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Optional memcached between probes and S3

Browse Source 
If given settings for memcached, services will store & fetch reports
from memcache after checking their in-process cache but before fetching
from S3.
This commit is contained in:
Jonathan Lange
2016-06-14 10:42:20 +01:00
parent 37f482cee4
commit 47fcb52354
9 changed files with 1319 additions and 55 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
app/multitenant/common.go
View File

@@ -13,10 +13,28 @@ func errorCode(err error) string {
return "500"
}
// timeRequest runs 'f' and records how long it took in the given Prometheus
// metric. If 'f' returns successfully, record a "200". Otherwise, record
// "500".
//
// If you want more complicated logic for translating errors into statuses,
// use 'timeRequestStatus'.
func timeRequest(method string, metric *prometheus.SummaryVec, f func() error) error {
return timeRequestStatus(method, metric, errorCode, f)
}
// timeRequestStatus runs 'f' and records how long it took in the given
// Prometheus metric.
//
// toStatusCode is a function that translates errors returned by 'f' into
// HTTP-like status codes.
func timeRequestStatus(method string, metric *prometheus.SummaryVec, toStatusCode func(error) string, f func() error) error {
if toStatusCode == nil {
toStatusCode = errorCode
}
startTime := time.Now()
err := f()
duration := time.Now().Sub(startTime)
metric.WithLabelValues(method, errorCode(err)).Observe(float64(duration.Nanoseconds()))
metric.WithLabelValues(method, toStatusCode(err)).Observe(float64(duration.Nanoseconds()))
return err
}

166
app/multitenant/dynamo_collector.go
View File

@@ -15,6 +15,7 @@ import (
"github.com/aws/aws-sdk-go/service/dynamodb"
"github.com/aws/aws-sdk-go/service/s3"
"github.com/bluele/gcache"
"github.com/bradfitz/gomemcache/memcache"
"github.com/nats-io/nats"
"github.com/prometheus/client_golang/prometheus"
"golang.org/x/net/context"
@@ -24,12 +25,16 @@ import (
)
const (
hourField = "hour"
tsField = "ts"
reportField = "report"
reportCacheSize = (15 / 3) * 10 * 5 // (window size * report rate) * number of hosts per user * number of users
reportCacheExpiration = 15 * time.Second
natsTimeout = 10 * time.Second
hourField = "hour"
tsField = "ts"
reportField = "report"
reportCacheSize = (15 / 3) * 10 * 5 // (window size * report rate) * number of hosts per user * number of users
reportCacheExpiration = 15 * time.Second
memcacheExpiration = 15 // seconds
memcacheUpdateInterval = 1 * time.Minute
natsTimeout = 10 * time.Second
hitLabel = "hit"
missLabel = "miss"
)
var (
@@ -38,16 +43,6 @@ var (
Name: "dynamo_request_duration_nanoseconds",
Help: "Time spent doing DynamoDB requests.",
}, []string{"method", "status_code"})
dynamoCacheHits = prometheus.NewCounter(prometheus.CounterOpts{
Namespace: "scope",
Name: "dynamo_cache_hits",
Help: "Reports fetches that hit local cache.",
})
dynamoCacheMiss = prometheus.NewCounter(prometheus.CounterOpts{
Namespace: "scope",
Name: "dynamo_cache_miss",
Help: "Reports fetches that miss local cache.",
})
dynamoConsumedCapacity = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: "scope",
Name: "dynamo_consumed_capacity",
@@ -59,6 +54,12 @@ var (
Help: "Size of data read / written from dynamodb.",
}, []string{"method"})
inProcessCacheCounter = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: "scope",
Name: "in_process_cache",
Help: "Reports fetches that hit in-process cache.",
}, []string{"result"})
reportSize = prometheus.NewCounter(prometheus.CounterOpts{
Namespace: "scope",
Name: "report_size_bytes",
@@ -80,10 +81,9 @@ var (
func init() {
prometheus.MustRegister(dynamoRequestDuration)
prometheus.MustRegister(dynamoCacheHits)
prometheus.MustRegister(dynamoCacheMiss)
prometheus.MustRegister(dynamoConsumedCapacity)
prometheus.MustRegister(dynamoValueSize)
prometheus.MustRegister(inProcessCacheCounter)
prometheus.MustRegister(reportSize)
prometheus.MustRegister(s3RequestDuration)
prometheus.MustRegister(natsRequests)
@@ -95,6 +95,11 @@ type DynamoDBCollector interface {
CreateTables() error
}
// ReportStore is a thing that we can get reports from.
type ReportStore interface {
FetchReports([]string) ([]report.Report, []string, error)
}
type dynamoDBCollector struct {
userIDer UserIDer
db *dynamodb.DynamoDB
@@ -102,7 +107,8 @@ type dynamoDBCollector struct {
tableName string
bucketName string
merger app.Merger
cache gcache.Cache
inProcess inProcessStore
memcache *MemcacheClient
nats *nats.Conn
waitersLock sync.Mutex
@@ -128,7 +134,8 @@ type watchKey struct {
func NewDynamoDBCollector(
userIDer UserIDer,
dynamoDBConfig, s3Config *aws.Config,
tableName, bucketName, natsHost string,
tableName, bucketName, natsHost, memcachedHost string,
memcachedTimeout time.Duration, memcachedService string,
) (DynamoDBCollector, error) {
var nc *nats.Conn
if natsHost != "" {
@@ -139,6 +146,22 @@ func NewDynamoDBCollector(
}
}
var memcacheClient *MemcacheClient
if memcachedHost != "" {
var err error
memcacheClient, err = NewMemcacheClient(memcachedHost, memcachedTimeout, memcachedService, memcacheUpdateInterval, memcacheExpiration)
if err != nil {
// TODO(jml): Ideally, we wouldn't abort here, we would instead
// log errors when we try to use the memcache & fail to do so, as
// aborting here introduces ordering dependencies into our
// deployment.
//
// Note: this error only happens when either the memcachedHost or
// any of the SRV records that it points to fail to resolve.
return nil, err
}
}
return &dynamoDBCollector{
db: dynamodb.New(session.New(dynamoDBConfig)),
s3: s3.New(session.New(s3Config)),
@@ -146,7 +169,8 @@ func NewDynamoDBCollector(
tableName: tableName,
bucketName: bucketName,
merger: app.NewSmartMerger(),
cache: gcache.New(reportCacheSize).LRU().Expiration(reportCacheExpiration).Build(),
inProcess: newInProcessStore(reportCacheSize, reportCacheExpiration),
memcache: memcacheClient,
nats: nc,
waiters: map[watchKey]*nats.Subscription{},
}, nil
@@ -252,20 +276,6 @@ func (c *dynamoDBCollector) getReportKeys(rowKey string, start, end time.Time) (
return result, nil
}
func (c *dynamoDBCollector) getCached(reportKeys []string) ([]report.Report, []string) {
foundReports := []report.Report{}
missingReports := []string{}
for _, reportKey := range reportKeys {
rpt, err := c.cache.Get(reportKey)
if err == nil {
foundReports = append(foundReports, rpt.(report.Report))
} else {
missingReports = append(missingReports, reportKey)
}
}
return foundReports, missingReports
}
// Fetch multiple reports in parallel from S3.
func (c *dynamoDBCollector) getNonCached(reportKeys []string) ([]report.Report, error) {
type result struct {
@@ -291,7 +301,7 @@ func (c *dynamoDBCollector) getNonCached(reportKeys []string) ([]report.Report,
return nil, r.err
}
reports = append(reports, *r.report)
c.cache.Set(r.key, *r.report)
c.inProcess.StoreReport(r.key, *r.report)
}
return reports, nil
}
@@ -315,24 +325,46 @@ func (c *dynamoDBCollector) getNonCachedReport(reportKey string) (*report.Report
func (c *dynamoDBCollector) getReports(userid string, row int64, start, end time.Time) ([]report.Report, error) {
rowKey := fmt.Sprintf("%s-%s", userid, strconv.FormatInt(row, 10))
reportKeys, err := c.getReportKeys(rowKey, start, end)
missing, err := c.getReportKeys(rowKey, start, end)
if err != nil {
return nil, err
}
cachedReports, missing := c.getCached(reportKeys)
dynamoCacheHits.Add(float64(len(cachedReports)))
dynamoCacheMiss.Add(float64(len(missing)))
if len(missing) == 0 {
return cachedReports, nil
var reports []report.Report
for _, store := range []ReportStore{c.inProcess, c.memcache} {
if store == nil {
continue
}
found, missing, err := store.FetchReports(missing)
if err != nil {
log.Warningf("Error fetching from cache: %v", err)
}
reports = append(reports, found...)
if len(missing) == 0 {
return reports, nil
}
}
fetchedReport, err := c.getNonCached(missing)
fetchedReports, err := c.getNonCached(missing)
if err != nil {
return nil, err
}
return append(cachedReports, fetchedReport...), nil
return append(reports, fetchedReports...), nil
}
func memcacheStatusCode(err error) string {
// See https://godoc.org/github.com/bradfitz/gomemcache/memcache#pkg-variables
switch err {
case nil:
return "200"
case memcache.ErrCacheMiss:
return "404"
case memcache.ErrMalformedKey:
return "400"
default:
return "500"
}
}
func (c *dynamoDBCollector) Report(ctx context.Context) (report.Report, error) {
@@ -402,7 +434,20 @@ func (c *dynamoDBCollector) Add(ctx context.Context, rep report.Report) error {
return err
}
// third, put the key in dynamodb
// third, put it in memcache
if c.memcache != nil {
err = timeRequestStatus("Put", memcacheRequestDuration, memcacheStatusCode, func() error {
return c.memcache.StoreBytes(s3Key, buf.Bytes())
})
if err != nil {
// NOTE: We don't abort here because failing to store in memcache
// doesn't actually break anything else -- it's just an
// optimization.
log.Warningf("Could not store %v in memcache: %v", s3Key, err)
}
}
// fourth, put the key in dynamodb
dynamoValueSize.WithLabelValues("PutItem").
Add(float64(len(s3Key)))
@@ -509,3 +554,34 @@ func (c *dynamoDBCollector) UnWait(ctx context.Context, waiter chan struct{}) {
log.Errorf("Error on unsubscribe: %v", err)
}
}
type inProcessStore struct {
cache gcache.Cache
}
// newInProcessStore creates an in-process store for reports.
func newInProcessStore(size int, expiration time.Duration) inProcessStore {
return inProcessStore{gcache.New(size).LRU().Expiration(expiration).Build()}
}
// FetchReports retrieves the given reports from the store.
func (c inProcessStore) FetchReports(keys []string) ([]report.Report, []string, error) {
found := []report.Report{}
missing := []string{}
for _, key := range keys {
rpt, err := c.cache.Get(key)
if err == nil {
found = append(found, rpt.(report.Report))
} else {
missing = append(missing, key)
}
}
inProcessCacheCounter.WithLabelValues(hitLabel).Add(float64(len(found)))
inProcessCacheCounter.WithLabelValues(missLabel).Add(float64(len(missing)))
return found, missing, nil
}
// StoreReport stores a report in the store.
func (c inProcessStore) StoreReport(key string, report report.Report) {
c.cache.Set(key, report)
}

170
app/multitenant/memcache_client.go Normal file
View File

@@ -0,0 +1,170 @@
package multitenant
import (
"bytes"
"fmt"
"net"
"sort"
"sync"
"time"
log "github.com/Sirupsen/logrus"
"github.com/bradfitz/gomemcache/memcache"
"github.com/prometheus/client_golang/prometheus"
"github.com/weaveworks/scope/report"
)
var (
memcacheCounter = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: "scope",
Name: "memcache",
Help: "Reports that missed our in-memory cache but went to our memcache",
}, []string{"result"})
memcacheRequestDuration = prometheus.NewSummaryVec(prometheus.SummaryOpts{
Namespace: "scope",
Name: "memcache_request_duration_nanoseconds",
Help: "Time spent doing memcache requests.",
}, []string{"method", "status_code"})
)
func init() {
prometheus.MustRegister(memcacheCounter)
prometheus.MustRegister(memcacheRequestDuration)
}
// MemcacheClient is a memcache client that gets its server list from SRV
// records, and periodically updates that ServerList.
type MemcacheClient struct {
client *memcache.Client
serverList *memcache.ServerList
expiration int32
hostname string
service string
quit chan struct{}
wait sync.WaitGroup
}
// NewMemcacheClient creates a new MemcacheClient that gets its server list
// from SRV and updates the server list on a regular basis.
func NewMemcacheClient(host string, timeout time.Duration, service string, updateInterval time.Duration, expiration int32) (*MemcacheClient, error) {
var servers memcache.ServerList
client := memcache.NewFromSelector(&servers)
client.Timeout = timeout
newClient := &MemcacheClient{
client: client,
serverList: &servers,
expiration: expiration,
hostname: host,
service: service,
quit: make(chan struct{}),
}
err := newClient.updateMemcacheServers()
if err != nil {
return nil, err
}
newClient.wait.Add(1)
go newClient.updateLoop(updateInterval)
return newClient, nil
}
// Stop the memcache client.
func (c *MemcacheClient) Stop() {
close(c.quit)
c.wait.Wait()
}
func (c *MemcacheClient) updateLoop(updateInterval time.Duration) error {
defer c.wait.Done()
ticker := time.NewTicker(updateInterval)
var err error
for {
select {
case <-ticker.C:
err = c.updateMemcacheServers()
if err != nil {
log.Warningf("Error updating memcache servers: %v", err)
}
case <-c.quit:
ticker.Stop()
}
}
}
// updateMemcacheServers sets a memcache server list from SRV records. SRV
// priority & weight are ignored.
func (c *MemcacheClient) updateMemcacheServers() error {
_, addrs, err := net.LookupSRV(c.service, "tcp", c.hostname)
if err != nil {
return err
}
var servers []string
for _, srv := range addrs {
servers = append(servers, fmt.Sprintf("%s:%d", srv.Target, srv.Port))
}
// ServerList deterministically maps keys to _index_ of the server list.
// Since DNS returns records in different order each time, we sort to
// guarantee best possible match between nodes.
sort.Strings(servers)
return c.serverList.SetServers(servers...)
}
// FetchReports gets reports from memcache.
func (c *MemcacheClient) FetchReports(keys []string) ([]report.Report, []string, error) {
var found map[string]*memcache.Item
err := timeRequestStatus("Get", memcacheRequestDuration, memcacheStatusCode, func() error {
var err error
found, err = c.client.GetMulti(keys)
return err
})
if err != nil {
return nil, keys, err
}
// Decode all the reports in parallel.
type result struct {
key string
report *report.Report
}
ch := make(chan result, len(keys))
var missing []string
for _, key := range keys {
item, ok := found[key]
if !ok {
missing = append(missing, key)
continue
}
go func(key string) {
rep, err := report.MakeFromBinary(bytes.NewReader(item.Value))
if err != nil {
log.Warningf("Corrupt report in memcache %v: %v", key, err)
ch <- result{key: key}
return
}
ch <- result{report: rep}
}(key)
}
var reports []report.Report
for i := 0; i < len(keys)-len(missing); i++ {
r := <-ch
if r.report == nil {
missing = append(missing, r.key)
} else {
reports = append(reports, *r.report)
}
}
memcacheCounter.WithLabelValues(hitLabel).Add(float64(len(reports)))
memcacheCounter.WithLabelValues(missLabel).Add(float64(len(missing)))
return reports, missing, nil
}
// StoreBytes stores a report, expecting the report to be serialized already.
func (c *MemcacheClient) StoreBytes(key string, content []byte) error {
item := memcache.Item{Key: key, Value: content, Expiration: c.expiration}
return c.client.Set(&item)
}

9
prog/app.go
View File

@@ -76,7 +76,7 @@ func awsConfigFromURL(url *url.URL) (*aws.Config, error) {
return config, nil
}
func collectorFactory(userIDer multitenant.UserIDer, collectorURL, s3URL, natsHostname string, window time.Duration, createTables bool) (app.Collector, error) {
func collectorFactory(userIDer multitenant.UserIDer, collectorURL, s3URL, natsHostname, memcachedHostname string, memcachedTimeout time.Duration, memcachedService string, window time.Duration, createTables bool) (app.Collector, error) {
if collectorURL == "local" {
return app.NewCollector(window), nil
}
@@ -102,7 +102,9 @@ func collectorFactory(userIDer multitenant.UserIDer, collectorURL, s3URL, natsHo
tableName := strings.TrimPrefix(parsed.Path, "/")
bucketName := strings.TrimPrefix(s3.Path, "/")
dynamoCollector, err := multitenant.NewDynamoDBCollector(
userIDer, dynamoDBConfig, s3Config, tableName, bucketName, natsHostname)
userIDer, dynamoDBConfig, s3Config, tableName, bucketName, natsHostname,
memcachedHostname, memcachedTimeout, memcachedService,
)
if err != nil {
return nil, err
}
@@ -183,7 +185,8 @@ func appMain(flags appFlags) {
}
collector, err := collectorFactory(
userIDer, flags.collectorURL, flags.s3URL, flags.natsHostname, flags.window, flags.awsCreateTables)
userIDer, flags.collectorURL, flags.s3URL, flags.natsHostname, flags.memcachedHostname,
flags.memcachedTimeout, flags.memcachedService, flags.window, flags.awsCreateTables)
if err != nil {
log.Fatalf("Error creating collector: %v", err)
return

18
prog/main.go
View File

@@ -96,12 +96,15 @@ type appFlags struct {
containerName string
dockerEndpoint string
collectorURL string
s3URL string
controlRouterURL string
pipeRouterURL string
natsHostname string
userIDHeader string
collectorURL string
s3URL string
controlRouterURL string
pipeRouterURL string
natsHostname string
memcachedHostname string
memcachedTimeout time.Duration
memcachedService string
userIDHeader string
awsCreateTables bool
consulInf string
@@ -178,6 +181,9 @@ func main() {
flag.StringVar(&flags.app.controlRouterURL, "app.control.router", "local", "Control router to use (local or sqs)")
flag.StringVar(&flags.app.pipeRouterURL, "app.pipe.router", "local", "Pipe router to use (local)")
flag.StringVar(&flags.app.natsHostname, "app.nats", "", "Hostname for NATS service to use for shortcut reports. If empty, shortcut reporting will be disabled.")
flag.StringVar(&flags.app.memcachedHostname, "app.memcached.hostname", "", "Hostname for memcached service to use when caching reports. If empty, no memcached will be used.")
flag.DurationVar(&flags.app.memcachedTimeout, "app.memcached.timeout", 100*time.Millisecond, "Maximum time to wait before giving up on memcached requests.")
flag.StringVar(&flags.app.memcachedService, "app.memcached.service", "memcached", "SRV service used to discover memcache servers.")
flag.StringVar(&flags.app.userIDHeader, "app.userid.header", "", "HTTP header to use as userid")
flag.BoolVar(&flags.app.awsCreateTables, "app.aws.create.tables", false, "Create the tables in DynamoDB")

202
vendor/github.com/bradfitz/gomemcache/memcache/LICENSE generated vendored Normal file
View File

@@ -0,0 +1,202 @@
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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.
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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
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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 [yyyy] [name of copyright owner]
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
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Unless required by applicable law or agreed to in writing, software
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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666
vendor/github.com/bradfitz/gomemcache/memcache/memcache.go generated vendored Normal file
View File

@@ -0,0 +1,666 @@
/*
Copyright 2011 Google Inc.
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.
*/
// Package memcache provides a client for the memcached cache server.
package memcache
import (
"bufio"
"bytes"
"errors"
"fmt"
"io"
"io/ioutil"
"net"
"strconv"
"strings"
"sync"
"time"
)
// Similar to:
// http://code.google.com/appengine/docs/go/memcache/reference.html
var (
// ErrCacheMiss means that a Get failed because the item wasn't present.
ErrCacheMiss = errors.New("memcache: cache miss")
// ErrCASConflict means that a CompareAndSwap call failed due to the
// cached value being modified between the Get and the CompareAndSwap.
// If the cached value was simply evicted rather than replaced,
// ErrNotStored will be returned instead.
ErrCASConflict = errors.New("memcache: compare-and-swap conflict")
// ErrNotStored means that a conditional write operation (i.e. Add or
// CompareAndSwap) failed because the condition was not satisfied.
ErrNotStored = errors.New("memcache: item not stored")
// ErrServer means that a server error occurred.
ErrServerError = errors.New("memcache: server error")
// ErrNoStats means that no statistics were available.
ErrNoStats = errors.New("memcache: no statistics available")
// ErrMalformedKey is returned when an invalid key is used.
// Keys must be at maximum 250 bytes long, ASCII, and not
// contain whitespace or control characters.
ErrMalformedKey = errors.New("malformed: key is too long or contains invalid characters")
// ErrNoServers is returned when no servers are configured or available.
ErrNoServers = errors.New("memcache: no servers configured or available")
)
// DefaultTimeout is the default socket read/write timeout.
const DefaultTimeout = 100 * time.Millisecond
const (
buffered = 8 // arbitrary buffered channel size, for readability
maxIdleConnsPerAddr = 2 // TODO(bradfitz): make this configurable?
)
// resumableError returns true if err is only a protocol-level cache error.
// This is used to determine whether or not a server connection should
// be re-used or not. If an error occurs, by default we don't reuse the
// connection, unless it was just a cache error.
func resumableError(err error) bool {
switch err {
case ErrCacheMiss, ErrCASConflict, ErrNotStored, ErrMalformedKey:
return true
}
return false
}
func legalKey(key string) bool {
if len(key) > 250 {
return false
}
for i := 0; i < len(key); i++ {
if key[i] <= ' ' || key[i] > 0x7e {
return false
}
}
return true
}
var (
crlf = []byte("\r\n")
space = []byte(" ")
resultOK = []byte("OK\r\n")
resultStored = []byte("STORED\r\n")
resultNotStored = []byte("NOT_STORED\r\n")
resultExists = []byte("EXISTS\r\n")
resultNotFound = []byte("NOT_FOUND\r\n")
resultDeleted = []byte("DELETED\r\n")
resultEnd = []byte("END\r\n")
resultOk = []byte("OK\r\n")
resultTouched = []byte("TOUCHED\r\n")
resultClientErrorPrefix = []byte("CLIENT_ERROR ")
)
// New returns a memcache client using the provided server(s)
// with equal weight. If a server is listed multiple times,
// it gets a proportional amount of weight.
func New(server ...string) *Client {
ss := new(ServerList)
ss.SetServers(server...)
return NewFromSelector(ss)
}
// NewFromSelector returns a new Client using the provided ServerSelector.
func NewFromSelector(ss ServerSelector) *Client {
return &Client{selector: ss}
}
// Client is a memcache client.
// It is safe for unlocked use by multiple concurrent goroutines.
type Client struct {
// Timeout specifies the socket read/write timeout.
// If zero, DefaultTimeout is used.
Timeout time.Duration
selector ServerSelector
lk sync.Mutex
freeconn map[string][]*conn
}
// Item is an item to be got or stored in a memcached server.
type Item struct {
// Key is the Item's key (250 bytes maximum).
Key string
// Value is the Item's value.
Value []byte
// Flags are server-opaque flags whose semantics are entirely
// up to the app.
Flags uint32
// Expiration is the cache expiration time, in seconds: either a relative
// time from now (up to 1 month), or an absolute Unix epoch time.
// Zero means the Item has no expiration time.
Expiration int32
// Compare and swap ID.
casid uint64
}
// conn is a connection to a server.
type conn struct {
nc net.Conn
rw *bufio.ReadWriter
addr net.Addr
c *Client
}
// release returns this connection back to the client's free pool
func (cn *conn) release() {
cn.c.putFreeConn(cn.addr, cn)
}
func (cn *conn) extendDeadline() {
cn.nc.SetDeadline(time.Now().Add(cn.c.netTimeout()))
}
// condRelease releases this connection if the error pointed to by err
// is nil (not an error) or is only a protocol level error (e.g. a
// cache miss). The purpose is to not recycle TCP connections that
// are bad.
func (cn *conn) condRelease(err *error) {
if *err == nil || resumableError(*err) {
cn.release()
} else {
cn.nc.Close()
}
}
func (c *Client) putFreeConn(addr net.Addr, cn *conn) {
c.lk.Lock()
defer c.lk.Unlock()
if c.freeconn == nil {
c.freeconn = make(map[string][]*conn)
}
freelist := c.freeconn[addr.String()]
if len(freelist) >= maxIdleConnsPerAddr {
cn.nc.Close()
return
}
c.freeconn[addr.String()] = append(freelist, cn)
}
func (c *Client) getFreeConn(addr net.Addr) (cn *conn, ok bool) {
c.lk.Lock()
defer c.lk.Unlock()
if c.freeconn == nil {
return nil, false
}
freelist, ok := c.freeconn[addr.String()]
if !ok || len(freelist) == 0 {
return nil, false
}
cn = freelist[len(freelist)-1]
c.freeconn[addr.String()] = freelist[:len(freelist)-1]
return cn, true
}
func (c *Client) netTimeout() time.Duration {
if c.Timeout != 0 {
return c.Timeout
}
return DefaultTimeout
}
// ConnectTimeoutError is the error type used when it takes
// too long to connect to the desired host. This level of
// detail can generally be ignored.
type ConnectTimeoutError struct {
Addr net.Addr
}
func (cte *ConnectTimeoutError) Error() string {
return "memcache: connect timeout to " + cte.Addr.String()
}
func (c *Client) dial(addr net.Addr) (net.Conn, error) {
type connError struct {
cn net.Conn
err error
}
nc, err := net.DialTimeout(addr.Network(), addr.String(), c.netTimeout())
if err == nil {
return nc, nil
}
if ne, ok := err.(net.Error); ok && ne.Timeout() {
return nil, &ConnectTimeoutError{addr}
}
return nil, err
}
func (c *Client) getConn(addr net.Addr) (*conn, error) {
cn, ok := c.getFreeConn(addr)
if ok {
cn.extendDeadline()
return cn, nil
}
nc, err := c.dial(addr)
if err != nil {
return nil, err
}
cn = &conn{
nc: nc,
addr: addr,
rw: bufio.NewReadWriter(bufio.NewReader(nc), bufio.NewWriter(nc)),
c: c,
}
cn.extendDeadline()
return cn, nil
}
func (c *Client) onItem(item *Item, fn func(*Client, *bufio.ReadWriter, *Item) error) error {
addr, err := c.selector.PickServer(item.Key)
if err != nil {
return err
}
cn, err := c.getConn(addr)
if err != nil {
return err
}
defer cn.condRelease(&err)
if err = fn(c, cn.rw, item); err != nil {
return err
}
return nil
}
func (c *Client) FlushAll() error {
return c.selector.Each(c.flushAllFromAddr)
}
// Get gets the item for the given key. ErrCacheMiss is returned for a
// memcache cache miss. The key must be at most 250 bytes in length.
func (c *Client) Get(key string) (item *Item, err error) {
err = c.withKeyAddr(key, func(addr net.Addr) error {
return c.getFromAddr(addr, []string{key}, func(it *Item) { item = it })
})
if err == nil && item == nil {
err = ErrCacheMiss
}
return
}
// Touch updates the expiry for the given key. The seconds parameter is either
// a Unix timestamp or, if seconds is less than 1 month, the number of seconds
// into the future at which time the item will expire. ErrCacheMiss is returned if the
// key is not in the cache. The key must be at most 250 bytes in length.
func (c *Client) Touch(key string, seconds int32) (err error) {
return c.withKeyAddr(key, func(addr net.Addr) error {
return c.touchFromAddr(addr, []string{key}, seconds)
})
}
func (c *Client) withKeyAddr(key string, fn func(net.Addr) error) (err error) {
if !legalKey(key) {
return ErrMalformedKey
}
addr, err := c.selector.PickServer(key)
if err != nil {
return err
}
return fn(addr)
}
func (c *Client) withAddrRw(addr net.Addr, fn func(*bufio.ReadWriter) error) (err error) {
cn, err := c.getConn(addr)
if err != nil {
return err
}
defer cn.condRelease(&err)
return fn(cn.rw)
}
func (c *Client) withKeyRw(key string, fn func(*bufio.ReadWriter) error) error {
return c.withKeyAddr(key, func(addr net.Addr) error {
return c.withAddrRw(addr, fn)
})
}
func (c *Client) getFromAddr(addr net.Addr, keys []string, cb func(*Item)) error {
return c.withAddrRw(addr, func(rw *bufio.ReadWriter) error {
if _, err := fmt.Fprintf(rw, "gets %s\r\n", strings.Join(keys, " ")); err != nil {
return err
}
if err := rw.Flush(); err != nil {
return err
}
if err := parseGetResponse(rw.Reader, cb); err != nil {
return err
}
return nil
})
}
// flushAllFromAddr send the flush_all command to the given addr
func (c *Client) flushAllFromAddr(addr net.Addr) error {
return c.withAddrRw(addr, func(rw *bufio.ReadWriter) error {
if _, err := fmt.Fprintf(rw, "flush_all\r\n"); err != nil {
return err
}
if err := rw.Flush(); err != nil {
return err
}
line, err := rw.ReadSlice('\n')
if err != nil {
return err
}
switch {
case bytes.Equal(line, resultOk):
break
default:
return fmt.Errorf("memcache: unexpected response line from flush_all: %q", string(line))
}
return nil
})
}
func (c *Client) touchFromAddr(addr net.Addr, keys []string, expiration int32) error {
return c.withAddrRw(addr, func(rw *bufio.ReadWriter) error {
for _, key := range keys {
if _, err := fmt.Fprintf(rw, "touch %s %d\r\n", key, expiration); err != nil {
return err
}
if err := rw.Flush(); err != nil {
return err
}
line, err := rw.ReadSlice('\n')
if err != nil {
return err
}
switch {
case bytes.Equal(line, resultTouched):
break
case bytes.Equal(line, resultNotFound):
return ErrCacheMiss
default:
return fmt.Errorf("memcache: unexpected response line from touch: %q", string(line))
}
}
return nil
})
}
// GetMulti is a batch version of Get. The returned map from keys to
// items may have fewer elements than the input slice, due to memcache
// cache misses. Each key must be at most 250 bytes in length.
// If no error is returned, the returned map will also be non-nil.
func (c *Client) GetMulti(keys []string) (map[string]*Item, error) {
var lk sync.Mutex
m := make(map[string]*Item)
addItemToMap := func(it *Item) {
lk.Lock()
defer lk.Unlock()
m[it.Key] = it
}
keyMap := make(map[net.Addr][]string)
for _, key := range keys {
if !legalKey(key) {
return nil, ErrMalformedKey
}
addr, err := c.selector.PickServer(key)
if err != nil {
return nil, err
}
keyMap[addr] = append(keyMap[addr], key)
}
ch := make(chan error, buffered)
for addr, keys := range keyMap {
go func(addr net.Addr, keys []string) {
ch <- c.getFromAddr(addr, keys, addItemToMap)
}(addr, keys)
}
var err error
for _ = range keyMap {
if ge := <-ch; ge != nil {
err = ge
}
}
return m, err
}
// parseGetResponse reads a GET response from r and calls cb for each
// read and allocated Item
func parseGetResponse(r *bufio.Reader, cb func(*Item)) error {
for {
line, err := r.ReadSlice('\n')
if err != nil {
return err
}
if bytes.Equal(line, resultEnd) {
return nil
}
it := new(Item)
size, err := scanGetResponseLine(line, it)
if err != nil {
return err
}
it.Value, err = ioutil.ReadAll(io.LimitReader(r, int64(size)+2))
if err != nil {
return err
}
if !bytes.HasSuffix(it.Value, crlf) {
return fmt.Errorf("memcache: corrupt get result read")
}
it.Value = it.Value[:size]
cb(it)
}
}
// scanGetResponseLine populates it and returns the declared size of the item.
// It does not read the bytes of the item.
func scanGetResponseLine(line []byte, it *Item) (size int, err error) {
pattern := "VALUE %s %d %d %d\r\n"
dest := []interface{}{&it.Key, &it.Flags, &size, &it.casid}
if bytes.Count(line, space) == 3 {
pattern = "VALUE %s %d %d\r\n"
dest = dest[:3]
}
n, err := fmt.Sscanf(string(line), pattern, dest...)
if err != nil || n != len(dest) {
return -1, fmt.Errorf("memcache: unexpected line in get response: %q", line)
}
return size, nil
}
// Set writes the given item, unconditionally.
func (c *Client) Set(item *Item) error {
return c.onItem(item, (*Client).set)
}
func (c *Client) set(rw *bufio.ReadWriter, item *Item) error {
return c.populateOne(rw, "set", item)
}
// Add writes the given item, if no value already exists for its
// key. ErrNotStored is returned if that condition is not met.
func (c *Client) Add(item *Item) error {
return c.onItem(item, (*Client).add)
}
func (c *Client) add(rw *bufio.ReadWriter, item *Item) error {
return c.populateOne(rw, "add", item)
}
// Replace writes the given item, but only if the server *does*
// already hold data for this key
func (c *Client) Replace(item *Item) error {
return c.onItem(item, (*Client).replace)
}
func (c *Client) replace(rw *bufio.ReadWriter, item *Item) error {
return c.populateOne(rw, "replace", item)
}
// CompareAndSwap writes the given item that was previously returned
// by Get, if the value was neither modified or evicted between the
// Get and the CompareAndSwap calls. The item's Key should not change
// between calls but all other item fields may differ. ErrCASConflict
// is returned if the value was modified in between the
// calls. ErrNotStored is returned if the value was evicted in between
// the calls.
func (c *Client) CompareAndSwap(item *Item) error {
return c.onItem(item, (*Client).cas)
}
func (c *Client) cas(rw *bufio.ReadWriter, item *Item) error {
return c.populateOne(rw, "cas", item)
}
func (c *Client) populateOne(rw *bufio.ReadWriter, verb string, item *Item) error {
if !legalKey(item.Key) {
return ErrMalformedKey
}
var err error
if verb == "cas" {
_, err = fmt.Fprintf(rw, "%s %s %d %d %d %d\r\n",
verb, item.Key, item.Flags, item.Expiration, len(item.Value), item.casid)
} else {
_, err = fmt.Fprintf(rw, "%s %s %d %d %d\r\n",
verb, item.Key, item.Flags, item.Expiration, len(item.Value))
}
if err != nil {
return err
}
if _, err = rw.Write(item.Value); err != nil {
return err
}
if _, err := rw.Write(crlf); err != nil {
return err
}
if err := rw.Flush(); err != nil {
return err
}
line, err := rw.ReadSlice('\n')
if err != nil {
return err
}
switch {
case bytes.Equal(line, resultStored):
return nil
case bytes.Equal(line, resultNotStored):
return ErrNotStored
case bytes.Equal(line, resultExists):
return ErrCASConflict
case bytes.Equal(line, resultNotFound):
return ErrCacheMiss
}
return fmt.Errorf("memcache: unexpected response line from %q: %q", verb, string(line))
}
func writeReadLine(rw *bufio.ReadWriter, format string, args ...interface{}) ([]byte, error) {
_, err := fmt.Fprintf(rw, format, args...)
if err != nil {
return nil, err
}
if err := rw.Flush(); err != nil {
return nil, err
}
line, err := rw.ReadSlice('\n')
return line, err
}
func writeExpectf(rw *bufio.ReadWriter, expect []byte, format string, args ...interface{}) error {
line, err := writeReadLine(rw, format, args...)
if err != nil {
return err
}
switch {
case bytes.Equal(line, resultOK):
return nil
case bytes.Equal(line, expect):
return nil
case bytes.Equal(line, resultNotStored):
return ErrNotStored
case bytes.Equal(line, resultExists):
return ErrCASConflict
case bytes.Equal(line, resultNotFound):
return ErrCacheMiss
}
return fmt.Errorf("memcache: unexpected response line: %q", string(line))
}
// Delete deletes the item with the provided key. The error ErrCacheMiss is
// returned if the item didn't already exist in the cache.
func (c *Client) Delete(key string) error {
return c.withKeyRw(key, func(rw *bufio.ReadWriter) error {
return writeExpectf(rw, resultDeleted, "delete %s\r\n", key)
})
}
// DeleteAll deletes all items in the cache.
func (c *Client) DeleteAll() error {
return c.withKeyRw("", func(rw *bufio.ReadWriter) error {
return writeExpectf(rw, resultDeleted, "flush_all\r\n")
})
}
// Increment atomically increments key by delta. The return value is
// the new value after being incremented or an error. If the value
// didn't exist in memcached the error is ErrCacheMiss. The value in
// memcached must be an decimal number, or an error will be returned.
// On 64-bit overflow, the new value wraps around.
func (c *Client) Increment(key string, delta uint64) (newValue uint64, err error) {
return c.incrDecr("incr", key, delta)
}
// Decrement atomically decrements key by delta. The return value is
// the new value after being decremented or an error. If the value
// didn't exist in memcached the error is ErrCacheMiss. The value in
// memcached must be an decimal number, or an error will be returned.
// On underflow, the new value is capped at zero and does not wrap
// around.
func (c *Client) Decrement(key string, delta uint64) (newValue uint64, err error) {
return c.incrDecr("decr", key, delta)
}
func (c *Client) incrDecr(verb, key string, delta uint64) (uint64, error) {
var val uint64
err := c.withKeyRw(key, func(rw *bufio.ReadWriter) error {
line, err := writeReadLine(rw, "%s %s %d\r\n", verb, key, delta)
if err != nil {
return err
}
switch {
case bytes.Equal(line, resultNotFound):
return ErrCacheMiss
case bytes.HasPrefix(line, resultClientErrorPrefix):
errMsg := line[len(resultClientErrorPrefix) : len(line)-2]
return errors.New("memcache: client error: " + string(errMsg))
}
val, err = strconv.ParseUint(string(line[:len(line)-2]), 10, 64)
if err != nil {
return err
}
return nil
})
return val, err
}

114
vendor/github.com/bradfitz/gomemcache/memcache/selector.go generated vendored Normal file
View File

@@ -0,0 +1,114 @@
/*
Copyright 2011 Google Inc.
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.
*/
package memcache
import (
"hash/crc32"
"net"
"strings"
"sync"
)
// ServerSelector is the interface that selects a memcache server
// as a function of the item's key.
//
// All ServerSelector implementations must be safe for concurrent use
// by multiple goroutines.
type ServerSelector interface {
// PickServer returns the server address that a given item
// should be shared onto.
PickServer(key string) (net.Addr, error)
Each(func(net.Addr) error) error
}
// ServerList is a simple ServerSelector. Its zero value is usable.
type ServerList struct {
mu sync.RWMutex
addrs []net.Addr
}
// SetServers changes a ServerList's set of servers at runtime and is
// safe for concurrent use by multiple goroutines.
//
// Each server is given equal weight. A server is given more weight
// if it's listed multiple times.
//
// SetServers returns an error if any of the server names fail to
// resolve. No attempt is made to connect to the server. If any error
// is returned, no changes are made to the ServerList.
func (ss *ServerList) SetServers(servers ...string) error {
naddr := make([]net.Addr, len(servers))
for i, server := range servers {
if strings.Contains(server, "/") {
addr, err := net.ResolveUnixAddr("unix", server)
if err != nil {
return err
}
naddr[i] = addr
} else {
tcpaddr, err := net.ResolveTCPAddr("tcp", server)
if err != nil {
return err
}
naddr[i] = tcpaddr
}
}
ss.mu.Lock()
defer ss.mu.Unlock()
ss.addrs = naddr
return nil
}
// Each iterates over each server calling the given function
func (ss *ServerList) Each(f func(net.Addr) error) error {
ss.mu.RLock()
defer ss.mu.RUnlock()
for _, a := range ss.addrs {
if err := f(a); nil != err {
return err
}
}
return nil
}
// keyBufPool returns []byte buffers for use by PickServer's call to
// crc32.ChecksumIEEE to avoid allocations. (but doesn't avoid the
// copies, which at least are bounded in size and small)
var keyBufPool = sync.Pool{
New: func() interface{} {
b := make([]byte, 256)
return &b
},
}
func (ss *ServerList) PickServer(key string) (net.Addr, error) {
ss.mu.RLock()
defer ss.mu.RUnlock()
if len(ss.addrs) == 0 {
return nil, ErrNoServers
}
if len(ss.addrs) == 1 {
return ss.addrs[0], nil
}
bufp := keyBufPool.Get().(*[]byte)
n := copy(*bufp, key)
cs := crc32.ChecksumIEEE((*bufp)[:n])
keyBufPool.Put(bufp)
return ss.addrs[cs%uint32(len(ss.addrs))], nil
}

9
vendor/manifest vendored
View File

@@ -74,6 +74,15 @@
"revision": "fb6c0b0e1ff03057a054886141927cdce6239dec",
"branch": "master"
},
{
"importpath": "github.com/bradfitz/gomemcache/memcache",
"repository": "https://github.com/bradfitz/gomemcache",
"vcs": "git",
"revision": "fb1f79c6b65acda83063cbc69f6bba1522558bfc",
"branch": "master",
"path": "/memcache",
"notests": true
},
{
"importpath": "github.com/c9s/goprocinfo/linux",
"repository": "https://github.com/c9s/goprocinfo",