added more changes worker

src/hyperview.in/client/api_client.go

@@ -54,7 +54,7 @@ func NewApiClient(repoDir string) (*ApiClient, error) {
     return nil, err
   }
 
-  repo_info, err := rest_client.NewRESTClient(server_addr, c.RepoUriPath, http.DefaultClient)
+  repo_attrs, err := rest_client.NewRESTClient(server_addr, c.RepoUriPath, http.DefaultClient)
   if err != nil {
     return nil, err
   }
@@ -65,7 +65,7 @@ func NewApiClient(repoDir string) (*ApiClient, error) {
   code_sync := code_sync.NewClient(c.ServerAddr, repo_fs)
 
   return &ApiClient {
-    repoInfo: repo_info,
+    repoInfo: repo_attrs,
     codeSync: code_sync,
     repoFS: repo_fs,
   }, nil

src/hyperview.in/server/base/backoff/backoff.go

@@ -0,0 +1,47 @@
+package backoff
+
+import "time"
+
+//backoff ported from cenkalti/backoff
+
+// BackOff is a backoff policy for retrying an operation.
+type BackOff interface {
+  // returns duration 
+  NextBackOff() time.Duration
+
+  // Reset to initial state.
+  Reset()
+}
+
+// Stop indicates that no more retries should be made for use in NextBackOff().
+const Stop time.Duration = -1
+
+// ZeroBackOff is a fixed backoff policy whose backoff time is always zero,
+// meaning that the operation is retried immediately without waiting, indefinitely.
+type ZeroBackOff struct{}
+
+func (b *ZeroBackOff) Reset() {}
+
+func (b *ZeroBackOff) NextBackOff() time.Duration { return 0 }
+
+// StopBackOff is a fixed backoff policy that always returns backoff.Stop for
+// NextBackOff(), meaning that the operation should never be retried.
+type StopBackOff struct{}
+
+func (b *StopBackOff) Reset() {}
+
+func (b *StopBackOff) NextBackOff() time.Duration { return Stop }
+
+// ConstantBackOff is a backoff policy that always returns the same backoff delay.
+// This is in contrast to an exponential backoff policy,
+// which returns a delay that grows longer as you call NextBackOff() over and over again.
+type ConstantBackOff struct {
+  Interval time.Duration
+}
+
+func (b *ConstantBackOff) Reset()                     {}
+func (b *ConstantBackOff) NextBackOff() time.Duration { return b.Interval }
+
+func NewConstantBackOff(d time.Duration) *ConstantBackOff {
+  return &ConstantBackOff{Interval: d}
+}

src/hyperview.in/server/base/backoff/context.go

@@ -0,0 +1,59 @@
+package backoff
+
+import (
+	"context"
+	"time"
+)
+
+// BackOffContext is a backoff policy that stops retrying after the context
+// is canceled.
+type BackOffContext interface {
+	BackOff
+	Context() context.Context
+}
+
+type backOffContext struct {
+	BackOff
+	ctx context.Context
+}
+
+// WithContext returns a BackOffContext with context ctx
+//
+// ctx must not be nil
+func WithContext(b BackOff, ctx context.Context) BackOffContext {
+	if ctx == nil {
+		panic("nil context")
+	}
+
+	if b, ok := b.(*backOffContext); ok {
+		return &backOffContext{
+			BackOff: b.BackOff,
+			ctx:     ctx,
+		}
+	}
+
+	return &backOffContext{
+		BackOff: b,
+		ctx:     ctx,
+	}
+}
+
+func ensureContext(b BackOff) BackOffContext {
+	if cb, ok := b.(BackOffContext); ok {
+		return cb
+	}
+	return WithContext(b, context.Background())
+}
+
+func (b *backOffContext) Context() context.Context {
+	return b.ctx
+}
+
+func (b *backOffContext) NextBackOff() time.Duration {
+	select {
+	case <-b.Context().Done():
+		return Stop
+	default:
+		return b.BackOff.NextBackOff()
+	}
+}

src/hyperview.in/server/base/backoff/exponential.go

@@ -0,0 +1,147 @@
+package backoff
+
+import (
+	"math/rand"
+	"time"
+)
+
+/*
+ExponentialBackOff is a backoff implementation that increases the backoff
+period for each retry attempt using a randomization function that grows exponentially.
+NextBackOff() is calculated using the following formula:
+ randomized interval =
+     RetryInterval * (random value in range [1 - RandomizationFactor, 1 + RandomizationFactor])
+In other words NextBackOff() will range between the randomization factor
+percentage below and above the retry interval.
+For example, given the following parameters:
+ RetryInterval = 2
+ RandomizationFactor = 0.5
+ Multiplier = 2
+the actual backoff period used in the next retry attempt will range between 1 and 3 seconds,
+multiplied by the exponential, that is, between 2 and 6 seconds.
+
+Note: MaxInterval caps the RetryInterval and not the randomized interval.
+If the time elapsed since an ExponentialBackOff instance is created goes past the
+MaxElapsedTime, then the method NextBackOff() starts returning backoff.Stop.
+The elapsed time can be reset by calling Reset().
+Example: Given the following default arguments, for 10 tries the sequence will be,
+and assuming we go over the MaxElapsedTime on the 10th try:
+ Request #  RetryInterval (seconds)  Randomized Interval (seconds)
+  1          0.5                     [0.25,   0.75]
+  2          0.75                    [0.375,  1.125]
+  3          1.125                   [0.562,  1.687]
+  4          1.687                   [0.8435, 2.53]
+  5          2.53                    [1.265,  3.795]
+  6          3.795                   [1.897,  5.692]
+  7          5.692                   [2.846,  8.538]
+  8          8.538                   [4.269, 12.807]
+  9         12.807                   [6.403, 19.210]
+ 10         19.210                   backoff.Stop
+Note: Implementation is not thread-safe.
+*/
+
+type ExponentialBackOff struct {
+	InitialInterval     time.Duration
+	RandomizationFactor float64
+	Multiplier          float64
+	MaxInterval         time.Duration
+	// After MaxElapsedTime the ExponentialBackOff stops.
+	// It never stops if MaxElapsedTime == 0.
+	MaxElapsedTime time.Duration
+	Clock          Clock
+
+	currentInterval time.Duration
+	startTime       time.Time
+	random          *rand.Rand
+}
+
+// Clock is an interface that returns current time for BackOff.
+type Clock interface {
+	Now() time.Time
+}
+
+// Default values for ExponentialBackOff.
+const (
+	DefaultInitialInterval     = 500 * time.Millisecond
+	DefaultRandomizationFactor = 0.5
+	DefaultMultiplier          = 1.5
+	DefaultMaxInterval         = 60 * time.Second
+	DefaultMaxElapsedTime      = 15 * time.Minute
+)
+
+// NewExponentialBackOff creates an instance of ExponentialBackOff using default values.
+func NewExponentialBackOff() *ExponentialBackOff {
+	b := &ExponentialBackOff{
+		InitialInterval:     DefaultInitialInterval,
+		RandomizationFactor: DefaultRandomizationFactor,
+		Multiplier:          DefaultMultiplier,
+		MaxInterval:         DefaultMaxInterval,
+		MaxElapsedTime:      DefaultMaxElapsedTime,
+		Clock:               SystemClock,
+		random:              rand.New(rand.NewSource(time.Now().UnixNano())),
+	}
+	b.Reset()
+	return b
+}
+
+type systemClock struct{}
+
+func (t systemClock) Now() time.Time {
+	return time.Now()
+}
+
+// SystemClock implements Clock interface that uses time.Now().
+var SystemClock = systemClock{}
+
+// Reset the interval back to the initial retry interval and restarts the timer.
+func (b *ExponentialBackOff) Reset() {
+	b.currentInterval = b.InitialInterval
+	b.startTime = b.Clock.Now()
+}
+
+// NextBackOff calculates the next backoff interval using the formula:
+// 	Randomized interval = RetryInterval +/- (RandomizationFactor * RetryInterval)
+func (b *ExponentialBackOff) NextBackOff() time.Duration {
+	// Make sure we have not gone over the maximum elapsed time.
+	if b.MaxElapsedTime != 0 && b.GetElapsedTime() > b.MaxElapsedTime {
+		return Stop
+	}
+	defer b.incrementCurrentInterval()
+	if b.random == nil {
+		b.random = rand.New(rand.NewSource(time.Now().UnixNano()))
+	}
+	return getRandomValueFromInterval(b.RandomizationFactor, b.random.Float64(), b.currentInterval)
+}
+
+// GetElapsedTime returns the elapsed time since an ExponentialBackOff instance
+// is created and is reset when Reset() is called.
+//
+// The elapsed time is computed using time.Now().UnixNano(). It is
+// safe to call even while the backoff policy is used by a running
+// ticker.
+func (b *ExponentialBackOff) GetElapsedTime() time.Duration {
+	return b.Clock.Now().Sub(b.startTime)
+}
+
+// Increments the current interval by multiplying it with the multiplier.
+func (b *ExponentialBackOff) incrementCurrentInterval() {
+	// Check for overflow, if overflow is detected set the current interval to the max interval.
+	if float64(b.currentInterval) >= float64(b.MaxInterval)/b.Multiplier {
+		b.currentInterval = b.MaxInterval
+	} else {
+		b.currentInterval = time.Duration(float64(b.currentInterval) * b.Multiplier)
+	}
+}
+
+// Returns a random value from the following interval:
+// 	[randomizationFactor * currentInterval, randomizationFactor * currentInterval].
+func getRandomValueFromInterval(randomizationFactor, random float64, currentInterval time.Duration) time.Duration {
+	var delta = randomizationFactor * float64(currentInterval)
+	var minInterval = float64(currentInterval) - delta
+	var maxInterval = float64(currentInterval) + delta
+
+	// Get a random value from the range [minInterval, maxInterval].
+	// The formula used below has a +1 because if the minInterval is 1 and the maxInterval is 3 then
+	// we want a 33% chance for selecting either 1, 2 or 3.
+	return time.Duration(minInterval + (random * (maxInterval - minInterval + 1)))
+}

src/hyperview.in/server/base/backoff/retry.go

@@ -0,0 +1,78 @@
+package backoff
+
+import "time"
+
+// An Operation is executing by Retry() or RetryNotify().
+// The operation will be retried using a backoff policy if it returns an error.
+type Operation func() error
+
+// Notify is a notify-on-error function. It receives an operation error and
+// backoff delay if the operation failed (with an error).
+//
+// NOTE that if the backoff policy stated to stop retrying,
+// the notify function isn't called.
+type Notify func(error, time.Duration)
+
+// Retry the operation o until it does not return error or BackOff stops.
+// o is guaranteed to be run at least once.
+// It is the caller's responsibility to reset b after Retry returns.
+//
+// If o returns a *PermanentError, the operation is not retried, and the
+// wrapped error is returned.
+//
+// Retry sleeps the goroutine for the duration returned by BackOff after a
+// failed operation returns.
+func Retry(o Operation, b BackOff) error { return RetryNotify(o, b, nil) }
+
+// RetryNotify calls notify function with the error and wait duration
+// for each failed attempt before sleep.
+func RetryNotify(operation Operation, b BackOff, notify Notify) error {
+  var err error
+  var next time.Duration
+
+  cb := ensureContext(b)
+
+  b.Reset()
+  for {
+    if err = operation(); err == nil {
+      return nil
+    }
+
+    if permanent, ok := err.(*PermanentError); ok {
+      return permanent.Err
+    }
+
+    if next = b.NextBackOff(); next == Stop {
+      return err
+    }
+
+    if notify != nil {
+      notify(err, next)
+    }
+
+    t := time.NewTimer(next)
+
+    select {
+    case <-cb.Context().Done():
+      t.Stop()
+      return err
+    case <-t.C:
+    }
+  }
+}
+
+// PermanentError signals that the operation should not be retried.
+type PermanentError struct {
+  Err error
+}
+
+func (e *PermanentError) Error() string {
+  return e.Err.Error()
+}
+
+// Permanent wraps the given err in a *PermanentError.
+func Permanent(err error) *PermanentError {
+  return &PermanentError{
+    Err: err,
+  }
+}