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package swo
import (
"context"
"fmt"
"sync"
"github.com/jackc/pgx/v5"
"github.com/target/goalert/swo/swogrp"
"github.com/target/goalert/swo/swosync"
)
// Executor is responsible for executing the switchover process.
type Executor struct {
mgr *Manager
stateCh chan execState
wf *WithFunc[*swosync.LogicalReplicator]
rep *swosync.LogicalReplicator
mx sync.Mutex
}
// NewExecutor initializes a new Executor for the given Manager.
func NewExecutor(mgr *Manager) *Executor {
e := &Executor{
mgr: mgr,
stateCh: make(chan execState, 1),
}
e.stateCh <- execStateIdle
e.wf = NewWithFunc(func(ctx context.Context, fn func(*swosync.LogicalReplicator)) error {
return mgr.withConnFromBoth(ctx, func(ctx context.Context, oldConn, newConn *pgx.Conn) error {
rep := swosync.NewLogicalReplicator()
rep.SetSourceDB(oldConn)
rep.SetDestinationDB(newConn)
rep.SetProgressFunc(mgr.taskMgr.Statusf)
fn(rep)
return nil
})
})
return e
}
type execState int
const (
execStateIdle execState = iota
execStateSync
)
var _ swogrp.Executor = (*Executor)(nil)
// Sync begins the switchover process by resetting and starting the logical replication process.
func (e *Executor) Sync(ctx context.Context) error {
e.mx.Lock()
defer e.mx.Unlock()
if e.rep != nil {
return fmt.Errorf("already syncing")
}
rep, err := e.wf.Begin(e.mgr.Logger.BackgroundContext())
if err != nil {
return err
}
err = rep.ResetChangeTracking(ctx)
if err != nil {
return fmt.Errorf("reset: %w", err)
}
err = rep.StartTrackingChanges(ctx)
if err != nil {
return fmt.Errorf("start: %w", err)
}
err = rep.FullInitialSync(ctx)
if err != nil {
return fmt.Errorf("initial sync: %w", err)
}
for i := 0; i < 10; i++ {
err = rep.LogicalSync(ctx)
if err != nil {
return fmt.Errorf("logical sync: %w", err)
}
}
e.rep = rep
return nil
}
// Exec executes the switchover process, blocking until it is complete.
func (e *Executor) Exec(ctx context.Context) error {
e.mx.Lock()
defer e.mx.Unlock()
if e.rep == nil {
return fmt.Errorf("not syncing")
}
rep := e.rep
e.rep = nil
for i := 0; i < 10; i++ {
err := rep.LogicalSync(ctx)
if err != nil {
return fmt.Errorf("logical sync (after pause): %w", err)
}
}
err := rep.FinalSync(ctx)
if err != nil {
return fmt.Errorf("final sync: %w", err)
}
return nil
}
// Cancel cancels the switchover process.
func (e *Executor) Cancel() { e.wf.Cancel() }
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