mirror of
https://gitlab.com/pulsechaincom/prysm-pulse.git
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61 lines
2.1 KiB
Go
61 lines
2.1 KiB
Go
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package startup
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import (
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"context"
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"github.com/pkg/errors"
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)
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var errClockSet = errors.New("refusing to change clock after it is set")
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// ClockSynchronizer provides a synchronization mechanism for services that rely on the genesis time and validator root
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// being known before getting to work.
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type ClockSynchronizer struct {
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ready chan struct{}
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c *Clock
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}
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// ClockWaiter specifies the WaitForClock method. ClockSynchronizer works in a 1:N pattern, with 1 thread calling
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// SetClock, and the others blocking on a call to WaitForClock until the expected *Clock value is set.
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type ClockWaiter interface {
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WaitForClock(context.Context) (*Clock, error)
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}
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// ClockSetter specifies the SetClock method. ClockSynchronizer works in a 1:N pattern, so in a given graph of services,
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// only one service should be given the ClockSetter, and all others relying on the service's activation should use
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// ClockWaiter.
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type ClockSetter interface {
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SetClock(c *Clock) error
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}
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// SetClock sets the Clock value `c` and unblocks all threads waiting for `c` via WaitForClock.
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// Calling SetClock more than once will return an error, as calling this function is meant to be a signal
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// that the system is ready to start.
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func (w *ClockSynchronizer) SetClock(c *Clock) error {
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if w.c != nil {
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return errors.Wrapf(errClockSet, "when SetClock called, Clock already set to time=%d", w.c.GenesisTime().Unix())
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}
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w.c = c
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close(w.ready)
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return nil
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}
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// WaitForClock will block the caller until the *Clock value is available. If the provided context is canceled (eg via
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// a deadline set upstream), the function will return the error given by ctx.Err().
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func (w *ClockSynchronizer) WaitForClock(ctx context.Context) (*Clock, error) {
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select {
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case <-w.ready:
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return w.c, nil
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case <-ctx.Done():
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return nil, ctx.Err()
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}
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}
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// NewClockSynchronizer initializes a single instance of ClockSynchronizer that must be used by all ClockWaiters that
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// need to be synchronized to a ClockSetter (ie blockchain service).
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func NewClockSynchronizer() *ClockSynchronizer {
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return &ClockSynchronizer{
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ready: make(chan struct{}),
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}
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}
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