# CallerContext.java

    /*
    *  Copyright (c) 2005-2010, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
    *
    * Licensed 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.commons.throttle.core;

    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;

    import java.io.Serializable;
    import java.util.UUID;
    import java.util.concurrent.atomic.AtomicLong;

    /**
     * Contains all runtime data for a particular remote caller.
     * provides the default rate based access controller algorithm implementation.
     * This is not thread-safe
     */

    public abstract class CallerContext implements Serializable, Cloneable {
        private static final long serialVersionUID = 1652165180220263492L;
        private static Log log = LogFactory.getLog(CallerContext.class.getName());

        /* next access time - the end of prohibition */
        private long nextAccessTime = 0;
        /* first access time - when caller came across the on first time */
        private long firstAccessTime = 0;
        /* The nextTimeWindow - beginning of next unit time period- end of current unit time period  */
        private long nextTimeWindow = 0;
        /* The globalCount to keep track number of request */
        private AtomicLong globalCount = new AtomicLong(0);

        private String roleId;
        private long unitTime;
        /**
         * Count to keep track of local (specific to this node) number of requests
         */
        private AtomicLong localCount = new AtomicLong(0);

        /**
         * Used for debugging purposes. *
         */
        private UUID uuid = UUID.randomUUID();

        /* The Id of caller */
        private String id;

        public CallerContext clone() throws CloneNotSupportedException {
            super.clone();
            CallerContext clone = new CallerContext(this.id) {
                @Override
                public int getType() {
                    return CallerContext.this.getType();
                }
            };
            clone.nextAccessTime = this.nextAccessTime;
            clone.firstAccessTime = this.firstAccessTime;
            clone.nextTimeWindow = this.nextTimeWindow;
            clone.globalCount = new AtomicLong(this.globalCount.longValue());
            clone.localCount = new AtomicLong(this.localCount.longValue());

            clone.roleId = this.roleId;
            localCount.set(0);
            return clone;
        }

        public CallerContext(String ID) {
            if (ID == null || "".equals(ID)) {
                throw new InstantiationError("Couldn't create a CallContext for an empty " +
                                             "remote caller ID");
            }
            this.id = ID.trim();
        }

        public UUID getUuid() {
            return uuid;
        }

        /**
         * @return Returns Id of caller
         */
        public String getId() {
            return this.id;
        }

        /**
         * Init the access for a particular caller , caller will registered with context
         *
         * @param configuration   -The Configuration for this caller
         * @param throttleContext -The Throttle Context
         * @param currentTime     -The system current time in milliseconds
         */
        private void initAccess(CallerConfiguration configuration, ThrottleContext throttleContext, long currentTime) {
            this.unitTime = configuration.getUnitTime();
            this.firstAccessTime = currentTime;
            this.nextTimeWindow = this.firstAccessTime + this.unitTime;
            this.roleId = configuration.getID();
            //Also we need to pick counter value associated with time window.
            throttleContext.addCallerContext(this, this.id);
            throttleContext.replicateTimeWindow(this.id);
        }

        /**
         * To verify access if the unit time has already not over
         *
         * @param configuration   -  The Configuration for this caller
         * @param throttleContext -The Throttle Context
         * @param currentTime     -The system current time
         * @return boolean        -The boolean value which say access will allow or not
         */
        private boolean canAccessIfUnitTimeNotOver(CallerConfiguration configuration,
                                                   ThrottleContext throttleContext, long currentTime) {
            boolean canAccess = false;
            int maxRequest = configuration.getMaximumRequestPerUnitTime();
            if (maxRequest != 0) {
                if ((this.globalCount.get() + this.localCount.get()) < maxRequest) {    //If the globalCount is less than max request
                    if (log.isDebugEnabled()) {
                        log.debug("CallerContext Checking access if unit time is not over and less than max count>> Access "
                                + "allowed=" + maxRequest + " available="+ (maxRequest - (this.globalCount.get() + this.localCount.get()))
                                +" key=" + this.getId() + " currentGlobalCount=" + globalCount + " currentTime="
                                +  currentTime + " " + "nextTimeWindow=" + this.nextTimeWindow + " currentLocalCount=" + localCount + " Tier="
                                + configuration.getID() + " nextAccessTime=" + this.nextAccessTime);
                    }
                    canAccess = true;     // can continue access
                    this.localCount.incrementAndGet();
                    // Send the current state to others (clustered env)
                    throttleContext.flushCallerContext(this, id);
                    // can complete access

                } else {
                    //else , if caller has not already prohibit
                    if (this.nextAccessTime == 0) {
                        //and if there is no prohibit time  period in configuration
                        long prohibitTime = configuration.getProhibitTimePeriod();
                        if (prohibitTime == 0) {
                            //prohibit access until unit time period is over
                            this.nextAccessTime = this.firstAccessTime + configuration.getUnitTime();
                        } else {
                            //if there is a prohibit time period in configuration ,then
                            //set it as prohibit period
                            this.nextAccessTime = currentTime + prohibitTime;
                        }
                        if (log.isDebugEnabled()) {
                            String type = ThrottleConstants.IP_BASE == configuration.getType() ?
                                    "IP address" : "domain";
                            log.debug("Maximum Number of requests are reached for caller with "
                                    + type + " - " + this.id);
                        }
                        // Send the current state to others (clustered env)
                        throttleContext.flushCallerContext(this, id);
                    } else {
                        // else , if the caller has already prohibit and prohibit
                        // time period has already over
                        if (this.nextAccessTime <= currentTime) {
                            if (log.isDebugEnabled()) {
                                log.debug("CallerContext Checking access if unit time is not over before time window exceed >> "
                                        + "Access allowed=" + maxRequest + " available="
                                        +  (maxRequest - (this.globalCount.get() + this.localCount.get()))
                                        + " key=" + this.getId() + " currentGlobalCount=" + globalCount
                                        + " currentTime=" + currentTime + " " + "nextTimeWindow=" + this.nextTimeWindow
                                        + " currentLocalCount=" + localCount + " " + "Tier=" + configuration.getID()
                                        + " nextAccessTime=" + this.nextAccessTime);
                            }
                            // remove previous caller context
                            if (this.nextTimeWindow != 0) {
                                throttleContext.removeCallerContext(id);
                            }
                            // reset the states so that, this is the first access
                            this.nextAccessTime = 0;
                            canAccess = true;

                            this.globalCount.set(0);// can access the system   and this is same as first access
                            this.localCount.set(1);
                            this.firstAccessTime = currentTime;
                            this.nextTimeWindow = currentTime + configuration.getUnitTime();
                            throttleContext.replicateTimeWindow(this.id);
                            throttleContext.addAndFlushCallerContext(this, this.id);

                            if(log.isDebugEnabled()) {
                                log.debug("Caller=" + this.getId() + " has reset counters and added for replication when unit "
                                          + "time is not over");
                            }
                        } else {
                            if (log.isDebugEnabled()) {
                                String type = ThrottleConstants.IP_BASE == configuration.getType() ?
                                        "IP address" : "domain";
                                log.debug("Prohibit period is not yet over for caller with "
                                        + type + " - " + this.id);
                            }
                        }
                    }
                }

            }
            return canAccess;
        }

        /**
         * To verify access if unit time has already over
         *
         * @param configuration   -The Configuration for this caller
         * @param throttleContext -The Throttle that caller having pass
         * @param currentTime     -The system current time
         * @return boolean        -The boolean value which say access will allow or not
         */
        private boolean canAccessIfUnitTimeOver(CallerConfiguration configuration, ThrottleContext throttleContext, long currentTime) {

            boolean canAccess = false;
            // if number of access for a unit time is less than MAX and
            // if the unit time period (session time) has just over
            int maxRequest = configuration.getMaximumRequestPerUnitTime();
            if (maxRequest != 0) {
                if ((this.globalCount.get() + this.localCount.get()) < maxRequest) {
                    if (this.nextTimeWindow != 0) {
                        // Removes and sends the current state to others  (clustered env)
                        //remove previous callercontext instance
                        throttleContext.removeCallerContext(id);
                        this.globalCount.set(0);// can access the system   and this is same as first access
                        this.localCount.set(1);
                        this.firstAccessTime = currentTime;
                        this.nextTimeWindow = currentTime + configuration.getUnitTime();
                        throttleContext.replicateTimeWindow(this.id);
                        // registers caller and send the current state to others (clustered env)
                        throttleContext.addAndFlushCallerContext(this, id);
                    }
                    if (log.isDebugEnabled()) {
                        log.debug("CallerContext Checking access if unit time over next time window>> Access allowed="
                                +  maxRequest + " available=" + (maxRequest - (this.globalCount.get() + this.localCount.get()))
                                + " key=" + this.getId()+ " currentGlobalCount=" + globalCount + " currentTime=" + currentTime
                                + " nextTimeWindow=" + this.nextTimeWindow +" currentLocalCount=" + localCount + " Tier="
                                + configuration.getID() + " nextAccessTime="+ this.nextAccessTime);
                    }
                    canAccess = true; // this is bonus access
                    //next time callers can access as a new one
                } else {
                    // if number of access for a unit time has just been greater than MAX now same as a new session
                    // OR if caller in prohibit session  and prohibit period has just over
                    if ((this.nextAccessTime == 0) || (this.nextAccessTime <= currentTime)) {
                        if (log.isDebugEnabled()) {
                            log.debug("CallerContext Checking access if unit time over>> Access allowed=" + maxRequest
                                    + " available=" + (maxRequest - (this.globalCount.get() + this.localCount.get())) + " key=" + this.getId()
                                    + " currentGlobalCount=" + globalCount + " currentTime=" + currentTime + " nextTimeWindow=" + this.nextTimeWindow
                                    + " currentLocalCount=" + localCount + " Tier=" + configuration.getID() + " nextAccessTime="
                                    + this.nextAccessTime);
                        }
                        //remove previous callercontext instance
                        if (this.nextTimeWindow != 0) {
                            throttleContext.removeCallerContext(id);
                        }
                        // reset the states so that, this is the first access
                        this.nextAccessTime = 0;
                        canAccess = true;

                        this.globalCount.set(0);// can access the system   and this is same as first access
                        this.localCount.set(1);
                        this.firstAccessTime = currentTime;
                        this.nextTimeWindow = currentTime + configuration.getUnitTime();
                        // registers caller and send the current state to others (clustered env)
                        throttleContext.replicateTimeWindow(this.id);
                        throttleContext.addAndFlushCallerContext(this, id);

                        if(log.isDebugEnabled()) {
                            log.debug("Caller=" + this.getId() + " has reset counters and added for replication when unit "
                                      + "time is over");
                        }
                    } else {
                        // if  caller in prohibit session  and prohibit period has not  over
                        if (log.isDebugEnabled()) {
                            String type = ThrottleConstants.IP_BASE == configuration.getType() ?
                                    "IP address" : "domain";
                            log.debug("Even unit time has over , CallerContext in prohibit state :"
                                    + type + " - " + this.id);
                        }
                    }
                }

            }
            return canAccess;

        }

        /**
         * Clean up the callers - remove all callers that have expired their time window
         *
         * @param configuration   -The Configuration for this caller
         * @param throttleContext -The Throttle that caller having pass
         * @param currentTime     -The system current time
         */
        public void cleanUpCallers(CallerConfiguration configuration,
                                   ThrottleContext throttleContext, long currentTime) {

            if (log.isDebugEnabled()) {
                log.debug("Cleaning up the inactive caller's states ... ");
            }
            if (configuration == null) {
                if (log.isDebugEnabled()) {
                    log.debug("Couldn't find the configuration .");
                }
                return;
            }
            // if number of access for a unit time is less than MAX and
            // if the unit time period (session time) has over

            int maxRequest = configuration.getMaximumRequestPerUnitTime();
            if (!(maxRequest == 0)) {
                if ((this.globalCount.get() + this.localCount.get()) <= (maxRequest - 1)) {
                    if (this.nextTimeWindow != 0 && this.nextTimeWindow < (currentTime - this.unitTime)) {
                        if (log.isDebugEnabled()) {
                            log.debug("Removing caller with id " + this.id);
                        }
                        //Removes the previous callercontext and Sends the current state to
                        //  others (clustered env)
                        throttleContext.removeAndDestroyShareParamsOfCaller(id);
                    }
                } else {
                    // if number of access for a unit time has just been greater than MAX
                    // now same as a new session
                    // OR
                    //  if caller in prohibit session  and prohibit period has just over and only
                    if ((this.nextAccessTime == 0) || this.nextAccessTime < (currentTime - this.unitTime)) {
                        if (this.nextTimeWindow != 0 && this.nextTimeWindow < (currentTime - this.unitTime)) {
                            if (log.isDebugEnabled()) {
                                log.debug("Removing caller with id " + this.id);
                            }
                            //Removes the previous callercontext and Sends
                            //  the current state to others (clustered env)
                            throttleContext.removeAndDestroyShareParamsOfCaller(id);
                        }
                    }
                }
            }
        }

        /**
         * Check whether that caller can access or not ,based on current state and pre-defined policy
         *
         * @param throttleContext -The Context for this caller - runtime state
         * @param configuration   -The Configuration for this caller - data from policy
         * @param currentTime     -The current system time
         * @return boolean        -The boolean value which say access will allow or not
         * @throws ThrottleException throws for invalid throttle configuration
         */
        public boolean canAccess(ThrottleContext throttleContext, CallerConfiguration configuration,
                                 long currentTime) throws ThrottleException {
            boolean canAccess;
            if (configuration == null) {
                if (log.isDebugEnabled()) {
                    log.debug("Couldn't find the configuration .");
                }
                return true;
            }
            if (configuration.getMaximumRequestPerUnitTime() < 0
                    || configuration.getUnitTime() <= 0
                    || configuration.getProhibitTimePeriod() < 0) {
                throw new ThrottleException("Invalid Throttle Configuration");
            }

            // if caller access first time in his new session
            if (this.firstAccessTime == 0) {
                initAccess(configuration, throttleContext, currentTime);
            }
            // if unit time period (session time) is not over
            if (this.nextTimeWindow > currentTime) {
                canAccess = canAccessIfUnitTimeNotOver(configuration, throttleContext, currentTime);
            } else {
                canAccess = canAccessIfUnitTimeOver(configuration, throttleContext, currentTime);
            }

            return canAccess;

        }

        /**
         * Returns the next time window
         *
         * @return long value of next time window
         */
        public long getNextTimeWindow() {
            return this.nextTimeWindow;
        }

        public void incrementGlobalCounter(int incrementBy) {
            globalCount.addAndGet(incrementBy);
        }

        public void incrementLocalCounter() {
            localCount.incrementAndGet();
        }

        public long getGlobalCounter() {
            return globalCount.get();
        }

        public void setGlobalCounter(long counter) {
            globalCount.set(counter);
        }

        public void setLocalCounter(long counter) {
            localCount.set(counter);
        }

        public long getLocalCounter() {
            return localCount.get();
        }

        public void resetLocalCounter() {
            localCount.set(0);
        }

        public void resetGlobalCounter() {
            globalCount.set(0);
        }

        /**
         * Gets type of throttle that this caller belong  ex : ip/domain
         *
         * @return Returns the type of the throttle
         */
        public abstract int getType();

        public long getFirstAccessTime() {
            return firstAccessTime;
        }

        public void setFirstAccessTime(long firstAccessTime) {
            this.firstAccessTime = firstAccessTime;
        }

        public void setNextTimeWindow(long nextTimeWindow) {
            this.nextTimeWindow = nextTimeWindow;
        }

        public long getUnitTime() {
            return unitTime;
        }

        public void setUnitTime(long unitTime) {
            this.unitTime = unitTime;
        }

        public String getRoleId() {
            return roleId;
        }

        public void setRoleId(String roleId) {
            this.roleId = roleId;
        }
    }