From 5656f5090d8646e076db50da03cfc6ae686eb76b Mon Sep 17 00:00:00 2001 From: Andrew Kelley Date: Sat, 2 May 2020 14:08:59 -0400 Subject: [PATCH] fs.File: improve handling async I/O on Windows Before it was possible for .intended_io_mode = .blocking, .capable_io_mode = .evented, and then the implementation would put a request on the fs thread, which is the wrong behavior. Now it always calls the appropriate WriteFile/ReadFile function, passing the intended io mode directly as a parameter. This makes the behavior tests pass on Windows with --test-evented-io. --- lib/std/fs/file.zig | 49 ++++++++++++++++++++++++++++++++++++--------- lib/std/os.zig | 4 ++-- 2 files changed, 42 insertions(+), 11 deletions(-) diff --git a/lib/std/fs/file.zig b/lib/std/fs/file.zig index 08ae1bffca..b7c575a04a 100644 --- a/lib/std/fs/file.zig +++ b/lib/std/fs/file.zig @@ -8,6 +8,7 @@ const assert = std.debug.assert; const windows = os.windows; const Os = builtin.Os; const maxInt = std.math.maxInt; +const is_windows = std.Target.current.os.tag == .windows; pub const File = struct { /// The OS-specific file descriptor or file handle. @@ -119,7 +120,9 @@ pub const File = struct { /// Upon success, the stream is in an uninitialized state. To continue using it, /// you must use the open() function. pub fn close(self: File) void { - if (self.capable_io_mode != self.intended_io_mode) { + if (is_windows) { + windows.CloseHandle(self.handle); + } else if (self.capable_io_mode != self.intended_io_mode) { std.event.Loop.instance.?.close(self.handle); } else { os.close(self.handle); @@ -302,7 +305,9 @@ pub const File = struct { pub const PReadError = os.PReadError; pub fn read(self: File, buffer: []u8) ReadError!usize { - if (self.capable_io_mode != self.intended_io_mode) { + if (is_windows) { + return windows.ReadFile(self.handle, buffer, null, self.intended_io_mode); + } else if (self.capable_io_mode != self.intended_io_mode) { return std.event.Loop.instance.?.read(self.handle, buffer); } else { return os.read(self.handle, buffer); @@ -322,7 +327,9 @@ pub const File = struct { } pub fn pread(self: File, buffer: []u8, offset: u64) PReadError!usize { - if (self.capable_io_mode != self.intended_io_mode) { + if (is_windows) { + return windows.ReadFile(self.handle, buffer, offset, self.intended_io_mode); + } else if (self.capable_io_mode != self.intended_io_mode) { return std.event.Loop.instance.?.pread(self.handle, buffer, offset); } else { return os.pread(self.handle, buffer, offset); @@ -342,7 +349,12 @@ pub const File = struct { } pub fn readv(self: File, iovecs: []const os.iovec) ReadError!usize { - if (self.capable_io_mode != self.intended_io_mode) { + if (is_windows) { + // TODO improve this to use ReadFileScatter + if (iovecs.len == 0) return @as(usize, 0); + const first = iovecs[0]; + return windows.ReadFile(self.handle, first.iov_base[0..first.iov_len], null, self.intended_io_mode); + } else if (self.capable_io_mode != self.intended_io_mode) { return std.event.Loop.instance.?.readv(self.handle, iovecs); } else { return os.readv(self.handle, iovecs); @@ -376,7 +388,12 @@ pub const File = struct { } pub fn preadv(self: File, iovecs: []const os.iovec, offset: u64) PReadError!usize { - if (self.capable_io_mode != self.intended_io_mode) { + if (is_windows) { + // TODO improve this to use ReadFileScatter + if (iovecs.len == 0) return @as(usize, 0); + const first = iovecs[0]; + return windows.ReadFile(self.handle, first.iov_base[0..first.iov_len], offset, self.intended_io_mode); + } else if (self.capable_io_mode != self.intended_io_mode) { return std.event.Loop.instance.?.preadv(self.handle, iovecs, offset); } else { return os.preadv(self.handle, iovecs, offset); @@ -413,7 +430,9 @@ pub const File = struct { pub const PWriteError = os.PWriteError; pub fn write(self: File, bytes: []const u8) WriteError!usize { - if (self.capable_io_mode != self.intended_io_mode) { + if (is_windows) { + return windows.WriteFile(self.handle, bytes, null, self.intended_io_mode); + } else if (self.capable_io_mode != self.intended_io_mode) { return std.event.Loop.instance.?.write(self.handle, bytes); } else { return os.write(self.handle, bytes); @@ -428,7 +447,9 @@ pub const File = struct { } pub fn pwrite(self: File, bytes: []const u8, offset: u64) PWriteError!usize { - if (self.capable_io_mode != self.intended_io_mode) { + if (is_windows) { + return windows.WriteFile(self.handle, bytes, offset, self.intended_io_mode); + } else if (self.capable_io_mode != self.intended_io_mode) { return std.event.Loop.instance.?.pwrite(self.handle, bytes, offset); } else { return os.pwrite(self.handle, bytes, offset); @@ -443,7 +464,12 @@ pub const File = struct { } pub fn writev(self: File, iovecs: []const os.iovec_const) WriteError!usize { - if (self.capable_io_mode != self.intended_io_mode) { + if (is_windows) { + // TODO improve this to use WriteFileScatter + if (iovecs.len == 0) return @as(usize, 0); + const first = iovecs[0]; + return windows.WriteFile(self.handle, first.iov_base[0..first.iov_len], null, self.intended_io_mode); + } else if (self.capable_io_mode != self.intended_io_mode) { return std.event.Loop.instance.?.writev(self.handle, iovecs); } else { return os.writev(self.handle, iovecs); @@ -469,7 +495,12 @@ pub const File = struct { } pub fn pwritev(self: File, iovecs: []os.iovec_const, offset: usize) PWriteError!usize { - if (self.capable_io_mode != self.intended_io_mode) { + if (is_windows) { + // TODO improve this to use WriteFileScatter + if (iovecs.len == 0) return @as(usize, 0); + const first = iovecs[0]; + return windows.WriteFile(self.handle, first.iov_base[0..first.iov_len], offset, self.intended_io_mode); + } else if (self.capable_io_mode != self.intended_io_mode) { return std.event.Loop.instance.?.pwritev(self.handle, iovecs, offset); } else { return os.pwritev(self.handle, iovecs, offset); diff --git a/lib/std/os.zig b/lib/std/os.zig index a1b0dc1991..d605c0eed3 100644 --- a/lib/std/os.zig +++ b/lib/std/os.zig @@ -365,7 +365,7 @@ pub fn read(fd: fd_t, buf: []u8) ReadError!usize { /// On these systems, the read races with concurrent writes to the same file descriptor. pub fn readv(fd: fd_t, iov: []const iovec) ReadError!usize { if (std.Target.current.os.tag == .windows) { - // TODO does Windows have a way to read an io vector? + // TODO improve this to use ReadFileScatter if (iov.len == 0) return @as(usize, 0); const first = iov[0]; return read(fd, first.iov_base[0..first.iov_len]); @@ -651,7 +651,7 @@ pub fn write(fd: fd_t, bytes: []const u8) WriteError!usize { /// If `iov.len` is larger than will fit in a `u31`, a partial write will occur. pub fn writev(fd: fd_t, iov: []const iovec_const) WriteError!usize { if (std.Target.current.os.tag == .windows) { - // TODO does Windows have a way to write an io vector? + // TODO improve this to use WriteFileScatter if (iov.len == 0) return @as(usize, 0); const first = iov[0]; return write(fd, first.iov_base[0..first.iov_len]);