Release 1.18v1.18

Changes are:

* Update version number to 1.18
* Replace the basic fprintf call with a call to fwrite in order to
  work around the apparent compiler optimization/rewrite failure that we are
  seeing with the new toolchain/iOS SDKs provided with Xcode6 and iOS8.
* Fix ALL the header guards.
* Createed a README.md with the LevelDB project description.
* A new CONTRIBUTING file.
* Don't implicitly convert uint64_t to size_t or int.  Either preserve it as
  uint64_t, or explicitly cast. This fixes MSVC warnings about possible value
  truncation when compiling this code in Chromium.
* Added a DumpFile() library function that encapsulates the guts of the
  "leveldbutil dump" command. This will allow clients to dump
  data to their log files instead of stdout. It will also allow clients to
  supply their own environment.
* leveldb: Remove unused function 'ConsumeChar'.
* leveldbutil: Remove unused member variables from WriteBatchItemPrinter.
* OpenBSD, NetBSD and DragonflyBSD have _LITTLE_ENDIAN, so define
  PLATFORM_IS_LITTLE_ENDIAN like on FreeBSD. This fixes:
   * issue #143
   * issue #198
   * issue #249
* Switch from <cstdatomic> to <atomic>. The former never made it into the
  standard and doesn't exist in modern gcc versions at all.  The later contains
  everything that leveldb was using from the former.
  This problem was noticed when porting to Portable Native Client where no memory
  barrier is defined.  The fact that <cstdatomic> is missing normally goes
  unnoticed since memory barriers are defined for most architectures.
* Make Hash() treat its input as unsigned.  Before this change LevelDB files
  from platforms with different signedness of char were not compatible. This
  change fixes: issue #243
* Verify checksums of index/meta/filter blocks when paranoid_checks set.
* Invoke all tools for iOS with xcrun. (This was causing problems with the new
  XCode 5.1.1 image on pulse.)
* include <sys/stat.h> only once, and fix the following linter warning:
  "Found C system header after C++ system header"
* When encountering a corrupted table file, return Status::Corruption instead of
  Status::InvalidArgument.
* Support cygwin as build platform, patch is from https://code.google.com/p/leveldb/issues/detail?id=188
* Fix typo, merge patch from https://code.google.com/p/leveldb/issues/detail?id=159
* Fix typos and comments, and address the following two issues:
  * issue #166
  * issue #241
* Add missing db synchronize after "fillseq" in the benchmark.
* Removed unused variable in SeekRandom: value (issue #201)

13 files changed, 263 insertions, 208 deletions

diff --git a/db/db_bench.cc b/db/db_bench.cc
index fc46d89..705a170 100644
--- a/db/db_bench.cc
+++ b/db/db_bench.cc
@@ -431,7 +431,7 @@ class Benchmark {
         benchmarks = sep + 1;
       }
 
-      // Reset parameters that may be overriddden bwlow
+      // Reset parameters that may be overridden below
       num_ = FLAGS_num;
       reads_ = (FLAGS_reads < 0 ? FLAGS_num : FLAGS_reads);
       value_size_ = FLAGS_value_size;
@@ -811,7 +811,6 @@ class Benchmark {
 
   void SeekRandom(ThreadState* thread) {
     ReadOptions options;
-    std::string value;
     int found = 0;
     for (int i = 0; i < reads_; i++) {
       Iterator* iter = db_->NewIterator(options);
diff --git a/db/db_impl.cc b/db/db_impl.cc
index faf5e7d..49b9595 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -392,7 +392,7 @@ Status DBImpl::RecoverLogFile(uint64_t log_number,
   reporter.info_log = options_.info_log;
   reporter.fname = fname.c_str();
   reporter.status = (options_.paranoid_checks ? &status : NULL);
-  // We intentially make log::Reader do checksumming even if
+  // We intentionally make log::Reader do checksumming even if
   // paranoid_checks==false so that corruptions cause entire commits
   // to be skipped instead of propagating bad information (like overly
   // large sequence numbers).
@@ -1267,7 +1267,7 @@ WriteBatch* DBImpl::BuildBatchGroup(Writer** last_writer) {
         break;
       }
 
-      // Append to *reuslt
+      // Append to *result
       if (result == first->batch) {
         // Switch to temporary batch instead of disturbing caller's batch
         result = tmp_batch_;
diff --git a/db/db_test.cc b/db/db_test.cc
index 280b01c..0fed913 100644
--- a/db/db_test.cc
+++ b/db/db_test.cc
@@ -626,7 +626,7 @@ TEST(DBTest, GetEncountersEmptyLevel) {
     //   * sstable B in level 2
     // Then do enough Get() calls to arrange for an automatic compaction
     // of sstable A.  A bug would cause the compaction to be marked as
-    // occuring at level 1 (instead of the correct level 0).
+    // occurring at level 1 (instead of the correct level 0).
 
     // Step 1: First place sstables in levels 0 and 2
     int compaction_count = 0;
diff --git a/db/dbformat.h b/db/dbformat.h
index 5d8a032..ea897b1 100644
--- a/db/dbformat.h
+++ b/db/dbformat.h
@@ -2,8 +2,8 @@
 // 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.
 
-#ifndef STORAGE_LEVELDB_DB_FORMAT_H_
-#define STORAGE_LEVELDB_DB_FORMAT_H_
+#ifndef STORAGE_LEVELDB_DB_DBFORMAT_H_
+#define STORAGE_LEVELDB_DB_DBFORMAT_H_
 
 #include <stdio.h>
 #include "leveldb/comparator.h"
@@ -227,4 +227,4 @@ inline LookupKey::~LookupKey() {
 
 }  // namespace leveldb
 
-#endif  // STORAGE_LEVELDB_DB_FORMAT_H_
+#endif  // STORAGE_LEVELDB_DB_DBFORMAT_H_
diff --git a/db/dumpfile.cc b/db/dumpfile.cc
new file mode 100644
index 0000000..61c47c2
--- /dev/null
+++ b/db/dumpfile.cc
@@ -0,0 +1,225 @@
+// Copyright (c) 2012 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 <stdio.h>
+#include "db/dbformat.h"
+#include "db/filename.h"
+#include "db/log_reader.h"
+#include "db/version_edit.h"
+#include "db/write_batch_internal.h"
+#include "leveldb/env.h"
+#include "leveldb/iterator.h"
+#include "leveldb/options.h"
+#include "leveldb/status.h"
+#include "leveldb/table.h"
+#include "leveldb/write_batch.h"
+#include "util/logging.h"
+
+namespace leveldb {
+
+namespace {
+
+bool GuessType(const std::string& fname, FileType* type) {
+  size_t pos = fname.rfind('/');
+  std::string basename;
+  if (pos == std::string::npos) {
+    basename = fname;
+  } else {
+    basename = std::string(fname.data() + pos + 1, fname.size() - pos - 1);
+  }
+  uint64_t ignored;
+  return ParseFileName(basename, &ignored, type);
+}
+
+// Notified when log reader encounters corruption.
+class CorruptionReporter : public log::Reader::Reporter {
+ public:
+  WritableFile* dst_;
+  virtual void Corruption(size_t bytes, const Status& status) {
+    std::string r = "corruption: ";
+    AppendNumberTo(&r, bytes);
+    r += " bytes; ";
+    r += status.ToString();
+    r.push_back('\n');
+    dst_->Append(r);
+  }
+};
+
+// Print contents of a log file. (*func)() is called on every record.
+Status PrintLogContents(Env* env, const std::string& fname,
+                        void (*func)(uint64_t, Slice, WritableFile*),
+                        WritableFile* dst) {
+  SequentialFile* file;
+  Status s = env->NewSequentialFile(fname, &file);
+  if (!s.ok()) {
+    return s;
+  }
+  CorruptionReporter reporter;
+  reporter.dst_ = dst;
+  log::Reader reader(file, &reporter, true, 0);
+  Slice record;
+  std::string scratch;
+  while (reader.ReadRecord(&record, &scratch)) {
+    (*func)(reader.LastRecordOffset(), record, dst);
+  }
+  delete file;
+  return Status::OK();
+}
+
+// Called on every item found in a WriteBatch.
+class WriteBatchItemPrinter : public WriteBatch::Handler {
+ public:
+  WritableFile* dst_;
+  virtual void Put(const Slice& key, const Slice& value) {
+    std::string r = "  put '";
+    AppendEscapedStringTo(&r, key);
+    r += "' '";
+    AppendEscapedStringTo(&r, value);
+    r += "'\n";
+    dst_->Append(r);
+  }
+  virtual void Delete(const Slice& key) {
+    std::string r = "  del '";
+    AppendEscapedStringTo(&r, key);
+    r += "'\n";
+    dst_->Append(r);
+  }
+};
+
+
+// Called on every log record (each one of which is a WriteBatch)
+// found in a kLogFile.
+static void WriteBatchPrinter(uint64_t pos, Slice record, WritableFile* dst) {
+  std::string r = "--- offset ";
+  AppendNumberTo(&r, pos);
+  r += "; ";
+  if (record.size() < 12) {
+    r += "log record length ";
+    AppendNumberTo(&r, record.size());
+    r += " is too small\n";
+    dst->Append(r);
+    return;
+  }
+  WriteBatch batch;
+  WriteBatchInternal::SetContents(&batch, record);
+  r += "sequence ";
+  AppendNumberTo(&r, WriteBatchInternal::Sequence(&batch));
+  r.push_back('\n');
+  dst->Append(r);
+  WriteBatchItemPrinter batch_item_printer;
+  batch_item_printer.dst_ = dst;
+  Status s = batch.Iterate(&batch_item_printer);
+  if (!s.ok()) {
+    dst->Append("  error: " + s.ToString() + "\n");
+  }
+}
+
+Status DumpLog(Env* env, const std::string& fname, WritableFile* dst) {
+  return PrintLogContents(env, fname, WriteBatchPrinter, dst);
+}
+
+// Called on every log record (each one of which is a WriteBatch)
+// found in a kDescriptorFile.
+static void VersionEditPrinter(uint64_t pos, Slice record, WritableFile* dst) {
+  std::string r = "--- offset ";
+  AppendNumberTo(&r, pos);
+  r += "; ";
+  VersionEdit edit;
+  Status s = edit.DecodeFrom(record);
+  if (!s.ok()) {
+    r += s.ToString();
+    r.push_back('\n');
+  } else {
+    r += edit.DebugString();
+  }
+  dst->Append(r);
+}
+
+Status DumpDescriptor(Env* env, const std::string& fname, WritableFile* dst) {
+  return PrintLogContents(env, fname, VersionEditPrinter, dst);
+}
+
+Status DumpTable(Env* env, const std::string& fname, WritableFile* dst) {
+  uint64_t file_size;
+  RandomAccessFile* file = NULL;
+  Table* table = NULL;
+  Status s = env->GetFileSize(fname, &file_size);
+  if (s.ok()) {
+    s = env->NewRandomAccessFile(fname, &file);
+  }
+  if (s.ok()) {
+    // We use the default comparator, which may or may not match the
+    // comparator used in this database. However this should not cause
+    // problems since we only use Table operations that do not require
+    // any comparisons.  In particular, we do not call Seek or Prev.
+    s = Table::Open(Options(), file, file_size, &table);
+  }
+  if (!s.ok()) {
+    delete table;
+    delete file;
+    return s;
+  }
+
+  ReadOptions ro;
+  ro.fill_cache = false;
+  Iterator* iter = table->NewIterator(ro);
+  std::string r;
+  for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
+    r.clear();
+    ParsedInternalKey key;
+    if (!ParseInternalKey(iter->key(), &key)) {
+      r = "badkey '";
+      AppendEscapedStringTo(&r, iter->key());
+      r += "' => '";
+      AppendEscapedStringTo(&r, iter->value());
+      r += "'\n";
+      dst->Append(r);
+    } else {
+      r = "'";
+      AppendEscapedStringTo(&r, key.user_key);
+      r += "' @ ";
+      AppendNumberTo(&r, key.sequence);
+      r += " : ";
+      if (key.type == kTypeDeletion) {
+        r += "del";
+      } else if (key.type == kTypeValue) {
+        r += "val";
+      } else {
+        AppendNumberTo(&r, key.type);
+      }
+      r += " => '";
+      AppendEscapedStringTo(&r, iter->value());
+      r += "'\n";
+      dst->Append(r);
+    }
+  }
+  s = iter->status();
+  if (!s.ok()) {
+    dst->Append("iterator error: " + s.ToString() + "\n");
+  }
+
+  delete iter;
+  delete table;
+  delete file;
+  return Status::OK();
+}
+
+}  // namespace
+
+Status DumpFile(Env* env, const std::string& fname, WritableFile* dst) {
+  FileType ftype;
+  if (!GuessType(fname, &ftype)) {
+    return Status::InvalidArgument(fname + ": unknown file type");
+  }
+  switch (ftype) {
+    case kLogFile:         return DumpLog(env, fname, dst);
+    case kDescriptorFile:  return DumpDescriptor(env, fname, dst);
+    case kTableFile:       return DumpTable(env, fname, dst);
+    default:
+      break;
+  }
+  return Status::InvalidArgument(fname + ": not a dump-able file type");
+}
+
+}  // namespace leveldb
diff --git a/db/leveldb_main.cc b/db/leveldb_main.cc
index 995d761..9f4b7dd 100644
--- a/db/leveldb_main.cc
+++ b/db/leveldb_main.cc
@@ -3,212 +3,38 @@
 // found in the LICENSE file. See the AUTHORS file for names of contributors.
 
 #include <stdio.h>
-#include "db/dbformat.h"
-#include "db/filename.h"
-#include "db/log_reader.h"
-#include "db/version_edit.h"
-#include "db/write_batch_internal.h"
+#include "leveldb/dumpfile.h"
 #include "leveldb/env.h"
-#include "leveldb/iterator.h"
-#include "leveldb/options.h"
 #include "leveldb/status.h"
-#include "leveldb/table.h"
-#include "leveldb/write_batch.h"
-#include "util/logging.h"
 
 namespace leveldb {
-
 namespace {
 
-bool GuessType(const std::string& fname, FileType* type) {
-  size_t pos = fname.rfind('/');
-  std::string basename;
-  if (pos == std::string::npos) {
-    basename = fname;
-  } else {
-    basename = std::string(fname.data() + pos + 1, fname.size() - pos - 1);
-  }
-  uint64_t ignored;
-  return ParseFileName(basename, &ignored, type);
-}
-
-// Notified when log reader encounters corruption.
-class CorruptionReporter : public log::Reader::Reporter {
- public:
-  virtual void Corruption(size_t bytes, const Status& status) {
-    printf("corruption: %d bytes; %s\n",
-            static_cast<int>(bytes),
-            status.ToString().c_str());
-  }
-};
-
-// Print contents of a log file. (*func)() is called on every record.
-bool PrintLogContents(Env* env, const std::string& fname,
-                      void (*func)(Slice)) {
-  SequentialFile* file;
-  Status s = env->NewSequentialFile(fname, &file);
-  if (!s.ok()) {
-    fprintf(stderr, "%s\n", s.ToString().c_str());
-    return false;
-  }
-  CorruptionReporter reporter;
-  log::Reader reader(file, &reporter, true, 0);
-  Slice record;
-  std::string scratch;
-  while (reader.ReadRecord(&record, &scratch)) {
-    printf("--- offset %llu; ",
-           static_cast<unsigned long long>(reader.LastRecordOffset()));
-    (*func)(record);
-  }
-  delete file;
-  return true;
-}
-
-// Called on every item found in a WriteBatch.
-class WriteBatchItemPrinter : public WriteBatch::Handler {
+class StdoutPrinter : public WritableFile {
  public:
-  uint64_t offset_;
-  uint64_t sequence_;
-
-  virtual void Put(const Slice& key, const Slice& value) {
-    printf("  put '%s' '%s'\n",
-           EscapeString(key).c_str(),
-           EscapeString(value).c_str());
-  }
-  virtual void Delete(const Slice& key) {
-    printf("  del '%s'\n",
-           EscapeString(key).c_str());
+  virtual Status Append(const Slice& data) {
+    fwrite(data.data(), 1, data.size(), stdout);
+    return Status::OK();
   }
+  virtual Status Close() { return Status::OK(); }
+  virtual Status Flush() { return Status::OK(); }
+  virtual Status Sync() { return Status::OK(); }
 };
 
-
-// Called on every log record (each one of which is a WriteBatch)
-// found in a kLogFile.
-static void WriteBatchPrinter(Slice record) {
-  if (record.size() < 12) {
-    printf("log record length %d is too small\n",
-           static_cast<int>(record.size()));
-    return;
-  }
-  WriteBatch batch;
-  WriteBatchInternal::SetContents(&batch, record);
-  printf("sequence %llu\n",
-         static_cast<unsigned long long>(WriteBatchInternal::Sequence(&batch)));
-  WriteBatchItemPrinter batch_item_printer;
-  Status s = batch.Iterate(&batch_item_printer);
-  if (!s.ok()) {
-    printf("  error: %s\n", s.ToString().c_str());
-  }
-}
-
-bool DumpLog(Env* env, const std::string& fname) {
-  return PrintLogContents(env, fname, WriteBatchPrinter);
-}
-
-// Called on every log record (each one of which is a WriteBatch)
-// found in a kDescriptorFile.
-static void VersionEditPrinter(Slice record) {
-  VersionEdit edit;
-  Status s = edit.DecodeFrom(record);
-  if (!s.ok()) {
-    printf("%s\n", s.ToString().c_str());
-    return;
-  }
-  printf("%s", edit.DebugString().c_str());
-}
-
-bool DumpDescriptor(Env* env, const std::string& fname) {
-  return PrintLogContents(env, fname, VersionEditPrinter);
-}
-
-bool DumpTable(Env* env, const std::string& fname) {
-  uint64_t file_size;
-  RandomAccessFile* file = NULL;
-  Table* table = NULL;
-  Status s = env->GetFileSize(fname, &file_size);
-  if (s.ok()) {
-    s = env->NewRandomAccessFile(fname, &file);
-  }
-  if (s.ok()) {
-    // We use the default comparator, which may or may not match the
-    // comparator used in this database. However this should not cause
-    // problems since we only use Table operations that do not require
-    // any comparisons.  In particular, we do not call Seek or Prev.
-    s = Table::Open(Options(), file, file_size, &table);
-  }
-  if (!s.ok()) {
-    fprintf(stderr, "%s\n", s.ToString().c_str());
-    delete table;
-    delete file;
-    return false;
-  }
-
-  ReadOptions ro;
-  ro.fill_cache = false;
-  Iterator* iter = table->NewIterator(ro);
-  for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
-    ParsedInternalKey key;
-    if (!ParseInternalKey(iter->key(), &key)) {
-      printf("badkey '%s' => '%s'\n",
-             EscapeString(iter->key()).c_str(),
-             EscapeString(iter->value()).c_str());
-    } else {
-      char kbuf[20];
-      const char* type;
-      if (key.type == kTypeDeletion) {
-        type = "del";
-      } else if (key.type == kTypeValue) {
-        type = "val";
-      } else {
-        snprintf(kbuf, sizeof(kbuf), "%d", static_cast<int>(key.type));
-        type = kbuf;
-      }
-      printf("'%s' @ %8llu : %s => '%s'\n",
-             EscapeString(key.user_key).c_str(),
-             static_cast<unsigned long long>(key.sequence),
-             type,
-             EscapeString(iter->value()).c_str());
-    }
-  }
-  s = iter->status();
-  if (!s.ok()) {
-    printf("iterator error: %s\n", s.ToString().c_str());
-  }
-
-  delete iter;
-  delete table;
-  delete file;
-  return true;
-}
-
-bool DumpFile(Env* env, const std::string& fname) {
-  FileType ftype;
-  if (!GuessType(fname, &ftype)) {
-    fprintf(stderr, "%s: unknown file type\n", fname.c_str());
-    return false;
-  }
-  switch (ftype) {
-    case kLogFile:         return DumpLog(env, fname);
-    case kDescriptorFile:  return DumpDescriptor(env, fname);
-    case kTableFile:       return DumpTable(env, fname);
-
-    default: {
-      fprintf(stderr, "%s: not a dump-able file type\n", fname.c_str());
-      break;
-    }
-  }
-  return false;
-}
-
 bool HandleDumpCommand(Env* env, char** files, int num) {
+  StdoutPrinter printer;
   bool ok = true;
   for (int i = 0; i < num; i++) {
-    ok &= DumpFile(env, files[i]);
+    Status s = DumpFile(env, files[i], &printer);
+    if (!s.ok()) {
+      fprintf(stderr, "%s\n", s.ToString().c_str());
+      ok = false;
+    }
   }
   return ok;
 }
 
-}
+}  // namespace
 }  // namespace leveldb
 
 static void Usage() {
diff --git a/db/log_format.h b/db/log_format.h
index 2690cb9..a8c06ef 100644
--- a/db/log_format.h
+++ b/db/log_format.h
@@ -26,8 +26,8 @@ static const int kMaxRecordType = kLastType;
 
 static const int kBlockSize = 32768;
 
-// Header is checksum (4 bytes), type (1 byte), length (2 bytes).
-static const int kHeaderSize = 4 + 1 + 2;
+// Header is checksum (4 bytes), length (2 bytes), type (1 byte).
+static const int kHeaderSize = 4 + 2 + 1;
 
 }  // namespace log
 }  // namespace leveldb
diff --git a/db/log_reader.cc b/db/log_reader.cc
index 4919216..e44b66c 100644
--- a/db/log_reader.cc
+++ b/db/log_reader.cc
@@ -167,14 +167,14 @@ uint64_t Reader::LastRecordOffset() {
   return last_record_offset_;
 }
 
-void Reader::ReportCorruption(size_t bytes, const char* reason) {
+void Reader::ReportCorruption(uint64_t bytes, const char* reason) {
   ReportDrop(bytes, Status::Corruption(reason));
 }
 
-void Reader::ReportDrop(size_t bytes, const Status& reason) {
+void Reader::ReportDrop(uint64_t bytes, const Status& reason) {
   if (reporter_ != NULL &&
       end_of_buffer_offset_ - buffer_.size() - bytes >= initial_offset_) {
-    reporter_->Corruption(bytes, reason);
+    reporter_->Corruption(static_cast<size_t>(bytes), reason);
   }
 }
 
diff --git a/db/log_reader.h b/db/log_reader.h
index 82d4bee..6aff791 100644
--- a/db/log_reader.h
+++ b/db/log_reader.h
@@ -94,8 +94,8 @@ class Reader {
 
   // Reports dropped bytes to the reporter.
   // buffer_ must be updated to remove the dropped bytes prior to invocation.
-  void ReportCorruption(size_t bytes, const char* reason);
-  void ReportDrop(size_t bytes, const Status& reason);
+  void ReportCorruption(uint64_t bytes, const char* reason);
+  void ReportDrop(uint64_t bytes, const Status& reason);
 
   // No copying allowed
   Reader(const Reader&);
diff --git a/db/log_test.cc b/db/log_test.cc
index 91d3caa..dcf0562 100644
--- a/db/log_test.cc
+++ b/db/log_test.cc
@@ -463,7 +463,7 @@ TEST(LogTest, ErrorJoinsRecords) {
 
   ASSERT_EQ("correct", Read());
   ASSERT_EQ("EOF", Read());
-  const int dropped = DroppedBytes();
+  const size_t dropped = DroppedBytes();
   ASSERT_LE(dropped, 2*kBlockSize + 100);
   ASSERT_GE(dropped, 2*kBlockSize);
 }
diff --git a/db/repair.cc b/db/repair.cc
index 7727faf..4cd4bb0 100644
--- a/db/repair.cc
+++ b/db/repair.cc
@@ -186,7 +186,7 @@ class Repairer {
     reporter.env = env_;
     reporter.info_log = options_.info_log;
     reporter.lognum = log;
-    // We intentially make log::Reader do checksumming so that
+    // We intentionally make log::Reader do checksumming so that
     // corruptions cause entire commits to be skipped instead of
     // propagating bad information (like overly large sequence
     // numbers).
diff --git a/db/skiplist.h b/db/skiplist.h
index af85be6..ed8b092 100644
--- a/db/skiplist.h
+++ b/db/skiplist.h
@@ -1,3 +1,6 @@
+#ifndef STORAGE_LEVELDB_DB_SKIPLIST_H_
+#define STORAGE_LEVELDB_DB_SKIPLIST_H_
+
 // Copyright (c) 2011 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.
@@ -377,3 +380,5 @@ bool SkipList<Key,Comparator>::Contains(const Key& key) const {
 }
 
 }  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_DB_SKIPLIST_H_
diff --git a/db/write_batch_internal.h b/db/write_batch_internal.h
index 4423a7f..310a3c8 100644
--- a/db/write_batch_internal.h
+++ b/db/write_batch_internal.h
@@ -21,10 +21,10 @@ class WriteBatchInternal {
   // Set the count for the number of entries in the batch.
   static void SetCount(WriteBatch* batch, int n);
 
-  // Return the seqeunce number for the start of this batch.
+  // Return the sequence number for the start of this batch.
   static SequenceNumber Sequence(const WriteBatch* batch);
 
-  // Store the specified number as the seqeunce number for the start of
+  // Store the specified number as the sequence number for the start of
   // this batch.
   static void SetSequence(WriteBatch* batch, SequenceNumber seq);