Files
aho_corasick
arrayvec
base64
bech32
bitcoin
bitcoin_hashes
bitcoin_rest
bitcoincore_rpc
bitcoincore_rpc_json
bitflags
block_buffer
byteorder
bytes
cfg_if
chainseeker
chainseeker_server
cpufeatures
crossbeam_channel
crossbeam_deque
crossbeam_epoch
crossbeam_utils
digest
either
encoding_rs
fnv
foreign_types
foreign_types_shared
form_urlencoded
futures_channel
futures_core
futures_io
futures_macro
futures_sink
futures_task
futures_util
async_await
future
io
lock
sink
stream
task
generic_array
getrandom
h2
hashbrown
hex
http
http_body
httparse
httpdate
hyper
hyper_tls
idna
indexmap
input_buffer
ipnet
itoa
jsonrpc
lazy_static
libc
librocksdb_sys
log
matches
memchr
memoffset
mime
mio
native_tls
nodrop
num_cpus
num_format
once_cell
opaque_debug
openssl
openssl_probe
openssl_sys
percent_encoding
pin_project
pin_project_internal
pin_project_lite
pin_utils
ppv_lite86
proc_macro2
proc_macro_hack
proc_macro_nested
quote
rand
rand_chacha
rand_core
rayon
rayon_core
regex
regex_syntax
reqwest
rocksdb
routerify
ryu
scopeguard
secp256k1
secp256k1_sys
serde
serde_derive
serde_json
serde_urlencoded
sha1
signal_hook_registry
slab
socket2
syn
thiserror
thiserror_impl
tinyvec
tinyvec_macros
tokio
future
io
loom
macros
net
park
runtime
signal
sync
task
time
util
tokio_macros
tokio_native_tls
tokio_tungstenite
tokio_util
toml
tower_service
tracing
tracing_core
try_lock
tungstenite
typenum
unicode_bidi
unicode_normalization
unicode_xid
url
utf8
want
zmq
zmq_sys
  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
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
//! In-process memory IO types.

use crate::io::{AsyncRead, AsyncWrite, ReadBuf};
use crate::loom::sync::Mutex;

use bytes::{Buf, BytesMut};
use std::{
    pin::Pin,
    sync::Arc,
    task::{self, Poll, Waker},
};

/// A bidirectional pipe to read and write bytes in memory.
///
/// A pair of `DuplexStream`s are created together, and they act as a "channel"
/// that can be used as in-memory IO types. Writing to one of the pairs will
/// allow that data to be read from the other, and vice versa.
///
/// # Closing a `DuplexStream`
///
/// If one end of the `DuplexStream` channel is dropped, any pending reads on
/// the other side will continue to read data until the buffer is drained, then
/// they will signal EOF by returning 0 bytes. Any writes to the other side,
/// including pending ones (that are waiting for free space in the buffer) will
/// return `Err(BrokenPipe)` immediately.
///
/// # Example
///
/// ```
/// # async fn ex() -> std::io::Result<()> {
/// # use tokio::io::{AsyncReadExt, AsyncWriteExt};
/// let (mut client, mut server) = tokio::io::duplex(64);
///
/// client.write_all(b"ping").await?;
///
/// let mut buf = [0u8; 4];
/// server.read_exact(&mut buf).await?;
/// assert_eq!(&buf, b"ping");
///
/// server.write_all(b"pong").await?;
///
/// client.read_exact(&mut buf).await?;
/// assert_eq!(&buf, b"pong");
/// # Ok(())
/// # }
/// ```
#[derive(Debug)]
#[cfg_attr(docsrs, doc(cfg(feature = "io-util")))]
pub struct DuplexStream {
    read: Arc<Mutex<Pipe>>,
    write: Arc<Mutex<Pipe>>,
}

/// A unidirectional IO over a piece of memory.
///
/// Data can be written to the pipe, and reading will return that data.
#[derive(Debug)]
struct Pipe {
    /// The buffer storing the bytes written, also read from.
    ///
    /// Using a `BytesMut` because it has efficient `Buf` and `BufMut`
    /// functionality already. Additionally, it can try to copy data in the
    /// same buffer if there read index has advanced far enough.
    buffer: BytesMut,
    /// Determines if the write side has been closed.
    is_closed: bool,
    /// The maximum amount of bytes that can be written before returning
    /// `Poll::Pending`.
    max_buf_size: usize,
    /// If the `read` side has been polled and is pending, this is the waker
    /// for that parked task.
    read_waker: Option<Waker>,
    /// If the `write` side has filled the `max_buf_size` and returned
    /// `Poll::Pending`, this is the waker for that parked task.
    write_waker: Option<Waker>,
}

// ===== impl DuplexStream =====

/// Create a new pair of `DuplexStream`s that act like a pair of connected sockets.
///
/// The `max_buf_size` argument is the maximum amount of bytes that can be
/// written to a side before the write returns `Poll::Pending`.
#[cfg_attr(docsrs, doc(cfg(feature = "io-util")))]
pub fn duplex(max_buf_size: usize) -> (DuplexStream, DuplexStream) {
    let one = Arc::new(Mutex::new(Pipe::new(max_buf_size)));
    let two = Arc::new(Mutex::new(Pipe::new(max_buf_size)));

    (
        DuplexStream {
            read: one.clone(),
            write: two.clone(),
        },
        DuplexStream {
            read: two,
            write: one,
        },
    )
}

impl AsyncRead for DuplexStream {
    // Previous rustc required this `self` to be `mut`, even though newer
    // versions recognize it isn't needed to call `lock()`. So for
    // compatibility, we include the `mut` and `allow` the lint.
    //
    // See https://github.com/rust-lang/rust/issues/73592
    #[allow(unused_mut)]
    fn poll_read(
        mut self: Pin<&mut Self>,
        cx: &mut task::Context<'_>,
        buf: &mut ReadBuf<'_>,
    ) -> Poll<std::io::Result<()>> {
        Pin::new(&mut *self.read.lock()).poll_read(cx, buf)
    }
}

impl AsyncWrite for DuplexStream {
    #[allow(unused_mut)]
    fn poll_write(
        mut self: Pin<&mut Self>,
        cx: &mut task::Context<'_>,
        buf: &[u8],
    ) -> Poll<std::io::Result<usize>> {
        Pin::new(&mut *self.write.lock()).poll_write(cx, buf)
    }

    #[allow(unused_mut)]
    fn poll_flush(
        mut self: Pin<&mut Self>,
        cx: &mut task::Context<'_>,
    ) -> Poll<std::io::Result<()>> {
        Pin::new(&mut *self.write.lock()).poll_flush(cx)
    }

    #[allow(unused_mut)]
    fn poll_shutdown(
        mut self: Pin<&mut Self>,
        cx: &mut task::Context<'_>,
    ) -> Poll<std::io::Result<()>> {
        Pin::new(&mut *self.write.lock()).poll_shutdown(cx)
    }
}

impl Drop for DuplexStream {
    fn drop(&mut self) {
        // notify the other side of the closure
        self.write.lock().close_write();
        self.read.lock().close_read();
    }
}

// ===== impl Pipe =====

impl Pipe {
    fn new(max_buf_size: usize) -> Self {
        Pipe {
            buffer: BytesMut::new(),
            is_closed: false,
            max_buf_size,
            read_waker: None,
            write_waker: None,
        }
    }

    fn close_write(&mut self) {
        self.is_closed = true;
        // needs to notify any readers that no more data will come
        if let Some(waker) = self.read_waker.take() {
            waker.wake();
        }
    }

    fn close_read(&mut self) {
        self.is_closed = true;
        // needs to notify any writers that they have to abort
        if let Some(waker) = self.write_waker.take() {
            waker.wake();
        }
    }
}

impl AsyncRead for Pipe {
    fn poll_read(
        mut self: Pin<&mut Self>,
        cx: &mut task::Context<'_>,
        buf: &mut ReadBuf<'_>,
    ) -> Poll<std::io::Result<()>> {
        if self.buffer.has_remaining() {
            let max = self.buffer.remaining().min(buf.remaining());
            buf.put_slice(&self.buffer[..max]);
            self.buffer.advance(max);
            if max > 0 {
                // The passed `buf` might have been empty, don't wake up if
                // no bytes have been moved.
                if let Some(waker) = self.write_waker.take() {
                    waker.wake();
                }
            }
            Poll::Ready(Ok(()))
        } else if self.is_closed {
            Poll::Ready(Ok(()))
        } else {
            self.read_waker = Some(cx.waker().clone());
            Poll::Pending
        }
    }
}

impl AsyncWrite for Pipe {
    fn poll_write(
        mut self: Pin<&mut Self>,
        cx: &mut task::Context<'_>,
        buf: &[u8],
    ) -> Poll<std::io::Result<usize>> {
        if self.is_closed {
            return Poll::Ready(Err(std::io::ErrorKind::BrokenPipe.into()));
        }
        let avail = self.max_buf_size - self.buffer.len();
        if avail == 0 {
            self.write_waker = Some(cx.waker().clone());
            return Poll::Pending;
        }

        let len = buf.len().min(avail);
        self.buffer.extend_from_slice(&buf[..len]);
        if let Some(waker) = self.read_waker.take() {
            waker.wake();
        }
        Poll::Ready(Ok(len))
    }

    fn poll_flush(self: Pin<&mut Self>, _: &mut task::Context<'_>) -> Poll<std::io::Result<()>> {
        Poll::Ready(Ok(()))
    }

    fn poll_shutdown(
        mut self: Pin<&mut Self>,
        _: &mut task::Context<'_>,
    ) -> Poll<std::io::Result<()>> {
        self.close_write();
        Poll::Ready(Ok(()))
    }
}