fix simple typos (#1183)

db/db_impl.h

@@ -358,7 +358,7 @@ class DBImpl : public DB {
 
 #endif  // NDEBUG
 
-  // Return maximum background compaction alowed to be scheduled based on
+  // Return maximum background compaction allowed to be scheduled based on
   // compaction status.
   int BGCompactionsAllowed() const;
 

db/db_wal_test.cc

@@ -953,7 +953,7 @@ TEST_F(DBWALTest, RecoverFromCorruptedWALWithoutFlush) {
             std::string value = DummyString(RecoveryTestHelper::kValueSize);
             ASSERT_OK(Put(key, value));
           }
-          // Save data for comparision.
+          // Save data for comparison.
           auto data = getAll();
           // Reopen. Verify data.
           ASSERT_OK(TryReopen(options));

db/write_batch.cc

@@ -1012,7 +1012,7 @@ class MemTableInserter : public WriteBatch::Handler {
         // at this point individual CF lognumbers will prevent
         // duplicate re-insertion of values.
         assert(log_number_ref_ == 0);
-        // all insertes must refernce this trx log number
+        // all insertes must reference this trx log number
         log_number_ref_ = trx->log_number_;
         s = trx->batch_->Iterate(this);
         log_number_ref_ = 0;

db/write_thread.h

@@ -193,7 +193,7 @@ class WriteThread {
   // writer.  If w has become the leader of a write batch group, returns
   // STATE_GROUP_LEADER.  If w has been made part of a sequential batch
   // group and the leader has performed the write, returns STATE_DONE.
-  // If w has been made part of a parallel batch group and is reponsible
+  // If w has been made part of a parallel batch group and is responsible
   // for updating the memtable, returns STATE_PARALLEL_FOLLOWER.
   //
   // The db mutex SHOULD NOT be held when calling this function, because

include/rocksdb/statistics.h

@@ -359,7 +359,7 @@ enum StatsLevel {
   kExceptTimeForMutex,
   // Collect all stats, including measuring duration of mutex operations.
   // If getting time is expensive on the platform to run, it can
-  // reduce scalability to more threads, especialy for writes.
+  // reduce scalability to more threads, especially for writes.
   kAll,
 };
 

third-party/fbson/FbsonJsonParser.h

@@ -40,7 +40,7 @@
  * string to an id, and store the dictionary id in FBSON to save space. The
  * purpose of using an external dictionary is more towards a collection of
  * documents (which has common keys) rather than a single document, so that
- * space saving will be siginificant.
+ * space saving will be significant.
  *
  * ** Endianness **
  * Note: FBSON serialization doesn't assume endianness of the server. However

utilities/persistent_cache/hash_table.h

@@ -22,7 +22,7 @@ namespace rocksdb {
 
 // HashTable<T, Hash, Equal>
 //
-// Traditional implementation of hash table with syncronization built on top
+// Traditional implementation of hash table with synchronization built on top
 // don't perform very well in multi-core scenarios. This is an implementation
 // designed for multi-core scenarios with high lock contention.
 //

utilities/persistent_cache/lrulist.h

@@ -164,7 +164,7 @@ class LRUList {
     }
   }
 
-  mutable port::Mutex lock_;  // syncronization primitive
+  mutable port::Mutex lock_;  // synchronization primitive
   T* head_ = nullptr;         // front (cold)
   T* tail_ = nullptr;         // back (hot)
 };