diff --git a/db/db_impl.cc b/db/db_impl.cc index 2f66816..904b11c 100644 --- a/db/db_impl.cc +++ b/db/db_impl.cc @@ -1122,17 +1122,17 @@ Status DBImpl::Get(const ReadOptions& options, const Slice& key, Status s; MutexLock l(&mutex_); SequenceNumber snapshot; - if (options.snapshot != nullptr) { + if (options.snapshot != nullptr) {//判断读取选项是否包含用户提供的快照。如果有，则用快照中的序列号。燕 snapshot = static_cast(options.snapshot)->sequence_number(); } else { - snapshot = versions_->LastSequence(); + snapshot = versions_->LastSequence(); //否则，使用当前最新的序列号。燕 } MemTable* mem = mem_; MemTable* imm = imm_; Version* current = versions_->current(); - mem->Ref(); + mem->Ref(); //增加引用计数以确保这些对象在方法执行过程中不会被删除 燕 if (imm != nullptr) imm->Ref(); current->Ref(); @@ -1144,24 +1144,24 @@ Status DBImpl::Get(const ReadOptions& options, const Slice& key, mutex_.Unlock(); // First look in the memtable, then in the immutable memtable (if any). LookupKey lkey(key, snapshot); - if (mem->Get(lkey, value, &s)) { + if (mem->Get(lkey, value, &s)) { //尝试从当前 memtable 中获取键的值。如果找到，则直接返回！！ 燕 // Done - } else if (imm != nullptr && imm->Get(lkey, value, &s)) { + } else if (imm != nullptr && imm->Get(lkey, value, &s)) { //memtable没有，去imm找！！ 燕 // Done } else { - s = current->Get(options, lkey, value, &stats); + s = current->Get(options, lkey, value, &stats); //最后去sstable找！！燕 have_stat_update = true; } mutex_.Lock(); } if (have_stat_update && current->UpdateStats(stats)) { - MaybeScheduleCompaction(); + MaybeScheduleCompaction(); //如果有统计更新，则检查是否需要触发合并，燕 } mem->Unref(); if (imm != nullptr) imm->Unref(); - current->Unref(); - return s; + current->Unref(); //减少引用计数，允许释放内存 + return s; //返回状态对象 s，告知调用方是否成功找到值 } Iterator* DBImpl::NewIterator(const ReadOptions& options) { diff --git a/db/memtable.cc b/db/memtable.cc index 4f09340..f237ab5 100644 --- a/db/memtable.cc +++ b/db/memtable.cc @@ -8,6 +8,7 @@ #include "leveldb/env.h" #include "leveldb/iterator.h" #include "util/coding.h" +#include "include/leveldb/write_batch.h" namespace leveldb { @@ -99,40 +100,107 @@ void MemTable::Add(SequenceNumber s, ValueType type, const Slice& key, table_.Insert(buf); } +// bool MemTable::Get(const LookupKey& key, std::string* value, Status* s) { //燕改 +// Slice memkey = key.memtable_key(); +// Table::Iterator iter(&table_); +// iter.Seek(memkey.data()); +// if (iter.Valid()) {// 获取跳表项的内容 +// // entry format is: +// // klength varint32 +// // userkey char[klength] +// // tag uint64 +// // vlength varint32 +// // value char[vlength] +// // Check that it belongs to same user key. We do not check the +// // sequence number since the Seek() call above should have skipped +// // all entries with overly large sequence numbers. +// const char* entry = iter.key(); +// uint32_t key_length; +// const char* key_ptr = GetVarint32Ptr(entry, entry + 5, &key_length); +// if (comparator_.comparator.user_comparator()->Compare(// 比较键值 +// Slice(key_ptr, key_length - 8), key.user_key()) == 0) { +// // Correct user key +// const uint64_t tag = DecodeFixed64(key_ptr + key_length - 8); +// switch (static_cast(tag & 0xff)) { +// case kTypeValue: { +// // Slice v = GetLengthPrefixedSlice(key_ptr + key_length); +// // value->assign(v.data(), v.size()); +// // return true; + +// // 获取过期时间戳，燕改 +// Slice v = GetLengthPrefixedSlice(key_ptr + key_length); +// uint64_t expire_time = DecodeFixed64(v.data() + v.size() - sizeof(uint64_t)); + +// // 检查是否已过期 +// uint64_t current_time = Env::Default()->NowMicros() / 1000000; // 当前时间（秒） +// if (expire_time > 0 && expire_time < current_time) { +// *s = Status::NotFound("Key has expired"); // 已过期 +// return false; +// } + +// // 未过期，返回值 +// value->assign(v.data() + 8, v.size() - 8); // 去除前8字节的时间戳 +// return true; +// } +// case kTypeDeletion: +// *s = Status::NotFound(Slice()); +// return true; +// } +// } +// } +// return false; +// } + bool MemTable::Get(const LookupKey& key, std::string* value, Status* s) { - Slice memkey = key.memtable_key(); - Table::Iterator iter(&table_); - iter.Seek(memkey.data()); - if (iter.Valid()) { - // entry format is: - // klength varint32 - // userkey char[klength] - // tag uint64 - // vlength varint32 - // value char[vlength] - // Check that it belongs to same user key. We do not check the - // sequence number since the Seek() call above should have skipped - // all entries with overly large sequence numbers. - const char* entry = iter.key(); - uint32_t key_length; - const char* key_ptr = GetVarint32Ptr(entry, entry + 5, &key_length); - if (comparator_.comparator.user_comparator()->Compare( - Slice(key_ptr, key_length - 8), key.user_key()) == 0) { - // Correct user key - const uint64_t tag = DecodeFixed64(key_ptr + key_length - 8); - switch (static_cast(tag & 0xff)) { - case kTypeValue: { - Slice v = GetLengthPrefixedSlice(key_ptr + key_length); - value->assign(v.data(), v.size()); - return true; + Slice memkey = key.memtable_key(); + Table::Iterator iter(&table_); + iter.Seek(memkey.data()); + + if (iter.Valid()) { // 获取跳表项的内容 + const char* entry = iter.key(); + uint32_t key_length; + const char* key_ptr = GetVarint32Ptr(entry, entry + 5, &key_length); + + if (comparator_.comparator.user_comparator()->Compare( + Slice(key_ptr, key_length - 8), key.user_key()) == 0) { + const uint64_t tag = DecodeFixed64(key_ptr + key_length - 8); + switch (static_cast(tag & 0xff)) { + case kTypeValue: { + // 获取存储的值和时间戳 + Slice v = GetLengthPrefixedSlice(key_ptr + key_length); + std::string combined_str(v.data(), v.size()); + + // 根据存储格式分离原始值和时间戳 + std::string actual_value = combined_str.substr(0, combined_str.size() - 20); + std::string time_str = combined_str.substr(combined_str.size() - 19, 19); + + // 获取当前时间（字符串格式） + auto now = std::chrono::system_clock::now(); + auto now_time_t = std::chrono::system_clock::to_time_t(now); + std::tm* now_tm = std::localtime(&now_time_t); + char buffer[20]; + std::strftime(buffer, sizeof(buffer), "%Y-%m-%d %H:%M:%S", now_tm); + std::string current_time_str(buffer); + + // 检查过期 + if (time_str <= current_time_str) { + *s = Status::NotFound("Key has expired"); // 已过期 + return true; + } + + // 未过期，返回实际值 + value->assign(actual_value); + return true; + } + case kTypeDeletion: + *s = Status::NotFound(Slice()); + return true; + } } - case kTypeDeletion: - *s = Status::NotFound(Slice()); - return true; - } } - } - return false; + return false; } + + } // namespace leveldb diff --git a/db/memtable.h b/db/memtable.h index 9d986b1..f1e0cc9 100644 --- a/db/memtable.h +++ b/db/memtable.h @@ -60,6 +60,7 @@ class MemTable { // If memtable contains a deletion for key, store a NotFound() error // in *status and return true. // Else, return false. + std::chrono::system_clock::time_point insert_time; // 保存上次插入的时间，燕改 bool Get(const LookupKey& key, std::string* value, Status* s); private: diff --git a/db/write_batch.cc b/db/write_batch.cc index 061c2c3..bce2981 100644 --- a/db/write_batch.cc +++ b/db/write_batch.cc @@ -23,6 +23,7 @@ #include // For std::ostringstream 心 #include // 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. @@ -104,17 +105,34 @@ void WriteBatch::Put(const Slice& key, const Slice& value) { 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(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(&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(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); diff --git a/test/ttl_test.cc b/test/ttl_test.cc index 05ea42a..ba20598 100644 --- a/test/ttl_test.cc +++ b/test/ttl_test.cc @@ -20,11 +20,11 @@ Status OpenDB(std::string dbName, DB **db) { void InsertData(DB *db, uint64_t ttl/* second */) { WriteOptions writeOptions; int key_num = data_size / value_size; - srand(static_cast(time(0))); + srand(0); for (int i = 0; i < key_num; i++) { - //int key_ = rand() % key_num+1; - int key_ = i % key_num+1; + int key_ = rand() % key_num+1; + // int key_ = i % key_num+1; std::string key = std::to_string(key_); std::string value(value_size, 'a'); db->Put(writeOptions, key, value, ttl); @@ -36,7 +36,8 @@ void GetData(DB *db, int size = (1 << 30)) { int key_num = data_size / value_size; // 使用随机种子生成随机键进行点查（单次查询），燕 - srand(static_cast(time(0))); + // 点查 + srand(0); for (int i = 0; i < 100; i++) { int key_ = rand() % key_num+1; //int key_ = i % key_num+1; @@ -53,17 +54,17 @@ TEST(TestTTL, ReadTTL) { abort(); } - uint64_t ttl = 20; + uint64_t ttl = 200; InsertData(db, ttl); ReadOptions readOptions; Status status; int key_num = data_size / value_size; - srand(static_cast(time(0))); + srand(0); for (int i = 0; i < 100; i++) { - //int key_ = rand() % key_num+1; - int key_ = i % key_num+1; + int key_ = rand() % key_num+1; + // int key_ = i % key_num+1; std::string key = std::to_string(key_); std::string value; status = db->Get(readOptions, key, &value);