org.darkware.wpman.agents.CronEvent.java Source code

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Here is the source code for org.darkware.wpman.agents.CronEvent.java

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/*******************************************************************************
 * Copyright (c) 2016. darkware.org and contributors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 ******************************************************************************/

package org.darkware.wpman.agents;

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import com.google.common.base.Objects;
import org.darkware.wpman.actions.WPCronHookExec;
import org.darkware.wpman.data.WPBlog;
import org.darkware.wpman.data.WPCronHook;
import org.darkware.wpman.util.serialization.MinimalBlogSerializer;

import java.time.LocalDateTime;
import java.time.temporal.ChronoUnit;
import java.util.Comparator;

/**
 * A helper class for storing {@link WPCronHook}s and associated objects.
 */
public class CronEvent {
    @JsonSerialize(using = MinimalBlogSerializer.class)
    private final WPBlog blog;
    private final String hook;
    private final LocalDateTime execTime;
    @JsonIgnore
    private WPCronHookExec action;

    /**
     * Creates a new event associating the blog, hook, and execution time.
     *
     * @param blog The {@link WPBlog} the hook executes against.
     * @param hook The name of the hook to execute.
     * @param execTime The requested execution time of the hook.
     */
    public CronEvent(final WPBlog blog, final String hook, final LocalDateTime execTime) {
        super();

        this.blog = blog;
        this.hook = hook;
        this.execTime = execTime.withNano(0);
    }

    /**
     * Creates a new event associating the blog and a {@link WPCronHook} instance.
     *
     * @param blog The {@link WPBlog} the hook executes against.
     * @param cronHook The {@link WPCronHook} encapsulating the hook execution event.
     */
    public CronEvent(final WPBlog blog, final WPCronHook cronHook) {
        this(blog, cronHook.getHook(), cronHook.getNextRun());
    }

    /**
     * Attach a {@code WPCronHookExec} action to this event.
     *
     * @param action The action that executes this event.
     */
    public void attachAction(final WPCronHookExec action) {
        synchronized (this) {
            if (this.action != null)
                throw new IllegalStateException("Attempted to attach an action to an already attached event.");

            this.action = action;
        }
    }

    /**
     * Fetch the {@code WPCronHookExec} action that is registered to execute this event.
     *
     * @return The {@code WPAction} that executes this event.
     */
    public WPCronHookExec getAction() {
        return this.action;
    }

    /**
     * Checks to see if a given {@code CronEvent} is reasonably close to this event. Presumably
     * this would be used to decide if the other event could piggyback onto the same execution action.
     *
     * @param check The {@code CronEvent} to check against.
     * @return {@code true} if the event is from the same blog and is reasonably close to the same
     * execution time, otherwise {@code false}.
     */
    public boolean reasonablyCloseTo(final CronEvent check) {
        // Check the blog
        if (!this.blog.equals(check.blog))
            return false;

        // Check the time
        if (Math.abs((check.execTime.until(this.execTime, ChronoUnit.SECONDS))) > 15)
            return false;

        return true;
    }

    /**
     * Fetch the blog this event is running against.
     *
     * @return The {@link WPBlog} linked to this event.
     */
    public WPBlog getBlog() {
        return this.blog;
    }

    /**
     * Fetch the target execution time for this event. This is not a guaranteed time. The time may be
     * shifted somewhat in order to group it with temporally nearby events or execution might be delayed
     * due to a lack of available threads in the pool.
     *
     * @return The target execution time as a {@link LocalDateTime}.
     */
    public LocalDateTime getExecTime() {
        return this.execTime;
    }

    /**
     * Fetch the identifier of the hook to execute.
     *
     * @return The {@code String} identifier of the hook.
     */
    public String getHook() {
        return this.hook;
    }

    @Override
    public boolean equals(final Object o) {
        if (this == o)
            return true;
        if (!(o instanceof CronEvent))
            return false;
        final CronEvent cronEvent = (CronEvent) o;
        return Objects.equal(this.blog, cronEvent.blog) && Objects.equal(this.hook, cronEvent.hook)
                && Objects.equal(this.execTime, cronEvent.execTime);
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(this.blog, this.hook, this.execTime);
    }

    @Override
    public String toString() {
        return this.hook + "@" + this.execTime;
    }

    /**
     * This is a {@link Comparator} for {@link CronEvent}s which is based solely upon the target execution
     * time.
     */
    public static class ExecTimeComparator implements Comparator<CronEvent> {
        @Override
        public int compare(final CronEvent o1, final CronEvent o2) {
            return o1.getExecTime().compareTo(o2.getExecTime());
        }
    }
}