vendor: add sourcegraph/s3cache and dependencies

Adds:
 - github.com/kr/http/transport
 - github.com/sqs/s3
 - github.com/sqs/s3/s3util
 - sourcegraph.com/sourcegraph/s3cache

vendor/sourcegraph.com/sourcegraph/s3cache/LICENSE

@@ -0,0 +1,26 @@
+Copyright (c) 2013 The s3cache AUTHORS. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+   * Redistributions of source code must retain the above copyright notice, this
+     list of conditions and the following disclaimer.
+
+   * Redistributions in binary form must reproduce the above copyright notice,
+     this list of conditions and the following disclaimer in the documentation
+     and/or other materials provided with the distribution.
+
+   * Neither the name of Sourcegraph Inc. nor the names of its contributors may
+     be used to endorse or promote products derived from this software without
+     specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/sourcegraph.com/sourcegraph/s3cache/s3cache.go

@@ -0,0 +1,127 @@
+// Package s3cache provides an implementation of httpcache.Cache that stores and
+// retrieves data using Amazon S3.
+package s3cache // import "sourcegraph.com/sourcegraph/s3cache"
+
+import (
+	"compress/gzip"
+	"crypto/md5"
+	"encoding/hex"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+
+	"github.com/sqs/s3"
+	"github.com/sqs/s3/s3util"
+)
+
+// Cache objects store and retrieve data using Amazon S3.
+type Cache struct {
+	// Config is the Amazon S3 configuration.
+	Config s3util.Config
+
+	// BucketURL is the URL to the bucket on Amazon S3, which includes the
+	// bucket name and the AWS region. Example:
+	// "https://s3-us-west-2.amazonaws.com/mybucket".
+	BucketURL string
+
+	// Gzip indicates whether cache entries should be gzipped in Set and
+	// gunzipped in Get. If true, cache entry keys will have the suffix ".gz"
+	// appended.
+	Gzip bool
+}
+
+var noLogErrors, _ = strconv.ParseBool(os.Getenv("NO_LOG_S3CACHE_ERRORS"))
+
+func (c *Cache) Get(key string) (resp []byte, ok bool) {
+	rdr, err := s3util.Open(c.url(key), &c.Config)
+	if err != nil {
+		return []byte{}, false
+	}
+	defer rdr.Close()
+	if c.Gzip {
+		rdr, err = gzip.NewReader(rdr)
+		if err != nil {
+			return nil, false
+		}
+		defer rdr.Close()
+	}
+	resp, err = ioutil.ReadAll(rdr)
+	if err != nil {
+		if !noLogErrors {
+			log.Printf("s3cache.Get failed: %s", err)
+		}
+	}
+	return resp, err == nil
+}
+
+func (c *Cache) Set(key string, resp []byte) {
+	w, err := s3util.Create(c.url(key), nil, &c.Config)
+	if err != nil {
+		if !noLogErrors {
+			log.Printf("s3util.Create failed: %s", err)
+		}
+		return
+	}
+	defer w.Close()
+	if c.Gzip {
+		w = gzip.NewWriter(w)
+		defer w.Close()
+	}
+	_, err = w.Write(resp)
+	if err != nil {
+		if !noLogErrors {
+			log.Printf("s3cache.Set failed: %s", err)
+		}
+	}
+}
+
+func (c *Cache) Delete(key string) {
+	rdr, err := s3util.Delete(c.url(key), &c.Config)
+	if err != nil {
+		if !noLogErrors {
+			log.Printf("s3cache.Delete failed: %s", err)
+		}
+		return
+	}
+	defer rdr.Close()
+}
+
+func (c *Cache) url(key string) string {
+	key = cacheKeyToObjectKey(key)
+	if c.Gzip {
+		key += ".gz"
+	}
+	if strings.HasSuffix(c.BucketURL, "/") {
+		return c.BucketURL + key
+	}
+	return c.BucketURL + "/" + key
+}
+
+func cacheKeyToObjectKey(key string) string {
+	h := md5.New()
+	io.WriteString(h, key)
+	return hex.EncodeToString(h.Sum(nil))
+}
+
+// New returns a new Cache with underlying storage in Amazon S3. The bucketURL
+// is the full URL to the bucket on Amazon S3, including the bucket name and AWS
+// region (e.g., "https://s3-us-west-2.amazonaws.com/mybucket").
+//
+// The environment variables AWS_ACCESS_KEY_ID and AWS_SECRET_KEY are used as the AWS
+// credentials. To use different credentials, modify the returned Cache object
+// or construct a Cache object manually.
+func New(bucketURL string) *Cache {
+	return &Cache{
+		Config: s3util.Config{
+			Keys: &s3.Keys{
+				AccessKey: os.Getenv("AWS_ACCESS_KEY_ID"),
+				SecretKey: os.Getenv("AWS_SECRET_KEY"),
+			},
+			Service: s3.DefaultService,
+		},
+		BucketURL: bucketURL,
+	}
+}