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 #ifndef ICING_LEGACY_INDEX_ICING_LITE_INDEX_HEADER_H_ 16 #define ICING_LEGACY_INDEX_ICING_LITE_INDEX_HEADER_H_ 17 18 #include "icing/legacy/core/icing-string-util.h" 19 #include "icing/store/document-id.h" 20 21 namespace icing { 22 namespace lib { 23 24 // A wrapper around the actual mmapped header data. 25 class LiteIndex_Header { 26 public: 27 virtual ~LiteIndex_Header() = default; 28 29 // Returns true if the magic of the header matches the hard-coded magic 30 // value associated with this header format. 31 virtual bool check_magic() const = 0; 32 33 virtual uint32_t lite_index_crc() const = 0; 34 virtual void set_lite_index_crc(uint32_t crc) = 0; 35 36 virtual uint32_t last_added_docid() const = 0; 37 virtual void set_last_added_docid(uint32_t last_added_docid) = 0; 38 39 virtual uint32_t cur_size() const = 0; 40 virtual void set_cur_size(uint32_t cur_size) = 0; 41 42 virtual uint32_t searchable_end() const = 0; 43 virtual void set_searchable_end(uint32_t searchable_end) = 0; 44 45 virtual uint32_t CalculateHeaderCrc() const = 0; 46 47 virtual void Reset() = 0; 48 }; 49 50 class LiteIndex_HeaderImpl : public LiteIndex_Header { 51 public: 52 struct HeaderData { 53 static const uint32_t kMagic = 0xb4fb8792; 54 55 uint32_t lite_index_crc; 56 uint32_t magic; 57 // This field is available to be reclaimed for another purpose without 58 // forcing a change in header size. NOTE: claiming this fields doesn't 59 // guarantee that the newly claimed field will have the proper value. If you 60 // are depending on the value of this field then you will have to have a 61 // migration - either a one-time event during Upgrade() or Init() or 62 // determined by a flag change in Init(). 63 uint32_t padding; 64 uint32_t last_added_docid; 65 uint32_t cur_size; 66 uint32_t searchable_end; 67 }; 68 LiteIndex_HeaderImpl(HeaderData * hdr)69 explicit LiteIndex_HeaderImpl(HeaderData *hdr) : hdr_(hdr) {} 70 check_magic()71 bool check_magic() const override { 72 return hdr_->magic == HeaderData::kMagic; 73 } 74 lite_index_crc()75 uint32_t lite_index_crc() const override { return hdr_->lite_index_crc; } set_lite_index_crc(uint32_t crc)76 void set_lite_index_crc(uint32_t crc) override { hdr_->lite_index_crc = crc; } 77 last_added_docid()78 uint32_t last_added_docid() const override { return hdr_->last_added_docid; } set_last_added_docid(uint32_t last_added_docid)79 void set_last_added_docid(uint32_t last_added_docid) override { 80 hdr_->last_added_docid = last_added_docid; 81 } 82 cur_size()83 uint32_t cur_size() const override { return hdr_->cur_size; } set_cur_size(uint32_t cur_size)84 void set_cur_size(uint32_t cur_size) override { hdr_->cur_size = cur_size; } 85 searchable_end()86 uint32_t searchable_end() const override { return hdr_->searchable_end; } set_searchable_end(uint32_t searchable_end)87 void set_searchable_end(uint32_t searchable_end) override { 88 hdr_->searchable_end = searchable_end; 89 } 90 CalculateHeaderCrc()91 uint32_t CalculateHeaderCrc() const override { 92 return IcingStringUtil::UpdateCrc32( 93 0, reinterpret_cast<const char *>(hdr_) + offsetof(HeaderData, magic), 94 sizeof(HeaderData) - offsetof(HeaderData, magic)); 95 } 96 Reset()97 void Reset() override { 98 hdr_->lite_index_crc = 0; 99 hdr_->magic = HeaderData::kMagic; 100 hdr_->last_added_docid = kInvalidDocumentId; 101 hdr_->cur_size = 0; 102 hdr_->searchable_end = 0; 103 } 104 105 private: 106 HeaderData *hdr_; 107 }; 108 static_assert(24 == sizeof(LiteIndex_HeaderImpl::HeaderData), 109 "sizeof(HeaderData) != 24"); 110 111 } // namespace lib 112 } // namespace icing 113 114 #endif // ICING_LEGACY_INDEX_ICING_LITE_INDEX_HEADER_H_ 115