From a79b65ecd0460c4e8f4e8973ec6a78bdba07772b Mon Sep 17 00:00:00 2001
From: Hui Xiao <huixiao@fb.com>
Date: Tue, 24 Sep 2024 18:15:11 -0700
Subject: [PATCH] draft

---
 file/prefetch_test.cc                         |  5 +++
 .../block_based/block_based_table_iterator.cc |  8 ++++
 .../block_based/block_based_table_iterator.h  | 37 ++++++++++++++++---
 3 files changed, 44 insertions(+), 6 deletions(-)

diff --git a/file/prefetch_test.cc b/file/prefetch_test.cc
index 20d85a785d8..01a8b94a65c 100644
--- a/file/prefetch_test.cc
+++ b/file/prefetch_test.cc
@@ -1249,6 +1249,7 @@ TEST_P(PrefetchTest, PrefetchWhenReseekwithCache) {
   Close();
 }
 
+// Best UT integration for correctness coverage
 TEST_P(PrefetchTest, PrefetchWithBlockLookupAutoTuneTest) {
   if (mem_env_ || encrypted_env_) {
     ROCKSDB_GTEST_SKIP("Test requires non-mem or non-encrypted environment");
@@ -1262,6 +1263,7 @@ TEST_P(PrefetchTest, PrefetchWithBlockLookupAutoTuneTest) {
   Options options;
   SetGenericOptions(env.get(), /*use_direct_io=*/false, options);
   options.statistics = CreateDBStatistics();
+  options.prefix_extractor.reset(NewFixedPrefixTransform(7));
   BlockBasedTableOptions table_options;
   SetBlockBasedTableOptions(table_options);
   options.table_factory.reset(NewBlockBasedTableFactory(table_options));
@@ -1333,8 +1335,10 @@ TEST_P(PrefetchTest, PrefetchWithBlockLookupAutoTuneTest) {
 
     ReadOptions ropts;
     ropts.auto_readahead_size = true;
+    ropts.prefix_same_as_start = true;
     ReadOptions cmp_ro;
     cmp_ro.auto_readahead_size = false;
+            cmp_ro.prefix_same_as_start = true;
 
     if (std::get<0>(GetParam())) {
       ropts.readahead_size = cmp_ro.readahead_size = 32768;
@@ -1354,6 +1358,7 @@ TEST_P(PrefetchTest, PrefetchWithBlockLookupAutoTuneTest) {
         cmp_ro.iterate_upper_bound = ub_ptr;
         ropts.iterate_upper_bound = ub_ptr;
 
+
         auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ropts));
         auto cmp_iter = std::unique_ptr<Iterator>(db_->NewIterator(cmp_ro));
 
diff --git a/table/block_based/block_based_table_iterator.cc b/table/block_based/block_based_table_iterator.cc
index 14db24d9b3c..f820fa0bca5 100644
--- a/table/block_based/block_based_table_iterator.cc
+++ b/table/block_based/block_based_table_iterator.cc
@@ -35,6 +35,14 @@ void BlockBasedTableIterator::SeekSecondPass(const Slice* target) {
 
 void BlockBasedTableIterator::SeekImpl(const Slice* target,
                                        bool async_prefetch) {
+  // Invalid transform
+  // Tranform user timestamp
+  // best place to set `prefix_for_same_as_start_`
+  if (prefix_extractor_) {
+    prefix_for_same_as_start_ =
+        prefix_extractor_->Transform(ExtractUserKey(*target));
+  }
+
   bool is_first_pass = !async_read_in_progress_;
 
   if (!is_first_pass) {
diff --git a/table/block_based/block_based_table_iterator.h b/table/block_based/block_based_table_iterator.h
index 2b562ef0679..f107f296cb8 100644
--- a/table/block_based/block_based_table_iterator.h
+++ b/table/block_based/block_based_table_iterator.h
@@ -353,6 +353,10 @@ class BlockBasedTableIterator : public InternalIteratorBase<Slice> {
   // is used to disable the lookup.
   IterDirection direction_ = IterDirection::kForward;
 
+  // perf for stroing slice
+  // naming
+  Slice prefix_for_same_as_start_ = nullptr;
+
   void SeekSecondPass(const Slice* target);
 
   // If `target` is null, seek to first.
@@ -411,12 +415,33 @@ class BlockBasedTableIterator : public InternalIteratorBase<Slice> {
   bool IsNextBlockOutOfBound() {
     // If curr block's index key >= iterate_upper_bound, it means all the keys
     // in next block or above are out of bound.
-    return (user_comparator_.CompareWithoutTimestamp(
-                index_iter_->user_key(),
-                /*a_has_ts=*/true, *read_options_.iterate_upper_bound,
-                /*b_has_ts=*/false) >= 0
-                ? true
-                : false);
+    // return (user_comparator_.CompareWithoutTimestamp(
+    //         index_iter_->user_key(),
+    //         /*a_has_ts=*/true, *read_options_.iterate_upper_bound,
+    //         /*b_has_ts=*/false) >= 0
+    //         ? true
+    //         : false);
+    bool out_of_upper_bound =
+        (user_comparator_.CompareWithoutTimestamp(
+             index_iter_->user_key(),
+             /*a_has_ts=*/true, *read_options_.iterate_upper_bound,
+             /*b_has_ts=*/false) >= 0
+             ? true
+             : false);
+    if (out_of_upper_bound) {
+      return true;
+    }
+
+    bool out_of_prefix_bound =
+        (read_options_.prefix_same_as_start &&
+         prefix_for_same_as_start_ != nullptr &&
+         prefix_extractor_->Transform(index_iter_->user_key())
+                 .compare(prefix_for_same_as_start_) != 0);
+    if (out_of_prefix_bound) {
+      return true;
+    }
+
+    return false;
   }
 
   void ClearBlockHandles() {