1 files changed, 152 insertions, 0 deletions
diff --git a/external_test.go b/external_test.go
new file mode 100644
index 0000000..ae29ca8
--- /dev/null
+++ b/external_test.go
@@ -0,0 +1,152 @@
+package stm_test
+
+import (
+	"sync"
+	"testing"
+
+	"github.com/anacrolix/missinggo/iter"
+	"github.com/anacrolix/stm"
+	"github.com/anacrolix/stm/stmutil"
+)
+
+const maxTokens = 25
+
+func BenchmarkThunderingHerdCondVar(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		var mu sync.Mutex
+		consumer := sync.NewCond(&mu)
+		generator := sync.NewCond(&mu)
+		done := false
+		tokens := 0
+		var pending sync.WaitGroup
+		for range iter.N(1000) {
+			pending.Add(1)
+			go func() {
+				mu.Lock()
+				for {
+					if tokens > 0 {
+						tokens--
+						generator.Signal()
+						break
+					}
+					consumer.Wait()
+				}
+				mu.Unlock()
+				pending.Done()
+			}()
+		}
+		go func() {
+			mu.Lock()
+			for !done {
+				if tokens < maxTokens {
+					tokens++
+					consumer.Signal()
+				} else {
+					generator.Wait()
+				}
+			}
+			mu.Unlock()
+		}()
+		pending.Wait()
+		mu.Lock()
+		done = true
+		generator.Signal()
+		mu.Unlock()
+	}
+
+}
+
+func BenchmarkThunderingHerd(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		done := stm.NewBuiltinEqVar(false)
+		tokens := stm.NewBuiltinEqVar(0)
+		pending := stm.NewBuiltinEqVar(0)
+		for range iter.N(1000) {
+			stm.Atomically(stm.VoidOperation(func(tx *stm.Tx) {
+				tx.Set(pending, tx.Get(pending).(int)+1)
+			}))
+			go func() {
+				stm.Atomically(stm.VoidOperation(func(tx *stm.Tx) {
+					t := tx.Get(tokens).(int)
+					if t > 0 {
+						tx.Set(tokens, t-1)
+						tx.Set(pending, tx.Get(pending).(int)-1)
+					} else {
+						tx.Retry()
+					}
+				}))
+			}()
+		}
+		go func() {
+			for stm.Atomically(func(tx *stm.Tx) interface{} {
+				if tx.Get(done).(bool) {
+					return false
+				}
+				tx.Assert(tx.Get(tokens).(int) < maxTokens)
+				tx.Set(tokens, tx.Get(tokens).(int)+1)
+				return true
+			}).(bool) {
+			}
+		}()
+		stm.Atomically(stm.VoidOperation(func(tx *stm.Tx) {
+			tx.Assert(tx.Get(pending).(int) == 0)
+		}))
+		stm.AtomicSet(done, true)
+	}
+}
+
+func BenchmarkInvertedThunderingHerd(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		done := stm.NewBuiltinEqVar(false)
+		tokens := stm.NewBuiltinEqVar(0)
+		pending := stm.NewVar(stmutil.NewSet())
+		for range iter.N(1000) {
+			ready := stm.NewVar(false)
+			stm.Atomically(stm.VoidOperation(func(tx *stm.Tx) {
+				tx.Set(pending, tx.Get(pending).(stmutil.Settish).Add(ready))
+			}))
+			go func() {
+				stm.Atomically(stm.VoidOperation(func(tx *stm.Tx) {
+					tx.Assert(tx.Get(ready).(bool))
+					set := tx.Get(pending).(stmutil.Settish)
+					if !set.Contains(ready) {
+						panic("couldn't find ourselves in pending")
+					}
+					tx.Set(pending, set.Delete(ready))
+				}))
+				//b.Log("waiter finished")
+			}()
+		}
+		go func() {
+			for stm.Atomically(func(tx *stm.Tx) interface{} {
+				if tx.Get(done).(bool) {
+					return false
+				}
+				tx.Assert(tx.Get(tokens).(int) < maxTokens)
+				tx.Set(tokens, tx.Get(tokens).(int)+1)
+				return true
+			}).(bool) {
+			}
+		}()
+		go func() {
+			for stm.Atomically(func(tx *stm.Tx) interface{} {
+				tx.Assert(tx.Get(tokens).(int) > 0)
+				tx.Set(tokens, tx.Get(tokens).(int)-1)
+				tx.Get(pending).(stmutil.Settish).Range(func(i interface{}) bool {
+					ready := i.(*stm.Var)
+					if !tx.Get(ready).(bool) {
+						tx.Set(ready, true)
+						return false
+					}
+					return true
+				})
+				return !tx.Get(done).(bool)
+			}).(bool) {
+			}
+		}()
+		stm.Atomically(stm.VoidOperation(func(tx *stm.Tx) {
+			tx.Assert(tx.Get(pending).(stmutil.Lenner).Len() == 0)
+		}))
+		stm.AtomicSet(done, true)
+	}
+}