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索引处理类的设计与实现

發布時間：2025/4/5 编程问答 20 豆豆

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文章目錄

- 1 索引處理類的頭文件定義
- 2 構造函數和析構函數
- 3 create方法實現
- 4 load方法實現
- 5 remove和flush方法的實現
- 6 索引初始化測試
- 7 寫入文件實現
- - 7.1 哈希查找實現
  - 7.2 哈希插入實現
  - 7.3 更新塊信息
  - 7.4 寫入文件測試
- 8 讀文件實現
- - 8.1 讀MetaInfo
  - 8.2 讀流程實現
- 9 刪除文件實現
- - 9.1 刪除MetaInfo
  - 9.2 刪除文件流程實現

1 索引處理類的頭文件定義

#ifndef QINIU_LARGEFILE_INDEX_HANDLE_H_ #define QINIU_LARGEFILE_INDEX_HANDLE_H_#include "common.h" #include "mmap_file_op.h"namespace qiniu {namespace largefile{struct IndexHeader{public:IndexHeader(){memset(this, 0, sizeof(IndexHeader));}BlockInfo block_info_; //meta block infoint32_t bucket_size_; //hash bucket sizeint32_t data_file_offset_; //offset to write next data in blockint32_t index_file_size_; //offset after: index_header + all bucketsint32_t free_head_offset_;// free meta node list, for reuse};class IndexHandle{public:IndexHandle( const std::string& base_path, const uint32_t main_block_id);~IndexHandle();int create(const uint32_t logic_block_id, const int32_t bucket_size, const MMapOption map_option);int load(const uint32_t logic_block_id, const int32_t bucket_size, const MMapOption map_option);//remove index: unmmap and unlink fileint remove(const uint32_t logic_block_id);int flush();IndexHeader * index_header(){return reinterpret_cast<IndexHeader *>(file_op_->get_map_data());}int update_block_info(const OperType oper_type, const uint32_t modify_size);BlockInfo* block_info(){return reinterpret_cast<BlockInfo*> (file_op_->get_map_data());}int32_t* bucket_slot(){return reinterpret_cast<int32_t*> (reinterpret_cast<char*>(file_op_->get_map_data()) + sizeof(IndexHeader));}int32_t bucket_size() const {return reinterpret_cast<IndexHeader *>(file_op_->get_map_data())->bucket_size_;}int32_t get_block_data_offset() const{return reinterpret_cast<IndexHeader*>(file_op_->get_map_data())->data_file_offset_;}int32_t free_head_offset() const {return reinterpret_cast<IndexHeader*>(file_op_->get_map_data())->free_head_offset_;}void commit_block_data_offset(const int file_size){reinterpret_cast<IndexHeader*>(file_op_->get_map_data())->data_file_offset_ += file_size;}int32_t write_segment_meta(const uint64_t key, MetaInfo &meta);int32_t read_segment_meta(const uint64_t key, MetaInfo &meta);int32_t delete_segment_meta(const uint64_t key);int32_t hash_find(const uint64_t key, int32_t& current_offset, int32_t& previous_offset);int32_t hash_insert(const uint64_t key, int32_t previous_offset, MetaInfo &meta);private:bool hash_compare(const uint64_t left_key, const uint64_t right_key){return (left_key == right_key);}MMapFileOperation* file_op_;bool is_load_;};} } #endif //QINIU_LARGEFILE_INDEX_HANDLE_H_

2 構造函數和析構函數

IndexHandle::IndexHandle(const std::string& base_path, const uint32_t main_block_id){//create file_op_ handle objectstd::stringstream tmp_stream;tmp_stream << base_path<< INDEX_DIR_PREFIX<< main_block_id; // /root/martin/index/1std::string index_path;tmp_stream>>index_path;file_op_ = new MMapFileOperation(index_path, O_CREAT | O_RDWR | O_LARGEFILE);is_load_ = false;}IndexHandle::~IndexHandle(){if(file_op_){delete file_op_;file_op_ = NULL;}}

3 create方法實現

int IndexHandle::create(const uint32_t logic_block_id, const int32_t bucket_size, const MMapOption map_option) {int ret = TFS_SUCCESS;if(debug) printf(" create index , block id: %u , bucket size: %d, max_mmap_size: %d, first mmap size: %d, per mmap size: %d\n",logic_block_id, bucket_size, map_option.max_mmap_size_, map_option.first_mmap_size_, map_option.per_mmap_size_);if(is_load_){return EXIT_INDEX_ALREADY_LOADED_ERROR;}int64_t file_size = file_op_->get_file_size();if(file_size < 0){return TFS_ERROR;}else if(file_size == 0) //empty file{IndexHeader i_header;i_header.block_info_.block_id_ = logic_block_id;i_header.block_info_.seq_no_ = 1;i_header.bucket_size_ = bucket_size;i_header.index_file_size_ = sizeof(IndexHeader) + bucket_size * sizeof(int32_t);//index header + total bucketschar * init_data = new char[i_header.index_file_size_];memcpy(init_data, &i_header, sizeof(IndexHeader));memset(init_data + sizeof(IndexHeader), 0, i_header.index_file_size_ - sizeof(IndexHeader));//write index header and buckets into index file ret = file_op_->pwrite_file(init_data, i_header.index_file_size_, 0);delete[] init_data;init_data = NULL;if(ret != TFS_SUCCESS ){return ret;}ret = file_op_->flush_file();if(ret != TFS_SUCCESS ){return ret;}}else //file size > 0 , index already exist{return EXIT_META_UNEXPECT_FOUND_ERROR;}ret = file_op_->mmap_file(map_option);if(ret != TFS_SUCCESS){return ret;}is_load_ = true;if(debug) printf("init blockid: %d index successful. data file size: %d, index file size: %d, bucket_size: %d, free head offset: %d, seqno: %d, size: %d, filecount: %d, del_size: %d, del_file_count: %d version: %d\n",logic_block_id, index_header()->data_file_offset_, index_header()->index_file_size_,index_header()->bucket_size_, index_header()->free_head_offset_, block_info()->seq_no_, block_info()->size_,block_info()->file_count_, block_info()->del_size_, block_info()->del_file_count_, block_info()->version_);return TFS_SUCCESS; }

4 load方法實現

int IndexHandle::load(const uint32_t logic_block_id, const int32_t _bucket_size, const MMapOption map_option) {int ret = TFS_SUCCESS;if(is_load_){return EXIT_INDEX_ALREADY_LOADED_ERROR;}int64_t file_size = file_op_->get_file_size();if(file_size <0){return file_size;}else if(file_size == 0)//empty file {return EXIT_INDEX_CORRUPT_ERROR;}MMapOption tmp_map_option = map_option;if(file_size> tmp_map_option.first_mmap_size_ && file_size <= tmp_map_option.max_mmap_size_){tmp_map_option.first_mmap_size_ = file_size;}ret = file_op_->mmap_file(tmp_map_option);if( ret != TFS_SUCCESS){return ret;}if(debug) printf("IndexHandle::load - bucket_size(): %d, index_header()->bucket_size_: %d, block id: %d\n", bucket_size(), index_header()->bucket_size_, block_info()->block_id_);if(0 == bucket_size() || 0 == block_info()->block_id_){fprintf(stderr, "Index corrupt error. blockid: %u, bucket size: %d\n", block_info()->block_id_, bucket_size());return EXIT_INDEX_CORRUPT_ERROR;}//check file sizeint32_t index_file_size = sizeof(IndexHeader) + bucket_size() * sizeof(int32_t);if(file_size < index_file_size){fprintf(stderr, "Index corrupt error,blockid: %u, bucket size: %d, file size: %ld, index file size: %d\n", block_info()->block_id_, bucket_size(), file_size,index_file_size);return EXIT_INDEX_CORRUPT_ERROR;}//check block id if(logic_block_id != block_info()->block_id_){fprintf(stderr, "block id conflict. blockid: %u, index blockid： %u\n", logic_block_id, block_info()->block_id_);return EXIT_BLOCKID_CONFLICT_ERROR;}//check bucket_sizeif(_bucket_size != bucket_size()){fprintf(stderr, "Index configure error, old bucket size: %d, new bucket size: %d\n", bucket_size(), _bucket_size);return EXIT_BUCKET_CONFIGURE_ERROR;}is_load_ = true;if(debug) printf("load blockid: %d index successful. data file size: %d, index file size: %d, bucket_size: %d, free head offset: %d, seqno: %d, size: %d, filecount: %d, del_size: %d, del_file_count: %d version: %d\n",logic_block_id, index_header()->data_file_offset_, index_header()->index_file_size_,index_header()->bucket_size_, index_header()->free_head_offset_, block_info()->seq_no_, block_info()->size_,block_info()->file_count_, block_info()->del_size_, block_info()->del_file_count_, block_info()->version_);return TFS_SUCCESS; }

5 remove和flush方法的實現

int IndexHandle::remove(const uint32_t logic_block_id) {if(is_load_){if(logic_block_id != block_info()->block_id_){fprintf(stderr, "block id conflict. bolckid: %d, index blokid: %d\n", logic_block_id, block_info()->block_id_);return EXIT_BLOCKID_CONFLICT_ERROR;}}int ret = file_op_->munmap_file();if( TFS_SUCCESS != ret){return ret;}ret = file_op_->unlink_file();return ret; }int IndexHandle::flush() {int ret = file_op_->flush_file();if(TFS_SUCCESS != ret){fprintf(stderr, "index flush fail , ret: %d error desc: %s\n", ret, strerror(errno));}return ret; }

6 索引初始化測試

先來看一下塊初始化的流程：

測試代碼如下：

7 寫入文件實現

寫入文件的流程如下：

7.1 哈希查找實現

int IndexHandle::hash_find(const uint64_t key, int32_t& current_offset, int32_t& previous_offset) {int ret = TFS_SUCCESS;MetaInfo meta_info;current_offset = 0;previous_offset = 0;//1.確定key 存放的桶(slot)的位置int32_t slot = static_cast<uint32_t>(key) % bucket_size();//2.讀取桶首節點存儲的第一個節點的偏移量，如果偏移量為零，直接返回 EXIT_META_NOT_FOUND_ERROR//3.根據偏移量讀取存儲的metainfo //4.與key進行比較，相等則設置current_offset 和previous_offset 并返回TFS_SUCCESS,否則繼續執行5//5. 從metainfo 中取得下一個節點的在文件中的偏移量,如果偏移量為零，直接返回 EXIT_META_NOT_FOUND_ERROR,// 否則，跳轉至3繼續循環執行int32_t pos = bucket_slot()[slot];for(;pos != 0; ){ret = file_op_->pread_file(reinterpret_cast<char*>(&meta_info), sizeof(MetaInfo), pos);if( TFS_SUCCESS != ret){return ret;}if( hash_compare( key, meta_info.get_key() ) ){current_offset = pos;return TFS_SUCCESS;}previous_offset = pos;pos = meta_info.get_next_meta_offset();}return EXIT_META_NOT_FOUND_ERROR;}

7.2 哈希插入實現

int32_t IndexHandle::hash_insert(const uint64_t key, int32_t previous_offset, MetaInfo &meta) {int ret = TFS_SUCCESS;MetaInfo tmp_meta_info;int32_t current_offset = 0;//1.確定key 存放的桶(slot)的位置int32_t slot = static_cast<uint32_t>(key) % bucket_size();//2.確定meta 節點存儲在文件中的偏移量if(free_head_offset() != 0){ret = file_op_->pread_file(reinterpret_cast<char*>(&tmp_meta_info), sizeof(MetaInfo), free_head_offset());if( TFS_SUCCESS != ret){return ret;}current_offset = index_header()->free_head_offset_;if(debug) printf("reuse metainfo, current_offset: %d\n", current_offset);index_header()->free_head_offset_ = tmp_meta_info.get_next_meta_offset();}else {current_offset = index_header()->index_file_size_;index_header()->index_file_size_ += sizeof(MetaInfo);}//3.將meta 節點寫入索引文件中meta.set_next_meta_offset(0);ret = file_op_->pwrite_file( reinterpret_cast<const char*>(&meta), sizeof(MetaInfo), current_offset);if( TFS_SUCCESS != ret){index_header()->index_file_size_ -= sizeof(MetaInfo);return ret;}//4. 將meta 節點插入到哈希鏈表中//當前一個節點已經存在if( 0 != previous_offset){ret = file_op_->pread_file(reinterpret_cast<char*>(&tmp_meta_info), sizeof(MetaInfo), previous_offset);if( TFS_SUCCESS != ret){index_header()->index_file_size_ -= sizeof(MetaInfo);return ret;}tmp_meta_info.set_next_meta_offset(current_offset);ret = file_op_->pwrite_file( reinterpret_cast<const char*>(&tmp_meta_info), sizeof(MetaInfo), previous_offset);if( TFS_SUCCESS != ret){index_header()->index_file_size_ -= sizeof(MetaInfo);return ret;}}else { //不存在前一個節點的情況bucket_slot()[slot] = current_offset;}return TFS_SUCCESS; }

7.3 更新塊信息

int IndexHandle::write_segment_meta(const uint64_t key, MetaInfo &meta) {int32_t current_offset = 0, previous_offset = 0;//思考？ key 存在嗎？存在=>處理？不存在=>處理？//1.從文件哈希表中查找key 是否存在 hash_find(key, current_offset, previous_offset);int ret = hash_find(key, current_offset, previous_offset);if( TFS_SUCCESS == ret){return EXIT_META_UNEXPECT_FOUND_ERROR;}else if( EXIT_META_NOT_FOUND_ERROR != ret){return ret;}//2.不存在就寫入meta 到文件哈希表中 hash_insert(key, previous_offset, meta);ret = hash_insert(key, previous_offset, meta);return ret; }int IndexHandle::update_block_info(const OperType oper_type, const uint32_t modify_size) {if( block_info()->block_id_ == 0){return EXIT_BLOCKID_ZERO_ERROR;}if( oper_type == C_OPER_INSERT ){++block_info()->version_;++block_info()->file_count_;++block_info()->seq_no_;block_info()->size_ += modify_size;}else if( oper_type == C_OPER_DELETE ){++block_info()->version_;--block_info()->file_count_;block_info()->size_ -= modify_size;++block_info()->del_file_count_;block_info()->del_size_ += modify_size;}if(debug) printf("update block info. blockid: %u, version: %u, file count: %u, size: %u, del file count: %u, del size: %u, seq no: %u, oper type: %d\n",block_info()->block_id_, block_info()->version_, block_info()->file_count_, block_info()->size_,block_info()->del_file_count_, block_info()->del_size_, block_info()->seq_no_, oper_type);return TFS_SUCCESS; }

7.4 寫入文件測試

#include "common.h" #include "file_op.h" #include "index_handle.h" #include <sstream>using namespace qiniu; using namespace std;const static largefile::MMapOption mmap_option = {1024000, 4096, 4096}; //內存映射的參數 const static uint32_t main_blocksize = 1024*1024*64; //主塊文件的大小 const static uint32_t bucket_size = 1000; //哈希桶的大小 static int32_t block_id = 1;static int debug = 1;int main(int argc, char **argv) //argv[0]="rm" argv[1]="-f" argv[2] ="a.out" {std::string mainblock_path;std::string index_path;int32_t ret = largefile::TFS_SUCCESS;cout<<" Type your bockid :"<<endl;cin>> block_id;if(block_id < 1){cerr<<" Invalid blockid, exit."<<endl;exit(-1);}//1. 加載索引文件largefile::IndexHandle *index_handle = new largefile::IndexHandle(".", block_id); //索引文件句柄if(debug) printf("load index ...\n");ret = index_handle->load(block_id, bucket_size, mmap_option);if(ret != largefile::TFS_SUCCESS){fprintf(stderr, "load index %d failed.\n", block_id);//delete mainblock;delete index_handle;exit(-2);}//2. 寫入文件到主塊文件中std::stringstream tmp_stream;tmp_stream<< "." << largefile::MAINBLOCK_DIR_PREFIX << block_id;tmp_stream >> mainblock_path;largefile::FileOperation *mainblock = new largefile::FileOperation(mainblock_path, O_RDWR | O_LARGEFILE | O_CREAT);char buffer[4096];memset(buffer, '6', sizeof(buffer));int32_t data_offset = index_handle->get_block_data_offset();uint32_t file_no = index_handle->block_info()->seq_no_;if( (ret = mainblock->pwrite_file(buffer, sizeof(buffer), data_offset)) != largefile::TFS_SUCCESS){fprintf(stderr, "write to main block failed. ret: %d, reason: %s\n", ret, strerror(errno));mainblock->close_file();delete mainblock;delete index_handle;exit(-3);}//3. 索引文件中寫入Metainfolargefile::MetaInfo meta;meta.set_file_id( file_no );meta.set_offset( data_offset );meta.set_size( sizeof(buffer) );ret = index_handle->write_segment_meta(meta.get_key(), meta);if(ret == largefile::TFS_SUCCESS){//1.更新索引頭部信息index_handle->commit_block_data_offset( sizeof(buffer) );//2. 更新塊信息index_handle->update_block_info(largefile::C_OPER_INSERT, sizeof(buffer) );ret = index_handle->flush();if(ret != largefile::TFS_SUCCESS){fprintf(stderr, "flush mainblock %d failed. file no: %u \n", block_id, file_no);}}else {fprintf(stderr, "write_segement_meta - mainblock %d failed. file no: %u\n", block_id, file_no);}if(ret != largefile::TFS_SUCCESS){fprintf(stderr,"write to mainblock %d failed. file no: %u\n", block_id, file_no);}else {if(debug) printf("write successfully. file_no : %u , block_id: %d\n", file_no, block_id);}mainblock->close_file();delete mainblock;delete index_handle;return 0; }

8 讀文件實現

8.1 讀MetaInfo

int32_t IndexHandle::read_segment_meta(const uint64_t key, MetaInfo &meta) {int32_t current_offset = 0, previous_offset = 0;//1.確定key 存放的桶(slot)的位置//int32_t slot = static_cast<uint32_t>(key) % bucket_size();int32_t ret = hash_find(key, current_offset, previous_offset);if( TFS_SUCCESS == ret) //exist{ret = file_op_->pread_file(reinterpret_cast<char *> (&meta), sizeof(MetaInfo), current_offset);return ret;}else {return ret;} }

8.2 讀流程實現

#include "common.h" #include "file_op.h" #include "index_handle.h" #include <sstream>using namespace qiniu; using namespace std;const static largefile::MMapOption mmap_option = {1024000, 4096, 4096}; //內存映射的參數 const static uint32_t main_blocksize = 1024*1024*64; //主塊文件的大小 const static uint32_t bucket_size = 1000; //哈希桶的大小 static int32_t block_id = 1;static int debug = 1;int main(int argc, char **argv) //argv[0]="rm" argv[1]="-f" argv[2] ="a.out" {std::string mainblock_path;std::string index_path;int32_t ret = largefile::TFS_SUCCESS;cout<<" Type your bockid :"<<endl;cin>> block_id;if(block_id < 1){cerr<<" Invalid blockid, exit."<<endl;exit(-1);}//1. 加載索引文件largefile::IndexHandle *index_handle = new largefile::IndexHandle(".", block_id); //索引文件句柄if(debug) printf("load index ...\n");ret = index_handle->load(block_id, bucket_size, mmap_option);if(ret != largefile::TFS_SUCCESS){fprintf(stderr, "load index %d failed.\n", block_id);//delete mainblock;delete index_handle;exit(-2);}//2. 讀取文件的meta info.uint64_t file_id = 0;cout<<" Type your file_id :"<<endl;cin>> file_id;if(file_id < 1){cerr<<" Invalid fileid, exit."<<endl;exit(-2);}largefile::MetaInfo meta;ret = index_handle->read_segment_meta( file_id, meta);if(ret != largefile::TFS_SUCCESS){fprintf(stderr, "read_segment_meta error. file_id: %lu, ret: %d\n", file_id, ret);exit(-3);}//3. 根據meta info 讀取文件std::stringstream tmp_stream;tmp_stream<< "." << largefile::MAINBLOCK_DIR_PREFIX << block_id;tmp_stream >> mainblock_path;largefile::FileOperation *mainblock = new largefile::FileOperation(mainblock_path, O_RDWR );char *buffer = new char[meta.get_size() + 1];ret = mainblock->pread_file(buffer, meta.get_size(), meta.get_offset());if(ret != largefile::TFS_SUCCESS){fprintf(stderr, "read from main block failed. ret: %d, reason: %s\n", ret, strerror(errno));mainblock->close_file();delete mainblock;delete index_handle;exit(-3);}buffer[meta.get_size()] = '\0';printf("read size %d, content: %s\n", meta.get_size(), buffer);mainblock->close_file();delete mainblock;delete index_handle;return 0; }

9 刪除文件實現

9.1 刪除MetaInfo

int32_t IndexHandle::delete_segment_meta(const uint64_t key) {int32_t current_offset = 0, previous_offset = 0;int32_t ret = hash_find(key, current_offset, previous_offset);if( ret != TFS_SUCCESS ){return ret;}MetaInfo meta_info;ret = file_op_->pread_file(reinterpret_cast<char *>(&meta_info), sizeof(MetaInfo), current_offset);if ( TFS_SUCCESS != ret ){return ret;}int32_t next_pos = meta_info.get_next_meta_offset();if(previous_offset == 0){int32_t slot = static_cast<uint32_t> (key) % bucket_size();bucket_slot()[slot] = next_pos;}else {MetaInfo pre_meta_info;ret = file_op_->pread_file(reinterpret_cast<char *>(&pre_meta_info), sizeof(MetaInfo), previous_offset);if ( TFS_SUCCESS != ret ){return ret;}pre_meta_info.set_next_meta_offset(next_pos);ret = file_op_->pwrite_file(reinterpret_cast<char *>(&pre_meta_info), sizeof(MetaInfo), previous_offset);if ( TFS_SUCCESS != ret ){return ret;}}//把刪除節點加入可重用節點鏈表（下一個小節實現）meta_info.set_next_meta_offset(free_head_offset());// index_header()->free_head_offset_;ret = file_op_->pwrite_file(reinterpret_cast<char *>(&meta_info), sizeof(MetaInfo), current_offset);if( TFS_SUCCESS != ret ){return ret;}index_header()->free_head_offset_ = current_offset;if(debug) printf("delete_segment_meta - reuse metainfo, current_offset: %d\n", current_offset);update_block_info(C_OPER_DELETE, meta_info.get_size());return TFS_SUCCESS;}

9.2 刪除文件流程實現

參考資料：

C/C++從入門到精通-高級程序員之路【奇牛學院】

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