third_party/leveldatabase/env_chromium.h

   1 // Copyright (c) 2013 The LevelDB Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file. See the AUTHORS file for names of contributors.
   4
   5 #ifndef THIRD_PARTY_LEVELDATABASE_ENV_CHROMIUM_H_
   6 #define THIRD_PARTY_LEVELDATABASE_ENV_CHROMIUM_H_
   7
   8 #include <deque>
   9 #include <set>
  10 #include <string>
  11 #include <vector>
  12
  13 #include "base/files/file.h"
  14 #include "base/files/file_path.h"
  15 #include "base/metrics/histogram.h"
  16 #include "leveldb/env.h"
  17 #include "port/port_chromium.h"
  18 #include "util/mutexlock.h"
  19
  20 namespace leveldb_env {
  21
  22 // These entries map to values in tools/metrics/histograms/histograms.xml. New
  23 // values should be appended at the end.
  24 enum MethodID {
  25   kSequentialFileRead,
  26   kSequentialFileSkip,
  27   kRandomAccessFileRead,
  28   kWritableFileAppend,
  29   kWritableFileClose,
  30   kWritableFileFlush,
  31   kWritableFileSync,
  32   kNewSequentialFile,
  33   kNewRandomAccessFile,
  34   kNewWritableFile,
  35   kDeleteFile,
  36   kCreateDir,
  37   kDeleteDir,
  38   kGetFileSize,
  39   kRenameFile,
  40   kLockFile,
  41   kUnlockFile,
  42   kGetTestDirectory,
  43   kNewLogger,
  44   kSyncParent,
  45   kGetChildren,
  46   kNewAppendableFile,
  47   kNumEntries
  48 };
  49
  50 // The default value for leveldb::Options::reuse_logs. Currently log reuse is an
  51 // experimental feature in leveldb. More info at:
  52 // https://github.com/google/leveldb/commit/251ebf5dc70129ad3
  53 const bool kDefaultLogReuseOptionValue = true;
  54
  55 const char* MethodIDToString(MethodID method);
  56
  57 leveldb::Status MakeIOError(leveldb::Slice filename,
  58                             const std::string& message,
  59                             MethodID method,
  60                             base::File::Error error);
  61 leveldb::Status MakeIOError(leveldb::Slice filename,
  62                             const std::string& message,
  63                             MethodID method);
  64
  65 enum ErrorParsingResult {
  66   METHOD_ONLY,
  67   METHOD_AND_BFE,
  68   NONE,
  69 };
  70
  71 ErrorParsingResult ParseMethodAndError(const leveldb::Status& status,
  72                                        MethodID* method,
  73                                        base::File::Error* error);
  74 int GetCorruptionCode(const leveldb::Status& status);
  75 int GetNumCorruptionCodes();
  76 std::string GetCorruptionMessage(const leveldb::Status& status);
  77 bool IndicatesDiskFull(const leveldb::Status& status);
  78
  79 class UMALogger {
  80  public:
  81   virtual void RecordErrorAt(MethodID method) const = 0;
  82   virtual void RecordOSError(MethodID method,
  83                              base::File::Error error) const = 0;
  84   virtual void RecordBackupResult(bool success) const = 0;
  85 };
  86
  87 class RetrierProvider {
  88  public:
  89   virtual int MaxRetryTimeMillis() const = 0;
  90   virtual base::HistogramBase* GetRetryTimeHistogram(MethodID method) const = 0;
  91   virtual base::HistogramBase* GetRecoveredFromErrorHistogram(
  92       MethodID method) const = 0;
  93 };
  94
  95 class ChromiumEnv : public leveldb::Env,
  96                     public UMALogger,
  97                     public RetrierProvider {
  98  public:
  99   ChromiumEnv();
 100
 101   typedef void(ScheduleFunc)(void*);
 102
 103   static bool MakeBackup(const std::string& fname);
 104   virtual ~ChromiumEnv();
 105
 106   virtual bool FileExists(const std::string& fname);
 107   virtual leveldb::Status GetChildren(const std::string& dir,
 108                                       std::vector<std::string>* result);
 109   virtual leveldb::Status DeleteFile(const std::string& fname);
 110   virtual leveldb::Status CreateDir(const std::string& name);
 111   virtual leveldb::Status DeleteDir(const std::string& name);
 112   virtual leveldb::Status GetFileSize(const std::string& fname, uint64_t* size);
 113   virtual leveldb::Status RenameFile(const std::string& src,
 114                                      const std::string& dst);
 115   virtual leveldb::Status LockFile(const std::string& fname,
 116                                    leveldb::FileLock** lock);
 117   virtual leveldb::Status UnlockFile(leveldb::FileLock* lock);
 118   virtual void Schedule(ScheduleFunc*, void* arg);
 119   virtual void StartThread(void (*function)(void* arg), void* arg);
 120   virtual leveldb::Status GetTestDirectory(std::string* path);
 121   virtual uint64_t NowMicros();
 122   virtual void SleepForMicroseconds(int micros);
 123   virtual leveldb::Status NewSequentialFile(const std::string& fname,
 124                                             leveldb::SequentialFile** result);
 125   virtual leveldb::Status NewRandomAccessFile(
 126       const std::string& fname,
 127       leveldb::RandomAccessFile** result);
 128   virtual leveldb::Status NewWritableFile(const std::string& fname,
 129                                           leveldb::WritableFile** result);
 130   virtual leveldb::Status NewAppendableFile(const std::string& fname,
 131                                             leveldb::WritableFile** result);
 132   virtual leveldb::Status NewLogger(const std::string& fname,
 133                                     leveldb::Logger** result);
 134
 135  protected:
 136   std::string name_;
 137   std::string uma_ioerror_base_name_;
 138   bool make_backup_;
 139
 140  private:
 141   static const char* FileErrorString(base::File::Error error);
 142
 143   virtual void RecordErrorAt(MethodID method) const;
 144   virtual void RecordOSError(MethodID method,
 145                              base::File::Error error) const;
 146   void RecordOpenFilesLimit(const std::string& type);
 147   base::HistogramBase* GetMaxFDHistogram(const std::string& type) const;
 148   base::HistogramBase* GetOSErrorHistogram(MethodID method, int limit) const;
 149
 150   // File locks may not be exclusive within a process (e.g. on POSIX). Track
 151   // locks held by the ChromiumEnv to prevent access within the process.
 152   class LockTable {
 153    public:
 154     bool Insert(const std::string& fname) {
 155       leveldb::MutexLock l(&mu_);
 156       return locked_files_.insert(fname).second;
 157     }
 158     bool Remove(const std::string& fname) {
 159       leveldb::MutexLock l(&mu_);
 160       return locked_files_.erase(fname) == 1;
 161     }
 162    private:
 163     leveldb::port::Mutex mu_;
 164     std::set<std::string> locked_files_;
 165   };
 166
 167   const int kMaxRetryTimeMillis;
 168   // BGThread() is the body of the background thread
 169   void BGThread();
 170   static void BGThreadWrapper(void* arg) {
 171     reinterpret_cast<ChromiumEnv*>(arg)->BGThread();
 172   }
 173
 174   virtual void RecordBackupResult(bool result) const;
 175   void RestoreIfNecessary(const std::string& dir,
 176                           std::vector<std::string>* children);
 177   base::FilePath RestoreFromBackup(const base::FilePath& base_name);
 178   void RecordLockFileAncestors(int num_missing_ancestors) const;
 179   base::HistogramBase* GetMethodIOErrorHistogram() const;
 180   base::HistogramBase* GetLockFileAncestorHistogram() const;
 181
 182   // RetrierProvider implementation.
 183   virtual int MaxRetryTimeMillis() const { return kMaxRetryTimeMillis; }
 184   virtual base::HistogramBase* GetRetryTimeHistogram(MethodID method) const;
 185   virtual base::HistogramBase* GetRecoveredFromErrorHistogram(
 186       MethodID method) const;
 187
 188   base::FilePath test_directory_;
 189
 190   base::Lock mu_;
 191   base::ConditionVariable bgsignal_;
 192   bool started_bgthread_;
 193
 194   // Entry per Schedule() call
 195   struct BGItem {
 196     void* arg;
 197     void (*function)(void*);
 198   };
 199   typedef std::deque<BGItem> BGQueue;
 200   BGQueue queue_;
 201   LockTable locks_;
 202 };
 203
 204 }  // namespace leveldb_env
 205
 206 #endif  // THIRD_PARTY_LEVELDATABASE_ENV_CHROMIUM_H_