snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

profiling/cmd/catapult.go

@@ -0,0 +1,394 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * 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 main
+
+import (
+	"encoding/binary"
+	"encoding/json"
+	"fmt"
+	"os"
+	"sort"
+	"strings"
+
+	ppb "google.golang.org/grpc/profiling/proto"
+)
+
+type jsonNode struct {
+	Name      string  `json:"name"`
+	Cat       string  `json:"cat"`
+	ID        string  `json:"id"`
+	Cname     string  `json:"cname"`
+	Phase     string  `json:"ph"`
+	Timestamp float64 `json:"ts"`
+	PID       string  `json:"pid"`
+	TID       string  `json:"tid"`
+}
+
+// Catapult does not allow specifying colours manually; a 20-odd predefined
+// labels are used (that don't make much sense outside the context of
+// Chromium). See this for more details:
+//
+// https://github.com/catapult-project/catapult/blob/bef344f7017fc9e04f7049d0f58af6d9ce9f4ab6/tracing/tracing/base/color_scheme.html#L29
+func hashCname(tag string) string {
+	if strings.Contains(tag, "encoding") {
+		return "rail_response"
+	}
+
+	if strings.Contains(tag, "compression") {
+		return "cq_build_passed"
+	}
+
+	if strings.Contains(tag, "transport") {
+		if strings.Contains(tag, "blocking") {
+			return "rail_animation"
+		}
+		return "good"
+	}
+
+	if strings.Contains(tag, "header") {
+		return "cq_build_attempt_failed"
+	}
+
+	if tag == "/" {
+		return "heap_dump_stack_frame"
+	}
+
+	if strings.Contains(tag, "flow") || strings.Contains(tag, "tmp") {
+		return "heap_dump_stack_frame"
+	}
+
+	return ""
+}
+
+// filterCounter identifies the counter-th instance of a timer of the type
+// `filter` within a Stat. This, in conjunction with the counter data structure
+// defined below, is used to draw flows between linked loopy writer/reader
+// events with application goroutine events in trace-viewer. This is possible
+// because enqueues and dequeues are ordered -- that is, the first dequeue must
+// be dequeueing the first enqueue operation.
+func filterCounter(stat *ppb.Stat, filter string, counter int) int {
+	localCounter := 0
+	for i := 0; i < len(stat.Timers); i++ {
+		if stat.Timers[i].Tags == filter {
+			if localCounter == counter {
+				return i
+			}
+			localCounter++
+		}
+	}
+
+	return -1
+}
+
+// counter is state object used to store and retrieve the number of timers of a
+// particular type that have been seen.
+type counter struct {
+	c map[string]int
+}
+
+func newCounter() *counter {
+	return &counter{c: make(map[string]int)}
+}
+
+func (c *counter) GetAndInc(s string) int {
+	ret := c.c[s]
+	c.c[s]++
+	return ret
+}
+
+func catapultNs(sec int64, nsec int32) float64 {
+	return float64((sec * 1000000000) + int64(nsec))
+}
+
+// streamStatsCatapultJSONSingle processes a single proto Stat object to return
+// an array of jsonNodes in trace-viewer's format.
+func streamStatsCatapultJSONSingle(stat *ppb.Stat, baseSec int64, baseNsec int32) []jsonNode {
+	if len(stat.Timers) == 0 {
+		return nil
+	}
+
+	connectionCounter := binary.BigEndian.Uint64(stat.Metadata[0:8])
+	streamID := binary.BigEndian.Uint32(stat.Metadata[8:12])
+	opid := fmt.Sprintf("/%s/%d/%d", stat.Tags, connectionCounter, streamID)
+
+	var loopyReaderGoID, loopyWriterGoID int64
+	for i := 0; i < len(stat.Timers) && (loopyReaderGoID == 0 || loopyWriterGoID == 0); i++ {
+		if strings.Contains(stat.Timers[i].Tags, "/loopyReader") {
+			loopyReaderGoID = stat.Timers[i].GoId
+		} else if strings.Contains(stat.Timers[i].Tags, "/loopyWriter") {
+			loopyWriterGoID = stat.Timers[i].GoId
+		}
+	}
+
+	lrc, lwc := newCounter(), newCounter()
+
+	var result []jsonNode
+	result = append(result,
+		jsonNode{
+			Name:      "loopyReaderTmp",
+			ID:        opid,
+			Cname:     hashCname("tmp"),
+			Phase:     "i",
+			Timestamp: 0,
+			PID:       fmt.Sprintf("/%s/%d/loopyReader", stat.Tags, connectionCounter),
+			TID:       fmt.Sprintf("%d", loopyReaderGoID),
+		},
+		jsonNode{
+			Name:      "loopyWriterTmp",
+			ID:        opid,
+			Cname:     hashCname("tmp"),
+			Phase:     "i",
+			Timestamp: 0,
+			PID:       fmt.Sprintf("/%s/%d/loopyWriter", stat.Tags, connectionCounter),
+			TID:       fmt.Sprintf("%d", loopyWriterGoID),
+		},
+	)
+
+	for i := 0; i < len(stat.Timers); i++ {
+		categories := stat.Tags
+		pid, tid := opid, fmt.Sprintf("%d", stat.Timers[i].GoId)
+
+		if stat.Timers[i].GoId == loopyReaderGoID {
+			pid, tid = fmt.Sprintf("/%s/%d/loopyReader", stat.Tags, connectionCounter), fmt.Sprintf("%d", stat.Timers[i].GoId)
+
+			var flowEndID int
+			var flowEndPID, flowEndTID string
+			switch stat.Timers[i].Tags {
+			case "/http2/recv/header":
+				flowEndID = filterCounter(stat, "/grpc/stream/recv/header", lrc.GetAndInc("/http2/recv/header"))
+				if flowEndID != -1 {
+					flowEndPID = opid
+					flowEndTID = fmt.Sprintf("%d", stat.Timers[flowEndID].GoId)
+				} else {
+					logger.Infof("cannot find %s/grpc/stream/recv/header for %s/http2/recv/header", opid, opid)
+				}
+			case "/http2/recv/dataFrame/loopyReader":
+				flowEndID = filterCounter(stat, "/recvAndDecompress", lrc.GetAndInc("/http2/recv/dataFrame/loopyReader"))
+				if flowEndID != -1 {
+					flowEndPID = opid
+					flowEndTID = fmt.Sprintf("%d", stat.Timers[flowEndID].GoId)
+				} else {
+					logger.Infof("cannot find %s/recvAndDecompress for %s/http2/recv/dataFrame/loopyReader", opid, opid)
+				}
+			default:
+				flowEndID = -1
+			}
+
+			if flowEndID != -1 {
+				flowID := fmt.Sprintf("lrc begin:/%d%s end:/%d%s begin:(%d, %s, %s) end:(%d, %s, %s)", connectionCounter, stat.Timers[i].Tags, connectionCounter, stat.Timers[flowEndID].Tags, i, pid, tid, flowEndID, flowEndPID, flowEndTID)
+				result = append(result,
+					jsonNode{
+						Name:      fmt.Sprintf("%s/flow", opid),
+						Cat:       categories + ",flow",
+						ID:        flowID,
+						Cname:     hashCname("flow"),
+						Phase:     "s",
+						Timestamp: catapultNs(stat.Timers[i].EndSec-baseSec, stat.Timers[i].EndNsec-baseNsec),
+						PID:       pid,
+						TID:       tid,
+					},
+					jsonNode{
+						Name:      fmt.Sprintf("%s/flow", opid),
+						Cat:       categories + ",flow",
+						ID:        flowID,
+						Cname:     hashCname("flow"),
+						Phase:     "f",
+						Timestamp: catapultNs(stat.Timers[flowEndID].BeginSec-baseSec, stat.Timers[flowEndID].BeginNsec-baseNsec),
+						PID:       flowEndPID,
+						TID:       flowEndTID,
+					},
+				)
+			}
+		} else if stat.Timers[i].GoId == loopyWriterGoID {
+			pid, tid = fmt.Sprintf("/%s/%d/loopyWriter", stat.Tags, connectionCounter), fmt.Sprintf("%d", stat.Timers[i].GoId)
+
+			var flowBeginID int
+			var flowBeginPID, flowBeginTID string
+			switch stat.Timers[i].Tags {
+			case "/http2/recv/header/loopyWriter/registerOutStream":
+				flowBeginID = filterCounter(stat, "/http2/recv/header", lwc.GetAndInc("/http2/recv/header/loopyWriter/registerOutStream"))
+				flowBeginPID = fmt.Sprintf("/%s/%d/loopyReader", stat.Tags, connectionCounter)
+				flowBeginTID = fmt.Sprintf("%d", loopyReaderGoID)
+			case "/http2/send/dataFrame/loopyWriter/preprocess":
+				flowBeginID = filterCounter(stat, "/transport/enqueue", lwc.GetAndInc("/http2/send/dataFrame/loopyWriter/preprocess"))
+				if flowBeginID != -1 {
+					flowBeginPID = opid
+					flowBeginTID = fmt.Sprintf("%d", stat.Timers[flowBeginID].GoId)
+				} else {
+					logger.Infof("cannot find /%d/transport/enqueue for /%d/http2/send/dataFrame/loopyWriter/preprocess", connectionCounter, connectionCounter)
+				}
+			default:
+				flowBeginID = -1
+			}
+
+			if flowBeginID != -1 {
+				flowID := fmt.Sprintf("lwc begin:/%d%s end:/%d%s begin:(%d, %s, %s) end:(%d, %s, %s)", connectionCounter, stat.Timers[flowBeginID].Tags, connectionCounter, stat.Timers[i].Tags, flowBeginID, flowBeginPID, flowBeginTID, i, pid, tid)
+				result = append(result,
+					jsonNode{
+						Name:      fmt.Sprintf("/%s/%d/%d/flow", stat.Tags, connectionCounter, streamID),
+						Cat:       categories + ",flow",
+						ID:        flowID,
+						Cname:     hashCname("flow"),
+						Phase:     "s",
+						Timestamp: catapultNs(stat.Timers[flowBeginID].EndSec-baseSec, stat.Timers[flowBeginID].EndNsec-baseNsec),
+						PID:       flowBeginPID,
+						TID:       flowBeginTID,
+					},
+					jsonNode{
+						Name:      fmt.Sprintf("/%s/%d/%d/flow", stat.Tags, connectionCounter, streamID),
+						Cat:       categories + ",flow",
+						ID:        flowID,
+						Cname:     hashCname("flow"),
+						Phase:     "f",
+						Timestamp: catapultNs(stat.Timers[i].BeginSec-baseSec, stat.Timers[i].BeginNsec-baseNsec),
+						PID:       pid,
+						TID:       tid,
+					},
+				)
+			}
+		}
+
+		result = append(result,
+			jsonNode{
+				Name:      fmt.Sprintf("%s%s", opid, stat.Timers[i].Tags),
+				Cat:       categories,
+				ID:        opid,
+				Cname:     hashCname(stat.Timers[i].Tags),
+				Phase:     "B",
+				Timestamp: catapultNs(stat.Timers[i].BeginSec-baseSec, stat.Timers[i].BeginNsec-baseNsec),
+				PID:       pid,
+				TID:       tid,
+			},
+			jsonNode{
+				Name:      fmt.Sprintf("%s%s", opid, stat.Timers[i].Tags),
+				Cat:       categories,
+				ID:        opid,
+				Cname:     hashCname(stat.Timers[i].Tags),
+				Phase:     "E",
+				Timestamp: catapultNs(stat.Timers[i].EndSec-baseSec, stat.Timers[i].EndNsec-baseNsec),
+				PID:       pid,
+				TID:       tid,
+			},
+		)
+	}
+
+	return result
+}
+
+// timerBeginIsBefore compares two proto Timer objects to determine if the
+// first comes before the second chronologically.
+func timerBeginIsBefore(ti *ppb.Timer, tj *ppb.Timer) bool {
+	if ti.BeginSec == tj.BeginSec {
+		return ti.BeginNsec < tj.BeginNsec
+	}
+	return ti.BeginSec < tj.BeginSec
+}
+
+// streamStatsCatapultJSON receives a *snapshot and the name of a JSON file to
+// write to. The grpc-go profiling snapshot is processed and converted to a
+// JSON format that can be understood by trace-viewer.
+func streamStatsCatapultJSON(s *snapshot, streamStatsCatapultJSONFileName string) (err error) {
+	logger.Infof("calculating stream stats filters")
+	filterArray := strings.Split(*flagStreamStatsFilter, ",")
+	filter := make(map[string]bool)
+	for _, f := range filterArray {
+		filter[f] = true
+	}
+
+	logger.Infof("filter stream stats for %s", *flagStreamStatsFilter)
+	var streamStats []*ppb.Stat
+	for _, stat := range s.StreamStats {
+		if _, ok := filter[stat.Tags]; ok {
+			streamStats = append(streamStats, stat)
+		}
+	}
+
+	logger.Infof("sorting timers within all stats")
+	for id := range streamStats {
+		sort.Slice(streamStats[id].Timers, func(i, j int) bool {
+			return timerBeginIsBefore(streamStats[id].Timers[i], streamStats[id].Timers[j])
+		})
+	}
+
+	logger.Infof("sorting stream stats")
+	sort.Slice(streamStats, func(i, j int) bool {
+		if len(streamStats[j].Timers) == 0 {
+			return true
+		} else if len(streamStats[i].Timers) == 0 {
+			return false
+		}
+		pi := binary.BigEndian.Uint64(streamStats[i].Metadata[0:8])
+		pj := binary.BigEndian.Uint64(streamStats[j].Metadata[0:8])
+		if pi == pj {
+			return timerBeginIsBefore(streamStats[i].Timers[0], streamStats[j].Timers[0])
+		}
+
+		return pi < pj
+	})
+
+	// Clip the last stat as it's from the /Profiling/GetStreamStats call that we
+	// made to retrieve the stats themselves. This likely happened millions of
+	// nanoseconds after the last stream we want to profile, so it'd just make
+	// the catapult graph less readable.
+	if len(streamStats) > 0 {
+		streamStats = streamStats[:len(streamStats)-1]
+	}
+
+	// All timestamps use the earliest timestamp available as the reference.
+	logger.Infof("calculating the earliest timestamp across all timers")
+	var base *ppb.Timer
+	for _, stat := range streamStats {
+		for _, timer := range stat.Timers {
+			if base == nil || timerBeginIsBefore(base, timer) {
+				base = timer
+			}
+		}
+	}
+
+	logger.Infof("converting %d stats to catapult JSON format", len(streamStats))
+	var jsonNodes []jsonNode
+	for _, stat := range streamStats {
+		jsonNodes = append(jsonNodes, streamStatsCatapultJSONSingle(stat, base.BeginSec, base.BeginNsec)...)
+	}
+
+	logger.Infof("marshalling catapult JSON")
+	b, err := json.Marshal(jsonNodes)
+	if err != nil {
+		logger.Errorf("cannot marshal JSON: %v", err)
+		return err
+	}
+
+	logger.Infof("creating catapult JSON file")
+	streamStatsCatapultJSONFile, err := os.Create(streamStatsCatapultJSONFileName)
+	if err != nil {
+		logger.Errorf("cannot create file %s: %v", streamStatsCatapultJSONFileName, err)
+		return err
+	}
+	defer streamStatsCatapultJSONFile.Close()
+
+	logger.Infof("writing catapult JSON to disk")
+	_, err = streamStatsCatapultJSONFile.Write(b)
+	if err != nil {
+		logger.Errorf("cannot write marshalled JSON: %v", err)
+		return err
+	}
+
+	logger.Infof("successfully wrote catapult JSON file %s", streamStatsCatapultJSONFileName)
+	return nil
+}

profiling/cmd/flags.go

@@ -0,0 +1,76 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * 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 main
+
+import (
+	"flag"
+	"fmt"
+)
+
+var flagAddress = flag.String("address", "", "address of a remote gRPC server with profiling turned on to retrieve stats from")
+var flagTimeout = flag.Int("timeout", 0, "network operations timeout in seconds to remote target (0 indicates unlimited)")
+
+var flagRetrieveSnapshot = flag.Bool("retrieve-snapshot", false, "connect to remote target and retrieve a profiling snapshot locally for processing")
+var flagSnapshot = flag.String("snapshot", "", "snapshot file to write to when retrieving profiling data or snapshot file to read from when processing profiling data")
+
+var flagEnableProfiling = flag.Bool("enable-profiling", false, "enable profiling in remote target")
+var flagDisableProfiling = flag.Bool("disable-profiling", false, "disable profiling in remote target")
+
+var flagStreamStatsCatapultJSON = flag.String("stream-stats-catapult-json", "", "path to a file to write to after transforming a snapshot into catapult's JSON format")
+var flagStreamStatsFilter = flag.String("stream-stats-filter", "server,client", "comma-separated list of stat tags to filter for")
+
+func exactlyOneOf(opts ...bool) bool {
+	first := true
+	for _, o := range opts {
+		if !o {
+			continue
+		}
+
+		if !first {
+			return false
+		}
+		first = false
+	}
+
+	return !first
+}
+
+func parseArgs() error {
+	flag.Parse()
+
+	if *flagAddress != "" {
+		if !exactlyOneOf(*flagEnableProfiling, *flagDisableProfiling, *flagRetrieveSnapshot) {
+			return fmt.Errorf("when -address is specified, you must include exactly only one of -enable-profiling, -disable-profiling, and -retrieve-snapshot")
+		}
+
+		if *flagStreamStatsCatapultJSON != "" {
+			return fmt.Errorf("when -address is specified, you must not include -stream-stats-catapult-json")
+		}
+	} else {
+		if *flagEnableProfiling || *flagDisableProfiling || *flagRetrieveSnapshot {
+			return fmt.Errorf("when -address isn't specified, you must not include any of -enable-profiling, -disable-profiling, and -retrieve-snapshot")
+		}
+
+		if *flagStreamStatsCatapultJSON == "" {
+			return fmt.Errorf("when -address isn't specified, you must include -stream-stats-catapult-json")
+		}
+	}
+
+	return nil
+}

profiling/cmd/local.go

@@ -0,0 +1,68 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * 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 main
+
+import (
+	"encoding/gob"
+	"fmt"
+	"os"
+)
+
+func loadSnapshot(snapshotFileName string) (*snapshot, error) {
+	logger.Infof("opening snapshot file %s", snapshotFileName)
+	snapshotFile, err := os.Open(snapshotFileName)
+	if err != nil {
+		logger.Errorf("cannot open %s: %v", snapshotFileName, err)
+		return nil, err
+	}
+	defer snapshotFile.Close()
+
+	logger.Infof("decoding snapshot file %s", snapshotFileName)
+	s := &snapshot{}
+	decoder := gob.NewDecoder(snapshotFile)
+	if err = decoder.Decode(s); err != nil {
+		logger.Errorf("cannot decode %s: %v", snapshotFileName, err)
+		return nil, err
+	}
+
+	return s, nil
+}
+
+func localCommand() error {
+	if *flagSnapshot == "" {
+		return fmt.Errorf("-snapshot flag missing")
+	}
+
+	s, err := loadSnapshot(*flagSnapshot)
+	if err != nil {
+		return err
+	}
+
+	if *flagStreamStatsCatapultJSON == "" {
+		return fmt.Errorf("snapshot file specified without an action to perform")
+	}
+
+	if *flagStreamStatsCatapultJSON != "" {
+		if err = streamStatsCatapultJSON(s, *flagStreamStatsCatapultJSON); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

profiling/cmd/main.go

@@ -0,0 +1,53 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * 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.
+ *
+ */
+
+// Binary cmd is a command-line tool for profiling management. It retrieves and
+// processes data from the profiling service.
+package main
+
+import (
+	"os"
+
+	"google.golang.org/grpc/grpclog"
+	ppb "google.golang.org/grpc/profiling/proto"
+)
+
+var logger = grpclog.Component("profiling")
+
+type snapshot struct {
+	StreamStats []*ppb.Stat
+}
+
+func main() {
+	if err := parseArgs(); err != nil {
+		logger.Errorf("error parsing flags: %v", err)
+		os.Exit(1)
+	}
+
+	if *flagAddress != "" {
+		if err := remoteCommand(); err != nil {
+			logger.Errorf("error: %v", err)
+			os.Exit(1)
+		}
+	} else {
+		if err := localCommand(); err != nil {
+			logger.Errorf("error: %v", err)
+			os.Exit(1)
+		}
+	}
+}

profiling/cmd/remote.go

@@ -0,0 +1,98 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * 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 main
+
+import (
+	"context"
+	"encoding/gob"
+	"fmt"
+	"os"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+	ppb "google.golang.org/grpc/profiling/proto"
+)
+
+func setEnabled(ctx context.Context, c ppb.ProfilingClient, enabled bool) error {
+	_, err := c.Enable(ctx, &ppb.EnableRequest{Enabled: enabled})
+	if err != nil {
+		logger.Infof("error calling Enable: %v\n", err)
+		return err
+	}
+
+	logger.Infof("successfully set enabled = %v", enabled)
+	return nil
+}
+
+func retrieveSnapshot(ctx context.Context, c ppb.ProfilingClient, f string) error {
+	logger.Infof("getting stream stats")
+	resp, err := c.GetStreamStats(ctx, &ppb.GetStreamStatsRequest{})
+	if err != nil {
+		logger.Errorf("error calling GetStreamStats: %v\n", err)
+		return err
+	}
+	s := &snapshot{StreamStats: resp.StreamStats}
+
+	logger.Infof("creating snapshot file %s", f)
+	file, err := os.Create(f)
+	if err != nil {
+		logger.Errorf("cannot create %s: %v", f, err)
+		return err
+	}
+	defer file.Close()
+
+	logger.Infof("encoding data and writing to snapshot file %s", f)
+	encoder := gob.NewEncoder(file)
+	err = encoder.Encode(s)
+	if err != nil {
+		logger.Infof("error encoding: %v", err)
+		return err
+	}
+
+	logger.Infof("successfully wrote profiling snapshot to %s", f)
+	return nil
+}
+
+func remoteCommand() error {
+	ctx := context.Background()
+	if *flagTimeout > 0 {
+		var cancel func()
+		ctx, cancel = context.WithTimeout(context.Background(), time.Duration(*flagTimeout)*time.Second)
+		defer cancel()
+	}
+
+	logger.Infof("dialing %s", *flagAddress)
+	cc, err := grpc.NewClient(*flagAddress, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	if err != nil {
+		logger.Fatalf("grpc.NewClient(%q) = %v", *flagAddress, err)
+		return err
+	}
+	defer cc.Close()
+
+	c := ppb.NewProfilingClient(cc)
+
+	if *flagEnableProfiling || *flagDisableProfiling {
+		return setEnabled(ctx, c, *flagEnableProfiling)
+	}
+	if *flagRetrieveSnapshot {
+		return retrieveSnapshot(ctx, c, *flagSnapshot)
+	}
+	return fmt.Errorf("what should I do with the remote target?")
+}