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annotate rationale on multiple variants of pddb mount calls

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bunnie 2022-04-06 23:46:39 +08:00
parent 1b25f4c11d
commit b75df1efb3
1 changed files with 9 additions and 2 deletions
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11
services/pddb/src/lib.rs
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@ -35,6 +35,11 @@ impl PddbMountPoller {
let conn = xns.request_connection_blocking(api::SERVER_NAME_PDDB_POLLER).expect("can't connect to Pddb mount poller server");
PddbMountPoller { conn }
}
/// This call is guaranteed to *never* block and return the instantaneous state of the PDDB, even if the server itself
/// is currently busy processing other requests. This has to be done with a separate server from the main one, because
/// the main server will block during the mount operations, as it owns the PDDB data objects and cannot concurrently process
/// the mount check task while manipulating them. Instead, this routine queries a separate thread that shares an AtomicBool
/// with the main thread that reports the mount state.
pub fn is_mounted_nonblocking(&self) -> bool {
match send_message(self.conn,
Message::new_blocking_scalar(PollOp::Poll.to_usize().unwrap(), 0, 0, 0, 0)
@ -125,7 +130,9 @@ impl Pddb {
tt: ticktimer_server::Ticktimer::new().unwrap(),
}
}
pub fn is_mounted(&self) -> bool {
/// This call "sometimes blocks". It will block when the PDDB is busy performing other tasks, such as
/// mounting the PDDB, or requesting the user's password.
pub fn is_mounted_maybe_blocking(&self) -> bool {
let ret = send_message(self.conn, Message::new_blocking_scalar(
Opcode::IsMounted.to_usize().unwrap(), 0, 0, 0, 0)).expect("couldn't execute IsMounted query");
match ret {
@ -144,7 +151,7 @@ impl Pddb {
} else {
(self.trng.get_u32().unwrap() % 1000) + 1000
};
while !self.is_mounted() {
while !self.is_mounted_maybe_blocking() {
self.tt.sleep_ms(interval as usize).unwrap();
}
}