levelDB-LAB1-pzy_ckx/db/write_batch.cc

// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// WriteBatch::rep_ :=
//    sequence: fixed64
//    count: fixed32
//    data: record[count]
// record :=
//    kTypeValue varstring varstring         |
//    kTypeDeletion varstring
// varstring :=
//    len: varint32
//    data: uint8[len]

#include "leveldb/write_batch.h"

#include "db/dbformat.h"
#include "db/memtable.h"
#include "db/write_batch_internal.h"
#include "leveldb/db.h"
#include "util/coding.h"

#include <sstream>  // For std::ostringstream 心
#include <cstdint>  // 引入uint64_t类型,燕
#include "leveldb/env.h" //燕
namespace leveldb {

// WriteBatch header has an 8-byte sequence number followed by a 4-byte count.
static const size_t kHeader = 12;

WriteBatch::WriteBatch() { Clear(); }

WriteBatch::~WriteBatch() = default;

WriteBatch::Handler::~Handler() = default;

void WriteBatch::Clear() {
  rep_.clear();
  rep_.resize(kHeader);
}

size_t WriteBatch::ApproximateSize() const { return rep_.size(); }

Status WriteBatch::Iterate(Handler* handler) const {
  Slice input(rep_);
  if (input.size() < kHeader) {
    return Status::Corruption("malformed WriteBatch (too small)");
  }

  input.remove_prefix(kHeader);
  Slice key, value;
  int found = 0;
  while (!input.empty()) {
    found++;
    char tag = input[0];
    input.remove_prefix(1);
    switch (tag) {
      case kTypeValue:
        if (GetLengthPrefixedSlice(&input, &key) &&
            GetLengthPrefixedSlice(&input, &value)) {
          handler->Put(key, value);
        } else {
          return Status::Corruption("bad WriteBatch Put");
        }
        break;
      case kTypeDeletion:
        if (GetLengthPrefixedSlice(&input, &key)) {
          handler->Delete(key);
        } else {
          return Status::Corruption("bad WriteBatch Delete");
        }
        break;
      default:
        return Status::Corruption("unknown WriteBatch tag");
    }
  }
  if (found != WriteBatchInternal::Count(this)) {
    return Status::Corruption("WriteBatch has wrong count");
  } else {
    return Status::OK();
  }
}

int WriteBatchInternal::Count(const WriteBatch* b) {
  return DecodeFixed32(b->rep_.data() + 8);
}

void WriteBatchInternal::SetCount(WriteBatch* b, int n) {
  EncodeFixed32(&b->rep_[8], n);
}

SequenceNumber WriteBatchInternal::Sequence(const WriteBatch* b) {
  return SequenceNumber(DecodeFixed64(b->rep_.data()));
}

void WriteBatchInternal::SetSequence(WriteBatch* b, SequenceNumber seq) {
  EncodeFixed64(&b->rep_[0], seq);
}

void WriteBatch::Put(const Slice& key, const Slice& value) {
  WriteBatchInternal::SetCount(this, WriteBatchInternal::Count(this) + 1);
  rep_.push_back(static_cast<char>(kTypeValue));
  PutLengthPrefixedSlice(&rep_, key);
  PutLengthPrefixedSlice(&rep_, value);
}

// void WriteBatch::Put(const Slice& key, const Slice& value, std::uint64_t ttl) {
//     WriteBatchInternal::SetCount(this, WriteBatchInternal::Count(this) + 1);
//     rep_.push_back(static_cast<char>(kTypeValue));
//     PutLengthPrefixedSlice(&rep_, key);

//     // 获取当前时间并计算过期时间
//     uint64_t current_time = Env::Default()->NowMicros() / 1000000; // 当前时间（秒）
//     uint64_t expire_time = current_time + ttl; // 计算未来的过期时间

//     // 将过期时间编码为64位整数
//     rep_.append(reinterpret_cast<const char*>(&expire_time), sizeof(expire_time)); // 添加过期时间戳

//     // 添加原始值
//     PutLengthPrefixedSlice(&rep_, value);
// }

void WriteBatch::Put(const Slice& key, const Slice& value, std::uint64_t ttl) {
  WriteBatchInternal::SetCount(this, WriteBatchInternal::Count(this) + 1);
  rep_.push_back(static_cast<char>(kTypeValue));
  PutLengthPrefixedSlice(&rep_, key);

  // 获取当前时间
  
  auto now = std::chrono::system_clock::now();
    
  // 加上ttl
  auto future_time = now + std::chrono::seconds(ttl);
   
  // 转换为 time_t
  std::time_t future_time_t = std::chrono::system_clock::to_time_t(future_time);
    
  // 将 time_t 转换为 tm 结构
  std::tm* local_tm = std::localtime(&future_time_t);

  // 格式化为字符串
  char buffer[20];  // 格式化字符串的缓冲区
  std::strftime(buffer, sizeof(buffer), "%Y-%m-%d %H:%M:%S", local_tm);
  std::string future_time_str(buffer);

  // 拼接原本的值和时间字符串
  std::string combined_str = value.ToString() + future_time_str;
  PutLengthPrefixedSlice(&rep_, Slice(combined_str));

} // 心

void WriteBatch::Delete(const Slice& key) {
  WriteBatchInternal::SetCount(this, WriteBatchInternal::Count(this) + 1);
  rep_.push_back(static_cast<char>(kTypeDeletion));
  PutLengthPrefixedSlice(&rep_, key);
}

void WriteBatch::Append(const WriteBatch& source) {
  WriteBatchInternal::Append(this, &source);
}

namespace {
class MemTableInserter : public WriteBatch::Handler {
 public:
  SequenceNumber sequence_;
  MemTable* mem_;

  void Put(const Slice& key, const Slice& value) override {
    mem_->Add(sequence_, kTypeValue, key, value);
    sequence_++;
  }
  void Delete(const Slice& key) override {
    mem_->Add(sequence_, kTypeDeletion, key, Slice());
    sequence_++;
  }
};
}  // namespace

Status WriteBatchInternal::InsertInto(const WriteBatch* b, MemTable* memtable) {
  MemTableInserter inserter;
  inserter.sequence_ = WriteBatchInternal::Sequence(b);
  inserter.mem_ = memtable;
  return b->Iterate(&inserter);
}

void WriteBatchInternal::SetContents(WriteBatch* b, const Slice& contents) {
  assert(contents.size() >= kHeader);
  b->rep_.assign(contents.data(), contents.size());
}

void WriteBatchInternal::Append(WriteBatch* dst, const WriteBatch* src) {
  SetCount(dst, Count(dst) + Count(src));
  assert(src->rep_.size() >= kHeader);
  dst->rep_.append(src->rep_.data() + kHeader, src->rep_.size() - kHeader);
}

}  // namespace leveldb