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
use super::*;
pub(crate) struct Context {
// TODO file from config should be in here
config: Config,
pub(crate) pagecache: PageCache<BLinkMaterializer, Frag>,
}
impl std::ops::Deref for Context {
type Target = Config;
fn deref(&self) -> &Config {
&self.config
}
}
impl Drop for Context {
fn drop(&mut self) {
if let Err(e) = self.pagecache.flush() {
error!(
"failed to flush underlying \
pagecache during drop: {:?}",
e
);
}
#[cfg(feature = "event_log")]
{
let tx = Tx::new(0);
self.config.event_log.meta_before_restart(
self.pagecache
.meta(&tx)
.expect("should get meta under test")
.clone(),
);
}
}
}
impl Context {
pub(crate) fn start(config: Config) -> Result<Context> {
#[cfg(any(test, feature = "check_snapshot_integrity"))]
match config.verify_snapshot::<BLinkMaterializer, Frag>() {
Ok(_) => {}
#[cfg(feature = "failpoints")]
Err(Error::FailPoint) => {}
other => panic!("failed to verify snapshot: {:?}", other),
}
let pagecache = PageCache::start(config.clone())?;
Ok(Context { config, pagecache })
}
/// Returns `true` if the database was
/// recovered from a previous process.
/// Note that database state is only
/// guaranteed to be present up to the
/// last call to `flush`! Otherwise state
/// is synced to disk periodically if the
/// `sync_every_ms` configuration option
/// is set to `Some(number_of_ms_between_syncs)`
/// or if the IO buffer gets filled to
/// capacity before being rotated.
pub fn was_recovered(&self) -> bool {
self.pagecache.was_recovered()
}
/// Generate a monotonic ID. Not guaranteed to be
/// contiguous. Written to disk every `idgen_persist_interval`
/// operations, followed by a blocking flush. During recovery, we
/// take the last recovered generated ID and add 2x
/// the `idgen_persist_interval` to it. While persisting, if the
/// previous persisted counter wasn't synced to disk yet, we will do
/// a blocking flush to fsync the latest counter, ensuring
/// that we will never give out the same counter twice.
pub fn generate_id(&self) -> Result<u64> {
self.pagecache.generate_id()
}
}