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
use std::fs::*;
use std::io::{self};
use std::path::{Path, PathBuf};
use crate::header::Header;
use crate::sync::{FileGuard, SyncFollower};
use crate::version::check_queue_version;
use crate::state::{QueueStatePersistence, QueueState};
use super::try_acquire_recv_lock;
use super::{segment_filename, HEADER_EOF};
pub struct QueueIter {
_file_guard: FileGuard,
base: PathBuf,
state: QueueState,
sync_follower: SyncFollower,
}
impl QueueIter {
pub fn open<P: AsRef<Path>>(base: P) -> io::Result<QueueIter> {
create_dir_all(base.as_ref())?;
log::trace!("created queue directory");
check_queue_version(base.as_ref())?;
let file_guard = try_acquire_recv_lock(base.as_ref())?;
let mut persistence = QueueStatePersistence::new();
let state = persistence.open(base.as_ref())?;
log::trace!("receiver lock acquired. Iter state now is {:?}", state);
let mut sync_follower = SyncFollower::open(segment_filename(base.as_ref(), state.segment))?;
sync_follower.seek(io::SeekFrom::Start(state.position))?;
log::trace!("last segment opened fo reading");
Ok(QueueIter {
_file_guard: file_guard,
state,
base: PathBuf::from(base.as_ref()),
sync_follower,
})
}
fn advance_segment(&mut self) -> io::Result<()> {
let current_segment = self.state.segment;
self.state.advance_segment();
let next_segment = self.state.segment;
log::debug!("advanced segment from {:?} to {:?}", current_segment, next_segment);
log::debug!("opening segment {}", next_segment);
self.sync_follower =
SyncFollower::open(segment_filename(&self.base, next_segment))?;
Ok(())
}
fn read_header(&mut self) -> io::Result<Header> {
let mut header = [0; 4];
self.sync_follower.read_exact(&mut header)?;
if header == HEADER_EOF {
log::trace!("got EOF header. Advancing...");
self.advance_segment()?;
log::trace!("re-reading new header from new file");
self.sync_follower.read_exact(&mut header)?;
}
let decoded = Header::decode(header);
log::trace!("got header {:?} (read {} bytes)", header, decoded.len());
Ok(decoded)
}
fn read_one(&mut self) -> io::Result<Vec<u8>> {
let header = self.read_header()?;
let mut data = vec![0; header.len() as usize];
self.sync_follower
.read_exact(&mut data)
.expect("poisoned queue");
Ok(data)
}
}
impl Iterator for QueueIter {
type Item = io::Result<Vec<u8>>;
fn next(&mut self) -> Option<io::Result<Vec<u8>>> {
match self.read_one() {
Ok(item) => Some(Ok(item)),
Err(err) if err.kind() == io::ErrorKind::UnexpectedEof => {
log::trace!("got interrupted by eof");
None
}
Err(err) => Some(Err(err)),
}
}
}