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feat: export numG and qSize #9

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feat: export numG and qSize #9

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18 changes: 9 additions & 9 deletions errgroup.go
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Original file line number Diff line number Diff line change
Expand Up @@ -44,11 +44,11 @@ type Group struct {
err error

// numG is the maximum number of goroutines that can be started.
numG int
NumG int

// qSize is the capacity of qCh, used for buffering funcs
// passed to method Go.
qSize int
QSize int

// qCh is the buffer used to hold funcs passed to method Go
// before they are picked up by worker goroutines.
Expand Down Expand Up @@ -80,7 +80,7 @@ func WithContext(ctx context.Context) (*Group, context.Context) {
// also <= 0, a qSize of runtime.NumCPU is used.
func WithContextN(ctx context.Context, numG, qSize int) (*Group, context.Context) {
ctx, cancel := context.WithCancel(ctx)
return &Group{cancel: cancel, numG: numG, qSize: qSize}, ctx
return &Group{cancel: cancel, NumG: numG, QSize: qSize}, ctx
}

// Wait blocks until all function calls from the Go method have returned, then
Expand Down Expand Up @@ -126,21 +126,21 @@ func (g *Group) Go(f func() error) {
// The zero value of numG would mean no worker goroutine
// would be created, which would be daft.
// We want the "effective" zero value to be runtime.NumCPU.
if g.numG == 0 {
if g.NumG == 0 {
// Benchmarking has shown that the optimal numG and
// qSize values depend on the particular workload. In
// the absence of any other deciding factor, we somewhat
// arbitrarily default to NumCPU, which seems to perform
// reasonably in benchmarks. Users that care about performance
// tuning will use the WithContextN func to specify the numG
// and qSize args.
g.numG = runtime.NumCPU()
if g.qSize == 0 {
g.qSize = g.numG
g.NumG = runtime.NumCPU()
if g.QSize == 0 {
g.QSize = g.NumG
}
}

g.qCh = make(chan func() error, g.qSize)
g.qCh = make(chan func() error, g.QSize)

// Being that g.Go has been invoked, we'll need at
// least one goroutine.
Expand Down Expand Up @@ -174,7 +174,7 @@ func (g *Group) maybeStartG() {

// We have at least one item in qCh. Maybe it's time to start
// a new worker goroutine?
if atomic.AddInt64(&g.gCount, 1) > int64(g.numG) {
if atomic.AddInt64(&g.gCount, 1) > int64(g.NumG) {
// Nope: not allowed. Starting a new goroutine would put us
// over the numG limit, so we back out.
atomic.AddInt64(&g.gCount, -1)
Expand Down