/*
 * Copyright 2002-2017 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.transaction.support;

import java.util.Date;

import org.springframework.transaction.TransactionTimedOutException;

/**
 * Convenient base class for resource holders.
 *
 * <p>Features rollback-only support for participating transactions.
 * Can expire after a certain number of seconds or milliseconds
 * in order to determine a transactional timeout.
 *
 * @author Juergen Hoeller
 * @since 02.02.2004
 * @see org.springframework.jdbc.datasource.DataSourceTransactionManager#doBegin
 * @see org.springframework.jdbc.datasource.DataSourceUtils#applyTransactionTimeout
 */
public abstract class ResourceHolderSupport implements ResourceHolder {

        private boolean synchronizedWithTransaction = false;

        private boolean rollbackOnly = false;

        private Date deadline;

        private int referenceCount = 0;

        private boolean isVoid = false;


        /**
         * Mark the resource as synchronized with a transaction.
         */
        public void setSynchronizedWithTransaction(boolean synchronizedWithTransaction) {
                this.synchronizedWithTransaction = synchronizedWithTransaction;
        }

        /**
         * Return whether the resource is synchronized with a transaction.
         */
        public boolean isSynchronizedWithTransaction() {
                return this.synchronizedWithTransaction;
        }

        /**
         * Mark the resource transaction as rollback-only.
         */
        public void setRollbackOnly() {
                this.rollbackOnly = true;
        }

        /**
         * Return whether the resource transaction is marked as rollback-only.
         */
        public boolean isRollbackOnly() {
                return this.rollbackOnly;
        }

        /**
         * Set the timeout for this object in seconds.
         * @param seconds number of seconds until expiration
         */
        public void setTimeoutInSeconds(int seconds) {
                setTimeoutInMillis(seconds * 1000L);
        }

        /**
         * Set the timeout for this object in milliseconds.
         * @param millis number of milliseconds until expiration
         */
        public void setTimeoutInMillis(long millis) {
                this.deadline = new Date(System.currentTimeMillis() + millis);
        }

        /**
         * Return whether this object has an associated timeout.
         */
        public boolean hasTimeout() {
                return (this.deadline != null);
        }

        /**
         * Return the expiration deadline of this object.
         * @return the deadline as Date object
         */
        public Date getDeadline() {
                return this.deadline;
        }

        /**
         * Return the time to live for this object in seconds.
         * Rounds up eagerly, e.g. 9.00001 still to 10.
         * @return number of seconds until expiration
         * @throws TransactionTimedOutException if the deadline has already been reached
         */
        public int getTimeToLiveInSeconds() {
                double diff = ((double) getTimeToLiveInMillis()) / 1000;
                int secs = (int) Math.ceil(diff);
                checkTransactionTimeout(secs <= 0);
                return secs;
        }

        /**
         * Return the time to live for this object in milliseconds.
         * @return number of millseconds until expiration
         * @throws TransactionTimedOutException if the deadline has already been reached
         */
        public long getTimeToLiveInMillis() throws TransactionTimedOutException{
                if (this.deadline == null) {
                        throw new IllegalStateException("No timeout specified for this resource holder");
                }
                long timeToLive = this.deadline.getTime() - System.currentTimeMillis();
                checkTransactionTimeout(timeToLive <= 0);
                return timeToLive;
        }

        /**
         * Set the transaction rollback-only if the deadline has been reached,
         * and throw a TransactionTimedOutException.
         */
        private void checkTransactionTimeout(boolean deadlineReached) throws TransactionTimedOutException {
                if (deadlineReached) {
                        setRollbackOnly();
                        throw new TransactionTimedOutException("Transaction timed out: deadline was " + this.deadline);
                }
        }

        /**
         * Increase the reference count by one because the holder has been requested
         * (i.e. someone requested the resource held by it).
         */
        public void requested() {
                this.referenceCount++;
        }

        /**
         * Decrease the reference count by one because the holder has been released
         * (i.e. someone released the resource held by it).
         */
        public void released() {
                this.referenceCount--;
        }

        /**
         * Return whether there are still open references to this holder.
         */
        public boolean isOpen() {
                return (this.referenceCount > 0);
        }

        /**
         * Clear the transactional state of this resource holder.
         */
        public void clear() {
                this.synchronizedWithTransaction = false;
                this.rollbackOnly = false;
                this.deadline = null;
        }

        /**
         * Reset this resource holder - transactional state as well as reference count.
         */
        @Override
        public void reset() {
                clear();
                this.referenceCount = 0;
        }

        @Override
        public void unbound() {
                this.isVoid = true;
        }

        @Override
        public boolean isVoid() {
                return this.isVoid;
        }

}