[reseek bugfix] add reseekdone flag

Author: Layamon

db/db_iter.cc

@@ -429,7 +429,7 @@ bool DBIter::FindNextUserEntryInternal(bool skipping, bool prefix_check) {
   //                         greater than that,
   //  - none of the above  : saved_key_ can contain anything, it doesn't matter.
   uint64_t num_skipped = 0;
-
+  bool reseek_done = false;
   do {
     if (!ParseKey(&ikey_)) {
       return false;
@@ -457,6 +457,7 @@ bool DBIter::FindNextUserEntryInternal(bool skipping, bool prefix_check) {
         PERF_COUNTER_ADD(internal_key_skipped_count, 1);
       } else {
         num_skipped = 0;
+        reseek_done = false;
         switch (ikey_.type) {
           case kTypeDeletion:
           case kTypeSingleDeletion:
@@ -500,6 +501,7 @@ bool DBIter::FindNextUserEntryInternal(bool skipping, bool prefix_check) {
                 // they are hidden by this deletion.
                 skipping = true;
                 num_skipped = 0;
+                reseek_done = false;
                 PERF_COUNTER_ADD(internal_delete_skipped_count, 1);
               } else {
                 value_ = GetValue(ikey_, kTypeValueIndex);
@@ -517,6 +519,7 @@ bool DBIter::FindNextUserEntryInternal(bool skipping, bool prefix_check) {
               // they are hidden by this deletion.
               skipping = true;
               num_skipped = 0;
+              reseek_done = false;
               PERF_COUNTER_ADD(internal_delete_skipped_count, 1);
             } else {
               // By now, we are sure the current ikey is going to yield a
@@ -545,13 +548,15 @@ bool DBIter::FindNextUserEntryInternal(bool skipping, bool prefix_check) {
         saved_key_.SetUserKey(ikey_.user_key);
         skipping = false;
         num_skipped = 0;
+        reseek_done = false;
       }
     }
 
     // If we have sequentially iterated via numerous equal keys, then it's
     // better to seek so that we can avoid too many key comparisons.
-    if (num_skipped > max_skip_ && CanReseekToSkip()) {
+    if (num_skipped > max_skip_ && !reseek_done) {
       num_skipped = 0;
+      reseek_done = true;
       std::string last_key;
       if (skipping) {
         // We're looking for the next user-key but all we see are the same

utilities/transactions/write_prepared_txn.cc

@@ -102,7 +102,6 @@ Status WritePreparedTxn::PrepareInternal() {
   assert(!s.ok() || seq_used != kMaxSequenceNumber);
   auto prepare_seq = seq_used;
   SetId(prepare_seq);
-  TEST_SYNC_POINT_CALLBACK("WritePreparedTxn::PrepareInternal::End", nullptr);
   return s;
 }