#pragma once #include <functional> #include <string> #include "types.hh" class sqlite3; class sqlite3_stmt; namespace nix { /* RAII wrapper to close a SQLite database automatically. */ struct SQLite { sqlite3 * db = 0; SQLite() { } SQLite(const Path & path); SQLite(const SQLite & from) = delete; SQLite& operator = (const SQLite & from) = delete; SQLite& operator = (SQLite && from) { db = from.db; from.db = 0; return *this; } ~SQLite(); operator sqlite3 * () { return db; } void exec(const std::string & stmt); }; /* RAII wrapper to create and destroy SQLite prepared statements. */ struct SQLiteStmt { sqlite3 * db = 0; sqlite3_stmt * stmt = 0; std::string sql; SQLiteStmt() { } SQLiteStmt(sqlite3 * db, const std::string & sql) { create(db, sql); } void create(sqlite3 * db, const std::string & s); ~SQLiteStmt(); operator sqlite3_stmt * () { return stmt; } /* Helper for binding / executing statements. */ class Use { friend struct SQLiteStmt; private: SQLiteStmt & stmt; unsigned int curArg = 1; Use(SQLiteStmt & stmt); public: ~Use(); /* Bind the next parameter. */ Use & operator () (const std::string & value, bool notNull = true); Use & operator () (int64_t value, bool notNull = true); Use & bind(); // null int step(); /* Execute a statement that does not return rows. */ void exec(); /* For statements that return 0 or more rows. Returns true iff a row is available. */ bool next(); std::string getStr(int col); int64_t getInt(int col); bool isNull(int col); }; Use use() { return Use(*this); } }; /* RAII helper that ensures transactions are aborted unless explicitly committed. */ struct SQLiteTxn { bool active = false; sqlite3 * db; SQLiteTxn(sqlite3 * db); void commit(); ~SQLiteTxn(); }; MakeError(SQLiteError, Error); MakeError(SQLiteBusy, SQLiteError); [[noreturn]] void throwSQLiteError(sqlite3 * db, const format & f); void handleSQLiteBusy(const SQLiteBusy & e); /* Convenience function for retrying a SQLite transaction when the database is busy. */ template<typename T> T retrySQLite(std::function<T()> fun) { while (true) { try { return fun(); } catch (SQLiteBusy & e) { handleSQLiteBusy(e); } } } }