vendor/git.autistici.org/ai3/tools/replds/go.mod

@@ -3,9 +3,9 @@ module git.autistici.org/ai3/tools/replds
 go 1.14
 
 require (
-	git.autistici.org/ai3/go-common v0.0.0-20210110180225-a05c683cfe23
-	github.com/coreos/go-systemd/v22 v22.1.0
+	git.autistici.org/ai3/go-common v0.0.0-20220814151247-39e01d32d5ee
+	github.com/coreos/go-systemd/v22 v22.3.2
 	github.com/google/subcommands v1.2.0
-	github.com/prometheus/client_golang v1.9.0
-	gopkg.in/yaml.v2 v2.4.0
+	github.com/prometheus/client_golang v1.12.2
+	gopkg.in/yaml.v3 v3.0.1
 )

vendor/github.com/NYTimes/gziphandler/.gitignore

+*.swp

vendor/github.com/NYTimes/gziphandler/.travis.yml

+language: go
+go:
+  - 1.x
+  - tip
+env:
+  - GO111MODULE=on
+install:
+  - go mod download
+script:
+  - go test -race -v

vendor/github.com/NYTimes/gziphandler/CODE_OF_CONDUCT.md

+---
+layout: code-of-conduct
+version: v1.0
+---
+
+This code of conduct outlines our expectations for participants within the **NYTimes/gziphandler** community, as well as steps to reporting unacceptable behavior. We are committed to providing a welcoming and inspiring community for all and expect our code of conduct to be honored. Anyone who violates this code of conduct may be banned from the community.
+
+Our open source community strives to:
+
+* **Be friendly and patient.**
+* **Be welcoming**: We strive to be a community that welcomes and supports people of all backgrounds and identities. This includes, but is not limited to members of any race, ethnicity, culture, national origin, colour, immigration status, social and economic class, educational level, sex, sexual orientation, gender identity and expression, age, size, family status, political belief, religion, and mental and physical ability.
+* **Be considerate**: Your work will be used by other people, and you in turn will depend on the work of others. Any decision you take will affect users and colleagues, and you should take those consequences into account when making decisions. Remember that we're a world-wide community, so you might not be communicating in someone else's primary language.
+* **Be respectful**:  Not all of us will agree all the time, but disagreement is no excuse for poor behavior and poor manners. We might all experience some frustration now and then, but we cannot allow that frustration to turn into a personal attack. It’s important to remember that a community where people feel uncomfortable or threatened is not a productive one.
+* **Be careful in the words that we choose**: we are a community of professionals, and we conduct ourselves professionally. Be kind to others. Do not insult or put down other participants. Harassment and other exclusionary behavior aren't acceptable.
+* **Try to understand why we disagree**: Disagreements, both social and technical, happen all the time. It is important that we resolve disagreements and differing views constructively. Remember that we’re different. The strength of our community comes from its diversity, people from a wide range of backgrounds. Different people have different perspectives on issues. Being unable to understand why someone holds a viewpoint doesn’t mean that they’re wrong. Don’t forget that it is human to err and blaming each other doesn’t get us anywhere. Instead, focus on helping to resolve issues and learning from mistakes.
+
+## Definitions
+
+Harassment includes, but is not limited to:
+
+- Offensive comments related to gender, gender identity and expression, sexual orientation, disability, mental illness, neuro(a)typicality, physical appearance, body size, race, age, regional discrimination, political or religious affiliation
+- Unwelcome comments regarding a person’s lifestyle choices and practices, including those related to food, health, parenting, drugs, and employment
+- Deliberate misgendering. This includes deadnaming or persistently using a pronoun that does not correctly reflect a person's gender identity. You must address people by the name they give you when not addressing them by their username or handle
+- Physical contact and simulated physical contact (eg, textual descriptions like “*hug*” or “*backrub*”) without consent or after a request to stop
+- Threats of violence, both physical and psychological
+- Incitement of violence towards any individual, including encouraging a person to commit suicide or to engage in self-harm
+- Deliberate intimidation
+- Stalking or following
+- Harassing photography or recording, including logging online activity for harassment purposes
+- Sustained disruption of discussion
+- Unwelcome sexual attention, including gratuitous or off-topic sexual images or behaviour
+- Pattern of inappropriate social contact, such as requesting/assuming inappropriate levels of intimacy with others
+- Continued one-on-one communication after requests to cease
+- Deliberate “outing” of any aspect of a person’s identity without their consent except as necessary to protect others from intentional abuse
+- Publication of non-harassing private communication
+
+Our open source community prioritizes marginalized people’s safety over privileged people’s comfort. We will not act on complaints regarding:
+
+- ‘Reverse’ -isms, including ‘reverse racism,’ ‘reverse sexism,’ and ‘cisphobia’
+- Reasonable communication of boundaries, such as “leave me alone,” “go away,” or “I’m not discussing this with you”
+- Refusal to explain or debate social justice concepts
+- Communicating in a ‘tone’ you don’t find congenial
+- Criticizing racist, sexist, cissexist, or otherwise oppressive behavior or assumptions
+
+
+### Diversity Statement
+
+We encourage everyone to participate and are committed to building a community for all. Although we will fail at times, we seek to treat everyone both as fairly and equally as possible. Whenever a participant has made a mistake, we expect them to take responsibility for it. If someone has been harmed or offended, it is our responsibility to listen carefully and respectfully, and do our best to right the wrong.
+
+Although this list cannot be exhaustive, we explicitly honor diversity in age, gender, gender identity or expression, culture, ethnicity, language, national origin, political beliefs, profession, race, religion, sexual orientation, socioeconomic status, and technical ability. We will not tolerate discrimination based on any of the protected
+characteristics above, including participants with disabilities.
+
+### Reporting Issues
+
+If you experience or witness unacceptable behavior—or have any other concerns—please report it by contacting us via **code@nytimes.com**. All reports will be handled with discretion. In your report please include:
+
+- Your contact information.
+- Names (real, nicknames, or pseudonyms) of any individuals involved. If there are additional witnesses, please
+include them as well. Your account of what occurred, and if you believe the incident is ongoing. If there is a publicly available record (e.g. a mailing list archive or a public IRC logger), please include a link.
+- Any additional information that may be helpful.
+
+After filing a report, a representative will contact you personally, review the incident, follow up with any additional questions, and make a decision as to how to respond. If the person who is harassing you is part of the response team, they will recuse themselves from handling your incident. If the complaint originates from a member of the response team, it will be handled by a different member of the response team. We will respect confidentiality requests for the purpose of protecting victims of abuse.
+
+### Attribution & Acknowledgements
+
+We all stand on the shoulders of giants across many open source communities.  We'd like to thank the communities and projects that established code of conducts and diversity statements as our inspiration:
+
+* [Django](https://www.djangoproject.com/conduct/reporting/)
+* [Python](https://www.python.org/community/diversity/)
+* [Ubuntu](http://www.ubuntu.com/about/about-ubuntu/conduct)
+* [Contributor Covenant](http://contributor-covenant.org/)
+* [Geek Feminism](http://geekfeminism.org/about/code-of-conduct/)
+* [Citizen Code of Conduct](http://citizencodeofconduct.org/)
+
+This Code of Conduct was based on https://github.com/todogroup/opencodeofconduct

vendor/github.com/NYTimes/gziphandler/CONTRIBUTING.md

+# Contributing to NYTimes/gziphandler
+
+This is an open source project started by handful of developers at The New York Times and open to the entire Go community.
+
+We really appreciate your help!
+
+## Filing issues
+
+When filing an issue, make sure to answer these five questions:
+
+1. What version of Go are you using (`go version`)?
+2. What operating system and processor architecture are you using?
+3. What did you do?
+4. What did you expect to see?
+5. What did you see instead?
+
+## Contributing code
+
+Before submitting changes, please follow these guidelines:
+
+1. Check the open issues and pull requests for existing discussions.
+2. Open an issue to discuss a new feature.
+3. Write tests.
+4. Make sure code follows the ['Go Code Review Comments'](https://github.com/golang/go/wiki/CodeReviewComments).
+5. Make sure your changes pass `go test`.
+6. Make sure the entire test suite passes locally and on Travis CI.
+7. Open a Pull Request.
+8. [Squash your commits](http://gitready.com/advanced/2009/02/10/squashing-commits-with-rebase.html) after receiving feedback and add a [great commit message](http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html).
+
+Unless otherwise noted, the gziphandler source files are distributed under the Apache 2.0-style license found in the LICENSE.md file.

vendor/github.com/NYTimes/gziphandler/LICENSE

+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright 2016-2017 The New York Times Company
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

vendor/github.com/NYTimes/gziphandler/README.md

+Gzip Handler
+============
+
+This is a tiny Go package which wraps HTTP handlers to transparently gzip the
+response body, for clients which support it. Although it's usually simpler to
+leave that to a reverse proxy (like nginx or Varnish), this package is useful
+when that's undesirable.
+
+## Install
+```bash
+go get -u github.com/NYTimes/gziphandler
+```
+
+## Usage
+
+Call `GzipHandler` with any handler (an object which implements the
+`http.Handler` interface), and it'll return a new handler which gzips the
+response. For example:
+
+```go
+package main
+
+import (
+	"io"
+	"net/http"
+	"github.com/NYTimes/gziphandler"
+)
+
+func main() {
+	withoutGz := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/plain")
+		io.WriteString(w, "Hello, World")
+	})
+
+	withGz := gziphandler.GzipHandler(withoutGz)
+
+	http.Handle("/", withGz)
+	http.ListenAndServe("0.0.0.0:8000", nil)
+}
+```
+
+
+## Documentation
+
+The docs can be found at [godoc.org][docs], as usual.
+
+
+## License
+
+[Apache 2.0][license].
+
+
+
+
+[docs]:     https://godoc.org/github.com/NYTimes/gziphandler
+[license]:  https://github.com/NYTimes/gziphandler/blob/master/LICENSE

vendor/github.com/NYTimes/gziphandler/go.mod

+module github.com/NYTimes/gziphandler
+
+go 1.11
+
+require github.com/stretchr/testify v1.3.0

vendor/github.com/NYTimes/gziphandler/go.sum

+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=

vendor/github.com/NYTimes/gziphandler/gzip.go

+package gziphandler // import "github.com/NYTimes/gziphandler"
+
+import (
+	"bufio"
+	"compress/gzip"
+	"fmt"
+	"io"
+	"mime"
+	"net"
+	"net/http"
+	"strconv"
+	"strings"
+	"sync"
+)
+
+const (
+	vary            = "Vary"
+	acceptEncoding  = "Accept-Encoding"
+	contentEncoding = "Content-Encoding"
+	contentType     = "Content-Type"
+	contentLength   = "Content-Length"
+)
+
+type codings map[string]float64
+
+const (
+	// DefaultQValue is the default qvalue to assign to an encoding if no explicit qvalue is set.
+	// This is actually kind of ambiguous in RFC 2616, so hopefully it's correct.
+	// The examples seem to indicate that it is.
+	DefaultQValue = 1.0
+
+	// DefaultMinSize is the default minimum size until we enable gzip compression.
+	// 1500 bytes is the MTU size for the internet since that is the largest size allowed at the network layer.
+	// If you take a file that is 1300 bytes and compress it to 800 bytes, it’s still transmitted in that same 1500 byte packet regardless, so you’ve gained nothing.
+	// That being the case, you should restrict the gzip compression to files with a size greater than a single packet, 1400 bytes (1.4KB) is a safe value.
+	DefaultMinSize = 1400
+)
+
+// gzipWriterPools stores a sync.Pool for each compression level for reuse of
+// gzip.Writers. Use poolIndex to covert a compression level to an index into
+// gzipWriterPools.
+var gzipWriterPools [gzip.BestCompression - gzip.BestSpeed + 2]*sync.Pool
+
+func init() {
+	for i := gzip.BestSpeed; i <= gzip.BestCompression; i++ {
+		addLevelPool(i)
+	}
+	addLevelPool(gzip.DefaultCompression)
+}
+
+// poolIndex maps a compression level to its index into gzipWriterPools. It
+// assumes that level is a valid gzip compression level.
+func poolIndex(level int) int {
+	// gzip.DefaultCompression == -1, so we need to treat it special.
+	if level == gzip.DefaultCompression {
+		return gzip.BestCompression - gzip.BestSpeed + 1
+	}
+	return level - gzip.BestSpeed
+}
+
+func addLevelPool(level int) {
+	gzipWriterPools[poolIndex(level)] = &sync.Pool{
+		New: func() interface{} {
+			// NewWriterLevel only returns error on a bad level, we are guaranteeing
+			// that this will be a valid level so it is okay to ignore the returned
+			// error.
+			w, _ := gzip.NewWriterLevel(nil, level)
+			return w
+		},
+	}
+}
+
+// GzipResponseWriter provides an http.ResponseWriter interface, which gzips
+// bytes before writing them to the underlying response. This doesn't close the
+// writers, so don't forget to do that.
+// It can be configured to skip response smaller than minSize.
+type GzipResponseWriter struct {
+	http.ResponseWriter
+	index int // Index for gzipWriterPools.
+	gw    *gzip.Writer
+
+	code int // Saves the WriteHeader value.
+
+	minSize int    // Specifed the minimum response size to gzip. If the response length is bigger than this value, it is compressed.
+	buf     []byte // Holds the first part of the write before reaching the minSize or the end of the write.
+	ignore  bool   // If true, then we immediately passthru writes to the underlying ResponseWriter.
+
+	contentTypes []parsedContentType // Only compress if the response is one of these content-types. All are accepted if empty.
+}
+
+type GzipResponseWriterWithCloseNotify struct {
+	*GzipResponseWriter
+}
+
+func (w GzipResponseWriterWithCloseNotify) CloseNotify() <-chan bool {
+	return w.ResponseWriter.(http.CloseNotifier).CloseNotify()
+}
+
+// Write appends data to the gzip writer.
+func (w *GzipResponseWriter) Write(b []byte) (int, error) {
+	// GZIP responseWriter is initialized. Use the GZIP responseWriter.
+	if w.gw != nil {
+		return w.gw.Write(b)
+	}
+
+	// If we have already decided not to use GZIP, immediately passthrough.
+	if w.ignore {
+		return w.ResponseWriter.Write(b)
+	}
+
+	// Save the write into a buffer for later use in GZIP responseWriter (if content is long enough) or at close with regular responseWriter.
+	// On the first write, w.buf changes from nil to a valid slice
+	w.buf = append(w.buf, b...)
+
+	var (
+		cl, _ = strconv.Atoi(w.Header().Get(contentLength))
+		ct    = w.Header().Get(contentType)
+		ce    = w.Header().Get(contentEncoding)
+	)
+	// Only continue if they didn't already choose an encoding or a known unhandled content length or type.
+	if ce == "" && (cl == 0 || cl >= w.minSize) && (ct == "" || handleContentType(w.contentTypes, ct)) {
+		// If the current buffer is less than minSize and a Content-Length isn't set, then wait until we have more data.
+		if len(w.buf) < w.minSize && cl == 0 {
+			return len(b), nil
+		}
+		// If the Content-Length is larger than minSize or the current buffer is larger than minSize, then continue.
+		if cl >= w.minSize || len(w.buf) >= w.minSize {
+			// If a Content-Type wasn't specified, infer it from the current buffer.
+			if ct == "" {
+				ct = http.DetectContentType(w.buf)
+				w.Header().Set(contentType, ct)
+			}
+			// If the Content-Type is acceptable to GZIP, initialize the GZIP writer.
+			if handleContentType(w.contentTypes, ct) {
+				if err := w.startGzip(); err != nil {
+					return 0, err
+				}
+				return len(b), nil
+			}
+		}
+	}
+	// If we got here, we should not GZIP this response.
+	if err := w.startPlain(); err != nil {
+		return 0, err
+	}
+	return len(b), nil
+}
+
+// startGzip initializes a GZIP writer and writes the buffer.
+func (w *GzipResponseWriter) startGzip() error {
+	// Set the GZIP header.
+	w.Header().Set(contentEncoding, "gzip")
+
+	// if the Content-Length is already set, then calls to Write on gzip
+	// will fail to set the Content-Length header since its already set
+	// See: https://github.com/golang/go/issues/14975.
+	w.Header().Del(contentLength)
+
+	// Write the header to gzip response.
+	if w.code != 0 {
+		w.ResponseWriter.WriteHeader(w.code)
+		// Ensure that no other WriteHeader's happen
+		w.code = 0
+	}
+
+	// Initialize and flush the buffer into the gzip response if there are any bytes.
+	// If there aren't any, we shouldn't initialize it yet because on Close it will
+	// write the gzip header even if nothing was ever written.
+	if len(w.buf) > 0 {
+		// Initialize the GZIP response.
+		w.init()
+		n, err := w.gw.Write(w.buf)
+
+		// This should never happen (per io.Writer docs), but if the write didn't
+		// accept the entire buffer but returned no specific error, we have no clue
+		// what's going on, so abort just to be safe.
+		if err == nil && n < len(w.buf) {
+			err = io.ErrShortWrite
+		}
+		return err
+	}
+	return nil
+}
+
+// startPlain writes to sent bytes and buffer the underlying ResponseWriter without gzip.
+func (w *GzipResponseWriter) startPlain() error {
+	if w.code != 0 {
+		w.ResponseWriter.WriteHeader(w.code)
+		// Ensure that no other WriteHeader's happen
+		w.code = 0
+	}
+	w.ignore = true
+	// If Write was never called then don't call Write on the underlying ResponseWriter.
+	if w.buf == nil {
+		return nil
+	}
+	n, err := w.ResponseWriter.Write(w.buf)
+	w.buf = nil
+	// This should never happen (per io.Writer docs), but if the write didn't
+	// accept the entire buffer but returned no specific error, we have no clue
+	// what's going on, so abort just to be safe.
+	if err == nil && n < len(w.buf) {
+		err = io.ErrShortWrite
+	}
+	return err
+}
+
+// WriteHeader just saves the response code until close or GZIP effective writes.
+func (w *GzipResponseWriter) WriteHeader(code int) {
+	if w.code == 0 {
+		w.code = code
+	}
+}
+
+// init graps a new gzip writer from the gzipWriterPool and writes the correct
+// content encoding header.
+func (w *GzipResponseWriter) init() {
+	// Bytes written during ServeHTTP are redirected to this gzip writer
+	// before being written to the underlying response.
+	gzw := gzipWriterPools[w.index].Get().(*gzip.Writer)
+	gzw.Reset(w.ResponseWriter)
+	w.gw = gzw
+}
+
+// Close will close the gzip.Writer and will put it back in the gzipWriterPool.
+func (w *GzipResponseWriter) Close() error {
+	if w.ignore {
+		return nil
+	}
+
+	if w.gw == nil {
+		// GZIP not triggered yet, write out regular response.
+		err := w.startPlain()
+		// Returns the error if any at write.
+		if err != nil {
+			err = fmt.Errorf("gziphandler: write to regular responseWriter at close gets error: %q", err.Error())
+		}
+		return err
+	}
+
+	err := w.gw.Close()
+	gzipWriterPools[w.index].Put(w.gw)
+	w.gw = nil
+	return err
+}
+
+// Flush flushes the underlying *gzip.Writer and then the underlying
+// http.ResponseWriter if it is an http.Flusher. This makes GzipResponseWriter
+// an http.Flusher.
+func (w *GzipResponseWriter) Flush() {
+	if w.gw == nil && !w.ignore {
+		// Only flush once startGzip or startPlain has been called.
+		//
+		// Flush is thus a no-op until we're certain whether a plain
+		// or gzipped response will be served.
+		return
+	}
+
+	if w.gw != nil {
+		w.gw.Flush()
+	}
+
+	if fw, ok := w.ResponseWriter.(http.Flusher); ok {
+		fw.Flush()
+	}
+}
+
+// Hijack implements http.Hijacker. If the underlying ResponseWriter is a
+// Hijacker, its Hijack method is returned. Otherwise an error is returned.
+func (w *GzipResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	if hj, ok := w.ResponseWriter.(http.Hijacker); ok {
+		return hj.Hijack()
+	}
+	return nil, nil, fmt.Errorf("http.Hijacker interface is not supported")
+}
+
+// verify Hijacker interface implementation
+var _ http.Hijacker = &GzipResponseWriter{}
+
+// MustNewGzipLevelHandler behaves just like NewGzipLevelHandler except that in
+// an error case it panics rather than returning an error.
+func MustNewGzipLevelHandler(level int) func(http.Handler) http.Handler {
+	wrap, err := NewGzipLevelHandler(level)
+	if err != nil {
+		panic(err)
+	}
+	return wrap
+}
+
+// NewGzipLevelHandler returns a wrapper function (often known as middleware)
+// which can be used to wrap an HTTP handler to transparently gzip the response
+// body if the client supports it (via the Accept-Encoding header). Responses will
+// be encoded at the given gzip compression level. An error will be returned only
+// if an invalid gzip compression level is given, so if one can ensure the level
+// is valid, the returned error can be safely ignored.
+func NewGzipLevelHandler(level int) (func(http.Handler) http.Handler, error) {
+	return NewGzipLevelAndMinSize(level, DefaultMinSize)
+}
+
+// NewGzipLevelAndMinSize behave as NewGzipLevelHandler except it let the caller
+// specify the minimum size before compression.
+func NewGzipLevelAndMinSize(level, minSize int) (func(http.Handler) http.Handler, error) {
+	return GzipHandlerWithOpts(CompressionLevel(level), MinSize(minSize))
+}
+
+func GzipHandlerWithOpts(opts ...option) (func(http.Handler) http.Handler, error) {
+	c := &config{
+		level:   gzip.DefaultCompression,
+		minSize: DefaultMinSize,
+	}
+
+	for _, o := range opts {
+		o(c)
+	}
+
+	if err := c.validate(); err != nil {
+		return nil, err
+	}
+
+	return func(h http.Handler) http.Handler {
+		index := poolIndex(c.level)
+
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Add(vary, acceptEncoding)
+			if acceptsGzip(r) {
+				gw := &GzipResponseWriter{
+					ResponseWriter: w,
+					index:          index,
+					minSize:        c.minSize,
+					contentTypes:   c.contentTypes,
+				}
+				defer gw.Close()
+
+				if _, ok := w.(http.CloseNotifier); ok {
+					gwcn := GzipResponseWriterWithCloseNotify{gw}
+					h.ServeHTTP(gwcn, r)
+				} else {
+					h.ServeHTTP(gw, r)
+				}
+
+			} else {
+				h.ServeHTTP(w, r)
+			}
+		})
+	}, nil
+}
+
+// Parsed representation of one of the inputs to ContentTypes.
+// See https://golang.org/pkg/mime/#ParseMediaType
+type parsedContentType struct {
+	mediaType string
+	params    map[string]string
+}
+
+// equals returns whether this content type matches another content type.
+func (pct parsedContentType) equals(mediaType string, params map[string]string) bool {
+	if pct.mediaType != mediaType {
+		return false
+	}
+	// if pct has no params, don't care about other's params
+	if len(pct.params) == 0 {
+		return true
+	}
+
+	// if pct has any params, they must be identical to other's.
+	if len(pct.params) != len(params) {
+		return false
+	}
+	for k, v := range pct.params {
+		if w, ok := params[k]; !ok || v != w {
+			return false
+		}
+	}
+	return true
+}
+
+// Used for functional configuration.
+type config struct {
+	minSize      int
+	level        int
+	contentTypes []parsedContentType
+}
+
+func (c *config) validate() error {
+	if c.level != gzip.DefaultCompression && (c.level < gzip.BestSpeed || c.level > gzip.BestCompression) {
+		return fmt.Errorf("invalid compression level requested: %d", c.level)
+	}
+
+	if c.minSize < 0 {
+		return fmt.Errorf("minimum size must be more than zero")
+	}
+
+	return nil
+}
+
+type option func(c *config)
+
+func MinSize(size int) option {
+	return func(c *config) {
+		c.minSize = size
+	}
+}
+
+func CompressionLevel(level int) option {
+	return func(c *config) {
+		c.level = level
+	}
+}
+
+// ContentTypes specifies a list of content types to compare
+// the Content-Type header to before compressing. If none
+// match, the response will be returned as-is.
+//
+// Content types are compared in a case-insensitive, whitespace-ignored
+// manner.
+//
+// A MIME type without any other directive will match a content type
+// that has the same MIME type, regardless of that content type's other
+// directives. I.e., "text/html" will match both "text/html" and
+// "text/html; charset=utf-8".
+//
+// A MIME type with any other directive will only match a content type
+// that has the same MIME type and other directives. I.e.,
+// "text/html; charset=utf-8" will only match "text/html; charset=utf-8".
+//
+// By default, responses are gzipped regardless of
+// Content-Type.
+func ContentTypes(types []string) option {
+	return func(c *config) {
+		c.contentTypes = []parsedContentType{}
+		for _, v := range types {
+			mediaType, params, err := mime.ParseMediaType(v)
+			if err == nil {
+				c.contentTypes = append(c.contentTypes, parsedContentType{mediaType, params})
+			}
+		}
+	}
+}
+
+// GzipHandler wraps an HTTP handler, to transparently gzip the response body if
+// the client supports it (via the Accept-Encoding header). This will compress at
+// the default compression level.
+func GzipHandler(h http.Handler) http.Handler {
+	wrapper, _ := NewGzipLevelHandler(gzip.DefaultCompression)
+	return wrapper(h)
+}
+
+// acceptsGzip returns true if the given HTTP request indicates that it will
+// accept a gzipped response.
+func acceptsGzip(r *http.Request) bool {
+	acceptedEncodings, _ := parseEncodings(r.Header.Get(acceptEncoding))
+	return acceptedEncodings["gzip"] > 0.0
+}
+
+// returns true if we've been configured to compress the specific content type.
+func handleContentType(contentTypes []parsedContentType, ct string) bool {
+	// If contentTypes is empty we handle all content types.
+	if len(contentTypes) == 0 {
+		return true
+	}
+
+	mediaType, params, err := mime.ParseMediaType(ct)
+	if err != nil {
+		return false
+	}
+
+	for _, c := range contentTypes {
+		if c.equals(mediaType, params) {
+			return true
+		}
+	}
+
+	return false
+}
+
+// parseEncodings attempts to parse a list of codings, per RFC 2616, as might
+// appear in an Accept-Encoding header. It returns a map of content-codings to
+// quality values, and an error containing the errors encountered. It's probably
+// safe to ignore those, because silently ignoring errors is how the internet
+// works.
+//
+// See: http://tools.ietf.org/html/rfc2616#section-14.3.
+func parseEncodings(s string) (codings, error) {
+	c := make(codings)
+	var e []string
+
+	for _, ss := range strings.Split(s, ",") {
+		coding, qvalue, err := parseCoding(ss)
+
+		if err != nil {
+			e = append(e, err.Error())
+		} else {
+			c[coding] = qvalue
+		}
+	}
+
+	// TODO (adammck): Use a proper multi-error struct, so the individual errors
+	//                 can be extracted if anyone cares.
+	if len(e) > 0 {
+		return c, fmt.Errorf("errors while parsing encodings: %s", strings.Join(e, ", "))
+	}
+
+	return c, nil
+}
+
+// parseCoding parses a single conding (content-coding with an optional qvalue),
+// as might appear in an Accept-Encoding header. It attempts to forgive minor
+// formatting errors.
+func parseCoding(s string) (coding string, qvalue float64, err error) {
+	for n, part := range strings.Split(s, ";") {
+		part = strings.TrimSpace(part)
+		qvalue = DefaultQValue
+
+		if n == 0 {
+			coding = strings.ToLower(part)
+		} else if strings.HasPrefix(part, "q=") {
+			qvalue, err = strconv.ParseFloat(strings.TrimPrefix(part, "q="), 64)
+
+			if qvalue < 0.0 {
+				qvalue = 0.0
+			} else if qvalue > 1.0 {
+				qvalue = 1.0
+			}
+		}
+	}
+
+	if coding == "" {
+		err = fmt.Errorf("empty content-coding")
+	}
+
+	return
+}

vendor/github.com/NYTimes/gziphandler/gzip_go18.go

+// +build go1.8
+
+package gziphandler
+
+import "net/http"
+
+// Push initiates an HTTP/2 server push.
+// Push returns ErrNotSupported if the client has disabled push or if push
+// is not supported on the underlying connection.
+func (w *GzipResponseWriter) Push(target string, opts *http.PushOptions) error {
+	pusher, ok := w.ResponseWriter.(http.Pusher)
+	if ok && pusher != nil {
+		return pusher.Push(target, setAcceptEncodingForPushOptions(opts))
+	}
+	return http.ErrNotSupported
+}
+
+// setAcceptEncodingForPushOptions sets "Accept-Encoding" : "gzip" for PushOptions without overriding existing headers.
+func setAcceptEncodingForPushOptions(opts *http.PushOptions) *http.PushOptions {
+
+	if opts == nil {
+		opts = &http.PushOptions{
+			Header: http.Header{
+				acceptEncoding: []string{"gzip"},
+			},
+		}
+		return opts
+	}
+
+	if opts.Header == nil {
+		opts.Header = http.Header{
+			acceptEncoding: []string{"gzip"},
+		}
+		return opts
+	}
+
+	if encoding := opts.Header.Get(acceptEncoding); encoding == "" {
+		opts.Header.Add(acceptEncoding, "gzip")
+		return opts
+	}
+
+	return opts
+}

vendor/github.com/cenkalti/backoff/v4/context.go

@@ -57,10 +57,6 @@ func (b *backOffContext) NextBackOff() time.Duration {
 	case <-b.ctx.Done():
 		return Stop
 	default:
+		return b.BackOff.NextBackOff()
 	}
-	next := b.BackOff.NextBackOff()
-	if deadline, ok := b.ctx.Deadline(); ok && deadline.Sub(time.Now()) < next { // nolint: gosimple
-		return Stop
-	}
-	return next
 }

vendor/github.com/cenkalti/backoff/v4/exponential.go

@@ -147,6 +147,9 @@ func (b *ExponentialBackOff) incrementCurrentInterval() {
 // Returns a random value from the following interval:
 // 	[currentInterval - randomizationFactor * currentInterval, currentInterval + randomizationFactor * currentInterval].
 func getRandomValueFromInterval(randomizationFactor, random float64, currentInterval time.Duration) time.Duration {
+	if randomizationFactor == 0 {
+		return currentInterval // make sure no randomness is used when randomizationFactor is 0.
+	}
 	var delta = randomizationFactor * float64(currentInterval)
 	var minInterval = float64(currentInterval) - delta
 	var maxInterval = float64(currentInterval) + delta

vendor/github.com/cenkalti/backoff/v4/retry.go

@@ -62,6 +62,10 @@ func RetryNotifyWithTimer(operation Operation, b BackOff, notify Notify, t Timer
 		}
 
 		if next = b.NextBackOff(); next == Stop {
+			if cerr := ctx.Err(); cerr != nil {
+				return cerr
+			}
+
 			return err
 		}
 

vendor/github.com/felixge/httpsnoop/README.md

@@ -65,7 +65,8 @@ being called, or called more than once, as well as concurrent calls to
 Unfortunately this package is not perfect either. It's possible that it is
 still missing some interfaces provided by the go core (let me know if you find
 one), and it won't work for applications adding their own interfaces into the
-mix.
+mix. You can however use `httpsnoop.Unwrap(w)` to access the underlying
+`http.ResponseWriter` and type-assert the result to its other interfaces.
 
 However, hopefully the explanation above has sufficiently scared you of rolling
 your own solution to this problem. httpsnoop may still break your application,

vendor/github.com/felixge/httpsnoop/capture_metrics.go

@@ -3,7 +3,6 @@ package httpsnoop
 import (
 	"io"
 	"net/http"
-	"sync"
 	"time"
 )
 
@@ -36,17 +35,23 @@ func CaptureMetrics(hnd http.Handler, w http.ResponseWriter, r *http.Request) Me
 // sugar on top of this func), but is a more usable interface if your
 // application doesn't use the Go http.Handler interface.
 func CaptureMetricsFn(w http.ResponseWriter, fn func(http.ResponseWriter)) Metrics {
+	m := Metrics{Code: http.StatusOK}
+	m.CaptureMetrics(w, fn)
+	return m
+}
+
+// CaptureMetrics wraps w and calls fn with the wrapped w and updates
+// Metrics m with the resulting metrics. This is similar to CaptureMetricsFn,
+// but allows one to customize starting Metrics object.
+func (m *Metrics) CaptureMetrics(w http.ResponseWriter, fn func(http.ResponseWriter)) {
 	var (
 		start         = time.Now()
-		m             = Metrics{Code: http.StatusOK}
 		headerWritten bool
-		lock          sync.Mutex
 		hooks         = Hooks{
 			WriteHeader: func(next WriteHeaderFunc) WriteHeaderFunc {
 				return func(code int) {
 					next(code)
-					lock.Lock()
-					defer lock.Unlock()
+
 					if !headerWritten {
 						m.Code = code
 						headerWritten = true
@@ -57,8 +62,7 @@ func CaptureMetricsFn(w http.ResponseWriter, fn func(http.ResponseWriter)) Metri
 			Write: func(next WriteFunc) WriteFunc {
 				return func(p []byte) (int, error) {
 					n, err := next(p)
-					lock.Lock()
-					defer lock.Unlock()
+
 					m.Written += int64(n)
 					headerWritten = true
 					return n, err
@@ -68,8 +72,7 @@ func CaptureMetricsFn(w http.ResponseWriter, fn func(http.ResponseWriter)) Metri
 			ReadFrom: func(next ReadFromFunc) ReadFromFunc {
 				return func(src io.Reader) (int64, error) {
 					n, err := next(src)
-					lock.Lock()
-					defer lock.Unlock()
+
 					headerWritten = true
 					m.Written += n
 					return n, err
@@ -79,6 +82,5 @@ func CaptureMetricsFn(w http.ResponseWriter, fn func(http.ResponseWriter)) Metri
 	)
 
 	fn(Wrap(w, hooks))
-	m.Duration = time.Since(start)
-	return m
+	m.Duration += time.Since(start)
 }

vendor/github.com/felixge/httpsnoop/wrap_generated_lt_1.8.go

@@ -68,115 +68,131 @@ func Wrap(w http.ResponseWriter, hooks Hooks) http.ResponseWriter {
 	// combination 1/16
 	case !i0 && !i1 && !i2 && !i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
-		}{rw}
+		}{rw, rw}
 	// combination 2/16
 	case !i0 && !i1 && !i2 && i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			io.ReaderFrom
-		}{rw, rw}
+		}{rw, rw, rw}
 	// combination 3/16
 	case !i0 && !i1 && i2 && !i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			http.Hijacker
-		}{rw, rw}
+		}{rw, rw, rw}
 	// combination 4/16
 	case !i0 && !i1 && i2 && i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			http.Hijacker
 			io.ReaderFrom
-		}{rw, rw, rw}
+		}{rw, rw, rw, rw}
 	// combination 5/16
 	case !i0 && i1 && !i2 && !i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			http.CloseNotifier
-		}{rw, rw}
+		}{rw, rw, rw}
 	// combination 6/16
 	case !i0 && i1 && !i2 && i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			http.CloseNotifier
 			io.ReaderFrom
-		}{rw, rw, rw}
+		}{rw, rw, rw, rw}
 	// combination 7/16
 	case !i0 && i1 && i2 && !i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			http.CloseNotifier
 			http.Hijacker
-		}{rw, rw, rw}
+		}{rw, rw, rw, rw}
 	// combination 8/16
 	case !i0 && i1 && i2 && i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			http.CloseNotifier
 			http.Hijacker
 			io.ReaderFrom
-		}{rw, rw, rw, rw}
+		}{rw, rw, rw, rw, rw}
 	// combination 9/16
 	case i0 && !i1 && !i2 && !i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			http.Flusher
-		}{rw, rw}
+		}{rw, rw, rw}
 	// combination 10/16
 	case i0 && !i1 && !i2 && i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			http.Flusher
 			io.ReaderFrom
-		}{rw, rw, rw}
+		}{rw, rw, rw, rw}
 	// combination 11/16
 	case i0 && !i1 && i2 && !i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			http.Flusher
 			http.Hijacker
-		}{rw, rw, rw}
+		}{rw, rw, rw, rw}
 	// combination 12/16
 	case i0 && !i1 && i2 && i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			http.Flusher
 			http.Hijacker
 			io.ReaderFrom
-		}{rw, rw, rw, rw}
+		}{rw, rw, rw, rw, rw}
 	// combination 13/16
 	case i0 && i1 && !i2 && !i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			http.Flusher
 			http.CloseNotifier
-		}{rw, rw, rw}
+		}{rw, rw, rw, rw}
 	// combination 14/16
 	case i0 && i1 && !i2 && i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			http.Flusher
 			http.CloseNotifier
 			io.ReaderFrom
-		}{rw, rw, rw, rw}
+		}{rw, rw, rw, rw, rw}
 	// combination 15/16
 	case i0 && i1 && i2 && !i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			http.Flusher
 			http.CloseNotifier
 			http.Hijacker
-		}{rw, rw, rw, rw}
+		}{rw, rw, rw, rw, rw}
 	// combination 16/16
 	case i0 && i1 && i2 && i3:
 		return struct {
+			Unwrapper
 			http.ResponseWriter
 			http.Flusher
 			http.CloseNotifier
 			http.Hijacker
 			io.ReaderFrom
-		}{rw, rw, rw, rw, rw}
+		}{rw, rw, rw, rw, rw, rw}
 	}
 	panic("unreachable")
 }
@@ -186,6 +202,10 @@ type rw struct {
 	h Hooks
 }
 
+func (w *rw) Unwrap() http.ResponseWriter {
+	return w.w
+}
+
 func (w *rw) Header() http.Header {
 	f := w.w.(http.ResponseWriter).Header
 	if w.h.Header != nil {
@@ -241,3 +261,18 @@ func (w *rw) ReadFrom(src io.Reader) (int64, error) {
 	}
 	return f(src)
 }
+
+type Unwrapper interface {
+	Unwrap() http.ResponseWriter
+}
+
+// Unwrap returns the underlying http.ResponseWriter from within zero or more
+// layers of httpsnoop wrappers.
+func Unwrap(w http.ResponseWriter) http.ResponseWriter {
+	if rw, ok := w.(Unwrapper); ok {
+		// recurse until rw.Unwrap() returns a non-Unwrapper
+		return Unwrap(rw.Unwrap())
+	} else {
+		return w
+	}
+}