tiny.sql.OverflowPage

1pub const Overflow = struct {2    bytes: *[size]u8,34    pub fn init(bytes: *[size]u8, page_id: u64, next_page: u32, fragment: []const u8) Error!Overflow {5        if (fragment.len == 0 or fragment.len > overflow_capacity) return error.ValueTooLarge;6        if (next_page != 0 and @as(u64, next_page) == page_id) return error.InvalidPageId;7        var overflow = Overflow{ .bytes = bytes };8        @memset(overflow.bytes, 0);9        @memcpy(overflow.bytes[magic_offset..][0..magic.len], magic[0..]);10        overflow.bytes[version_offset] = format_version;11        overflow.bytes[kind_offset] = overflow_kind;12        overflow.writeU16(flags_offset, 0);13        overflow.writeU64(id_offset, page_id);14        overflow.writeU64(generation_offset, 0);15        overflow.writeU32(overflow_next_offset, next_page);16        overflow.writeU16(overflow_used_offset, @intCast(fragment.len));17        overflow.writeU16(overflow_reserved_offset, 0);18        @memcpy(overflow.bytes[header_size..][0..fragment.len], fragment);19        return overflow;20    }2122    pub fn load(bytes: *[size]u8) Error!Overflow {23        const overflow = Overflow{ .bytes = bytes };24        try overflow.validate();25        return overflow;26    }2728    pub fn id(self: *const Overflow) u64 {29        return self.readU64(id_offset);30    }3132    pub fn next(self: *const Overflow) u32 {33        return self.readU32(overflow_next_offset);34    }3536    pub fn used(self: *const Overflow) usize {37        return self.readU16(overflow_used_offset);38    }3940    pub fn content(self: *const Overflow) []const u8 {41        return self.bytes[header_size..][0..self.used()];42    }4344    fn validate(self: *const Overflow) Error!void {45        if (!std.mem.eql(u8, self.bytes[magic_offset..][0..magic.len], magic[0..])) return error.InvalidPage;46        if (self.bytes[version_offset] != format_version) return error.InvalidPage;47        if (self.bytes[kind_offset] != overflow_kind) return error.InvalidPage;48        if (self.readU16(flags_offset) != 0) return error.InvalidPage;49        if (self.readU16(overflow_reserved_offset) != 0) return error.InvalidPage;50        if (self.used() == 0 or self.used() > overflow_capacity) return error.InvalidPage;51        if (self.next() != 0 and @as(u64, self.next()) == self.id()) return error.InvalidPage;52    }5354    fn readU16(self: *const Overflow, offset: usize) u16 {55        return std.mem.readInt(u16, self.bytes[offset..][0..2], .big);56    }5758    fn readU32(self: *const Overflow, offset: usize) u32 {59        return std.mem.readInt(u32, self.bytes[offset..][0..4], .big);60    }6162    fn readU64(self: *const Overflow, offset: usize) u64 {63        return std.mem.readInt(u64, self.bytes[offset..][0..8], .big);64    }6566    fn writeU16(self: *Overflow, offset: usize, value: u16) void {67        std.mem.writeInt(u16, self.bytes[offset..][0..2], value, .big);68    }6970    fn writeU32(self: *Overflow, offset: usize, value: u32) void {71        std.mem.writeInt(u32, self.bytes[offset..][0..4], value, .big);72    }7374    fn writeU64(self: *Overflow, offset: usize, value: u64) void {75        std.mem.writeInt(u64, self.bytes[offset..][0..8], value, .big);76    }77};

1pub const OverflowPage = page.Overflow;