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Allow failover for replicas

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This commit is contained in:
Jose Fernandez (magec)
2024-11-06 12:59:20 +01:00
parent 0ee59c0c40
commit 16a2cece21
6 changed files with 174 additions and 79 deletions
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51
src/pool.rs
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@@ -162,6 +162,9 @@ pub struct PoolSettings {
// Default server role to connect to.
pub default_role: Option<Role>,
// Whether or not we should use primary when replicas are unavailable
pub replica_to_primary_failover_enabled: bool,
// Enable/disable query parser.
pub query_parser_enabled: bool,
@@ -219,6 +222,7 @@ impl Default for PoolSettings {
user: User::default(),
db: String::default(),
default_role: None,
replica_to_primary_failover_enabled: false,
query_parser_enabled: false,
query_parser_max_length: None,
query_parser_read_write_splitting: false,
@@ -531,6 +535,8 @@ impl ConnectionPool {
"primary" => Some(Role::Primary),
_ => unreachable!(),
},
replica_to_primary_failover_enabled: pool_config
.replica_to_primary_failover_enabled,
query_parser_enabled: pool_config.query_parser_enabled,
query_parser_max_length: pool_config.query_parser_max_length,
query_parser_read_write_splitting: pool_config
@@ -731,6 +737,19 @@ impl ConnectionPool {
});
}
// If the role is replica and we allow sending traffic to primary when replicas are unavailble,
// we add primary address at the end of the list of candidates, this way it will be tried when
// replicas are all unavailable.
if role == Role::Replica && self.settings.replica_to_primary_failover_enabled {
let mut primaries = self
.addresses
.iter()
.flatten()
.filter(|address| address.role == Role::Primary)
.collect::<Vec<&Address>>();
candidates.insert(0, primaries.pop().unwrap());
}
// Indicate we're waiting on a server connection from a pool.
let now = Instant::now();
client_stats.waiting();
@@ -935,24 +954,28 @@ impl ConnectionPool {
return true;
}
// Check if all replicas are banned, in that case unban all of them
let replicas_available = self.addresses[address.shard]
.iter()
.filter(|addr| addr.role == Role::Replica)
.count();
// If we have replica to primary failover we should not unban replicas
// as we still have the primary to server traffic.
if !self.settings.replica_to_primary_failover_enabled {
// Check if all replicas are banned, in that case unban all of them
let replicas_available = self.addresses[address.shard]
.iter()
.filter(|addr| addr.role == Role::Replica)
.count();
debug!("Available targets: {}", replicas_available);
debug!("Available targets: {}", replicas_available);
let read_guard = self.banlist.read();
let all_replicas_banned = read_guard[address.shard].len() == replicas_available;
drop(read_guard);
let read_guard = self.banlist.read();
let all_replicas_banned = read_guard[address.shard].len() == replicas_available;
drop(read_guard);
if all_replicas_banned {
let mut write_guard = self.banlist.write();
warn!("Unbanning all replicas.");
write_guard[address.shard].clear();
if all_replicas_banned {
let mut write_guard = self.banlist.write();
warn!("Unbanning all replicas.");
write_guard[address.shard].clear();
return true;
return true;
}
}
// Check if ban time is expired