Check refcount in RemoveManyObjectStorageOperation::finalize instead of execute

src/Disks/ObjectStorages/DiskObjectStorageTransaction.cpp

@@ -6,6 +6,8 @@
 #include <Common/logger_useful.h>
 #include <Common/Exception.h>
 
+#include <Disks/ObjectStorages/MetadataStorageFromDisk.h>
+
 namespace DB
 {
 
@@ -63,11 +65,18 @@ struct PureMetadataObjectStorageOperation final : public IDiskObjectStorageOpera
     std::string getInfoForLog() const override { return fmt::format("PureMetadataObjectStorageOperation"); }
 };
 
+
+struct ObjectsToRemove
+{
+    StoredObjects objects;
+    UnlinkMetadataFileOperationOutcomePtr unlink_outcome;
+};
+
 struct RemoveObjectStorageOperation final : public IDiskObjectStorageOperation
 {
     std::string path;
     bool delete_metadata_only;
-    StoredObjects objects_to_remove;
+    ObjectsToRemove objects_to_remove;
     bool if_exists;
     bool remove_from_cache = false;
 
@@ -103,15 +112,12 @@ struct RemoveObjectStorageOperation final : public IDiskObjectStorageOperation
 
         try
         {
-            uint32_t hardlink_count = metadata_storage.getHardlinkCount(path);
             auto objects = metadata_storage.getStorageObjects(path);
 
-            tx->unlinkMetadata(path);
+            auto unlink_outcome = tx->unlinkMetadata(path);
 
-            if (hardlink_count == 0)
-            {
-                objects_to_remove = std::move(objects);
-            }
+            if (unlink_outcome)
+                objects_to_remove = ObjectsToRemove{std::move(objects), std::move(unlink_outcome)};
         }
         catch (const Exception & e)
         {
@@ -140,8 +146,11 @@ struct RemoveObjectStorageOperation final : public IDiskObjectStorageOperation
         /// due to network error or similar. And when it will retry an operation it may receive
         /// a 404 HTTP code. We don't want to threat this code as a real error for deletion process
         /// (e.g. throwing some exceptions) and thus we just use method `removeObjectsIfExists`
-        if (!delete_metadata_only && !objects_to_remove.empty())
-            object_storage.removeObjectsIfExist(objects_to_remove);
+        if (!delete_metadata_only && !objects_to_remove.objects.empty()
+            && objects_to_remove.unlink_outcome->num_hardlinks == 0)
+        {
+            object_storage.removeObjectsIfExist(objects_to_remove.objects);
+        }
     }
 };
 
@@ -150,7 +159,9 @@ struct RemoveManyObjectStorageOperation final : public IDiskObjectStorageOperati
     RemoveBatchRequest remove_paths;
     bool keep_all_batch_data;
     NameSet file_names_remove_metadata_only;
-    StoredObjects objects_to_remove;
+
+    std::vector<ObjectsToRemove> objects_to_remove;
+
     bool remove_from_cache = false;
 
     RemoveManyObjectStorageOperation(
@@ -174,7 +185,6 @@ struct RemoveManyObjectStorageOperation final : public IDiskObjectStorageOperati
     {
         for (const auto & [path, if_exists] : remove_paths)
         {
-
             if (!metadata_storage.exists(path))
             {
                 if (if_exists)
@@ -188,14 +198,12 @@ struct RemoveManyObjectStorageOperation final : public IDiskObjectStorageOperati
 
             try
             {
-                uint32_t hardlink_count = metadata_storage.getHardlinkCount(path);
                 auto objects = metadata_storage.getStorageObjects(path);
-
-                tx->unlinkMetadata(path);
-
-                /// File is really redundant
-                if (hardlink_count == 0 && !keep_all_batch_data && !file_names_remove_metadata_only.contains(fs::path(path).filename()))
-                    std::move(objects.begin(), objects.end(), std::back_inserter(objects_to_remove));
+                auto unlink_outcome = tx->unlinkMetadata(path);
+                if (unlink_outcome && !keep_all_batch_data && !file_names_remove_metadata_only.contains(fs::path(path).filename()))
+                {
+                    objects_to_remove.emplace_back(ObjectsToRemove{std::move(objects), std::move(unlink_outcome)});
+                }
             }
             catch (const Exception & e)
             {
@@ -215,26 +223,31 @@ struct RemoveManyObjectStorageOperation final : public IDiskObjectStorageOperati
 
     void undo() override
     {
-
     }
 
     void finalize() override
     {
+        StoredObjects remove_from_remote;
+        for (auto && [objects, unlink_outcome] : objects_to_remove)
+        {
+            if (unlink_outcome->num_hardlinks == 0)
+                std::move(objects.begin(), objects.end(), std::back_inserter(remove_from_remote));
+        }
+
         /// Read comment inside RemoveObjectStorageOperation class
         /// TL;DR Don't pay any attention to 404 status code
-        if (!objects_to_remove.empty())
-            object_storage.removeObjectsIfExist(objects_to_remove);
+        if (!remove_from_remote.empty())
+            object_storage.removeObjectsIfExist(remove_from_remote);
     }
 };
 
 
 struct RemoveRecursiveObjectStorageOperation final : public IDiskObjectStorageOperation
 {
     std::string path;
-    std::unordered_map<std::string, StoredObjects> objects_to_remove;
+    std::unordered_map<std::string, ObjectsToRemove> objects_to_remove_by_path;
     bool keep_all_batch_data;
     NameSet file_names_remove_metadata_only;
-    StoredObjects objects_to_remove_from_cache;
 
     RemoveRecursiveObjectStorageOperation(
         IObjectStorage & object_storage_,
@@ -261,14 +274,11 @@ struct RemoveRecursiveObjectStorageOperation final : public IDiskObjectStorageOp
         {
             try
             {
-                uint32_t hardlink_count = metadata_storage.getHardlinkCount(path_to_remove);
                 auto objects_paths = metadata_storage.getStorageObjects(path_to_remove);
-
-                tx->unlinkMetadata(path_to_remove);
-
-                if (hardlink_count == 0)
+                auto unlink_outcome = tx->unlinkMetadata(path_to_remove);
+                if (unlink_outcome)
                 {
-                    objects_to_remove[path_to_remove] = std::move(objects_paths);
+                    objects_to_remove_by_path[path_to_remove] = ObjectsToRemove{std::move(objects_paths), std::move(unlink_outcome)};
                 }
             }
             catch (const Exception & e)
@@ -318,11 +328,12 @@ struct RemoveRecursiveObjectStorageOperation final : public IDiskObjectStorageOp
         if (!keep_all_batch_data)
         {
             StoredObjects remove_from_remote;
-            for (auto && [local_path, remote_paths] : objects_to_remove)
+            for (auto && [local_path, objects_to_remove] : objects_to_remove_by_path)
             {
                 if (!file_names_remove_metadata_only.contains(fs::path(local_path).filename()))
                 {
-                    std::move(remote_paths.begin(), remote_paths.end(), std::back_inserter(remove_from_remote));
+                    if (objects_to_remove.unlink_outcome->num_hardlinks == 0)
+                        std::move(objects_to_remove.objects.begin(), objects_to_remove.objects.end(), std::back_inserter(remove_from_remote));
                 }
             }
             /// Read comment inside RemoveObjectStorageOperation class

src/Disks/ObjectStorages/IMetadataStorage.h

@@ -22,6 +22,8 @@ namespace ErrorCodes
 }
 
 class IMetadataStorage;
+struct UnlinkMetadataFileOperationOutcome;
+using UnlinkMetadataFileOperationOutcomePtr = std::shared_ptr<UnlinkMetadataFileOperationOutcome>;
 
 /// Tries to provide some "transactions" interface, which allow
 /// to execute (commit) operations simultaneously. We don't provide
@@ -127,9 +129,10 @@ class IMetadataTransaction : private boost::noncopyable
 
     /// Unlink metadata file and do something special if required
     /// By default just remove file (unlink file).
-    virtual void unlinkMetadata(const std::string & path)
+    virtual UnlinkMetadataFileOperationOutcomePtr unlinkMetadata(const std::string & path)
     {
         unlinkFile(path);
+        return nullptr;
     }
 
     virtual ~IMetadataTransaction() = default;

src/Disks/ObjectStorages/MetadataStorageFromDisk.cpp

@@ -340,9 +340,12 @@ void MetadataStorageFromDiskTransaction::addBlobToMetadata(const std::string & p
     addOperation(std::make_unique<AddBlobOperation>(path, blob_name, metadata_storage.object_storage_root_path, size_in_bytes, *metadata_storage.disk, metadata_storage));
 }
 
-void MetadataStorageFromDiskTransaction::unlinkMetadata(const std::string & path)
+UnlinkMetadataFileOperationOutcomePtr MetadataStorageFromDiskTransaction::unlinkMetadata(const std::string & path)
 {
-    addOperation(std::make_unique<UnlinkMetadataFileOperation>(path, *metadata_storage.disk, metadata_storage));
+    auto operation = std::make_unique<UnlinkMetadataFileOperation>(path, *metadata_storage.getDisk(), metadata_storage);
+    auto result = operation->outcome;
+    addOperation(std::move(operation));
+    return result;
 }
 
 }

src/Disks/ObjectStorages/MetadataStorageFromDisk.h

@@ -11,6 +11,9 @@
 namespace DB
 {
 
+struct UnlinkMetadataFileOperationOutcome;
+using UnlinkMetadataFileOperationOutcomePtr = std::shared_ptr<UnlinkMetadataFileOperationOutcome>;
+
 /// Store metadata on a separate disk
 /// (used for object storages, like S3 and related).
 class MetadataStorageFromDisk final : public IMetadataStorage
@@ -131,7 +134,7 @@ class MetadataStorageFromDiskTransaction final : public IMetadataTransaction
 
     void replaceFile(const std::string & path_from, const std::string & path_to) override;
 
-    void unlinkMetadata(const std::string & path) override;
+    UnlinkMetadataFileOperationOutcomePtr unlinkMetadata(const std::string & path) override;
 
 
 };

src/Disks/ObjectStorages/MetadataStorageFromDiskTransactionOperations.cpp

@@ -319,6 +319,8 @@ void UnlinkMetadataFileOperation::execute(std::unique_lock<SharedMutex> & metada
         write_operation = std::make_unique<WriteFileOperation>(path, disk, metadata->serializeToString());
         write_operation->execute(metadata_lock);
     }
+    outcome->num_hardlinks = ref_count;
+
     unlink_operation = std::make_unique<UnlinkFileOperation>(path, disk);
     unlink_operation->execute(metadata_lock);
 }
@@ -334,6 +336,9 @@ void UnlinkMetadataFileOperation::undo()
 
     if (write_operation)
         write_operation->undo();
+
+    /// Update outcome to reflect the fact that we have restored the file.
+    outcome->num_hardlinks++;
 }
 
 void SetReadonlyFileOperation::execute(std::unique_lock<SharedMutex> & metadata_lock)

src/Disks/ObjectStorages/MetadataStorageFromDiskTransactionOperations.h

@@ -3,6 +3,8 @@
 #include <Common/SharedMutex.h>
 #include <Disks/ObjectStorages/IMetadataStorage.h>
 
+#include <numeric>
+
 namespace DB
 {
 class MetadataStorageFromDisk;
@@ -242,9 +244,19 @@ struct AddBlobOperation final : public IMetadataOperation
     std::unique_ptr<WriteFileOperation> write_operation;
 };
 
+/// Return the result of operation to the caller.
+/// It is used in `IDiskObjectStorageOperation::finalize` after metadata transaction executed to make decision on blob removal.
+struct UnlinkMetadataFileOperationOutcome
+{
+    UInt32 num_hardlinks = std::numeric_limits<UInt32>::max();
+};
+
+using UnlinkMetadataFileOperationOutcomePtr = std::shared_ptr<UnlinkMetadataFileOperationOutcome>;
 
 struct UnlinkMetadataFileOperation final : public IMetadataOperation
 {
+    const UnlinkMetadataFileOperationOutcomePtr outcome = std::make_shared<UnlinkMetadataFileOperationOutcome>();
+
     UnlinkMetadataFileOperation(
         const std::string & path_,
         IDisk & disk_,

src/Disks/ObjectStorages/MetadataStorageFromPlainObjectStorage.cpp

@@ -135,9 +135,11 @@ void MetadataStorageFromPlainObjectStorageTransaction::addBlobToMetadata(
 {
     /// Noop, local metadata files is only one file, it is the metadata file itself.
 }
-void MetadataStorageFromPlainObjectStorageTransaction::unlinkMetadata(const std::string &)
+
+UnlinkMetadataFileOperationOutcomePtr MetadataStorageFromPlainObjectStorageTransaction::unlinkMetadata(const std::string &)
 {
-    /// Noop, no separate metadata.
+    /// No hardlinks, so will always remove file.
+    return std::make_shared<UnlinkMetadataFileOperationOutcome>(UnlinkMetadataFileOperationOutcome{0});
 }
 
 }

src/Disks/ObjectStorages/MetadataStorageFromPlainObjectStorage.h

@@ -9,6 +9,9 @@
 namespace DB
 {
 
+struct UnlinkMetadataFileOperationOutcome;
+using UnlinkMetadataFileOperationOutcomePtr = std::shared_ptr<UnlinkMetadataFileOperationOutcome>;
+
 /// Object storage is used as a filesystem, in a limited form:
 /// - no directory concept, files only
 /// - no stat/chmod/...
@@ -104,7 +107,7 @@ class MetadataStorageFromPlainObjectStorageTransaction final : public IMetadataT
 
     void unlinkFile(const std::string & path) override;
 
-    void unlinkMetadata(const std::string & path) override;
+    UnlinkMetadataFileOperationOutcomePtr unlinkMetadata(const std::string & path) override;
 
     void commit() override
     {

tests/integration/test_alter_moving_garbage/configs/config.d/storage_conf.xml

@@ -1,12 +1,18 @@
 <clickhouse>
     <storage_configuration>
         <disks>
-            <s3>
+            <s31>
                 <type>s3</type>
                 <endpoint>http://minio1:9001/root/data/</endpoint>
                 <access_key_id>minio</access_key_id>
                 <secret_access_key>minio123</secret_access_key>
-            </s3>
+            </s31>
+            <s32>
+                <type>s3</type>
+                <endpoint>http://minio1:9001/root/data2/</endpoint>
+                <access_key_id>minio</access_key_id>
+                <secret_access_key>minio123</secret_access_key>
+            </s32>
         </disks>
         <policies>
             <two_disks>
@@ -15,10 +21,17 @@
                         <disk>default</disk>
                     </default>
                     <external>
-                        <disk>s3</disk>
+                        <disk>s31</disk>
                     </external>
                 </volumes>
             </two_disks>
+            <one_disk>
+                <volumes>
+                    <external>
+                        <disk>s32</disk>
+                    </external>
+                </volumes>
+            </one_disk>
         </policies>
     </storage_configuration>