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Small API Improvements #102

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merged 5 commits into from
Aug 22, 2018
Merged

Small API Improvements #102

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bda8acc
Use impl trait in progress
Aug 8, 2018
1676ccd
Make ProgressSet not panic.
Aug 8, 2018
50d80cb
clippy/fmt run
Aug 8, 2018
fca5a21
Reflect comment on checks in promote_learner
Aug 15, 2018
b0004c2
Satisfy clippy
Aug 15, 2018
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9 changes: 8 additions & 1 deletion src/errors.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,14 @@ quick_error! {
description(err.description())
display("protobuf error {:?}", err)
}

/// The node exists, but should not.
Exists(id: u64, set: &'static str) {
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Can these two errors be merged?

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Hm, maybe? I think Exists(u64, &'static str, bool) could work? I worry that there might be some semantic issues. I was already not sure about combining things like VoterCannotBecomeLearner, VoterExists, LearnerExists, and LearnerAlreadyVoter.

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I think distinguishing them may be more clear.

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I don't think so. People usually don't care about what the exact case are they, what they do is just panic. More errors lead to longer match or repeated duplicated error1 | error 2.

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@BusyJay In the case of this particular error there are definitely recoverable cases, and they are different between the errors.

If the user is lazy and wants to panic, that's fine, but we should allow our users to write good code.

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I am fine with this, like Rust IO error, it has NotFound or AlreadyExists error for a file.

LGTM

display("The node {} aleady exists in the {} set.", id, set)
}
/// The node does not exist, but should.
NotExists(id: u64, set: &'static str) {
display("The node {} is not in the {} set.", id, set)
}
}
}

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24 changes: 12 additions & 12 deletions src/log_unstable.rs
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Expand Up @@ -217,8 +217,8 @@ mod test {
for (entries, offset, snapshot, wok, windex) in tests {
let u = Unstable {
entries: entries.map_or(vec![], |entry| vec![entry]),
offset: offset,
snapshot: snapshot,
offset,
snapshot,
..Default::default()
};
let index = u.maybe_first_index();
Expand All @@ -244,8 +244,8 @@ mod test {
for (entries, offset, snapshot, wok, windex) in tests {
let u = Unstable {
entries: entries.map_or(vec![], |entry| vec![entry]),
offset: offset,
snapshot: snapshot,
offset,
snapshot,
..Default::default()
};
let index = u.maybe_last_index();
Expand Down Expand Up @@ -305,8 +305,8 @@ mod test {
for (entries, offset, snapshot, index, wok, wterm) in tests {
let u = Unstable {
entries: entries.map_or(vec![], |entry| vec![entry]),
offset: offset,
snapshot: snapshot,
offset,
snapshot,
..Default::default()
};
let term = u.maybe_term(index);
Expand Down Expand Up @@ -402,9 +402,9 @@ mod test {

for (entries, offset, snapshot, index, term, woffset, wlen) in tests {
let mut u = Unstable {
entries: entries,
offset: offset,
snapshot: snapshot,
entries,
offset,
snapshot,
..Default::default()
};
u.stable_to(index, term);
Expand Down Expand Up @@ -469,9 +469,9 @@ mod test {

for (entries, offset, snapshot, to_append, woffset, wentries) in tests {
let mut u = Unstable {
entries: entries,
offset: offset,
snapshot: snapshot,
entries,
offset,
snapshot,
..Default::default()
};
u.truncate_and_append(&to_append);
Expand Down
60 changes: 29 additions & 31 deletions src/progress.rs
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Expand Up @@ -25,10 +25,10 @@
// See the License for the specific language governing permissions and
// limitations under the License.

use errors::Error;
use fxhash::FxHashMap;
use std::cmp;
use std::collections::hash_map::{HashMap, Iter, IterMut};
use std::iter::Chain;
use std::collections::hash_map::HashMap;

/// The state of the progress.
#[derive(Debug, PartialEq, Clone, Copy)]
Expand Down Expand Up @@ -105,41 +105,37 @@ impl ProgressSet {
}

/// Returns an iterator across all the nodes and their progress.
pub fn iter(&self) -> Chain<Iter<u64, Progress>, Iter<u64, Progress>> {
pub fn iter(&self) -> impl Iterator<Item = (&u64, &Progress)> {
self.voters.iter().chain(&self.learners)
}

/// Returns a mutable iterator across all the nodes and their progress.
pub fn iter_mut(&mut self) -> Chain<IterMut<u64, Progress>, IterMut<u64, Progress>> {
pub fn iter_mut(&mut self) -> impl Iterator<Item = (&u64, &mut Progress)> {
self.voters.iter_mut().chain(&mut self.learners)
}

/// Adds a voter node
///
/// # Panics
///
/// Panics if the node already has been added.
pub fn insert_voter(&mut self, id: u64, pr: Progress) {
if self.learners.contains_key(&id) {
panic!("insert voter {} but already in learners", id);
pub fn insert_voter(&mut self, id: u64, pr: Progress) -> Result<(), Error> {
if self.voters.contains_key(&id) {
Err(Error::Exists(id, "voters"))?
}
if self.voters.insert(id, pr).is_some() {
panic!("insert voter {} twice", id);
if self.learners.contains_key(&id) {
Err(Error::Exists(id, "learners"))?;
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any different to panic outside?

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The error message will be different now. Otherwise this is just moving the error up a level so these functions can be called without worrying about panic.

}
self.voters.insert(id, pr);
Ok(())
}

/// Adds a learner to the cluster
///
/// # Panics
///
/// Panics if the node already has been added.
pub fn insert_learner(&mut self, id: u64, pr: Progress) {
pub fn insert_learner(&mut self, id: u64, pr: Progress) -> Result<(), Error> {
if self.voters.contains_key(&id) {
panic!("insert learner {} but already in voters", id);
Err(Error::Exists(id, "voters"))?
}
if self.learners.insert(id, pr).is_some() {
panic!("insert learner {} twice", id);
if self.learners.contains_key(&id) {
Err(Error::Exists(id, "learners"))?
}
self.learners.insert(id, pr);
Ok(())
}

/// Removes the peer from the set of voters or learners.
Expand All @@ -151,17 +147,19 @@ impl ProgressSet {
}

/// Promote a learner to a peer.
///
/// # Panics
///
/// Panics if the node doesn't exist.
pub fn promote_learner(&mut self, id: u64) {
if let Some(mut pr) = self.learners.remove(&id) {
pr.is_learner = false;
self.voters.insert(id, pr);
return;
pub fn promote_learner(&mut self, id: u64) -> Result<(), Error> {
if self.voters.contains_key(&id) {
Err(Error::Exists(id, "voters"))?;
}
// We don't want to remove it unless it's there.
if self.learners.contains_key(&id) {
let mut learner = self.learners.remove(&id).unwrap(); // We just checked!
learner.is_learner = false;
self.voters.insert(id, learner);
Ok(())
} else {
Err(Error::NotExists(id, "learners"))
}
panic!("promote not exists learner: {}", id);
}
}

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20 changes: 14 additions & 6 deletions src/raft.rs
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Expand Up @@ -263,12 +263,16 @@ impl<T: Storage> Raft<T> {
};
for p in peers {
let pr = new_progress(1, r.max_inflight);
r.mut_prs().insert_voter(*p, pr);
if let Err(e) = r.mut_prs().insert_voter(*p, pr) {
panic!("{}", e);
}
}
for p in learners {
let mut pr = new_progress(1, r.max_inflight);
pr.is_learner = true;
r.mut_prs().insert_learner(*p, pr);
if let Err(e) = r.mut_prs().insert_learner(*p, pr) {
panic!("{}", e);
};
if *p == r.id {
r.is_learner = true;
}
Expand Down Expand Up @@ -1852,7 +1856,9 @@ impl<T: Storage> Raft<T> {
// Ignore redundant add learner.
return;
}
self.mut_prs().promote_learner(id);
if let Err(e) = self.mut_prs().promote_learner(id) {
panic!("{}", e)
}
if id == self.id {
self.is_learner = false;
}
Expand Down Expand Up @@ -1903,9 +1909,11 @@ impl<T: Storage> Raft<T> {
p.matched = matched;
p.is_learner = is_learner;
if is_learner {
self.mut_prs().insert_learner(id, p);
} else {
self.mut_prs().insert_voter(id, p);
if let Err(e) = self.mut_prs().insert_learner(id, p) {
panic!("{}", e);
}
} else if let Err(e) = self.mut_prs().insert_voter(id, p) {
panic!("{}", e);
}
}

Expand Down
2 changes: 1 addition & 1 deletion src/storage.rs
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Expand Up @@ -200,7 +200,7 @@ impl MemStorageCore {
// truncate compacted entries
let te: &[Entry] = if first > ents[0].get_index() {
let start_ent = (first - ents[0].get_index()) as usize;
&ents[start_ent..ents.len()]
&ents[start_ent..]
} else {
ents
};
Expand Down
8 changes: 6 additions & 2 deletions tests/cases/test_raft.rs
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Expand Up @@ -209,12 +209,16 @@ impl Interface {
is_learner: true,
..Default::default()
};
self.mut_prs().insert_learner(*id, progress);
if let Err(e) = self.mut_prs().insert_learner(*id, progress) {
panic!("{}", e);
}
} else {
let progress = Progress {
..Default::default()
};
self.mut_prs().insert_voter(*id, progress);
if let Err(e) = self.mut_prs().insert_voter(*id, progress) {
panic!("{}", e);
}
}
}
let term = self.term;
Expand Down