zig/lib/std/progress.zig
2019-12-08 22:53:51 -05:00

256 lines
9.4 KiB
Zig

const std = @import("std");
const testing = std.testing;
const assert = std.debug.assert;
/// This API is non-allocating and non-fallible. The tradeoff is that users of
/// this API must provide the storage for each `Progress.Node`.
/// Initialize the struct directly, overriding these fields as desired:
/// * `refresh_rate_ms`
/// * `initial_delay_ms`
pub const Progress = struct {
/// `null` if the current node (and its children) should
/// not print on update()
terminal: ?std.fs.File = undefined,
root: Node = undefined,
/// Keeps track of how much time has passed since the beginning.
/// Used to compare with `initial_delay_ms` and `refresh_rate_ms`.
timer: std.time.Timer = undefined,
/// When the previous refresh was written to the terminal.
/// Used to compare with `refresh_rate_ms`.
prev_refresh_timestamp: u64 = undefined,
/// This buffer represents the maximum number of bytes written to the terminal
/// with each refresh.
output_buffer: [100]u8 = undefined,
/// How many nanoseconds between writing updates to the terminal.
refresh_rate_ns: u64 = 50 * std.time.millisecond,
/// How many nanoseconds to keep the output hidden
initial_delay_ns: u64 = 500 * std.time.millisecond,
done: bool = true,
/// Keeps track of how many columns in the terminal have been output, so that
/// we can move the cursor back later.
columns_written: usize = undefined,
/// Represents one unit of progress. Each node can have children nodes, or
/// one can use integers with `update`.
pub const Node = struct {
context: *Progress,
parent: ?*Node,
completed_items: usize,
name: []const u8,
recently_updated_child: ?*Node = null,
/// This field may be updated freely.
estimated_total_items: ?usize,
/// Create a new child progress node.
/// Call `Node.end` when done.
/// TODO solve https://github.com/ziglang/zig/issues/2765 and then change this
/// API to set `self.parent.recently_updated_child` with the return value.
/// Until that is fixed you probably want to call `activate` on the return value.
pub fn start(self: *Node, name: []const u8, estimated_total_items: ?usize) Node {
return Node{
.context = self.context,
.parent = self,
.completed_items = 0,
.name = name,
.estimated_total_items = estimated_total_items,
};
}
/// This is the same as calling `start` and then `end` on the returned `Node`.
pub fn completeOne(self: *Node) void {
if (self.parent) |parent| parent.recently_updated_child = self;
self.completed_items += 1;
self.context.maybeRefresh();
}
pub fn end(self: *Node) void {
self.context.maybeRefresh();
if (self.parent) |parent| {
if (parent.recently_updated_child) |parent_child| {
if (parent_child == self) {
parent.recently_updated_child = null;
}
}
parent.completeOne();
} else {
self.context.done = true;
self.context.refresh();
}
}
/// Tell the parent node that this node is actively being worked on.
pub fn activate(self: *Node) void {
if (self.parent) |parent| parent.recently_updated_child = self;
}
};
/// Create a new progress node.
/// Call `Node.end` when done.
/// TODO solve https://github.com/ziglang/zig/issues/2765 and then change this
/// API to return Progress rather than accept it as a parameter.
pub fn start(self: *Progress, name: []const u8, estimated_total_items: ?usize) !*Node {
const stderr = std.io.getStdErr();
self.terminal = if (stderr.supportsAnsiEscapeCodes()) stderr else null;
self.root = Node{
.context = self,
.parent = null,
.completed_items = 0,
.name = name,
.estimated_total_items = estimated_total_items,
};
self.columns_written = 0;
self.prev_refresh_timestamp = 0;
self.timer = try std.time.Timer.start();
self.done = false;
return &self.root;
}
/// Updates the terminal if enough time has passed since last update.
pub fn maybeRefresh(self: *Progress) void {
const now = self.timer.read();
if (now < self.initial_delay_ns) return;
if (now - self.prev_refresh_timestamp < self.refresh_rate_ns) return;
self.refresh();
}
/// Updates the terminal and resets `self.next_refresh_timestamp`.
pub fn refresh(self: *Progress) void {
const file = self.terminal orelse return;
const prev_columns_written = self.columns_written;
var end: usize = 0;
if (self.columns_written > 0) {
// restore cursor position
end += (std.fmt.bufPrint(self.output_buffer[end..], "\x1b[{}D", .{self.columns_written}) catch unreachable).len;
self.columns_written = 0;
// clear rest of line
end += (std.fmt.bufPrint(self.output_buffer[end..], "\x1b[0K", .{}) catch unreachable).len;
}
if (!self.done) {
var need_ellipse = false;
var maybe_node: ?*Node = &self.root;
while (maybe_node) |node| {
if (need_ellipse) {
self.bufWrite(&end, "...", .{});
}
need_ellipse = false;
if (node.name.len != 0 or node.estimated_total_items != null) {
if (node.name.len != 0) {
self.bufWrite(&end, "{}", .{node.name});
need_ellipse = true;
}
if (node.estimated_total_items) |total| {
if (need_ellipse) self.bufWrite(&end, " ", .{});
self.bufWrite(&end, "[{}/{}] ", .{ node.completed_items + 1, total });
need_ellipse = false;
} else if (node.completed_items != 0) {
if (need_ellipse) self.bufWrite(&end, " ", .{});
self.bufWrite(&end, "[{}] ", .{node.completed_items + 1});
need_ellipse = false;
}
}
maybe_node = node.recently_updated_child;
}
if (need_ellipse) {
self.bufWrite(&end, "...", .{});
}
}
_ = file.write(self.output_buffer[0..end]) catch |e| {
// Stop trying to write to this file once it errors.
self.terminal = null;
};
self.prev_refresh_timestamp = self.timer.read();
}
pub fn log(self: *Progress, comptime format: []const u8, args: var) void {
const file = self.terminal orelse return;
self.refresh();
file.outStream().stream.print(format, args) catch {
self.terminal = null;
return;
};
self.columns_written = 0;
}
fn bufWrite(self: *Progress, end: *usize, comptime format: []const u8, args: var) void {
if (std.fmt.bufPrint(self.output_buffer[end.*..], format, args)) |written| {
const amt = written.len;
end.* += amt;
self.columns_written += amt;
} else |err| switch (err) {
error.BufferTooSmall => {
self.columns_written += self.output_buffer.len - end.*;
end.* = self.output_buffer.len;
},
}
const bytes_needed_for_esc_codes_at_end = 11;
const max_end = self.output_buffer.len - bytes_needed_for_esc_codes_at_end;
if (end.* > max_end) {
const suffix = "...";
self.columns_written = self.columns_written - (end.* - max_end) + suffix.len;
std.mem.copy(u8, self.output_buffer[max_end..], suffix);
end.* = max_end + suffix.len;
}
}
};
test "basic functionality" {
var disable = true;
if (disable) {
// This test is disabled because it uses time.sleep() and is therefore slow. It also
// prints bogus progress data to stderr.
return error.SkipZigTest;
}
var progress = Progress{};
const root_node = try progress.start("", 100);
defer root_node.end();
const sub_task_names = [_][]const u8{
"reticulating splines",
"adjusting shoes",
"climbing towers",
"pouring juice",
};
var next_sub_task: usize = 0;
var i: usize = 0;
while (i < 100) : (i += 1) {
var node = root_node.start(sub_task_names[next_sub_task], 5);
node.activate();
next_sub_task = (next_sub_task + 1) % sub_task_names.len;
node.completeOne();
std.time.sleep(5 * std.time.millisecond);
node.completeOne();
node.completeOne();
std.time.sleep(5 * std.time.millisecond);
node.completeOne();
node.completeOne();
std.time.sleep(5 * std.time.millisecond);
node.end();
std.time.sleep(5 * std.time.millisecond);
}
{
var node = root_node.start("this is a really long name designed to activate the truncation code. let's find out if it works", null);
node.activate();
std.time.sleep(10 * std.time.millisecond);
progress.refresh();
std.time.sleep(10 * std.time.millisecond);
node.end();
}
}