Fix some typos in code comments (facebook#6733)

Summary:
This PR fixes some typos in code comments.
Pull Request resolved: facebook#6733

Reviewed By: siying

Differential Revision: D21209037

Pulled By: zhichao-cao

fbshipit-source-id: d9274611fab1f5e992998c8c4117b8078c4cbc69

table/block_based/block.cc

@@ -293,15 +293,15 @@ bool DataBlockIter::SeekForGetImpl(const Slice& target) {
 
   if (entry == kNoEntry) {
     // Even if we cannot find the user_key in this block, the result may
-    // exist in the next block. Consider this exmpale:
+    // exist in the next block. Consider this example:
     //
     // Block N:    [aab@100, ... , app@120]
     // bounary key: axy@50 (we make minimal assumption about a boundary key)
     // Block N+1:  [axy@10, ...   ]
     //
     // If seek_key = axy@60, the search will starts from Block N.
     // Even if the user_key is not found in the hash map, the caller still
-    // have to conntinue searching the next block.
+    // have to continue searching the next block.
     //
     // In this case, we pretend the key is the the last restart interval.
     // The while-loop below will search the last restart interval for the
@@ -627,7 +627,7 @@ bool IndexBlockIter::ParseNextIndexKey() {
 // restart_point n-1: k, v (off, sz), k, v (delta-sz), ..., k, v (delta-sz)
 // where, k is key, v is value, and its encoding is in parenthesis.
 // The format of each key is (shared_size, non_shared_size, shared, non_shared)
-// The format of each value, i.e., block hanlde, is (offset, size) whenever the
+// The format of each value, i.e., block handle, is (offset, size) whenever the
 // shared_size is 0, which included the first entry in each restart point.
 // Otherwise the format is delta-size = block handle size - size of last block
 // handle.

table/block_based/block_based_table_reader.cc

@@ -2171,7 +2171,7 @@ Status BlockBasedTable::Get(const ReadOptions& read_options, const Slice& key,
 
     size_t ts_sz =
         rep_->internal_comparator.user_comparator()->timestamp_size();
-    bool matched = false;  // if such user key mathced a key in SST
+    bool matched = false;  // if such user key matched a key in SST
     bool done = false;
     for (iiter->Seek(key); iiter->Valid() && !done; iiter->Next()) {
       IndexValue v = iiter->value();

table/block_based/block_based_table_reader.h

@@ -454,7 +454,7 @@ class BlockBasedTable : public TableReader {
   friend class DBBasicTest_MultiGetIOBufferOverrun_Test;
 };
 
-// Maitaning state of a two-level iteration on a partitioned index structure.
+// Maintaining state of a two-level iteration on a partitioned index structure.
 class BlockBasedTable::PartitionedIndexIteratorState
     : public TwoLevelIteratorState {
  public:

test_util/sync_point.h

@@ -127,7 +127,7 @@ class SyncPoint {
 }  // namespace ROCKSDB_NAMESPACE
 
 // Use TEST_SYNC_POINT to specify sync points inside code base.
-// Sync points can have happens-after depedency on other sync points,
+// Sync points can have happens-after dependency on other sync points,
 // configured at runtime via SyncPoint::LoadDependency. This could be
 // utilized to re-produce race conditions between threads.
 // See TransactionLogIteratorRace in db_test.cc for an example use case.