libuv: stream writes

src/libuv/Pipe.zig

@@ -10,7 +10,9 @@ const c = @import("c.zig");
 const errors = @import("error.zig");
 const Loop = @import("Loop.zig");
 const Handle = @import("handle.zig").Handle;
-const Stream = @import("stream.zig").Stream;
+const stream = @import("stream.zig");
+const Stream = stream.Stream;
+const WriteReq = stream.WriteReq;
 
 handle: *c.uv_pipe_t,
 
@@ -33,17 +35,23 @@ pub const Flags = packed struct {
     }
 };
 
+/// Pair is a pair of ends to a single pipe.
+pub const Pair = struct {
+    read: c.uv_file,
+    write: c.uv_file,
+};
+
 /// Create a pair of connected pipe handles. Data may be written to fds[1] and
 /// read from fds[0]. The resulting handles can be passed to uv_pipe_open,
 /// used with uv_spawn, or for any other purpose.
-pub fn pipe(read_flags: Flags, write_flags: Flags) ![2]c.uv_file {
+pub fn pipe(read_flags: Flags, write_flags: Flags) !Pair {
     var res: [2]c.uv_file = undefined;
     try errors.convertError(c.uv_pipe(
         &res,
         read_flags.toInt(c_int),
         write_flags.toInt(c_int),
     ));
-    return res;
+    return Pair{ .read = res[0], .write = res[1] };
 }
 
 pub fn init(alloc: Allocator, loop: Loop, ipc: bool) !Pipe {
@@ -68,18 +76,61 @@ test {
 }
 
 test "Pipe" {
-    const pipes = try pipe(.{ .nonblock = true }, .{ .nonblock = true });
-    defer std.os.close(pipes[1]);
+    const pair = try pipe(.{ .nonblock = true }, .{ .nonblock = true });
 
     var loop = try Loop.init(testing.allocator);
     defer loop.deinit(testing.allocator);
-    var h = try init(testing.allocator, loop, false);
-    defer h.deinit(testing.allocator);
 
-    try h.open(pipes[0]);
-    try testing.expect(try h.isReadable());
-    try testing.expect(!try h.isWritable());
+    // Read side
+    var reader = try init(testing.allocator, loop, false);
+    defer reader.deinit(testing.allocator);
 
-    h.close(null);
+    try reader.open(pair.read);
+    try testing.expect(try reader.isReadable());
+    try testing.expect(!try reader.isWritable());
+
+    // Write side
+    var writer = try init(testing.allocator, loop, false);
+    defer writer.deinit(testing.allocator);
+
+    try writer.open(pair.write);
+    try testing.expect(!try writer.isReadable());
+    try testing.expect(try writer.isWritable());
+
+    // Set our data that we'll use to assert
+    var data: TestData = .{};
+    writer.setData(&data);
+
+    // Write
+    var writeReq = try WriteReq.init(testing.allocator);
+    defer writeReq.deinit(testing.allocator);
+
+    try writer.write(
+        writeReq,
+        &[_][]const u8{
+            "hello",
+        },
+        callback,
+    );
+
+    // Run write and verify success
+    _ = try loop.run(.once);
+    try testing.expectEqual(@as(u8, 1), data.count);
+    try testing.expectEqual(@as(i32, 0), data.status);
+
+    // End
+    reader.close(null);
+    writer.close(null);
     _ = try loop.run(.default);
 }
+
+const TestData = struct {
+    count: u8 = 0,
+    status: i32 = 0,
+};
+
+fn callback(req: *WriteReq, status: i32) void {
+    var data = req.handle(Pipe).?.getData(TestData).?;
+    data.count += 1;
+    data.status = status;
+}

src/libuv/main.zig

@@ -10,6 +10,7 @@ pub const Error = @import("error.zig").Error;
 pub const Embed = @import("Embed.zig");
 
 test {
+    _ = @import("stream.zig");
     _ = @import("tests.zig");
 
     _ = Loop;

src/libuv/stream.zig

@@ -1,7 +1,11 @@
 const c = @import("c.zig");
 
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+const testing = std.testing;
 const Loop = @import("Loop.zig");
 const errors = @import("error.zig");
+const Error = errors.Error;
 
 /// Returns a struct that has all the shared stream functions for the
 /// given stream type T. The type T must have a field named "handle".
@@ -29,5 +33,83 @@ pub fn Stream(comptime T: type) type {
             try errors.convertError(res);
             return res > 0;
         }
+
+        /// Write data to stream. Buffers are written in order.
+        pub fn write(
+            self: T,
+            req: WriteReq,
+            bufs: []const []const u8,
+            comptime cb: fn (req: *WriteReq, status: i32) void,
+        ) !void {
+            const Wrapper = struct {
+                fn callback(cbreq: [*c]c.uv_write_t, status: c_int) callconv(.C) void {
+                    var newreq: WriteReq = .{ .req = cbreq };
+                    @call(.{ .modifier = .always_inline }, cb, .{
+                        &newreq,
+                        @intCast(i32, status),
+                    });
+                }
+            };
+
+            // We can directly ptrCast bufs.ptr to a C pointer of uv_buf_t
+            // because they have the exact same layout in memory. We have a
+            // unit test below that keeps this true.
+            try errors.convertError(c.uv_write(
+                req.req,
+                @ptrCast(*c.uv_stream_t, self.handle),
+                @ptrCast([*c]const c.uv_buf_t, bufs.ptr),
+                @intCast(c_uint, bufs.len),
+                Wrapper.callback,
+            ));
+        }
     };
 }
+
+/// Write request type. Careful attention must be paid when reusing objects
+/// of this type. When a stream is in non-blocking mode, write requests sent
+/// with uv_write will be queued. Reusing objects at this point is undefined
+/// behaviour. It is safe to reuse the uv_write_t object only after the
+/// callback passed to uv_write is fired.
+pub const WriteReq = struct {
+    req: *c.uv_write_t,
+
+    pub fn init(alloc: Allocator) !WriteReq {
+        var req = try alloc.create(c.uv_write_t);
+        errdefer alloc.destroy(req);
+        return WriteReq{ .req = req };
+    }
+
+    pub fn deinit(self: *WriteReq, alloc: Allocator) void {
+        alloc.destroy(self.req);
+        self.* = undefined;
+    }
+
+    /// Pointer to the stream where this write request is running.
+    /// T should be a high-level handle type such as "Pipe".
+    pub fn handle(self: WriteReq, comptime T: type) ?T {
+        const tInfo = @typeInfo(T).Struct;
+        const HandleType = tInfo.fields[0].field_type;
+
+        return if (self.req.handle) |ptr|
+            return T{ .handle = @ptrCast(HandleType, ptr) }
+        else
+            null;
+    }
+
+    test "Write: create and destroy" {
+        var h = try init(testing.allocator);
+        defer h.deinit(testing.allocator);
+    }
+};
+
+test {
+    _ = WriteReq;
+}
+
+test "uv_buf_t and slices are the same" {
+    // Verify that the fields are also the same
+    var slice: []const u8 = &[_]u8{ 1, 2, 3 };
+    var buf = @bitCast(c.uv_buf_t, slice);
+    try testing.expectEqual(slice.ptr, buf.base);
+    try testing.expectEqual(slice.len, buf.len);
+}