CMakeLists.txt

@@ -524,6 +524,10 @@ add_executable(db_test2
 )
 target_link_libraries(db_test2 PRIVATE leveldb)
 
+add_executable(ttl_mmtable_test
+        "${PROJECT_SOURCE_DIR}/test/ttl_mmtable_test.cc"
+)
+target_link_libraries(ttl_mmtable_test PRIVATE leveldb)
 
 add_executable(ttl_test
         "${PROJECT_SOURCE_DIR}/test/ttl_test.cc"

db/c.cc

@@ -349,7 +349,7 @@ void leveldb_writebatch_iterate(const leveldb_writebatch_t* b, void* state,
     void* state_;
     void (*put_)(void*, const char* k, size_t klen, const char* v, size_t vlen);
     void (*deleted_)(void*, const char* k, size_t klen);
-    void Put(const Slice& key, const Slice& value) override {
+    void Put(const Slice& key, const Slice& value, uint64_t deadTime) override {
       (*put_)(state_, key.data(), key.size(), value.data(), value.size());
     }
     void Delete(const Slice& key) override {

db/db_impl.cc

@@ -1143,12 +1143,19 @@ 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);
+    time_t nowTime;
+    time(&nowTime);
+    assert(nowTime > 0);
+
+    LookupKey lkey(key, snapshot, nowTime);
     if (mem->Get(lkey, value, &s)) {
+      printf("in mem\n");
       // Done
     } else if (imm != nullptr && imm->Get(lkey, value, &s)) {
+      printf("in immem\n");
       // Done
     } else {
+      printf("in current\n");
       s = current->Get(options, lkey, value, &stats);
       have_stat_update = true;
     }
@@ -1194,8 +1201,9 @@ void DBImpl::ReleaseSnapshot(const Snapshot* snapshot) {
 }
 
 // Convenience methods
-Status DBImpl::Put(const WriteOptions& o, const Slice& key, const Slice& val) {
-  return DB::Put(o, key, val);
+Status DBImpl::Put(const WriteOptions& o, const Slice& key, 
+                  const Slice& val, uint64_t ttl) {
+  return DB::Put(o, key, val, ttl);
 }
 
 Status DBImpl::Delete(const WriteOptions& options, const Slice& key) {
@@ -1232,7 +1240,7 @@ Status DBImpl::Write(const WriteOptions& options, WriteBatch* updates) {
     // into mem_.
     {
       mutex_.Unlock();
-      status = log_->AddRecord(WriteBatchInternal::Contents(write_batch));
+      status = log_->AddRecord(WriteBatchInternal::Contents(write_batch)); //这里会有影响吗
       bool sync_error = false;
       if (status.ok() && options.sync) {
         status = logfile_->Sync();
@@ -1485,9 +1493,10 @@ void DBImpl::GetApproximateSizes(const Range* range, int n, uint64_t* sizes) {
 
 // Default implementations of convenience methods that subclasses of DB
 // can call if they wish
-Status DB::Put(const WriteOptions& opt, const Slice& key, const Slice& value) {
+Status DB::Put(const WriteOptions& opt, const Slice& key, 
+              const Slice& value, uint64_t ttl) {
   WriteBatch batch;
-  batch.Put(key, value);
+  batch.Put(key, value, ttl);
   return Write(opt, &batch);
 }
 

db/db_impl.h

@@ -37,7 +37,7 @@ class DBImpl : public DB {
 
   // Implementations of the DB interface
   Status Put(const WriteOptions&, const Slice& key,
-             const Slice& value) override;
+             const Slice& value, uint64_t ttl) override;
   Status Delete(const WriteOptions&, const Slice& key) override;
   Status Write(const WriteOptions& options, WriteBatch* updates) override;
   Status Get(const ReadOptions& options, const Slice& key,

db/db_test.cc

@@ -2114,8 +2114,8 @@ class ModelDB : public DB {
 
   explicit ModelDB(const Options& options) : options_(options) {}
   ~ModelDB() override = default;
-  Status Put(const WriteOptions& o, const Slice& k, const Slice& v) override {
-    return DB::Put(o, k, v);
+  Status Put(const WriteOptions& o, const Slice& k, const Slice& v, uint64_t ttl = 0) override {
+    return DB::Put(o, k, v, ttl);
   }
   Status Delete(const WriteOptions& o, const Slice& key) override {
     return DB::Delete(o, key);
@@ -2149,7 +2149,7 @@ class ModelDB : public DB {
     class Handler : public WriteBatch::Handler {
      public:
       KVMap* map_;
-      void Put(const Slice& key, const Slice& value) override {
+      void Put(const Slice& key, const Slice& value, uint64_t deadTime = 0) override {
         (*map_)[key.ToString()] = value.ToString();
       }
       void Delete(const Slice& key) override { map_->erase(key.ToString()); }

db/dbformat.cc

@@ -12,6 +12,14 @@
 
 namespace leveldb {
 
+static uint64_t PackSequenceAndTypeAndTtlAndLookup(
+                      uint64_t seq, ValueType t, bool havettl, bool islookup) {
+  assert(seq <= kMaxSequenceNumber);
+  assert(t <= kValueTypeForSeek);
+  return (seq << 8) | (islookup << 2) | (havettl << 1) | t;
+}
+
+//下面有两个调这个函数的没改，也许也要修改标志位？
 static uint64_t PackSequenceAndType(uint64_t seq, ValueType t) {
   assert(seq <= kMaxSequenceNumber);
   assert(t <= kValueTypeForSeek);
@@ -20,7 +28,10 @@ static uint64_t PackSequenceAndType(uint64_t seq, ValueType t) {
 
 void AppendInternalKey(std::string* result, const ParsedInternalKey& key) {
   result->append(key.user_key.data(), key.user_key.size());
-  PutFixed64(result, PackSequenceAndType(key.sequence, key.type));
+  if(key.deadTime != 0)
+    PutFixed64(result, key.deadTime);
+  PutFixed64(result, PackSequenceAndTypeAndTtlAndLookup(
+                                key.sequence, key.type, (key.deadTime != 0), false));
 }
 
 std::string ParsedInternalKey::DebugString() const {
@@ -49,13 +60,33 @@ int InternalKeyComparator::Compare(const Slice& akey, const Slice& bkey) const {
   //    increasing user key (according to user-supplied comparator)
   //    decreasing sequence number
   //    decreasing type (though sequence# should be enough to disambiguate)
+  //目前看调用时都是a为node, b为key，万一有不是的，逻辑还得补充
+  //for debug
+  // std::string a = ExtractUserKey(akey).ToString();
+  // std::string b = ExtractUserKey(bkey).ToString();
   int r = user_comparator_->Compare(ExtractUserKey(akey), ExtractUserKey(bkey));
   if (r == 0) {
-    const uint64_t anum = DecodeFixed64(akey.data() + akey.size() - 8);
-    const uint64_t bnum = DecodeFixed64(bkey.data() + bkey.size() - 8);
-    if (anum > bnum) {
+    const uint64_t atag = DecodeFixed64(akey.data() + akey.size() - 8);
+    const uint64_t btag = DecodeFixed64(bkey.data() + bkey.size() - 8);
+
+    const uint64_t aseq = atag >> 8;
+    const uint64_t bseq = btag >> 8;   
+    if (aseq > bseq) {
+      r = -1;
+      return r;
+    }
+    
+    //原本应该找到了，新加判断
+    if((btag & 0b100) && (atag & 0b10)){ //一个是查询键，另一个有ttl
+      const uint64_t atime = DecodeFixed64(akey.data() + akey.size() - 16);
+      const uint64_t btime = DecodeFixed64(bkey.data() + bkey.size() - 16);
+      if(atime <= btime){//过期了继续找
         r = -1;
-    } else if (anum < bnum) {
+        return r;
+      }
+    }
+    
+    if (aseq < bseq) {
       r = +1;
     }
   }
@@ -114,9 +145,9 @@ bool InternalFilterPolicy::KeyMayMatch(const Slice& key, const Slice& f) const {
   return user_policy_->KeyMayMatch(ExtractUserKey(key), f);
 }
 
-LookupKey::LookupKey(const Slice& user_key, SequenceNumber s) {
+LookupKey::LookupKey(const Slice& user_key, SequenceNumber s, uint64_t nowTime) {
   size_t usize = user_key.size();
-  size_t needed = usize + 13;  // A conservative estimate
+  size_t needed = usize + 21;  // A conservative estimate
   char* dst;
   if (needed <= sizeof(space_)) {
     dst = space_;
@@ -124,11 +155,13 @@ LookupKey::LookupKey(const Slice& user_key, SequenceNumber s) {
     dst = new char[needed];
   }
   start_ = dst;
-  dst = EncodeVarint32(dst, usize + 8);
+  dst = EncodeVarint32(dst, usize + 16);
   kstart_ = dst;
   std::memcpy(dst, user_key.data(), usize);
   dst += usize;
-  EncodeFixed64(dst, PackSequenceAndType(s, kValueTypeForSeek));
+  EncodeFixed64(dst, nowTime);
+  dst += 8;
+  EncodeFixed64(dst, PackSequenceAndTypeAndTtlAndLookup(s, kValueTypeForSeek, 0, true));
   dst += 8;
   end_ = dst;
 }

db/dbformat.h

@@ -16,6 +16,7 @@
 #include "leveldb/table_builder.h"
 #include "util/coding.h"
 #include "util/logging.h"
+#include "iostream"
 
 namespace leveldb {
 
@@ -69,17 +70,19 @@ static const SequenceNumber kMaxSequenceNumber = ((0x1ull << 56) - 1);
 struct ParsedInternalKey {
   Slice user_key;
   SequenceNumber sequence;
+  uint64_t deadTime;  
   ValueType type;
 
   ParsedInternalKey() {}  // Intentionally left uninitialized (for speed)
-  ParsedInternalKey(const Slice& u, const SequenceNumber& seq, ValueType t)
-      : user_key(u), sequence(seq), type(t) {}
+  ParsedInternalKey(const Slice& u, const SequenceNumber& seq, 
+                    ValueType t, uint64_t d = 0)
+      : user_key(u), sequence(seq), type(t), deadTime(d) {}
   std::string DebugString() const;
 };
 
 // Return the length of the encoding of "key".
 inline size_t InternalKeyEncodingLength(const ParsedInternalKey& key) {
-  return key.user_key.size() + 8;
+  return key.user_key.size() + 8 + (key.deadTime != 0) * 8;
 }
 
 // Append the serialization of "key" to *result.
@@ -94,7 +97,13 @@ bool ParseInternalKey(const Slice& internal_key, ParsedInternalKey* result);
 // Returns the user key portion of an internal key.
 inline Slice ExtractUserKey(const Slice& internal_key) {
   assert(internal_key.size() >= 8);
-  return Slice(internal_key.data(), internal_key.size() - 8);
+  uint64_t num = DecodeFixed64(internal_key.data() + internal_key.size() - 8);
+  uint8_t havettl = (num & 0b10) >> 1;
+  uint8_t islookup = (num & 0b100) >> 2;
+  size_t klen = internal_key.size() - 8;
+  if(havettl || islookup)  klen -= 8;
+  Slice user_key = Slice(internal_key.data(), klen);
+  return user_key;
 }
 
 // A comparator for internal keys that uses a specified comparator for
@@ -137,8 +146,9 @@ class InternalKey {
 
  public:
   InternalKey() {}  // Leave rep_ as empty to indicate it is invalid
-  InternalKey(const Slice& user_key, SequenceNumber s, ValueType t) {
-    AppendInternalKey(&rep_, ParsedInternalKey(user_key, s, t));
+  InternalKey(const Slice& user_key, SequenceNumber s, 
+              ValueType t, uint64_t deadTime = 0) {
+    AppendInternalKey(&rep_, ParsedInternalKey(user_key, s, t, deadTime));
   }
 
   bool DecodeFrom(const Slice& s) {
@@ -170,13 +180,21 @@ inline int InternalKeyComparator::Compare(const InternalKey& a,
 
 inline bool ParseInternalKey(const Slice& internal_key,
                              ParsedInternalKey* result) {
+                              //不确定需不需要标识islookup，先没改
   const size_t n = internal_key.size();
   if (n < 8) return false;
-  uint64_t num = DecodeFixed64(internal_key.data() + n - 8);
-  uint8_t c = num & 0xff;
-  result->sequence = num >> 8;
-  result->type = static_cast<ValueType>(c);
+  uint64_t tag = DecodeFixed64(internal_key.data() + n - 8);
+  uint8_t c = tag & 0xff;
+  uint8_t havettl = (c & 0b10) >> 1;
+  result->sequence = tag >> 8;
+  result->type = static_cast<ValueType>(c & 0b1);
+  if(havettl){
+    result->deadTime = DecodeFixed64(internal_key.data() + n - 16);
+    result->user_key = Slice(internal_key.data(), n - 16);
+  } else {
+    result->deadTime = 0;    
     result->user_key = Slice(internal_key.data(), n - 8);
+  }
   return (c <= static_cast<uint8_t>(kTypeValue));
 }
 
@@ -185,7 +203,7 @@ class LookupKey {
  public:
   // Initialize *this for looking up user_key at a snapshot with
   // the specified sequence number.
-  LookupKey(const Slice& user_key, SequenceNumber sequence);
+  LookupKey(const Slice& user_key, SequenceNumber sequence, uint64_t nowTime);
 
   LookupKey(const LookupKey&) = delete;
   LookupKey& operator=(const LookupKey&) = delete;
@@ -199,14 +217,17 @@ class LookupKey {
   Slice internal_key() const { return Slice(kstart_, end_ - kstart_); }
 
   // Return the user key
-  Slice user_key() const { return Slice(kstart_, end_ - kstart_ - 8); }
+  Slice user_key() const { return Slice(kstart_, end_ - kstart_ - 16); }
 
  private:
   // We construct a char array of the form:
   //    klength  varint32               <-- start_
   //    userkey  char[klength]          <-- kstart_
-  //    tag      uint64
+  //    nowTime  uint64
+  //    tag      uint64 最后一个字节为0000 0101
   //                                    <-- end_
+  //    同userkey下，原本（insert时）的比较器规则为seq优先，不考虑时间
+  //    新增标识位（tag倒数第三位），使比较器考虑时间
   // The array is a suitable MemTable key.
   // The suffix starting with "userkey" can be used as an InternalKey.
   const char* start_;

db/dumpfile.cc

@@ -74,7 +74,7 @@ Status PrintLogContents(Env* env, const std::string& fname,
 // Called on every item found in a WriteBatch.
 class WriteBatchItemPrinter : public WriteBatch::Handler {
  public:
-  void Put(const Slice& key, const Slice& value) override {
+  void Put(const Slice& key, const Slice& value, uint64_t deadTime) override {
     std::string r = "  put '";
     AppendEscapedStringTo(&r, key);
     r += "' '";

db/memtable.cc

@@ -8,6 +8,8 @@
 #include "leveldb/env.h"
 #include "leveldb/iterator.h"
 #include "util/coding.h"
+#include "ctime"
+#include "iostream"
 
 namespace leveldb {
 
@@ -74,16 +76,24 @@ class MemTableIterator : public Iterator {
 Iterator* MemTable::NewIterator() { return new MemTableIterator(&table_); }
 
 void MemTable::Add(SequenceNumber s, ValueType type, const Slice& key,
-                   const Slice& value) {
+                   const Slice& value, uint64_t deadTime) {
   // Format of an entry is concatenation of:
   //  key_size     : varint32 of internal_key.size()
   //  key bytes    : char[internal_key.size()]
   //  tag          : uint64((sequence << 8) | type)
   //  value_size   : varint32 of value.size()
   //  value bytes  : char[value.size()]
+  //变成
+  //  key_size     : varint32 of internal_key.size()
+  //  key bytes    : char[internal_key.size()]
+  // (deadTime)    : uint64(可能有)
+  //  tag          : uint64((sequence << 8) | havettl << 1 | type)
+  //  value_size   : varint32 of value.size()
+  //  value bytes  : char[value.size()]
   size_t key_size = key.size();
   size_t val_size = value.size();
   size_t internal_key_size = key_size + 8;
+  if(deadTime != 0) internal_key_size += 8;
   const size_t encoded_len = VarintLength(internal_key_size) +
                              internal_key_size + VarintLength(val_size) +
                              val_size;
@@ -91,22 +101,33 @@ void MemTable::Add(SequenceNumber s, ValueType type, const Slice& key,
   char* p = EncodeVarint32(buf, internal_key_size);
   std::memcpy(p, key.data(), key_size);
   p += key_size;
+  
+  if(deadTime == 0){
     EncodeFixed64(p, (s << 8) | type);
+  } else {
+    EncodeFixed64(p, deadTime);
     p += 8;
+    EncodeFixed64(p, (s << 8) | 0b10 | type);
+  }
+  p += 8;
+
   p = EncodeVarint32(p, val_size);
   std::memcpy(p, value.data(), val_size);
   assert(p + val_size == buf + encoded_len);
   table_.Insert(buf);
+  std::cout << "insert:" << key.ToString() << std::endl;
 }
 
 bool MemTable::Get(const LookupKey& key, std::string* value, Status* s) {
   Slice memkey = key.memtable_key();
   Table::Iterator iter(&table_);
   iter.Seek(memkey.data());
+  std::cout << "search:" << key.user_key().ToString() << " valid?" << iter.Valid();
   if (iter.Valid()) {
     // entry format is:
     //    klength  varint32
     //    userkey  char[klength]
+    //    (deadTime) uint64
     //    tag      uint64
     //    vlength  varint32
     //    value    char[vlength]
@@ -116,12 +137,26 @@ bool MemTable::Get(const LookupKey& key, std::string* value, Status* s) {
     const char* entry = iter.key();
     uint32_t key_length;
     const char* key_ptr = GetVarint32Ptr(entry, entry + 5, &key_length);
+
+    std::cout << " get:" << ExtractUserKey(Slice(key_ptr, key_length)).ToString() << std::endl;
     if (comparator_.comparator.user_comparator()->Compare(
-            Slice(key_ptr, key_length - 8), key.user_key()) == 0) {
+            ExtractUserKey(Slice(key_ptr, key_length)), key.user_key()) == 0) {
       // Correct user key
       const uint64_t tag = DecodeFixed64(key_ptr + key_length - 8);
-      switch (static_cast<ValueType>(tag & 0xff)) {
+      switch (static_cast<ValueType>(tag & 0x01)) {
         case kTypeValue: {
+          // uint8_t havettl = (tag & 0xff) >> 1;
+          // if(havettl){
+          //     time_t nowTime;
+          //     time(&nowTime);
+          //     assert(nowTime > 0);
+          //     const uint64_t deadTime = DecodeFixed64(key_ptr + key_length - 16);
+          //     if(static_cast<uint64_t>(nowTime) >= deadTime){ //过期了
+          //       std::cout << nowTime << "dead:" << deadTime << std::endl;
+          //       *s = Status::NotFound(Slice());
+          //       return true; //todo:之前有没过期的key
+          //     }
+          // }
           Slice v = GetLengthPrefixedSlice(key_ptr + key_length);
           value->assign(v.data(), v.size());
           return true;

db/memtable.h

@@ -54,7 +54,7 @@ class MemTable {
   // specified sequence number and with the specified type.
   // Typically value will be empty if type==kTypeDeletion.
   void Add(SequenceNumber seq, ValueType type, const Slice& key,
-           const Slice& value);
+           const Slice& value, uint64_t deadTime = 0);
 
   // If memtable contains a value for key, store it in *value and return true.
   // If memtable contains a deletion for key, store a NotFound() error

db/write_batch.cc

@@ -6,13 +6,20 @@
 //    sequence: fixed64
 //    count: fixed32
 //    data: record[count]
-// record :=
+// 原来record := 
 //    kTypeValue varstring varstring         |
 //    kTypeDeletion varstring
 // varstring :=
 //    len: varint32
 //    data: uint8[len]
 
+// 增加ttl后record := 
+//    kTypeValue havettl (deadtime) varstring  varstring         |
+//    kTypeDeletion varstring
+// varstring :=
+//    len: varint32
+//    data: uint8[len]
+
 #include "leveldb/write_batch.h"
 
 #include "db/dbformat.h"
@@ -20,6 +27,8 @@
 #include "db/write_batch_internal.h"
 #include "leveldb/db.h"
 #include "util/coding.h"
+#include "ctime"
+#include <cstdint>
 
 namespace leveldb {
 
@@ -54,12 +63,22 @@ Status WriteBatch::Iterate(Handler* handler) const {
     input.remove_prefix(1);
     switch (tag) {
       case kTypeValue:
+        {
+        char havettl = input[0];
+        input.remove_prefix(1);
+        uint64_t deadTime = 0;
+        if(havettl){
+          deadTime = DecodeFixed64(input.data());
+          input.remove_prefix(8);
+        }
+
         if (GetLengthPrefixedSlice(&input, &key) &&
             GetLengthPrefixedSlice(&input, &value)) {
-          handler->Put(key, value);
+          handler->Put(key, value, deadTime);
         } else {
           return Status::Corruption("bad WriteBatch Put");
         }
+        }
         break;
       case kTypeDeletion:
         if (GetLengthPrefixedSlice(&input, &key)) {
@@ -95,9 +114,20 @@ void WriteBatchInternal::SetSequence(WriteBatch* b, SequenceNumber seq) {
   EncodeFixed64(&b->rep_[0], seq);
 }
 
-void WriteBatch::Put(const Slice& key, const Slice& value) {
+void WriteBatch::Put(const Slice& key, const Slice& value, uint64_t ttl) {
   WriteBatchInternal::SetCount(this, WriteBatchInternal::Count(this) + 1);
   rep_.push_back(static_cast<char>(kTypeValue));
+
+  rep_.push_back(static_cast<char>(ttl != 0)); //1:havettl
+  if(ttl != 0){
+      time_t nowTime;
+      time(&nowTime);
+      assert(nowTime > 0);
+      assert(ttl > 0);
+      uint64_t deadTime = static_cast<uint64_t>(nowTime) + ttl;
+      PutFixed64(&rep_, deadTime);
+  }
+
   PutLengthPrefixedSlice(&rep_, key);
   PutLengthPrefixedSlice(&rep_, value);
 }
@@ -118,12 +148,12 @@ class MemTableInserter : public WriteBatch::Handler {
   SequenceNumber sequence_;
   MemTable* mem_;
 
-  void Put(const Slice& key, const Slice& value) override {
-    mem_->Add(sequence_, kTypeValue, key, value);
+  void Put(const Slice& key, const Slice& value, uint64_t deadTime) override {
+    mem_->Add(sequence_, kTypeValue, key, value, deadTime);
     sequence_++;
   }
   void Delete(const Slice& key) override {
-    mem_->Add(sequence_, kTypeDeletion, key, Slice());
+    mem_->Add(sequence_, kTypeDeletion, key, Slice(), 0);
     sequence_++;
   }
 };

include/leveldb/db.h

@@ -63,8 +63,8 @@ class LEVELDB_EXPORT DB {
   // Set the database entry for "key" to "value".  Returns OK on success,
   // and a non-OK status on error.
   // Note: consider setting options.sync = true.
-  virtual Status Put(const WriteOptions& options, const Slice& key,
-                     const Slice& value) = 0;
+  // virtual Status Put(const WriteOptions& options, const Slice& key,
+  //                    const Slice& value) = 0;
 
   // Remove the database entry (if any) for "key".  Returns OK on
   // success, and a non-OK status on error.  It is not an error if "key"
@@ -149,7 +149,7 @@ class LEVELDB_EXPORT DB {
   // ----------------------------For TTL-----------------------------
   // 为当前key设置ttl，过期后自动失效
   virtual Status Put(const WriteOptions& options, const Slice& key,
-                     const Slice& value, uint64_t ttl) = 0;
+                     const Slice& value, uint64_t ttl = 0) = 0;
 };
 
 // Destroy the contents of the specified database.

include/leveldb/write_batch.h

@@ -25,6 +25,7 @@
 
 #include "leveldb/export.h"
 #include "leveldb/status.h"
+#include <cstdint>
 
 namespace leveldb {
 
@@ -35,7 +36,7 @@ class LEVELDB_EXPORT WriteBatch {
   class LEVELDB_EXPORT Handler {
    public:
     virtual ~Handler();
-    virtual void Put(const Slice& key, const Slice& value) = 0;
+    virtual void Put(const Slice& key, const Slice& value, uint64_t deadTime = 0) = 0;
     virtual void Delete(const Slice& key) = 0;
   };
 
@@ -48,7 +49,7 @@ class LEVELDB_EXPORT WriteBatch {
   ~WriteBatch();
 
   // Store the mapping "key->value" in the database.
-  void Put(const Slice& key, const Slice& value);
+  void Put(const Slice& key, const Slice& value, uint64_t ttl = 0);
 
   // If the database contains a mapping for "key", erase it.  Else do nothing.
   void Delete(const Slice& key);

test/ttl_mmtable_test.cc

@@ -0,0 +1,113 @@
+#include "leveldb/env.h"
+#include "leveldb/db.h"
+#include "ctime"
+#include <iostream>
+#include <cstdlib>
+#include "gtest/gtest.h"
+
+using namespace leveldb;
+
+constexpr int value_size = 2048;
+constexpr int data_size = 2048 << 2;
+
+Status OpenDB(std::string dbName, DB **db) {
+  Options options;
+  options.create_if_missing = true;
+  return DB::Open(options, dbName, db);
+}
+
+void InsertData(DB *db, uint64_t ttl/* second */, int vsize = 1/*插不同长度的value*/) {
+  printf("-----inserting-----\n");
+  Status status;
+  WriteOptions writeOptions;
+  int key_num = data_size / value_size;
+  srand(static_cast<unsigned int>(time(0)));
+
+  for (int i = 0; i < key_num; i++) {
+    //int key_ = rand() % key_num+1;
+    int key_ = i+1;
+    std::string key = std::to_string(key_);
+    std::string value(vsize, 'a');
+    status = db->Put(writeOptions, key, value, ttl);
+    assert(status.ok());
+  }
+}
+
+void GetData(DB *db, bool isTimeout) {
+  printf("-----seeking-----\n");
+  ReadOptions readOptions;
+  Status status;
+  int key_num = data_size / value_size;
+  srand(static_cast<unsigned int>(time(0)));
+  for (int i = 0; i < key_num; i++) {
+      //int key_ = rand() % key_num+1;
+      int key_ = i+1;
+      std::string key = std::to_string(key_);
+      std::string value;
+      status = db->Get(readOptions, key, &value);
+      if(isTimeout)   assert(status.IsNotFound());
+      else{
+        assert(status.ok());
+        std::cout << value << std::endl;
+      }
+  }
+}
+
+void TimeOut() {
+DB *db;
+  printf("-----opening-----\n");
+  if(OpenDB("testdb", &db).ok() == false) {
+      std::cerr << "open db failed" << std::endl;
+      abort();
+  }
+
+  uint64_t ttl = 3;
+
+  InsertData(db, ttl);
+  GetData(db, false);
+
+  Env::Default()->SleepForMicroseconds(ttl * 1000000);
+  GetData(db, true);
+
+  delete(db);
+  printf("-----closing-----\n");
+
+  // printf("-----recovery-----\n");
+  // if(OpenDB("testdb", &db).ok() == false) {
+  //     std::cerr << "open db failed" << std::endl;
+  //     abort();
+  // }
+  // GetData(db, true);
+  printf("success!\n");
+}
+
+void GetEarlierData() {
+DB *db;
+  printf("-----opening-----\n");
+  if(OpenDB("testdb", &db).ok() == false) {
+      std::cerr << "open db failed" << std::endl;
+      abort();
+  }
+
+  uint64_t ttl1 = 3;
+  uint64_t ttl2 = 5;
+
+  InsertData(db, ttl2);
+  InsertData(db, ttl1, 2);
+
+  //都没过期先找到后插的
+  Env::Default()->SleepForMicroseconds(1 * 1000000);
+  GetData(db, false);
+  
+  //再找到前一次
+  Env::Default()->SleepForMicroseconds(3 * 1000000);
+  GetData(db, false);
+
+  delete(db);
+  printf("-----closing-----\n");
+  printf("success!\n");
+}
+
+int main(int argc, char** argv) {
+  GetEarlierData();
+}

test/ttl_test.cc

@@ -78,33 +78,33 @@ TEST(TestTTL, ReadTTL) {
     }
 }
 
-TEST(TestTTL, CompactionTTL) {
-    DB *db;
+// TEST(TestTTL, CompactionTTL) {
+//     DB *db;
 
-    if(OpenDB("testdb", &db).ok() == false) {
-        std::cerr << "open db failed" << std::endl;
-        abort();
-    }
+//     if(OpenDB("testdb", &db).ok() == false) {
+//         std::cerr << "open db failed" << std::endl;
+//         abort();
+//     }
 
-    uint64_t ttl = 20;
-    InsertData(db, ttl);
+//     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);
+//     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);
+//     Env::Default()->SleepForMicroseconds(ttl * 1000000);
 
-    db->CompactRange(nullptr, nullptr);
+//     db->CompactRange(nullptr, nullptr);
 
-    leveldb::Range ranges[1];
-    ranges[0] = leveldb::Range("-", "A");
-    uint64_t sizes[1];
-    db->GetApproximateSizes(ranges, 1, sizes);
-    ASSERT_EQ(sizes[0], 0);
-}
+//     leveldb::Range ranges[1];
+//     ranges[0] = leveldb::Range("-", "A");
+//     uint64_t sizes[1];
+//     db->GetApproximateSizes(ranges, 1, sizes);
+//     ASSERT_EQ(sizes[0], 0);
+// }
 
 
 int main(int argc, char** argv) {