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
use crate::{protocols::ReturnableConnection, Pea2Pea};
use async_trait::async_trait;
use parking_lot::RwLock;
use tokio::{
io::{AsyncWrite, AsyncWriteExt},
sync::mpsc,
};
use tracing::*;
use std::{any::Any, collections::HashMap, io, net::SocketAddr};
/// Can be used to specify and enable writing, i.e. sending outbound messages. If the `Handshake`
/// protocol is enabled too, it goes into force only after the handshake has been concluded.
#[async_trait]
pub trait Writing: Pea2Pea
where
Self: Clone + Send + Sync + 'static,
{
/// The type of the outbound messages; unless their serialization is expensive and the message
/// is broadcasted (in which case it would get serialized multiple times), serialization should
/// be done in `Writing::write_message`.
type Message: Send;
/// Prepares the node to send messages.
fn enable_writing(&self) {
let (conn_sender, mut conn_receiver) = mpsc::channel::<ReturnableConnection>(
self.node().config().protocol_handler_queue_depth,
);
// the task spawning tasks reading messages from the given stream
let self_clone = self.clone();
let writing_task = tokio::spawn(async move {
trace!(parent: self_clone.node().span(), "spawned the Writing handler task");
// these objects are sent from `Node::adapt_stream`
while let Some((mut conn, conn_returner)) = conn_receiver.recv().await {
let addr = conn.addr;
let mut writer = conn.writer.take().unwrap(); // safe; it is available at this point
let mut buffer = Vec::new();
let (outbound_message_sender, mut outbound_message_receiver) =
mpsc::channel(self_clone.node().config().outbound_queue_depth);
if let Some(handler) = self_clone.node().protocols.writing_handler.get() {
handler
.senders
.write()
.insert(addr, outbound_message_sender);
} else {
unreachable!();
}
// the task for writing outbound messages
let writer_clone = self_clone.clone();
let writer_task = tokio::spawn(async move {
let node = writer_clone.node();
trace!(parent: node.span(), "spawned a task for writing messages to {}", addr);
// TODO: when try_recv is available in tokio again (https://github.com/tokio-rs/tokio/issues/3350),
// use try_recv() in order to write to the stream less often
while let Some(msg) = outbound_message_receiver.recv().await {
let msg = msg.downcast::<Self::Message>().unwrap();
match writer_clone
.write_to_stream(*msg, addr, &mut buffer, &mut writer)
.await
{
Ok(len) => {
node.known_peers().register_sent_message(addr, len);
node.stats().register_sent_message(len);
trace!(parent: node.span(), "sent {}B to {}", len, addr);
}
Err(e) => {
node.known_peers().register_failure(addr);
error!(parent: node.span(), "couldn't send a message to {}: {}", addr, e);
if node.config().fatal_io_errors.contains(&e.kind()) {
node.disconnect(addr).await;
break;
}
}
}
}
});
conn.tasks.push(writer_task);
// return the Connection to the Node, resuming Node::adapt_stream
if conn_returner.send(Ok(conn)).is_err() {
unreachable!("could't return a Connection to the Node");
}
}
});
self.node().tasks.lock().push(writing_task);
// register the WritingHandler with the Node
let hdl = WritingHandler {
handler: conn_sender,
senders: Default::default(),
};
if self.node().protocols.writing_handler.set(hdl).is_err() {
panic!("the Writing protocol was enabled more than once!");
}
}
/// Writes the given message to the provided writer, using the provided intermediate buffer; returns the number of
/// bytes written to the writer.
async fn write_to_stream<W: AsyncWrite + Unpin + Send>(
&self,
message: Self::Message,
addr: SocketAddr,
buffer: &mut Vec<u8>,
writer: &mut W,
) -> io::Result<usize> {
self.write_message(addr, &message, buffer)?;
let len = buffer.len();
writer.write_all(buffer).await?;
buffer.clear();
Ok(len)
}
/// Writes the provided payload to the given intermediate writer; the payload can get prepended with a header
/// indicating its length, be suffixed with a character indicating that it's complete, etc. Returns the number
/// of bytes written to the writer.
fn write_message<W: io::Write>(
&self,
target: SocketAddr,
message: &Self::Message,
writer: &mut W,
) -> io::Result<()>;
/// Sends the provided message to the specified `SocketAddr`.
fn send_direct_message(&self, addr: SocketAddr, message: Self::Message) -> io::Result<()> {
if let Some(sender) = self
.node()
.protocols
.writing_handler
.get()
.and_then(|h| h.senders.read().get(&addr).cloned())
{
sender.try_send(Box::new(message)).map_err(|e| {
error!(parent: self.node().span(), "can't send a message to {}: {}", addr, e);
self.node().stats().register_failure();
io::ErrorKind::Other.into()
})
} else {
Err(io::ErrorKind::Unsupported.into())
}
}
/// Broadcasts the provided message to all peers.
fn send_broadcast(&self, message: Self::Message)
where
Self::Message: Clone,
{
if let Some(handler) = self.node().protocols.writing_handler.get() {
let senders = handler.senders.read().clone();
for (addr, message_sender) in senders {
let _ = message_sender.try_send(Box::new(message.clone())).map_err(|e| {
error!(parent: self.node().span(), "can't send a message to {}: {}", addr, e);
self.node().stats().register_failure();
});
}
}
}
}
/// The handler object dedicated to the `Writing` protocol.
pub struct WritingHandler {
handler: mpsc::Sender<ReturnableConnection>,
pub(crate) senders: RwLock<HashMap<SocketAddr, mpsc::Sender<Box<dyn Any + Send>>>>,
}
impl WritingHandler {
pub(crate) async fn trigger(&self, item: ReturnableConnection) {
if self.handler.send(item).await.is_err() {
unreachable!(); // protocol's task is down! can't recover
}
}
}