199 lines
5.3 KiB
199 lines
5.3 KiB
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#include "util/coding.h"
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#include "leveldb/db.h"
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#include <iostream>
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#include<vector>
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namespace leveldb {
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void PutFixed32(std::string* dst, uint32_t value) {
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char buf[sizeof(value)];
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EncodeFixed32(buf, value);
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dst->append(buf, sizeof(buf));
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}
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void PutFixed64(std::string* dst, uint64_t value) {
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char buf[sizeof(value)];
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EncodeFixed64(buf, value);
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dst->append(buf, sizeof(buf));
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}
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char* EncodeVarint32(char* dst, uint32_t v) {
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// Operate on characters as unsigneds
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uint8_t* ptr = reinterpret_cast<uint8_t*>(dst);
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static const int B = 128;
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if (v < (1 << 7)) {
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*(ptr++) = v;
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} else if (v < (1 << 14)) {
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*(ptr++) = v | B;
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*(ptr++) = v >> 7;
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} else if (v < (1 << 21)) {
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*(ptr++) = v | B;
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*(ptr++) = (v >> 7) | B;
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*(ptr++) = v >> 14;
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} else if (v < (1 << 28)) {
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*(ptr++) = v | B;
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*(ptr++) = (v >> 7) | B;
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*(ptr++) = (v >> 14) | B;
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*(ptr++) = v >> 21;
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} else {
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*(ptr++) = v | B;
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*(ptr++) = (v >> 7) | B;
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*(ptr++) = (v >> 14) | B;
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*(ptr++) = (v >> 21) | B;
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*(ptr++) = v >> 28;
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}
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return reinterpret_cast<char*>(ptr);
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}
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void PutVarint32(std::string* dst, uint32_t v) {
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char buf[5];
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char* ptr = EncodeVarint32(buf, v);
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// printf("加入的长度%d\n", ptr - buf);
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dst->append(buf, ptr - buf);
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// printf("插入之后的长度为：%d", dst->length());
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}
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char* EncodeVarint64(char* dst, uint64_t v) {
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static const int B = 128;
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uint8_t* ptr = reinterpret_cast<uint8_t*>(dst);
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while (v >= B) {
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*(ptr++) = v | B;
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v >>= 7;
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}
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*(ptr++) = static_cast<uint8_t>(v);
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return reinterpret_cast<char*>(ptr);
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}
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void PutVarint64(std::string* dst, uint64_t v) {
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char buf[10];
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char* ptr = EncodeVarint64(buf, v);
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dst->append(buf, ptr - buf);
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}
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void PutLengthPrefixedSlice(std::string* dst, const Slice& value) {
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PutVarint32(dst, value.size());
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dst->append(value.data(), value.size());
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}
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int VarintLength(uint64_t v) {
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int len = 1;
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while (v >= 128) {
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v >>= 7;
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len++;
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}
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return len;
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}
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const char* GetVarint32PtrFallback(const char* p, const char* limit,
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uint32_t* value) {
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uint32_t result = 0;
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for (uint32_t shift = 0; shift <= 28 && p < limit; shift += 7) {
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uint32_t byte = *(reinterpret_cast<const uint8_t*>(p));
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p++;
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if (byte & 128) {
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// More bytes are present
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result |= ((byte & 127) << shift);
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} else {
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result |= (byte << shift);
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*value = result;
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return reinterpret_cast<const char*>(p);
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}
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}
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return nullptr;
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}
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bool GetVarint32(Slice* input, uint32_t* value) {
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const char* p = input->data();
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const char* limit = p + input->size();
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const char* q = GetVarint32Ptr(p, limit, value);
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if (q == nullptr) {
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return false;
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} else {
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*input = Slice(q, limit - q);
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return true;
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}
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}
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const char* GetVarint64Ptr(const char* p, const char* limit, uint64_t* value) {
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uint64_t result = 0;
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for (uint32_t shift = 0; shift <= 63 && p < limit; shift += 7) {
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uint64_t byte = *(reinterpret_cast<const uint8_t*>(p));
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p++;
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if (byte & 128) {
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// More bytes are present
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result |= ((byte & 127) << shift);
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} else {
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result |= (byte << shift);
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*value = result;
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return reinterpret_cast<const char*>(p);
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}
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}
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return nullptr;
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}
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bool GetVarint64(Slice* input, uint64_t* value) {
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const char* p = input->data();
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const char* limit = p + input->size();
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const char* q = GetVarint64Ptr(p, limit, value);
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if (q == nullptr) {
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return false;
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} else {
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*input = Slice(q, limit - q);
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return true;
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}
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}
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bool GetLengthPrefixedSlice(Slice* input, Slice* result) {
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uint32_t len;
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if (GetVarint32(input, &len) && input->size() >= len) {
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*result = Slice(input->data(), len);
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input->remove_prefix(len);
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return true;
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} else {
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return false;
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}
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}
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// 序列化为字符串
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std::string SerializeValue(const FieldArray& fields) {
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std::string serialized_value = "";
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uint32_t num = fields.size();
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// std::cout<< "加入的值中包含的字段数："<<num<<std::endl;
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PutVarint32(&serialized_value, num); // 编码字段个数
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for (uint32_t i = 0; i < num; i++) { // 依次编码字段名和字段值
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PutLengthPrefixedSlice(&serialized_value, fields[i].first);
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PutLengthPrefixedSlice(&serialized_value, fields[i].second);
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}
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return serialized_value;
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}
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// 反序列化为字段数组
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FieldArray ParseValue(const std::string& value_str) {
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uint32_t num=0;
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FieldArray fields;
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Slice value_sl(value_str); // 把字符串类型的值转为slice类型
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if (GetVarint32(&value_sl, &num)) {
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for (uint32_t i = 0; i < num; i++)
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{
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Slice field_name, field_value;
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GetLengthPrefixedSlice(&value_sl, &field_name);
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GetLengthPrefixedSlice(&value_sl, &field_value);
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fields.push_back({field_name.ToString().substr(0, field_name.size()), field_value.ToString().substr(0, field_value.size())});
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// std::string str = field_name.data().substr(0, field_name.size());
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//std::cout << "字段名："<< strncpy(str1, field_name.data(),field_name.size())<< std::endl;
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// std::cout<<field_name.data()<<"__"<<field_value.data()<< std::endl;
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}
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}
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return fields;
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}
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} // namespace leveldb
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