原始问题：Multiple arguments in Gio.Subprocess
所以目前，我正在尝试通过Gio.Subprocess在我的gnome-shell-extension中执行多个异步命令。如果我将所有命令仅作为一个链式命令，并且将&&放在子进程的命令向量中，则此方法很好。该解决方案的缺点是，不同链接命令的输出仅更新一次，执行时间可能很长。
我现在想做的是同时执行每个命令。现在，如果一个命令的间隔很小，而另一条命令需要更多时间，则可以更新输出。
假设这些是我的commands，在这种情况下，我想每秒执行一次每个命令：let命令= {“命令”：[{“命令”：“ ls”，“间隔”：1}，
let commands = {"commands":[{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1}]}
然后我为每个命令调用refresh函数。
commands.commands.forEach(command => {
this.refresh(command);
})
现在正在发生的事情是，gnome UI几乎每秒钟都冻结，而不是很多，但是即使使用异步通信，我也可以在很短的时间内看到鼠标光标或滚动停止。
我从调试中发现，似乎是子进程的初始化导致了小冻结，这也许是因为所有命令几乎同时使用了它？
proc.init(cancellable);
[我认为文档说init方法是同步的（https://developer.gnome.org/gio//2.56/GInitable.html#g-initable-init），而且似乎还有一个异步版本（https://developer.gnome.org/gio//2.56/GAsyncInitable.html#g-async-initable-init-async），但是Gio.Subprocess只实现了同步方法（https://developer.gnome.org/gio//2.56/GSubprocess.html）。
所以最后一个问题是，避免冻结的正确方法是什么？我尝试将init部分移到异步功能，并在完成后继续通过回调执行命令，但是没有运气。也许这甚至是完全错误的方法。
Whole extension.js（为了简单起见，输出的最终更新不是此版本的一部分）：
const Main = imports.ui.main;
const GLib = imports.gi.GLib;
const Mainloop = imports.mainloop;
const Gio = imports.gi.Gio;
const ExtensionUtils = imports.misc.extensionUtils;
const Me = ExtensionUtils.getCurrentExtension();
let output, box, gschema, stopped;
var settings;
let commands = {"commands":[{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1}]}
function init() {
//nothing todo here
}
function enable() {
stopped = false;
gschema = Gio.SettingsSchemaSource.new_from_directory(
Me.dir.get_child('schemas').get_path(),
Gio.SettingsSchemaSource.get_default(),
false
);
settings = new Gio.Settings({
settings_schema: gschema.lookup('org.gnome.shell.extensions.executor', true)
});
box = new St.BoxLayout({ style_class: 'panel-button' });
output = new St.Label();
box.add(output, {y_fill: false, y_align: St.Align.MIDDLE});
Main.panel._rightBox.insert_child_at_index(box, 0);
commands.commands.forEach(command => {
this.refresh(command);
})
}
function disable() {
stopped = true;
log("Executor stopped");
Main.panel._rightBox.remove_child(box);
}
async function refresh(command) {
await this.updateGui(command);
Mainloop.timeout_add_seconds(command.interval, () => {
if (!stopped) {
this.refresh(command);
}
});
}
async function updateGui(command) {
await execCommand(['/bin/sh', '-c', command.command]).then(stdout => {
if (stdout) {
let entries = [];
stdout.split('\n').map(line => entries.push(line));
let outputAsOneLine = '';
entries.forEach(output => {
outputAsOneLine = outputAsOneLine + output + ' ';
});
if (!stopped) {
log(outputAsOneLine);
//output.set_text(outputAsOneLine);
}
}
});
}
async function execCommand(argv, input = null, cancellable = null) {
try {
let flags = Gio.SubprocessFlags.STDOUT_PIPE;
if (input !== null)
flags |= Gio.SubprocessFlags.STDIN_PIPE;
let proc = new Gio.Subprocess({
argv: argv,
flags: flags
});
proc.init(cancellable);
let stdout = await new Promise((resolve, reject) => {
proc.communicate_utf8_async(input, cancellable, (proc, res) => {
try {
let [ok, stdout, stderr] = proc.communicate_utf8_finish(res);
resolve(stdout);
} catch (e) {
reject(e);
}
});
});
return stdout;
} catch (e) {
logError(e);
}
}```
function execCommand(argv, input = null, cancellable = null) {
try {
/* If you expect to get output from stderr, you need to open
* that pipe as well, otherwise you will just get `null`. */
let flags = (Gio.SubprocessFlags.STDOUT_PIPE |
Gio.SubprocessFlags.STDERR_PIPE);
if (input !== null)
flags |= Gio.SubprocessFlags.STDIN_PIPE;
/* Using `new` with an initable class like this is only really
* necessary if it's possible you might pass a pre-triggered
* cancellable, so you can call `init()` manually.
*
* Otherwise you can just use `Gio.Subprocess.new()` which will
* do exactly the same thing for you, just in a single call
* without a cancellable argument. */
let proc = new Gio.Subprocess({
argv: argv,
flags: flags
});
proc.init(cancellable);
/* If you want to actually quit the process when the cancellable
* is triggered, you need to connect to the `cancel` signal */
if (cancellable instanceof Gio.Cancellable)
cancellable.connect(() => proc.force_exit());
/* Remember the process start running as soon as we called
* `init()`, so this is just the threaded call to read the
* processes's output.
*/
return new Promise((resolve, reject) => {
proc.communicate_utf8_async(input, cancellable, (proc, res) => {
try {
let [, stdout, stderr] = proc.communicate_utf8_finish(res);
/* If you do opt for stderr output, you might as
* well use it for more informative errors */
if (!proc.get_successful()) {
let status = proc.get_exit_status();
throw new Gio.IOErrorEnum({
code: Gio.io_error_from_errno(status),
message: stderr ? stderr.trim() : GLib.strerror(status)
});
}
resolve(stdout);
} catch (e) {
reject(e);
}
});
});
/* This should only happen if you passed a pre-triggered cancellable
* or the process legitimately failed to start (eg. commmand not found) */
} catch (e) {
return Promise.reject(e);
}
}
以及关于Promise / async用法的注释：
/* Don't do this. You're effectively mixing two usage patterns
* of Promises, and still not catching errors. Expect this to
* blow up in your face long after you expect it to. */
async function foo() {
await execCommand(['ls']).then(stdout => log(stdout));
}
/* If you're using `await` in an `async` function that is
* intended to run by itself, you need to catch errors like
* regular synchronous code */
async function bar() {
try {
// The function will "await" the first Promise to
// resolve successfully before executing the second
await execCommand(['ls']);
await execCommand(['ls']);
} catch (e) {
logError(e);
}
}
/* If you're using Promises in the traditional manner, you
* must catch them that way as well */
function baz() {
// The function will NOT wait for the first to complete
// before starting the second. Since these are (basically)
// running in threads, they are truly running in parallel.
execCommand(['ls']).then(stdout => {
log(stdout);
}).catch(error => {
logError(error);
});
execCommand(['ls']).then(stdout => {
log(stdout);
}).catch(error => {
logError(error);
});
}
现在执行：
const Main = imports.ui.main;
const GLib = imports.gi.GLib;
const Gio = imports.gi.Gio;
const ExtensionUtils = imports.misc.extensionUtils;
const Me = ExtensionUtils.getCurrentExtension();
let cancellable = null;
let panelBox = null;
let commands = {
"commands":[
{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1},
{"command":"ls","interval":1}
]
};
enable() {
if (cancellable === null)
cancellable = new Gio.Cancellable();
panelBox = new St.BoxLayout({
style_class: 'panel-button'
});
// Avoid deprecated methods like `add()`, and try not
// to use global variable when possible
let outputLabel = new St.Label({
y_align: St.Align.MIDDLE,
y_fill: false
});
panelBox.add_child(outputLabel);
Main.panel._rightBox.insert_child_at_index(panelBox, 0);
commands.commands.forEach(command => {
this.refresh(command);
});
}
disable() {
if (cancellable !== null) {
cancellable.cancel();
cancellable = null;
}
log("Executor stopped");
if (panelBox !== null) {
Main.panel._rightBox.remove_child(panelBox);
panelBox = null;
}
}
async function refresh(command) {
try {
await this.updateGui(command);
// Don't use MainLoop anymore, just use GLib directly
GLib.timeout_add_seconds(0, command.interval, () => {
if (cancellable && !cancellable.is_cancelled())
this.refresh(command);
// Always explicitly return false (or this constant)
// unless you're storing the returned ID to remove the
// source later.
//
// Returning true (GLib.SOURCE_CONTINUE) or a value that
// evaluates to true will cause the source to loop. You
// could refactor your code to take advantage of that
// instead of constantly creating new timeouts each
// second.
return GLib.SOURCE_REMOVE;
});
} catch (e) {
// We can skip logging cancelled errors, since we probably
// did that on purpose if it happens
if (!e.matches(Gio.IOErrorEnum, Gio.IOErrorEnum.CANCELLED)
logError(e, 'Failed to refresh');
}
}
// `updateGui()` is wrapped in a try...catch above so it's safe to
// skip that here.
async function updateGui(command) {
let stdout = await execCommand(['/bin/sh', '-c', command.command]);
// This will probably always be true if the above doesn't throw,
// but you can check if you want to.
if (stdout) {
let outputAsOneLine = stdout.replace('\n', '');
// No need to check the cancellable here, if it's
// triggered the command will fail and throw an error
log(outputAsOneLine);
// let outputLabel = panelBox.get_first_child();
// outputLabel.set_text(outputAsOneLine);
}
}
很难说是什么原因导致了您遇到的冻结，但是我首先要清理Promise用法，并更明确地说明如何使用超时源，因为这些超时源可能每秒都在堆积。
[如果可能，您可能希望将子流程分组为一个超时源，可以使用Promise.all()一次等待它们。用未决的源和承诺重载事件循环也可能是冻结的原因。