db_bench cleanup

Summary:
clean up the db_bench a little bit. also avoid allocating memory for key
in the loop

Test Plan:
I verified a run with filluniquerandom & readrandom. Iterator seek will be used lot
to measure performance. Will fix whatever comes up

Reviewers: haobo, igor, yhchiang

Reviewed By: igor

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17559

port/port_example.h

@@ -127,13 +127,6 @@ extern bool Snappy_GetUncompressedLength(const char* input, size_t length,
 extern bool Snappy_Uncompress(const char* input_data, size_t input_length,
                               char* output);
 
-// ------------------ Miscellaneous -------------------
-
-// If heap profiling is not supported, returns false.
-// Else repeatedly calls (*func)(arg, data, n) and then returns true.
-// The concatenation of all "data[0,n-1]" fragments is the heap profile.
-extern bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg);
-
 }  // namespace port
 }  // namespace rocksdb
 

port/port_posix.h

@@ -476,10 +476,6 @@ inline bool LZ4HC_Compress(const CompressionOptions &opts, const char* input,
   return false;
 }
 
-inline bool GetHeapProfile(void (*func)(void *, const char *, int), void *arg) {
-  return false;
-}
-
 #define CACHE_LINE_SIZE 64U
 
 } // namespace port