Bitcoin Core  0.18.99
P2P Digital Currency
dbwrapper.cpp
Go to the documentation of this file.
1 // Copyright (c) 2012-2018 The Bitcoin Core developers
2 // Distributed under the MIT software license, see the accompanying
3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
4 
5 #include <dbwrapper.h>
6 
7 #include <memory>
8 #include <random.h>
9 
10 #include <leveldb/cache.h>
11 #include <leveldb/env.h>
12 #include <leveldb/filter_policy.h>
13 #include <memenv.h>
14 #include <stdint.h>
15 #include <algorithm>
16 
17 class CBitcoinLevelDBLogger : public leveldb::Logger {
18 public:
19  // This code is adapted from posix_logger.h, which is why it is using vsprintf.
20  // Please do not do this in normal code
21  void Logv(const char * format, va_list ap) override {
23  return;
24  }
25  char buffer[500];
26  for (int iter = 0; iter < 2; iter++) {
27  char* base;
28  int bufsize;
29  if (iter == 0) {
30  bufsize = sizeof(buffer);
31  base = buffer;
32  }
33  else {
34  bufsize = 30000;
35  base = new char[bufsize];
36  }
37  char* p = base;
38  char* limit = base + bufsize;
39 
40  // Print the message
41  if (p < limit) {
42  va_list backup_ap;
43  va_copy(backup_ap, ap);
44  // Do not use vsnprintf elsewhere in bitcoin source code, see above.
45  p += vsnprintf(p, limit - p, format, backup_ap);
46  va_end(backup_ap);
47  }
48 
49  // Truncate to available space if necessary
50  if (p >= limit) {
51  if (iter == 0) {
52  continue; // Try again with larger buffer
53  }
54  else {
55  p = limit - 1;
56  }
57  }
58 
59  // Add newline if necessary
60  if (p == base || p[-1] != '\n') {
61  *p++ = '\n';
62  }
63 
64  assert(p <= limit);
65  base[std::min(bufsize - 1, (int)(p - base))] = '\0';
66  LogPrintf("leveldb: %s", base); /* Continued */
67  if (base != buffer) {
68  delete[] base;
69  }
70  break;
71  }
72  }
73 };
74 
75 static void SetMaxOpenFiles(leveldb::Options *options) {
76  // On most platforms the default setting of max_open_files (which is 1000)
77  // is optimal. On Windows using a large file count is OK because the handles
78  // do not interfere with select() loops. On 64-bit Unix hosts this value is
79  // also OK, because up to that amount LevelDB will use an mmap
80  // implementation that does not use extra file descriptors (the fds are
81  // closed after being mmap'ed).
82  //
83  // Increasing the value beyond the default is dangerous because LevelDB will
84  // fall back to a non-mmap implementation when the file count is too large.
85  // On 32-bit Unix host we should decrease the value because the handles use
86  // up real fds, and we want to avoid fd exhaustion issues.
87  //
88  // See PR #12495 for further discussion.
89 
90  int default_open_files = options->max_open_files;
91 #ifndef WIN32
92  if (sizeof(void*) < 8) {
93  options->max_open_files = 64;
94  }
95 #endif
96  LogPrint(BCLog::LEVELDB, "LevelDB using max_open_files=%d (default=%d)\n",
97  options->max_open_files, default_open_files);
98 }
99 
100 static leveldb::Options GetOptions(size_t nCacheSize)
101 {
102  leveldb::Options options;
103  options.block_cache = leveldb::NewLRUCache(nCacheSize / 2);
104  options.write_buffer_size = nCacheSize / 4; // up to two write buffers may be held in memory simultaneously
105  options.filter_policy = leveldb::NewBloomFilterPolicy(10);
106  options.compression = leveldb::kNoCompression;
107  options.info_log = new CBitcoinLevelDBLogger();
108  if (leveldb::kMajorVersion > 1 || (leveldb::kMajorVersion == 1 && leveldb::kMinorVersion >= 16)) {
109  // LevelDB versions before 1.16 consider short writes to be corruption. Only trigger error
110  // on corruption in later versions.
111  options.paranoid_checks = true;
112  }
113  SetMaxOpenFiles(&options);
114  return options;
115 }
116 
117 CDBWrapper::CDBWrapper(const fs::path& path, size_t nCacheSize, bool fMemory, bool fWipe, bool obfuscate)
118  : m_name{path.stem().string()}
119 {
120  penv = nullptr;
121  readoptions.verify_checksums = true;
122  iteroptions.verify_checksums = true;
123  iteroptions.fill_cache = false;
124  syncoptions.sync = true;
125  options = GetOptions(nCacheSize);
126  options.create_if_missing = true;
127  if (fMemory) {
128  penv = leveldb::NewMemEnv(leveldb::Env::Default());
129  options.env = penv;
130  } else {
131  if (fWipe) {
132  LogPrintf("Wiping LevelDB in %s\n", path.string());
133  leveldb::Status result = leveldb::DestroyDB(path.string(), options);
135  }
136  TryCreateDirectories(path);
137  LogPrintf("Opening LevelDB in %s\n", path.string());
138  }
139  leveldb::Status status = leveldb::DB::Open(options, path.string(), &pdb);
141  LogPrintf("Opened LevelDB successfully\n");
142 
143  if (gArgs.GetBoolArg("-forcecompactdb", false)) {
144  LogPrintf("Starting database compaction of %s\n", path.string());
145  pdb->CompactRange(nullptr, nullptr);
146  LogPrintf("Finished database compaction of %s\n", path.string());
147  }
148 
149  // The base-case obfuscation key, which is a noop.
150  obfuscate_key = std::vector<unsigned char>(OBFUSCATE_KEY_NUM_BYTES, '\000');
151 
152  bool key_exists = Read(OBFUSCATE_KEY_KEY, obfuscate_key);
153 
154  if (!key_exists && obfuscate && IsEmpty()) {
155  // Initialize non-degenerate obfuscation if it won't upset
156  // existing, non-obfuscated data.
157  std::vector<unsigned char> new_key = CreateObfuscateKey();
158 
159  // Write `new_key` so we don't obfuscate the key with itself
160  Write(OBFUSCATE_KEY_KEY, new_key);
161  obfuscate_key = new_key;
162 
163  LogPrintf("Wrote new obfuscate key for %s: %s\n", path.string(), HexStr(obfuscate_key));
164  }
165 
166  LogPrintf("Using obfuscation key for %s: %s\n", path.string(), HexStr(obfuscate_key));
167 }
168 
170 {
171  delete pdb;
172  pdb = nullptr;
173  delete options.filter_policy;
174  options.filter_policy = nullptr;
175  delete options.info_log;
176  options.info_log = nullptr;
177  delete options.block_cache;
178  options.block_cache = nullptr;
179  delete penv;
180  options.env = nullptr;
181 }
182 
183 bool CDBWrapper::WriteBatch(CDBBatch& batch, bool fSync)
184 {
185  const bool log_memory = LogAcceptCategory(BCLog::LEVELDB);
186  double mem_before = 0;
187  if (log_memory) {
188  mem_before = DynamicMemoryUsage() / 1024.0 / 1024;
189  }
190  leveldb::Status status = pdb->Write(fSync ? syncoptions : writeoptions, &batch.batch);
192  if (log_memory) {
193  double mem_after = DynamicMemoryUsage() / 1024.0 / 1024;
194  LogPrint(BCLog::LEVELDB, "WriteBatch memory usage: db=%s, before=%.1fMiB, after=%.1fMiB\n",
195  m_name, mem_before, mem_after);
196  }
197  return true;
198 }
199 
201  std::string memory;
202  if (!pdb->GetProperty("leveldb.approximate-memory-usage", &memory)) {
203  LogPrint(BCLog::LEVELDB, "Failed to get approximate-memory-usage property\n");
204  return 0;
205  }
206  return stoul(memory);
207 }
208 
209 // Prefixed with null character to avoid collisions with other keys
210 //
211 // We must use a string constructor which specifies length so that we copy
212 // past the null-terminator.
213 const std::string CDBWrapper::OBFUSCATE_KEY_KEY("\000obfuscate_key", 14);
214 
215 const unsigned int CDBWrapper::OBFUSCATE_KEY_NUM_BYTES = 8;
216 
221 std::vector<unsigned char> CDBWrapper::CreateObfuscateKey() const
222 {
223  unsigned char buff[OBFUSCATE_KEY_NUM_BYTES];
225  return std::vector<unsigned char>(&buff[0], &buff[OBFUSCATE_KEY_NUM_BYTES]);
226 
227 }
228 
230 {
231  std::unique_ptr<CDBIterator> it(NewIterator());
232  it->SeekToFirst();
233  return !(it->Valid());
234 }
235 
236 CDBIterator::~CDBIterator() { delete piter; }
237 bool CDBIterator::Valid() const { return piter->Valid(); }
238 void CDBIterator::SeekToFirst() { piter->SeekToFirst(); }
239 void CDBIterator::Next() { piter->Next(); }
240 
241 namespace dbwrapper_private {
242 
243 void HandleError(const leveldb::Status& status)
244 {
245  if (status.ok())
246  return;
247  const std::string errmsg = "Fatal LevelDB error: " + status.ToString();
248  LogPrintf("%s\n", errmsg);
249  LogPrintf("You can use -debug=leveldb to get more complete diagnostic messages\n");
250  throw dbwrapper_error(errmsg);
251 }
252 
253 const std::vector<unsigned char>& GetObfuscateKey(const CDBWrapper &w)
254 {
255  return w.obfuscate_key;
256 }
257 
258 } // namespace dbwrapper_private
These should be considered an implementation detail of the specific database.
Definition: dbwrapper.cpp:241
void SeekToFirst()
Definition: dbwrapper.cpp:238
Batch of changes queued to be written to a CDBWrapper.
Definition: dbwrapper.h:47
CDBWrapper(const fs::path &path, size_t nCacheSize, bool fMemory=false, bool fWipe=false, bool obfuscate=false)
Definition: dbwrapper.cpp:117
bool TryCreateDirectories(const fs::path &p)
Ignores exceptions thrown by Boost&#39;s create_directories if the requested directory exists...
Definition: system.cpp:985
static void LogPrintf(const char *fmt, const Args &... args)
Definition: logging.h:144
bool GetBoolArg(const std::string &strArg, bool fDefault) const
Return boolean argument or default value.
Definition: system.cpp:512
void HandleError(const leveldb::Status &status)
Handle database error by throwing dbwrapper_error exception.
Definition: dbwrapper.cpp:243
void GetRandBytes(unsigned char *buf, int num) noexcept
Overall design of the RNG and entropy sources.
Definition: random.cpp:659
leveldb::WriteBatch batch
Definition: dbwrapper.h:53
std::vector< unsigned char > CreateObfuscateKey() const
Returns a string (consisting of 8 random bytes) suitable for use as an obfuscating XOR key...
Definition: dbwrapper.cpp:221
CDBIterator * NewIterator()
Definition: dbwrapper.h:308
leveldb::ReadOptions readoptions
options used when reading from the database
Definition: dbwrapper.h:187
size_t DynamicMemoryUsage() const
Definition: dbwrapper.cpp:200
void Logv(const char *format, va_list ap) override
Definition: dbwrapper.cpp:21
leveldb::WriteOptions syncoptions
options used when sync writing to the database
Definition: dbwrapper.h:196
leveldb::DB * pdb
the database itself
Definition: dbwrapper.h:199
leveldb::ReadOptions iteroptions
options used when iterating over values of the database
Definition: dbwrapper.h:190
void format(std::ostream &out, const char *fmt, const Args &... args)
Format list of arguments to the stream according to given format string.
Definition: tinyformat.h:967
static void LogPrint(const BCLog::LogFlags &category, const Args &... args)
Definition: logging.h:159
leveldb::WriteOptions writeoptions
options used when writing to the database
Definition: dbwrapper.h:193
bool IsEmpty()
Return true if the database managed by this class contains no entries.
Definition: dbwrapper.cpp:229
bool Read(const K &key, V &value) const
Definition: dbwrapper.h:231
static bool LogAcceptCategory(BCLog::LogFlags category)
Return true if log accepts specified category.
Definition: logging.h:125
const std::vector< unsigned char > & GetObfuscateKey(const CDBWrapper &w)
Work around circular dependency, as well as for testing in dbwrapper_tests.
Definition: dbwrapper.cpp:253
void Next()
Definition: dbwrapper.cpp:239
static const unsigned int OBFUSCATE_KEY_NUM_BYTES
the length of the obfuscate key in number of bytes
Definition: dbwrapper.h:211
bool Write(const K &key, const V &value, bool fSync=false)
Definition: dbwrapper.h:257
std::string m_name
the name of this database
Definition: dbwrapper.h:202
leveldb::Env * penv
custom environment this database is using (may be nullptr in case of default environment) ...
Definition: dbwrapper.h:181
static const std::string OBFUSCATE_KEY_KEY
the key under which the obfuscation key is stored
Definition: dbwrapper.h:208
std::string HexStr(const T itbegin, const T itend)
Definition: strencodings.h:125
ArgsManager gArgs
Definition: system.cpp:73
static void SetMaxOpenFiles(leveldb::Options *options)
Definition: dbwrapper.cpp:75
bool Valid() const
Definition: dbwrapper.cpp:237
bool WriteBatch(CDBBatch &batch, bool fSync=false)
Definition: dbwrapper.cpp:183
static leveldb::Options GetOptions(size_t nCacheSize)
Definition: dbwrapper.cpp:100
leveldb::Options options
database options used
Definition: dbwrapper.h:184
std::vector< unsigned char > obfuscate_key
a key used for optional XOR-obfuscation of the database
Definition: dbwrapper.h:205
auto it
Definition: validation.cpp:366