Unrevert r245135 "Created new Windows LevelDB environment."

third_party/leveldatabase/env_chromium.cc

Index: third_party/leveldatabase/env_chromium.cc
diff --git a/third_party/leveldatabase/env_chromium.cc b/third_party/leveldatabase/env_chromium.cc
index b5a866c2918577d4e40bb057d9f4fd18ccfeb972..e3d5851a2f76e8c6d1e5f95d0d161aa0d9e848aa 100644
--- a/third_party/leveldatabase/env_chromium.cc
+++ b/third_party/leveldatabase/env_chromium.cc
@@ -2,9 +2,7 @@
 // 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 <errno.h>
 #include <stdio.h>
-#include <string.h>
 
 #include <deque>
 
@@ -26,6 +24,10 @@
 #include "base/threading/thread.h"
 #include "chromium_logger.h"
 #include "env_chromium.h"
+#include "env_chromium_posix.h"
+#if defined(OS_WIN)
+#include "env_chromium_win32.h"
+#endif
 #include "leveldb/env.h"
 #include "leveldb/slice.h"
 #include "port/port.h"
@@ -34,7 +36,10 @@
 
 #if defined(OS_WIN)
 #include <io.h>
+#include "base/command_line.h"
+#include "base/metrics/field_trial.h"
 #include "base/win/win_util.h"
+#include "leveldb_switches.h"
 #endif
 
 #if defined(OS_POSIX)
@@ -48,168 +53,25 @@ using namespace leveldb;
 
 namespace leveldb_env {
 
-namespace {
-
-const base::FilePath::CharType backup_table_extension[] =
-    FILE_PATH_LITERAL(".bak");
-const base::FilePath::CharType table_extension[] = FILE_PATH_LITERAL(".ldb");
-
-#if (defined(OS_POSIX) && !defined(OS_LINUX)) || defined(OS_WIN)
-// The following are glibc-specific
-
-size_t fread_unlocked(void *ptr, size_t size, size_t n, FILE *file) {
-  return fread(ptr, size, n, file);
-}
-
-size_t fwrite_unlocked(const void *ptr, size_t size, size_t n, FILE *file) {
-  return fwrite(ptr, size, n, file);
-}
-
-int fflush_unlocked(FILE *file) {
-  return fflush(file);
-}
-
-#if !defined(OS_ANDROID)
-int fdatasync(int fildes) {
+enum ChromiumEnvType {
+  CHROMIUM_ENV_UNSET
+  ,CHROMIUM_ENV_POSIX
 #if defined(OS_WIN)
-  return _commit(fildes);
-#else
-  return HANDLE_EINTR(fsync(fildes));
-#endif
-}
+  ,CHROMIUM_ENV_WIN32
 #endif
+};
 
-#endif
+static ChromiumEnvType g_active_chromium_env_type = CHROMIUM_ENV_UNSET;
 
-// Wide-char safe fopen wrapper.
-FILE* fopen_internal(const char* fname, const char* mode) {
-#if defined(OS_WIN)
-  return _wfopen(UTF8ToUTF16(fname).c_str(), ASCIIToUTF16(mode).c_str());
-#else
-  return fopen(fname, mode);
-#endif
-}
+namespace {
 
-base::FilePath CreateFilePath(const std::string& file_path) {
-#if defined(OS_WIN)
-  return base::FilePath(UTF8ToUTF16(file_path));
-#else
-  return base::FilePath(file_path);
-#endif
-}
+const base::FilePath::CharType backup_table_extension[] =
+    FILE_PATH_LITERAL(".bak");
+const base::FilePath::CharType table_extension[] = FILE_PATH_LITERAL(".ldb");
 
 static const base::FilePath::CharType kLevelDBTestDirectoryPrefix[]
     = FILE_PATH_LITERAL("leveldb-test-");
 
-const char* PlatformFileErrorString(const ::base::PlatformFileError& error) {
-  switch (error) {
-    case ::base::PLATFORM_FILE_ERROR_FAILED:
-      return "No further details.";
-    case ::base::PLATFORM_FILE_ERROR_IN_USE:
-      return "File currently in use.";
-    case ::base::PLATFORM_FILE_ERROR_EXISTS:
-      return "File already exists.";
-    case ::base::PLATFORM_FILE_ERROR_NOT_FOUND:
-      return "File not found.";
-    case ::base::PLATFORM_FILE_ERROR_ACCESS_DENIED:
-      return "Access denied.";
-    case ::base::PLATFORM_FILE_ERROR_TOO_MANY_OPENED:
-      return "Too many files open.";
-    case ::base::PLATFORM_FILE_ERROR_NO_MEMORY:
-      return "Out of memory.";
-    case ::base::PLATFORM_FILE_ERROR_NO_SPACE:
-      return "No space left on drive.";
-    case ::base::PLATFORM_FILE_ERROR_NOT_A_DIRECTORY:
-      return "Not a directory.";
-    case ::base::PLATFORM_FILE_ERROR_INVALID_OPERATION:
-      return "Invalid operation.";
-    case ::base::PLATFORM_FILE_ERROR_SECURITY:
-      return "Security error.";
-    case ::base::PLATFORM_FILE_ERROR_ABORT:
-      return "File operation aborted.";
-    case ::base::PLATFORM_FILE_ERROR_NOT_A_FILE:
-      return "The supplied path was not a file.";
-    case ::base::PLATFORM_FILE_ERROR_NOT_EMPTY:
-      return "The file was not empty.";
-    case ::base::PLATFORM_FILE_ERROR_INVALID_URL:
-      return "Invalid URL.";
-    case ::base::PLATFORM_FILE_ERROR_IO:
-      return "OS or hardware error.";
-    case ::base::PLATFORM_FILE_OK:
-      return "OK.";
-    case ::base::PLATFORM_FILE_ERROR_MAX:
-      NOTREACHED();
-  }
-  NOTIMPLEMENTED();
-  return "Unknown error.";
-}
-
-class ChromiumSequentialFile: public SequentialFile {
- private:
-  std::string filename_;
-  FILE* file_;
-  const UMALogger* uma_logger_;
-
- public:
-  ChromiumSequentialFile(const std::string& fname, FILE* f,
-                         const UMALogger* uma_logger)
-      : filename_(fname), file_(f), uma_logger_(uma_logger) { }
-  virtual ~ChromiumSequentialFile() { fclose(file_); }
-
-  virtual Status Read(size_t n, Slice* result, char* scratch) {
-    Status s;
-    size_t r = fread_unlocked(scratch, 1, n, file_);
-    *result = Slice(scratch, r);
-    if (r < n) {
-      if (feof(file_)) {
-        // We leave status as ok if we hit the end of the file
-      } else {
-        // A partial read with an error: return a non-ok status
-        s = MakeIOError(filename_, strerror(errno), kSequentialFileRead, errno);
-        uma_logger_->RecordErrorAt(kSequentialFileRead);
-      }
-    }
-    return s;
-  }
-
-  virtual Status Skip(uint64_t n) {
-    if (fseek(file_, n, SEEK_CUR)) {
-      int saved_errno = errno;
-      uma_logger_->RecordErrorAt(kSequentialFileSkip);
-      return MakeIOError(
-          filename_, strerror(saved_errno), kSequentialFileSkip, saved_errno);
-    }
-    return Status::OK();
-  }
-};
-
-class ChromiumRandomAccessFile: public RandomAccessFile {
- private:
-  std::string filename_;
-  ::base::PlatformFile file_;
-  const UMALogger* uma_logger_;
-
- public:
-  ChromiumRandomAccessFile(const std::string& fname, ::base::PlatformFile file,
-                           const UMALogger* uma_logger)
-      : filename_(fname), file_(file), uma_logger_(uma_logger) { }
-  virtual ~ChromiumRandomAccessFile() { ::base::ClosePlatformFile(file_); }
-
-  virtual Status Read(uint64_t offset, size_t n, Slice* result,
-                      char* scratch) const {
-    Status s;
-    int r = ::base::ReadPlatformFile(file_, offset, scratch, n);
-    *result = Slice(scratch, (r < 0) ? 0 : r);
-    if (r < 0) {
-      // An error: return a non-ok status
-      s = MakeIOError(
-          filename_, "Could not perform read", kRandomAccessFileRead);
-      uma_logger_->RecordErrorAt(kRandomAccessFileRead);
-    }
-    return s;
-  }
-};
-
 class ChromiumFileLock : public FileLock {
  public:
   ::base::PlatformFile file_;
@@ -260,18 +122,37 @@ class Retrier {
   RetrierProvider* provider_;
 };
 
-class IDBEnv : public ChromiumEnv {
+class IDBEnvPosix : public ChromiumEnvPosix {
+ public:
+  IDBEnvPosix() : ChromiumEnvPosix() {
+    name_ = "LevelDBEnv.IDB";
+    make_backup_ = true;
+  }
+};
+
+#if defined(OS_WIN)
+class IDBEnvWin32 : public ChromiumEnvWin32 {
  public:
-  IDBEnv() : ChromiumEnv() {
+  IDBEnvWin32() : ChromiumEnvWin32() {
     name_ = "LevelDBEnv.IDB";
     make_backup_ = true;
   }
 };
+#endif
+
+::base::LazyInstance<IDBEnvPosix>::Leaky idb_env_posix =
+    LAZY_INSTANCE_INITIALIZER;
+
+::base::LazyInstance<ChromiumEnvPosix>::Leaky default_env_posix =
+    LAZY_INSTANCE_INITIALIZER;
 
-::base::LazyInstance<IDBEnv>::Leaky idb_env = LAZY_INSTANCE_INITIALIZER;
+#if defined(OS_WIN)
+::base::LazyInstance<IDBEnvWin32>::Leaky idb_env_win32 =
+    LAZY_INSTANCE_INITIALIZER;
 
-::base::LazyInstance<ChromiumEnv>::Leaky default_env =
+::base::LazyInstance<ChromiumEnvWin32>::Leaky default_env_win32 =
     LAZY_INSTANCE_INITIALIZER;
+#endif
 
 }  // unnamed namespace
 
@@ -330,21 +211,6 @@ const char* MethodIDToString(MethodID method) {
 Status MakeIOError(Slice filename,
                    const char* message,
                    MethodID method,
-                   int saved_errno) {
-  char buf[512];
-  snprintf(buf,
-           sizeof(buf),
-           "%s (ChromeMethodErrno: %d::%s::%d)",
-           message,
-           method,
-           MethodIDToString(method),
-           saved_errno);
-  return Status::IOError(filename, buf);
-}
-
-Status MakeIOError(Slice filename,
-                   const char* message,
-                   MethodID method,
                    base::PlatformFileError error) {
   DCHECK(error < 0);
   char buf[512];
@@ -493,122 +359,24 @@ std::string FilePathToString(const base::FilePath& file_path) {
 #endif
 }
 
-ChromiumWritableFile::ChromiumWritableFile(const std::string& fname,
-                                           FILE* f,
-                                           const UMALogger* uma_logger,
-                                           WriteTracker* tracker,
-                                           bool make_backup)
-    : filename_(fname),
-      file_(f),
-      uma_logger_(uma_logger),
-      tracker_(tracker),
-      file_type_(kOther),
-      make_backup_(make_backup) {
-  base::FilePath path = base::FilePath::FromUTF8Unsafe(fname);
-  if (FilePathToString(path.BaseName()).find("MANIFEST") == 0)
-    file_type_ = kManifest;
-  else if (path.MatchesExtension(table_extension))
-    file_type_ = kTable;
-  if (file_type_ != kManifest)
-    tracker_->DidCreateNewFile(filename_);
-  parent_dir_ = FilePathToString(CreateFilePath(fname).DirName());
-}
-
-ChromiumWritableFile::~ChromiumWritableFile() {
-  if (file_ != NULL) {
-    // Ignoring any potential errors
-    fclose(file_);
-  }
-}
-
-Status ChromiumWritableFile::SyncParent() {
-  Status s;
-#if !defined(OS_WIN)
-  TRACE_EVENT0("leveldb", "SyncParent");
-
-  int parent_fd =
-      HANDLE_EINTR(open(parent_dir_.c_str(), O_RDONLY));
-  if (parent_fd < 0) {
-    int saved_errno = errno;
-    return MakeIOError(
-        parent_dir_, strerror(saved_errno), kSyncParent, saved_errno);
-  }
-  if (HANDLE_EINTR(fsync(parent_fd)) != 0) {
-    int saved_errno = errno;
-    s = MakeIOError(
-        parent_dir_, strerror(saved_errno), kSyncParent, saved_errno);
-  };
-  close(parent_fd);
+base::FilePath ChromiumEnv::CreateFilePath(const std::string& file_path) {
+#if defined(OS_WIN)
+  return base::FilePath(UTF8ToUTF16(file_path));
+#else
+  return base::FilePath(file_path);
 #endif
-  return s;
-}
-
-Status ChromiumWritableFile::Append(const Slice& data) {
-  if (file_type_ == kManifest && tracker_->DoesDirNeedSync(filename_)) {
-    Status s = SyncParent();
-    if (!s.ok())
-      return s;
-    tracker_->DidSyncDir(filename_);
-  }
-
-  size_t r = fwrite_unlocked(data.data(), 1, data.size(), file_);
-  if (r != data.size()) {
-    int saved_errno = errno;
-    uma_logger_->RecordOSError(kWritableFileAppend, saved_errno);
-    return MakeIOError(
-        filename_, strerror(saved_errno), kWritableFileAppend, saved_errno);
-  }
-  return Status::OK();
-}
-
-Status ChromiumWritableFile::Close() {
-  Status result;
-  if (fclose(file_) != 0) {
-    result = MakeIOError(filename_, strerror(errno), kWritableFileClose, errno);
-    uma_logger_->RecordErrorAt(kWritableFileClose);
-  }
-  file_ = NULL;
-  return result;
-}
-
-Status ChromiumWritableFile::Flush() {
-  Status result;
-  if (HANDLE_EINTR(fflush_unlocked(file_))) {
-    int saved_errno = errno;
-    result = MakeIOError(
-        filename_, strerror(saved_errno), kWritableFileFlush, saved_errno);
-    uma_logger_->RecordOSError(kWritableFileFlush, saved_errno);
-  }
-  return result;
 }
 
-static bool MakeBackup(const std::string& fname) {
+bool ChromiumEnv::MakeBackup(const std::string& fname) {
   base::FilePath original_table_name = CreateFilePath(fname);
   base::FilePath backup_table_name =
       original_table_name.ReplaceExtension(backup_table_extension);
   return base::CopyFile(original_table_name, backup_table_name);
 }
 
-Status ChromiumWritableFile::Sync() {
-  TRACE_EVENT0("leveldb", "ChromiumEnv::Sync");
-  Status result;
-  int error = 0;
-
-  if (HANDLE_EINTR(fflush_unlocked(file_)))
-    error = errno;
-  // Sync even if fflush gave an error; perhaps the data actually got out,
-  // even though something went wrong.
-  if (fdatasync(fileno(file_)) && !error)
-    error = errno;
-  // Report the first error we found.
-  if (error) {
-    result = MakeIOError(filename_, strerror(error), kWritableFileSync, error);
-    uma_logger_->RecordErrorAt(kWritableFileSync);
-  } else if (make_backup_ && file_type_ == kTable) {
-    bool success = MakeBackup(filename_);
-    uma_logger_->RecordBackupResult(success);
-  }
-  return result;
+bool ChromiumEnv::HasTableExtension(const base::FilePath& path)
+{
+  return path.MatchesExtension(table_extension);
 }
 
 ChromiumEnv::ChromiumEnv()
@@ -625,71 +393,55 @@ ChromiumEnv::~ChromiumEnv() {
   // a unit test that is deleted.
 }
 
-Status ChromiumEnv::NewSequentialFile(const std::string& fname,
-                                      SequentialFile** result) {
-  FILE* f = fopen_internal(fname.c_str(), "rb");
-  if (f == NULL) {
-    *result = NULL;
-    int saved_errno = errno;
-    RecordOSError(kNewSequentialFile, saved_errno);
-    return MakeIOError(
-        fname, strerror(saved_errno), kNewSequentialFile, saved_errno);
-  } else {
-    *result = new ChromiumSequentialFile(fname, f, this);
-    return Status::OK();
-  }
-}
-
-void ChromiumEnv::RecordOpenFilesLimit(const std::string& type) {
-#if defined(OS_POSIX)
-  struct rlimit nofile;
-  if (getrlimit(RLIMIT_NOFILE, &nofile))
-    return;
-  GetMaxFDHistogram(type)->Add(nofile.rlim_cur);
-#endif
+void ChromiumEnv::SetDelegate(ChromiumEnvDelegate* delegate) {
+  env_delegate_.reset(delegate);
 }
 
-Status ChromiumEnv::NewRandomAccessFile(const std::string& fname,
-                                        RandomAccessFile** result) {
-  int flags = ::base::PLATFORM_FILE_READ | ::base::PLATFORM_FILE_OPEN;
-  bool created;
-  ::base::PlatformFileError error_code;
-  ::base::PlatformFile file = ::base::CreatePlatformFile(
-      CreateFilePath(fname), flags, &created, &error_code);
-  if (error_code == ::base::PLATFORM_FILE_OK) {
-    *result = new ChromiumRandomAccessFile(fname, file, this);
-    RecordOpenFilesLimit("Success");
-    return Status::OK();
-  }
-  if (error_code == ::base::PLATFORM_FILE_ERROR_TOO_MANY_OPENED)
-    RecordOpenFilesLimit("TooManyOpened");
-  else
-    RecordOpenFilesLimit("OtherError");
-  *result = NULL;
-  RecordOSError(kNewRandomAccessFile, error_code);
-  return MakeIOError(fname,
-                     PlatformFileErrorString(error_code),
-                     kNewRandomAccessFile,
-                     error_code);
+bool ChromiumEnv::FileExists(const std::string& fname) {
+  return ::base::PathExists(CreateFilePath(fname));
 }
 
-Status ChromiumEnv::NewWritableFile(const std::string& fname,
-                                    WritableFile** result) {
-  *result = NULL;
-  FILE* f = fopen_internal(fname.c_str(), "wb");
-  if (f == NULL) {
-    int saved_errno = errno;
-    RecordErrorAt(kNewWritableFile);
-    return MakeIOError(
-        fname, strerror(saved_errno), kNewWritableFile, saved_errno);
-  } else {
-    *result = new ChromiumWritableFile(fname, f, this, this, make_backup_);
-    return Status::OK();
+const char* ChromiumEnv::PlatformFileErrorString(const ::base::PlatformFileError& error) {
+  switch (error) {
+    case ::base::PLATFORM_FILE_ERROR_FAILED:
+      return "No further details.";
+    case ::base::PLATFORM_FILE_ERROR_IN_USE:
+      return "File currently in use.";
+    case ::base::PLATFORM_FILE_ERROR_EXISTS:
+      return "File already exists.";
+    case ::base::PLATFORM_FILE_ERROR_NOT_FOUND:
+      return "File not found.";
+    case ::base::PLATFORM_FILE_ERROR_ACCESS_DENIED:
+      return "Access denied.";
+    case ::base::PLATFORM_FILE_ERROR_TOO_MANY_OPENED:
+      return "Too many files open.";
+    case ::base::PLATFORM_FILE_ERROR_NO_MEMORY:
+      return "Out of memory.";
+    case ::base::PLATFORM_FILE_ERROR_NO_SPACE:
+      return "No space left on drive.";
+    case ::base::PLATFORM_FILE_ERROR_NOT_A_DIRECTORY:
+      return "Not a directory.";
+    case ::base::PLATFORM_FILE_ERROR_INVALID_OPERATION:
+      return "Invalid operation.";
+    case ::base::PLATFORM_FILE_ERROR_SECURITY:
+      return "Security error.";
+    case ::base::PLATFORM_FILE_ERROR_ABORT:
+      return "File operation aborted.";
+    case ::base::PLATFORM_FILE_ERROR_NOT_A_FILE:
+      return "The supplied path was not a file.";
+    case ::base::PLATFORM_FILE_ERROR_NOT_EMPTY:
+      return "The file was not empty.";
+    case ::base::PLATFORM_FILE_ERROR_INVALID_URL:
+      return "Invalid URL.";
+    case ::base::PLATFORM_FILE_ERROR_IO:
+      return "OS or hardware error.";
+    case ::base::PLATFORM_FILE_OK:
+      return "OK.";
+    case ::base::PLATFORM_FILE_ERROR_MAX:
+      NOTREACHED();
   }
-}
-
-bool ChromiumEnv::FileExists(const std::string& fname) {
-  return ::base::PathExists(CreateFilePath(fname));
+  NOTIMPLEMENTED();
+  return "Unknown error.";
 }
 
 base::FilePath ChromiumEnv::RestoreFromBackup(const base::FilePath& base_name) {
@@ -745,62 +497,6 @@ void ChromiumEnv::RestoreIfNecessary(const std::string& dir,
   }
 }
 
-namespace {
-#if defined(OS_WIN)
-static base::PlatformFileError GetDirectoryEntries(
-    const base::FilePath& dir_param,
-    std::vector<base::FilePath>* result) {
-  result->clear();
-  base::FilePath dir_filepath = dir_param.Append(FILE_PATH_LITERAL("*"));
-  WIN32_FIND_DATA find_data;
-  HANDLE find_handle = FindFirstFile(dir_filepath.value().c_str(), &find_data);
-  if (find_handle == INVALID_HANDLE_VALUE) {
-    DWORD last_error = GetLastError();
-    if (last_error == ERROR_FILE_NOT_FOUND)
-      return base::PLATFORM_FILE_OK;
-    return base::LastErrorToPlatformFileError(last_error);
-  }
-  do {
-    base::FilePath filepath(find_data.cFileName);
-    base::FilePath::StringType basename = filepath.BaseName().value();
-    if (basename == FILE_PATH_LITERAL(".") ||
-        basename == FILE_PATH_LITERAL(".."))
-      continue;
-    result->push_back(filepath.BaseName());
-  } while (FindNextFile(find_handle, &find_data));
-  DWORD last_error = GetLastError();
-  base::PlatformFileError return_value = base::PLATFORM_FILE_OK;
-  if (last_error != ERROR_NO_MORE_FILES)
-    return_value = base::LastErrorToPlatformFileError(last_error);
-  FindClose(find_handle);
-  return return_value;
-}
-#else
-static base::PlatformFileError GetDirectoryEntries(
-    const base::FilePath& dir_filepath,
-    std::vector<base::FilePath>* result) {
-  const std::string dir_string = FilePathToString(dir_filepath);
-  result->clear();
-  DIR* dir = opendir(dir_string.c_str());
-  if (!dir)
-    return base::ErrnoToPlatformFileError(errno);
-  struct dirent dent_buf;
-  struct dirent* dent;
-  int readdir_result;
-  while ((readdir_result = readdir_r(dir, &dent_buf, &dent)) == 0 && dent) {
-    if (strcmp(dent->d_name, ".") == 0 || strcmp(dent->d_name, "..") == 0)
-      continue;
-    result->push_back(CreateFilePath(dent->d_name));
-  }
-  int saved_errno = errno;
-  closedir(dir);
-  if (readdir_result != 0)
-    return base::ErrnoToPlatformFileError(saved_errno);
-  return base::PLATFORM_FILE_OK;
-}
-#endif
-}
-
 Status ChromiumEnv::GetChildren(const std::string& dir_string,
                                 std::vector<std::string>* result) {
   std::vector<base::FilePath> entries;
@@ -1001,19 +697,6 @@ Status ChromiumEnv::GetTestDirectory(std::string* path) {
   return Status::OK();
 }
 
-Status ChromiumEnv::NewLogger(const std::string& fname, Logger** result) {
-  FILE* f = fopen_internal(fname.c_str(), "w");
-  if (f == NULL) {
-    *result = NULL;
-    int saved_errno = errno;
-    RecordOSError(kNewLogger, saved_errno);
-    return MakeIOError(fname, strerror(saved_errno), kNewLogger, saved_errno);
-  } else {
-    *result = new ChromiumLogger(f);
-    return Status::OK();
-  }
-}
-
 uint64_t ChromiumEnv::NowMicros() {
   return ::base::TimeTicks::Now().ToInternalValue();
 }
@@ -1199,18 +882,83 @@ bool ChromiumEnv::DoesDirNeedSync(const std::string& filename) {
 void ChromiumEnv::DidSyncDir(const std::string& filename) {
   base::AutoLock auto_lock(map_lock_);
   needs_sync_map_.erase(GetDirName(filename));
+  if (env_delegate_)
+    env_delegate_->DidSyncDir(filename);
 }
 
 }  // namespace leveldb_env
 
 namespace leveldb {
 
+#if defined(OS_WIN)
+static std::string GetFieldTrialDbEnvType() {
+  static const char kFieldTrialName[] = "LevelDbEnvWin32";
+  return base::FieldTrialList::FindFullName(kFieldTrialName);
+}
+#endif
+
+static void SetEnvType() {
+  DCHECK(leveldb_env::g_active_chromium_env_type ==
+         leveldb_env::CHROMIUM_ENV_UNSET);
+#if defined(OS_WIN)
+  const CommandLine* command_line = CommandLine::ForCurrentProcess();
+  const std::string env_type_switch =
+      command_line->HasSwitch(switches::kLevelDbEnv) ?
+      command_line->GetSwitchValueASCII(switches::kLevelDbEnv) :
+      switches::kLevelDbEnvDefault;
+  if (env_type_switch == switches::kLevelDbEnvWin32) {
+    leveldb_env::g_active_chromium_env_type = leveldb_env::CHROMIUM_ENV_WIN32;
+  }
+  else if (env_type_switch == switches::kLevelDbEnvPosix) {
+    leveldb_env::g_active_chromium_env_type = leveldb_env::CHROMIUM_ENV_POSIX;
+  }
+  else {
+    if (GetFieldTrialDbEnvType() == switches::kLevelDbEnvWin32)
+      leveldb_env::g_active_chromium_env_type = leveldb_env::CHROMIUM_ENV_WIN32;
+    else
+      leveldb_env::g_active_chromium_env_type = leveldb_env::CHROMIUM_ENV_POSIX;
+  }
+#else
+  leveldb_env::g_active_chromium_env_type = leveldb_env::CHROMIUM_ENV_POSIX;
+#endif
+}
+
 Env* IDBEnv() {
-  return leveldb_env::idb_env.Pointer();
+
+  if (leveldb_env::g_active_chromium_env_type ==
+      leveldb_env::CHROMIUM_ENV_UNSET)
+    SetEnvType();
+
+  switch (leveldb_env::g_active_chromium_env_type) {
+    case leveldb_env::CHROMIUM_ENV_POSIX:
+      return leveldb_env::idb_env_posix.Pointer();
+#if defined(OS_WIN)
+    case leveldb_env::CHROMIUM_ENV_WIN32:
+      return leveldb_env::idb_env_win32.Pointer();
+#endif
+    default:
+      DCHECK(false);
+      return NULL;
+  }
 }
 
 Env* Env::Default() {
-  return leveldb_env::default_env.Pointer();
+
+  if (leveldb_env::g_active_chromium_env_type ==
+      leveldb_env::CHROMIUM_ENV_UNSET)
+    SetEnvType();
+
+  switch (leveldb_env::g_active_chromium_env_type) {
+    case leveldb_env::CHROMIUM_ENV_POSIX:
+      return leveldb_env::default_env_posix.Pointer();
+#if defined(OS_WIN)
+    case leveldb_env::CHROMIUM_ENV_WIN32:
+      return leveldb_env::default_env_win32.Pointer();
+#endif
+    default:
+      DCHECK(false);
+      return NULL;
+  }
 }
 
 }  // namespace leveldb