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 const char* MethodIDToString(MethodID method);
  51
  52 leveldb::Status MakeIOError(leveldb::Slice filename,
  53                             const std::string& message,
  54                             MethodID method,
  55                             base::File::Error error);
  56 leveldb::Status MakeIOError(leveldb::Slice filename,
  57                             const std::string& message,
  58                             MethodID method);
  59
  60 enum ErrorParsingResult {
  61   METHOD_ONLY,
  62   METHOD_AND_PFE,
  63   NONE,
  64 };
  65
  66 ErrorParsingResult ParseMethodAndError(const leveldb::Status& status,
  67                                        MethodID* method,
  68                                        base::File::Error* error);
  69 int GetCorruptionCode(const leveldb::Status& status);
  70 int GetNumCorruptionCodes();
  71 std::string GetCorruptionMessage(const leveldb::Status& status);
  72 bool IndicatesDiskFull(const leveldb::Status& status);
  73
  74 class UMALogger {
  75  public:
  76   virtual void RecordErrorAt(MethodID method) const = 0;
  77   virtual void RecordOSError(MethodID method,
  78                              base::File::Error error) const = 0;
  79   virtual void RecordBackupResult(bool success) const = 0;
  80 };
  81
  82 class RetrierProvider {
  83  public:
  84   virtual int MaxRetryTimeMillis() const = 0;
  85   virtual base::HistogramBase* GetRetryTimeHistogram(MethodID method) const = 0;
  86   virtual base::HistogramBase* GetRecoveredFromErrorHistogram(
  87       MethodID method) const = 0;
  88 };
  89
  90 class WriteTracker {
  91  public:
  92   virtual void DidCreateNewFile(const std::string& fname) = 0;
  93   virtual bool DoesDirNeedSync(const std::string& fname) = 0;
  94   virtual void DidSyncDir(const std::string& fname) = 0;
  95 };
  96
  97 class ChromiumEnv : public leveldb::Env,
  98                     public UMALogger,
  99                     public RetrierProvider,
 100                     public WriteTracker {
 101  public:
 102   ChromiumEnv();
 103
 104   typedef void(ScheduleFunc)(void*);
 105
 106   static bool MakeBackup(const std::string& fname);
 107   virtual ~ChromiumEnv();
 108
 109   virtual bool FileExists(const std::string& fname);
 110   virtual leveldb::Status GetChildren(const std::string& dir,
 111                                       std::vector<std::string>* result);
 112   virtual leveldb::Status DeleteFile(const std::string& fname);
 113   virtual leveldb::Status CreateDir(const std::string& name);
 114   virtual leveldb::Status DeleteDir(const std::string& name);
 115   virtual leveldb::Status GetFileSize(const std::string& fname, uint64_t* size);
 116   virtual leveldb::Status RenameFile(const std::string& src,
 117                                      const std::string& dst);
 118   virtual leveldb::Status LockFile(const std::string& fname,
 119                                    leveldb::FileLock** lock);
 120   virtual leveldb::Status UnlockFile(leveldb::FileLock* lock);
 121   virtual void Schedule(ScheduleFunc*, void* arg);
 122   virtual void StartThread(void (*function)(void* arg), void* arg);
 123   virtual leveldb::Status GetTestDirectory(std::string* path);
 124   virtual uint64_t NowMicros();
 125   virtual void SleepForMicroseconds(int micros);
 126   virtual leveldb::Status NewSequentialFile(const std::string& fname,
 127                                             leveldb::SequentialFile** result);
 128   virtual leveldb::Status NewRandomAccessFile(
 129       const std::string& fname,
 130       leveldb::RandomAccessFile** result);
 131   virtual leveldb::Status NewWritableFile(const std::string& fname,
 132                                           leveldb::WritableFile** result);
 133   virtual leveldb::Status NewAppendableFile(const std::string& fname,
 134                                             leveldb::WritableFile** result);
 135   virtual leveldb::Status NewLogger(const std::string& fname,
 136                                     leveldb::Logger** result);
 137
 138  protected:
 139   virtual void DidSyncDir(const std::string& fname);
 140
 141   std::string name_;
 142   bool make_backup_;
 143
 144  private:
 145   static const char* FileErrorString(base::File::Error error);
 146
 147   virtual void DidCreateNewFile(const std::string& fname);
 148   virtual bool DoesDirNeedSync(const std::string& fname);
 149   virtual void RecordErrorAt(MethodID method) const;
 150   virtual void RecordOSError(MethodID method,
 151                              base::File::Error error) const;
 152   void RecordOpenFilesLimit(const std::string& type);
 153   base::HistogramBase* GetMaxFDHistogram(const std::string& type) const;
 154   base::HistogramBase* GetOSErrorHistogram(MethodID method, int limit) const;
 155
 156   // File locks may not be exclusive within a process (e.g. on POSIX). Track
 157   // locks held by the ChromiumEnv to prevent access within the process.
 158   class LockTable {
 159    public:
 160     bool Insert(const std::string& fname) {
 161       leveldb::MutexLock l(&mu_);
 162       return locked_files_.insert(fname).second;
 163     }
 164     bool Remove(const std::string& fname) {
 165       leveldb::MutexLock l(&mu_);
 166       return locked_files_.erase(fname) == 1;
 167     }
 168    private:
 169     leveldb::port::Mutex mu_;
 170     std::set<std::string> locked_files_;
 171   };
 172
 173   std::set<std::string> directories_needing_sync_;
 174   base::Lock directory_sync_lock_;
 175
 176   const int kMaxRetryTimeMillis;
 177   // BGThread() is the body of the background thread
 178   void BGThread();
 179   static void BGThreadWrapper(void* arg) {
 180     reinterpret_cast<ChromiumEnv*>(arg)->BGThread();
 181   }
 182
 183   virtual void RecordBackupResult(bool result) const;
 184   void RestoreIfNecessary(const std::string& dir,
 185                           std::vector<std::string>* children);
 186   base::FilePath RestoreFromBackup(const base::FilePath& base_name);
 187   void RecordLockFileAncestors(int num_missing_ancestors) const;
 188   base::HistogramBase* GetMethodIOErrorHistogram() const;
 189   base::HistogramBase* GetLockFileAncestorHistogram() const;
 190
 191   // RetrierProvider implementation.
 192   virtual int MaxRetryTimeMillis() const { return kMaxRetryTimeMillis; }
 193   virtual base::HistogramBase* GetRetryTimeHistogram(MethodID method) const;
 194   virtual base::HistogramBase* GetRecoveredFromErrorHistogram(
 195       MethodID method) const;
 196
 197   base::FilePath test_directory_;
 198
 199   base::Lock mu_;
 200   base::ConditionVariable bgsignal_;
 201   bool started_bgthread_;
 202
 203   // Entry per Schedule() call
 204   struct BGItem {
 205     void* arg;
 206     void (*function)(void*);
 207   };
 208   typedef std::deque<BGItem> BGQueue;
 209   BGQueue queue_;
 210   LockTable locks_;
 211 };
 212
 213 }  // namespace leveldb_env
 214
 215 #endif  // THIRD_PARTY_LEVELDATABASE_ENV_CHROMIUM_H_