tiny.sys.poll

1const std = @import("std");2const builtin = @import("builtin");3const capabilities = @import("capabilities.zig");45const native_os = builtin.os.tag;6const posix = std.posix;78pub const required_capabilities = switch (native_os) {9    .linux => capabilities.noLibc(&.{ .descriptors, .event_loop }),10    else => capabilities.host(&.{ .descriptors, .event_loop }),11};1213pub const Descriptor = posix.pollfd;14pub const TimeSpec = posix.timespec;15pub const SignalSet = posix.sigset_t;16pub const WaitError = posix.PollError || error{UnsupportedPlatform};17pub const PreciseWaitError = posix.PPollError || error{UnsupportedPlatform};1819pub const Event = struct {20    pub const input = posix.POLL.IN;21    pub const output = posix.POLL.OUT;22    pub const error_condition = posix.POLL.ERR;23    pub const hangup = posix.POLL.HUP;24    pub const invalid = posix.POLL.NVAL;25};2627pub fn wait(descriptors: []Descriptor, timeout_ms: i32) WaitError!usize {28    if (comptime !supported()) return error.UnsupportedPlatform;29    return posix.poll(descriptors, timeout_ms);30}3132pub fn waitPrecise(33    descriptors: []Descriptor,34    timeout: ?*const TimeSpec,35    signal_mask: ?*const SignalSet,36) PreciseWaitError!usize {37    if (comptime !preciseSupported()) return error.UnsupportedPlatform;38    return posix.ppoll(descriptors, timeout, signal_mask);39}4041/// Whether `waitPrecise` runs here. Apple's libc has no `ppoll`.42pub fn preciseSupported() bool {43    return supported() and !native_os.isDarwin();44}4546pub fn supported() bool {47    return switch (native_os) {48        .windows, .wasi, .freestanding => false,49        else => true,50    };51}5253test "poll waits preserve descriptor readiness" {54    if (!supported()) return error.SkipZigTest;55    const fd = @import("fd.zig");56    const descriptors = try fd.pipeWithOptions(.{});57    defer fd.close(descriptors[0]);58    defer fd.close(descriptors[1]);5960    var poll_descriptors = [_]Descriptor{.{61        .fd = descriptors[0],62        .events = Event.input,63        .revents = 0,64    }};65    try std.testing.expectEqual(@as(usize, 0), try wait(&poll_descriptors, 0));66    try std.testing.expectEqual(@as(usize, 1), try fd.write(descriptors[1], "x"));67    try std.testing.expectEqual(@as(usize, 1), try wait(&poll_descriptors, 0));6869    if (!preciseSupported()) return;70    const timeout = TimeSpec{ .sec = 0, .nsec = 0 };71    try std.testing.expectEqual(72        @as(usize, 1),73        try waitPrecise(&poll_descriptors, &timeout, null),74    );75}

1pub const poll = @import("poll.zig");