zig/lib/std/io/buffered_atomic_file.zig
Andrew Kelley ba0e3be5cf
(breaking) rework stream abstractions
The main goal here is to make the function pointers comptime, so that we
don't have to do the crazy stuff with async function frames.

Since InStream, OutStream, and SeekableStream are already generic
across error sets, it's not really worse to make them generic across the
vtable as well.

See #764 for the open issue acknowledging that using generics for these
abstractions is a design flaw.

See #130 for the efforts to make these abstractions non-generic.

This commit also changes the OutStream API so that `write` returns
number of bytes written, and `writeAll` is the one that loops until the
whole buffer is written.
2020-03-10 15:32:32 -04:00

51 lines
1.8 KiB
Zig

const std = @import("../std.zig");
const mem = std.mem;
const fs = std.fs;
const File = std.fs.File;
pub const BufferedAtomicFile = struct {
atomic_file: fs.AtomicFile,
file_stream: File.OutStream,
buffered_stream: BufferedOutStream,
allocator: *mem.Allocator,
pub const buffer_size = 4096;
pub const BufferedOutStream = std.io.BufferedOutStreamCustom(buffer_size, File.OutStream);
pub const OutStream = std.io.OutStream(*BufferedOutStream, BufferedOutStream.Error, BufferedOutStream.write);
/// TODO when https://github.com/ziglang/zig/issues/2761 is solved
/// this API will not need an allocator
pub fn create(allocator: *mem.Allocator, dest_path: []const u8) !*BufferedAtomicFile {
var self = try allocator.create(BufferedAtomicFile);
self.* = BufferedAtomicFile{
.atomic_file = undefined,
.file_stream = undefined,
.buffered_stream = undefined,
.allocator = allocator,
};
errdefer allocator.destroy(self);
self.atomic_file = try fs.AtomicFile.init(dest_path, File.default_mode);
errdefer self.atomic_file.deinit();
self.file_stream = self.atomic_file.file.outStream();
self.buffered_stream = std.io.bufferedOutStream(buffer_size, self.file_stream);
return self;
}
/// always call destroy, even after successful finish()
pub fn destroy(self: *BufferedAtomicFile) void {
self.atomic_file.deinit();
self.allocator.destroy(self);
}
pub fn finish(self: *BufferedAtomicFile) !void {
try self.buffered_stream.flush();
try self.atomic_file.finish();
}
pub fn stream(self: *BufferedAtomicFile) OutStream {
return .{ .context = &self.buffered_stream };
}
};