fix deletion bug for version 2

CMakeLists.txt

@@ -521,7 +521,7 @@ add_executable(db_test1
 "${PROJECT_SOURCE_DIR}/test/test.cpp"
       )
 target_link_libraries(db_test1 PRIVATE leveldb gtest)
-add_executable(db_test2
+add_executable(db_test_bench
 "${PROJECT_SOURCE_DIR}/test/benchmark_4leveldb.cpp"
       )
-target_link_libraries(db_test2 PRIVATE leveldb gtest)
+target_link_libraries(db_test_bench PRIVATE leveldb gtest)

db/db_impl.cc

@@ -1044,7 +1044,7 @@ Status DBImpl::DoCompactionWork(CompactionState* compact) {
       Slice old_value=input->value();
       Slice new_value;
       std::string buf="";
-      if(old_value.data()[0]==(char)(0x00)){
+      if(old_value.size()==0||old_value.data()[0]==(char)(0x00)){//when it is a deletion, input->value() will be ""
         new_value=old_value;
       }
       else{

include/leveldb/slice.h

@@ -69,6 +69,9 @@ class LEVELDB_EXPORT Slice {
 
   // Drop the first "n" bytes from this slice.
   void remove_prefix(size_t n) {
+    if(n>size()){
+      assert(0);
+    }
     assert(n <= size());
     data_ += n;
     size_ -= n;

test/benchmark_4leveldb.cpp

@@ -7,11 +7,11 @@
 #include "leveldb/db.h"
 
 // 配置
-const int TEST_EXPONENT = 4;
+const int TEST_EXPONENT = 5;
 const int TEST_FREQUENCY = static_cast<int>(std::pow(10, TEST_EXPONENT));
 const int MIN_STR_LEN = 255;
 const int MAX_STR_LEN = 1024;
-const std::string DB_PATH = "./db_benchmark";
+const std::string DB_PATH = "db_benchmark";
 const std::string CHARSET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
 
 // 多语言