerator.reportingEndEvent(childId, ComponentType.SEQUENCE, holder);
            } else if (onAcceptMediator != null) {
                onAcceptMediator.setComponentStatisticsId(holder);
            }
            if (onRejectSeqKey != null) {
                childId = StatisticIdentityGenerator.getIdReferencingComponent(onRejectSeqKey, ComponentType.SEQUENCE, holder);
                StatisticIdentityGenerator.reportingEndEvent(childId, ComponentType.SEQUENCE, holder);
            } else if (onRejectMediator != null) {
                onRejectMediator.setComponentStatisticsId(holder);
            }
            StatisticIdentityGenerator.reportingFlowContinuableEndEvent(mediatorId, ComponentType.MEDIATOR, holder);
        }

        /**
         * Extracts the remote IP from Message Context.
         *
         * @param transportHeaderMap    Message context
         * @param axisMC                org.apache.axis2.context.MessageContext - Axis2 Message Context.
         * @return IP as a String.
         */
        public static String getIp(Map<String, String> transportHeaderMap, org.apache.axis2.context.MessageContext axisMC) {

            String remoteIP = "";
            // Check whether headers map is null and x forwarded for header is present.
            if (transportHeaderMap != null) {
                remoteIP = transportHeaderMap.get(NhttpConstants.HEADER_X_FORWARDED_FOR);
            }

            //Setting IP of the client by looking at x forded for header and  if it's empty get remote address.
            if (remoteIP != null && !remoteIP.isEmpty()) {
                if (remoteIP.indexOf(",") > 0) {
                    remoteIP = remoteIP.substring(0, remoteIP.indexOf(","));
                }
            } else {
                remoteIP = (String) axisMC.getPropertyNonReplicable(org.apache.axis2.context.MessageContext.REMOTE_ADDR);
            }

            return remoteIP;
        }
    }