merge: Merge remote-tracking branch google/main@4fb1468

Signed-off-by: KunoiSayami <[email protected]>

52 files changed, 278 insertions, 337 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f807626..0890b9f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -148,7 +148,7 @@ target_sources(leveldb
     "db/memtable.h"
     "db/repair.cc"
     "db/skiplist.h"
-        "db/skiplist.cuh"
+    "db/skiplist.cuh"
     "db/skiplist.cu"
     "db/snapshot.h"
     "db/table_cache.cc"
@@ -315,11 +315,6 @@ if(LEVELDB_BUILD_TESTS)
   # This project is tested using GoogleTest.
   add_subdirectory("third_party/googletest")
 
-  # This project uses Google benchmark for benchmarking.
-  set(BENCHMARK_ENABLE_TESTING OFF CACHE BOOL "" FORCE)
-  set(BENCHMARK_ENABLE_EXCEPTIONS OFF CACHE BOOL "" FORCE)
-  add_subdirectory("third_party/benchmark")
-
   # GoogleTest triggers a missing field initializers warning.
   if(LEVELDB_HAVE_NO_MISSING_FIELD_INITIALIZERS)
     set_property(TARGET gtest
@@ -328,6 +323,60 @@ if(LEVELDB_BUILD_TESTS)
         APPEND PROPERTY COMPILE_OPTIONS -Wno-missing-field-initializers)
   endif(LEVELDB_HAVE_NO_MISSING_FIELD_INITIALIZERS)
 
+  add_executable(leveldb_tests "")
+  target_sources(leveldb_tests
+    PRIVATE
+      # "db/fault_injection_test.cc"
+      # "issues/issue178_test.cc"
+      # "issues/issue200_test.cc"
+      # "issues/issue320_test.cc"
+      "${PROJECT_BINARY_DIR}/${LEVELDB_PORT_CONFIG_DIR}/port_config.h"
+      # "util/env_test.cc"
+      "util/status_test.cc"
+      "util/no_destructor_test.cc"
+      "util/testutil.cc"
+      "util/testutil.h"
+  )
+  if(NOT BUILD_SHARED_LIBS)
+    target_sources(leveldb_tests
+      PRIVATE
+        "db/autocompact_test.cc"
+        "db/corruption_test.cc"
+        "db/db_test.cc"
+        "db/dbformat_test.cc"
+        "db/filename_test.cc"
+        "db/log_test.cc"
+        "db/recovery_test.cc"
+        "db/skiplist_test.cc"
+        "db/version_edit_test.cc"
+        "db/version_set_test.cc"
+        "db/write_batch_test.cc"
+        "helpers/memenv/memenv_test.cc"
+        "table/filter_block_test.cc"
+        "table/table_test.cc"
+        "util/arena_test.cc"
+        "util/bloom_test.cc"
+        "util/cache_test.cc"
+        "util/coding_test.cc"
+        "util/crc32c_test.cc"
+        "util/hash_test.cc"
+        "util/logging_test.cc"
+    )
+  endif(NOT BUILD_SHARED_LIBS)
+  target_link_libraries(leveldb_tests leveldb gmock gtest gtest_main)
+  target_compile_definitions(leveldb_tests
+    PRIVATE
+      ${LEVELDB_PLATFORM_NAME}=1
+  )
+  if (NOT HAVE_CXX17_HAS_INCLUDE)
+    target_compile_definitions(leveldb_tests
+      PRIVATE
+        LEVELDB_HAS_PORT_CONFIG_H=1
+    )
+  endif(NOT HAVE_CXX17_HAS_INCLUDE)
+
+  add_test(NAME "leveldb_tests" COMMAND "leveldb_tests")
+
   function(leveldb_test test_file)
     get_filename_component(test_target_name "${test_file}" NAME_WE)
 
@@ -340,7 +389,7 @@ if(LEVELDB_BUILD_TESTS)
 
         "${test_file}"
     )
-    target_link_libraries("${test_target_name}" leveldb gmock gtest benchmark)
+    target_link_libraries("${test_target_name}" leveldb gmock gtest)
     target_compile_definitions("${test_target_name}"
       PRIVATE
         ${LEVELDB_PLATFORM_NAME}=1
@@ -358,42 +407,8 @@ if(LEVELDB_BUILD_TESTS)
   endfunction(leveldb_test)
 
   leveldb_test("db/c_test.c")
-  leveldb_test("db/fault_injection_test.cc")
-
-  leveldb_test("issues/issue178_test.cc")
-  leveldb_test("issues/issue200_test.cc")
-  leveldb_test("issues/issue320_test.cc")
-
-  leveldb_test("util/env_test.cc")
-  leveldb_test("util/status_test.cc")
-  leveldb_test("util/no_destructor_test.cc")
 
   if(NOT BUILD_SHARED_LIBS)
-    leveldb_test("db/autocompact_test.cc")
-    leveldb_test("db/corruption_test.cc")
-    leveldb_test("db/db_test.cc")
-    leveldb_test("db/dbformat_test.cc")
-    leveldb_test("db/filename_test.cc")
-    leveldb_test("db/log_test.cc")
-    leveldb_test("db/recovery_test.cc")
-    leveldb_test("db/skiplist_test.cu")
-    leveldb_test("db/version_edit_test.cc")
-    leveldb_test("db/version_set_test.cc")
-    leveldb_test("db/write_batch_test.cc")
-
-    leveldb_test("helpers/memenv/memenv_test.cc")
-
-    leveldb_test("table/filter_block_test.cc")
-    leveldb_test("table/table_test.cc")
-
-    leveldb_test("util/arena_test.cc")
-    leveldb_test("util/bloom_test.cc")
-    leveldb_test("util/cache_test.cc")
-    leveldb_test("util/coding_test.cc")
-    leveldb_test("util/crc32c_test.cc")
-    leveldb_test("util/hash_test.cc")
-    leveldb_test("util/logging_test.cc")
-
     # TODO(costan): This test also uses
     #               "util/env_{posix|windows}_test_helper.h"
     if (WIN32)
@@ -405,6 +420,11 @@ if(LEVELDB_BUILD_TESTS)
 endif(LEVELDB_BUILD_TESTS)
 
 if(LEVELDB_BUILD_BENCHMARKS)
+  # This project uses Google benchmark for benchmarking.
+  set(BENCHMARK_ENABLE_TESTING OFF CACHE BOOL "" FORCE)
+  set(BENCHMARK_ENABLE_EXCEPTIONS OFF CACHE BOOL "" FORCE)
+  add_subdirectory("third_party/benchmark")
+
   function(leveldb_benchmark bench_file)
     get_filename_component(bench_target_name "${bench_file}" NAME_WE)
 
@@ -419,7 +439,7 @@ if(LEVELDB_BUILD_BENCHMARKS)
 
         "${bench_file}"
     )
-    target_link_libraries("${bench_target_name}" leveldb gmock gtest)
+    target_link_libraries("${bench_target_name}" leveldb gmock gtest benchmark)
     target_compile_definitions("${bench_target_name}"
       PRIVATE
         ${LEVELDB_PLATFORM_NAME}=1
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 7ede021..9d8a7d7 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -1,36 +1,31 @@
-# Contributing
+# How to Contribute
 
-We'd love to accept your code patches! However, before we can take them, we
-have to jump a couple of legal hurdles.
+We'd love to accept your patches and contributions to this project. There are
+just a few small guidelines you need to follow.
 
-## Contributor License Agreements
+## Contributor License Agreement
 
-Please fill out either the individual or corporate Contributor License
-Agreement as appropriate.
+Contributions to this project must be accompanied by a Contributor License
+Agreement. You (or your employer) retain the copyright to your contribution;
+this simply gives us permission to use and redistribute your contributions as
+part of the project. Head over to <https://cla.developers.google.com/> to see
+your current agreements on file or to sign a new one.
 
-* If you are an individual writing original source code and you're sure you
-own the intellectual property, then sign an [individual CLA](https://developers.google.com/open-source/cla/individual).
-* If you work for a company that wants to allow you to contribute your work,
-then sign a [corporate CLA](https://developers.google.com/open-source/cla/corporate).
+You generally only need to submit a CLA once, so if you've already submitted one
+(even if it was for a different project), you probably don't need to do it
+again.
 
-Follow either of the two links above to access the appropriate CLA and
-instructions for how to sign and return it.
+## Code Reviews
 
-## Submitting a Patch
+All submissions, including submissions by project members, require review. We
+use GitHub pull requests for this purpose. Consult
+[GitHub Help](https://help.github.com/articles/about-pull-requests/) for more
+information on using pull requests.
 
-1. Sign the contributors license agreement above.
-2. Decide which code you want to submit. A submission should be a set of changes
-that addresses one issue in the [issue tracker](https://github.com/google/leveldb/issues).
-Please don't mix more than one logical change per submission, because it makes
-the history hard to follow. If you want to make a change
-(e.g. add a sample or feature) that doesn't have a corresponding issue in the
-issue tracker, please create one.
-3. **Submitting**: When you are ready to submit, send us a Pull Request. Be
-sure to include the issue number you fixed and the name you used to sign
-the CLA.
+See [the README](README.md#contributing-to-the-leveldb-project) for areas
+where we are likely to accept external contributions.
 
-## Writing Code ##
+## Community Guidelines
 
-If your contribution contains code, please make sure that it follows
-[the style guide](https://google.github.io/styleguide/cppguide.html).
-Otherwise we will have to ask you to make changes, and that's no fun for anyone.
+This project follows [Google's Open Source Community
+Guidelines](https://opensource.google/conduct/).
diff --git a/README.md b/README.md
index 3c4d14d..3a24477 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,7 @@ Authors: Sanjay Ghemawat ([email protected]) and Jeff Dean ([email protected])
 
 # Documentation
 
-  [LevelDB library documentation](https://github.com/google/leveldb/blob/master/doc/index.md) is online and bundled with the source code.
+  [LevelDB library documentation](https://github.com/google/leveldb/blob/main/doc/index.md) is online and bundled with the source code.
 
 # Limitations
 
@@ -99,6 +99,12 @@ Contribution requirements:
    clang-format -i --style=file <file>
    ```
 
+We are unlikely to accept contributions to the build configuration files, such
+as `CMakeLists.txt`. We are focused on maintaining a build configuration that
+allows us to test that the project works in a few supported configurations
+inside Google. We are not currently interested in supporting other requirements,
+such as different operating systems, compilers, or build systems.
+
 ## Submitting a Pull Request
 
 Before any pull request will be accepted the author must first sign a
@@ -107,7 +113,7 @@ Contributor License Agreement (CLA) at https://cla.developers.google.com/.
 In order to keep the commit timeline linear
 [squash](https://git-scm.com/book/en/v2/Git-Tools-Rewriting-History#Squashing-Commits)
 your changes down to a single commit and [rebase](https://git-scm.com/docs/git-rebase)
-on google/leveldb/master. This keeps the commit timeline linear and more easily sync'ed
+on google/leveldb/main. This keeps the commit timeline linear and more easily sync'ed
 with the internal repository at Google. More information at GitHub's
 [About Git rebase](https://help.github.com/articles/about-git-rebase/) page.
 
diff --git a/benchmarks/db_bench_log.cc b/benchmarks/db_bench_log.cc
new file mode 100644
index 0000000..a1845bf
--- /dev/null
+++ b/benchmarks/db_bench_log.cc
@@ -0,0 +1,92 @@
+// Copyright (c) 2019 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include <cinttypes>
+#include <cstdio>
+#include <string>
+
+#include "gtest/gtest.h"
+#include "benchmark/benchmark.h"
+#include "db/version_set.h"
+#include "leveldb/comparator.h"
+#include "leveldb/db.h"
+#include "leveldb/env.h"
+#include "leveldb/options.h"
+#include "port/port.h"
+#include "util/mutexlock.h"
+#include "util/testutil.h"
+
+namespace leveldb {
+
+namespace {
+
+std::string MakeKey(unsigned int num) {
+  char buf[30];
+  std::snprintf(buf, sizeof(buf), "%016u", num);
+  return std::string(buf);
+}
+
+void BM_LogAndApply(benchmark::State& state) {
+  const int num_base_files = state.range(0);
+
+  std::string dbname = testing::TempDir() + "leveldb_test_benchmark";
+  DestroyDB(dbname, Options());
+
+  DB* db = nullptr;
+  Options opts;
+  opts.create_if_missing = true;
+  Status s = DB::Open(opts, dbname, &db);
+  ASSERT_LEVELDB_OK(s);
+  ASSERT_TRUE(db != nullptr);
+
+  delete db;
+  db = nullptr;
+
+  Env* env = Env::Default();
+
+  port::Mutex mu;
+  MutexLock l(&mu);
+
+  InternalKeyComparator cmp(BytewiseComparator());
+  Options options;
+  VersionSet vset(dbname, &options, nullptr, &cmp);
+  bool save_manifest;
+  ASSERT_LEVELDB_OK(vset.Recover(&save_manifest));
+  VersionEdit vbase;
+  uint64_t fnum = 1;
+  for (int i = 0; i < num_base_files; i++) {
+    InternalKey start(MakeKey(2 * fnum), 1, kTypeValue);
+    InternalKey limit(MakeKey(2 * fnum + 1), 1, kTypeDeletion);
+    vbase.AddFile(2, fnum++, 1 /* file size */, start, limit);
+  }
+  ASSERT_LEVELDB_OK(vset.LogAndApply(&vbase, &mu));
+
+  uint64_t start_micros = env->NowMicros();
+
+  for (auto st : state) {
+    VersionEdit vedit;
+    vedit.RemoveFile(2, fnum);
+    InternalKey start(MakeKey(2 * fnum), 1, kTypeValue);
+    InternalKey limit(MakeKey(2 * fnum + 1), 1, kTypeDeletion);
+    vedit.AddFile(2, fnum++, 1 /* file size */, start, limit);
+    vset.LogAndApply(&vedit, &mu);
+  }
+
+  uint64_t stop_micros = env->NowMicros();
+  unsigned int us = stop_micros - start_micros;
+  char buf[16];
+  std::snprintf(buf, sizeof(buf), "%d", num_base_files);
+  std::fprintf(stderr,
+               "BM_LogAndApply/%-6s   %8" PRIu64
+               " iters : %9u us (%7.0f us / iter)\n",
+               buf, state.iterations(), us, ((float)us) / state.iterations());
+}
+
+BENCHMARK(BM_LogAndApply)->Arg(1)->Arg(100)->Arg(10000)->Arg(100000);
+
+}  // namespace
+
+}  // namespace leveldb
+
+BENCHMARK_MAIN();
diff --git a/db/autocompact_test.cc b/db/autocompact_test.cc
index 3b7241b..69341e3 100644
--- a/db/autocompact_test.cc
+++ b/db/autocompact_test.cc
@@ -108,8 +108,3 @@ TEST_F(AutoCompactTest, ReadAll) { DoReads(kCount); }
 TEST_F(AutoCompactTest, ReadHalf) { DoReads(kCount / 2); }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/db/corruption_test.cc b/db/corruption_test.cc
index a31f448..dc7da76 100644
--- a/db/corruption_test.cc
+++ b/db/corruption_test.cc
@@ -360,8 +360,3 @@ TEST_F(CorruptionTest, UnrelatedKeys) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/db/db_test.cc b/db/db_test.cc
index 908b41d..9bd6e14 100644
--- a/db/db_test.cc
+++ b/db/db_test.cc
@@ -9,7 +9,6 @@
 #include <string>
 
 #include "gtest/gtest.h"
-#include "benchmark/benchmark.h"
 #include "db/db_impl.h"
 #include "db/filename.h"
 #include "db/version_set.h"
@@ -2295,72 +2294,4 @@ TEST_F(DBTest, Randomized) {
   } while (ChangeOptions());
 }
 
-std::string MakeKey(unsigned int num) {
-  char buf[30];
-  std::snprintf(buf, sizeof(buf), "%016u", num);
-  return std::string(buf);
-}
-
-static void BM_LogAndApply(benchmark::State& state) {
-  const int num_base_files = state.range(0);
-
-  std::string dbname = testing::TempDir() + "leveldb_test_benchmark";
-  DestroyDB(dbname, Options());
-
-  DB* db = nullptr;
-  Options opts;
-  opts.create_if_missing = true;
-  Status s = DB::Open(opts, dbname, &db);
-  ASSERT_LEVELDB_OK(s);
-  ASSERT_TRUE(db != nullptr);
-
-  delete db;
-  db = nullptr;
-
-  Env* env = Env::Default();
-
-  port::Mutex mu;
-  MutexLock l(&mu);
-
-  InternalKeyComparator cmp(BytewiseComparator());
-  Options options;
-  VersionSet vset(dbname, &options, nullptr, &cmp);
-  bool save_manifest;
-  ASSERT_LEVELDB_OK(vset.Recover(&save_manifest));
-  VersionEdit vbase;
-  uint64_t fnum = 1;
-  for (int i = 0; i < num_base_files; i++) {
-    InternalKey start(MakeKey(2 * fnum), 1, kTypeValue);
-    InternalKey limit(MakeKey(2 * fnum + 1), 1, kTypeDeletion);
-    vbase.AddFile(2, fnum++, 1 /* file size */, start, limit);
-  }
-  ASSERT_LEVELDB_OK(vset.LogAndApply(&vbase, &mu));
-
-  uint64_t start_micros = env->NowMicros();
-
-  for (auto st : state) {
-    VersionEdit vedit;
-    vedit.RemoveFile(2, fnum);
-    InternalKey start(MakeKey(2 * fnum), 1, kTypeValue);
-    InternalKey limit(MakeKey(2 * fnum + 1), 1, kTypeDeletion);
-    vedit.AddFile(2, fnum++, 1 /* file size */, start, limit);
-    vset.LogAndApply(&vedit, &mu);
-  }
-  uint64_t stop_micros = env->NowMicros();
-  unsigned int us = stop_micros - start_micros;
-  char buf[16];
-  std::snprintf(buf, sizeof(buf), "%d", num_base_files);
-  std::fprintf(stderr,
-               "BM_LogAndApply/%-6s   %8" PRIu64
-               " iters : %9u us (%7.0f us / iter)\n",
-               buf, state.iterations(), us, ((float)us) / state.iterations());
-}
-
-BENCHMARK(BM_LogAndApply)->Arg(1)->Arg(100)->Arg(10000)->Arg(100000);
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  benchmark::RunSpecifiedBenchmarks();
-  return RUN_ALL_TESTS();
-}
diff --git a/db/dbformat_test.cc b/db/dbformat_test.cc
index 4a11c4a..7f3f81a 100644
--- a/db/dbformat_test.cc
+++ b/db/dbformat_test.cc
@@ -126,8 +126,3 @@ TEST(FormatTest, InternalKeyDebugString) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/db/fault_injection_test.cc b/db/fault_injection_test.cc
index 6eebafa..ef864a4 100644
--- a/db/fault_injection_test.cc
+++ b/db/fault_injection_test.cc
@@ -548,8 +548,3 @@ TEST_F(FaultInjectionTest, FaultTestWithLogReuse) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/db/filename_test.cc b/db/filename_test.cc
index f291d72..9ac0111 100644
--- a/db/filename_test.cc
+++ b/db/filename_test.cc
@@ -125,8 +125,3 @@ TEST(FileNameTest, Construction) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/db/log_reader.h b/db/log_reader.h
index 75d53f7..ba711f8 100644
--- a/db/log_reader.h
+++ b/db/log_reader.h
@@ -24,7 +24,7 @@ class Reader {
    public:
     virtual ~Reporter();
 
-    // Some corruption was detected.  "size" is the approximate number
+    // Some corruption was detected.  "bytes" is the approximate number
     // of bytes dropped due to the corruption.
     virtual void Corruption(size_t bytes, const Status& status) = 0;
   };
diff --git a/db/log_test.cc b/db/log_test.cc
index 346b19c..d55d4dd 100644
--- a/db/log_test.cc
+++ b/db/log_test.cc
@@ -556,8 +556,3 @@ TEST_F(LogTest, ReadPastEnd) { CheckOffsetPastEndReturnsNoRecords(5); }
 
 }  // namespace log
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/db/memtable.cc b/db/memtable.cc
index f42774d..4f09340 100644
--- a/db/memtable.cc
+++ b/db/memtable.cc
@@ -78,6 +78,7 @@ void MemTable::Add(SequenceNumber s, ValueType type, const Slice& key,
   // Format of an entry is concatenation of:
   //  key_size     : varint32 of internal_key.size()
   //  key bytes    : char[internal_key.size()]
+  //  tag          : uint64((sequence << 8) | type)
   //  value_size   : varint32 of value.size()
   //  value bytes  : char[value.size()]
   size_t key_size = key.size();
diff --git a/db/memtable.h b/db/memtable.h
index 1099504..9d986b1 100644
--- a/db/memtable.h
+++ b/db/memtable.h
@@ -5,12 +5,11 @@
 #ifndef STORAGE_LEVELDB_DB_MEMTABLE_H_
 #define STORAGE_LEVELDB_DB_MEMTABLE_H_
 
-#include "db/dbformat.h"
-#include "db/skiplist.h"
 #include <string>
 
+#include "db/dbformat.h"
+#include "db/skiplist.h"
 #include "leveldb/db.h"
-
 #include "util/arena.h"
 
 namespace leveldb {
diff --git a/db/recovery_test.cc b/db/recovery_test.cc
index 6c5d42e..1d9f621 100644
--- a/db/recovery_test.cc
+++ b/db/recovery_test.cc
@@ -332,8 +332,3 @@ TEST_F(RecoveryTest, ManifestMissing) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/db/skiplist.cuh b/db/skiplist.cuh
index 2501af8..6f0cc6c 100644
--- a/db/skiplist.cuh
+++ b/db/skiplist.cuh
@@ -327,7 +327,7 @@ __device__ int SkipList<Key, Comparator>::RandomHeight() {
   // Increase height with probability 1 in kBranching
   static const unsigned int kBranching = 4;
   int height = 1;
-  while (height < kMaxHeight && ((rnd_.Next() % kBranching) == 0)) {
+  while (height < kMaxHeight && rnd_.OneIn(kBranching)) {
     height++;
   }
   assert(height > 0);
diff --git a/db/skiplist.h b/db/skiplist.h
index a59b45b..1140e59 100644
--- a/db/skiplist.h
+++ b/db/skiplist.h
@@ -36,8 +36,6 @@
 
 namespace leveldb {
 
-class Arena;
-
 template <typename Key, class Comparator>
 class SkipList {
  private:
@@ -243,7 +241,7 @@ int SkipList<Key, Comparator>::RandomHeight() {
   // Increase height with probability 1 in kBranching
   static const unsigned int kBranching = 4;
   int height = 1;
-  while (height < kMaxHeight && ((rnd_.Next() % kBranching) == 0)) {
+  while (height < kMaxHeight && rnd_.OneIn(kBranching)) {
     height++;
   }
   assert(height > 0);
diff --git a/db/snapshot.h b/db/snapshot.h
index 9f1d664..817bb7b 100644
--- a/db/snapshot.h
+++ b/db/snapshot.h
@@ -25,7 +25,7 @@ class SnapshotImpl : public Snapshot {
   friend class SnapshotList;
 
   // SnapshotImpl is kept in a doubly-linked circular list. The SnapshotList
-  // implementation operates on the next/previous fields direcly.
+  // implementation operates on the next/previous fields directly.
   SnapshotImpl* prev_;
   SnapshotImpl* next_;
 
diff --git a/db/table_cache.h b/db/table_cache.h
index aac9bfc..db8a123 100644
--- a/db/table_cache.h
+++ b/db/table_cache.h
@@ -22,6 +22,10 @@ class Env;
 class TableCache {
  public:
   TableCache(const std::string& dbname, const Options& options, int entries);
+
+  TableCache(const TableCache&) = delete;
+  TableCache& operator=(const TableCache&) = delete;
+
   ~TableCache();
 
   // Return an iterator for the specified file number (the corresponding
diff --git a/db/version_edit.cc b/db/version_edit.cc
index 3e9012f..356ce88 100644
--- a/db/version_edit.cc
+++ b/db/version_edit.cc
@@ -34,6 +34,7 @@ void VersionEdit::Clear() {
   has_prev_log_number_ = false;
   has_next_file_number_ = false;
   has_last_sequence_ = false;
+  compact_pointers_.clear();
   deleted_files_.clear();
   new_files_.clear();
 }
diff --git a/db/version_edit_test.cc b/db/version_edit_test.cc
index acafab0..a108c15 100644
--- a/db/version_edit_test.cc
+++ b/db/version_edit_test.cc
@@ -39,8 +39,3 @@ TEST(VersionEditTest, EncodeDecode) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/db/version_set.cc b/db/version_set.cc
index 8d85fce..4e37bf9 100644
--- a/db/version_set.cc
+++ b/db/version_set.cc
@@ -626,7 +626,7 @@ class VersionSet::Builder {
   }
 
   // Apply all of the edits in *edit to the current state.
-  void Apply(VersionEdit* edit) {
+  void Apply(const VersionEdit* edit) {
     // Update compaction pointers
     for (size_t i = 0; i < edit->compact_pointers_.size(); i++) {
       const int level = edit->compact_pointers_[i].first;
@@ -806,7 +806,6 @@ Status VersionSet::LogAndApply(VersionEdit* edit, port::Mutex* mu) {
     // first call to LogAndApply (when opening the database).
     assert(descriptor_file_ == nullptr);
     new_manifest_file = DescriptorFileName(dbname_, manifest_file_number_);
-    edit->SetNextFile(next_file_number_);
     s = env_->NewWritableFile(new_manifest_file, &descriptor_file_);
     if (s.ok()) {
       descriptor_log_ = new log::Writer(descriptor_file_);
@@ -1304,7 +1303,7 @@ Compaction* VersionSet::PickCompaction() {
   return c;
 }
 
-// Finds the largest key in a vector of files. Returns true if files it not
+// Finds the largest key in a vector of files. Returns true if files is not
 // empty.
 bool FindLargestKey(const InternalKeyComparator& icmp,
                     const std::vector<FileMetaData*>& files,
diff --git a/db/version_set.h b/db/version_set.h
index 69f3d70..ea0c925 100644
--- a/db/version_set.h
+++ b/db/version_set.h
@@ -59,9 +59,6 @@ bool SomeFileOverlapsRange(const InternalKeyComparator& icmp,
 
 class Version {
  public:
-  // Lookup the value for key.  If found, store it in *val and
-  // return OK.  Else return a non-OK status.  Fills *stats.
-  // REQUIRES: lock is not held
   struct GetStats {
     FileMetaData* seek_file;
     int seek_file_level;
@@ -72,6 +69,9 @@ class Version {
   // REQUIRES: This version has been saved (see VersionSet::SaveTo)
   void AddIterators(const ReadOptions&, std::vector<Iterator*>* iters);
 
+  // Lookup the value for key.  If found, store it in *val and
+  // return OK.  Else return a non-OK status.  Fills *stats.
+  // REQUIRES: lock is not held
   Status Get(const ReadOptions&, const LookupKey& key, std::string* val,
              GetStats* stats);
 
diff --git a/db/version_set_test.cc b/db/version_set_test.cc
index dee6b4c..64bb983 100644
--- a/db/version_set_test.cc
+++ b/db/version_set_test.cc
@@ -329,8 +329,3 @@ TEST_F(AddBoundaryInputsTest, TestDisjoinFilePointers) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/db/write_batch_test.cc b/db/write_batch_test.cc
index 64df9b8..1a3ea8f 100644
--- a/db/write_batch_test.cc
+++ b/db/write_batch_test.cc
@@ -130,8 +130,3 @@ TEST(WriteBatchTest, ApproximateSize) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/doc/benchmark.html b/doc/benchmark.html
index 1e0b4ef..80e6c2a 100644
--- a/doc/benchmark.html
+++ b/doc/benchmark.html
@@ -90,9 +90,9 @@ div.bsql {
 <h4>Benchmark Source Code</h4>
 <p>We wrote benchmark tools for SQLite and Kyoto TreeDB based on LevelDB's <span class="code">db_bench</span>. The code for each of the benchmarks resides here:</p>
 <ul>
-	<li> <b>LevelDB:</b> <a href="https://github.com/google/leveldb/blob/master/benchmarks/db_bench.cc">benchmarks/db_bench.cc</a>.</li>
-	<li> <b>SQLite:</b> <a href="https://github.com/google/leveldb/blob/master/benchmarks/db_bench_sqlite3.cc">benchmarks/db_bench_sqlite3.cc</a>.</li>
-	<li> <b>Kyoto TreeDB:</b> <a href="https://github.com/google/leveldb/blob/master/benchmarks/db_bench_tree_db.cc">benchmarks/db_bench_tree_db.cc</a>.</li>
+	<li> <b>LevelDB:</b> <a href="https://github.com/google/leveldb/blob/main/benchmarks/db_bench.cc">benchmarks/db_bench.cc</a>.</li>
+	<li> <b>SQLite:</b> <a href="https://github.com/google/leveldb/blob/main/benchmarks/db_bench_sqlite3.cc">benchmarks/db_bench_sqlite3.cc</a>.</li>
+	<li> <b>Kyoto TreeDB:</b> <a href="https://github.com/google/leveldb/blob/main/benchmarks/db_bench_tree_db.cc">benchmarks/db_bench_tree_db.cc</a>.</li>
 </ul>
 
 <h4>Custom Build Specifications</h4>
diff --git a/doc/index.md b/doc/index.md
index 01693ad..0f6d649 100644
--- a/doc/index.md
+++ b/doc/index.md
@@ -369,6 +369,7 @@ leveldb::Iterator* it = db->NewIterator(options);
 for (it->SeekToFirst(); it->Valid(); it->Next()) {
   ...
 }
+delete it;
 ```
 
 ### Key Layout
@@ -424,21 +425,21 @@ spaces. For example:
 ```c++
 class CustomFilterPolicy : public leveldb::FilterPolicy {
  private:
-  FilterPolicy* builtin_policy_;
+  leveldb::FilterPolicy* builtin_policy_;
 
  public:
-  CustomFilterPolicy() : builtin_policy_(NewBloomFilterPolicy(10)) {}
+  CustomFilterPolicy() : builtin_policy_(leveldb::NewBloomFilterPolicy(10)) {}
   ~CustomFilterPolicy() { delete builtin_policy_; }
 
   const char* Name() const { return "IgnoreTrailingSpacesFilter"; }
 
-  void CreateFilter(const Slice* keys, int n, std::string* dst) const {
+  void CreateFilter(const leveldb::Slice* keys, int n, std::string* dst) const {
     // Use builtin bloom filter code after removing trailing spaces
-    std::vector<Slice> trimmed(n);
+    std::vector<leveldb::Slice> trimmed(n);
     for (int i = 0; i < n; i++) {
       trimmed[i] = RemoveTrailingSpaces(keys[i]);
     }
-    return builtin_policy_->CreateFilter(trimmed.data(), n, dst);
+    builtin_policy_->CreateFilter(trimmed.data(), n, dst);
   }
 };
 ```
diff --git a/helpers/memenv/memenv_test.cc b/helpers/memenv/memenv_test.cc
index 3f03cb6..909a0ca 100644
--- a/helpers/memenv/memenv_test.cc
+++ b/helpers/memenv/memenv_test.cc
@@ -257,8 +257,3 @@ TEST_F(MemEnvTest, DBTest) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/include/leveldb/cache.h b/include/leveldb/cache.h
index 98c95ac..a94c683 100644
--- a/include/leveldb/cache.h
+++ b/include/leveldb/cache.h
@@ -96,14 +96,6 @@ class LEVELDB_EXPORT Cache {
   // Return an estimate of the combined charges of all elements stored in the
   // cache.
   virtual size_t TotalCharge() const = 0;
-
- private:
-  void LRU_Remove(Handle* e);
-  void LRU_Append(Handle* e);
-  void Unref(Handle* e);
-
-  struct Rep;
-  Rep* rep_;
 };
 
 }  // namespace leveldb
diff --git a/issues/issue178_test.cc b/issues/issue178_test.cc
index 8fa5bb9..5cd5862 100644
--- a/issues/issue178_test.cc
+++ b/issues/issue178_test.cc
@@ -83,8 +83,3 @@ TEST(Issue178, Test) {
 }
 
 }  // anonymous namespace
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/issues/issue200_test.cc b/issues/issue200_test.cc
index 4eba23a..959b371 100644
--- a/issues/issue200_test.cc
+++ b/issues/issue200_test.cc
@@ -52,8 +52,3 @@ TEST(Issue200, Test) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/issues/issue320_test.cc b/issues/issue320_test.cc
index c08296a..9d7fa7b 100644
--- a/issues/issue320_test.cc
+++ b/issues/issue320_test.cc
@@ -124,8 +124,3 @@ TEST(Issue320, Test) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/port/port_example.h b/port/port_example.h
index a665910..704aa24 100644
--- a/port/port_example.h
+++ b/port/port_example.h
@@ -55,7 +55,7 @@ class CondVar {
   void Signal();
 
   // Wake up all waiting threads.
-  void SignallAll();
+  void SignalAll();
 };
 
 // ------------------ Compression -------------------
diff --git a/table/filter_block_test.cc b/table/filter_block_test.cc
index 91a6be2..3ee41cf 100644
--- a/table/filter_block_test.cc
+++ b/table/filter_block_test.cc
@@ -120,8 +120,3 @@ TEST_F(FilterBlockTest, MultiChunk) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/table/table_test.cc b/table/table_test.cc
index 190dd0f..7f0f998 100644
--- a/table/table_test.cc
+++ b/table/table_test.cc
@@ -827,8 +827,3 @@ TEST(TableTest, ApproximateOffsetOfCompressed) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/util/arena.cc b/util/arena.cc
index 41c6a0d..d3ec2be 100644
--- a/util/arena.cc
+++ b/util/arena.cc
@@ -14,7 +14,7 @@ Arena::Arena()
 Arena::~Arena() {
   for (size_t i = 0; i < blocks_.size(); i++) {
     //cudaFree(blocks_[i]);
-    delete [] blocks_[i];
+    delete[] blocks_[i];
   }
 }
 
diff --git a/util/arena_test.cc b/util/arena_test.cc
index d2ead39..3e2011e 100644
--- a/util/arena_test.cc
+++ b/util/arena_test.cc
@@ -3,9 +3,9 @@
 // found in the LICENSE file. See the AUTHORS file for names of contributors.
 
 #include "util/arena.h"
-#include "util/random.h"
 
 #include "gtest/gtest.h"
+#include "util/random.h"
 
 namespace leveldb {
 
@@ -59,8 +59,3 @@ TEST(ArenaTest, Simple) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/util/bloom_test.cc b/util/bloom_test.cc
index 520473e..9f11108 100644
--- a/util/bloom_test.cc
+++ b/util/bloom_test.cc
@@ -152,8 +152,3 @@ TEST_F(BloomTest, VaryingLengths) {
 // Different bits-per-byte
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/util/cache.cc b/util/cache.cc
index ad1e9a2..fc3d154 100644
--- a/util/cache.cc
+++ b/util/cache.cc
@@ -54,7 +54,7 @@ struct LRUHandle {
   char key_data[1];  // Beginning of key
 
   Slice key() const {
-    // next_ is only equal to this if the LRU handle is the list head of an
+    // next is only equal to this if the LRU handle is the list head of an
     // empty list. List heads never have meaningful keys.
     assert(next != this);
 
diff --git a/util/cache_test.cc b/util/cache_test.cc
index 79cfc27..e68da34 100644
--- a/util/cache_test.cc
+++ b/util/cache_test.cc
@@ -222,8 +222,3 @@ TEST_F(CacheTest, ZeroSizeCache) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/util/coding.cc b/util/coding.cc
index df3fa10..a8f8af8 100644
--- a/util/coding.cc
+++ b/util/coding.cc
@@ -142,16 +142,6 @@ bool GetVarint64(Slice* input, uint64_t* value) {
   }
 }
 
-const char* GetLengthPrefixedSlice(const char* p, const char* limit,
-                                   Slice* result) {
-  uint32_t len;
-  p = GetVarint32Ptr(p, limit, &len);
-  if (p == nullptr) return nullptr;
-  if (p + len > limit) return nullptr;
-  *result = Slice(p, len);
-  return p + len;
-}
-
 bool GetLengthPrefixedSlice(Slice* input, Slice* result) {
   uint32_t len;
   if (GetVarint32(input, &len) && input->size() >= len) {
diff --git a/util/coding_test.cc b/util/coding_test.cc
index aa6c748..cceda14 100644
--- a/util/coding_test.cc
+++ b/util/coding_test.cc
@@ -191,8 +191,3 @@ TEST(Coding, Strings) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/util/crc32c_test.cc b/util/crc32c_test.cc
index 647e561..2fe1c41 100644
--- a/util/crc32c_test.cc
+++ b/util/crc32c_test.cc
@@ -54,8 +54,3 @@ TEST(CRC, Mask) {
 
 }  // namespace crc32c
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/util/env_posix.cc b/util/env_posix.cc
index 24b1c4c..ffd06c4 100644
--- a/util/env_posix.cc
+++ b/util/env_posix.cc
@@ -4,7 +4,6 @@
 
 #include <dirent.h>
 #include <fcntl.h>
-#include <pthread.h>
 #include <sys/mman.h>
 #ifndef __Fuchsia__
 #include <sys/resource.h>
@@ -74,7 +73,14 @@ Status PosixError(const std::string& context, int error_number) {
 class Limiter {
  public:
   // Limit maximum number of resources to |max_acquires|.
-  Limiter(int max_acquires) : acquires_allowed_(max_acquires) {}
+  Limiter(int max_acquires)
+      :
+#if !defined(NDEBUG)
+        max_acquires_(max_acquires),
+#endif  // !defined(NDEBUG)
+        acquires_allowed_(max_acquires) {
+    assert(max_acquires >= 0);
+  }
 
   Limiter(const Limiter&) = delete;
   Limiter operator=(const Limiter&) = delete;
@@ -87,15 +93,35 @@ class Limiter {
 
     if (old_acquires_allowed > 0) return true;
 
-    acquires_allowed_.fetch_add(1, std::memory_order_relaxed);
+    int pre_increment_acquires_allowed =
+        acquires_allowed_.fetch_add(1, std::memory_order_relaxed);
+
+    // Silence compiler warnings about unused arguments when NDEBUG is defined.
+    (void)pre_increment_acquires_allowed;
+    // If the check below fails, Release() was called more times than acquire.
+    assert(pre_increment_acquires_allowed < max_acquires_);
+
     return false;
   }
 
   // Release a resource acquired by a previous call to Acquire() that returned
   // true.
-  void Release() { acquires_allowed_.fetch_add(1, std::memory_order_relaxed); }
+  void Release() {
+    int old_acquires_allowed =
+        acquires_allowed_.fetch_add(1, std::memory_order_relaxed);
+
+    // Silence compiler warnings about unused arguments when NDEBUG is defined.
+    (void)old_acquires_allowed;
+    // If the check below fails, Release() was called more times than acquire.
+    assert(old_acquires_allowed < max_acquires_);
+  }
 
  private:
+#if !defined(NDEBUG)
+  // Catches an excessive number of Release() calls.
+  const int max_acquires_;
+#endif  // !defined(NDEBUG)
+
   // The number of available resources.
   //
   // This is a counter and is not tied to the invariants of any other class, so
@@ -110,7 +136,7 @@ class Limiter {
 class PosixSequentialFile final : public SequentialFile {
  public:
   PosixSequentialFile(std::string filename, int fd)
-      : fd_(fd), filename_(filename) {}
+      : fd_(fd), filename_(std::move(filename)) {}
   ~PosixSequentialFile() override { close(fd_); }
 
   Status Read(size_t n, Slice* result, char* scratch) override {
@@ -216,7 +242,7 @@ class PosixMmapReadableFile final : public RandomAccessFile {
   // over the ownership of the region.
   //
   // |mmap_limiter| must outlive this instance. The caller must have already
-  // aquired the right to use one mmap region, which will be released when this
+  // acquired the right to use one mmap region, which will be released when this
   // instance is destroyed.
   PosixMmapReadableFile(std::string filename, char* mmap_base, size_t length,
                         Limiter* mmap_limiter)
@@ -730,7 +756,7 @@ class PosixEnv : public Env {
   // Instances are constructed on the thread calling Schedule() and used on the
   // background thread.
   //
-  // This structure is thread-safe beacuse it is immutable.
+  // This structure is thread-safe because it is immutable.
   struct BackgroundWorkItem {
     explicit BackgroundWorkItem(void (*function)(void* arg), void* arg)
         : function(function), arg(arg) {}
@@ -844,7 +870,7 @@ class SingletonEnv {
  public:
   SingletonEnv() {
 #if !defined(NDEBUG)
-    env_initialized_.store(true, std::memory_order::memory_order_relaxed);
+    env_initialized_.store(true, std::memory_order_relaxed);
 #endif  // !defined(NDEBUG)
     static_assert(sizeof(env_storage_) >= sizeof(EnvType),
                   "env_storage_ will not fit the Env");
@@ -861,7 +887,7 @@ class SingletonEnv {
 
   static void AssertEnvNotInitialized() {
 #if !defined(NDEBUG)
-    assert(!env_initialized_.load(std::memory_order::memory_order_relaxed));
+    assert(!env_initialized_.load(std::memory_order_relaxed));
 #endif  // !defined(NDEBUG)
   }
 
diff --git a/util/env_posix_test.cc b/util/env_posix_test.cc
index da264f0..34bda62 100644
--- a/util/env_posix_test.cc
+++ b/util/env_posix_test.cc
@@ -243,8 +243,8 @@ TEST_F(EnvPosixTest, TestCloseOnExecRandomAccessFile) {
   // Exhaust the RandomAccessFile mmap limit. This way, the test
   // RandomAccessFile instance below is backed by a file descriptor, not by an
   // mmap region.
-  leveldb::RandomAccessFile* mmapped_files[kReadOnlyFileLimit] = {nullptr};
-  for (int i = 0; i < kReadOnlyFileLimit; i++) {
+  leveldb::RandomAccessFile* mmapped_files[kMMapLimit];
+  for (int i = 0; i < kMMapLimit; i++) {
     ASSERT_LEVELDB_OK(env_->NewRandomAccessFile(file_path, &mmapped_files[i]));
   }
 
@@ -253,7 +253,7 @@ TEST_F(EnvPosixTest, TestCloseOnExecRandomAccessFile) {
   CheckCloseOnExecDoesNotLeakFDs(open_fds);
   delete file;
 
-  for (int i = 0; i < kReadOnlyFileLimit; i++) {
+  for (int i = 0; i < kMMapLimit; i++) {
     delete mmapped_files[i];
   }
   ASSERT_LEVELDB_OK(env_->RemoveFile(file_path));
diff --git a/util/env_test.cc b/util/env_test.cc
index 491ef43..47174f5 100644
--- a/util/env_test.cc
+++ b/util/env_test.cc
@@ -14,8 +14,6 @@
 
 namespace leveldb {
 
-static const int kDelayMicros = 100000;
-
 class EnvTest : public testing::Test {
  public:
   EnvTest() : env_(Env::Default()) {}
@@ -233,8 +231,3 @@ TEST_F(EnvTest, ReopenAppendableFile) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/util/env_windows.cc b/util/env_windows.cc
index 449f564..1c74b02 100644
--- a/util/env_windows.cc
+++ b/util/env_windows.cc
@@ -114,7 +114,14 @@ class ScopedHandle {
 class Limiter {
  public:
   // Limit maximum number of resources to |max_acquires|.
-  Limiter(int max_acquires) : acquires_allowed_(max_acquires) {}
+  Limiter(int max_acquires)
+      :
+#if !defined(NDEBUG)
+        max_acquires_(max_acquires),
+#endif  // !defined(NDEBUG)
+        acquires_allowed_(max_acquires) {
+    assert(max_acquires >= 0);
+  }
 
   Limiter(const Limiter&) = delete;
   Limiter operator=(const Limiter&) = delete;
@@ -133,9 +140,22 @@ class Limiter {
 
   // Release a resource acquired by a previous call to Acquire() that returned
   // true.
-  void Release() { acquires_allowed_.fetch_add(1, std::memory_order_relaxed); }
+  void Release() {
+    int old_acquires_allowed =
+        acquires_allowed_.fetch_add(1, std::memory_order_relaxed);
+
+    // Silence compiler warnings about unused arguments when NDEBUG is defined.
+    (void)old_acquires_allowed;
+    // If the check below fails, Release() was called more times than acquire.
+    assert(old_acquires_allowed < max_acquires_);
+  }
 
  private:
+#if !defined(NDEBUG)
+  // Catches an excessive number of Release() calls.
+  const int max_acquires_;
+#endif  // !defined(NDEBUG)
+
   // The number of available resources.
   //
   // This is a counter and is not tied to the invariants of any other class, so
@@ -622,7 +642,7 @@ class WindowsEnv : public Env {
   }
 
   Status NewLogger(const std::string& filename, Logger** result) override {
-    std::FILE* fp = std::fopen(filename.c_str(), "w");
+    std::FILE* fp = std::fopen(filename.c_str(), "wN");
     if (fp == nullptr) {
       *result = nullptr;
       return WindowsError(filename, ::GetLastError());
@@ -661,7 +681,7 @@ class WindowsEnv : public Env {
   // Instances are constructed on the thread calling Schedule() and used on the
   // background thread.
   //
-  // This structure is thread-safe beacuse it is immutable.
+  // This structure is thread-safe because it is immutable.
   struct BackgroundWorkItem {
     explicit BackgroundWorkItem(void (*function)(void* arg), void* arg)
         : function(function), arg(arg) {}
@@ -745,7 +765,7 @@ class SingletonEnv {
  public:
   SingletonEnv() {
 #if !defined(NDEBUG)
-    env_initialized_.store(true, std::memory_order::memory_order_relaxed);
+    env_initialized_.store(true, std::memory_order_relaxed);
 #endif  // !defined(NDEBUG)
     static_assert(sizeof(env_storage_) >= sizeof(EnvType),
                   "env_storage_ will not fit the Env");
@@ -762,7 +782,7 @@ class SingletonEnv {
 
   static void AssertEnvNotInitialized() {
 #if !defined(NDEBUG)
-    assert(!env_initialized_.load(std::memory_order::memory_order_relaxed));
+    assert(!env_initialized_.load(std::memory_order_relaxed));
 #endif  // !defined(NDEBUG)
   }
 
diff --git a/util/hash_test.cc b/util/hash_test.cc
index 6d6771f..0ea5977 100644
--- a/util/hash_test.cc
+++ b/util/hash_test.cc
@@ -39,8 +39,3 @@ TEST(HASH, SignedUnsignedIssue) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/util/logging_test.cc b/util/logging_test.cc
index 24e1fe9..1746c57 100644
--- a/util/logging_test.cc
+++ b/util/logging_test.cc
@@ -138,8 +138,3 @@ TEST(Logging, ConsumeDecimalNumberNoDigits) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/util/no_destructor_test.cc b/util/no_destructor_test.cc
index 68fdfee..e3602cc 100644
--- a/util/no_destructor_test.cc
+++ b/util/no_destructor_test.cc
@@ -42,8 +42,3 @@ TEST(NoDestructorTest, StaticInstance) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}
diff --git a/util/random.h b/util/random.h
index d7cbdd9..60ca9ed 100644
--- a/util/random.h
+++ b/util/random.h
@@ -57,8 +57,6 @@ class Random {
   // range [0,2^max_log-1] with exponential bias towards smaller numbers.
   uint32_t Skewed(int max_log) { return Uniform(1 << Uniform(max_log + 1)); }
 };
-
-
 }  // namespace leveldb
 
 #endif  // STORAGE_LEVELDB_UTIL_RANDOM_H_
diff --git a/util/status_test.cc b/util/status_test.cc
index 914b386..dbf5faa 100644
--- a/util/status_test.cc
+++ b/util/status_test.cc
@@ -37,8 +37,3 @@ TEST(Status, MoveConstructor) {
 }
 
 }  // namespace leveldb
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}