1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
use crate::auxiliary::*;
use crate::*;
use anyhow::{anyhow, bail, Result};
use async_channel::*;
use reqwest::{Client, Url};
use scraper::{Html, Selector};
use std::collections::{HashMap, HashSet, VecDeque};
use std::sync::Arc;
/// A crawler object, use builder() to build with CrawlerBuilder
pub struct Crawler<'a> {
handlers: HashMap<HandlerEvent, Vec<Handler<'a>>>,
propagators: HashMap<HandlerEvent, Vec<Propagator<'a>>>,
depth: usize,
workers: usize,
client: Arc<Client>,
blacklist: Vec<String>,
whitelist: Vec<String>,
visited: HashSet<String>,
revisit: bool,
}
impl<'a> Crawler<'a> {
/// Get a CrawlerBuilder
/// Equivalent to `CrawlerBuilder::new()`
pub fn builder() -> CrawlerBuilder<'a> {
CrawlerBuilder::new()
}
/// Create a crawler, consuming a CrawlerBuilder
/// Equivalent to `CrawlerBuilder.build()`
pub fn from_builder(builder: CrawlerBuilder<'a>) -> Result<Self> {
Ok(Self {
handlers: builder.handlers,
propagators: builder.propagators,
depth: builder.depth,
workers: builder.workers,
client: Arc::new(builder.client_builder.build()?),
blacklist: builder.blacklist,
whitelist: builder.whitelist,
visited: HashSet::new(),
revisit: builder.revisit,
})
}
/// Start crawling at the provided URL and return errors that occur
pub async fn crawl(&mut self, start_url: &str) -> Result<Vec<anyhow::Error>> {
let uri: Url = Url::parse(start_url)?;
let mut errors = vec![];
let mut seen: HashSet<Url> = HashSet::new();
seen.insert(uri.clone());
// set up async
let mut queue: VecDeque<(Url, usize)> = VecDeque::new();
queue.push_back((uri.clone(), 0));
let (s, r) = bounded(self.workers);
let mut tasks = 0;
// Loop while the queue is not empty or tasks are fetching pages.
while queue.len() + tasks > 0 {
// Limit the number of concurrent tasks.
while tasks < s.capacity().unwrap() {
// Process URLs in the queue and fetch more pages.
match queue.pop_front() {
None => break,
Some(url) => {
tasks += 1;
tokio::spawn(Self::fetch(url.0, url.1, self.client.clone(), s.clone()));
}
}
}
// Recieve a message
let fetched = r.recv().await.unwrap();
tasks -= 1;
if let Err(fetch_err) = fetched {
errors.push(fetch_err);
continue;
}
// wrap up data for handlers
let (url, text, depth) = fetched.unwrap();
let doc = Html::parse_document(&text);
let page = Page {
url,
text,
doc,
depth,
};
self.do_handlers(&page)?;
if depth < self.depth {
self.do_propagators(&page, &mut queue)?;
}
}
Ok(errors)
}
fn do_propagators(&mut self, page: &Page, queue: &mut VecDeque<(Url, usize)>) -> Result<()> {
let wl = &self.whitelist;
let bl = &self.blacklist;
let mut visited = &mut self.visited;
let revisit = self.revisit;
for (kind, props) in self.propagators.iter_mut() {
match kind {
HandlerEvent::OnSelector(sel) => {
if let Ok(sel) = Selector::parse(&sel) {
props.iter_mut().for_each(|propagator| {
page.doc.select(&sel).for_each(|el| {
propagator(&HandlerArgs {
page,
element: Some(el),
client: self.client.clone(),
})
.iter()
.filter(|u| {
is_allowed(u, wl, bl)
&& (revisit || !is_visited(u, &mut visited))
})
.for_each(|u| {
queue.push_back((u.clone(), page.depth + 1));
});
});
});
} else {
bail!("invalid selector {}", sel);
}
}
HandlerEvent::OnPage => {
props.iter_mut().for_each(|propagator| {
propagator(&HandlerArgs {
page,
element: None,
client: self.client.clone(),
})
.iter()
.filter(|u| {
is_allowed(u, wl, bl) && (revisit || !is_visited(u, &mut visited))
})
.for_each(|u| {
queue.push_back((u.clone(), page.depth + 1));
});
});
}
}
}
Ok(())
}
fn do_handlers(&mut self, page: &Page) -> Result<()> {
for (kind, handlers) in self.handlers.iter_mut() {
match kind {
HandlerEvent::OnSelector(sel) => {
if let Ok(sel) = Selector::parse(sel) {
handlers.iter_mut().for_each(|handler| {
page.doc.select(&sel).for_each(|el| {
handler(&HandlerArgs {
page,
element: Some(el),
client: self.client.clone(),
});
});
});
} else {
bail!("invalid selector {}", sel);
}
}
HandlerEvent::OnPage => {
handlers.iter_mut().for_each(|handler| {
handler(&HandlerArgs {
page,
element: None,
client: self.client.clone(),
});
});
}
}
}
Ok(())
}
/// make a request and send the results on the async chan
async fn fetch(
url: Url,
depth: usize,
client: Arc<Client>,
sender: Sender<Result<(Url, String, usize)>>,
) -> Result<()> {
// Must send a message or die trying
match client.get(url.clone()).send().await {
Ok(res) => match res.text().await {
Ok(text) => {
sender.send(Ok((url, text, depth))).await.unwrap();
Ok(())
}
Err(err) => {
let err = anyhow!(err);
sender.send(Err(err)).await.unwrap();
Err(anyhow!("Failed read"))
}
},
Err(err) => {
let err = anyhow!(err);
sender.send(Err(err)).await.unwrap();
Err(anyhow!("Failed request"))
}
}
}
}