Documentation
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Overview ¶
Package postgrescoord provides Postgres-backed cron.Claimer and cron.Elector implementations through database/sql. It uses server time, so application clock skew does not affect claims or leadership leases.
Index ¶
Constants ¶
const ( // DefaultLeaderName scopes the default leadership lease row. DefaultLeaderName = "default" // DefaultLeaderTTL is the leadership lease. Failover can take one TTL. DefaultLeaderTTL = 30 * time.Second )
const ( // DefaultClaimsTable stores fire claims. DefaultClaimsTable = "cron_claims" // DefaultLeaderTable stores leadership leases. DefaultLeaderTable = "cron_leader" )
const ( // DefaultClaimTTL is the time a fire claim remains reserved. It must cover // the largest expected jitter, clock skew, and delayed catch-up window. DefaultClaimTTL = 10 * time.Minute )
Variables ¶
This section is empty.
Functions ¶
Types ¶
type Claimer ¶
type Claimer struct {
// contains filtered or unexported fields
}
Claimer stores fire claims in Postgres. Expired claims for the same fire key are replaced atomically.
func NewClaimer ¶
func NewClaimer(db *sql.DB, opts ...ClaimerOption) (*Claimer, error)
NewClaimer constructs a Postgres fire Claimer. The claims table must exist; see Migrate. The driver must support sql.Result.RowsAffected.
type ClaimerOption ¶
type ClaimerOption func(*claimerConfig) error
ClaimerOption configures a Claimer.
func WithClaimTTL ¶
func WithClaimTTL(ttl time.Duration) ClaimerOption
WithClaimTTL overrides DefaultClaimTTL.
func WithClaimsTable ¶
func WithClaimsTable(table string) ClaimerOption
WithClaimsTable overrides DefaultClaimsTable.
type Elector ¶
type Elector struct {
// contains filtered or unexported fields
}
Elector is a lease-based cron.Elector. IsLeader renews a lease already held by this process; no background goroutine or Close is required.
func NewElector ¶
func NewElector(db *sql.DB, opts ...ElectorOption) (*Elector, error)
NewElector constructs a lease-based Postgres Elector. The leader table must exist; see Migrate.
type ElectorOption ¶
type ElectorOption func(*electorConfig) error
ElectorOption configures an Elector.
func WithLeaderName ¶
func WithLeaderName(name string) ElectorOption
WithLeaderName scopes the lease row, letting several fleets share a table.
func WithLeaderTTL ¶
func WithLeaderTTL(ttl time.Duration) ElectorOption
WithLeaderTTL overrides DefaultLeaderTTL.
func WithLeaderTable ¶
func WithLeaderTable(table string) ElectorOption
WithLeaderTable overrides DefaultLeaderTable.
Source Files