Line data Source code
1 : // Copyright (c) 2020-2021 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 : #ifndef BITCOIN_WALLET_SQLITE_H
6 : #define BITCOIN_WALLET_SQLITE_H
7 :
8 : #include <sync.h>
9 : #include <wallet/db.h>
10 :
11 : struct bilingual_str;
12 :
13 : struct sqlite3_stmt;
14 : struct sqlite3;
15 :
16 : namespace wallet {
17 : class SQLiteDatabase;
18 :
19 : /** RAII class that provides a database cursor */
20 : class SQLiteCursor : public DatabaseCursor
21 : {
22 : public:
23 : sqlite3_stmt* m_cursor_stmt{nullptr};
24 : // Copies of the prefix things for the prefix cursor.
25 : // Prevents SQLite from accessing temp variables for the prefix things.
26 : std::vector<std::byte> m_prefix_range_start;
27 : std::vector<std::byte> m_prefix_range_end;
28 :
29 0 : explicit SQLiteCursor() = default;
30 0 : explicit SQLiteCursor(std::vector<std::byte> start_range, std::vector<std::byte> end_range)
31 0 : : m_prefix_range_start(std::move(start_range)),
32 0 : m_prefix_range_end(std::move(end_range))
33 0 : {}
34 : ~SQLiteCursor() override;
35 :
36 : Status Next(DataStream& key, DataStream& value) override;
37 : };
38 :
39 : /** Class responsible for executing SQL statements in SQLite databases.
40 : * Methods are virtual so they can be overridden by unit tests testing unusual database conditions. */
41 0 : class SQliteExecHandler
42 : {
43 : public:
44 0 : virtual ~SQliteExecHandler() = default;
45 : virtual int Exec(SQLiteDatabase& database, const std::string& statement);
46 : };
47 :
48 : /** RAII class that provides access to a WalletDatabase */
49 : class SQLiteBatch : public DatabaseBatch
50 : {
51 : private:
52 : SQLiteDatabase& m_database;
53 : std::unique_ptr<SQliteExecHandler> m_exec_handler{std::make_unique<SQliteExecHandler>()};
54 :
55 : sqlite3_stmt* m_read_stmt{nullptr};
56 : sqlite3_stmt* m_insert_stmt{nullptr};
57 : sqlite3_stmt* m_overwrite_stmt{nullptr};
58 : sqlite3_stmt* m_delete_stmt{nullptr};
59 : sqlite3_stmt* m_delete_prefix_stmt{nullptr};
60 :
61 : /** Whether this batch has started a database transaction and whether it owns SQLiteDatabase::m_write_semaphore.
62 : * If the batch starts a db tx, it acquires the semaphore and sets this to true, keeping the semaphore
63 : * until the transaction ends to prevent other batch objects from writing to the database.
64 : *
65 : * If this batch did not start a transaction, the semaphore is acquired transiently when writing and m_txn
66 : * is not set.
67 : *
68 : * m_txn is different from HasActiveTxn() as it is only true when this batch has started the transaction,
69 : * not just when any batch has started a transaction.
70 : */
71 : bool m_txn{false};
72 :
73 : void SetupSQLStatements();
74 : bool ExecStatement(sqlite3_stmt* stmt, Span<const std::byte> blob);
75 :
76 : bool ReadKey(DataStream&& key, DataStream& value) override;
77 : bool WriteKey(DataStream&& key, DataStream&& value, bool overwrite = true) override;
78 : bool EraseKey(DataStream&& key) override;
79 : bool HasKey(DataStream&& key) override;
80 : bool ErasePrefix(Span<const std::byte> prefix) override;
81 :
82 : public:
83 : explicit SQLiteBatch(SQLiteDatabase& database);
84 0 : ~SQLiteBatch() override { Close(); }
85 :
86 : void SetExecHandler(std::unique_ptr<SQliteExecHandler>&& handler) { m_exec_handler = std::move(handler); }
87 :
88 : /* No-op. See comment on SQLiteDatabase::Flush */
89 0 : void Flush() override {}
90 :
91 : void Close() override;
92 :
93 : std::unique_ptr<DatabaseCursor> GetNewCursor() override;
94 : std::unique_ptr<DatabaseCursor> GetNewPrefixCursor(Span<const std::byte> prefix) override;
95 : bool TxnBegin() override;
96 : bool TxnCommit() override;
97 : bool TxnAbort() override;
98 0 : bool HasActiveTxn() override { return m_txn; }
99 : };
100 :
101 : /** An instance of this class represents one SQLite3 database.
102 : **/
103 : class SQLiteDatabase : public WalletDatabase
104 : {
105 : private:
106 : const bool m_mock{false};
107 :
108 : const std::string m_dir_path;
109 :
110 : const std::string m_file_path;
111 :
112 : /**
113 : * This mutex protects SQLite initialization and shutdown.
114 : * sqlite3_config() and sqlite3_shutdown() are not thread-safe (sqlite3_initialize() is).
115 : * Concurrent threads that execute SQLiteDatabase::SQLiteDatabase() should have just one
116 : * of them do the init and the rest wait for it to complete before all can proceed.
117 : */
118 : static Mutex g_sqlite_mutex;
119 : static int g_sqlite_count GUARDED_BY(g_sqlite_mutex);
120 :
121 : void Cleanup() noexcept EXCLUSIVE_LOCKS_REQUIRED(!g_sqlite_mutex);
122 :
123 : public:
124 : SQLiteDatabase() = delete;
125 :
126 : /** Create DB handle to real database */
127 : SQLiteDatabase(const fs::path& dir_path, const fs::path& file_path, const DatabaseOptions& options, bool mock = false);
128 :
129 : ~SQLiteDatabase();
130 :
131 : // Batches must acquire this semaphore on writing, and release when done writing.
132 : // This ensures that only one batch is modifying the database at a time.
133 : CSemaphore m_write_semaphore;
134 :
135 : bool Verify(bilingual_str& error);
136 :
137 : /** Open the database if it is not already opened */
138 : void Open() override;
139 :
140 : /** Close the database */
141 : void Close() override;
142 :
143 : /* These functions are unused */
144 0 : void AddRef() override { assert(false); }
145 0 : void RemoveRef() override { assert(false); }
146 :
147 : /** Rewrite the entire database on disk */
148 : bool Rewrite(const char* skip = nullptr) override;
149 :
150 : /** Back up the entire database to a file.
151 : */
152 : bool Backup(const std::string& dest) const override;
153 :
154 : /** No-ops
155 : *
156 : * SQLite always flushes everything to the database file after each transaction
157 : * (each Read/Write/Erase that we do is its own transaction unless we called
158 : * TxnBegin) so there is no need to have Flush or Periodic Flush.
159 : *
160 : * There is no DB env to reload, so ReloadDbEnv has nothing to do
161 : */
162 0 : void Flush() override {}
163 0 : bool PeriodicFlush() override { return false; }
164 0 : void ReloadDbEnv() override {}
165 :
166 0 : void IncrementUpdateCounter() override { ++nUpdateCounter; }
167 :
168 0 : std::string Filename() override { return m_file_path; }
169 0 : std::string Format() override { return "sqlite"; }
170 :
171 : /** Make a SQLiteBatch connected to this database */
172 : std::unique_ptr<DatabaseBatch> MakeBatch(bool flush_on_close = true) override;
173 :
174 : /** Return true if there is an on-going txn in this connection */
175 : bool HasActiveTxn();
176 :
177 : sqlite3* m_db{nullptr};
178 : bool m_use_unsafe_sync;
179 : };
180 :
181 : std::unique_ptr<SQLiteDatabase> MakeSQLiteDatabase(const fs::path& path, const DatabaseOptions& options, DatabaseStatus& status, bilingual_str& error);
182 :
183 : std::string SQLiteDatabaseVersion();
184 : } // namespace wallet
185 :
186 : #endif // BITCOIN_WALLET_SQLITE_H
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