修改了lookupkey和比较器逻辑，能在最新的key过期后查之前有无存在的key

db/db_impl.cc

@@ -1143,7 +1143,11 @@ 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

db/dbformat.cc

@@ -12,12 +12,14 @@
 
 namespace leveldb {
 
-static uint64_t PackSequenceAndTypeAndTtl(uint64_t seq, ValueType t, bool havettl) {
+static uint64_t PackSequenceAndTypeAndTtlAndLookup(
+                      uint64_t seq, ValueType t, bool havettl, bool islookup) {
   assert(seq <= kMaxSequenceNumber);
   assert(t <= kValueTypeForSeek);
-  return (seq << 8) | (havettl << 1) | t;
+  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);
@@ -28,8 +30,8 @@ void AppendInternalKey(std::string* result, const ParsedInternalKey& key) {
   result->append(key.user_key.data(), key.user_key.size());
   if(key.deadTime != 0)
     PutFixed64(result, key.deadTime);
-  PutFixed64(result, PackSequenceAndTypeAndTtl(
-                                key.sequence, key.type, (key.deadTime != 0)));
+  PutFixed64(result, PackSequenceAndTypeAndTtlAndLookup(
+                                key.sequence, key.type, (key.deadTime != 0), false));
 }
 
 std::string ParsedInternalKey::DebugString() const {
@@ -58,13 +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) | 0b10;
-    const uint64_t bnum = DecodeFixed64(bkey.data() + bkey.size() - 8) | 0b10;
-    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;
-    } else if (anum < bnum) {
+      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;
+        return r;
+      }
+    }
+    
+    if (aseq < bseq) {
       r = +1;
     }
   }
@@ -123,9 +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_;
@@ -133,11 +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

@@ -98,9 +98,10 @@ bool ParseInternalKey(const Slice& internal_key, ParsedInternalKey* result);
 inline Slice ExtractUserKey(const Slice& internal_key) {
   assert(internal_key.size() >= 8);
   uint64_t num = DecodeFixed64(internal_key.data() + internal_key.size() - 8);
-  uint8_t havettl = (num & 0xff) >> 1;
+  uint8_t havettl = (num & 0b10) >> 1;
+  uint8_t islookup = (num & 0b100) >> 2;
   size_t klen = internal_key.size() - 8;
-  if(havettl)  klen -= 8;
+  if(havettl || islookup)  klen -= 8;
   Slice user_key = Slice(internal_key.data(), klen);
   return user_key;
 }
@@ -179,14 +180,14 @@ 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 tag = DecodeFixed64(internal_key.data() + n - 8);
   uint8_t c = tag & 0xff;
-  uint8_t havettl = c >> 1;
-  assert(havettl <= 0b1);
+  uint8_t havettl = (c & 0b10) >> 1;
   result->sequence = tag >> 8;
-  result->type = static_cast<ValueType>(c);
+  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);
@@ -202,7 +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;
@@ -216,14 +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/memtable.cc

@@ -145,18 +145,18 @@ bool MemTable::Get(const LookupKey& key, std::string* value, Status* s) {
       const uint64_t tag = DecodeFixed64(key_ptr + key_length - 8);
       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
-              }
-          }
+          // 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;

test/ttl_mmtable_test.cc

@@ -3,12 +3,12 @@
 #include "ctime"
 #include <iostream>
 #include <cstdlib>
-
+#include "gtest/gtest.h"
 
 using namespace leveldb;
 
 constexpr int value_size = 2048;
-constexpr int data_size = 4096 << 1;
+constexpr int data_size = 2048 << 2;
 
 Status OpenDB(std::string dbName, DB **db) {
   Options options;
@@ -16,7 +16,7 @@ Status OpenDB(std::string dbName, DB **db) {
   return DB::Open(options, dbName, db);
 }
 
-void InsertData(DB *db, uint64_t ttl/* second */) {
+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;
@@ -27,59 +27,87 @@ void InsertData(DB *db, uint64_t ttl/* second */) {
     //int key_ = rand() % key_num+1;
     int key_ = i+1;
     std::string key = std::to_string(key_);
-    std::string value(value_size, 'a');
+    std::string value(vsize, 'a');
     status = db->Put(writeOptions, key, value, ttl);
     assert(status.ok());
   }
 }
 
-void GetData(DB *db, int size = (1 << 30)) {
+void GetData(DB *db, bool isTimeout) {
+  printf("-----seeking-----\n");
   ReadOptions readOptions;
+  Status status;
   int key_num = data_size / value_size;
-  
-  // 点查
   srand(static_cast<unsigned int>(time(0)));
-  for (int i = 0; i < 100; i++) {
-    int key_ = rand() % key_num+1;
-    std::string key = std::to_string(key_);
-    std::string value;
-    db->Get(readOptions, key, &value);
+  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;
+      }
   }
 }
 
-int main(int argc, char** argv) {
+void TimeOut() {
 DB *db;
-    if(OpenDB("testdb", &db).ok() == false) {
-        std::cerr << "open db failed" << std::endl;
-        abort();
-    }
-
-    uint64_t ttl = 3;
-
-    InsertData(db, ttl);
-
-    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);
-        assert(status.ok());
-    }
-
-    Env::Default()->SleepForMicroseconds(ttl * 1000000);
-
-    for (int i = 0; i < key_num; i++) {
-        int key_ = rand() % key_num+1;
-        std::string key = std::to_string(key_);
-        std::string value;
-        status = db->Get(readOptions, key, &value);
-        assert(status.IsNotFound());
-    }
-    printf("success!\n");
+  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();
 }