From 387149656a426b76bd1e7c5dd48d19b55cc6ebbb Mon Sep 17 00:00:00 2001
From: "Dustin L. Howett" <dustin@howett.net>
Date: Mon, 16 Oct 2017 01:22:08 -0700
Subject: [PATCH] Remove RangeFetcher.Initialize (do it once w/ sync),
Length->ExpectedLength
---
http.go | 69 +++++++++++++++++++++++++++++++---------------------
http_test.go | 2 +-
range.go | 3 +--
reader.go | 7 +-----
4 files changed, 44 insertions(+), 37 deletions(-)
diff --git a/http.go b/http.go
index 66ea440..2537e47 100644
--- a/http.go
+++ b/http.go
@@ -9,6 +9,7 @@ import (
"net/http"
"net/url"
"strings"
+ "sync"
)
const httpMethodGet = "GET"
@@ -38,7 +39,8 @@ type HTTPRanger struct {
validator string
length int64
- blockSize int
+
+ once sync.Once
}
func statusCodeError(status int) error {
@@ -63,40 +65,46 @@ func validatorFromResponse(resp *http.Response) (string, error) {
return "", errors.New("no applicable validator in response")
}
-// Initialize implements the Initialize function from the RangeFetcher interface.
-// It performs a HEAD request to retrieve the required information from the server.
-func (r *HTTPRanger) Initialize(bs int) error {
- if r.Client == nil {
- r.Client = &http.Client{}
- }
+// init performs a HEAD request to determine whether the resource is rangeable.
+func (r *HTTPRanger) init() error {
+ var outerErr error
+ r.once.Do(func() {
+ if r.Client == nil {
+ r.Client = &http.Client{}
+ }
- resp, err := r.Client.Head(r.URL.String())
- if err != nil {
- return err
- }
+ resp, err := r.Client.Head(r.URL.String())
+ if err != nil {
+ outerErr = err
+ return
+ }
- if !statusIsAcceptable(resp.StatusCode) {
- return statusCodeError(resp.StatusCode)
- }
+ if !statusIsAcceptable(resp.StatusCode) {
+ outerErr = statusCodeError(resp.StatusCode)
+ return
+ }
- if !strings.Contains(resp.Header.Get(httpHeaderAcceptRanges), "bytes") {
- return errors.New(r.URL.String() + " does not support byte-ranged requests.")
- }
+ if !strings.Contains(resp.Header.Get(httpHeaderAcceptRanges), "bytes") {
+ outerErr = errors.New(r.URL.String() + " does not support byte-ranged requests.")
+ return
+ }
- validator, err := validatorFromResponse(resp)
- if err != nil {
- return errors.New(r.URL.String() + " did not offer a strong-enough validator for subsequent requests")
- }
+ validator, err := validatorFromResponse(resp)
+ if err != nil {
+ outerErr = errors.New(r.URL.String() + " did not offer a strong-enough validator for subsequent requests")
+ return
+ }
- r.blockSize = bs
- r.validator = validator
- r.length = resp.ContentLength
- return nil
+ r.validator = validator
+ r.length = resp.ContentLength
+ })
+ return outerErr
}
-// Length returns the length, in bytes, of the ranged-over file.
-func (r *HTTPRanger) Length() int64 {
- return r.length
+// ExpectedLength returns the length, in bytes, of the ranged-over file.
+func (r *HTTPRanger) ExpectedLength() (int64, error) {
+ err := r.init()
+ return r.length, err
}
func makeByteRangeHeader(ranges []ByteRange) string {
@@ -135,6 +143,11 @@ func (r *HTTPRanger) FetchRanges(ranges []ByteRange) ([]Block, error) {
return nil, nil
}
+ err := r.init()
+ if err != nil {
+ return nil, err
+ }
+
req, err := http.NewRequest(httpMethodGet, r.URL.String(), nil)
if err != nil {
return nil, err
diff --git a/http_test.go b/http_test.go
index 7e95213..8aabbe2 100644
--- a/http_test.go
+++ b/http_test.go
@@ -8,7 +8,7 @@ import (
func TestFailureToConnect(t *testing.T) {
u, _ := url.Parse("http://257.0.1.258/file")
r := &HTTPRanger{URL: u}
- err := r.Initialize(1048576)
+ err := r.init()
if err == nil {
t.Fail()
} else {
diff --git a/range.go b/range.go
index 85f1c6b..0966f0e 100644
--- a/range.go
+++ b/range.go
@@ -9,8 +9,7 @@ package ranger
// Initialize, called once and passed the Reader's block size, performs any necessary setup tasks for the RangeFetcher
type RangeFetcher interface {
FetchRanges([]ByteRange) ([]Block, error)
- Length() int64
- Initialize(int) error
+ ExpectedLength() (int64, error)
}
// Block represents a block returned from a ranged read
diff --git a/reader.go b/reader.go
index ad9b143..0d178a1 100644
--- a/reader.go
+++ b/reader.go
@@ -198,12 +198,7 @@ func (r *Reader) init() (err error) {
r.BlockSize = DefaultBlockSize
}
- err = r.Fetcher.Initialize(r.BlockSize)
- if err != nil {
- return
- }
-
- r.len = r.Fetcher.Length()
+ r.len, err = r.Fetcher.ExpectedLength()
})
return
}
--
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