fediglam/src/sql/lib.zig

660 lines
23 KiB
Zig

const std = @import("std");
const util = @import("util");
const build_options = @import("build_options");
const postgres = if (build_options.enable_postgres)
@import("./engines/postgres.zig")
else
@import("./engines/null.zig");
const sqlite = if (build_options.enable_sqlite)
@import("./engines/sqlite.zig")
else
@import("./engines/null.zig");
const common = @import("./engines/common.zig");
const Allocator = std.mem.Allocator;
const errors = @import("./errors.zig").library_errors;
pub const AcquireError = OpenError || error{NoConnectionsLeft};
pub const OpenError = errors.OpenError;
pub const QueryError = errors.QueryError;
pub const RowError = errors.RowError;
pub const QueryRowError = errors.QueryRowError;
pub const BeginError = errors.BeginError;
pub const CommitError = errors.CommitError;
pub const QueryOptions = common.QueryOptions;
pub const Engine = enum {
postgres,
sqlite,
};
/// Helper for building queries at runtime. All constituent parts of the
/// query should be defined at comptime, however the choice of whether
/// or not to include them can occur at runtime.
pub const QueryBuilder = struct {
array: std.ArrayList(u8),
where_clauses_appended: usize = 0,
pub fn init(alloc: std.mem.Allocator) QueryBuilder {
return QueryBuilder{ .array = std.ArrayList(u8).init(alloc) };
}
pub fn deinit(self: *const QueryBuilder) void {
self.array.deinit();
}
/// Add a chunk of sql to the query without processing
pub fn appendSlice(self: *QueryBuilder, comptime sql: []const u8) !void {
try self.array.appendSlice(sql);
}
/// Add a where clause to the query. Clauses are assumed to be components
/// in an overall expression in Conjunctive Normal Form (AND of OR's).
/// https://en.wikipedia.org/wiki/Conjunctive_normal_form
/// All calls to andWhere must be contiguous, that is, they cannot be
/// interspersed with calls to appendSlice
pub fn andWhere(self: *QueryBuilder, comptime clause: []const u8) !void {
if (self.where_clauses_appended == 0) {
try self.array.appendSlice("WHERE ");
} else {
try self.array.appendSlice(" AND ");
}
try self.array.appendSlice(clause);
self.where_clauses_appended += 1;
}
pub fn str(self: *const QueryBuilder) []const u8 {
return self.array.items;
}
pub fn terminate(self: *QueryBuilder) ![:0]const u8 {
std.debug.assert(self.array.items.len != 0);
if (self.array.items[self.array.items.len - 1] != 0) try self.array.append(0);
return std.meta.assumeSentinel(self.array.items, 0);
}
};
// TODO: make this suck less
pub const Config = union(Engine) {
postgres: struct {
pg_conn_str: [:0]const u8,
},
sqlite: struct {
sqlite_file_path: [:0]const u8,
sqlite_is_uri: bool = false,
},
};
const RawResults = union(Engine) {
postgres: postgres.Results,
sqlite: sqlite.Results,
fn finish(self: RawResults) void {
switch (self) {
.postgres => |pg| pg.finish(),
.sqlite => |lite| lite.finish(),
}
}
fn columnCount(self: RawResults) !u15 {
return try switch (self) {
.postgres => |pg| pg.columnCount(),
.sqlite => |lite| lite.columnCount(),
};
}
fn columnIndex(self: RawResults, name: []const u8) error{ NotFound, Unexpected }!u15 {
return switch (self) {
.postgres => |pg| pg.columnIndex(name),
.sqlite => |lite| lite.columnIndex(name),
} catch |err| switch (err) {
error.OutOfRange => error.Unexpected,
error.NotFound => error.NotFound,
};
}
fn row(self: *RawResults) RowError!?Row {
return switch (self.*) {
.postgres => |*pg| if (try pg.row()) |r| Row{ .postgres = r } else null,
.sqlite => |*lite| if (try lite.row()) |r| Row{ .sqlite = r } else null,
};
}
};
fn FieldPtr(comptime Ptr: type, comptime names: []const []const u8) type {
if (names.len == 0) return Ptr;
const T = std.meta.Child(Ptr);
const field = for (@typeInfo(T).Struct.fields) |f| {
if (std.mem.eql(u8, f.name, names[0])) break f;
} else @compileError("Unknown field " ++ names[0] ++ " in type " ++ @typeName(T));
return FieldPtr(*field.field_type, names[1..]);
}
fn fieldPtr(ptr: anytype, comptime names: []const []const u8) FieldPtr(@TypeOf(ptr), names) {
if (names.len == 0) return ptr;
return fieldPtr(&@field(ptr.*, names[0]), names[1..]);
}
fn isScalar(comptime T: type) bool {
if (comptime std.meta.trait.isZigString(T)) return true;
if (comptime std.meta.trait.isIntegral(T)) return true;
if (comptime std.meta.trait.isFloat(T)) return true;
if (comptime std.meta.trait.is(.Enum)(T)) return true;
if (T == bool) return true;
if (comptime std.meta.trait.hasFn("parse")(T)) return true;
if (comptime std.meta.trait.is(.Optional)(T) and isScalar(std.meta.Child(T))) return true;
return false;
}
fn recursiveFieldPaths(comptime T: type, comptime prefix: []const []const u8) []const []const []const u8 {
comptime {
var fields: []const []const []const u8 = &.{};
for (std.meta.fields(T)) |f| {
const full_name = prefix ++ [_][]const u8{f.name};
if (isScalar(f.field_type)) {
fields = fields ++ [_][]const []const u8{full_name};
} else {
fields = fields ++ recursiveFieldPaths(f.field_type, full_name);
}
}
return fields;
}
}
// Represents a set of results.
// row() must be called until it returns null, or the query may not complete
// Must be deallocated by a call to finish()
pub fn Results(comptime T: type) type {
// would normally make this a declaration of the struct, but it causes the compiler to crash
const fields = if (T == void) .{} else recursiveFieldPaths(T, &.{});
return struct {
const Self = @This();
underlying: RawResults,
column_indices: [fields.len]u15,
fn from(underlying: RawResults) QueryError!Self {
if (std.debug.runtime_safety and fields.len != underlying.columnCount() catch unreachable) {
std.log.err("Expected {} columns in result, got {}", .{ fields.len, underlying.columnCount() catch unreachable });
return error.ColumnMismatch;
}
return Self{ .underlying = underlying, .column_indices = blk: {
var indices: [fields.len]u15 = undefined;
inline for (fields) |f, i| {
if (comptime std.meta.trait.isTuple(T)) {
indices[i] = i;
} else {
const name = util.comptimeJoin(".", f);
indices[i] =
underlying.columnIndex(name) catch {
std.log.err("Could not find column index for field {s}", .{name});
return error.ColumnMismatch;
};
}
}
break :blk indices;
} };
}
pub fn finish(self: Self) void {
self.underlying.finish();
}
// Returns the next row of results, or null if there are no more rows.
// Caller owns all memory allocated. The entire object can be deallocated with a
// call to util.deepFree
pub fn row(self: *Self, alloc: ?Allocator) RowError!?T {
if (try self.underlying.row()) |row_val| {
var result: T = undefined;
var fields_allocated: usize = 0;
errdefer inline for (fields) |f, i| {
// Iteration bounds must be defined at comptime (inline for) but the number of fields we could
// successfully allocate is defined at runtime. So we iterate over the entire field array and
// conditionally deallocate fields in the loop.
const ptr = fieldPtr(&result, f);
if (i < fields_allocated) util.deepFree(alloc, ptr.*);
};
inline for (fields) |f, i| {
// TODO: Causes compiler segfault. why?
//const F = f.field_type;
//const F = @TypeOf(@field(result, f.name));
const F = std.meta.Child(FieldPtr(*@TypeOf(result), f));
const ptr = fieldPtr(&result, f);
const name = util.comptimeJoin(".", f);
ptr.* = row_val.get(F, self.column_indices[i], alloc) catch |err| {
std.log.err("SQL: Error getting column {s} of type {}", .{ name, F });
return err;
};
fields_allocated += 1;
}
return result;
} else return null;
}
};
}
// Row is invalidated by the next call to result.row()
const Row = union(Engine) {
postgres: postgres.Row,
sqlite: sqlite.Row,
// Returns a value of type T from the zero-indexed column given by idx.
// Not all types require an allocator to be present. If an allocator is needed but
// not required, it will return error.AllocatorRequired.
// The caller is responsible for deallocating T, if relevant.
fn get(self: Row, comptime T: type, idx: u15, alloc: ?Allocator) common.GetError!T {
if (T == void) return;
return switch (self) {
.postgres => |pg| pg.get(T, idx, alloc),
.sqlite => |lite| lite.get(T, idx, alloc),
};
}
};
pub const ConstraintMode = enum {
deferred,
immediate,
};
pub const ConnPool = struct {
const max_conns = 4;
const Conn = struct {
engine: union(Engine) {
postgres: postgres.Db,
sqlite: sqlite.Db,
},
in_use: std.atomic.Atomic(bool) = std.atomic.Atomic(bool).init(false),
current_tx_level: u8 = 0,
};
config: Config,
connections: [max_conns]Conn,
pub fn init(cfg: Config) OpenError!ConnPool {
var self = ConnPool{
.config = cfg,
.connections = undefined,
};
var count: usize = 0;
errdefer for (self.connections[0..count]) |*c| closeConn(c);
for (self.connections) |*c| {
c.* = try self.createConn();
count += 1;
}
return self;
}
pub fn deinit(self: *ConnPool) void {
for (self.connections) |*c| closeConn(c);
}
pub fn acquire(self: *ConnPool) AcquireError!Db {
for (self.connections) |*c| {
if (tryAcquire(c)) return Db{ .conn = c };
}
return error.NoConnectionsLeft;
}
fn tryAcquire(conn: *Conn) bool {
const acquired = !conn.in_use.swap(true, .AcqRel);
if (acquired) {
if (conn.current_tx_level != 0) @panic("Transaction still open on unused db connection");
return true;
}
return false;
}
fn createConn(self: *ConnPool) OpenError!Conn {
return switch (self.config) {
.postgres => |postgres_cfg| Conn{
.engine = .{
.postgres = try postgres.Db.open(postgres_cfg.pg_conn_str),
},
},
.sqlite => |lite_cfg| Conn{
.engine = .{
.sqlite = if (lite_cfg.sqlite_is_uri)
try sqlite.Db.openUri(lite_cfg.sqlite_file_path)
else
try sqlite.Db.open(lite_cfg.sqlite_file_path),
},
},
};
}
fn closeConn(conn: *Conn) void {
if (conn.in_use.loadUnchecked()) @panic("DB Conn still open");
switch (conn.engine) {
.postgres => |pg| pg.close(),
.sqlite => |lite| lite.close(),
}
}
};
pub const Db = Tx(0);
/// When tx_level == 0, the DB is operating in "implied transaction" mode where
/// every command is its own transaction
/// When tx_level >= 1, the DB has an explicit transaction open
/// When tx_level >= 2, the DB has (tx_level - 1) levels of transaction savepoints open
/// (like nested transactions)
fn Tx(comptime tx_level: u8) type {
return struct {
const Self = @This();
const savepoint_name = if (tx_level == 0)
@compileError("Transaction not started")
else
std.fmt.comptimePrint("save_{}", .{tx_level});
const next_savepoint_name = Tx(tx_level + 1).savepoint_name;
conn: *ConnPool.Conn,
/// The type of SQL engine being used. Use of this function should be discouraged
pub fn sqlEngine(self: Self) Engine {
return self.conn.engine;
}
/// Return the connection to the pool
pub fn releaseConnection(self: Self) void {
if (tx_level != 0) @compileError("close must be called on root db");
if (self.conn.current_tx_level != 0) {
std.log.warn("Database released while transaction in progress!", .{});
self.rollbackUnchecked() catch {};
}
if (!self.conn.in_use.swap(false, .AcqRel)) @panic("Double close on db conection");
}
// ********* Transaction management functions **********
/// Start an explicit transaction
pub fn begin(self: Self) !Tx(1) {
if (tx_level != 0) @compileError("Transaction already started");
if (self.conn.current_tx_level != 0) return error.BadTransactionState;
try self.exec("BEGIN", {}, null);
self.conn.current_tx_level = 1;
return Tx(1){ .conn = self.conn };
}
/// Create a savepoint (nested transaction)
pub fn savepoint(self: Self) !Tx(tx_level + 1) {
if (tx_level == 0) @compileError("Cannot place a savepoint on an implicit transaction");
if (self.conn.current_tx_level != tx_level) return error.BadTransactionState;
try self.exec("SAVEPOINT " ++ next_savepoint_name, {}, null);
self.conn.current_tx_level = tx_level + 1;
return Tx(tx_level + 1){ .conn = self.conn };
}
/// Commit the entire transaction
pub fn commit(self: Self) !void {
if (tx_level == 0) @compileError("Transaction not started");
if (tx_level >= 2) @compileError("Cannot commit a savepoint");
if (self.conn.current_tx_level == 0) return error.BadTransactionState;
try self.exec("COMMIT", {}, null);
self.conn.current_tx_level = 0;
}
/// Release the current savepoint and all savepoints created from it.
pub fn release(self: Self) !void {
if (tx_level == 0) @compileError("Transaction not started");
if (tx_level == 1) @compileError("Cannot release a transaction");
if (self.conn.current_tx_level < tx_level) return error.BadTransactionState;
try self.exec("RELEASE SAVEPOINT " ++ savepoint_name, {}, null);
self.conn.current_tx_level = tx_level - 1;
}
/// Rolls back the entire transaction
pub fn rollbackTx(self: Self) !void {
if (tx_level == 0) @compileError("Transaction not started");
if (tx_level >= 2) @compileError("Cannot rollback a transaction using a savepoint");
if (self.conn.current_tx_level == 0) return error.BadTransactionState;
try self.rollbackUnchecked();
self.conn.current_tx_level = 0;
}
/// Attempts to roll back to a savepoint
pub fn rollbackSavepoint(self: Self) !void {
if (tx_level == 0) @compileError("Transaction not started");
if (tx_level == 1) @compileError("Cannot rollback a savepoint on the entire transaction");
if (self.conn.current_tx_level < tx_level) return error.BadTransactionState;
try self.exec("ROLLBACK TO " ++ savepoint_name, {}, null);
self.conn.current_tx_level = tx_level - 1;
}
/// Perform whichever rollback is appropriate for the situation
pub fn rollback(self: Self) void {
(if (tx_level < 2) self.rollbackTx() else self.rollbackSavepoint()) catch |err| {
std.log.err("Failed to rollback transaction: {}", .{err});
@panic("TODO: more gracefully handle rollback failures");
};
}
pub const beginOrSavepoint = if (tx_level == 0) begin else savepoint;
pub const commitOrRelease = if (tx_level < 2) commit else release;
// Allows relaxing *some* constraints for the lifetime of the transaction.
// You should generally not do this, but it's useful when bootstrapping
// the initial admin community and cluster operator user.
pub fn setConstraintMode(self: Self, mode: ConstraintMode) !void {
if (tx_level == 0) @compileError("Transaction not started");
if (tx_level >= 2) @compileError("Cannot set constraint mode on a savepoint");
switch (self.sqlEngine()) {
.sqlite => try self.exec(
switch (mode) {
.immediate => "PRAGMA defer_foreign_keys = FALSE",
.deferred => "PRAGMA defer_foreign_keys = TRUE",
},
{},
null,
),
.postgres => try self.exec(
switch (mode) {
.immediate => "SET CONSTRAINTS ALL IMMEDIATE",
.deferred => "SET CONSTRAINTS ALL DEFERRED",
},
{},
null,
),
}
}
// ********** Query Helpers ************
/// Runs a command without returning results
pub fn exec(
self: Self,
sql: [:0]const u8,
args: anytype,
alloc: ?std.mem.Allocator,
) !void {
try self.execInternal(sql, args, alloc, true);
}
pub fn queryWithOptions(
self: Self,
comptime RowType: type,
sql: [:0]const u8,
args: anytype,
options: QueryOptions,
) QueryError!Results(RowType) {
return Results(RowType).from(try self.runSql(sql, args, options, true));
}
pub fn query(
self: Self,
comptime RowType: type,
sql: [:0]const u8,
args: anytype,
alloc: ?Allocator,
) QueryError!Results(RowType) {
return self.queryWithOptions(RowType, sql, args, .{ .allocator = alloc });
}
/// Runs a query to completion and returns a row of results, unless the query
/// returned a different number of rows.
pub fn queryRow(
self: Self,
comptime RowType: type,
q: [:0]const u8,
args: anytype,
alloc: ?Allocator,
) QueryRowError!RowType {
var results = try self.query(RowType, q, args, alloc);
defer results.finish();
const row = (try results.row(alloc)) orelse return error.NoRows;
errdefer util.deepFree(alloc, row);
// execute query to completion
var more_rows = false;
while (try results.row(alloc)) |r| {
util.deepFree(alloc, r);
more_rows = true;
}
if (more_rows) return error.TooManyRows;
return row;
}
// Runs a query to completion and returns the results as a slice
pub fn queryRowsWithOptions(
self: Self,
comptime RowType: type,
q: [:0]const u8,
args: anytype,
max_items: ?usize,
options: QueryOptions,
) QueryRowError![]RowType {
var results = try self.queryWithOptions(RowType, q, args, options);
defer results.finish();
const alloc = options.allocator orelse return error.AllocatorRequired;
var result_array = std.ArrayList(RowType).init(alloc);
errdefer result_array.deinit();
if (max_items) |max| try result_array.ensureTotalCapacity(max);
errdefer for (result_array.items) |r| util.deepFree(alloc, r);
var too_many: bool = false;
while (try results.row(alloc)) |row| {
errdefer util.deepFree(alloc, row);
if (max_items) |max| {
if (result_array.items.len >= max) {
util.deepFree(alloc, row);
too_many = true;
continue;
}
}
try result_array.append(row);
}
if (too_many) return error.TooManyRows;
return result_array.toOwnedSlice();
}
// Inserts a single value into a table
pub fn insert(
self: Self,
comptime table: []const u8,
value: anytype,
alloc: ?std.mem.Allocator,
) !void {
const ValueType = comptime @TypeOf(value);
const fields = std.meta.fields(ValueType);
comptime var types: [fields.len]type = undefined;
comptime var table_spec: []const u8 = table ++ "(";
comptime var value_spec: []const u8 = "(";
inline for (fields) |field, i| {
// This causes a compiler crash. Why?
//const F = field.field_type;
const F = @TypeOf(@field(value, field.name));
// causes issues if F is @TypeOf(null), use dummy type
types[i] = if (F == @TypeOf(null)) ?i64 else F;
table_spec = comptime (table_spec ++ field.name ++ ",");
value_spec = comptime value_spec ++ std.fmt.comptimePrint("${},", .{i + 1});
}
table_spec = comptime table_spec[0 .. table_spec.len - 1] ++ ")";
value_spec = comptime value_spec[0 .. value_spec.len - 1] ++ ")";
const q = comptime std.fmt.comptimePrint(
"INSERT INTO {s} VALUES {s}",
.{ table_spec, value_spec },
);
var args_tuple: std.meta.Tuple(&types) = undefined;
inline for (fields) |field, i| {
args_tuple[i] = @field(value, field.name);
}
try self.exec(q, args_tuple, alloc);
}
// internal helpers
fn runSql(
self: Self,
sql: [:0]const u8,
args: anytype,
opt: QueryOptions,
comptime check_tx: bool,
) !RawResults {
if (check_tx and self.conn.current_tx_level != tx_level) return error.BadTransactionState;
return switch (self.conn.engine) {
.postgres => |pg| RawResults{ .postgres = try pg.exec(sql, args, opt) },
.sqlite => |lite| RawResults{ .sqlite = try lite.exec(sql, args, opt) },
};
}
fn execInternal(
self: Self,
sql: [:0]const u8,
args: anytype,
alloc: ?std.mem.Allocator,
comptime check_tx: bool,
) !void {
var results = try self.runSql(sql, args, .{ .allocator = alloc }, check_tx);
defer results.finish();
while (try results.row()) |_| {}
}
fn rollbackUnchecked(self: Self) !void {
try self.exec("ROLLBACK", {}, null);
}
};
}