LogDog: Add collector service implementation.

common/parallel/workPool.go

Index: common/parallel/workPool.go
diff --git a/common/parallel/workPool.go b/common/parallel/workPool.go
index 0e749eb07e108445b0cc357afbdeea328536673b..e27f5b828d7bf8e3ee6bee35540b4e08b74b953d 100644
--- a/common/parallel/workPool.go
+++ b/common/parallel/workPool.go
@@ -23,8 +23,17 @@ func WorkPool(workers int, gen func(chan<- func() error)) error {
 	}
 
 	sem := make(Semaphore, workers)
-	errchan := make(chan error, workers)
-	funchan := make(chan func() error, workers)
+	return Run(sem, gen)
+}
+
+// Run executes task functions produced by a generator method. Execution is
+// throttled by an optional Semaphore, requiring a token prior to dispatch.
+//
+// Run blocks until all the generator completes and all workers have finished
+// their tasks, returning a MultiError if a failure was encountered.
+func Run(sem Semaphore, gen func(chan<- func() error)) error {

[dnj (Google), 2016/01/21 04:36:24]

Useful b/c the FanOutIn model is great, but sometimes you want to share a
constraint with other FanOutIns.

+	errchan := make(chan error, cap(sem))
+	funchan := make(chan func() error, cap(sem))
 
 	go func() {
 		defer close(funchan)