github.com/makyo/juju@v0.0.0-20160425123129-2608902037e9/worker/resumer/resumer.go (about)

     1  // Copyright 2012, 2013 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package resumer
     5  
     6  import (
     7  	"fmt"
     8  	"time"
     9  
    10  	"github.com/juju/juju/worker"
    11  	"github.com/juju/loggo"
    12  	"launchpad.net/tomb"
    13  )
    14  
    15  var logger = loggo.GetLogger("juju.worker.resumer")
    16  
    17  // defaultInterval is the standard value for the interval setting.
    18  const defaultInterval = time.Minute
    19  
    20  // interval sets how often the resuming is called.
    21  var interval = defaultInterval
    22  
    23  // TransactionResumer defines the interface for types capable to
    24  // resume transactions.
    25  type TransactionResumer interface {
    26  	// ResumeTransactions resumes all pending transactions.
    27  	ResumeTransactions() error
    28  }
    29  
    30  // Resumer is responsible for a periodical resuming of pending transactions.
    31  type Resumer struct {
    32  	tomb tomb.Tomb
    33  	tr   TransactionResumer
    34  }
    35  
    36  // NewResumer periodically resumes pending transactions.
    37  var NewResumer = func(tr TransactionResumer) worker.Worker {
    38  	rr := &Resumer{tr: tr}
    39  	go func() {
    40  		defer rr.tomb.Done()
    41  		rr.tomb.Kill(rr.loop())
    42  	}()
    43  	return rr
    44  }
    45  
    46  func (rr *Resumer) String() string {
    47  	return fmt.Sprintf("resumer")
    48  }
    49  
    50  func (rr *Resumer) Kill() {
    51  	rr.tomb.Kill(nil)
    52  }
    53  
    54  func (rr *Resumer) Wait() error {
    55  	return rr.tomb.Wait()
    56  }
    57  
    58  func (rr *Resumer) loop() error {
    59  	for {
    60  		select {
    61  		case <-rr.tomb.Dying():
    62  			return tomb.ErrDying
    63  		case <-time.After(interval):
    64  			// TODO(fwereade): 2016-03-17 lp:1558657
    65  			if err := rr.tr.ResumeTransactions(); err != nil {
    66  				logger.Errorf("cannot resume transactions: %v", err)
    67  			}
    68  		}
    69  	}
    70  }