Documentation
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Overview ¶
Package throttler contains code to throttle the rate of writes to a table.
Index ¶
Constants ¶
const MySQL8LagQuery = `` /* 1097-byte string literal not displayed */
MySQL8LagQuery is a query that is used to get the lag between the source and the replica. The implementation is described in https://github.com/cashapp/spirit/issues/286 It uses performance_schema instead of a heartbeat injection or seconds_behind_source.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type MySQL80Replica ¶
type MySQL80Replica struct {
Repl
// contains filtered or unexported fields
}
func (*MySQL80Replica) Close ¶
func (l *MySQL80Replica) Close() error
func (*MySQL80Replica) Open ¶
func (l *MySQL80Replica) Open() error
Open starts the lag monitor. This is not gh-ost. The lag monitor is primitive because the requirement is only for DR, and not for up-to-date read-replicas. Because chunk-sizes are typically 500ms, getting fine-grained metrics is not realistic. We only check the replica every 5 seconds, and typically allow up to 120s of replica lag, which is a lot.
func (*MySQL80Replica) UpdateLag ¶
func (l *MySQL80Replica) UpdateLag() error
UpdateLag is a MySQL 8.0+ implementation of lag that is a better approximation than "seconds_behind_source". It requires performance_schema to be enabled.
type Noop ¶
type Noop struct {
// contains filtered or unexported fields
}
func (*Noop) IsThrottled ¶
type Repl ¶
type Repl struct {
// contains filtered or unexported fields
}
func (*Repl) BlockWait ¶
func (l *Repl) BlockWait()
BlockWait blocks until the lag is within the tolerance, or up to 60s to allow some progress to be made.
func (*Repl) IsThrottled ¶
type Throttler ¶
type Throttler interface {
Open() error
Close() error
IsThrottled() bool
BlockWait()
UpdateLag() error
}
func NewReplicationThrottler ¶
func NewReplicationThrottler(replica *sql.DB, lagTolerance time.Duration, logger loggers.Advanced) (Throttler, error)
NewReplicationThrottler returns a Throttler that is appropriate for the current replica. It will return a MySQL80Replica throttler if the version is detected as 8.0, and a MySQL57Replica throttler otherwise. It returns an error if querying for either fails, i.e. it might not be a valid DB connection.
Source Files