SERVER-38179 Refactor RemoveSaver out of dbhelpers

11 files changed, 288 insertions, 181 deletions

diff --git a/src/mongo/db/dbhelpers.cpp b/src/mongo/db/dbhelpers.cpp
index d1b5b9518fa..6598b445dcc 100644
--- a/src/mongo/db/dbhelpers.cpp
+++ b/src/mongo/db/dbhelpers.cpp
@@ -34,9 +34,6 @@
 
 #include "mongo/db/dbhelpers.h"
 
-#include <boost/filesystem/operations.hpp>
-#include <fstream>
-
 #include "mongo/db/db_raii.h"
 #include "mongo/db/exec/working_set_common.h"
 #include "mongo/db/index/btree_access_method.h"
@@ -55,9 +52,6 @@
 #include "mongo/db/repl/repl_client_info.h"
 #include "mongo/db/repl/replication_coordinator.h"
 #include "mongo/db/service_context.h"
-#include "mongo/db/storage/data_protector.h"
-#include "mongo/db/storage/encryption_hooks.h"
-#include "mongo/db/storage/storage_options.h"
 #include "mongo/db/write_concern.h"
 #include "mongo/db/write_concern_options.h"
 #include "mongo/util/log.h"
@@ -67,11 +61,8 @@
 namespace mongo {
 
 using std::unique_ptr;
-using std::ios_base;
-using std::ofstream;
 using std::set;
 using std::string;
-using std::stringstream;
 
 /* fetch a single object from collection ns that matches query
    set your db SavedContext first
@@ -276,123 +267,4 @@ void Helpers::emptyCollection(OperationContext* opCtx, const NamespaceString& ns
     deleteObjects(opCtx, collection, nss, BSONObj(), false);
 }
 
-Helpers::RemoveSaver::RemoveSaver(const string& a, const string& b, const string& why) {
-    static int NUM = 0;
-
-    _root = storageGlobalParams.dbpath;
-    if (a.size())
-        _root /= a;
-    if (b.size())
-        _root /= b;
-    verify(a.size() || b.size());
-
-    _file = _root;
-
-    stringstream ss;
-    ss << why << "." << terseCurrentTime(false) << "." << NUM++ << ".bson";
-    _file /= ss.str();
-
-    auto encryptionHooks = EncryptionHooks::get(getGlobalServiceContext());
-    if (encryptionHooks->enabled()) {
-        _protector = encryptionHooks->getDataProtector();
-        _file += encryptionHooks->getProtectedPathSuffix();
-    }
-}
-
-Helpers::RemoveSaver::~RemoveSaver() {
-    if (_protector && _out) {
-        auto encryptionHooks = EncryptionHooks::get(getGlobalServiceContext());
-        invariant(encryptionHooks->enabled());
-
-        size_t protectedSizeMax = encryptionHooks->additionalBytesForProtectedBuffer();
-        std::unique_ptr<uint8_t[]> protectedBuffer(new uint8_t[protectedSizeMax]);
-
-        size_t resultLen;
-        Status status = _protector->finalize(protectedBuffer.get(), protectedSizeMax, &resultLen);
-        if (!status.isOK()) {
-            severe() << "Unable to finalize DataProtector while closing RemoveSaver: "
-                     << redact(status);
-            fassertFailed(34350);
-        }
-
-        _out->write(reinterpret_cast<const char*>(protectedBuffer.get()), resultLen);
-        if (_out->fail()) {
-            severe() << "Couldn't write finalized DataProtector data to: " << _file.string()
-                     << " for remove saving: " << redact(errnoWithDescription());
-            fassertFailed(34351);
-        }
-
-        protectedBuffer.reset(new uint8_t[protectedSizeMax]);
-        status = _protector->finalizeTag(protectedBuffer.get(), protectedSizeMax, &resultLen);
-        if (!status.isOK()) {
-            severe() << "Unable to get finalizeTag from DataProtector while closing RemoveSaver: "
-                     << redact(status);
-            fassertFailed(34352);
-        }
-        if (resultLen != _protector->getNumberOfBytesReservedForTag()) {
-            severe() << "Attempted to write tag of size " << resultLen
-                     << " when DataProtector only reserved "
-                     << _protector->getNumberOfBytesReservedForTag() << " bytes";
-            fassertFailed(34353);
-        }
-        _out->seekp(0);
-        _out->write(reinterpret_cast<const char*>(protectedBuffer.get()), resultLen);
-        if (_out->fail()) {
-            severe() << "Couldn't write finalizeTag from DataProtector to: " << _file.string()
-                     << " for remove saving: " << redact(errnoWithDescription());
-            fassertFailed(34354);
-        }
-    }
-}
-
-Status Helpers::RemoveSaver::goingToDelete(const BSONObj& o) {
-    if (!_out) {
-        // We don't expect to ever pass "" to create_directories below, but catch
-        // this anyway as per SERVER-26412.
-        invariant(!_root.empty());
-        boost::filesystem::create_directories(_root);
-        _out.reset(new ofstream(_file.string().c_str(), ios_base::out | ios_base::binary));
-        if (_out->fail()) {
-            string msg = str::stream() << "couldn't create file: " << _file.string()
-                                       << " for remove saving: " << redact(errnoWithDescription());
-            error() << msg;
-            _out.reset();
-            _out = 0;
-            return Status(ErrorCodes::FileNotOpen, msg);
-        }
-    }
-
-    const uint8_t* data = reinterpret_cast<const uint8_t*>(o.objdata());
-    size_t dataSize = o.objsize();
-
-    std::unique_ptr<uint8_t[]> protectedBuffer;
-    if (_protector) {
-        auto encryptionHooks = EncryptionHooks::get(getGlobalServiceContext());
-        invariant(encryptionHooks->enabled());
-
-        size_t protectedSizeMax = dataSize + encryptionHooks->additionalBytesForProtectedBuffer();
-        protectedBuffer.reset(new uint8_t[protectedSizeMax]);
-
-        size_t resultLen;
-        Status status = _protector->protect(
-            data, dataSize, protectedBuffer.get(), protectedSizeMax, &resultLen);
-        if (!status.isOK()) {
-            return status;
-        }
-
-        data = protectedBuffer.get();
-        dataSize = resultLen;
-    }
-
-    _out->write(reinterpret_cast<const char*>(data), dataSize);
-    if (_out->fail()) {
-        string msg = str::stream() << "couldn't write document to file: " << _file.string()
-                                   << " for remove saving: " << redact(errnoWithDescription());
-        error() << msg;
-        return Status(ErrorCodes::OperationFailed, msg);
-    }
-    return Status::OK();
-}
-
-
 }  // namespace mongo
diff --git a/src/mongo/db/dbhelpers.h b/src/mongo/db/dbhelpers.h
index 5f7344bb3b5..ecaa5f7af8e 100644
--- a/src/mongo/db/dbhelpers.h
+++ b/src/mongo/db/dbhelpers.h
@@ -30,18 +30,13 @@
 
 #pragma once
 
-#include <boost/filesystem/path.hpp>
-#include <memory>
-
 #include "mongo/db/namespace_string.h"
 #include "mongo/db/record_id.h"
-#include "mongo/db/storage/data_protector.h"
 
 namespace mongo {
 
 class Collection;
 class Database;
-class DataProtector;
 class OperationContext;
 class QueryRequest;
 
@@ -52,7 +47,6 @@ class QueryRequest;
  * all helpers assume locking is handled above them
  */
 struct Helpers {
-    class RemoveSaver;
 
     /* fetch a single object from collection ns that matches query.
        set your db SavedContext first.
@@ -150,46 +144,6 @@ struct Helpers {
      * Does not oplog the operation.
      */
     static void emptyCollection(OperationContext* opCtx, const NamespaceString& nss);
-
-    /**
-     * for saving deleted bson objects to a flat file
-     */
-    class RemoveSaver {
-        MONGO_DISALLOW_COPYING(RemoveSaver);
-
-    public:
-        RemoveSaver(const std::string& type, const std::string& ns, const std::string& why);
-        ~RemoveSaver();
-
-        /**
-         * Writes document to file. File is created lazily before writing the first document.
-         * Returns error status if the file could not be created or if there were errors writing
-         * to the file.
-         */
-        Status goingToDelete(const BSONObj& o);
-
-        /**
-         * A path object describing the directory containing the file with deleted documents.
-         */
-        const auto& root() const& {
-            return _root;
-        }
-        void root() && = delete;
-
-        /**
-         * A path object describing the actual file containing BSON documents.
-         */
-        const auto& file() const& {
-            return _file;
-        }
-        void file() && = delete;
-
-    private:
-        boost::filesystem::path _root;
-        boost::filesystem::path _file;
-        std::unique_ptr<DataProtector> _protector;
-        std::unique_ptr<std::ostream> _out;
-    };
 };
 
 }  // namespace mongo
diff --git a/src/mongo/db/repl/SConscript b/src/mongo/db/repl/SConscript
index ae8989e9702..1221abc160d 100644
--- a/src/mongo/db/repl/SConscript
+++ b/src/mongo/db/repl/SConscript
@@ -522,6 +522,7 @@ env.Library(
         '$BUILD_DIR/mongo/db/catalog/catalog_helpers',
         '$BUILD_DIR/mongo/db/catalog/database_holder',
         '$BUILD_DIR/mongo/db/s/sharding_runtime_d',
+        '$BUILD_DIR/mongo/db/storage/remove_saver',
         '$BUILD_DIR/mongo/util/fail_point',
         '$BUILD_DIR/mongo/db/dbhelpers',
         '$BUILD_DIR/mongo/db/query_exec',
diff --git a/src/mongo/db/repl/rollback_impl.cpp b/src/mongo/db/repl/rollback_impl.cpp
index 511660973a0..7c7bc94cf38 100644
--- a/src/mongo/db/repl/rollback_impl.cpp
+++ b/src/mongo/db/repl/rollback_impl.cpp
@@ -41,7 +41,6 @@
 #include "mongo/db/commands.h"
 #include "mongo/db/concurrency/d_concurrency.h"
 #include "mongo/db/db_raii.h"
-#include "mongo/db/dbhelpers.h"
 #include "mongo/db/kill_sessions_local.h"
 #include "mongo/db/logical_time_validator.h"
 #include "mongo/db/operation_context.h"
@@ -57,6 +56,7 @@
 #include "mongo/db/server_parameters.h"
 #include "mongo/db/server_recovery.h"
 #include "mongo/db/server_transactions_metrics.h"
+#include "mongo/db/storage/remove_saver.h"
 #include "mongo/s/catalog/type_config_version.h"
 #include "mongo/util/log.h"
 #include "mongo/util/scopeguard.h"
@@ -973,7 +973,7 @@ void RollbackImpl::_writeRollbackFileForNamespace(OperationContext* opCtx,
                                                   UUID uuid,
                                                   NamespaceString nss,
                                                   const SimpleBSONObjUnorderedSet& idSet) {
-    Helpers::RemoveSaver removeSaver(kRollbackRemoveSaverType, nss.ns(), kRollbackRemoveSaverWhy);
+    RemoveSaver removeSaver(kRollbackRemoveSaverType, nss.ns(), kRollbackRemoveSaverWhy);
     log() << "Preparing to write deleted documents to a rollback file for collection " << nss.ns()
           << " with uuid " << uuid.toString() << " to " << removeSaver.file().generic_string();
 
diff --git a/src/mongo/db/repl/rs_rollback.cpp b/src/mongo/db/repl/rs_rollback.cpp
index eae4a7b87cb..6896955ec78 100644
--- a/src/mongo/db/repl/rs_rollback.cpp
+++ b/src/mongo/db/repl/rs_rollback.cpp
@@ -72,6 +72,7 @@
 #include "mongo/db/repl/rslog.h"
 #include "mongo/db/s/shard_identity_rollback_notifier.h"
 #include "mongo/db/session_catalog_mongod.h"
+#include "mongo/db/storage/remove_saver.h"
 #include "mongo/db/transaction_participant.h"
 #include "mongo/s/client/shard_registry.h"
 #include "mongo/s/grid.h"
@@ -747,7 +748,7 @@ void dropCollection(OperationContext* opCtx,
                     Collection* collection,
                     Database* db) {
     if (RollbackImpl::shouldCreateDataFiles()) {
-        Helpers::RemoveSaver removeSaver("rollback", "", nss.ns());
+        RemoveSaver removeSaver("rollback", "", nss.ns());
 
         // Performs a collection scan and writes all documents in the collection to disk
         // in order to keep an archive of items that were rolled back.
@@ -1259,13 +1260,13 @@ void rollback_internal::syncFixUp(OperationContext* opCtx,
         // while rolling back createCollection operations.
 
         const auto& uuid = nsAndGoodVersionsByDocID.first;
-        unique_ptr<Helpers::RemoveSaver> removeSaver;
+        unique_ptr<RemoveSaver> removeSaver;
         invariant(!fixUpInfo.collectionsToDrop.count(uuid));
 
         NamespaceString nss = catalog.lookupNSSByUUID(uuid);
 
         if (RollbackImpl::shouldCreateDataFiles()) {
-            removeSaver = std::make_unique<Helpers::RemoveSaver>("rollback", "", nss.ns());
+            removeSaver = std::make_unique<RemoveSaver>("rollback", "", nss.ns());
         }
 
         const auto& goodVersionsByDocID = nsAndGoodVersionsByDocID.second;
diff --git a/src/mongo/db/s/SConscript b/src/mongo/db/s/SConscript
index e348ad6e4ad..128f6985853 100644
--- a/src/mongo/db/s/SConscript
+++ b/src/mongo/db/s/SConscript
@@ -75,6 +75,7 @@ env.Library(
         '$BUILD_DIR/mongo/db/ops/write_ops_exec',
         '$BUILD_DIR/mongo/db/repl/oplog',
         '$BUILD_DIR/mongo/db/repl/repl_coordinator_interface',
+        '$BUILD_DIR/mongo/db/storage/remove_saver',
         '$BUILD_DIR/mongo/db/rw_concern_d',
         '$BUILD_DIR/mongo/s/client/shard_local',
         '$BUILD_DIR/mongo/s/sharding_initialization',
diff --git a/src/mongo/db/s/collection_range_deleter.cpp b/src/mongo/db/s/collection_range_deleter.cpp
index 8856d53d8a2..ead8f441758 100644
--- a/src/mongo/db/s/collection_range_deleter.cpp
+++ b/src/mongo/db/s/collection_range_deleter.cpp
@@ -55,6 +55,7 @@
 #include "mongo/db/s/sharding_statistics.h"
 #include "mongo/db/server_parameters.h"
 #include "mongo/db/service_context.h"
+#include "mongo/db/storage/remove_saver.h"
 #include "mongo/db/write_concern.h"
 #include "mongo/executor/task_executor.h"
 #include "mongo/util/log.h"
@@ -386,7 +387,7 @@ StatusWith<int> CollectionRangeDeleter::_doDeletion(OperationContext* opCtx,
         return {ErrorCodes::InternalError, msg};
     }
 
-    boost::optional<Helpers::RemoveSaver> saver;
+    boost::optional<RemoveSaver> saver;
     if (serverGlobalParams.moveParanoia) {
         saver.emplace("moveChunk", nss.ns(), "cleaning");
     }
diff --git a/src/mongo/db/s/migration_destination_manager.cpp b/src/mongo/db/s/migration_destination_manager.cpp
index cacf25a608c..69f62df8751 100644
--- a/src/mongo/db/s/migration_destination_manager.cpp
+++ b/src/mongo/db/s/migration_destination_manager.cpp
@@ -57,6 +57,7 @@
 #include "mongo/db/s/start_chunk_clone_request.h"
 #include "mongo/db/server_parameters.h"
 #include "mongo/db/service_context.h"
+#include "mongo/db/storage/remove_saver.h"
 #include "mongo/s/catalog/type_chunk.h"
 #include "mongo/s/client/shard_registry.h"
 #include "mongo/s/grid.h"
@@ -1040,7 +1041,7 @@ bool MigrationDestinationManager::_applyMigrateOp(OperationContext* opCtx,
 
     // Deleted documents
     if (xfer["deleted"].isABSONObj()) {
-        boost::optional<Helpers::RemoveSaver> rs;
+        boost::optional<RemoveSaver> rs;
         if (serverGlobalParams.moveParanoia) {
             rs.emplace("moveChunk", _nss.ns(), "removedDuring");
         }
diff --git a/src/mongo/db/storage/SConscript b/src/mongo/db/storage/SConscript
index 8cd5b9cb4f4..e82a86d5cdb 100644
--- a/src/mongo/db/storage/SConscript
+++ b/src/mongo/db/storage/SConscript
@@ -341,3 +341,15 @@ env.Benchmark(
         '$BUILD_DIR/mongo/base',
     ],
 )
+
+env.Library(
+    target='remove_saver',
+    source=[
+        'remove_saver.cpp',
+    ],
+    LIBDEPS=[
+        'encryption_hooks',
+        'storage_options',
+        '$BUILD_DIR/mongo/base',
+    ]
+)
diff --git a/src/mongo/db/storage/remove_saver.cpp b/src/mongo/db/storage/remove_saver.cpp
new file mode 100644
index 00000000000..505e9083b75
--- /dev/null
+++ b/src/mongo/db/storage/remove_saver.cpp
@@ -0,0 +1,179 @@
+
+/**
+ *    Copyright (C) 2018-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kStorage
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/storage/remove_saver.h"
+
+#include <boost/filesystem/operations.hpp>
+#include <fstream>
+
+#include "mongo/db/service_context.h"
+#include "mongo/db/storage/encryption_hooks.h"
+#include "mongo/db/storage/storage_options.h"
+#include "mongo/util/errno_util.h"
+#include "mongo/util/log.h"
+
+
+using std::ios_base;
+using std::ofstream;
+using std::stringstream;
+using std::string;
+
+namespace mongo {
+
+RemoveSaver::RemoveSaver(const string& a, const string& b, const string& why) {
+    static int NUM = 0;
+
+    _root = storageGlobalParams.dbpath;
+    if (a.size())
+        _root /= a;
+    if (b.size())
+        _root /= b;
+    verify(a.size() || b.size());
+
+    _file = _root;
+
+    stringstream ss;
+    ss << why << "." << terseCurrentTime(false) << "." << NUM++ << ".bson";
+    _file /= ss.str();
+
+    auto encryptionHooks = EncryptionHooks::get(getGlobalServiceContext());
+    if (encryptionHooks->enabled()) {
+        _protector = encryptionHooks->getDataProtector();
+        _file += encryptionHooks->getProtectedPathSuffix();
+    }
+}
+
+RemoveSaver::~RemoveSaver() {
+    if (_protector && _out) {
+        auto encryptionHooks = EncryptionHooks::get(getGlobalServiceContext());
+        invariant(encryptionHooks->enabled());
+
+        size_t protectedSizeMax = encryptionHooks->additionalBytesForProtectedBuffer();
+        std::unique_ptr<uint8_t[]> protectedBuffer(new uint8_t[protectedSizeMax]);
+
+        size_t resultLen;
+        Status status = _protector->finalize(protectedBuffer.get(), protectedSizeMax, &resultLen);
+        if (!status.isOK()) {
+            severe() << "Unable to finalize DataProtector while closing RemoveSaver: "
+                     << redact(status);
+            fassertFailed(34350);
+        }
+
+        _out->write(reinterpret_cast<const char*>(protectedBuffer.get()), resultLen);
+        if (_out->fail()) {
+            severe() << "Couldn't write finalized DataProtector data to: " << _file.string()
+                     << " for remove saving: " << redact(errnoWithDescription());
+            fassertFailed(34351);
+        }
+
+        protectedBuffer.reset(new uint8_t[protectedSizeMax]);
+        status = _protector->finalizeTag(protectedBuffer.get(), protectedSizeMax, &resultLen);
+        if (!status.isOK()) {
+            severe() << "Unable to get finalizeTag from DataProtector while closing RemoveSaver: "
+                     << redact(status);
+            fassertFailed(34352);
+        }
+
+        if (resultLen != _protector->getNumberOfBytesReservedForTag()) {
+            severe() << "Attempted to write tag of size " << resultLen
+                     << " when DataProtector only reserved "
+                     << _protector->getNumberOfBytesReservedForTag() << " bytes";
+            fassertFailed(34353);
+        }
+
+        _out->seekp(0);
+        _out->write(reinterpret_cast<const char*>(protectedBuffer.get()), resultLen);
+
+        if (_out->fail()) {
+            severe() << "Couldn't write finalizeTag from DataProtector to: " << _file.string()
+                     << " for remove saving: " << redact(errnoWithDescription());
+            fassertFailed(34354);
+        }
+    }
+}
+
+Status RemoveSaver::goingToDelete(const BSONObj& o) {
+    if (!_out) {
+        // We don't expect to ever pass "" to create_directories below, but catch
+        // this anyway as per SERVER-26412.
+        invariant(!_root.empty());
+        boost::filesystem::create_directories(_root);
+        _out.reset(new ofstream(_file.string().c_str(), ios_base::out | ios_base::binary));
+
+        if (_out->fail()) {
+            string msg = str::stream() << "couldn't create file: " << _file.string()
+                                       << " for remove saving: " << redact(errnoWithDescription());
+            error() << msg;
+            _out.reset();
+            _out = 0;
+            return Status(ErrorCodes::FileNotOpen, msg);
+        }
+    }
+
+    const uint8_t* data = reinterpret_cast<const uint8_t*>(o.objdata());
+    size_t dataSize = o.objsize();
+
+    std::unique_ptr<uint8_t[]> protectedBuffer;
+    if (_protector) {
+        auto encryptionHooks = EncryptionHooks::get(getGlobalServiceContext());
+        invariant(encryptionHooks->enabled());
+
+        size_t protectedSizeMax = dataSize + encryptionHooks->additionalBytesForProtectedBuffer();
+        protectedBuffer.reset(new uint8_t[protectedSizeMax]);
+
+        size_t resultLen;
+        Status status = _protector->protect(
+            data, dataSize, protectedBuffer.get(), protectedSizeMax, &resultLen);
+
+        if (!status.isOK()) {
+            return status;
+        }
+
+        data = protectedBuffer.get();
+        dataSize = resultLen;
+    }
+
+    _out->write(reinterpret_cast<const char*>(data), dataSize);
+
+    if (_out->fail()) {
+        string msg = str::stream() << "couldn't write document to file: " << _file.string()
+                                   << " for remove saving: " << redact(errnoWithDescription());
+        error() << msg;
+        return Status(ErrorCodes::OperationFailed, msg);
+    }
+
+    return Status::OK();
+}
+
+}  // namespace mongo
diff --git a/src/mongo/db/storage/remove_saver.h b/src/mongo/db/storage/remove_saver.h
new file mode 100644
index 00000000000..78057622444
--- /dev/null
+++ b/src/mongo/db/storage/remove_saver.h
@@ -0,0 +1,85 @@
+
+/**
+ *    Copyright (C) 2018-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+#include <boost/filesystem/path.hpp>
+#include <memory>
+#include <ostream>
+#include <string>
+
+#include "mongo/base/disallow_copying.h"
+#include "mongo/base/status.h"
+#include "mongo/db/jsobj.h"
+#include "mongo/db/storage/data_protector.h"
+
+namespace mongo {
+
+/**
+ * for saving deleted bson objects to a flat file
+ */
+class RemoveSaver {
+    MONGO_DISALLOW_COPYING(RemoveSaver);
+
+public:
+    RemoveSaver(const std::string& type, const std::string& ns, const std::string& why);
+    ~RemoveSaver();
+
+    /**
+     * Writes document to file. File is created lazily before writing the first document.
+     * Returns error status if the file could not be created or if there were errors writing
+     * to the file.
+     */
+    Status goingToDelete(const BSONObj& o);
+
+    /**
+     * A path object describing the directory containing the file with deleted documents.
+     */
+    const auto& root() const& {
+        return _root;
+    }
+    void root() && = delete;
+
+    /**
+     * A path object describing the actual file containing BSON documents.
+     */
+    const auto& file() const& {
+        return _file;
+    }
+    void file() && = delete;
+
+private:
+    boost::filesystem::path _root;
+    boost::filesystem::path _file;
+    std::unique_ptr<DataProtector> _protector;
+    std::unique_ptr<std::ostream> _out;
+};
+
+}  // namespace mongo