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
use super::File;
use crate::mm::UserBuffer;
use crate::task::suspend_current_and_run_next;
use alloc::sync::{Arc, Weak};
use spin::Mutex;

pub struct Pipe {
    readable: bool,
    writable: bool,
    buffer: Arc<Mutex<PipeRingBuffer>>,
}

impl Pipe {
    pub fn read_end_with_buffer(buffer: Arc<Mutex<PipeRingBuffer>>) -> Self {
        Self {
            readable: true,
            writable: false,
            buffer,
        }
    }
    pub fn write_end_with_buffer(buffer: Arc<Mutex<PipeRingBuffer>>) -> Self {
        Self {
            readable: false,
            writable: true,
            buffer,
        }
    }
}

// const RING_BUFFER_SIZE: usize = 32;
const RING_BUFFER_SIZE: usize = 3010;

#[derive(Copy, Clone, PartialEq)]
enum RingBufferStatus {
    FULL,
    EMPTY,
    NORMAL,
}

pub struct PipeRingBuffer {
    arr: [u8; RING_BUFFER_SIZE],
    head: usize,
    tail: usize,
    status: RingBufferStatus,
    write_end: Option<Weak<Pipe>>,
    read_end: Option<Weak<Pipe>>,
    count: usize,
}

impl PipeRingBuffer {
    pub fn new() -> Self {
        Self {
            arr: [0; RING_BUFFER_SIZE],
            head: 0,
            tail: 0,
            status: RingBufferStatus::EMPTY,
            write_end: None,
            read_end: None,
            count: 0,
        }
    }
    pub fn set_write_end(&mut self, write_end: &Arc<Pipe>) {
        self.write_end = Some(Arc::downgrade(write_end));
    }
    pub fn set_read_end(&mut self, write_end: &Arc<Pipe>) {
        self.read_end = Some(Arc::downgrade(write_end));
    }
    pub fn write_byte(&mut self, byte: u8) {
        self.status = RingBufferStatus::NORMAL;
        self.arr[self.tail] = byte;
        self.tail = (self.tail + 1) % RING_BUFFER_SIZE;
        if self.tail == self.head {
            self.status = RingBufferStatus::FULL;
        }
    }
    pub fn read_byte(&mut self) -> u8 {
        self.status = RingBufferStatus::NORMAL;
        let c = self.arr[self.head];
        self.head = (self.head + 1) % RING_BUFFER_SIZE;
        if self.head == self.tail {
            self.status = RingBufferStatus::EMPTY;
        }
        c
    }
    pub fn available_read(&self) -> usize {
        if self.status == RingBufferStatus::EMPTY {
            0
        } else {
            if self.tail > self.head {
                self.tail - self.head
            } else {
                self.tail + RING_BUFFER_SIZE - self.head
            }
        }
    }
    pub fn available_write(&self) -> usize {
        if self.status == RingBufferStatus::FULL {
            0
        } else {
            RING_BUFFER_SIZE - self.available_read()
        }
    }
    pub fn all_write_ends_closed(&self) -> bool {
        self.write_end.as_ref().unwrap().upgrade().is_none()
    }
    pub fn all_read_ends_closed(&self) -> bool {
        self.read_end.as_ref().unwrap().upgrade().is_none()
    }
}

/// Return (read_end, write_end)
pub fn make_pipe() -> (Arc<Pipe>, Arc<Pipe>) {
    let buffer = Arc::new(Mutex::new(PipeRingBuffer::new()));
    // buffer仅剩两个强引用,这样读写端关闭后就会被释放
    let read_end = Arc::new(Pipe::read_end_with_buffer(buffer.clone()));
    let write_end = Arc::new(Pipe::write_end_with_buffer(buffer.clone()));
    buffer.lock().set_write_end(&write_end);
    buffer.lock().set_read_end(&read_end);
    (read_end, write_end)
}

impl File for Pipe {
    fn readable(&self) -> bool {
        self.readable
    }
    fn writable(&self) -> bool {
        self.writable
    }
    fn hang_up(&self) -> bool {
        // The peer has closed its end.
        // Or maybe you should only check whether both ends have been closed by the peer.
        if self.readable {
            self.buffer.lock().all_write_ends_closed()
        } else {
            //writable
            self.buffer.lock().all_read_ends_closed()
        }
    }
    fn read(&self, buf: UserBuffer) -> usize {
        assert_eq!(self.readable(), true);
        let mut buf_iter = buf.into_iter();
        let mut read_size = 0usize;
        let mut try_time = 0;
        loop {
            let mut ring_buffer = self.buffer.lock();
            let loop_read = ring_buffer.available_read();
            if loop_read == 0 {
                if ring_buffer.all_write_ends_closed() {
                    return read_size; //return后就ring_buffer释放了,锁自然释放
                }
                // gdb_print!(SYSCALL_ENABLE,"[pipe] try read");
                drop(ring_buffer);
                suspend_current_and_run_next();
                continue;
            }
            //gdb_print!(SYSCALL_ENABLE,"[pipe] can read {} bytes\n", loop_read);
            // read at most loop_read bytes
            for i in 0..loop_read {
                if let Some(byte_ref) = buf_iter.next() {
                    unsafe {
                        *byte_ref = ring_buffer.read_byte();
                    }
                    read_size += 1;
                    //panic!("[pipe] read");
                } else {
                    //panic!("[pipe] read");
                    ring_buffer.count += 1;
                    return read_size;
                }
            }
            return read_size;
        }
    }
    fn write(&self, buf: UserBuffer) -> usize {
        //log::info!("[pipe.write] attempt to write...");
        //        log::warn!("[pipe.write] attempted wr");
        assert_eq!(self.writable(), true);
        let mut buf_iter = buf.into_iter();
        let mut write_size = 0usize;
        loop {
            //            log::warn!("[pipe.write]attempted lock");
            let mut ring_buffer = self.buffer.lock();
            //            log::warn!("[pipe.write]attempted lock done.");
            let loop_write = ring_buffer.available_write();
            //            log::warn!("[pipe.write]size avail:{}", loop_write);
            //log::info!("[pipe.write] Lock acquired...");
            if loop_write == 0 {
                drop(ring_buffer);
                // gdb_print!(SYSCALL_ENABLE,"[pipe] try write");

                // if suspend_current_and_run_next() < 0{
                //     return write_size;
                // }
                continue;
            }

            for i in 0..loop_write {
                if let Some(byte_ref) = buf_iter.next() {
                    ring_buffer.write_byte(unsafe { *byte_ref });
                    write_size += 1;
                    ring_buffer.count += 1;
                } else {
                    return write_size;
                }
            }
        }
    }

    fn r_ready(&self) -> bool {
        let ring_buffer = self.buffer.lock();
        let loop_read = ring_buffer.available_read();
        /* log::warn!(
         *     "r_ready: h{},t{},lhd{}",
         *     ring_buffer.head,
         *     ring_buffer.tail,
         *     loop_read
         * ); */
        loop_read > 0
    }

    fn w_ready(&self) -> bool {
        let ring_buffer = self.buffer.lock();
        let loop_write = ring_buffer.available_write();
        /* log::warn!(
         *     "w_ready: h{},t{},lhd{}",
         *     ring_buffer.head,
         *     ring_buffer.tail,
         *     loop_write
         * ); */
        loop_write > 0
    }
}