Backfill missing attachment hashes.

app/src/androidTest/java/org/thoughtcrime/securesms/database/AttachmentTableTest_deduping.kt

@@ -11,6 +11,8 @@ import org.junit.Assert.assertTrue
 import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
+import org.signal.core.util.Base64
+import org.signal.core.util.update
 import org.thoughtcrime.securesms.attachments.AttachmentId
 import org.thoughtcrime.securesms.attachments.PointerAttachment
 import org.thoughtcrime.securesms.database.AttachmentTable.TransformProperties
@@ -37,6 +39,7 @@ class AttachmentTableTest_deduping {
   companion object {
     val DATA_A = byteArrayOf(1, 2, 3)
     val DATA_A_COMPRESSED = byteArrayOf(4, 5, 6)
+    val DATA_A_HASH = byteArrayOf(1, 1, 1)
 
     val DATA_B = byteArrayOf(7, 8, 9)
   }
@@ -339,6 +342,25 @@ class AttachmentTableTest_deduping {
       assertSkipTransform(id2, false)
       assertDoesNotHaveRemoteFields(id2)
     }
+
+    // Make sure that files marked as unhashable are all updated together
+    test {
+      val id1 = insertWithData(DATA_A)
+      val id2 = insertWithData(DATA_A)
+      upload(id1)
+      upload(id2)
+      clearHashes(id1)
+      clearHashes(id2)
+
+      val file = dataFile(id1)
+      SignalDatabase.attachments.markDataFileAsUnhashable(file)
+
+      assertDataFilesAreTheSame(id1, id2)
+      assertDataHashEndMatches(id1, id2)
+
+      val dataFileInfo = SignalDatabase.attachments.getDataFileInfo(id1)!!
+      assertTrue(dataFileInfo.hashEnd!!.startsWith("UNHASHABLE-"))
+    }
   }
 
   /**
@@ -412,6 +434,131 @@ class AttachmentTableTest_deduping {
     }
   }
 
+  /**
+   * Suite of tests around the migration where we hash all of the attachments and potentially dedupe them.
+   */
+  @Test
+  fun migration() {
+    // Verifying that getUnhashedDataFile only returns if there's actually missing hashes
+    test {
+      val id = insertWithData(DATA_A)
+      upload(id)
+      assertNull(SignalDatabase.attachments.getUnhashedDataFile())
+    }
+
+    // Verifying that getUnhashedDataFile finds the missing hash
+    test {
+      val id = insertWithData(DATA_A)
+      upload(id)
+      clearHashes(id)
+      assertNotNull(SignalDatabase.attachments.getUnhashedDataFile())
+    }
+
+    // Verifying that getUnhashedDataFile doesn't return if the file isn't done downloading
+    test {
+      val id = insertWithData(DATA_A)
+      upload(id)
+      setTransferState(id, AttachmentTable.TRANSFER_PROGRESS_PENDING)
+      clearHashes(id)
+      assertNull(SignalDatabase.attachments.getUnhashedDataFile())
+    }
+
+    // If two attachments share the same file, when we backfill the hash, make sure both get their hashes set
+    test {
+      val id1 = insertWithData(DATA_A)
+      val id2 = insertWithData(DATA_A)
+      upload(id1)
+      upload(id2)
+
+      clearHashes(id1)
+      clearHashes(id2)
+
+      val file = dataFile(id1)
+      SignalDatabase.attachments.setHashForDataFile(file, DATA_A_HASH)
+
+      assertDataHashEnd(id1, DATA_A_HASH)
+      assertDataHashEndMatches(id1, id2)
+    }
+
+    // Creates a situation where two different attachments have the same data but wrote to different files, and verifies the migration dedupes it
+    test {
+      val id1 = insertWithData(DATA_A)
+      upload(id1)
+      clearHashes(id1)
+
+      val id2 = insertWithData(DATA_A)
+      upload(id2)
+      clearHashes(id2)
+
+      assertDataFilesAreDifferent(id1, id2)
+
+      val file1 = dataFile(id1)
+      SignalDatabase.attachments.setHashForDataFile(file1, DATA_A_HASH)
+
+      assertDataHashEnd(id1, DATA_A_HASH)
+      assertDataFilesAreDifferent(id1, id2)
+
+      val file2 = dataFile(id2)
+      SignalDatabase.attachments.setHashForDataFile(file2, DATA_A_HASH)
+
+      assertDataFilesAreTheSame(id1, id2)
+      assertDataHashEndMatches(id1, id2)
+      assertFalse(file2.exists())
+    }
+
+    // We've got three files now with the same data, with two of them sharing a file. We want to make sure *both* entries that share the same file get deduped.
+    test {
+      val id1 = insertWithData(DATA_A)
+      upload(id1)
+      clearHashes(id1)
+
+      val id2 = insertWithData(DATA_A)
+      val id3 = insertWithData(DATA_A)
+      upload(id2)
+      upload(id3)
+      clearHashes(id2)
+      clearHashes(id3)
+
+      assertDataFilesAreDifferent(id1, id2)
+      assertDataFilesAreTheSame(id2, id3)
+
+      val file1 = dataFile(id1)
+      SignalDatabase.attachments.setHashForDataFile(file1, DATA_A_HASH)
+      assertDataHashEnd(id1, DATA_A_HASH)
+
+      val file2 = dataFile(id2)
+      SignalDatabase.attachments.setHashForDataFile(file2, DATA_A_HASH)
+
+      assertDataFilesAreTheSame(id1, id2)
+      assertDataHashEndMatches(id1, id2)
+      assertDataHashEndMatches(id2, id3)
+      assertFalse(file2.exists())
+    }
+
+    // We don't want to mess with files that are still downloading, so this makes sure that even if data matches, we don't dedupe and don't delete the file
+    test {
+      val id1 = insertWithData(DATA_A)
+      upload(id1)
+      clearHashes(id1)
+
+      val id2 = insertWithData(DATA_A)
+      // *not* uploaded
+      clearHashes(id2)
+
+      assertDataFilesAreDifferent(id1, id2)
+
+      val file1 = dataFile(id1)
+      SignalDatabase.attachments.setHashForDataFile(file1, DATA_A_HASH)
+      assertDataHashEnd(id1, DATA_A_HASH)
+
+      val file2 = dataFile(id2)
+      SignalDatabase.attachments.setHashForDataFile(file2, DATA_A_HASH)
+
+      assertDataFilesAreDifferent(id1, id2)
+      assertTrue(file2.exists())
+    }
+  }
+
   private class TestContext {
     fun insertWithData(data: ByteArray, transformProperties: TransformProperties = TransformProperties.empty()): AttachmentId {
       val uri = BlobProvider.getInstance().forData(data).createForSingleSessionInMemory()
@@ -472,6 +619,22 @@ class AttachmentTableTest_deduping {
       return SignalDatabase.attachments.getDataFileInfo(attachmentId)!!.file
     }
 
+    fun setTransferState(attachmentId: AttachmentId, transferState: Int) {
+      // messageId doesn't actually matter -- that's for notifying listeners
+      SignalDatabase.attachments.setTransferState(messageId = -1, attachmentId = attachmentId, transferState = transferState)
+    }
+
+    fun clearHashes(id: AttachmentId) {
+      SignalDatabase.attachments.writableDatabase
+        .update(AttachmentTable.TABLE_NAME)
+        .values(
+          AttachmentTable.DATA_HASH_START to null,
+          AttachmentTable.DATA_HASH_END to null
+        )
+        .where("${AttachmentTable.ID} = ?", id)
+        .run()
+    }
+
     fun assertDeleted(attachmentId: AttachmentId) {
       assertNull("$attachmentId exists, but it shouldn't!", SignalDatabase.attachments.getAttachment(attachmentId))
     }
@@ -525,6 +688,11 @@ class AttachmentTableTest_deduping {
       assertEquals("DATA_HASH_END's did not match!", lhsInfo.hashEnd, rhsInfo.hashEnd)
     }
 
+    fun assertDataHashEnd(id: AttachmentId, byteArray: ByteArray) {
+      val dataFileInfo = SignalDatabase.attachments.getDataFileInfo(id)!!
+      assertArrayEquals(byteArray, Base64.decode(dataFileInfo.hashEnd!!))
+    }
+
     fun assertRemoteFieldsMatch(lhs: AttachmentId, rhs: AttachmentId) {
       val lhsAttachment = SignalDatabase.attachments.getAttachment(lhs)!!
       val rhsAttachment = SignalDatabase.attachments.getAttachment(rhs)!!

app/src/main/java/org/thoughtcrime/securesms/database/AttachmentTable.kt

@@ -94,6 +94,7 @@ import java.security.MessageDigest
 import java.security.NoSuchAlgorithmException
 import java.util.LinkedList
 import java.util.Optional
+import java.util.UUID
 import kotlin.time.Duration.Companion.days
 
 class AttachmentTable(
@@ -255,6 +256,80 @@ class AttachmentTable(
     } ?: throw IOException("No stream for: $attachmentId")
   }
 
+  /**
+   * Returns a [File] for an attachment that has no [DATA_HASH_END] and is in the [TRANSFER_PROGRESS_DONE] state, if present.
+   */
+  fun getUnhashedDataFile(): Pair<File, AttachmentId>? {
+    return readableDatabase
+      .select(ID, DATA_FILE)
+      .from(TABLE_NAME)
+      .where("$DATA_FILE NOT NULL AND $DATA_HASH_END IS NULL AND $TRANSFER_STATE = $TRANSFER_PROGRESS_DONE")
+      .orderBy("$ID DESC")
+      .limit(1)
+      .run()
+      .readToSingleObject {
+        File(it.requireNonNullString(DATA_FILE)) to AttachmentId(it.requireLong(ID))
+      }
+  }
+
+  /**
+   * Sets the [DATA_HASH_END] for a given file. This is used to backfill the hash for attachments that were created before we started hashing them.
+   * As a result, this will _not_ update the hashes on files that are not fully uploaded.
+   */
+  fun setHashForDataFile(file: File, hash: ByteArray) {
+    writableDatabase.withinTransaction { db ->
+      val hashEnd = Base64.encodeWithPadding(hash)
+
+      val (existingFile: String?, existingSize: Long?, existingRandom: ByteArray?) = db.select(DATA_FILE, DATA_SIZE, DATA_RANDOM)
+        .from(TABLE_NAME)
+        .where("$DATA_HASH_END = ? AND $TRANSFER_STATE = $TRANSFER_PROGRESS_DONE AND $DATA_FILE NOT NULL AND $DATA_FILE != ?", hashEnd, file.absolutePath)
+        .limit(1)
+        .run()
+        .readToSingleObject {
+          Triple(
+            it.requireString(DATA_FILE),
+            it.requireLong(DATA_SIZE),
+            it.requireBlob(DATA_RANDOM)
+          )
+        } ?: Triple(null, null, null)
+
+      if (existingFile != null) {
+        Log.i(TAG, "[setHashForDataFile] Found that a different file has the same HASH_END. Using that one instead. Pre-existing file: $existingFile", true)
+
+        val updateCount = writableDatabase
+          .update(TABLE_NAME)
+          .values(
+            DATA_FILE to existingFile,
+            DATA_HASH_END to hashEnd,
+            DATA_SIZE to existingSize,
+            DATA_RANDOM to existingRandom
+          )
+          .where("$DATA_FILE = ? AND $DATA_HASH_END IS NULL AND $TRANSFER_STATE = $TRANSFER_PROGRESS_DONE", file.absolutePath)
+          .run()
+
+        Log.i(TAG, "[setHashForDataFile] Deduped $updateCount attachments.", true)
+
+        val oldFileInUse = db.exists(TABLE_NAME).where("$DATA_FILE = ?", file.absolutePath).run()
+        if (oldFileInUse) {
+          Log.i(TAG, "[setHashForDataFile] Old file is still in use by some in-progress attachment.", true)
+        } else {
+          Log.i(TAG, "[setHashForDataFile] Deleting unused file: $file")
+          if (!file.delete()) {
+            Log.w(TAG, "Failed to delete duped file!")
+          }
+        }
+      } else {
+        val updateCount = writableDatabase
+          .update(TABLE_NAME)
+          .values(DATA_HASH_END to Base64.encodeWithPadding(hash))
+          .where("$DATA_FILE = ? AND $TRANSFER_STATE = $TRANSFER_PROGRESS_DONE", file.absolutePath)
+          .run()
+
+        Log.i(TAG, "[setHashForDataFile] Updated the HASH_END for $updateCount rows using file ${file.absolutePath}")
+      }
+    }
+  }
+
   fun getAttachment(attachmentId: AttachmentId): DatabaseAttachment? {
     return readableDatabase
       .select(*PROJECTION)
@@ -482,6 +557,34 @@ class AttachmentTable(
     return onDiskButNotInDatabase.size
   }
 
+  /**
+   * Removes all references to the provided [DATA_FILE] from all attachments.
+   * Only do this if the file is known to not exist or has some other critical problem!
+   */
+  fun clearUsagesOfDataFile(file: File) {
+    val updateCount = writableDatabase
+      .update(TABLE_NAME)
+      .values(DATA_FILE to null)
+      .where("$DATA_FILE = ?", file.absolutePath)
+      .run()
+
+    Log.i(TAG, "[clearUsagesOfFile] Cleared $updateCount usages of $file", true)
+  }
+
+  /**
+   * Indicates that, for whatever reason, a hash could not be calculated for the file in question.
+   * We put in a "bad hash" that will never match anything else so that we don't attempt to backfill it in the future.
+   */
+  fun markDataFileAsUnhashable(file: File) {
+    val updateCount = writableDatabase
+      .update(TABLE_NAME)
+      .values(DATA_HASH_END to "UNHASHABLE-${UUID.randomUUID()}")
+      .where("$DATA_FILE = ? AND $DATA_HASH_END IS NULL AND $TRANSFER_STATE = $TRANSFER_PROGRESS_DONE", file.absolutePath)
+      .run()
+
+    Log.i(TAG, "[markDataFileAsUnhashable] Marked $updateCount attachments as unhashable with file: ${file.absolutePath}", true)
+  }
+
   fun deleteAllAttachments() {
     Log.d(TAG, "[deleteAllAttachments]")
 
@@ -1610,6 +1713,11 @@ class AttachmentTable(
         return existing.copy(sentMediaQuality = sentMediaQuality.code)
       }
 
+      @JvmStatic
+      fun forSentMediaQuality(sentMediaQuality: Int): TransformProperties {
+        return TransformProperties(sentMediaQuality = sentMediaQuality)
+      }
+
       @JvmStatic
       fun parse(serialized: String?): TransformProperties {
         return if (serialized == null) {

app/src/main/java/org/thoughtcrime/securesms/jobmanager/JobExtensions.kt

@@ -0,0 +1,14 @@
+/*
+ * Copyright 2024 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.jobmanager
+
+import org.thoughtcrime.securesms.jobmanager.impl.BackoffUtil
+import org.thoughtcrime.securesms.util.FeatureFlags
+
+/**
+ * Helper to calculate the default backoff interval for a [Job] given it's run attempt count.
+ */
+fun Job.defaultBackoffInterval(): Long = BackoffUtil.exponentialBackoff(runAttempt + 1, FeatureFlags.getDefaultMaxBackoff())

app/src/main/java/org/thoughtcrime/securesms/jobs/AttachmentHashBackfillJob.kt

@@ -0,0 +1,112 @@
+/*
+ * Copyright 2024 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.jobs
+
+import org.signal.core.util.ThreadUtil
+import org.signal.core.util.drain
+import org.signal.core.util.logging.Log
+import org.thoughtcrime.securesms.attachments.AttachmentId
+import org.thoughtcrime.securesms.database.SignalDatabase
+import org.thoughtcrime.securesms.dependencies.ApplicationDependencies
+import org.thoughtcrime.securesms.jobmanager.Job
+import org.thoughtcrime.securesms.jobmanager.defaultBackoffInterval
+import java.io.File
+import java.io.FileNotFoundException
+import java.io.IOException
+import java.security.DigestInputStream
+import java.security.MessageDigest
+
+/**
+ * This job backfills hashes for attachments that were sent before we started hashing them.
+ * In order to avoid hammering the device with hash calculations and disk I/O, this job will
+ * calculate the hash for a single attachment and then reschedule itself to run again if necessary.
+ */
+class AttachmentHashBackfillJob private constructor(parameters: Parameters) : Job(parameters) {
+
+  companion object {
+    val TAG = Log.tag(AttachmentHashBackfillJob::class.java)
+
+    const val KEY = "AttachmentHashBackfillJob"
+  }
+
+  private var activeFile: File? = null
+
+  constructor() : this(
+    Parameters.Builder()
+      .setQueue(KEY)
+      .setMaxInstancesForFactory(2)
+      .setLifespan(Parameters.IMMORTAL)
+      .setMaxAttempts(10)
+      .build()
+  )
+
+  override fun serialize() = null
+
+  override fun getFactoryKey() = KEY
+
+  override fun run(): Result {
+    val (file: File?, attachmentId: AttachmentId?) = SignalDatabase.attachments.getUnhashedDataFile() ?: (null to null)
+    if (file == null || attachmentId == null) {
+      Log.i(TAG, "No more unhashed files! Task complete.")
+      return Result.success()
+    }
+
+    activeFile = file
+
+    if (!file.exists()) {
+      Log.w(TAG, "File does not exist! Clearing all usages.", true)
+      SignalDatabase.attachments.clearUsagesOfDataFile(file)
+      ApplicationDependencies.getJobManager().add(AttachmentHashBackfillJob())
+      return Result.success()
+    }
+
+    try {
+      val inputStream = SignalDatabase.attachments.getAttachmentStream(attachmentId, 0)
+      val messageDigest = MessageDigest.getInstance("SHA-256")
+
+      DigestInputStream(inputStream, messageDigest).use {
+        it.drain()
+      }
+
+      val hash = messageDigest.digest()
+
+      SignalDatabase.attachments.setHashForDataFile(file, hash)
+    } catch (e: FileNotFoundException) {
+      Log.w(TAG, "File could not be found! Clearing all usages.", true)
+      SignalDatabase.attachments.clearUsagesOfDataFile(file)
+    } catch (e: IOException) {
+      Log.e(TAG, "Error hashing attachment. Retrying.", e)
+
+      if (e.cause is FileNotFoundException) {
+        Log.w(TAG, "Underlying cause was a FileNotFoundException. Clearing all usages.", true)
+        SignalDatabase.attachments.clearUsagesOfDataFile(file)
+      } else {
+        return Result.retry(defaultBackoffInterval())
+      }
+    }
+
+    // Sleep just so we don't hammer the device with hash calculations and disk I/O
+    ThreadUtil.sleep(1000)
+
+    ApplicationDependencies.getJobManager().add(AttachmentHashBackfillJob())
+    return Result.success()
+  }
+
+  override fun onFailure() {
+    activeFile?.let { file ->
+      Log.w(TAG, "Failed to calculate hash, marking as unhashable: $file", true)
+      SignalDatabase.attachments.markDataFileAsUnhashable(file)
+    } ?: Log.w(TAG, "Job failed, but no active file is set!")
+
+    ApplicationDependencies.getJobManager().add(AttachmentHashBackfillJob())
+  }
+
+  class Factory : Job.Factory<AttachmentHashBackfillJob> {
+    override fun create(parameters: Parameters, serializedData: ByteArray?): AttachmentHashBackfillJob {
+      return AttachmentHashBackfillJob(parameters)
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/jobs/JobManagerFactories.java

@@ -40,6 +40,7 @@ import org.thoughtcrime.securesms.migrations.AccountConsistencyMigrationJob;
 import org.thoughtcrime.securesms.migrations.AccountRecordMigrationJob;
 import org.thoughtcrime.securesms.migrations.ApplyUnknownFieldsToSelfMigrationJob;
 import org.thoughtcrime.securesms.migrations.AttachmentCleanupMigrationJob;
+import org.thoughtcrime.securesms.migrations.AttachmentHashBackfillMigrationJob;
 import org.thoughtcrime.securesms.migrations.AttributesMigrationJob;
 import org.thoughtcrime.securesms.migrations.AvatarIdRemovalMigrationJob;
 import org.thoughtcrime.securesms.migrations.AvatarMigrationJob;
@@ -101,6 +102,7 @@ public final class JobManagerFactories {
       put(AttachmentCompressionJob.KEY,              new AttachmentCompressionJob.Factory());
       put(AttachmentCopyJob.KEY,                     new AttachmentCopyJob.Factory());
       put(AttachmentDownloadJob.KEY,                 new AttachmentDownloadJob.Factory());
+      put(AttachmentHashBackfillJob.KEY,             new AttachmentHashBackfillJob.Factory());
       put(AttachmentMarkUploadedJob.KEY,             new AttachmentMarkUploadedJob.Factory());
       put(AttachmentUploadJob.KEY,                   new AttachmentUploadJob.Factory());
       put(AutomaticSessionResetJob.KEY,              new AutomaticSessionResetJob.Factory());
@@ -225,6 +227,7 @@ public final class JobManagerFactories {
       put(AccountRecordMigrationJob.KEY,             new AccountRecordMigrationJob.Factory());
       put(ApplyUnknownFieldsToSelfMigrationJob.KEY,  new ApplyUnknownFieldsToSelfMigrationJob.Factory());
       put(AttachmentCleanupMigrationJob.KEY,         new AttachmentCleanupMigrationJob.Factory());
+      put(AttachmentHashBackfillMigrationJob.KEY,    new AttachmentHashBackfillMigrationJob.Factory());
       put(AttributesMigrationJob.KEY,                new AttributesMigrationJob.Factory());
       put(AvatarIdRemovalMigrationJob.KEY,           new AvatarIdRemovalMigrationJob.Factory());
       put(AvatarMigrationJob.KEY,                    new AvatarMigrationJob.Factory());

app/src/main/java/org/thoughtcrime/securesms/migrations/ApplicationMigrations.java

@@ -145,11 +145,12 @@ public class ApplicationMigrations {
     static final int STORAGE_LOCAL_UNKNOWNS_FIX    = 101;
     static final int PNP_LAUNCH                    = 102;
     static final int EMOJI_VERSION_10              = 103;
+    static final int ATTACHMENT_HASH_BACKFILL      = 104;
   }
 
-  public static final int CURRENT_VERSION = 103;
+  public static final int CURRENT_VERSION = 104;
 
-  /**
+ /**
    * This *must* be called after the {@link JobManager} has been instantiated, but *before* the call
    * to {@link JobManager#beginJobLoop()}. Otherwise, other non-migration jobs may have started
    * executing before we add the migration jobs.
@@ -662,6 +663,10 @@ public class ApplicationMigrations {
       jobs.put(Version.EMOJI_VERSION_10, new EmojiDownloadMigrationJob());
     }
 
+    if (lastSeenVersion < Version.ATTACHMENT_HASH_BACKFILL) {
+      jobs.put(Version.ATTACHMENT_HASH_BACKFILL, new AttachmentHashBackfillMigrationJob());
+    }
+
     return jobs;
   }
 

app/src/main/java/org/thoughtcrime/securesms/migrations/AttachmentHashBackfillMigrationJob.kt

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2024 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.migrations
+
+import org.signal.core.util.logging.Log
+import org.thoughtcrime.securesms.dependencies.ApplicationDependencies
+import org.thoughtcrime.securesms.jobmanager.Job
+import org.thoughtcrime.securesms.jobs.AttachmentHashBackfillJob
+import java.lang.Exception
+
+/**
+ * Kicks off the attachment hash backfill process by enqueueing a [AttachmentHashBackfillJob].
+ */
+internal class AttachmentHashBackfillMigrationJob(parameters: Parameters = Parameters.Builder().build()) : MigrationJob(parameters) {
+
+  companion object {
+    val TAG = Log.tag(AttachmentHashBackfillMigrationJob::class.java)
+    const val KEY = "AttachmentHashBackfillMigrationJob"
+  }
+
+  override fun getFactoryKey(): String = KEY
+
+  override fun isUiBlocking(): Boolean = false
+
+  override fun performMigration() {
+    ApplicationDependencies.getJobManager().add(AttachmentHashBackfillJob())
+  }
+
+  override fun shouldRetry(e: Exception): Boolean = false
+
+  class Factory : Job.Factory<AttachmentHashBackfillMigrationJob> {
+    override fun create(parameters: Parameters, serializedData: ByteArray?): AttachmentHashBackfillMigrationJob {
+      return AttachmentHashBackfillMigrationJob(parameters)
+    }
+  }
+}