github.com/mattyw/juju@v0.0.0-20140610034352-732aecd63861/environs/testing/polling.go (about)

     1  // Copyright 2012, 2013 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package testing
     5  
     6  import (
     7  	"github.com/juju/utils"
     8  
     9  	"github.com/juju/juju/provider/common"
    10  )
    11  
    12  // impatientAttempt is an extremely short polling time suitable for tests.
    13  // It polls at least once, never delays, and times out very quickly.
    14  var impatientAttempt = utils.AttemptStrategy{}
    15  
    16  // savedAttemptStrategy holds the state needed to restore an AttemptStrategy's
    17  // original setting.
    18  type savedAttemptStrategy struct {
    19  	address  *utils.AttemptStrategy
    20  	original utils.AttemptStrategy
    21  }
    22  
    23  // saveAttemptStrategies captures the information required to restore the
    24  // given AttemptStrategy objects.
    25  func saveAttemptStrategies(strategies []*utils.AttemptStrategy) []savedAttemptStrategy {
    26  	savedStrategies := make([]savedAttemptStrategy, len(strategies))
    27  	for index, strategy := range strategies {
    28  		savedStrategies[index] = savedAttemptStrategy{
    29  			address:  strategy,
    30  			original: *strategy,
    31  		}
    32  	}
    33  	return savedStrategies
    34  }
    35  
    36  // restore returns a saved strategy to its original configuration.
    37  func (saved savedAttemptStrategy) restore() {
    38  	*saved.address = saved.original
    39  }
    40  
    41  // restoreAttemptStrategies restores multiple saved AttemptStrategies.
    42  func restoreAttemptStrategies(strategies []savedAttemptStrategy) {
    43  	for _, saved := range strategies {
    44  		saved.restore()
    45  	}
    46  }
    47  
    48  // internalPatchAttemptStrategies sets the given AttemptStrategy objects
    49  // to the impatientAttempt configuration, and returns a function that restores
    50  // the original configurations.
    51  func internalPatchAttemptStrategies(strategies []*utils.AttemptStrategy) func() {
    52  	snapshot := saveAttemptStrategies(strategies)
    53  	for _, strategy := range strategies {
    54  		*strategy = impatientAttempt
    55  	}
    56  	return func() { restoreAttemptStrategies(snapshot) }
    57  }
    58  
    59  // TODO: Everything up to this point is generic.  Move it to utils?
    60  
    61  // PatchAttemptStrategies patches environs' global polling strategy, plus any
    62  // otther AttemptStrategy objects whose addresses you pass, to very short
    63  // polling and timeout times so that tests can run fast.
    64  // It returns a cleanup function that restores the original settings.  You must
    65  // call this afterwards.
    66  func PatchAttemptStrategies(strategies ...*utils.AttemptStrategy) func() {
    67  	// The one irregularity here is that LongAttempt goes on the list of
    68  	// strategies that need patching.  To keep testing simple, we treat
    69  	// the given attempts and LongAttempt as a single slice from here on.
    70  	combinedStrategies := append(strategies, &common.LongAttempt, &common.ShortAttempt)
    71  	return internalPatchAttemptStrategies(combinedStrategies)
    72  }