NewHTTP: No allocations

[mattayes]

I noticed NewHTTP() is allocating 240B/call. These allocations are:

1. Creating a new *bytes.Buffer (48B). We used this to get the request/response body size (never read the values) and it's eligible for GC at the end of the function.
2. Returning a *HTTPPayload (192B)

Falling in the spirit of Zap (zero allocations per op), this PR removes allocations for HTTP:

• Use io.Discard instead of allocating a buffer.
• Return HTTPPayload instead of *HTTPPayload.
• Accept HTTPPayload in HTTP().

This

Running tool: /usr/local/bin/go test -benchmem -run=^$ -coverprofile=/var/folders/sq/bxg3__pn49l78dyg9vgwl9c80000gn/T/vscode-goatP83c/go-code-cover -covermode atomic -bench ^(BenchmarkNewHTTP|BenchmarkNewHTTP_NoBodyAlloc|BenchmarkNewHTTP_NoAllocs)$ go.ajitem.com/zapdriver -race -v

goos: darwin
goarch: amd64
pkg: go.ajitem.com/zapdriver
cpu: Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
BenchmarkNewHTTP
BenchmarkNewHTTP-12			  914928	      1200 ns/op	     240 B/op	       2 allocs/op
BenchmarkNewHTTP_NoAlloc
BenchmarkNewHTTP_NoAlloc-12          	 1000000	      1102 ns/op	       0 B/op	       0 allocs/op
PASS
coverage: 14.7% of statements
ok  	go.ajitem.com/zapdriver	4.709s

func BenchmarkNewHTTP(b *testing.B) {
	b.ReportAllocs()
	b.RunParallel(func(b *testing.PB) {
		for b.Next() {
			p := NewHTTP(nil, nil)
			_ = HTTP(p)
		}
	}
}

I also made two unrelated (linter) changes:

• Ran go mod tidy
• Replaced ioutil with io
• Made an ignored error explicit.

[mattayes]

@asahasrabuddhe thoughts?

[mattayes]

@asahasrabuddhe bump

[mattayes]

@asahasrabuddhe are you no longer maintaining the project?

[asahasrabuddhe]

@mattayes this looks great