/*
    * Copyright (C) 2012, Christian Halstrick <christian.halstrick@sap.com> and others
    *
    * This program and the accompanying materials are made available under the
    * terms of the Eclipse Distribution License v. 1.0 which is available at
    * https://www.eclipse.org/org/documents/edl-v10.php.
    *
    * SPDX-License-Identifier: BSD-3-Clause
    */
  
  package org.eclipse.jgit.internal.storage.file;
  
  import static java.lang.Integer.valueOf;
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertNotEquals;
  import static org.junit.Assert.assertNotNull;
  import static org.junit.Assert.assertTrue;
  import static org.junit.Assert.fail;
  
  import java.io.IOException;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.concurrent.BrokenBarrierException;
  import java.util.concurrent.Callable;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.CyclicBarrier;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import java.util.concurrent.Future;
  import java.util.concurrent.TimeUnit;
  
  import org.eclipse.jgit.errors.CancelledException;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.internal.storage.pack.PackWriter;
  import org.eclipse.jgit.junit.TestRepository;
  import org.eclipse.jgit.lib.ConfigConstants;
  import org.eclipse.jgit.lib.EmptyProgressMonitor;
  import org.eclipse.jgit.lib.NullProgressMonitor;
  import org.eclipse.jgit.lib.ObjectId;
  import org.eclipse.jgit.lib.Sets;
  import org.eclipse.jgit.revwalk.RevBlob;
  import org.eclipse.jgit.revwalk.RevCommit;
  import org.eclipse.jgit.storage.file.FileBasedConfig;
  import org.eclipse.jgit.test.resources.SampleDataRepositoryTestCase;
  import org.junit.Test;
  
  public class GcConcurrentTest extends GcTestCase {
  	@Test
  	public void concurrentRepack() throws Exception {
  		final CyclicBarrier syncPoint = new CyclicBarrier(2);
  
  		class DoRepack extends EmptyProgressMonitor implements
  				Callable<Integer> {
  
  			@Override
  			public void beginTask(String title, int totalWork) {
  				if (title.equals(JGitText.get().writingObjects)) {
  					try {
  						syncPoint.await();
  					} catch (InterruptedException e) {
  						Thread.currentThread().interrupt();
  					} catch (BrokenBarrierException ignored) {
  						//
  					}
  				}
  			}
  
  			/** @return 0 for success, 1 in case of error when writing pack */
  			@Override
  			public Integer call() throws Exception {
  				try {
  					gc.setProgressMonitor(this);
  					gc.repack();
  					return valueOf(0);
  				} catch (IOException e) {
  					// leave the syncPoint in broken state so any awaiting
  					// threads and any threads that call await in the future get
  					// the BrokenBarrierException
  					Thread.currentThread().interrupt();
  					try {
  						syncPoint.await();
  					} catch (InterruptedException ignored) {
  						//
  					}
  					return valueOf(1);
  				}
  			}
  		}
  
  		RevBlob a = tr.blob("a");
  		tr.lightweightTag("t", a);
  
  		ExecutorService pool = Executors.newFixedThreadPool(2);
  		try {
  			DoRepack repack1 = new DoRepack();
  			DoRepack repack2 = new DoRepack();
  			Future<Integer> result1 = pool.submit(repack1);
  			Future<Integer> result2 = pool.submit(repack2);
 			assertEquals(0, result1.get().intValue() + result2.get().intValue());
 		} finally {
 			pool.shutdown();
 			pool.awaitTermination(Long.MAX_VALUE, TimeUnit.SECONDS);
 		}
 	}
 
 	@Test
 	public void repackAndGetStats() throws Exception {
 		TestRepository<FileRepository>.BranchBuilder test = tr.branch("test");
 		test.commit().add("a", "a").create();
 		GC gc1 = new GC(tr.getRepository());
 		gc1.setPackExpireAgeMillis(0);
 		gc1.gc().get();
 		test.commit().add("b", "b").create();
 
 		// Create a new Repository instance and trigger a gc
 		// from that instance. Reusing the existing repo instance
 		// tr.getRepository() would not show the problem.
 		FileRepository r2 = new FileRepository(
 				tr.getRepository().getDirectory());
 		GC gc2 = new GC(r2);
 		gc2.setPackExpireAgeMillis(0);
 		gc2.gc().get();
 
 		new GC(tr.getRepository()).getStatistics();
 	}
 
 	@Test
 	public void repackAndUploadPack() throws Exception {
 		TestRepository<FileRepository>.BranchBuilder test = tr.branch("test");
 		// RevCommit a = test.commit().add("a", "a").create();
 		test.commit().add("a", "a").create();
 
 		GC gc1 = new GC(tr.getRepository());
 		gc1.setPackExpireAgeMillis(0);
 		gc1.gc().get();
 
 		RevCommit b = test.commit().add("b", "b").create();
 
 		FileRepository r2 = new FileRepository(
 				tr.getRepository().getDirectory());
 		GC gc2 = new GC(r2);
 		gc2.setPackExpireAgeMillis(0);
 		gc2.gc().get();
 
 		// Simulate parts of an UploadPack. This is the situation on
 		// server side (e.g. gerrit) when clients are
 		// cloning/fetching while the server side repo's
 		// are gc'ed by an external process (e.g. scheduled
 		// native git gc)
 		try (PackWriter pw = new PackWriter(tr.getRepository())) {
 			pw.setUseBitmaps(true);
 			pw.preparePack(NullProgressMonitor.INSTANCE, Sets.of(b),
 					Collections.<ObjectId> emptySet());
 			new GC(tr.getRepository()).getStatistics();
 		}
 	}
 
 	Pack getSinglePack(FileRepository r) {
 		Collection<Pack> packs = r.getObjectDatabase().getPacks();
 		assertEquals(1, packs.size());
 		return packs.iterator().next();
 	}
 
 	@Test
 	public void repackAndCheckBitmapUsage() throws Exception {
 		// create a test repository with one commit and pack all objects. After
 		// packing create loose objects to trigger creation of a new packfile on
 		// the next gc
 		TestRepository<FileRepository>.BranchBuilder test = tr.branch("test");
 		test.commit().add("a", "a").create();
 		FileRepository repository = tr.getRepository();
 		GC gc1 = new GC(repository);
 		gc1.setPackExpireAgeMillis(0);
 		gc1.gc().get();
 		String oldPackName = getSinglePack(repository).getPackName();
 		RevCommit b = test.commit().add("b", "b").create();
 
 		// start the garbage collection on a new repository instance,
 		FileRepository repository2 = new FileRepository(repository.getDirectory());
 		GC gc2 = new GC(repository2);
 		gc2.setPackExpireAgeMillis(0);
 		gc2.gc().get();
 		String newPackName = getSinglePack(repository2).getPackName();
 		// make sure gc() has caused creation of a new packfile
 		assertNotEquals(oldPackName, newPackName);
 
 		// Even when asking again for the set of packfiles outdated data
 		// will be returned. As long as the repository can work on cached data
 		// it will do so and not detect that a new packfile exists.
 		assertNotEquals(getSinglePack(repository).getPackName(), newPackName);
 
 		// Only when accessing object content it is required to rescan the pack
 		// directory and the new packfile will be detected.
 		repository.getObjectDatabase().open(b).getSize();
 		assertEquals(getSinglePack(repository).getPackName(), newPackName);
 		assertNotNull(getSinglePack(repository).getBitmapIndex());
 	}
 
 	@Test
 	public void testInterruptGc() throws Exception {
 		FileBasedConfig c = repo.getConfig();
 		c.setInt(ConfigConstants.CONFIG_GC_SECTION, null,
 				ConfigConstants.CONFIG_KEY_AUTOPACKLIMIT, 1);
 		c.save();
 		SampleDataRepositoryTestCase.copyCGitTestPacks(repo);
 		ExecutorService executor = Executors.newSingleThreadExecutor();
 		final CountDownLatch latch = new CountDownLatch(1);
 		Future<Collection<Pack>> result = executor.submit(() -> {
 			long start = System.currentTimeMillis();
 			System.out.println("starting gc");
 			latch.countDown();
 			Collection<Pack> r = gc.gc().get();
 			System.out.println(
 					"gc took " + (System.currentTimeMillis() - start) + " ms");
 			return r;
 		});
 		try {
 			latch.await();
 			Thread.sleep(5);
 			executor.shutdownNow();
 			result.get();
 			fail("thread wasn't interrupted");
 		} catch (ExecutionException e) {
 			Throwable cause = e.getCause();
 			if (cause instanceof CancelledException) {
 				assertEquals(JGitText.get().operationCanceled,
 						cause.getMessage());
 			} else if (cause instanceof IOException) {
 				Throwable cause2 = cause.getCause();
 				assertTrue(cause2 instanceof InterruptedException
 						|| cause2 instanceof ExecutionException);
 			} else {
 				fail("unexpected exception " + e);
 			}
 		}
 	}
 }