src/test/java/com/google/devtools/build/lib/remote/disk/DiskCacheClientTest.java - bazel - Git at Google

 // Copyright 2024 The Bazel Authors. 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 com.google.devtools.build.lib.remote.disk;

 import static com.google.common.truth.Truth.assertThat;
 import static com.google.devtools.build.lib.remote.util.Utils.getFromFuture;
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.junit.Assert.assertThrows;
 import static org.junit.Assume.assumeNotNull;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;

 import build.bazel.remote.execution.v2.ActionResult;
 import build.bazel.remote.execution.v2.Digest;
 import build.bazel.remote.execution.v2.Directory;
 import build.bazel.remote.execution.v2.FileNode;
 import build.bazel.remote.execution.v2.OutputDirectory;
 import build.bazel.remote.execution.v2.OutputFile;
 import build.bazel.remote.execution.v2.RequestMetadata;
 import build.bazel.remote.execution.v2.Tree;
 import com.google.common.collect.ImmutableList;
 import com.google.common.util.concurrent.MoreExecutors;
 import com.google.devtools.build.lib.actions.Spawn;
 import com.google.devtools.build.lib.exec.SpawnCheckingCacheEvent;
 import com.google.devtools.build.lib.exec.SpawnRunner.SpawnExecutionContext;
 import com.google.devtools.build.lib.remote.Store;
 import com.google.devtools.build.lib.remote.common.CacheNotFoundException;
 import com.google.devtools.build.lib.remote.common.OutputDigestMismatchException;
 import com.google.devtools.build.lib.remote.common.RemoteActionExecutionContext;
 import com.google.devtools.build.lib.remote.common.RemoteCacheClient.ActionKey;
 import com.google.devtools.build.lib.remote.common.RemoteCacheClient.CachedActionResult;
 import com.google.devtools.build.lib.remote.util.DigestUtil;
 import com.google.devtools.build.lib.vfs.DigestHashFunction;
 import com.google.devtools.build.lib.vfs.FileSystem;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.SyscallCache;
 import com.google.devtools.build.lib.vfs.bazel.BazelHashFunctions;
 import com.google.devtools.build.lib.vfs.inmemoryfs.InMemoryFileSystem;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.protobuf.ByteString;
 import com.google.protobuf.Message;
 import java.io.IOException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;

 /** Tests for {@link DiskCacheClient}. */
 @RunWith(JUnit4.class)
 public class DiskCacheClientTest {
   private static final DigestUtil DIGEST_UTIL =
       new DigestUtil(SyscallCache.NO_CACHE, DigestHashFunction.SHA256);
   private static final ExecutorService executorService =
       MoreExecutors.listeningDecorator(Executors.newFixedThreadPool(1));

   private final FileSystem fs = new InMemoryFileSystem(DigestHashFunction.SHA256);
   private final Path root = fs.getPath("/disk_cache");
   private DiskCacheClient client;
   private RemoteActionExecutionContext context;

   @Before
   public void setUp() throws Exception {
     client = new DiskCacheClient(root, DIGEST_UTIL, executorService, /* verifyDownloads= */ true);
     context =
         RemoteActionExecutionContext.create(
             mock(Spawn.class),
             mock(SpawnExecutionContext.class),
             RequestMetadata.getDefaultInstance());
   }

   @Test
   public void downloadActionResult_reportsSpawnCheckingCacheEvent() throws Exception {
     var unused =
         getFromFuture(
             client.downloadActionResult(
                 context,
                 DIGEST_UTIL.asActionKey(DIGEST_UTIL.computeAsUtf8("key")),
                 /* inlineOutErr= */ false));

     verify(context.getSpawnExecutionContext()).report(SpawnCheckingCacheEvent.create("disk-cache"));
   }

   @Test
   public void findMissingDigests_returnsAllDigests() throws Exception {
     ImmutableList<Digest> digests =
         ImmutableList.of(getDigest("foo"), getDigest("bar"), getDigest("baz"));
     assertThat(getFromFuture(client.findMissingDigests(context, digests)))
         .containsExactlyElementsIn(digests);
   }

   @Test
   public void toPath_forCas_forOldStyleHashFunction() throws Exception {
     Digest digest = Digest.newBuilder().setHash("0123456789abcdef").setSizeBytes(42).build();

     Path path = client.toPath(digest, Store.CAS);

     assertThat(path).isEqualTo(root.getRelative("cas/01/0123456789abcdef"));
   }

   @Test
   public void toPath_forAc_forOldStyleHashFunction() throws Exception {
     Digest digest = Digest.newBuilder().setHash("0123456789abcdef").setSizeBytes(42).build();

     Path path = client.toPath(digest, Store.AC);

     assertThat(path).isEqualTo(root.getRelative("ac/01/0123456789abcdef"));
   }

   @Test
   public void toPath_forCas_forNewStyleHashFunction() throws Exception {
     assumeNotNull(BazelHashFunctions.BLAKE3); // BLAKE3 not available in Blaze.

     DiskCacheClient client =
         new DiskCacheClient(
             root,
             new DigestUtil(SyscallCache.NO_CACHE, BazelHashFunctions.BLAKE3),
             executorService,
             /* verifyDownloads= */ true);
     Digest digest = Digest.newBuilder().setHash("0123456789abcdef").setSizeBytes(42).build();
     Path path = client.toPath(digest, Store.CAS);

     assertThat(path).isEqualTo(root.getRelative("blake3/cas/01/0123456789abcdef"));
   }

   @Test
   public void toPath_forAc_forNewStyleHashFunction() throws Exception {
     assumeNotNull(BazelHashFunctions.BLAKE3); // BLAKE3 not available in Blaze.

     DiskCacheClient client =
         new DiskCacheClient(
             root,
             new DigestUtil(SyscallCache.NO_CACHE, BazelHashFunctions.BLAKE3),
             executorService,
             /* verifyDownloads= */ true);
     Digest digest = Digest.newBuilder().setHash("0123456789abcdef").setSizeBytes(42).build();
     Path path = client.toPath(digest, Store.AC);

     assertThat(path).isEqualTo(root.getRelative("blake3/ac/01/0123456789abcdef"));
   }

   @Test
   public void uploadFile_whenMissing_populatesCas() throws Exception {
     assertThat(root.exists()).isTrue();
     Path file = fs.getPath("/file");
     FileSystemUtils.writeContent(file, UTF_8, "contents");
     Digest digest = getDigest("contents");

     var unused = getFromFuture(client.uploadFile(context, digest, file));

     assertThat(FileSystemUtils.readContent(getCasPath(digest), UTF_8)).isEqualTo("contents");
   }

   @Test
   public void uploadFile_whenPresent_updatesMtime() throws Exception {
     Path file = fs.getPath("/file");
     FileSystemUtils.writeContent(file, UTF_8, "contents");
     Digest digest = getDigest("contents");

     // The contents would match under normal operation. This serves to check that we don't
     // unnecessarily overwrite the file.
     Path path = populateCas(digest, "existing contents");

     var unused = getFromFuture(client.uploadFile(context, digest, file));

     assertThat(FileSystemUtils.readContent(path, UTF_8)).isEqualTo("existing contents");
     assertThat(path.getLastModifiedTime()).isNotEqualTo(0);
   }

   @Test
   public void uploadBlob_whenMissing_populatesCas() throws Exception {
     ByteString blob = ByteString.copyFromUtf8("contents");
     Digest digest = getDigest("contents");

     var unused = getFromFuture(client.uploadBlob(context, digest, blob));

     assertThat(FileSystemUtils.readContent(getCasPath(digest), UTF_8)).isEqualTo("contents");
   }

   @Test
   public void uploadBlob_whenPresent_updatesMtime() throws Exception {
     ByteString blob = ByteString.copyFromUtf8("contents");
     Digest digest = getDigest("contents");

     // The contents would match under normal operation. This serves to check that we don't
     // unnecessarily overwrite the file.
     Path path = populateCas(digest, "existing contents");

     var unused = getFromFuture(client.uploadBlob(context, digest, blob));

     assertThat(FileSystemUtils.readContent(path, UTF_8)).isEqualTo("existing contents");
     assertThat(path.getLastModifiedTime()).isNotEqualTo(0);
   }

   @Test
   public void uploadActionResult_whenMissing_populatesAc() throws Exception {
     ActionKey actionKey = new ActionKey(getDigest("key"));
     ActionResult actionResult = ActionResult.newBuilder().setExitCode(42).build();
     Path path = getAcPath(actionKey);

     var unused = getFromFuture(client.uploadActionResult(context, actionKey, actionResult));

     assertThat(FileSystemUtils.readContent(path)).isEqualTo(actionResult.toByteArray());
   }

   @Test
   public void uploadActionResult_whenPresent_updatesMtime() throws Exception {
     ActionKey actionKey = new ActionKey(getDigest("key"));
     ActionResult actionResult = ActionResult.newBuilder().setExitCode(42).build();

     Path path = populateAc(actionKey, actionResult);

     // The contents would match under normal operation. This serves to check that we don't
     // unnecessarily overwrite the file.
     var unused =
         getFromFuture(
             client.uploadActionResult(context, actionKey, ActionResult.getDefaultInstance()));

     assertThat(FileSystemUtils.readContent(path)).isEqualTo(actionResult.toByteArray());
     assertThat(path.getLastModifiedTime()).isNotEqualTo(0);
   }

   @Test
   public void downloadBlob_whenPresent_returnsContents() throws Exception {
     Digest digest = getDigest("contents");
     populateCas(digest, "contents");
     Path out = fs.getPath("/out");

     var unused = getFromFuture(client.downloadBlob(context, digest, out.getOutputStream()));

     assertThat(FileSystemUtils.readContent(out, UTF_8)).isEqualTo("contents");
   }

   @Test
   public void downloadBlob_whenMissing_throwsCacheNotFoundException() throws Exception {
     Path out = fs.getPath("/out");

     assertThrows(
         CacheNotFoundException.class,
         () ->
             getFromFuture(
                 client.downloadBlob(context, getDigest("contents"), out.getOutputStream())));
   }

   @Test
   public void downloadBlob_whenCorrupted_throwsOutputDigestMismatchException() throws Exception {
     Digest digest = getDigest("contents");
     populateCas(digest, "corrupted contents");
     Path out = fs.getPath("/out");

     assertThrows(
         OutputDigestMismatchException.class,
         () -> getFromFuture(client.downloadBlob(context, digest, out.getOutputStream())));
   }

   @Test
   public void downloadActionResult_whenPresent_returnsCachedActionResult() throws Exception {
     ActionKey actionKey = new ActionKey(getDigest("key"));
     ActionResult actionResult = ActionResult.newBuilder().setExitCode(42).build();

     Path path = populateAc(actionKey, actionResult);

     CachedActionResult result =
         getFromFuture(client.downloadActionResult(context, actionKey, /* inlineOutErr= */ false));

     assertThat(result).isEqualTo(CachedActionResult.disk(actionResult));
     assertThat(path.getLastModifiedTime()).isNotEqualTo(0);
   }

   @Test
   public void downloadActionResult_whenMissing_returnsNull() throws Exception {
     ActionKey actionKey = new ActionKey(getDigest("key"));

     CachedActionResult result =
         getFromFuture(client.downloadActionResult(context, actionKey, /* inlineOutErr= */ false));

     assertThat(result).isNull();
   }

   @Test
   public void downloadActionResult_withReferencedBlobsPresent_updatesMtimeOnBlobs()
       throws Exception {
     Digest stdoutDigest = getDigest("stdout contents");
     Digest stderrDigest = getDigest("stderr contents");
     Digest fileDigest = getDigest("file contents");
     Digest treeFileDigest = getDigest("tree file contents");
     Tree tree = getTreeWithFile(treeFileDigest);
     Digest treeDigest = getDigest(tree);
     ActionKey actionKey = new ActionKey(getDigest("key"));
     ActionResult actionResult =
         ActionResult.newBuilder()
             .setStdoutDigest(stdoutDigest)
             .setStderrDigest(stderrDigest)
             .addOutputFiles(OutputFile.newBuilder().setDigest(fileDigest).build())
             .addOutputDirectories(OutputDirectory.newBuilder().setTreeDigest(getDigest(tree)))
             .build();

     Path acPath = populateAc(actionKey, actionResult);
     Path stdoutCasPath = populateCas(stdoutDigest, "stdout contents");
     Path stderrCasPath = populateCas(stderrDigest, "stderr contents");
     Path fileCasPath = populateCas(fileDigest, "file contents");
     Path treeCasPath = populateCas(treeDigest, tree);
     Path treeFileCasPath = populateCas(treeFileDigest, "tree file contents");

     CachedActionResult result =
         getFromFuture(client.downloadActionResult(context, actionKey, /* inlineOutErr= */ false));

     assertThat(result).isEqualTo(CachedActionResult.disk(actionResult));
     assertThat(acPath.getLastModifiedTime()).isNotEqualTo(0);
     assertThat(stdoutCasPath.getLastModifiedTime()).isNotEqualTo(0);
     assertThat(stderrCasPath.getLastModifiedTime()).isNotEqualTo(0);
     assertThat(fileCasPath.getLastModifiedTime()).isNotEqualTo(0);
     assertThat(treeCasPath.getLastModifiedTime()).isNotEqualTo(0);
     assertThat(treeFileCasPath.getLastModifiedTime()).isNotEqualTo(0);
   }

   @Test
   public void downloadActionResult_withReferencedFileMissing_returnsNull() throws Exception {
     Digest fileDigest = getDigest("contents");
     ActionKey actionKey = new ActionKey(getDigest("key"));
     ActionResult actionResult =
         ActionResult.newBuilder()
             .addOutputFiles(OutputFile.newBuilder().setDigest(fileDigest).build())
             .build();

     populateAc(actionKey, actionResult);

     CachedActionResult result =
         getFromFuture(client.downloadActionResult(context, actionKey, /* inlineOutErr= */ false));

     assertThat(result).isNull();
   }

   @Test
   public void downloadActionResult_withReferencedTreeMissing_returnsNull() throws Exception {
     Digest fileDigest = getDigest("contents");
     Tree tree = getTreeWithFile(fileDigest);
     Digest treeDigest = getDigest(tree);
     ActionKey actionKey = new ActionKey(getDigest("key"));
     ActionResult actionResult =
         ActionResult.newBuilder()
             .addOutputDirectories(OutputDirectory.newBuilder().setTreeDigest(treeDigest))
             .build();

     populateAc(actionKey, actionResult);
     populateCas(fileDigest, "contents");

     CachedActionResult result =
         getFromFuture(client.downloadActionResult(context, actionKey, /* inlineOutErr= */ false));

     assertThat(result).isNull();
   }

   @Test
   public void downloadActionResult_withReferencedTreeFileMissing_returnsNull() throws Exception {
     Digest fileDigest = getDigest("contents");
     Tree tree = getTreeWithFile(fileDigest);
     Digest treeDigest = getDigest(tree);
     ActionKey actionKey = new ActionKey(getDigest("key"));
     ActionResult actionResult =
         ActionResult.newBuilder()
             .addOutputDirectories(OutputDirectory.newBuilder().setTreeDigest(treeDigest))
             .build();

     populateAc(actionKey, actionResult);
     populateCas(treeDigest, tree);

     CachedActionResult result =
         getFromFuture(client.downloadActionResult(context, actionKey, /* inlineOutErr= */ false));

     assertThat(result).isNull();
   }

   private Tree getTreeWithFile(Digest fileDigest) {
     return Tree.newBuilder()
         .addChildren(Directory.newBuilder().addFiles(FileNode.newBuilder().setDigest(fileDigest)))
         .build();
   }

   private Path getCasPath(Digest digest) {
     return client.toPath(digest, Store.CAS);
   }

   @CanIgnoreReturnValue
   private Path populateCas(Digest digest, String contents) throws IOException {
     return populateCas(digest, contents.getBytes(UTF_8));
   }

   @CanIgnoreReturnValue
   private Path populateCas(Digest digest, Message m) throws IOException {
     return populateCas(digest, m.toByteArray());
   }

   private Path populateCas(Digest digest, byte[] contents) throws IOException {
     Path path = getCasPath(digest);
     path.getParentDirectory().createDirectoryAndParents();
     FileSystemUtils.writeContent(path, contents);
     path.setLastModifiedTime(0);
     return path;
   }

   private Path getAcPath(ActionKey actionKey) {
     return client.toPath(actionKey.getDigest(), Store.AC);
   }

   @CanIgnoreReturnValue
   private Path populateAc(ActionKey actionKey, ActionResult actionResult) throws IOException {
     Path path = getAcPath(actionKey);
     path.getParentDirectory().createDirectoryAndParents();
     FileSystemUtils.writeContent(path, actionResult.toByteArray());
     path.setLastModifiedTime(0);
     return path;
   }

   private Digest getDigest(String contents) {
     return DIGEST_UTIL.computeAsUtf8(contents);
   }

   private Digest getDigest(Message m) {
     return DIGEST_UTIL.compute(m.toByteArray());
   }
 }
	// Copyright 2024 The Bazel Authors. 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 com.google.devtools.build.lib.remote.disk;

	import static com.google.common.truth.Truth.assertThat;
	import static com.google.devtools.build.lib.remote.util.Utils.getFromFuture;
	import static java.nio.charset.StandardCharsets.UTF_8;
	import static org.junit.Assert.assertThrows;
	import static org.junit.Assume.assumeNotNull;
	import static org.mockito.Mockito.mock;
	import static org.mockito.Mockito.verify;

	import build.bazel.remote.execution.v2.ActionResult;
	import build.bazel.remote.execution.v2.Digest;
	import build.bazel.remote.execution.v2.Directory;
	import build.bazel.remote.execution.v2.FileNode;
	import build.bazel.remote.execution.v2.OutputDirectory;
	import build.bazel.remote.execution.v2.OutputFile;
	import build.bazel.remote.execution.v2.RequestMetadata;
	import build.bazel.remote.execution.v2.Tree;
	import com.google.common.collect.ImmutableList;
	import com.google.common.util.concurrent.MoreExecutors;
	import com.google.devtools.build.lib.actions.Spawn;
	import com.google.devtools.build.lib.exec.SpawnCheckingCacheEvent;
	import com.google.devtools.build.lib.exec.SpawnRunner.SpawnExecutionContext;
	import com.google.devtools.build.lib.remote.Store;
	import com.google.devtools.build.lib.remote.common.CacheNotFoundException;
	import com.google.devtools.build.lib.remote.common.OutputDigestMismatchException;
	import com.google.devtools.build.lib.remote.common.RemoteActionExecutionContext;
	import com.google.devtools.build.lib.remote.common.RemoteCacheClient.ActionKey;
	import com.google.devtools.build.lib.remote.common.RemoteCacheClient.CachedActionResult;
	import com.google.devtools.build.lib.remote.util.DigestUtil;
	import com.google.devtools.build.lib.vfs.DigestHashFunction;
	import com.google.devtools.build.lib.vfs.FileSystem;
	import com.google.devtools.build.lib.vfs.FileSystemUtils;
	import com.google.devtools.build.lib.vfs.Path;
	import com.google.devtools.build.lib.vfs.SyscallCache;
	import com.google.devtools.build.lib.vfs.bazel.BazelHashFunctions;
	import com.google.devtools.build.lib.vfs.inmemoryfs.InMemoryFileSystem;
	import com.google.errorprone.annotations.CanIgnoreReturnValue;
	import com.google.protobuf.ByteString;
	import com.google.protobuf.Message;
	import java.io.IOException;
	import java.util.concurrent.ExecutorService;
	import java.util.concurrent.Executors;
	import org.junit.Before;
	import org.junit.Test;
	import org.junit.runner.RunWith;
	import org.junit.runners.JUnit4;

	/** Tests for {@link DiskCacheClient}. */
	@RunWith(JUnit4.class)
	public class DiskCacheClientTest {
	private static final DigestUtil DIGEST_UTIL =
	new DigestUtil(SyscallCache.NO_CACHE, DigestHashFunction.SHA256);
	private static final ExecutorService executorService =
	MoreExecutors.listeningDecorator(Executors.newFixedThreadPool(1));

	private final FileSystem fs = new InMemoryFileSystem(DigestHashFunction.SHA256);
	private final Path root = fs.getPath("/disk_cache");
	private DiskCacheClient client;
	private RemoteActionExecutionContext context;

	@Before
	public void setUp() throws Exception {
	client = new DiskCacheClient(root, DIGEST_UTIL, executorService, /* verifyDownloads= */ true);
	context =
	RemoteActionExecutionContext.create(
	mock(Spawn.class),
	mock(SpawnExecutionContext.class),
	RequestMetadata.getDefaultInstance());
	}

	@Test
	public void downloadActionResult_reportsSpawnCheckingCacheEvent() throws Exception {
	var unused =
	getFromFuture(
	client.downloadActionResult(
	context,
	DIGEST_UTIL.asActionKey(DIGEST_UTIL.computeAsUtf8("key")),
	/* inlineOutErr= */ false));

	verify(context.getSpawnExecutionContext()).report(SpawnCheckingCacheEvent.create("disk-cache"));
	}

	@Test
	public void findMissingDigests_returnsAllDigests() throws Exception {
	ImmutableList<Digest> digests =
	ImmutableList.of(getDigest("foo"), getDigest("bar"), getDigest("baz"));
	assertThat(getFromFuture(client.findMissingDigests(context, digests)))
	.containsExactlyElementsIn(digests);
	}

	@Test
	public void toPath_forCas_forOldStyleHashFunction() throws Exception {
	Digest digest = Digest.newBuilder().setHash("0123456789abcdef").setSizeBytes(42).build();

	Path path = client.toPath(digest, Store.CAS);

	assertThat(path).isEqualTo(root.getRelative("cas/01/0123456789abcdef"));
	}

	@Test
	public void toPath_forAc_forOldStyleHashFunction() throws Exception {
	Digest digest = Digest.newBuilder().setHash("0123456789abcdef").setSizeBytes(42).build();

	Path path = client.toPath(digest, Store.AC);

	assertThat(path).isEqualTo(root.getRelative("ac/01/0123456789abcdef"));
	}

	@Test
	public void toPath_forCas_forNewStyleHashFunction() throws Exception {
	assumeNotNull(BazelHashFunctions.BLAKE3); // BLAKE3 not available in Blaze.

	DiskCacheClient client =
	new DiskCacheClient(
	root,
	new DigestUtil(SyscallCache.NO_CACHE, BazelHashFunctions.BLAKE3),
	executorService,
	/* verifyDownloads= */ true);
	Digest digest = Digest.newBuilder().setHash("0123456789abcdef").setSizeBytes(42).build();
	Path path = client.toPath(digest, Store.CAS);

	assertThat(path).isEqualTo(root.getRelative("blake3/cas/01/0123456789abcdef"));
	}

	@Test
	public void toPath_forAc_forNewStyleHashFunction() throws Exception {
	assumeNotNull(BazelHashFunctions.BLAKE3); // BLAKE3 not available in Blaze.

	DiskCacheClient client =
	new DiskCacheClient(
	root,
	new DigestUtil(SyscallCache.NO_CACHE, BazelHashFunctions.BLAKE3),
	executorService,
	/* verifyDownloads= */ true);
	Digest digest = Digest.newBuilder().setHash("0123456789abcdef").setSizeBytes(42).build();
	Path path = client.toPath(digest, Store.AC);

	assertThat(path).isEqualTo(root.getRelative("blake3/ac/01/0123456789abcdef"));
	}

	@Test
	public void uploadFile_whenMissing_populatesCas() throws Exception {
	assertThat(root.exists()).isTrue();
	Path file = fs.getPath("/file");
	FileSystemUtils.writeContent(file, UTF_8, "contents");
	Digest digest = getDigest("contents");

	var unused = getFromFuture(client.uploadFile(context, digest, file));

	assertThat(FileSystemUtils.readContent(getCasPath(digest), UTF_8)).isEqualTo("contents");
	}

	@Test
	public void uploadFile_whenPresent_updatesMtime() throws Exception {
	Path file = fs.getPath("/file");
	FileSystemUtils.writeContent(file, UTF_8, "contents");
	Digest digest = getDigest("contents");

	// The contents would match under normal operation. This serves to check that we don't
	// unnecessarily overwrite the file.
	Path path = populateCas(digest, "existing contents");

	var unused = getFromFuture(client.uploadFile(context, digest, file));

	assertThat(FileSystemUtils.readContent(path, UTF_8)).isEqualTo("existing contents");
	assertThat(path.getLastModifiedTime()).isNotEqualTo(0);
	}

	@Test
	public void uploadBlob_whenMissing_populatesCas() throws Exception {
	ByteString blob = ByteString.copyFromUtf8("contents");
	Digest digest = getDigest("contents");

	var unused = getFromFuture(client.uploadBlob(context, digest, blob));

	assertThat(FileSystemUtils.readContent(getCasPath(digest), UTF_8)).isEqualTo("contents");
	}

	@Test
	public void uploadBlob_whenPresent_updatesMtime() throws Exception {
	ByteString blob = ByteString.copyFromUtf8("contents");
	Digest digest = getDigest("contents");

	// The contents would match under normal operation. This serves to check that we don't
	// unnecessarily overwrite the file.
	Path path = populateCas(digest, "existing contents");

	var unused = getFromFuture(client.uploadBlob(context, digest, blob));

	assertThat(FileSystemUtils.readContent(path, UTF_8)).isEqualTo("existing contents");
	assertThat(path.getLastModifiedTime()).isNotEqualTo(0);
	}

	@Test
	public void uploadActionResult_whenMissing_populatesAc() throws Exception {
	ActionKey actionKey = new ActionKey(getDigest("key"));
	ActionResult actionResult = ActionResult.newBuilder().setExitCode(42).build();
	Path path = getAcPath(actionKey);

	var unused = getFromFuture(client.uploadActionResult(context, actionKey, actionResult));

	assertThat(FileSystemUtils.readContent(path)).isEqualTo(actionResult.toByteArray());
	}

	@Test
	public void uploadActionResult_whenPresent_updatesMtime() throws Exception {
	ActionKey actionKey = new ActionKey(getDigest("key"));
	ActionResult actionResult = ActionResult.newBuilder().setExitCode(42).build();

	Path path = populateAc(actionKey, actionResult);

	// The contents would match under normal operation. This serves to check that we don't
	// unnecessarily overwrite the file.
	var unused =
	getFromFuture(
	client.uploadActionResult(context, actionKey, ActionResult.getDefaultInstance()));

	assertThat(FileSystemUtils.readContent(path)).isEqualTo(actionResult.toByteArray());
	assertThat(path.getLastModifiedTime()).isNotEqualTo(0);
	}

	@Test
	public void downloadBlob_whenPresent_returnsContents() throws Exception {
	Digest digest = getDigest("contents");
	populateCas(digest, "contents");
	Path out = fs.getPath("/out");

	var unused = getFromFuture(client.downloadBlob(context, digest, out.getOutputStream()));

	assertThat(FileSystemUtils.readContent(out, UTF_8)).isEqualTo("contents");
	}

	@Test
	public void downloadBlob_whenMissing_throwsCacheNotFoundException() throws Exception {
	Path out = fs.getPath("/out");

	assertThrows(
	CacheNotFoundException.class,
	() ->
	getFromFuture(
	client.downloadBlob(context, getDigest("contents"), out.getOutputStream())));
	}

	@Test
	public void downloadBlob_whenCorrupted_throwsOutputDigestMismatchException() throws Exception {
	Digest digest = getDigest("contents");
	populateCas(digest, "corrupted contents");
	Path out = fs.getPath("/out");

	assertThrows(
	OutputDigestMismatchException.class,
	() -> getFromFuture(client.downloadBlob(context, digest, out.getOutputStream())));
	}

	@Test
	public void downloadActionResult_whenPresent_returnsCachedActionResult() throws Exception {
	ActionKey actionKey = new ActionKey(getDigest("key"));
	ActionResult actionResult = ActionResult.newBuilder().setExitCode(42).build();

	Path path = populateAc(actionKey, actionResult);

	CachedActionResult result =
	getFromFuture(client.downloadActionResult(context, actionKey, /* inlineOutErr= */ false));

	assertThat(result).isEqualTo(CachedActionResult.disk(actionResult));
	assertThat(path.getLastModifiedTime()).isNotEqualTo(0);
	}

	@Test
	public void downloadActionResult_whenMissing_returnsNull() throws Exception {
	ActionKey actionKey = new ActionKey(getDigest("key"));

	CachedActionResult result =
	getFromFuture(client.downloadActionResult(context, actionKey, /* inlineOutErr= */ false));

	assertThat(result).isNull();
	}

	@Test
	public void downloadActionResult_withReferencedBlobsPresent_updatesMtimeOnBlobs()
	throws Exception {
	Digest stdoutDigest = getDigest("stdout contents");
	Digest stderrDigest = getDigest("stderr contents");
	Digest fileDigest = getDigest("file contents");
	Digest treeFileDigest = getDigest("tree file contents");
	Tree tree = getTreeWithFile(treeFileDigest);
	Digest treeDigest = getDigest(tree);
	ActionKey actionKey = new ActionKey(getDigest("key"));
	ActionResult actionResult =
	ActionResult.newBuilder()
	.setStdoutDigest(stdoutDigest)
	.setStderrDigest(stderrDigest)
	.addOutputFiles(OutputFile.newBuilder().setDigest(fileDigest).build())
	.addOutputDirectories(OutputDirectory.newBuilder().setTreeDigest(getDigest(tree)))
	.build();

	Path acPath = populateAc(actionKey, actionResult);
	Path stdoutCasPath = populateCas(stdoutDigest, "stdout contents");
	Path stderrCasPath = populateCas(stderrDigest, "stderr contents");
	Path fileCasPath = populateCas(fileDigest, "file contents");
	Path treeCasPath = populateCas(treeDigest, tree);
	Path treeFileCasPath = populateCas(treeFileDigest, "tree file contents");

	CachedActionResult result =
	getFromFuture(client.downloadActionResult(context, actionKey, /* inlineOutErr= */ false));

	assertThat(result).isEqualTo(CachedActionResult.disk(actionResult));
	assertThat(acPath.getLastModifiedTime()).isNotEqualTo(0);
	assertThat(stdoutCasPath.getLastModifiedTime()).isNotEqualTo(0);
	assertThat(stderrCasPath.getLastModifiedTime()).isNotEqualTo(0);
	assertThat(fileCasPath.getLastModifiedTime()).isNotEqualTo(0);
	assertThat(treeCasPath.getLastModifiedTime()).isNotEqualTo(0);
	assertThat(treeFileCasPath.getLastModifiedTime()).isNotEqualTo(0);
	}

	@Test
	public void downloadActionResult_withReferencedFileMissing_returnsNull() throws Exception {
	Digest fileDigest = getDigest("contents");
	ActionKey actionKey = new ActionKey(getDigest("key"));
	ActionResult actionResult =
	ActionResult.newBuilder()
	.addOutputFiles(OutputFile.newBuilder().setDigest(fileDigest).build())
	.build();

	populateAc(actionKey, actionResult);

	CachedActionResult result =
	getFromFuture(client.downloadActionResult(context, actionKey, /* inlineOutErr= */ false));

	assertThat(result).isNull();
	}

	@Test
	public void downloadActionResult_withReferencedTreeMissing_returnsNull() throws Exception {
	Digest fileDigest = getDigest("contents");
	Tree tree = getTreeWithFile(fileDigest);
	Digest treeDigest = getDigest(tree);
	ActionKey actionKey = new ActionKey(getDigest("key"));
	ActionResult actionResult =
	ActionResult.newBuilder()
	.addOutputDirectories(OutputDirectory.newBuilder().setTreeDigest(treeDigest))
	.build();

	populateAc(actionKey, actionResult);
	populateCas(fileDigest, "contents");

	CachedActionResult result =
	getFromFuture(client.downloadActionResult(context, actionKey, /* inlineOutErr= */ false));

	assertThat(result).isNull();
	}

	@Test
	public void downloadActionResult_withReferencedTreeFileMissing_returnsNull() throws Exception {
	Digest fileDigest = getDigest("contents");
	Tree tree = getTreeWithFile(fileDigest);
	Digest treeDigest = getDigest(tree);
	ActionKey actionKey = new ActionKey(getDigest("key"));
	ActionResult actionResult =
	ActionResult.newBuilder()
	.addOutputDirectories(OutputDirectory.newBuilder().setTreeDigest(treeDigest))
	.build();

	populateAc(actionKey, actionResult);
	populateCas(treeDigest, tree);

	CachedActionResult result =
	getFromFuture(client.downloadActionResult(context, actionKey, /* inlineOutErr= */ false));

	assertThat(result).isNull();
	}

	private Tree getTreeWithFile(Digest fileDigest) {
	return Tree.newBuilder()
	.addChildren(Directory.newBuilder().addFiles(FileNode.newBuilder().setDigest(fileDigest)))
	.build();
	}

	private Path getCasPath(Digest digest) {
	return client.toPath(digest, Store.CAS);
	}

	@CanIgnoreReturnValue
	private Path populateCas(Digest digest, String contents) throws IOException {
	return populateCas(digest, contents.getBytes(UTF_8));
	}

	@CanIgnoreReturnValue
	private Path populateCas(Digest digest, Message m) throws IOException {
	return populateCas(digest, m.toByteArray());
	}

	private Path populateCas(Digest digest, byte[] contents) throws IOException {
	Path path = getCasPath(digest);
	path.getParentDirectory().createDirectoryAndParents();
	FileSystemUtils.writeContent(path, contents);
	path.setLastModifiedTime(0);
	return path;
	}

	private Path getAcPath(ActionKey actionKey) {
	return client.toPath(actionKey.getDigest(), Store.AC);
	}

	@CanIgnoreReturnValue
	private Path populateAc(ActionKey actionKey, ActionResult actionResult) throws IOException {
	Path path = getAcPath(actionKey);
	path.getParentDirectory().createDirectoryAndParents();
	FileSystemUtils.writeContent(path, actionResult.toByteArray());
	path.setLastModifiedTime(0);
	return path;
	}

	private Digest getDigest(String contents) {
	return DIGEST_UTIL.computeAsUtf8(contents);
	}

	private Digest getDigest(Message m) {
	return DIGEST_UTIL.compute(m.toByteArray());
	}
	}