use std::collections::HashMap;
use std::ops::Deref;
use std::sync::atomic::{AtomicUsize, Ordering};
use serde::{Deserialize, Serialize};
use garage_util::data::*;
use super::*;
use crate::replication_mode::ReplicationMode;
#[derive(Debug, Clone, Serialize, Deserialize, Default, PartialEq, Eq)]
pub struct LayoutDigest {
/// Cluster layout version
pub current_version: u64,
/// Number of active layout versions
pub active_versions: usize,
/// Hash of cluster layout update trackers
pub trackers_hash: Hash,
/// Hash of cluster layout staging data
pub staging_hash: Hash,
}
pub struct LayoutHelper {
replication_mode: ReplicationMode,
layout: Option<LayoutHistory>,
// cached values
ack_map_min: u64,
sync_map_min: u64,
all_nodes: Vec<Uuid>,
all_nongateway_nodes: Vec<Uuid>,
trackers_hash: Hash,
staging_hash: Hash,
// ack lock: counts in-progress write operations for each
// layout version ; we don't increase the ack update tracker
// while this lock is nonzero
pub(crate) ack_lock: HashMap<u64, AtomicUsize>,
}
impl Deref for LayoutHelper {
type Target = LayoutHistory;
fn deref(&self) -> &LayoutHistory {
self.layout()
}
}
impl LayoutHelper {
pub fn new(
replication_mode: ReplicationMode,
mut layout: LayoutHistory,
mut ack_lock: HashMap<u64, AtomicUsize>,
) -> Self {
// In the new() function of the helper, we do a bunch of cleanup
// and calculations on the layout history to make sure things are
// correct and we have rapid access to important values such as
// the layout versions to use when reading to ensure consistency.
if !replication_mode.is_read_after_write_consistent() {
// Fast path for when no consistency is required.
// In this case we only need to keep the last version of the layout,
// we don't care about coordinating stuff in the cluster.
layout.keep_current_version_only();
}
layout.cleanup_old_versions();
let all_nodes = layout.get_all_nodes();
let all_nongateway_nodes = layout.get_all_nongateway_nodes();
layout.clamp_update_trackers(&all_nodes);
let min_version = layout.min_stored();
// ack_map_min is the minimum value of ack_map among all nodes
// in the cluster (gateway, non-gateway, current and previous layouts).
// It is the highest layout version which all of these nodes have
// acknowledged, indicating that they are aware of it and are no
// longer processing write operations that did not take it into account.
let ack_map_min = layout
.update_trackers
.ack_map
.min_among(&all_nodes, min_version);
// sync_map_min is the minimum value of sync_map among storage nodes
// in the cluster (non-gateway nodes only, current and previous layouts).
// It is the highest layout version for which we know that all relevant
// storage nodes have fullfilled a sync, and therefore it is safe to
// use a read quorum within that layout to ensure consistency.
// Gateway nodes are excluded here because they hold no relevant data
// (they store the bucket and access key tables, but we don't have
// consistency on those).
// This value is calculated using quorums to allow progress even
// if not all nodes have successfully completed a sync.
let sync_map_min =
layout.calculate_sync_map_min_with_quorum(replication_mode, &all_nongateway_nodes);
let trackers_hash = layout.calculate_trackers_hash();
let staging_hash = layout.calculate_staging_hash();
ack_lock.retain(|_, cnt| *cnt.get_mut() > 0);
ack_lock
.entry(layout.current().version)
.or_insert(AtomicUsize::new(0));
LayoutHelper {
replication_mode,
layout: Some(layout),
ack_map_min,
sync_map_min,
all_nodes,
all_nongateway_nodes,
trackers_hash,
staging_hash,
ack_lock,
}
}
// ------------------ single updating function --------------
fn layout(&self) -> &LayoutHistory {
self.layout.as_ref().unwrap()
}
pub(crate) fn update<F>(&mut self, f: F) -> bool
where
F: FnOnce(&mut LayoutHistory) -> bool,
{
let changed = f(self.layout.as_mut().unwrap());
if changed {
*self = Self::new(
self.replication_mode,
self.layout.take().unwrap(),
std::mem::take(&mut self.ack_lock),
);
}
changed
}
// ------------------ read helpers ---------------
pub fn all_nodes(&self) -> &[Uuid] {
&self.all_nodes
}
pub fn all_nongateway_nodes(&self) -> &[Uuid] {
&self.all_nongateway_nodes
}
pub fn all_ack(&self) -> u64 {
self.ack_map_min
}
pub fn all_sync(&self) -> u64 {
self.sync_map_min
}
pub fn sync_versions(&self) -> (u64, u64, u64) {
(
self.layout().current().version,
self.all_ack(),
self.layout().min_stored(),
)
}
pub fn read_nodes_of(&self, position: &Hash) -> Vec<Uuid> {
let sync_min = self.sync_map_min;
let version = self
.layout()
.versions
.iter()
.find(|x| x.version == sync_min)
.or(self.layout().versions.last())
.unwrap();
version
.nodes_of(position, version.replication_factor)
.collect()
}
pub fn storage_sets_of(&self, position: &Hash) -> Vec<Vec<Uuid>> {
self.layout()
.versions
.iter()
.map(|x| x.nodes_of(position, x.replication_factor).collect())
.collect()
}
pub fn storage_nodes_of(&self, position: &Hash) -> Vec<Uuid> {
let mut ret = vec![];
for version in self.layout().versions.iter() {
ret.extend(version.nodes_of(position, version.replication_factor));
}
ret.sort();
ret.dedup();
ret
}
pub fn trackers_hash(&self) -> Hash {
self.trackers_hash
}
pub fn staging_hash(&self) -> Hash {
self.staging_hash
}
pub fn digest(&self) -> LayoutDigest {
LayoutDigest {
current_version: self.current().version,
active_versions: self.versions.len(),
trackers_hash: self.trackers_hash,
staging_hash: self.staging_hash,
}
}
// ------------------ helpers for update tracking ---------------
pub(crate) fn update_trackers(&mut self, local_node_id: Uuid) {
// Ensure trackers for this node's values are up-to-date
// 1. Acknowledge the last layout version which is not currently
// locked by an in-progress write operation
self.ack_max_free(local_node_id);
// 2. Assume the data on this node is sync'ed up at least to
// the first layout version in the history
self.sync_first(local_node_id);
// 3. Acknowledge everyone has synced up to min(self.sync_map)
self.sync_ack(local_node_id);
info!("ack_map: {:?}", self.update_trackers.ack_map);
info!("sync_map: {:?}", self.update_trackers.sync_map);
info!("sync_ack_map: {:?}", self.update_trackers.sync_ack_map);
}
fn sync_first(&mut self, local_node_id: Uuid) {
let first_version = self.versions.first().as_ref().unwrap().version;
self.update(|layout| {
layout
.update_trackers
.sync_map
.set_max(local_node_id, first_version)
});
}
fn sync_ack(&mut self, local_node_id: Uuid) {
let sync_map_min = self.sync_map_min;
self.update(|layout| {
layout
.update_trackers
.sync_ack_map
.set_max(local_node_id, sync_map_min)
});
}
pub(crate) fn ack_max_free(&mut self, local_node_id: Uuid) -> bool {
let max_ack = self.max_free_ack();
let changed = self.update(|layout| {
layout
.update_trackers
.ack_map
.set_max(local_node_id, max_ack)
});
if changed {
info!("ack_until updated to {}", max_ack);
}
changed
}
pub(crate) fn max_free_ack(&self) -> u64 {
self.layout()
.versions
.iter()
.map(|x| x.version)
.take_while(|v| {
self.ack_lock
.get(v)
.map(|x| x.load(Ordering::Relaxed) == 0)
.unwrap_or(true)
})
.max()
.unwrap_or(self.min_stored())
}
}
