From e1243883d65512f5699eb8c6a99f0059fda10058 Mon Sep 17 00:00:00 2001
From: Menghan Li <menghanl@google.com>
Date: Fri, 6 May 2016 14:49:12 -0700
Subject: [PATCH] Merge histograms into one histogram in getStats

---
 benchmark/worker/benchmark_client.go | 52 +++++++++++++++++-----------
 1 file changed, 32 insertions(+), 20 deletions(-)

diff --git a/benchmark/worker/benchmark_client.go b/benchmark/worker/benchmark_client.go
index 9c4c7a64..03468950 100644
--- a/benchmark/worker/benchmark_client.go
+++ b/benchmark/worker/benchmark_client.go
@@ -235,7 +235,7 @@ func (bc *benchmarkClient) doCloseLoopUnary(conns []*grpc.ClientConn, rpcCountPe
 			bc.mutexes[idx] = new(sync.RWMutex)
 			bc.histograms[idx] = stats.NewHistogram(bc.histogramOptions)
 			// Start goroutine on the created mutex and histogram.
-			go func(mu *sync.RWMutex, histogram *stats.Histogram) {
+			go func(idx int) {
 				// TODO: do warm up if necessary.
 				// Now relying on worker client to reserve time to do warm up.
 				// The worker client needs to wait for some time after client is created,
@@ -252,9 +252,9 @@ func (bc *benchmarkClient) doCloseLoopUnary(conns []*grpc.ClientConn, rpcCountPe
 							return
 						}
 						elapse := time.Since(start)
-						mu.Lock()
-						histogram.Add(int64(elapse))
-						mu.Unlock()
+						bc.mutexes[idx].Lock()
+						bc.histograms[idx].Add(int64(elapse))
+						bc.mutexes[idx].Unlock()
 						select {
 						case <-bc.stop:
 						case done <- true:
@@ -266,7 +266,7 @@ func (bc *benchmarkClient) doCloseLoopUnary(conns []*grpc.ClientConn, rpcCountPe
 					case <-done:
 					}
 				}
-			}(bc.mutexes[idx], bc.histograms[idx])
+			}(idx)
 		}
 	}
 }
@@ -291,7 +291,7 @@ func (bc *benchmarkClient) doCloseLoopStreaming(conns []*grpc.ClientConn, rpcCou
 			bc.mutexes[idx] = new(sync.RWMutex)
 			bc.histograms[idx] = stats.NewHistogram(bc.histogramOptions)
 			// Start goroutine on the created mutex and histogram.
-			go func(mu *sync.RWMutex, histogram *stats.Histogram) {
+			go func(idx int) {
 				// TODO: do warm up if necessary.
 				// Now relying on worker client to reserve time to do warm up.
 				// The worker client needs to wait for some time after client is created,
@@ -308,9 +308,9 @@ func (bc *benchmarkClient) doCloseLoopStreaming(conns []*grpc.ClientConn, rpcCou
 							return
 						}
 						elapse := time.Since(start)
-						mu.Lock()
-						histogram.Add(int64(elapse))
-						mu.Unlock()
+						bc.mutexes[idx].Lock()
+						bc.histograms[idx].Add(int64(elapse))
+						bc.mutexes[idx].Unlock()
 						select {
 						case <-bc.stop:
 						case done <- true:
@@ -322,7 +322,7 @@ func (bc *benchmarkClient) doCloseLoopStreaming(conns []*grpc.ClientConn, rpcCou
 					case <-done:
 					}
 				}
-			}(bc.mutexes[idx], bc.histograms[idx])
+			}(idx)
 		}
 	}
 }
@@ -330,20 +330,32 @@ func (bc *benchmarkClient) doCloseLoopStreaming(conns []*grpc.ClientConn, rpcCou
 func (bc *benchmarkClient) getStats() *testpb.ClientStats {
 	timeElapsed := time.Since(bc.lastResetTime).Seconds()
 
-	// TODO merge histograms.
-	b := make([]uint32, len(bc.histograms[0].Buckets))
-	var totalcount int64
-	for _, h := range bc.histograms {
-		totalcount += h.Count
+	// Merging histogram may take some time.
+	// Put all histograms aside and merge later.
+	toMerge := make([]*stats.Histogram, len(bc.histograms))
+	for i := range bc.histograms {
+		bc.mutexes[i].Lock()
+		toMerge[i] = bc.histograms[i]
+		bc.histograms[i] = stats.NewHistogram(bc.histogramOptions)
+		bc.mutexes[i].Unlock()
+	}
+
+	for i := 1; i < len(toMerge); i++ {
+		toMerge[0].Merge(toMerge[i])
+	}
+
+	b := make([]uint32, len(toMerge[0].Buckets))
+	for i, v := range toMerge[0].Buckets {
+		b[i] = uint32(v.Count)
 	}
 	return &testpb.ClientStats{
 		Latencies: &testpb.HistogramData{
 			Bucket:       b,
-			MinSeen:      float64(bc.histograms[0].Min),
-			MaxSeen:      float64(bc.histograms[0].Max),
-			Sum:          float64(bc.histograms[0].Sum),
-			SumOfSquares: float64(bc.histograms[0].SumOfSquares),
-			Count:        float64(totalcount),
+			MinSeen:      float64(toMerge[0].Min),
+			MaxSeen:      float64(toMerge[0].Max),
+			Sum:          float64(toMerge[0].Sum),
+			SumOfSquares: float64(toMerge[0].SumOfSquares),
+			Count:        float64(toMerge[0].Count),
 		},
 		TimeElapsed: timeElapsed,
 		TimeUser:    0,