Benchmark across Parse options, add memory benchmarking. (#264)

This change updates the Parse benchmark to operate across useful ParseOptions, adds memory benchmarking, and updates some benchmark params. 

For example, we can take a look at the CPU / memory differences across the new ParseOptions for one of the test dicoms:
```
BenchmarkParse/NoOptions/4.dcm-4                                     	      10	 106876945 ns/op	120572543 B/op	    2160 allocs/op
BenchmarkParse/SkipPixelData/4.dcm-4                                 	      10	    531193 ns/op	   34900 B/op	    2144 allocs/op
BenchmarkParse/SkipProcessingPixelDataValue/4.dcm-4                  	      10	   1807256 ns/op	 7573518 B/op	    2146 allocs/op
```

.github/workflows/bench_pr.yml

@@ -25,11 +25,11 @@ jobs:
        go install golang.org/x/perf/cmd/benchstat@latest
        echo "New Commit:"
        git log -1 --format="%H"
-       go test -bench=. -benchtime=.75s -count=8 > $HOME/new.txt
+       go test -bench=. -benchmem -benchtime=10x -count=7 > $HOME/new.txt
        git reset --hard HEAD
        git checkout $GITHUB_BASE_REF
        echo "Base Commit:"
        git log -1 --format="%H"
-       go test -bench=. -benchtime=.75s -count=8 > $HOME/old.txt
+       go test -bench=. -benchmem -benchtime=10x -count=7 > $HOME/old.txt
        $GOBIN/benchstat $HOME/old.txt $HOME/new.txt
        

.github/workflows/bench_push.yml

@@ -25,10 +25,10 @@ jobs:
        go install golang.org/x/perf/cmd/benchstat@latest
        echo "New Commit:"
        git log -1 --format="%H"
-       go test -bench=. -benchtime=.75s -count=8 > $HOME/new.txt
+       go test -bench=. -benchmem -benchtime=10x -count=7 > $HOME/new.txt
        git reset --hard HEAD
        git checkout HEAD~1
        echo "Base Commit:"
        git log -1 --format="%H"
-       go test -bench=. -benchtime=.75s -count=8 > $HOME/old.txt
+       go test -bench=. -benchmem -benchtime=10x -count=7 > $HOME/old.txt
        $GOBIN/benchstat $HOME/old.txt $HOME/new.txt

Makefile

@@ -36,9 +36,13 @@ release:
 	tar -zcvf ${BINARY}-darwin-amd64.tar.gz ${BINARY}-darwin-amd64; \
 	zip -r ${BINARY}-windows-amd64.exe.zip ${BINARY}-windows-amd64.exe;
 
+.PHONY: bench
+bench:
+	go test -bench . -benchmem -benchtime=10x 
+
 bench-diff:
-	go test -bench . -benchtime=50x -count 5 > bench_current.txt
+	go test -bench . -benchmem -benchtime=10x -count 5 > bench_current.txt
 	git checkout main
-	go test -bench . -benchtime=50x -count 5 > bench_main.txt
+	go test -bench . -benchmem -benchtime=10x -count 5 > bench_main.txt
 	benchstat bench_main.txt bench_current.txt
 	git checkout -

parse_test.go

@@ -153,30 +153,53 @@ func TestParseFile_SkipProcessingPixelDataValue(t *testing.T) {
 
 // BenchmarkParse runs sanity benchmarks over the sample files in testdata.
 func BenchmarkParse(b *testing.B) {
-	files, err := ioutil.ReadDir("./testdata")
-	if err != nil {
-		b.Fatalf("unable to read testdata/: %v", err)
+	cases := []struct {
+		name string
+		opts []dicom.ParseOption
+	}{
+		{
+			name: "NoOptions",
+		},
+		{
+			name: "SkipPixelData",
+			opts: []dicom.ParseOption{dicom.SkipPixelData()},
+		},
+		{
+			name: "SkipProcessingPixelDataValue",
+			opts: []dicom.ParseOption{dicom.SkipProcessingPixelDataValue()},
+		},
 	}
-	for _, f := range files {
-		if !f.IsDir() && strings.HasSuffix(f.Name(), ".dcm") {
-			b.Run(f.Name(), func(b *testing.B) {
-				dcm, err := os.Open("./testdata/" + f.Name())
-				if err != nil {
-					b.Errorf("Unable to open %s. Error: %v", f.Name(), err)
-				}
-				defer dcm.Close()
+	for _, tc := range cases {
+		b.Run(tc.name, func(b *testing.B) {
+			files, err := ioutil.ReadDir("./testdata")
+			if err != nil {
+				b.Fatalf("unable to read testdata/: %v", err)
+			}
+			for _, f := range files {
+				if !f.IsDir() && strings.HasSuffix(f.Name(), ".dcm") {
+					b.Run(f.Name(), func(b *testing.B) {
 
-				data, err := ioutil.ReadAll(dcm)
-				if err != nil {
-					b.Errorf("Unable to read file into memory for benchmark: %v", err)
-				}
+						dcm, err := os.Open("./testdata/" + f.Name())
+						if err != nil {
+							b.Errorf("Unable to open %s. Error: %v", f.Name(), err)
+						}
+						defer dcm.Close()
+
+						data, err := ioutil.ReadAll(dcm)
+						if err != nil {
+							b.Errorf("Unable to read file into memory for benchmark: %v", err)
+						}
+
+						b.ResetTimer()
+
+						for i := 0; i < b.N; i++ {
+							_, _ = dicom.Parse(bytes.NewBuffer(data), int64(len(data)), nil, tc.opts...)
+						}
 
-				b.ResetTimer()
-				for i := 0; i < b.N; i++ {
-					_, _ = dicom.Parse(bytes.NewBuffer(data), int64(len(data)), nil)
+					})
 				}
-			})
-		}
+			}
+		})
 	}
 }