对于过期导致的value不命中，多减少一次allowed_seek的次数

db/db_impl.cc

@@ -1178,18 +1178,24 @@ Status DBImpl::Get(const ReadOptions& options, const Slice& key,
     }
     mutex_.Lock();
   }
-
-  if (have_stat_update && current->UpdateStats(stats)) {
+  if(s.ok()){
+    s = CheckIsExpire(value);
+  }
+  if (have_stat_update && current->UpdateStats(stats,s.IsExpire())) {
     MaybeScheduleCompaction();//有可能寻址过多，导致allow_seek为0，触发合并。
   }
   mem->Unref();
   if (imm != nullptr) imm->Unref();
+
   current->Unref();
-  if(!s.ok()){
-    return s;
-  }
-  auto s2 = CheckIsExpire(value);
-  return s2;
+//  if(!s.ok()){
+//    return s;
+//  }
+//  auto s2 = CheckIsExpire(value);
+//  if(!s2.ok()){
+//    current->UpdateStats(stats);
+//  }
+  return s;
 }
 
 Iterator* DBImpl::NewIterator(const ReadOptions& options) {
@@ -1229,21 +1235,6 @@ Status DBImpl::Put(const WriteOptions& o, const Slice& key, const Slice& val) {
 
 Status DBImpl::Put(const WriteOptions& options, const Slice& key,
                    const Slice& value, uint64_t ttl) {
-  //rocksdb的实现
-//  Status DBWithTTLImpl::AppendTS(const Slice& val, std::string* val_with_ts,
-//                                 SystemClock* clock) {
-//    val_with_ts->reserve(kTSLength + val.size());
-//    char ts_string[kTSLength];
-//    int64_t curtime;
-//    Status st = clock->GetCurrentTime(&curtime);
-//    if (!st.ok()) {
-//      return st;
-//    }
-//    EncodeFixed32(ts_string, (int32_t)curtime);
-//    val_with_ts->append(val.data(), val.size());
-//    val_with_ts->append(ts_string, kTSLength);
-//    return st;
-//  }
 
   std::string val_with_ts;
   val_with_ts.reserve(value.size() + kTSLength);
@@ -1256,12 +1247,6 @@ Status DBImpl::Put(const WriteOptions& options, const Slice& key,
 
   // 将 expiration_time 追加到 val_with_ts
   val_with_ts.append(ts_string,kTSLength);
-//  std::cout << "val_with_ts in hex: ";
-//  for (unsigned char c : val_with_ts) {
-//    std::cout << std::hex << std::setw(2) << std::setfill('0') << (int)c << " ";
-//  }
-//  std::cout << std::endl;
-
   return DB::Put(options, key, Slice(val_with_ts));
 }
 
@@ -1569,45 +1554,24 @@ void DBImpl::AppendTS(const Slice& val, std::string* val_with_ts,uint64_t ttl) {
  * @return timestamp in val,and remove timestamp from val
  */
 uint64_t DBImpl::GetTS(std::string* val) {
-    //uint64_t expiration_time;
-    // 输出 val 的十六进制表示
-//    std::cout << "befor decode,val in hex: ";
-//    for (unsigned char c : *val) {
-//      std::cout << std::hex << std::setw(2) << std::setfill('0') << (int)c << " ";
-//    }
-//    std::cout << std::endl;
+
     auto expiration_time =  DecodeFixed64(val->data() + val->size() - kTSLength);
-    //memcpy(&expiration_time, val->data() + val->size() - sizeof(TIMESTAMP), sizeof(TIMESTAMP));
+
     val->resize(val->size() - kTSLength);
-//    std::cout << "after decode,val in hex: ";
-//    for (unsigned char c : *val) {
-//      std::cout << std::hex << std::setw(2) << std::setfill('0') << (int)c << " ";
-//    }
-//    std::cout << std::endl;
+
     return expiration_time;
 
-//    Status DBWithTTLImpl::StripTS(PinnableSlice* pinnable_val) {
-//      if (pinnable_val->size() < kTSLength) {
-//        return Status::Corruption("Bad timestamp in key-value");
-//      }
-//      // Erasing characters which hold the TS
-//      pinnable_val->remove_suffix(kTSLength);
-//      return Status::OK();
-//    }
 }
 Status DBImpl::CheckIsExpire(std::string* value) {
   //debug 用
   auto a = env_->NowMicros();
   auto b = GetTS(value);
-//  std::cout<<"get current time"<<a<<std::endl;
-//  std::cout << "get ts from val"<<b<<std::endl;
+
   if(a > b){
     return Status::Expire("Expire",Slice());
   }
   return Status();
-//  if(env_->GetCurrentTime() > GetTS(value)){
-//    return Status::Expire("Expire",Slice());
-//  }
+
 }
 
 /**

db/version_set.cc

@@ -413,6 +413,20 @@ bool Version::UpdateStats(const GetStats& stats) {
   return false;
 }
 
+bool Version::UpdateStats(const GetStats& stats,bool is_expire) {
+  FileMetaData* f = stats.seek_file;
+  if (f != nullptr) {
+    f->allowed_seeks--;
+    if(is_expire)f->allowed_seeks--;
+    if (f->allowed_seeks <= 0 && file_to_compact_ == nullptr) {
+      file_to_compact_ = f;
+      file_to_compact_level_ = stats.seek_file_level;
+      return true;
+    }
+  }
+  return false;
+}
+
 bool Version::RecordReadSample(Slice internal_key) {
   ParsedInternalKey ikey;
   if (!ParseInternalKey(internal_key, &ikey)) {
@@ -821,7 +835,7 @@ Status VersionSet::LogAndApply(VersionEdit* edit, port::Mutex* mu) {
     // Write new record to MANIFEST log
     if (s.ok()) {
       std::string record;
-      edit->EncodeTo(&record);// TODO:修改
+      edit->EncodeTo(&record);
       s = descriptor_log_->AddRecord(record);
       if (s.ok()) {
         s = descriptor_file_->Sync();

db/version_set.h

@@ -80,8 +80,8 @@ class Version {
   // compaction may need to be triggered, false otherwise.
   // REQUIRES: lock is held
   bool UpdateStats(const GetStats& stats);
-
-  // Record a sample of bytes read at the specified internal key.
+  bool UpdateStats(const GetStats& stats,bool is_expire);
+      // Record a sample of bytes read at the specified internal key.
   // Samples are taken approximately once every config::kReadBytesPeriod
   // bytes.  Returns true if a new compaction may need to be triggered.
   // REQUIRES: lock is held
@@ -313,7 +313,7 @@ class VersionSet {
 
   // Per-level key at which the next compaction at that level should start.
   // Either an empty string, or a valid InternalKey.
-  std::string compact_pointer_[config::kNumLevels];
+  std::string compact_pointer_[config::kNumLevels];//会在完成一次压缩操作后进行更新，以确保下一次压缩不会总是从相同的地方
 };
 
 // A Compaction encapsulates information about a compaction.

include/leveldb/status.h

@@ -74,6 +74,7 @@ class LEVELDB_EXPORT Status {
   // Returns true iff the status indicates an InvalidArgument.
   bool IsInvalidArgument() const { return code() == kInvalidArgument; }
 
+  bool IsExpire()const{return code() == kExpire;}
   // Return a string representation of this status suitable for printing.
   // Returns the string "OK" for success.
   std::string ToString() const;

test/ttl_test.cc

@@ -75,33 +75,33 @@ TEST(TestTTL, ReadTTL) {
   Env::Default()->SleepForMicroseconds( 1000);
 }
 
-//TEST(TestTTL, CompactionTTL) {
-//  DestroyDB("testdb", Options());
-//  DB *db;
-//  if(OpenDB("testdb", &db).ok() == false) {
-//    std::cerr << "open db failed" << std::endl;
-//    abort();
-//  }
-//
-//  uint64_t ttl = 20;
-//  InsertData(db, ttl);
-//
-//  leveldb::Range ranges[1];
-//  ranges[0] = leveldb::Range("-", "A");
-//  uint64_t sizes[1];
-//  db->GetApproximateSizes(ranges, 1, sizes);
-//  ASSERT_GT(sizes[0], 0);
-//
-//  Env::Default()->SleepForMicroseconds(ttl * 1000000);
-//
-//  db->CompactRange(nullptr, nullptr);
-//
-//  leveldb::Range ranges2[1];
-//  ranges2[0] = leveldb::Range("-", "A");
-//  uint64_t sizes2[1];
-//  db->GetApproximateSizes(ranges2, 1, sizes2);
-//  ASSERT_EQ(sizes2[0], 0);
-//}
+TEST(TestTTL, CompactionTTL) {
+  DestroyDB("testdb", Options());
+  DB *db;
+  if(OpenDB("testdb", &db).ok() == false) {
+    std::cerr << "open db failed" << std::endl;
+    abort();
+  }
+
+  uint64_t ttl = 20;
+  InsertData(db, ttl);
+
+  leveldb::Range ranges[1];
+  ranges[0] = leveldb::Range("-", "A");
+  uint64_t sizes[1];
+  db->GetApproximateSizes(ranges, 1, sizes);
+  ASSERT_GT(sizes[0], 0);
+
+  Env::Default()->SleepForMicroseconds(ttl * 1000000);
+
+  db->CompactRange(nullptr, nullptr);
+
+  leveldb::Range ranges2[1];
+  ranges2[0] = leveldb::Range("-", "A");
+  uint64_t sizes2[1];
+  db->GetApproximateSizes(ranges2, 1, sizes2);
+  ASSERT_EQ(sizes2[0], 0);
+}
 
 
 int main(int argc, char** argv) {