lib/http: refactoring Range request, limit content served by server

When server receive,

	GET /big
	Range: bytes=0-

and the requested resources is quite larger, where writing all content of
file result in i/o timeout, it is best practice [1][2] if the server
write only partial content and let the client continue with the
subsequent Range request.

In the above case, the server should response with,

	HTTP/1.1 206 Partial content
	Content-Range: bytes 0-<limit>/<size>
	Content-Length: <limit>

Where limit is maximum packet that is reasonable [3] for most of the
client.
In this server we choose 8MB as limit.

[1]: https://stackoverflow.com/questions/63614008/how-best-to-respond-to-an-open-http-range-request
[2]: https://bugzilla.mozilla.org/show_bug.cgi?id=570755
[3]: https://docs.aws.amazon.com/whitepapers/latest/s3-optimizing-performance-best-practices/use-byte-range-fetches.html

1 files changed, 4 insertions, 20 deletions

diff --git a/lib/http/range_position_example_test.go b/lib/http/range_position_example_test.go
index 927a6627..1b333565 100644
--- a/lib/http/range_position_example_test.go
+++ b/lib/http/range_position_example_test.go
@@ -7,35 +7,19 @@ import (
 )
 
 func ExampleParseContentRange() {
-	fmt.Println(libhttp.ParseContentRange(`bytes 10-/20`))   // OK
+	fmt.Println(libhttp.ParseContentRange(`bytes 10-/20`))   // Invalid, missing end.
 	fmt.Println(libhttp.ParseContentRange(`bytes 10-19/20`)) // OK
-	fmt.Println(libhttp.ParseContentRange(`bytes -10/20`))   // OK
+	fmt.Println(libhttp.ParseContentRange(`bytes -10/20`))   // Invalid, missing start.
 	fmt.Println(libhttp.ParseContentRange(`10-20/20`))       // Invalid, missing unit.
 	fmt.Println(libhttp.ParseContentRange(`bytes 10-`))      // Invalid, missing "/size".
 	fmt.Println(libhttp.ParseContentRange(`bytes -10/x`))    // Invalid, invalid "size".
 	fmt.Println(libhttp.ParseContentRange(`bytes`))          // Invalid, missing position.
 	// Output:
-	// 10-
+	// <nil>
 	// 10-19
-	// -10
 	// <nil>
 	// <nil>
 	// <nil>
 	// <nil>
-}
-
-func ExampleRangePosition_ContentRange() {
-	var (
-		unit = libhttp.AcceptRangesBytes
-		pos  = libhttp.RangePosition{
-			Start: 10,
-			End:   20,
-		}
-	)
-
-	fmt.Println(pos.ContentRange(unit, 512))
-	fmt.Println(pos.ContentRange(unit, 0))
-	// Output:
-	// bytes 10-20/512
-	// bytes 10-20/*
+	// <nil>
 }