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#pragma once
///@file
#include <chrono>
#include <kj/async.h>
#include <string>
#include <type_traits>
#include "lix/libutil/async.hh"
#include "lix/libutil/result.hh"
#include "lix/libutil/types.hh"
#include "lix/libutil/error.hh"
struct sqlite3;
struct sqlite3_stmt;
namespace nix {
enum class SQLiteOpenMode {
/**
* Open the database in read-write mode.
* If the database does not exist, it will be created.
*/
Normal,
/**
* Open the database in read-write mode.
* Fails with an error if the database does not exist.
*/
NoCreate,
/**
* Open the database in immutable mode.
* In addition to the database being read-only,
* no wal or journal files will be created by sqlite.
* Use this mode if the database is on a read-only filesystem.
* Fails with an error if the database does not exist.
*/
Immutable,
};
enum class SQLiteTxnType {
/**
* A deferred transaction does not actually begin until the database is first accessed.
* If the first statement in the transaction is a SELECT then a read transaction is started.
* Subsequent write statements will upgrade the transaction to a write transaction if possible,
* or return SQLITE_BUSY if another write transaction started on another database connection.
* If the first statement in the transaction is a write statement then a write transaction
* is started.
*/
Deferred,
/**
* An immediate transaction causes the database to start a write transaction immediately,
* without waiting for a write statement. The transaction might fail wth SQLITE_BUSY if another
* write transaction is already active on another database connection.
*/
Immediate,
/**
* An exclusive transaction causes the database to start a write transaction immediately.
* In WAL mode this is the same as Immediate, but in other journaling modes this prevents
* other database connections from reading the database while a transction is underway.
*/
Exclusive,
};
struct SQLiteError;
class SQLiteStmt;
class SQLiteTxn;
/**
* RAII wrapper to close a SQLite database automatically.
*/
class SQLite
{
friend SQLiteError;
struct Close {
void operator()(sqlite3 * db);
};
std::unique_ptr<sqlite3, Close> db;
public:
SQLite() = default;
SQLite(const Path & path, SQLiteOpenMode mode = SQLiteOpenMode::Normal);
/**
* Disable synchronous mode, set truncate journal mode.
*/
void isCache();
void exec(const std::string & stmt, NeverAsync = {});
SQLiteStmt create(const std::string & stmt);
SQLiteTxn beginTransaction(SQLiteTxnType type = SQLiteTxnType::Deferred);
void setPersistWAL(bool persist);
uint64_t getLastInsertedRowId();
uint64_t getRowsChanged();
};
/**
* RAII wrapper to create and destroy SQLite prepared statements.
*/
class SQLiteStmt
{
friend SQLite;
struct Finalize {
SQLiteStmt * parent;
void operator()(sqlite3_stmt * stmt);
};
sqlite3 * db = 0;
std::unique_ptr<sqlite3_stmt, Finalize> stmt;
std::string sql;
SQLiteStmt(sqlite3 * db, const std::string & sql);
public:
SQLiteStmt() = default;
/**
* Helper for binding / executing statements.
*/
class Use
{
friend class SQLiteStmt;
private:
SQLiteStmt & stmt;
unsigned int curArg = 1;
Use(SQLiteStmt & stmt);
public:
~Use();
/**
* Bind the next parameter.
*/
Use & operator () (std::string_view value, bool notNull = true);
Use & operator () (const unsigned char * data, size_t len, bool notNull = true);
Use & operator () (int64_t value, bool notNull = true);
Use & bind(); // null
/**
* 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);
std::optional<std::string> getStrNullable(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.
*/
class SQLiteTxn
{
friend SQLite;
struct Rollback {
void operator()(sqlite3 * db);
};
std::unique_ptr<sqlite3, Rollback> db;
explicit SQLiteTxn(sqlite3 * db, SQLiteTxnType type);
public:
void commit();
};
struct SQLiteError : Error
{
friend SQLite;
friend SQLiteStmt;
friend SQLiteTxn;
std::string path;
std::string errMsg;
int errNo, extendedErrNo, offset;
SQLiteError(const char *path, const char *errMsg, int errNo, int extendedErrNo, int offset, HintFmt && hf);
protected:
template<typename... Args>
SQLiteError(const char *path, const char *errMsg, int errNo, int extendedErrNo, int offset, const std::string & fs, const Args & ... args)
: SQLiteError(path, errMsg, errNo, extendedErrNo, offset, HintFmt(fs, args...))
{ }
template<typename... Args>
[[noreturn]] static void throw_(sqlite3 * db, const std::string & fs, const Args & ... args) {
throw_(db, HintFmt(fs, args...));
}
[[noreturn]] static void throw_(sqlite3 * db, HintFmt && hf);
};
MakeError(SQLiteBusy, SQLiteError);
void handleSQLiteBusy(const SQLiteBusy & e, std::chrono::time_point<std::chrono::steady_clock> & nextWarning);
kj::Promise<Result<void>> handleSQLiteBusyAsync(const SQLiteBusy & e, std::chrono::time_point<std::chrono::steady_clock> & nextWarning);
/**
* Convenience function for retrying a SQLite transaction when the
* database is busy.
*/
template<typename F>
requires(!requires(F f) { []<typename T>(kj::Promise<T>) {}(f()); })
auto retrySQLite(F fun, NeverAsync = {})
{
auto nextWarning = std::chrono::steady_clock::now() + std::chrono::seconds(1);
while (true) {
try {
return fun();
} catch (SQLiteBusy & e) {
handleSQLiteBusy(e, nextWarning);
}
}
}
template<typename F>
requires requires(F f) { []<typename T>(kj::Promise<Result<T>>) {}(f()); }
auto retrySQLite(F fun)
{
return [](F fun) -> decltype(fun()) {
auto nextWarning = std::chrono::steady_clock::now() + std::chrono::seconds(1);
while (true) {
kj::Promise<Result<void>> handleBusy{nullptr};
try {
if constexpr (std::is_same_v<decltype(fun()), kj::Promise<Result<void>>>) {
LIX_TRY_AWAIT(fun());
co_return result::success();
} else {
co_return LIX_TRY_AWAIT(fun());
}
} catch (SQLiteBusy & e) {
handleBusy = handleSQLiteBusyAsync(e, nextWarning);
} catch (...) {
co_return result::current_exception();
}
LIX_TRY_AWAIT(handleBusy);
}
}(std::move(fun));
}
}
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