Documentation
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Overview ¶
Package sequencer contains a number of sub-packages that implement various strategies for applying staged mutations.
Index ¶
Constants ¶
const ( DefaultFlushPeriod = 1 * time.Second DefaultFlushSize = 1_000 DefaultTaskGracePeriod = time.Minute DefaultParallelism = 16 DefaultQuiescentPeriod = 10 * time.Second DefaultRetireOffset = 24 * time.Hour DefaultScanSize = 10_000 DefaultTimestampLimit = 1_000 )
Defaults for flag bindings.
Variables ¶
This section is empty.
Functions ¶
func CommonProgress ¶
CommonProgress returns the minimum progress across all tables within the [Stat.Group]. If no progress has been made for one or more tables in the group, hlc.RangeEmpty will be returned.
func IsMarking ¶
func IsMarking(acc types.MultiAcceptor) bool
IsMarking returns true if the acceptor implements MarkingAcceptor or MarkingAcceptor is implemented by an acceptor somewhere in a delegate chain.
Types ¶
type Config ¶
type Config struct {
Chaos float32 // Set by tests to inject errors.
FlushPeriod time.Duration // Don't queue mutations for longer than this.
FlushSize int // Ideal target database transaction size
Parallelism int // The number of concurrent connections to use.
QuiescentPeriod time.Duration // How often to sweep for queued mutations.
RetireOffset time.Duration // Delay removal of applied mutations.
ScanSize int // Limit on staging-table read queries.
TaskGracePeriod time.Duration // How long to allow previous iteration to clean up.
TimestampLimit int // The maximum number of timestamps to operate on.
}
Config is an injection point common to sequencer implementations. Not all sequencers necessarily respond to all configuration options.
type MarkingAcceptor ¶
type MarkingAcceptor interface {
// IsMarking should return true.
IsMarking() bool
}
MarkingAcceptor is a marker interface to indicate that a types.MultiAcceptor will assume responsibility for calling types.Stager.MarkApplied.
type Sequencer ¶
type Sequencer interface {
// Start any goroutines necessary for operating within a
// [types.TableGroup] and return an acceptor for admitting mutations
// into that group. The Sequencer will monitor the
// [StartOptions.Bounds] for updates and periodically emit a Stat
// which reflects the Sequencer's current state. It is reasonable
// to extend the maximum value of the bounds over time, but the
// minimum value should not be advanced until all tables in the Stat
// have advanced to at least some common minimum value. When
// switching between different Sequencers at runtime, callers should
// discontinue updates to the bounds and ideally wait for the Stat
// variable to catch up.
Start(ctx *stopper.Context, opts *StartOptions) (types.MultiAcceptor, *notify.Var[Stat], error)
}
A Sequencer implements a lifecycle strategy for mutations. The various strategies may include immediate, best-effort, or fully-transactional behaviors.
The Sequencer type should also allow for composition of behaviors, e.g.: userscript dispatch.
type Shim ¶
type Shim interface {
// Wrap will modify the delegate's behavior. The shim should call
// [StartOptions.Copy] if the options passed to [Sequencer.Start]
// are to be modified before passing them to the delegate.
Wrap(ctx *stopper.Context, delegate Sequencer) (Sequencer, error)
}
A Shim allows the behaviors of another Sequencer to be modified.
type StartOptions ¶
type StartOptions struct {
Bounds *notify.Var[hlc.Range] // Control the range of eligible timestamps.
Delegate types.MultiAcceptor // The acceptor to use when continuing to process mutations.
Group *types.TableGroup // The tables that should be operated on.
MaxDeferred int // Back off after deferring this many mutations.
}
StartOptions is passed to [Sequencer.Start].
func (*StartOptions) Copy ¶
func (o *StartOptions) Copy() *StartOptions
Copy returns a deep copy of the options.
type Stat ¶
type Stat interface {
Copy() Stat // Copy returns a deep copy of the Stat.
Group() *types.TableGroup // The TableGroup that was passed to [Sequencer.Start].
Progress() *ident.TableMap[hlc.Range] // The times to which the members of the group have advanced.
}
Stat is an interface to allow for more specialized types to aid in testing.
Source Files
Directories
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| Path | Synopsis |
|---|---|
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Package besteffort contains a best-effort implementation of types.MultiAcceptor.
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Package besteffort contains a best-effort implementation of types.MultiAcceptor. |
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Package chaos allows errors to be introduced in a sequencer stack.
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Package chaos allows errors to be introduced in a sequencer stack. |
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Package core contains a sequencer implementation that preserves source transactions and relative timestamps.
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Package core contains a sequencer implementation that preserves source transactions and relative timestamps. |
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Package immediate contains a trivial sequencer.Sequencer implementation which writes data directly to the configured acceptor.
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Package immediate contains a trivial sequencer.Sequencer implementation which writes data directly to the configured acceptor. |
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Package retire contains a utility for removing old mutations.
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Package retire contains a utility for removing old mutations. |
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Package scheduler contains Sequencer-specific utilities for ensuring ordered access to rows.
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Package scheduler contains Sequencer-specific utilities for ensuring ordered access to rows. |
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Package script provides an API shim that integrates the userscript into the sequencer.Sequencer API.
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Package script provides an API shim that integrates the userscript into the sequencer.Sequencer API. |
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Package seqtest provides a test fixture for instantiating sequencers and other general-purpose test helpers.
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Package seqtest provides a test fixture for instantiating sequencers and other general-purpose test helpers. |
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Package sequtil contains sequencer utility methods.
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Package sequtil contains sequencer utility methods. |
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Package switcher contains a meta-Sequencer that switches between various modes of operation.
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Package switcher contains a meta-Sequencer that switches between various modes of operation. |