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io_uring: replace the readv method with a read on a new ReadBuffer type

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readv() is essentially identical to read() except for the buffer type,
this simplifies the API for the caller at the cost of not clearly mapping to the liburing C API.
This commit is contained in:
Vincent Rischmann 2022-05-20 20:41:56 +02:00
parent acb8af468f
commit 3c58d3e281
1 changed files with 11 additions and 20 deletions
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31
lib/std/os/linux/io_uring.zig
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@ -363,6 +363,9 @@ pub const IO_Uring = struct {
/// io_uring will read directly into this buffer
buffer: []u8,
/// io_uring will read directly into these buffers using readv.
iovecs: []const os.iovec,
/// io_uring will select a buffer that has previously been provided with `provide_buffers`.
/// The buffer group reference by `group_id` must contain at least one buffer for the read to work.
/// `len` controls the number of bytes to read into the selected buffer.
@ -372,7 +375,11 @@ pub const IO_Uring = struct {
},
};
/// Queues (but does not submit) an SQE to perform a `read(2)`.
/// Queues (but does not submit) an SQE to perform a `read(2)` or `preadv` depending on the buffer type.
/// * Reading into a `ReadBuffer.buffer` uses `read(2)`
/// * Reading into a `ReadBuffer.iovecs` uses `preadv(2)`
/// If you want to do a `preadv2()` then set `rw_flags` on the returned SQE. See https://linux.die.net/man/2/preadv.
///
/// Returns a pointer to the SQE.
pub fn read(
self: *IO_Uring,
@ -384,6 +391,7 @@ pub const IO_Uring = struct {
const sqe = try self.get_sqe();
switch (buffer) {
.buffer => |slice| io_uring_prep_read(sqe, fd, slice, offset),
.iovecs => |vecs| io_uring_prep_readv(sqe, fd, vecs, offset),
.buffer_selection => |selection| {
io_uring_prep_rw(.READ, sqe, fd, 0, selection.len, offset);
sqe.flags |= linux.IOSQE_BUFFER_SELECT;
@ -409,23 +417,6 @@ pub const IO_Uring = struct {
return sqe;
}
/// Queues (but does not submit) an SQE to perform a `preadv()`.
/// Returns a pointer to the SQE so that you can further modify the SQE for advanced use cases.
/// For example, if you want to do a `preadv2()` then set `rw_flags` on the returned SQE.
/// See https://linux.die.net/man/2/preadv.
pub fn readv(
self: *IO_Uring,
user_data: u64,
fd: os.fd_t,
iovecs: []const os.iovec,
offset: u64,
) !*io_uring_sqe {
const sqe = try self.get_sqe();
io_uring_prep_readv(sqe, fd, iovecs, offset);
sqe.user_data = user_data;
return sqe;
}
/// Queues (but does not submit) an SQE to perform a IORING_OP_READ_FIXED.
/// The `buffer` provided must be registered with the kernel by calling `register_buffers` first.
/// The `buffer_index` must be the same as its index in the array provided to `register_buffers`.
@ -1715,7 +1706,7 @@ test "readv" {
var buffer = [_]u8{42} ** 128;
var iovecs = [_]os.iovec{os.iovec{ .iov_base = &buffer, .iov_len = buffer.len }};
const sqe = try ring.readv(0xcccccccc, fd_index, iovecs[0..], 0);
const sqe = try ring.read(0xcccccccc, fd_index, .{ .iovecs = iovecs[0..] }, 0);
try testing.expectEqual(linux.IORING_OP.READV, sqe.opcode);
sqe.flags |= linux.IOSQE_FIXED_FILE;
@ -1766,7 +1757,7 @@ test "writev/fsync/readv" {
try testing.expectEqual(fd, sqe_fsync.fd);
sqe_fsync.flags |= linux.IOSQE_IO_LINK;
const sqe_readv = try ring.readv(0xffffffff, fd, iovecs_read[0..], 17);
const sqe_readv = try ring.read(0xffffffff, fd, .{ .iovecs = iovecs_read[0..] }, 17);
try testing.expectEqual(linux.IORING_OP.READV, sqe_readv.opcode);
try testing.expectEqual(@as(u64, 17), sqe_readv.off);