script/
document_loader.rs

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
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

//! Tracking of pending loads in a document.
//!
//! <https://html.spec.whatwg.org/multipage/#the-end>

use net_traits::request::RequestBuilder;
use net_traits::{fetch_async, BoxedFetchCallback, ResourceThreads};
use servo_url::ServoUrl;

use crate::dom::bindings::cell::DomRefCell;
use crate::dom::bindings::root::Dom;
use crate::dom::document::Document;
use crate::fetch::FetchCanceller;
use crate::script_runtime::CanGc;

#[derive(Clone, Debug, JSTraceable, MallocSizeOf, PartialEq)]
pub(crate) enum LoadType {
    Image(#[no_trace] ServoUrl),
    Script(#[no_trace] ServoUrl),
    Subframe(#[no_trace] ServoUrl),
    Stylesheet(#[no_trace] ServoUrl),
    PageSource(#[no_trace] ServoUrl),
    Media,
}

/// Canary value ensuring that manually added blocking loads (ie. ones that weren't
/// created via DocumentLoader::fetch_async) are always removed by the time
/// that the owner is destroyed.
#[derive(JSTraceable, MallocSizeOf)]
#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
pub(crate) struct LoadBlocker {
    /// The document whose load event is blocked by this object existing.
    doc: Dom<Document>,
    /// The load that is blocking the document's load event.
    load: Option<LoadType>,
}

impl LoadBlocker {
    /// Mark the document's load event as blocked on this new load.
    pub(crate) fn new(doc: &Document, load: LoadType) -> LoadBlocker {
        doc.loader_mut().add_blocking_load(load.clone());
        LoadBlocker {
            doc: Dom::from_ref(doc),
            load: Some(load),
        }
    }

    /// Remove this load from the associated document's list of blocking loads.
    pub(crate) fn terminate(blocker: &DomRefCell<Option<LoadBlocker>>, can_gc: CanGc) {
        if let Some(this) = blocker.borrow().as_ref() {
            let load_data = this.load.clone().unwrap();
            this.doc.finish_load(load_data, can_gc);
        }
        *blocker.borrow_mut() = None;
    }
}

impl Drop for LoadBlocker {
    fn drop(&mut self) {
        if let Some(load) = self.load.take() {
            self.doc.finish_load(load, CanGc::note());
        }
    }
}

#[derive(JSTraceable, MallocSizeOf)]
pub(crate) struct DocumentLoader {
    #[no_trace]
    resource_threads: ResourceThreads,
    blocking_loads: Vec<LoadType>,
    events_inhibited: bool,
    cancellers: Vec<FetchCanceller>,
}

impl DocumentLoader {
    pub(crate) fn new(existing: &DocumentLoader) -> DocumentLoader {
        DocumentLoader::new_with_threads(existing.resource_threads.clone(), None)
    }

    pub(crate) fn new_with_threads(
        resource_threads: ResourceThreads,
        initial_load: Option<ServoUrl>,
    ) -> DocumentLoader {
        debug!("Initial blocking load {:?}.", initial_load);
        let initial_loads = initial_load.into_iter().map(LoadType::PageSource).collect();

        DocumentLoader {
            resource_threads,
            blocking_loads: initial_loads,
            events_inhibited: false,
            cancellers: Vec::new(),
        }
    }

    pub(crate) fn cancel_all_loads(&mut self) -> bool {
        let canceled_any = !self.cancellers.is_empty();
        // Associated fetches will be canceled when dropping the canceller.
        self.cancellers.clear();
        canceled_any
    }

    /// Add a load to the list of blocking loads.
    fn add_blocking_load(&mut self, load: LoadType) {
        debug!(
            "Adding blocking load {:?} ({}).",
            load,
            self.blocking_loads.len()
        );
        self.blocking_loads.push(load);
    }

    /// Initiate a new fetch given a response callback.
    pub(crate) fn fetch_async_with_callback(
        &mut self,
        load: LoadType,
        request: RequestBuilder,
        callback: BoxedFetchCallback,
    ) {
        self.add_blocking_load(load);
        self.fetch_async_background(request, callback);
    }

    /// Initiate a new fetch that does not block the document load event.
    pub(crate) fn fetch_async_background(
        &mut self,
        request: RequestBuilder,
        callback: BoxedFetchCallback,
    ) {
        self.cancellers.push(FetchCanceller::new(request.id));
        fetch_async(&self.resource_threads.core_thread, request, None, callback);
    }

    /// Mark an in-progress network request complete.
    pub(crate) fn finish_load(&mut self, load: &LoadType) {
        debug!(
            "Removing blocking load {:?} ({}).",
            load,
            self.blocking_loads.len()
        );
        let idx = self
            .blocking_loads
            .iter()
            .position(|unfinished| *unfinished == *load);
        match idx {
            Some(i) => {
                self.blocking_loads.remove(i);
            },
            None => warn!("unknown completed load {:?}", load),
        }
    }

    pub(crate) fn is_blocked(&self) -> bool {
        // TODO: Ensure that we report blocked if parsing is still ongoing.
        !self.blocking_loads.is_empty()
    }

    pub(crate) fn is_only_blocked_by_iframes(&self) -> bool {
        self.blocking_loads
            .iter()
            .all(|load| matches!(*load, LoadType::Subframe(_)))
    }

    pub(crate) fn inhibit_events(&mut self) {
        self.events_inhibited = true;
    }

    pub(crate) fn events_inhibited(&self) -> bool {
        self.events_inhibited
    }

    pub(crate) fn resource_threads(&self) -> &ResourceThreads {
        &self.resource_threads
    }
}