fixed typo

Summary:
fixed exisitng -> existing
Closes https://github.com/facebook/rocksdb/pull/2305

Differential Revision: D5070169

Pulled By: yiwu-arbug

fbshipit-source-id: 8c8450acf50757b767cf78b78314018395738d96

db/write_thread.cc

@@ -229,7 +229,7 @@ void WriteThread::JoinBatchGroup(Writer* w) {
     /**
      * Wait util:
      * 1) An existing leader pick us as the new leader when it finishes
-     * 2) An exisitng leader pick us as its follewer and
+     * 2) An existing leader pick us as its follewer and
      * 2.1) finishes the memtable writes on our behalf
      * 2.2) Or tell us to finish the memtable writes it in pralallel
      */

third-party/gtest-1.7.0/fused-src/gtest/gtest-all.cc

@@ -8229,7 +8229,7 @@ FilePath FilePath::RemoveExtension(const char* extension) const {
   return *this;
 }
 
-// Returns a pointer to the last occurence of a valid path separator in
+// Returns a pointer to the last occurrence of a valid path separator in
 // the FilePath. On Windows, for example, both '/' and '\' are valid path
 // separators. Returns NULL if no path separator was found.
 const char* FilePath::FindLastPathSeparator() const {

tools/write_stress.cc

@@ -81,7 +81,7 @@ DEFINE_int32(key_size, 10, "Key size");
 DEFINE_int32(value_size, 100, "Value size");
 DEFINE_string(db, "", "Use the db with the following name.");
 DEFINE_bool(destroy_db, true,
-            "Destory the existing DB before running the test");
+            "Destroy the existing DB before running the test");
 
 DEFINE_int32(runtime_sec, 10 * 60, "How long are we running for, in seconds");
 DEFINE_int32(seed, 139, "Random seed");