Add Pool.Stat

pool.go

@@ -7,10 +7,10 @@ import (
 )
 
 const (
-	resourceStatusCreating = 0
-	resourceStatusIdle     = iota
-	resourceStatusAcquired = iota
-	resourceStatusHijacked = iota
+	resourceStatusConstructing = 0
+	resourceStatusIdle         = iota
+	resourceStatusAcquired     = iota
+	resourceStatusHijacked     = iota
 )
 
 // ErrClosedPool occurs on an attempt to get a connection from a closed pool.
@@ -96,20 +96,59 @@ func (p *Pool) Close() {
 	p.destructWG.Wait()
 }
 
-// Size returns the current size of the pool.
-func (p *Pool) Size() int {
-	p.cond.L.Lock()
-	n := len(p.allResources)
-	p.cond.L.Unlock()
-	return n
+type Stat struct {
+	constructing int
+	acquired     int
+	idle         int
+	maxSize      int
 }
 
-// MaxSize returns the current maximum size of the pool.
-func (p *Pool) MaxSize() int {
+// Size returns the total number of resources in the pool.
+func (s *Stat) Size() int {
+	return s.constructing + s.acquired + s.idle
+}
+
+// Constructing returns the number of resources with construction in progress in
+// the pool.
+func (s *Stat) Constructing() int {
+	return s.constructing
+}
+
+// Acquired returns the number of acquired resources in the pool.
+func (s *Stat) Acquired() int {
+	return s.acquired
+}
+
+// Idle returns the number of idle resources in the pool.
+func (s *Stat) Idle() int {
+	return s.idle
+}
+
+// MaxSize returns the maximum size of the pool
+func (s *Stat) MaxSize() int {
+	return s.maxSize
+}
+
+// Stat returns the current pool statistics.
+func (p *Pool) Stat() *Stat {
 	p.cond.L.Lock()
-	n := p.maxSize
+	s := &Stat{
+		maxSize: p.maxSize,
+	}
+
+	for _, res := range p.allResources {
+		switch res.status {
+		case resourceStatusConstructing:
+			s.constructing += 1
+		case resourceStatusIdle:
+			s.idle += 1
+		case resourceStatusAcquired:
+			s.acquired += 1
+		}
+	}
+
 	p.cond.L.Unlock()
-	return n
+	return s
 }
 
 // Acquire gets a resource from the pool. If no resources are available and the pool
@@ -142,7 +181,7 @@ func (p *Pool) Acquire(ctx context.Context) (*Resource, error) {
 
 		// If there is room to create a resource do so
 		if len(p.allResources) < p.maxSize {
-			res := &Resource{pool: p, status: resourceStatusCreating}
+			res := &Resource{pool: p, status: resourceStatusConstructing}
 			p.allResources = append(p.allResources, res)
 			p.cond.L.Unlock()
 

pool_test.go

@@ -113,7 +113,7 @@ func TestPoolAcquireDoesNotCreatesResourceWhenItWouldExceedMaxSize(t *testing.T)
 	wg.Wait()
 
 	assert.Equal(t, 1, createCounter.Value())
-	assert.Equal(t, 1, pool.Size())
+	assert.Equal(t, 1, pool.Stat().Size())
 }
 
 func TestPoolAcquireWithCancellableContext(t *testing.T) {
@@ -140,7 +140,7 @@ func TestPoolAcquireWithCancellableContext(t *testing.T) {
 	wg.Wait()
 
 	assert.Equal(t, 1, createCounter.Value())
-	assert.Equal(t, 1, pool.Size())
+	assert.Equal(t, 1, pool.Stat().Size())
 }
 
 func TestPoolAcquireReturnsErrorFromFailedResourceCreate(t *testing.T) {
@@ -261,6 +261,55 @@ func TestPoolCloseBlocksUntilAllResourcesReleasedAndClosed(t *testing.T) {
 	assert.Equal(t, len(resources), closeCalls.Value())
 }
 
+func TestPoolStat(t *testing.T) {
+	startWaitChan := make(chan struct{})
+	waitingChan := make(chan struct{})
+	endWaitChan := make(chan struct{})
+
+	var createCalls Counter
+	createFunc := func(ctx context.Context) (interface{}, error) {
+		select {
+		case <-startWaitChan:
+			close(waitingChan)
+			<-endWaitChan
+		default:
+		}
+
+		return createCalls.Next(), nil
+	}
+	pool := puddle.NewPool(createFunc, stubCloseRes, 10)
+	defer pool.Close()
+
+	resAcquired, err := pool.Acquire(context.Background())
+	require.Nil(t, err)
+
+	close(startWaitChan)
+	go func() {
+		res, err := pool.Acquire(context.Background())
+		require.Nil(t, err)
+		res.Release()
+	}()
+	<-waitingChan
+	stat := pool.Stat()
+
+	assert.Equal(t, 2, stat.Size())
+	assert.Equal(t, 1, stat.Constructing())
+	assert.Equal(t, 1, stat.Acquired())
+	assert.Equal(t, 0, stat.Idle())
+	assert.Equal(t, 10, stat.MaxSize())
+
+	resAcquired.Release()
+
+	stat = pool.Stat()
+	assert.Equal(t, 2, stat.Size())
+	assert.Equal(t, 1, stat.Constructing())
+	assert.Equal(t, 0, stat.Acquired())
+	assert.Equal(t, 1, stat.Idle())
+	assert.Equal(t, 10, stat.MaxSize())
+
+	close(endWaitChan)
+}
+
 func TestResourceDestroyRemovesResourceFromPool(t *testing.T) {
 	createFunc, _ := createCreateResourceFunc()
 	var closeCalls Counter
@@ -276,7 +325,7 @@ func TestResourceDestroyRemovesResourceFromPool(t *testing.T) {
 
 	res.Hijack()
 
-	assert.Equal(t, 0, pool.Size())
+	assert.Equal(t, 0, pool.Stat().Size())
 	assert.Equal(t, 0, closeCalls.Value())
 }
 
@@ -288,9 +337,9 @@ func TestResourceHijackRemovesResourceFromPoolButDoesNotDestroy(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, 1, res.Value())
 
-	assert.Equal(t, 1, pool.Size())
+	assert.Equal(t, 1, pool.Stat().Size())
 	res.Destroy()
-	assert.Equal(t, 0, pool.Size())
+	assert.Equal(t, 0, pool.Stat().Size())
 }
 
 func TestPoolAcquireReturnsErrorWhenPoolIsClosed(t *testing.T) {