Dart HttpClient.getUrl invoked by Timer without client or http server - dart

Question

EDIT: Problem wasn't related to Timer or HttpServer, it was dart.io sleep function pausing everything. It is clearly described in documentation, my bad.
//
I have weird problem with HttpClient working in server code. I call
client.getUrl(Uri.parse(url)).then((HttpClientRequest response) => response.close()).then(HttpBodyHandler.processResponse).then((HttpClientResponseBody body) {
print(body.response.statusCode);
from Timer object and it never reach print step.
It is almost copy and paste code from previous version, which wasn't called from Timer but from HttpRequest. Working code is in my question [here][1].
It fails on the long line, I suspect that it is a last Future it never reach (HttpClientResponseBody).
Timer object is created like this (just test code):
main() {
t = new Timer.periodic(new Duration(minutes: period), (Timer t) => hit());
}
void hit() {
if (new DateTime.now().hour == 17) {
print("syncing rock");
loadUrlBody(furl + filter).then((content) {
print("content loaded");
//edit:
okay, here is the source, it might be some trivial problem..which I can't figure out for two days :-D
import 'dart:async';
import 'dart:io';
import 'package:http_server/http_server.dart';
import 'package:slack/slack_io.dart' as slack;
Timer t;
bool check;
final period = 1;
final furl = "https://****.tpondemand.com";
final filter = "somefilter";
main() {
t = new Timer.periodic(new Duration(minutes: period), (Timer t) => hit());
}
void hit() {
if (new DateTime.now().hour == 17) {
print("syncing rock");
loadUrlBody(furl + filter).then((content) {
print("content loaded");
Map parsedMap = content.body;
handleMap(parsedMap);
});
sleep(new Duration(minutes: 60));
} else {
print("no time to rock " + new DateTime.now().toString());
sleep(new Duration(minutes: period * 10));
}
}
Future loadUrlBody(String url) {
final c = new Completer();
HttpClient client = new HttpClient();
client.addCredentials(Uri.parse("https://****.tpondemand.com/api"), "tprealm", new HttpClientBasicCredentials("user", "password"));
client.getUrl(Uri.parse(url)).then((HttpClientRequest response) => response.close()).then(HttpBodyHandler.processResponse).then((HttpClientResponseBody body) {
print(body.response.statusCode);
c.complete(body);
});
return c.future;
}
void send2Slack(String m) {
slack.Message message = new slack.Message()..text = m;
slack.token = 'token';
slack.team = 'team';
slack.send(message);
}
void handleMap(Map valueMap) {
final Duration lostInTime = new Duration(days: 30);
var sb = new StringBuffer();
sb.write('K o m p o s t \n');
for (var item in valueMap["Items"]) {
if (item['CreateDate'] == null) item['CreateDate'] = '/Date(1403167885000+0100)/';
if (item['ModifyDate'] == null) item['ModifyDate'] = '/Date(1403167885000+0100)/';
if (item['LastCommentDate'] == null) item['LastCommentDate'] = '/Date(1403167885000+0100)/';
DateTime moonLanding = new DateTime.fromMillisecondsSinceEpoch(int.parse(item['CreateDate'].substring(6, 19)));
DateTime modifyLanding = new DateTime.fromMillisecondsSinceEpoch(int.parse(item['ModifyDate'].substring(6, 19)));
DateTime commentLanding = new DateTime.fromMillisecondsSinceEpoch(int.parse(item['LastCommentDate'].substring(6, 19)));
DateTime lastChangeLanding = (modifyLanding.isBefore(commentLanding)) ? commentLanding : modifyLanding;
Duration difference = new DateTime.now().difference(lastChangeLanding);
if (moonLanding.add(lostInTime).isBefore(new DateTime.now()) && difference.inDays > 4) {
sb
..write('<https://****.tpondemand.com/entity/')
..write(item['Id'])
..write('|')
..write(item['Name'])
..write('> last change: ')
..write(difference.inDays)
..write(' days ago \n');
}
;
}
send2Slack(sb.toString());
print("sent to Slack");
sb.clear();
}

Answer 1

I created similar code but I can't reproduce your problem.
So basically this does work when called from a Timer.
import 'dart:io';
import 'dart:async';
import 'package:http_server/http_server.dart';
Timer t;
final period = 1;
void main(args) {
t = new Timer.periodic(new Duration(minutes: period), (Timer t) => hit());
}
void hit() {
loadUrlBody('http://www.google.com')
.then((HttpClientResponseBody b) => print('hit: ${b.response.statusCode}'));
}
Future loadUrlBody(String url) {
print('executing');
HttpClient client = new HttpClient();
// commented out because I have no server where I can use it
// HttpClient client = new HttpClient()
// ..addCredentials(Uri.parse("https://****.tpondemand.com/api"), "tprealm", new HttpClientBasicCredentials("user", "password"));
return client.getUrl(Uri.parse(url)) // <== return is important here
.then((HttpClientRequest response) => response.close())
.then(HttpBodyHandler.processResponse)
.then((HttpClientResponseBody body) {
print('body: (${new DateTime.now()}) ${body.response.statusCode}');
return body; // <== this value is the value the next 'then' receives.
// for example x in: loadUrlBody('http://someurl').then(x) => doSomething(x));
});
}
You don't need to use a Completer. Completer are for more complicated used cases where for example one method returns a Completer and for example an eventHandler completes it.
You just have to ensure that you return a Future everywhere. then always returns a Future. The value of the returned Future is the value returned inside then.