FixAntenna/NetCore/FixEngine/Scheduler/SessionTaskScheduler.cs

// Copyright (c) 2022 EPAM Systems
//
// 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.

using System;
using System.Collections.Generic;
using System.Linq;
using Epam.FixAntenna.NetCore.Common.Logging;
using Epam.FixAntenna.NetCore.FixEngine.Scheduler.Tasks;
using Quartz;
using Quartz.Impl;
using Quartz.Impl.Matchers;
using Quartz.Simpl;

namespace Epam.FixAntenna.NetCore.FixEngine.Scheduler
{
	internal class SessionTaskScheduler
	{
		private static readonly ILog Log = LogFactory.GetLog(typeof(SessionTaskScheduler));
		private readonly IScheduler _scheduler;
		private readonly SessionParameters _sessionParameters;

		// We want a separate scheduler per session, so we need to use a unique per session scheduler name.
		// SessionId is not good for that as tests can create several sessions with the same Id.
		private readonly string _schedulerName = Guid.NewGuid().ToString();

		internal SessionTaskScheduler(SessionParameters sessionParameters)
		{
			_sessionParameters = sessionParameters;

			DirectSchedulerFactory.Instance.CreateScheduler(_schedulerName, _schedulerName, new DefaultThreadPool(), new RAMJobStore());
			_scheduler = DirectSchedulerFactory.Instance.GetScheduler(_schedulerName).Result;
			_scheduler = _scheduler ?? throw new InvalidOperationException("Cannot create scheduler.");

			_scheduler.Start();
		}

		internal bool IsShutdown() => _scheduler.IsShutdown;

		internal void ScheduleCronTask<T>(string pipedCronExpression, TimeZoneInfo timeZone) where T : AbstractSessionTask
		{
			ScheduleCronJob<T>(pipedCronExpression, timeZone);
		}

		internal void ScheduleHeartbeat(TimeSpan checkHeartbeatInterval)
		{
			var jobKey = CreateJobKey<InactivityCheckTask>();

			DescheduleJob(jobKey);

			var job = CreateJob<InactivityCheckTask>(jobKey);
			
			var trigger = TriggerBuilder.Create()
				.WithSimpleSchedule(s => s
					.WithInterval(checkHeartbeatInterval)
					.WithMisfireHandlingInstructionIgnoreMisfires()
					.RepeatForever())
				.Build();
			
			var nextRun = _scheduler.ScheduleJob(job, trigger).Result;
			Log.Trace($"{nameof(InactivityCheckTask)} will run at {nextRun:O}");
		}

		internal void ScheduleTestRequest(TimeSpan checkTestRequestInterval)
		{
			var jobKey = CreateJobKey<TestRequestTask>();

			DescheduleJob(jobKey);

			var job = CreateJob<TestRequestTask>(jobKey);
			
			var trigger = TriggerBuilder.Create()
				.StartAt(DateTimeOffset.Now.AddSeconds(1))
				.WithSimpleSchedule(s => s
					.WithInterval(checkTestRequestInterval)
					.WithMisfireHandlingInstructionIgnoreMisfires()
					.RepeatForever())
				.Build();
			
			var nextRun = _scheduler.ScheduleJob(job, trigger).Result;
			Log.Trace($"{nameof(TestRequestTask)} will run at {nextRun:O}");
		}

		internal void ScheduleSeqReset(TimeSpan resetTime, TimeZoneInfo resetTimeZone)
		{
			var jobKey = CreateJobKey<ResetSeqNumTask>();

			DescheduleJob(jobKey);

			var job = CreateJob<ResetSeqNumTask>(jobKey);

			var trigger = TriggerBuilder.Create()
				.WithDailyTimeIntervalSchedule(s => s
					.WithIntervalInHours(24)
					.StartingDailyAt(new TimeOfDay(resetTime.Hours, resetTime.Minutes, resetTime.Seconds))
					.InTimeZone(resetTimeZone))
				.Build();

			var nextRun = _scheduler.ScheduleJob(job, trigger).Result;
			Log.Trace($"{nameof(ResetSeqNumTask)} will run at {nextRun:O}");
		}

		internal bool IsTaskScheduled<T>() where T : AbstractSessionTask
		{
			var jobKey = CreateJobKey<T>();
			return JobExists(jobKey);
		}

		internal IEnumerable<string> GetCronExpressionsForScheduledCronTask<T>() where T : AbstractSessionTask
		{
			var jobKey = CreateJobKey<T>();
			if (!JobExists(jobKey)) return Enumerable.Empty<string>();

			var triggers = _scheduler.GetTriggersOfJob(jobKey).Result;
			var result = new List<string>();
			foreach (var trigger in triggers)
			{
				if (trigger is ICronTrigger cronTrigger)
				{
					result.Add(cronTrigger.CronExpressionString);
				}
			}

			return result;
		}

		internal void DescheduleTask<T>() where T : AbstractSessionTask
		{
			var jobKey = CreateJobKey<T>();
			DescheduleJob(jobKey);
		}

		internal void DescheduleAllTasks()
		{
			var jobKeys = _scheduler.GetJobKeys(GroupMatcher<JobKey>.AnyGroup()).Result;
			_scheduler.DeleteJobs(jobKeys).Wait();
		}

		internal void Shutdown()
		{
			_scheduler.Shutdown(false).Wait();
		}

		private JobKey CreateJobKey<T>() where T : IJob
		{
			return new JobKey(typeof(T).Name, _schedulerName);
		}

		private bool JobExists(JobKey jobKey)
		{
			return _scheduler.CheckExists(jobKey).Result;
		}

		private void ScheduleCronJob<T>(string pipedCronExpression, TimeZoneInfo timeZone)
			where T: IJob
		{
			var jobKey = CreateJobKey<T>();

			DescheduleJob(jobKey);

			var job = CreateJob<T>(jobKey);
			var triggers = MultipartCronExpression
				.ExtractCronExpressions(pipedCronExpression)
				.Select(cronExpression => TriggerBuilder.Create()
					.WithCronSchedule(
						cronExpression,
						s => s.InTimeZone(timeZone)
					)
					.Build()
				)
				.ToArray();

			// Quartz.net does not allow scheduling for cron expressions that do not have a fire date in the future.
			// Thus, to avoid throwing an exception, we filter them out
			var triggersToFire = new List<ICronTrigger>(triggers.Length);
			foreach (var trigger in triggers)
			{
				var cronTrigger = (ICronTrigger)trigger;
				if (CanCronTriggerFire(cronTrigger))
				{
					triggersToFire.Add(cronTrigger);
				}
				else
				{
					Log.Warn($"{cronTrigger.CronExpressionString} will not be triggered");
				}
			}

			_scheduler.ScheduleJob(job, triggersToFire, true).Wait();
		}

		private bool CanCronTriggerFire(ICronTrigger cronTrigger)
		{
			return
				cronTrigger.CronExpressionString != null &&
				cronTrigger.GetFireTimeAfter(cronTrigger.StartTimeUtc.AddSeconds(-1)) != null;
		}

		private IJobDetail CreateJob<T>(JobKey jobKey) where T: IJob
		{
			return JobBuilder.Create<T>()
				.WithIdentity(jobKey)
				.UsingJobData("SessionId", _sessionParameters.SessionId.ToString())
				.Build();
		}

		private void DescheduleJob(JobKey key)
		{
			if (JobExists(key))
			{
				_scheduler.DeleteJob(key).Wait();
			}
		}
	}
}