db/builder.cc

@@ -30,8 +30,17 @@ Status BuildTable(const std::string& dbname, Env* env, const Options& options,
 
     TableBuilder* builder = new TableBuilder(options, file);
     meta->smallest.DecodeFrom(iter->key());
-    Slice key;
+    Slice key=iter->key();
+    // 小合并时检查ttl
+    time_t now = time(nullptr); // 获得当前时间
+    uint64_t now_time=static_cast<uint64_t>(now);
     for (; iter->Valid(); iter->Next()) {
+      uint64_t ttl=*(uint64_t*)(iter->value().data()+iter->value().size()-sizeof(uint64_t)); // 将 TTL 从 new_data 的末尾取出
+      // 如果 TTL 超过当前时间，说明数据已经过期
+      if(ttl < static_cast<uint64_t>(now_time)){
+        continue;
+      }
+          
       key = iter->key();
       builder->Add(key, iter->value());
     }

db/db_impl.cc

@@ -57,6 +57,8 @@ struct DBImpl::CompactionState {
     uint64_t number;
     uint64_t file_size;
     InternalKey smallest, largest;
+    // uint64_t now = static_cast<uint64_t>(time(nullptr)); // 合并发起的时间
+
   };
 
   Output* current_output() { return &outputs[outputs.size() - 1]; }
@@ -923,12 +925,13 @@ Status DBImpl::DoCompactionWork(CompactionState* compact) {
   std::string current_user_key;
   bool has_current_user_key = false;
   SequenceNumber last_sequence_for_key = kMaxSequenceNumber;
+  time_t now = time(nullptr); // 获得当前时间
+  uint64_t now_time=static_cast<uint64_t>(now);
   while (input->Valid() && !shutting_down_.load(std::memory_order_acquire)) {
     auto x=input->value(); // 获取键值对 value
     uint64_t ttl=*(uint64_t*)(x.data()+x.size()-sizeof(uint64_t));// 将 TTL 从 new_data 的末尾取出
-    time_t now = time(nullptr); // 获得当前时间
     // 如果 TTL 超过当前时间，说明数据已经过期
-    if(ttl < static_cast<uint64_t>(now)){
+    if(ttl < now_time){
       Log(options_.info_log, "delete record for ttl");
       input->Next(); // 将 input 指向下一个键值对
       continue;

test/ttl_test.cc

@@ -65,7 +65,7 @@ TEST(TestTTL, ReadTTL) {
         ASSERT_TRUE(status.ok());
     }
 
-    Env::Default()->SleepForMicroseconds((ttl+1) * 1000000);
+    Env::Default()->SleepForMicroseconds((ttl+2) * 1000000);
 
     for (int i = 0; i < 100; i++) {
         int key_ = rand() % key_num+1;