1 // Copyright (C) 2019 Google LLC 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 // Author: [email protected] (Scott Banachowski) 16 // [email protected] (Vladimir Marko) 17 // 18 // Interface class for disk-backed storage. 19 20 #ifndef ICING_LEGACY_INDEX_ICING_STORAGE_H_ 21 #define ICING_LEGACY_INDEX_ICING_STORAGE_H_ 22 23 #include <cstdint> 24 #include <string> 25 26 #include "icing/util/crc32.h" 27 28 namespace icing { 29 namespace lib { 30 31 // Abstract base class for interface. 32 class IIcingStorage { 33 public: 34 // Any resource that is not removed in the Close() function should 35 // be removed in the child's destructor. 36 virtual ~IIcingStorage() = default; 37 38 // This is called to upgrade to a new version. 39 // Returns true if the data store can be upgraded successfully. 40 virtual bool UpgradeTo(int new_version) = 0; 41 42 // This must be called before the object is usable. 43 // Returns true if the storage is in a usable state. 44 virtual bool Init() = 0; 45 46 // Attempts to init the given IIcingStorage. On failure, clears the underlying 47 // data and tries again. Returns false of the second init is also a failure. InitWithRetry(IIcingStorage * file_in)48 static bool InitWithRetry(IIcingStorage* file_in) { 49 if (file_in->Init()) { 50 return true; 51 } 52 return file_in->Remove() && file_in->Init(); 53 } 54 55 // Closes all files and system resources. 56 // Init() must be called before the object is used again. 57 virtual void Close() = 0; 58 59 // Closes all system resources, then removes the backing file. 60 // Init() is required before the object is used again. 61 // Returns true on success. 62 virtual bool Remove() = 0; 63 64 // Syncs any unwritten data to disk. 65 virtual bool Sync() = 0; 66 67 // Gets the total amount of disk usage for the object (i.e. the sum of the 68 // bytes of all underlying files). 69 // Note: reported values are estimated via the number of blocks the file takes 70 // up on disk. Sparse files are reported as their physical disk usage, as 71 // opposed to the logical size when read. 72 // Returns kBadFileSize on error. 73 virtual uint64_t GetDiskUsage() const = 0; 74 75 // Updates any checksums that this storage maintains. 76 // By default, does nothing. UpdateCrc()77 virtual Crc32 UpdateCrc() { return Crc32(); } 78 79 virtual void GetDebugInfo(int verbosity, std::string* out) const = 0; 80 81 protected: 82 IIcingStorage() = default; 83 84 private: 85 // Document stores are non-copyable. 86 IIcingStorage(const IIcingStorage&); 87 IIcingStorage& operator=(const IIcingStorage&); 88 }; 89 90 } // namespace lib 91 } // namespace icing 92 93 #endif // ICING_LEGACY_INDEX_ICING_STORAGE_H_ 94