Merge pull request #24390 from vespa-engine/revert-24368-hmusum/refactor-cleanup-of-file-references

Revert "Refactor cleanup of file references"

8 files changed, 139 insertions, 179 deletions

diff --git a/config-proxy/pom.xml b/config-proxy/pom.xml
index bd1f907f87e..476f5f99b86 100644
--- a/config-proxy/pom.xml
+++ b/config-proxy/pom.xml
@@ -74,12 +74,6 @@
       <version>${project.version}</version>
       <scope>compile</scope>
     </dependency>
-    <dependency>
-      <groupId>com.yahoo.vespa</groupId>
-      <artifactId>testutil</artifactId>
-      <version>${project.version}</version>
-      <scope>test</scope>
-    </dependency>
   </dependencies>
   <build>
     <plugins>
diff --git a/config-proxy/src/main/java/com/yahoo/vespa/config/proxy/filedistribution/CachedFilesMaintainer.java b/config-proxy/src/main/java/com/yahoo/vespa/config/proxy/filedistribution/CachedFilesMaintainer.java
index a3dd8d27c0f..3eafdf8f2b4 100644
--- a/config-proxy/src/main/java/com/yahoo/vespa/config/proxy/filedistribution/CachedFilesMaintainer.java
+++ b/config-proxy/src/main/java/com/yahoo/vespa/config/proxy/filedistribution/CachedFilesMaintainer.java
@@ -1,17 +1,27 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.config.proxy.filedistribution;
 
+import com.yahoo.io.IOUtils;
+import java.util.logging.Level;
 import com.yahoo.vespa.filedistribution.FileDownloader;
-import com.yahoo.vespa.filedistribution.maintenance.FileDistributionCleanup;
+
 import java.io.File;
-import java.time.Clock;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.attribute.BasicFileAttributes;
 import java.time.Duration;
+import java.time.Instant;
+import java.util.Arrays;
+import java.util.HashSet;
 import java.util.Set;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import java.util.stream.Collectors;
+
+import static java.nio.file.Files.readAttributes;
 
 /**
- * Deletes file references and url downloads on disk that have not been used for some time
+ * Deletes cached file references and url downloads that have not been used for some time
  *
  * @author hmusum
  */
@@ -21,29 +31,20 @@ class CachedFilesMaintainer implements Runnable {
 
     private static final File defaultUrlDownloadDir = UrlDownloadRpcServer.downloadDir;
     private static final File defaultFileReferencesDownloadDir = FileDownloader.defaultDownloadDirectory;
-    private static final Duration defaultDurationToKeepFiles = Duration.ofDays(20);
-    private static final int defaultKeepCount = 20;
+    private static final Duration defaultDurationToKeepFiles = Duration.ofDays(30);
 
     private final File urlDownloadDir;
     private final File fileReferencesDownloadDir;
     private final Duration durationToKeepFiles;
-    private final FileDistributionCleanup cleanup;
-    private final int keepCount;  // keep this many files no matter how old they are or when they were last accessed
 
     CachedFilesMaintainer() {
-        this(defaultFileReferencesDownloadDir, defaultUrlDownloadDir, defaultDurationToKeepFiles, Clock.systemUTC(), defaultKeepCount);
+        this(defaultFileReferencesDownloadDir, defaultUrlDownloadDir, defaultDurationToKeepFiles);
     }
 
-    CachedFilesMaintainer(File fileReferencesDownloadDir,
-                          File urlDownloadDir,
-                          Duration durationToKeepFiles,
-                          Clock clock,
-                          int keepCount) {
+    CachedFilesMaintainer(File fileReferencesDownloadDir, File urlDownloadDir, Duration durationToKeepFiles) {
         this.fileReferencesDownloadDir = fileReferencesDownloadDir;
         this.urlDownloadDir = urlDownloadDir;
         this.durationToKeepFiles = durationToKeepFiles;
-        this.cleanup = new FileDistributionCleanup(clock);
-        this.keepCount = keepCount;
     }
 
     @Override
@@ -57,7 +58,35 @@ class CachedFilesMaintainer implements Runnable {
     }
 
     private void deleteUnusedFiles(File directory) {
-        cleanup.deleteUnusedFileReferences(directory, durationToKeepFiles, keepCount, Set.of());
+        Instant deleteNotUsedSinceInstant = Instant.now().minus(durationToKeepFiles);
+        Set<String> filesOnDisk = new HashSet<>();
+        File[] files = directory.listFiles();
+        if (files != null)
+            filesOnDisk.addAll(Arrays.stream(files).map(File::getName).collect(Collectors.toSet()));
+        log.log(Level.FINE, () -> "Files on disk (in " + directory + "): " + filesOnDisk);
+
+        Set<String> filesToDelete = filesOnDisk
+                .stream()
+                .filter(fileReference -> isFileLastModifiedBefore(new File(directory, fileReference), deleteNotUsedSinceInstant))
+                .collect(Collectors.toSet());
+        if (filesToDelete.size() > 0) {
+            log.log(Level.INFO, "Files that can be deleted in " + directory + " (not used since " + deleteNotUsedSinceInstant + "): " + filesToDelete);
+            filesToDelete.forEach(fileReference -> {
+                File file = new File(directory, fileReference);
+                if (!IOUtils.recursiveDeleteDir(file))
+                    log.log(Level.WARNING, "Could not delete " + file.getAbsolutePath());
+            });
+        }
+    }
+
+    private boolean isFileLastModifiedBefore(File fileReference, Instant instant) {
+        BasicFileAttributes fileAttributes;
+        try {
+            fileAttributes = readAttributes(fileReference.toPath(), BasicFileAttributes.class);
+            return fileAttributes.lastModifiedTime().toInstant().isBefore(instant);
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
     }
 
 }
diff --git a/config-proxy/src/test/java/com/yahoo/vespa/config/proxy/filedistribution/CachedFilesMaintainerTest.java b/config-proxy/src/test/java/com/yahoo/vespa/config/proxy/filedistribution/CachedFilesMaintainerTest.java
index 835982be44c..a491a7b4fc4 100644
--- a/config-proxy/src/test/java/com/yahoo/vespa/config/proxy/filedistribution/CachedFilesMaintainerTest.java
+++ b/config-proxy/src/test/java/com/yahoo/vespa/config/proxy/filedistribution/CachedFilesMaintainerTest.java
@@ -2,17 +2,14 @@
 package com.yahoo.vespa.config.proxy.filedistribution;
 
 import com.yahoo.io.IOUtils;
-import com.yahoo.test.ManualClock;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
+
 import java.io.File;
 import java.io.IOException;
-import java.io.UncheckedIOException;
-import java.nio.file.Files;
-import java.nio.file.attribute.FileTime;
 import java.time.Duration;
-import java.util.stream.IntStream;
+import java.time.Instant;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
@@ -22,12 +19,9 @@ import static org.junit.jupiter.api.Assertions.assertNotNull;
  */
 public class CachedFilesMaintainerTest {
 
-    private static final int numberToAlwaysKeep = 2;
-
     private File cachedFileReferences;
     private File cachedDownloads;
     private CachedFilesMaintainer cachedFilesMaintainer;
-    private final ManualClock clock = new ManualClock();
 
     @TempDir
     public File tempFolder;
@@ -36,28 +30,28 @@ public class CachedFilesMaintainerTest {
     public void setup() throws IOException {
         cachedFileReferences = newFolder(tempFolder, "cachedFileReferences");
         cachedDownloads = newFolder(tempFolder, "cachedDownloads");
-        cachedFilesMaintainer = new CachedFilesMaintainer(cachedFileReferences,
-                                                          cachedDownloads,
-                                                          Duration.ofMinutes(2),
-                                                          clock,
-                                                          numberToAlwaysKeep);
+        cachedFilesMaintainer = new CachedFilesMaintainer(cachedFileReferences, cachedDownloads, Duration.ofMinutes(1));
     }
 
     @Test
-    void require_old_files_to_be_deleted() {
+    void require_old_files_to_be_deleted() throws IOException {
         runMaintainerAndAssertFiles(0, 0);
 
-        clock.advance(Duration.ofSeconds(55));
-        // Create file references and downloads
-        createFiles();
+        File fileReference = writeFile(cachedFileReferences, "fileReference");
+        File download = writeFile(cachedDownloads, "download");
+        runMaintainerAndAssertFiles(1, 1);
 
-        runMaintainerAndAssertFiles(4, 4);
+        updateLastModifiedTimeStamp(fileReference, Instant.now().minus(Duration.ofMinutes(10)));
+        runMaintainerAndAssertFiles(0, 1);
 
-        clock.advance(Duration.ofMinutes(1));
-        runMaintainerAndAssertFiles(3, 3);
+        updateLastModifiedTimeStamp(download, Instant.now().minus(Duration.ofMinutes(10)));
+        runMaintainerAndAssertFiles(0, 0);
+    }
 
-        clock.advance(Duration.ofMinutes(100));
-        runMaintainerAndAssertFiles(numberToAlwaysKeep, numberToAlwaysKeep);
+    private void updateLastModifiedTimeStamp(File file, Instant instant) {
+        if (!file.setLastModified(instant.toEpochMilli())) {
+            throw new RuntimeException("Could not set last modified timestamp for '" + file.getAbsolutePath() + "'");
+        }
     }
 
     private void runMaintainerAndAssertFiles(int fileReferenceCount, int downloadCount) {
@@ -71,10 +65,10 @@ public class CachedFilesMaintainerTest {
         assertEquals(downloadCount, downloads.length);
     }
 
-    private void writeFileAndSetLastAccessedTime(File directory, String filename) throws IOException {
+    private File writeFile(File directory, String filename) throws IOException {
         File file = new File(directory, filename);
         IOUtils.writeFile(file, filename, false);
-        Files.setAttribute(file.toPath(), "lastAccessTime", FileTime.from(clock.instant()));
+        return file;
     }
 
     private static File newFolder(File root, String... subDirs) throws IOException {
@@ -86,16 +80,4 @@ public class CachedFilesMaintainerTest {
         return result;
     }
 
-    private void createFiles() {
-        IntStream.of(0,1,2,3).forEach(i -> {
-            try {
-                writeFileAndSetLastAccessedTime(cachedFileReferences, "fileReference" + i);
-                writeFileAndSetLastAccessedTime(cachedDownloads, "download" + i);
-                clock.advance(Duration.ofMinutes(1));
-            } catch (IOException e) {
-                throw new UncheckedIOException(e);
-            }
-        });
-    }
-
 }
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/ApplicationRepository.java b/configserver/src/main/java/com/yahoo/vespa/config/server/ApplicationRepository.java
index f832c504526..2a15f724b29 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/ApplicationRepository.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/ApplicationRepository.java
@@ -4,9 +4,9 @@ package com.yahoo.vespa.config.server;
 import ai.vespa.http.DomainName;
 import ai.vespa.http.HttpURL;
 import ai.vespa.http.HttpURL.Query;
+import com.yahoo.component.annotation.Inject;
 import com.yahoo.cloud.config.ConfigserverConfig;
 import com.yahoo.component.Version;
-import com.yahoo.component.annotation.Inject;
 import com.yahoo.config.FileReference;
 import com.yahoo.config.application.api.ApplicationFile;
 import com.yahoo.config.application.api.ApplicationMetaData;
@@ -83,18 +83,20 @@ import com.yahoo.vespa.curator.Curator;
 import com.yahoo.vespa.curator.stats.LockStats;
 import com.yahoo.vespa.curator.stats.ThreadLockStats;
 import com.yahoo.vespa.defaults.Defaults;
-import com.yahoo.vespa.filedistribution.maintenance.FileDistributionCleanup;
 import com.yahoo.vespa.flags.FlagSource;
 import com.yahoo.vespa.flags.InMemoryFlagSource;
 import com.yahoo.vespa.orchestrator.Orchestrator;
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.UncheckedIOException;
 import java.nio.file.Files;
+import java.nio.file.attribute.BasicFileAttributes;
 import java.time.Clock;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.Collection;
+import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -114,9 +116,11 @@ import static com.yahoo.config.model.api.container.ContainerServiceType.LOGSERVE
 import static com.yahoo.vespa.config.server.application.ConfigConvergenceChecker.ServiceListResponse;
 import static com.yahoo.vespa.config.server.application.ConfigConvergenceChecker.ServiceResponse;
 import static com.yahoo.vespa.config.server.filedistribution.FileDistributionUtil.fileReferenceExistsOnDisk;
+import static com.yahoo.vespa.config.server.filedistribution.FileDistributionUtil.getFileReferencesOnDisk;
 import static com.yahoo.vespa.config.server.tenant.TenantRepository.HOSTED_VESPA_TENANT;
 import static com.yahoo.vespa.curator.Curator.CompletionWaiter;
 import static com.yahoo.yolean.Exceptions.uncheck;
+import static java.nio.file.Files.readAttributes;
 
 /**
  * The API for managing applications.
@@ -586,11 +590,30 @@ public class ApplicationRepository implements com.yahoo.config.provision.Deploye
         return fileDistributionStatus.status(getApplication(applicationId), timeout);
     }
 
-    public void deleteUnusedFileDistributionReferences(File fileReferencesPath, Duration keepFileReferencesDuration) {
-        new FileDistributionCleanup(clock).deleteUnusedFileReferences(fileReferencesPath, keepFileReferencesDuration, getFileReferencesInUse());
+    public List<String> deleteUnusedFileDistributionReferences(File fileReferencesPath,
+                                                               Duration keepFileReferencesDuration,
+                                                               int numberToAlwaysKeep) {
+        log.log(Level.FINE, () -> "Keep unused file references for " + keepFileReferencesDuration);
+        if (!fileReferencesPath.isDirectory()) throw new RuntimeException(fileReferencesPath + " is not a directory");
+
+        Set<String> fileReferencesInUse = getFileReferencesInUse();
+        log.log(Level.FINE, () -> "File references in use : " + fileReferencesInUse);
+
+        List<String> candidates = sortedUnusedFileReferences(fileReferencesPath, fileReferencesInUse, keepFileReferencesDuration);
+        // Do not delete the newest ones
+        List<String> fileReferencesToDelete = candidates.subList(0, Math.max(0, candidates.size() - numberToAlwaysKeep));
+        if (fileReferencesToDelete.size() > 0) {
+            log.log(Level.FINE, () -> "Will delete file references not in use: " + fileReferencesToDelete);
+            fileReferencesToDelete.forEach(fileReference -> {
+                File file = new File(fileReferencesPath, fileReference);
+                if ( ! IOUtils.recursiveDeleteDir(file))
+                    log.log(Level.WARNING, "Could not delete " + file.getAbsolutePath());
+            });
+        }
+        return fileReferencesToDelete;
     }
 
-    Set<String> getFileReferencesInUse() {
+    private Set<String> getFileReferencesInUse() {
         Set<String> fileReferencesInUse = new HashSet<>();
         for (var applicationId : listApplications()) {
             Application app = getApplication(applicationId);
@@ -601,6 +624,18 @@ public class ApplicationRepository implements com.yahoo.config.provision.Deploye
         return fileReferencesInUse;
     }
 
+    private List<String> sortedUnusedFileReferences(File fileReferencesPath, Set<String> fileReferencesInUse, Duration keepFileReferences) {
+        Set<String> fileReferencesOnDisk = getFileReferencesOnDisk(fileReferencesPath);
+        log.log(Level.FINE, () -> "File references on disk (in " + fileReferencesPath + "): " + fileReferencesOnDisk);
+        Instant instant = clock.instant().minus(keepFileReferences);
+        return fileReferencesOnDisk
+                .stream()
+                .filter(fileReference -> ! fileReferencesInUse.contains(fileReference))
+                .filter(fileReference -> isLastFileAccessBefore(new File(fileReferencesPath, fileReference), instant))
+                .sorted(Comparator.comparing(a -> lastAccessed(new File(fileReferencesPath, a))))
+                .collect(Collectors.toList());
+    }
+
     public Set<FileReference> getFileReferences(ApplicationId applicationId) {
         return getOptionalApplication(applicationId).map(app -> app.getModel().fileReferences()).orElse(Set.of());
     }
@@ -651,6 +686,20 @@ public class ApplicationRepository implements com.yahoo.config.provision.Deploye
                 .collect(Collectors.toList());
     }
 
+    private boolean isLastFileAccessBefore(File fileReference, Instant instant) {
+        return lastAccessed(fileReference).isBefore(instant);
+    }
+
+    private Instant lastAccessed(File fileReference) {
+        BasicFileAttributes fileAttributes;
+        try {
+            fileAttributes = readAttributes(fileReference.toPath(), BasicFileAttributes.class);
+            return fileAttributes.lastAccessTime().toInstant();
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
+
     public Optional<String> getApplicationPackageReference(ApplicationId applicationId) {
         Optional<String> applicationPackage = Optional.empty();
         Optional<Session> session = getActiveSession(applicationId);
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/filedistribution/FileDistributionUtil.java b/configserver/src/main/java/com/yahoo/vespa/config/server/filedistribution/FileDistributionUtil.java
index c1de9b4e5f6..a1ddad7bfd4 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/filedistribution/FileDistributionUtil.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/filedistribution/FileDistributionUtil.java
@@ -5,9 +5,12 @@ import com.yahoo.cloud.config.ConfigserverConfig;
 import com.yahoo.config.FileReference;
 import com.yahoo.net.HostName;
 import com.yahoo.vespa.config.server.ConfigServerSpec;
-import com.yahoo.vespa.filedistribution.maintenance.FileDistributionCleanup;
+
 import java.io.File;
+import java.util.Arrays;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 import java.util.stream.Collectors;
 
 /**
@@ -18,6 +21,17 @@ import java.util.stream.Collectors;
  */
 public class FileDistributionUtil {
 
+    /**
+     * Returns all files in the given directory, non-recursive.
+     */
+    public static Set<String> getFileReferencesOnDisk(File directory) {
+        Set<String> fileReferencesOnDisk = new HashSet<>();
+        File[] filesOnDisk = directory.listFiles();
+        if (filesOnDisk != null)
+            fileReferencesOnDisk.addAll(Arrays.stream(filesOnDisk).map(File::getName).collect(Collectors.toSet()));
+        return fileReferencesOnDisk;
+    }
+
     public static List<String> getOtherConfigServersInCluster(ConfigserverConfig configserverConfig) {
         return ConfigServerSpec.fromConfig(configserverConfig)
                                .stream()
@@ -27,8 +41,7 @@ public class FileDistributionUtil {
     }
 
     public static boolean fileReferenceExistsOnDisk(File downloadDirectory, FileReference applicationPackageReference) {
-        return FileDistributionCleanup.getFileReferencesOnDisk(downloadDirectory.toPath())
-                                      .anyMatch(fileReference -> fileReference.equals(applicationPackageReference.value()));
+        return getFileReferencesOnDisk(downloadDirectory).contains(applicationPackageReference.value());
     }
 
 }
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/maintenance/FileDistributionMaintainer.java b/configserver/src/main/java/com/yahoo/vespa/config/server/maintenance/FileDistributionMaintainer.java
index 5542d24253b..f6aee416c9c 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/maintenance/FileDistributionMaintainer.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/maintenance/FileDistributionMaintainer.java
@@ -20,6 +20,8 @@ import java.time.Duration;
  */
 public class FileDistributionMaintainer extends ConfigServerMaintainer {
 
+    private static final int numberToAlwaysKeep = 20;
+
     private final ApplicationRepository applicationRepository;
     private final File fileReferencesDir;
     private final Duration maxUnusedFileReferenceAge;
@@ -37,7 +39,7 @@ public class FileDistributionMaintainer extends ConfigServerMaintainer {
 
     @Override
     protected double maintain() {
-        applicationRepository.deleteUnusedFileDistributionReferences(fileReferencesDir, maxUnusedFileReferenceAge);
+        applicationRepository.deleteUnusedFileDistributionReferences(fileReferencesDir, maxUnusedFileReferenceAge, numberToAlwaysKeep);
         return 1.0;
     }
 
diff --git a/configserver/src/test/java/com/yahoo/vespa/config/server/ApplicationRepositoryTest.java b/configserver/src/test/java/com/yahoo/vespa/config/server/ApplicationRepositoryTest.java
index 4f7be104b9c..99487230c5d 100644
--- a/configserver/src/test/java/com/yahoo/vespa/config/server/ApplicationRepositoryTest.java
+++ b/configserver/src/test/java/com/yahoo/vespa/config/server/ApplicationRepositoryTest.java
@@ -49,7 +49,6 @@ import com.yahoo.vespa.config.server.tenant.TestTenantRepository;
 import com.yahoo.vespa.config.util.ConfigUtils;
 import com.yahoo.vespa.curator.Curator;
 import com.yahoo.vespa.curator.mock.MockCurator;
-import com.yahoo.vespa.filedistribution.maintenance.FileDistributionCleanup;
 import com.yahoo.vespa.flags.InMemoryFlagSource;
 import com.yahoo.vespa.model.VespaModelFactory;
 import org.junit.Before;
@@ -294,10 +293,9 @@ public class ApplicationRepositoryTest {
         PrepareParams prepareParams = new PrepareParams.Builder().applicationId(applicationId()).ignoreValidationErrors(true).build();
         deployApp(new File("src/test/apps/app"), prepareParams);
 
-        List<String> toBeDeleted = new FileDistributionCleanup(clock).deleteUnusedFileReferences(fileReferencesDir,
-                                                                                                 keepFileReferencesDuration,
-                                                                                                 2,
-                                                                                                 applicationRepository.getFileReferencesInUse());
+        List<String> toBeDeleted = applicationRepository.deleteUnusedFileDistributionReferences(fileReferencesDir,
+                                                                                                keepFileReferencesDuration,
+                                                                                                2);
         Collections.sort(toBeDeleted);
         assertEquals(List.of("bar0", "foo"), toBeDeleted);
         // bar0 and foo are the only ones that will be deleted (keeps 2 newest no matter how old they are)
diff --git a/filedistribution/src/main/java/com/yahoo/vespa/filedistribution/maintenance/FileDistributionCleanup.java b/filedistribution/src/main/java/com/yahoo/vespa/filedistribution/maintenance/FileDistributionCleanup.java
deleted file mode 100644
index 9c04e7253bb..00000000000
--- a/filedistribution/src/main/java/com/yahoo/vespa/filedistribution/maintenance/FileDistributionCleanup.java
+++ /dev/null
@@ -1,107 +0,0 @@
-// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-package com.yahoo.vespa.filedistribution.maintenance;
-
-import com.yahoo.io.IOUtils;
-import java.io.File;
-import java.io.IOException;
-import java.io.UncheckedIOException;
-import java.nio.file.Files;
-import java.nio.file.Path;
-import java.nio.file.attribute.BasicFileAttributes;
-import java.time.Clock;
-import java.time.Duration;
-import java.time.Instant;
-import java.util.ArrayList;
-import java.util.Comparator;
-import java.util.List;
-import java.util.Set;
-import java.util.concurrent.atomic.AtomicInteger;
-import java.util.logging.Level;
-import java.util.logging.Logger;
-import java.util.stream.Stream;
-
-import static java.nio.file.Files.readAttributes;
-
-/**
- * Removes file references not used since a configured time, but always keeps a certain number of file references
- * even when they are unused (unused is based on last access time for the file).
- *
- * @author hmusum
- */
-public class FileDistributionCleanup {
-
-    private static final Logger log = Logger.getLogger(FileDistributionCleanup.class.getName());
-    private static final int numberToAlwaysKeep = 20;
-
-    private final Clock clock;
-
-    public FileDistributionCleanup(Clock clock) {
-        this.clock = clock;
-    }
-
-    public List<String> deleteUnusedFileReferences(File fileReferencesPath,
-                                                   Duration keepFileReferencesDuration,
-                                                   Set<String> fileReferencesInUse) {
-        return deleteUnusedFileReferences(fileReferencesPath,
-                                          keepFileReferencesDuration,
-                                          numberToAlwaysKeep,
-                                          fileReferencesInUse);
-    }
-
-    public List<String> deleteUnusedFileReferences(File fileReferencesDir,
-                                                   Duration keepFileReferencesDuration,
-                                                   int numberToAlwaysKeep,
-                                                   Set<String> fileReferencesInUse) {
-        if (!fileReferencesDir.isDirectory()) throw new RuntimeException(fileReferencesDir + " is not a directory");
-
-        log.log(Level.FINE, () -> "Keep unused file references for " + keepFileReferencesDuration +
-                ", file references in use : " + fileReferencesInUse);
-        List<String> fileReferencesDeleted = new ArrayList<>();
-        Path fileReferencesPath = fileReferencesDir.toPath();
-        try (Stream<String> candidates = sortedUnusedFileReferences(fileReferencesPath, fileReferencesInUse, keepFileReferencesDuration)) {
-            final AtomicInteger i = new AtomicInteger(0);
-            candidates.forEach(fileReference -> {
-                // Do not delete the newest ones
-                if (i.incrementAndGet() > numberToAlwaysKeep) {
-                    fileReferencesDeleted.add(fileReference);
-                    File file = new File(fileReferencesDir, fileReference);
-                    if (!IOUtils.recursiveDeleteDir(file))
-                        log.log(Level.WARNING, "Could not delete " + file.getAbsolutePath());
-                }
-            });
-        }
-        return fileReferencesDeleted;
-    }
-
-    // Sorted, newest first
-    private Stream<String> sortedUnusedFileReferences(Path fileReferencesPath, Set<String> fileReferencesInUse, Duration keepFileReferences) {
-        Instant instant = clock.instant().minus(keepFileReferences);
-        return getFileReferencesOnDisk(fileReferencesPath)
-                .filter(fileReference -> !fileReferencesInUse.contains(fileReference))
-                .filter(fileReference -> isLastFileAccessBefore(new File(fileReferencesPath.toFile(), fileReference), instant))
-                .sorted(Comparator.comparing(a -> lastAccessed(new File(fileReferencesPath.toFile(), (String) a))).reversed());
-    }
-
-    private boolean isLastFileAccessBefore(File fileReference, Instant instant) {
-        return lastAccessed(fileReference).isBefore(instant);
-    }
-
-    private Instant lastAccessed(File fileReference) {
-        BasicFileAttributes fileAttributes;
-        try {
-            fileAttributes = readAttributes(fileReference.toPath(), BasicFileAttributes.class);
-            return fileAttributes.lastAccessTime().toInstant();
-        } catch (IOException e) {
-            throw new UncheckedIOException(e);
-        }
-    }
-
-    public static Stream<String> getFileReferencesOnDisk(Path directory) {
-        try {
-            return Files.list(directory).map(path -> path.toFile().getName());
-        } catch (IOException e) {
-            throw new UncheckedIOException(e);
-        }
-    }
-
-}