From d560ab020a802fd898f83d3bdb1466703848fd3e Mon Sep 17 00:00:00 2001
From: Tim Raymond <tim@timraymond.com>
Date: Tue, 22 Aug 2017 10:23:24 -0400
Subject: [PATCH] Improve benchmark, fix offset bug

This ensures that setup time does not impact the results of the
benchmark since profiling showed that much time was spent setting up the
test array of tasks. This also uses `make` to build that slice instead.

Also, the tests revealed that there was a bug where offsets were
pre-incremented rather than post-incremented, omitting the first 100
results.
---
 kapacitor/kapa_client.go                |  2 +-
 kapacitor/kapa_client_benchmark_test.go | 23 ++++++++++++++---------
 kapacitor/kapa_client_test.go           |  4 ++++
 3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/kapacitor/kapa_client.go b/kapacitor/kapa_client.go
index 31f51bc96..f0d6c9e48 100644
--- a/kapacitor/kapa_client.go
+++ b/kapacitor/kapa_client.go
@@ -51,7 +51,6 @@ func (p *PaginatingKapaClient) ListTasks(opts *client.ListTasksOptions) ([]clien
 		}
 
 		for {
-			opts.Offset = p.FetchRate + opts.Offset
 			select {
 			case <-done:
 				close(optChan)
@@ -59,6 +58,7 @@ func (p *PaginatingKapaClient) ListTasks(opts *client.ListTasksOptions) ([]clien
 			case optChan <- *opts:
 				// nop
 			}
+			opts.Offset = p.FetchRate + opts.Offset
 		}
 	}()
 
diff --git a/kapacitor/kapa_client_benchmark_test.go b/kapacitor/kapa_client_benchmark_test.go
index 83bb88028..bca4cbebb 100644
--- a/kapacitor/kapa_client_benchmark_test.go
+++ b/kapacitor/kapa_client_benchmark_test.go
@@ -8,21 +8,23 @@ import (
 	client "github.com/influxdata/kapacitor/client/v1"
 )
 
-func BenchmarkKapaClient100(b *testing.B)   { benchmark_PaginatingKapaClient(100, b) }
-func BenchmarkKapaClient1000(b *testing.B)  { benchmark_PaginatingKapaClient(1000, b) }
-func BenchmarkKapaClient10000(b *testing.B) { benchmark_PaginatingKapaClient(10000, b) }
+func BenchmarkKapaClient100(b *testing.B)    { benchmark_PaginatingKapaClient(100, b) }
+func BenchmarkKapaClient1000(b *testing.B)   { benchmark_PaginatingKapaClient(1000, b) }
+func BenchmarkKapaClient10000(b *testing.B)  { benchmark_PaginatingKapaClient(10000, b) }
+func BenchmarkKapaClient100000(b *testing.B) { benchmark_PaginatingKapaClient(100000, b) }
+
+var tasks []client.Task
 
 func benchmark_PaginatingKapaClient(taskCount int, b *testing.B) {
+
+	b.StopTimer() // eliminate setup time
+
 	// create a mock client that will return a huge response from ListTasks
 	mockClient := &mocks.KapaClient{
 		ListTasksF: func(opts *client.ListTasksOptions) ([]client.Task, error) {
 			// create all the tasks
-			allTasks := []client.Task{}
+			allTasks := make([]client.Task, taskCount)
 
-			// create N tasks from the benchmark runner
-			for i := 0; i < taskCount; i++ {
-				allTasks = append(allTasks, client.Task{})
-			}
 			begin := opts.Offset
 			end := opts.Offset + opts.Limit
 
@@ -42,8 +44,11 @@ func benchmark_PaginatingKapaClient(taskCount int, b *testing.B) {
 
 	opts := &client.ListTasksOptions{}
 
+	b.StartTimer() // eliminate setup time
+
 	// let the benchmark runner run ListTasks until it's satisfied
 	for n := 0; n < b.N; n++ {
-		_, _ = pkap.ListTasks(opts)
+		// assignment is to avoid having the call optimized away
+		tasks, _ = pkap.ListTasks(opts)
 	}
 }
diff --git a/kapacitor/kapa_client_test.go b/kapacitor/kapa_client_test.go
index 63e1546ec..9dda521e5 100644
--- a/kapacitor/kapa_client_test.go
+++ b/kapacitor/kapa_client_test.go
@@ -26,6 +26,10 @@ func Test_Kapacitor_PaginatingKapaClient(t *testing.T) {
 				end = len(allTasks)
 			}
 
+			if begin > len(allTasks) {
+				begin = end
+			}
+
 			return allTasks[begin:end], nil
 		},
 	}