htrace-htraced/go/src/org/apache/htrace/htraced/client_test.go - incubator-retired-htrace - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you 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 (
 	"fmt"
 	"github.com/ugorji/go/codec"
 	"math"
 	"math/rand"
 	htrace "org/apache/htrace/client"
 	"org/apache/htrace/common"
 	"org/apache/htrace/conf"
 	"org/apache/htrace/test"
 	"sort"
 	"sync"
 	"sync/atomic"
 	"testing"
 	"time"
 )

 func TestClientGetServerVersion(t *testing.T) {
 	htraceBld := &MiniHTracedBuilder{Name: "TestClientGetServerVersion",
 		DataDirs: make([]string, 2)}
 	ht, err := htraceBld.Build()
 	if err != nil {
 		t.Fatalf("failed to create datastore: %s", err.Error())
 	}
 	defer ht.Close()
 	var hcl *htrace.Client
 	hcl, err = htrace.NewClient(ht.ClientConf(), nil)
 	if err != nil {
 		t.Fatalf("failed to create client: %s", err.Error())
 	}
 	defer hcl.Close()
 	_, err = hcl.GetServerVersion()
 	if err != nil {
 		t.Fatalf("failed to call GetServerVersion: %s", err.Error())
 	}
 }

 func TestClientGetServerDebugInfo(t *testing.T) {
 	htraceBld := &MiniHTracedBuilder{Name: "TestClientGetServerDebugInfo",
 		DataDirs: make([]string, 2)}
 	ht, err := htraceBld.Build()
 	if err != nil {
 		t.Fatalf("failed to create datastore: %s", err.Error())
 	}
 	defer ht.Close()
 	var hcl *htrace.Client
 	hcl, err = htrace.NewClient(ht.ClientConf(), nil)
 	if err != nil {
 		t.Fatalf("failed to create client: %s", err.Error())
 	}
 	defer hcl.Close()
 	debugInfo, err := hcl.GetServerDebugInfo()
 	if err != nil {
 		t.Fatalf("failed to call GetServerDebugInfo: %s", err.Error())
 	}
 	if debugInfo.StackTraces == "" {
 		t.Fatalf(`debugInfo.StackTraces == ""`)
 	}
 	if debugInfo.GCStats == "" {
 		t.Fatalf(`debugInfo.GCStats == ""`)
 	}
 }

 func createRandomTestSpans(amount int) common.SpanSlice {
 	rnd := rand.New(rand.NewSource(2))
 	allSpans := make(common.SpanSlice, amount)
 	allSpans[0] = test.NewRandomSpan(rnd, allSpans[0:0])
 	for i := 1; i < amount; i++ {
 		allSpans[i] = test.NewRandomSpan(rnd, allSpans[1:i])
 	}
 	allSpans[1].SpanData.Parents = []common.SpanId{common.SpanId(allSpans[0].Id)}
 	return allSpans
 }

 func TestClientOperations(t *testing.T) {
 	htraceBld := &MiniHTracedBuilder{Name: "TestClientOperations",
 		DataDirs:     make([]string, 2),
 		WrittenSpans: common.NewSemaphore(0),
 	}
 	ht, err := htraceBld.Build()
 	if err != nil {
 		t.Fatalf("failed to create datastore: %s", err.Error())
 	}
 	defer ht.Close()
 	var hcl *htrace.Client
 	hcl, err = htrace.NewClient(ht.ClientConf(), nil)
 	if err != nil {
 		t.Fatalf("failed to create client: %s", err.Error())
 	}
 	defer hcl.Close()

 	// Create some random trace spans.
 	NUM_TEST_SPANS := 30
 	allSpans := createRandomTestSpans(NUM_TEST_SPANS)

 	// Write half of the spans to htraced via the client.
 	err = hcl.WriteSpans(allSpans[0 : NUM_TEST_SPANS/2])
 	if err != nil {
 		t.Fatalf("WriteSpans(0:%d) failed: %s\n", NUM_TEST_SPANS/2,
 			err.Error())
 	}
 	ht.Store.WrittenSpans.Waits(int64(NUM_TEST_SPANS / 2))

 	// Look up the first half of the spans.  They should be found.
 	var span *common.Span
 	for i := 0; i < NUM_TEST_SPANS/2; i++ {
 		span, err = hcl.FindSpan(allSpans[i].Id)
 		if err != nil {
 			t.Fatalf("FindSpan(%d) failed: %s\n", i, err.Error())
 		}
 		common.ExpectSpansEqual(t, allSpans[i], span)
 	}

 	// Look up the second half of the spans.  They should not be found.
 	for i := NUM_TEST_SPANS / 2; i < NUM_TEST_SPANS; i++ {
 		span, err = hcl.FindSpan(allSpans[i].Id)
 		if err != nil {
 			t.Fatalf("FindSpan(%d) failed: %s\n", i, err.Error())
 		}
 		if span != nil {
 			t.Fatalf("Unexpectedly found a span we never write to "+
 				"the server: FindSpan(%d) succeeded\n", i)
 		}
 	}

 	// Test FindChildren
 	childSpan := allSpans[1]
 	parentId := childSpan.Parents[0]
 	var children []common.SpanId
 	children, err = hcl.FindChildren(parentId, 1)
 	if err != nil {
 		t.Fatalf("FindChildren(%s) failed: %s\n", parentId, err.Error())
 	}
 	if len(children) != 1 {
 		t.Fatalf("FindChildren(%s) returned an invalid number of "+
 			"children: expected %d, got %d\n", parentId, 1, len(children))
 	}
 	if !children[0].Equal(childSpan.Id) {
 		t.Fatalf("FindChildren(%s) returned an invalid child id: expected %s, "+
 			" got %s\n", parentId, childSpan.Id, children[0])
 	}

 	// Test FindChildren on a span that has no children
 	childlessSpan := allSpans[NUM_TEST_SPANS/2]
 	children, err = hcl.FindChildren(childlessSpan.Id, 10)
 	if err != nil {
 		t.Fatalf("FindChildren(%d) failed: %s\n", childlessSpan.Id, err.Error())
 	}
 	if len(children) != 0 {
 		t.Fatalf("FindChildren(%d) returned an invalid number of "+
 			"children: expected %d, got %d\n", childlessSpan.Id, 0, len(children))
 	}

 	// Test Query
 	var query common.Query
 	query = common.Query{Lim: 10}
 	spans, err := hcl.Query(&query)
 	if err != nil {
 		t.Fatalf("Query({lim: %d}) failed: %s\n", 10, err.Error())
 	}
 	if len(spans) != 10 {
 		t.Fatalf("Query({lim: %d}) returned an invalid number of "+
 			"children: expected %d, got %d\n", 10, 10, len(spans))
 	}
 }

 func TestDumpAll(t *testing.T) {
 	htraceBld := &MiniHTracedBuilder{Name: "TestDumpAll",
 		DataDirs:     make([]string, 2),
 		WrittenSpans: common.NewSemaphore(0),
 		Cnf: map[string]string{
 			conf.HTRACE_LOG_LEVEL: "INFO",
 		},
 	}
 	ht, err := htraceBld.Build()
 	if err != nil {
 		t.Fatalf("failed to create datastore: %s", err.Error())
 	}
 	defer ht.Close()
 	var hcl *htrace.Client
 	hcl, err = htrace.NewClient(ht.ClientConf(), nil)
 	if err != nil {
 		t.Fatalf("failed to create client: %s", err.Error())
 	}
 	defer hcl.Close()

 	NUM_TEST_SPANS := 100
 	allSpans := createRandomTestSpans(NUM_TEST_SPANS)
 	sort.Sort(allSpans)
 	err = hcl.WriteSpans(allSpans)
 	if err != nil {
 		t.Fatalf("WriteSpans failed: %s\n", err.Error())
 	}
 	ht.Store.WrittenSpans.Waits(int64(NUM_TEST_SPANS))
 	out := make(chan *common.Span, NUM_TEST_SPANS)
 	var dumpErr error
 	go func() {
 		dumpErr = hcl.DumpAll(3, out)
 	}()
 	var numSpans int
 	nextLogTime := time.Now().Add(time.Millisecond * 5)
 	for {
 		span, channelOpen := <-out
 		if !channelOpen {
 			break
 		}
 		common.ExpectSpansEqual(t, allSpans[numSpans], span)
 		numSpans++
 		if testing.Verbose() {
 			now := time.Now()
 			if !now.Before(nextLogTime) {
 				nextLogTime = now
 				nextLogTime = nextLogTime.Add(time.Millisecond * 5)
 				fmt.Printf("read back %d span(s)...\n", numSpans)
 			}
 		}
 	}
 	if numSpans != len(allSpans) {
 		t.Fatalf("expected to read %d spans... but only read %d\n",
 			len(allSpans), numSpans)
 	}
 	if dumpErr != nil {
 		t.Fatalf("got dump error %s\n", dumpErr.Error())
 	}
 }

 const EXAMPLE_CONF_KEY = "example.conf.key"
 const EXAMPLE_CONF_VALUE = "foo.bar.baz"

 func TestClientGetServerConf(t *testing.T) {
 	htraceBld := &MiniHTracedBuilder{Name: "TestClientGetServerConf",
 		Cnf: map[string]string{
 			EXAMPLE_CONF_KEY: EXAMPLE_CONF_VALUE,
 		},
 		DataDirs: make([]string, 2)}
 	ht, err := htraceBld.Build()
 	if err != nil {
 		t.Fatalf("failed to create datastore: %s", err.Error())
 	}
 	defer ht.Close()
 	var hcl *htrace.Client
 	hcl, err = htrace.NewClient(ht.ClientConf(), nil)
 	if err != nil {
 		t.Fatalf("failed to create client: %s", err.Error())
 	}
 	defer hcl.Close()
 	serverCnf, err2 := hcl.GetServerConf()
 	if err2 != nil {
 		t.Fatalf("failed to call GetServerConf: %s", err2.Error())
 	}
 	if serverCnf[EXAMPLE_CONF_KEY] != EXAMPLE_CONF_VALUE {
 		t.Fatalf("unexpected value for %s: %s",
 			EXAMPLE_CONF_KEY, EXAMPLE_CONF_VALUE)
 	}
 }

 const TEST_NUM_HRPC_HANDLERS = 2

 const TEST_NUM_WRITESPANS = 4

 // Tests that HRPC limits the number of simultaneous connections being processed.
 func TestHrpcAdmissionsControl(t *testing.T) {
 	var wg sync.WaitGroup
 	wg.Add(TEST_NUM_WRITESPANS)
 	var numConcurrentHrpcCalls int32
 	testHooks := &hrpcTestHooks{
 		HandleAdmission: func() {
 			defer wg.Done()
 			n := atomic.AddInt32(&numConcurrentHrpcCalls, 1)
 			if n > TEST_NUM_HRPC_HANDLERS {
 				t.Fatalf("The number of concurrent HRPC calls went above "+
 					"%d: it's at %d\n", TEST_NUM_HRPC_HANDLERS, n)
 			}
 			time.Sleep(1 * time.Millisecond)
 			n = atomic.AddInt32(&numConcurrentHrpcCalls, -1)
 			if n >= TEST_NUM_HRPC_HANDLERS {
 				t.Fatalf("The number of concurrent HRPC calls went above "+
 					"%d: it was at %d\n", TEST_NUM_HRPC_HANDLERS, n+1)
 			}
 		},
 	}
 	htraceBld := &MiniHTracedBuilder{Name: "TestHrpcAdmissionsControl",
 		DataDirs: make([]string, 2),
 		Cnf: map[string]string{
 			conf.HTRACE_NUM_HRPC_HANDLERS: fmt.Sprintf("%d", TEST_NUM_HRPC_HANDLERS),
 		},
 		WrittenSpans:  common.NewSemaphore(0),
 		HrpcTestHooks: testHooks,
 	}
 	ht, err := htraceBld.Build()
 	if err != nil {
 		t.Fatalf("failed to create datastore: %s", err.Error())
 	}
 	defer ht.Close()
 	var hcl *htrace.Client
 	hcl, err = htrace.NewClient(ht.ClientConf(), nil)
 	if err != nil {
 		t.Fatalf("failed to create client: %s", err.Error())
 	}
 	// Create some random trace spans.
 	allSpans := createRandomTestSpans(TEST_NUM_WRITESPANS)
 	for iter := 0; iter < TEST_NUM_WRITESPANS; iter++ {
 		go func(i int) {
 			err = hcl.WriteSpans(allSpans[i : i+1])
 			if err != nil {
 				t.Fatalf("WriteSpans failed: %s\n", err.Error())
 			}
 		}(iter)
 	}
 	wg.Wait()
 	ht.Store.WrittenSpans.Waits(int64(TEST_NUM_WRITESPANS))
 }

 // Tests that HRPC I/O timeouts work.
 func TestHrpcIoTimeout(t *testing.T) {
 	htraceBld := &MiniHTracedBuilder{Name: "TestHrpcIoTimeout",
 		DataDirs: make([]string, 2),
 		Cnf: map[string]string{
 			conf.HTRACE_NUM_HRPC_HANDLERS:  fmt.Sprintf("%d", TEST_NUM_HRPC_HANDLERS),
 			conf.HTRACE_HRPC_IO_TIMEOUT_MS: "1",
 		},
 	}
 	ht, err := htraceBld.Build()
 	if err != nil {
 		t.Fatalf("failed to create datastore: %s", err.Error())
 	}
 	defer ht.Close()
 	var hcl *htrace.Client
 	finishClient := make(chan interface{})
 	defer func() {
 		// Close the finishClient channel, if it hasn't already been closed.
 		defer func() { recover() }()
 		close(finishClient)
 	}()
 	testHooks := &htrace.TestHooks{
 		HandleWriteRequestBody: func() {
 			<-finishClient
 		},
 	}
 	hcl, err = htrace.NewClient(ht.ClientConf(), testHooks)
 	if err != nil {
 		t.Fatalf("failed to create client: %s", err.Error())
 	}
 	// Create some random trace spans.
 	allSpans := createRandomTestSpans(TEST_NUM_WRITESPANS)
 	var wg sync.WaitGroup
 	wg.Add(TEST_NUM_WRITESPANS)
 	for iter := 0; iter < TEST_NUM_WRITESPANS; iter++ {
 		go func(i int) {
 			defer wg.Done()
 			// Ignore the error return because there are internal retries in
 			// the client which will make this succeed eventually, usually.
 			// Keep in mind that we only block until we have seen
 			// TEST_NUM_WRITESPANS I/O errors in the HRPC server-- after that,
 			// we let requests through so that the test can exit cleanly.
 			hcl.WriteSpans(allSpans[i : i+1])
 		}(iter)
 	}
 	for {
 		if ht.Hsv.GetNumIoErrors() >= TEST_NUM_WRITESPANS {
 			break
 		}
 		time.Sleep(1000 * time.Nanosecond)
 	}
 	close(finishClient)
 	wg.Wait()
 }

 func doWriteSpans(name string, N int, maxSpansPerRpc uint32, b *testing.B) {
 	htraceBld := &MiniHTracedBuilder{Name: "doWriteSpans",
 		Cnf: map[string]string{
 			conf.HTRACE_LOG_LEVEL: "INFO",
 			conf.HTRACE_NUM_HRPC_HANDLERS: "20",
 		},
 		WrittenSpans: common.NewSemaphore(int64(1 - N)),
 	}
 	ht, err := htraceBld.Build()
 	if err != nil {
 		panic(err)
 	}
 	defer ht.Close()
 	rnd := rand.New(rand.NewSource(1))
 	allSpans := make([]*common.Span, N)
 	for n := 0; n < N; n++ {
 		allSpans[n] = test.NewRandomSpan(rnd, allSpans[0:n])
 	}
 	// Determine how many calls to WriteSpans we should make.  Each writeSpans
 	// message should be small enough so that it doesn't exceed the max RPC
 	// body length limit.  TODO: a production-quality golang client would do
 	// this internally rather than needing us to do it here in the unit test.
 	bodyLen := (4 * common.MAX_HRPC_BODY_LENGTH) / 5
 	reqs := make([][]*common.Span, 0, 4)
 	curReq := -1
 	curReqLen := bodyLen
 	var curReqSpans uint32
 	mh := new(codec.MsgpackHandle)
 	mh.WriteExt = true
 	var mbuf [8192]byte
 	buf := mbuf[:0]
 	enc := codec.NewEncoderBytes(&buf, mh)
 	for n := 0; n < N; n++ {
 		span := allSpans[n]
 		if (curReqSpans >= maxSpansPerRpc) ||
 			(curReqLen >= bodyLen) {
 			reqs = append(reqs, make([]*common.Span, 0, 16))
 			curReqLen = 0
 			curReq++
 			curReqSpans = 0
 		}
 		buf = mbuf[:0]
 		enc.ResetBytes(&buf)
 		err := enc.Encode(span)
 		if err != nil {
 			panic(fmt.Sprintf("Error encoding span %s: %s\n",
 				span.String(), err.Error()))
 		}
 		bufLen := len(buf)
 		if bufLen > (bodyLen / 5) {
 			panic(fmt.Sprintf("Span too long at %d bytes\n", bufLen))
 		}
 		curReqLen += bufLen
 		reqs[curReq] = append(reqs[curReq], span)
 		curReqSpans++
 	}
 	ht.Store.lg.Infof("num spans: %d.  num WriteSpansReq calls: %d\n", N, len(reqs))
 	var hcl *htrace.Client
 	hcl, err = htrace.NewClient(ht.ClientConf(), nil)
 	if err != nil {
 		panic(fmt.Sprintf("failed to create client: %s", err.Error()))
 	}
 	defer hcl.Close()

 	// Reset the timer to avoid including the time required to create new
 	// random spans in the benchmark total.
 	if b != nil {
 		b.ResetTimer()
 	}

 	// Write many random spans.
 	for reqIdx := range reqs {
 		go func(i int) {
 			err = hcl.WriteSpans(reqs[i])
 			if err != nil {
 				panic(fmt.Sprintf("failed to send WriteSpans request %d: %s",
 					i, err.Error()))
 			}
 		}(reqIdx)
 	}
 	// Wait for all the spans to be written.
 	ht.Store.WrittenSpans.Wait()
 }

 // This is a test of how quickly we can create new spans via WriteSpans RPCs.
 // Like BenchmarkDatastoreWrites, it creates b.N spans in the datastore.
 // Unlike that benchmark, it sends the spans via RPC.
 // Suggested flags for running this:
 // -tags unsafe -cpu 16 -benchtime=1m
 func BenchmarkWriteSpans(b *testing.B) {
 	doWriteSpans("BenchmarkWriteSpans", b.N, math.MaxUint32, b)
 }

 func TestWriteSpansRpcs(t *testing.T) {
 	doWriteSpans("TestWriteSpansRpcs", 3000, 1000, nil)
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you 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 (
	"fmt"
	"github.com/ugorji/go/codec"
	"math"
	"math/rand"
	htrace "org/apache/htrace/client"
	"org/apache/htrace/common"
	"org/apache/htrace/conf"
	"org/apache/htrace/test"
	"sort"
	"sync"
	"sync/atomic"
	"testing"
	"time"
	)

	func TestClientGetServerVersion(t *testing.T) {
	htraceBld := &MiniHTracedBuilder{Name: "TestClientGetServerVersion",
	DataDirs: make([]string, 2)}
	ht, err := htraceBld.Build()
	if err != nil {
	t.Fatalf("failed to create datastore: %s", err.Error())
	}
	defer ht.Close()
	var hcl *htrace.Client
	hcl, err = htrace.NewClient(ht.ClientConf(), nil)
	if err != nil {
	t.Fatalf("failed to create client: %s", err.Error())
	}
	defer hcl.Close()
	_, err = hcl.GetServerVersion()
	if err != nil {
	t.Fatalf("failed to call GetServerVersion: %s", err.Error())
	}
	}

	func TestClientGetServerDebugInfo(t *testing.T) {
	htraceBld := &MiniHTracedBuilder{Name: "TestClientGetServerDebugInfo",
	DataDirs: make([]string, 2)}
	ht, err := htraceBld.Build()
	if err != nil {
	t.Fatalf("failed to create datastore: %s", err.Error())
	}
	defer ht.Close()
	var hcl *htrace.Client
	hcl, err = htrace.NewClient(ht.ClientConf(), nil)
	if err != nil {
	t.Fatalf("failed to create client: %s", err.Error())
	}
	defer hcl.Close()
	debugInfo, err := hcl.GetServerDebugInfo()
	if err != nil {
	t.Fatalf("failed to call GetServerDebugInfo: %s", err.Error())
	}
	if debugInfo.StackTraces == "" {
	t.Fatalf(`debugInfo.StackTraces == ""`)
	}
	if debugInfo.GCStats == "" {
	t.Fatalf(`debugInfo.GCStats == ""`)
	}
	}

	func createRandomTestSpans(amount int) common.SpanSlice {
	rnd := rand.New(rand.NewSource(2))
	allSpans := make(common.SpanSlice, amount)
	allSpans[0] = test.NewRandomSpan(rnd, allSpans[0:0])
	for i := 1; i < amount; i++ {
	allSpans[i] = test.NewRandomSpan(rnd, allSpans[1:i])
	}
	allSpans[1].SpanData.Parents = []common.SpanId{common.SpanId(allSpans[0].Id)}
	return allSpans
	}

	func TestClientOperations(t *testing.T) {
	htraceBld := &MiniHTracedBuilder{Name: "TestClientOperations",
	DataDirs: make([]string, 2),
	WrittenSpans: common.NewSemaphore(0),
	}
	ht, err := htraceBld.Build()
	if err != nil {
	t.Fatalf("failed to create datastore: %s", err.Error())
	}
	defer ht.Close()
	var hcl *htrace.Client
	hcl, err = htrace.NewClient(ht.ClientConf(), nil)
	if err != nil {
	t.Fatalf("failed to create client: %s", err.Error())
	}
	defer hcl.Close()

	// Create some random trace spans.
	NUM_TEST_SPANS := 30
	allSpans := createRandomTestSpans(NUM_TEST_SPANS)

	// Write half of the spans to htraced via the client.
	err = hcl.WriteSpans(allSpans[0 : NUM_TEST_SPANS/2])
	if err != nil {
	t.Fatalf("WriteSpans(0:%d) failed: %s\n", NUM_TEST_SPANS/2,
	err.Error())
	}
	ht.Store.WrittenSpans.Waits(int64(NUM_TEST_SPANS / 2))

	// Look up the first half of the spans. They should be found.
	var span *common.Span
	for i := 0; i < NUM_TEST_SPANS/2; i++ {
	span, err = hcl.FindSpan(allSpans[i].Id)
	if err != nil {
	t.Fatalf("FindSpan(%d) failed: %s\n", i, err.Error())
	}
	common.ExpectSpansEqual(t, allSpans[i], span)
	}

	// Look up the second half of the spans. They should not be found.
	for i := NUM_TEST_SPANS / 2; i < NUM_TEST_SPANS; i++ {
	span, err = hcl.FindSpan(allSpans[i].Id)
	if err != nil {
	t.Fatalf("FindSpan(%d) failed: %s\n", i, err.Error())
	}
	if span != nil {
	t.Fatalf("Unexpectedly found a span we never write to "+
	"the server: FindSpan(%d) succeeded\n", i)
	}
	}

	// Test FindChildren
	childSpan := allSpans[1]
	parentId := childSpan.Parents[0]
	var children []common.SpanId
	children, err = hcl.FindChildren(parentId, 1)
	if err != nil {
	t.Fatalf("FindChildren(%s) failed: %s\n", parentId, err.Error())
	}
	if len(children) != 1 {
	t.Fatalf("FindChildren(%s) returned an invalid number of "+
	"children: expected %d, got %d\n", parentId, 1, len(children))
	}
	if !children[0].Equal(childSpan.Id) {
	t.Fatalf("FindChildren(%s) returned an invalid child id: expected %s, "+
	" got %s\n", parentId, childSpan.Id, children[0])
	}

	// Test FindChildren on a span that has no children
	childlessSpan := allSpans[NUM_TEST_SPANS/2]
	children, err = hcl.FindChildren(childlessSpan.Id, 10)
	if err != nil {
	t.Fatalf("FindChildren(%d) failed: %s\n", childlessSpan.Id, err.Error())
	}
	if len(children) != 0 {
	t.Fatalf("FindChildren(%d) returned an invalid number of "+
	"children: expected %d, got %d\n", childlessSpan.Id, 0, len(children))
	}

	// Test Query
	var query common.Query
	query = common.Query{Lim: 10}
	spans, err := hcl.Query(&query)
	if err != nil {
	t.Fatalf("Query({lim: %d}) failed: %s\n", 10, err.Error())
	}
	if len(spans) != 10 {
	t.Fatalf("Query({lim: %d}) returned an invalid number of "+
	"children: expected %d, got %d\n", 10, 10, len(spans))
	}
	}

	func TestDumpAll(t *testing.T) {
	htraceBld := &MiniHTracedBuilder{Name: "TestDumpAll",
	DataDirs: make([]string, 2),
	WrittenSpans: common.NewSemaphore(0),
	Cnf: map[string]string{
	conf.HTRACE_LOG_LEVEL: "INFO",
	},
	}
	ht, err := htraceBld.Build()
	if err != nil {
	t.Fatalf("failed to create datastore: %s", err.Error())
	}
	defer ht.Close()
	var hcl *htrace.Client
	hcl, err = htrace.NewClient(ht.ClientConf(), nil)
	if err != nil {
	t.Fatalf("failed to create client: %s", err.Error())
	}
	defer hcl.Close()

	NUM_TEST_SPANS := 100
	allSpans := createRandomTestSpans(NUM_TEST_SPANS)
	sort.Sort(allSpans)
	err = hcl.WriteSpans(allSpans)
	if err != nil {
	t.Fatalf("WriteSpans failed: %s\n", err.Error())
	}
	ht.Store.WrittenSpans.Waits(int64(NUM_TEST_SPANS))
	out := make(chan *common.Span, NUM_TEST_SPANS)
	var dumpErr error
	go func() {
	dumpErr = hcl.DumpAll(3, out)
	}()
	var numSpans int
	nextLogTime := time.Now().Add(time.Millisecond * 5)
	for {
	span, channelOpen := <-out
	if !channelOpen {
	break
	}
	common.ExpectSpansEqual(t, allSpans[numSpans], span)
	numSpans++
	if testing.Verbose() {
	now := time.Now()
	if !now.Before(nextLogTime) {
	nextLogTime = now
	nextLogTime = nextLogTime.Add(time.Millisecond * 5)
	fmt.Printf("read back %d span(s)...\n", numSpans)
	}
	}
	}
	if numSpans != len(allSpans) {
	t.Fatalf("expected to read %d spans... but only read %d\n",
	len(allSpans), numSpans)
	}
	if dumpErr != nil {
	t.Fatalf("got dump error %s\n", dumpErr.Error())
	}
	}

	const EXAMPLE_CONF_KEY = "example.conf.key"
	const EXAMPLE_CONF_VALUE = "foo.bar.baz"

	func TestClientGetServerConf(t *testing.T) {
	htraceBld := &MiniHTracedBuilder{Name: "TestClientGetServerConf",
	Cnf: map[string]string{
	EXAMPLE_CONF_KEY: EXAMPLE_CONF_VALUE,
	},
	DataDirs: make([]string, 2)}
	ht, err := htraceBld.Build()
	if err != nil {
	t.Fatalf("failed to create datastore: %s", err.Error())
	}
	defer ht.Close()
	var hcl *htrace.Client
	hcl, err = htrace.NewClient(ht.ClientConf(), nil)
	if err != nil {
	t.Fatalf("failed to create client: %s", err.Error())
	}
	defer hcl.Close()
	serverCnf, err2 := hcl.GetServerConf()
	if err2 != nil {
	t.Fatalf("failed to call GetServerConf: %s", err2.Error())
	}
	if serverCnf[EXAMPLE_CONF_KEY] != EXAMPLE_CONF_VALUE {
	t.Fatalf("unexpected value for %s: %s",
	EXAMPLE_CONF_KEY, EXAMPLE_CONF_VALUE)
	}
	}

	const TEST_NUM_HRPC_HANDLERS = 2

	const TEST_NUM_WRITESPANS = 4

	// Tests that HRPC limits the number of simultaneous connections being processed.
	func TestHrpcAdmissionsControl(t *testing.T) {
	var wg sync.WaitGroup
	wg.Add(TEST_NUM_WRITESPANS)
	var numConcurrentHrpcCalls int32
	testHooks := &hrpcTestHooks{
	HandleAdmission: func() {
	defer wg.Done()
	n := atomic.AddInt32(&numConcurrentHrpcCalls, 1)
	if n > TEST_NUM_HRPC_HANDLERS {
	t.Fatalf("The number of concurrent HRPC calls went above "+
	"%d: it's at %d\n", TEST_NUM_HRPC_HANDLERS, n)
	}
	time.Sleep(1 * time.Millisecond)
	n = atomic.AddInt32(&numConcurrentHrpcCalls, -1)
	if n >= TEST_NUM_HRPC_HANDLERS {
	t.Fatalf("The number of concurrent HRPC calls went above "+
	"%d: it was at %d\n", TEST_NUM_HRPC_HANDLERS, n+1)
	}
	},
	}
	htraceBld := &MiniHTracedBuilder{Name: "TestHrpcAdmissionsControl",
	DataDirs: make([]string, 2),
	Cnf: map[string]string{
	conf.HTRACE_NUM_HRPC_HANDLERS: fmt.Sprintf("%d", TEST_NUM_HRPC_HANDLERS),
	},
	WrittenSpans: common.NewSemaphore(0),
	HrpcTestHooks: testHooks,
	}
	ht, err := htraceBld.Build()
	if err != nil {
	t.Fatalf("failed to create datastore: %s", err.Error())
	}
	defer ht.Close()
	var hcl *htrace.Client
	hcl, err = htrace.NewClient(ht.ClientConf(), nil)
	if err != nil {
	t.Fatalf("failed to create client: %s", err.Error())
	}
	// Create some random trace spans.
	allSpans := createRandomTestSpans(TEST_NUM_WRITESPANS)
	for iter := 0; iter < TEST_NUM_WRITESPANS; iter++ {
	go func(i int) {
	err = hcl.WriteSpans(allSpans[i : i+1])
	if err != nil {
	t.Fatalf("WriteSpans failed: %s\n", err.Error())
	}
	}(iter)
	}
	wg.Wait()
	ht.Store.WrittenSpans.Waits(int64(TEST_NUM_WRITESPANS))
	}

	// Tests that HRPC I/O timeouts work.
	func TestHrpcIoTimeout(t *testing.T) {
	htraceBld := &MiniHTracedBuilder{Name: "TestHrpcIoTimeout",
	DataDirs: make([]string, 2),
	Cnf: map[string]string{
	conf.HTRACE_NUM_HRPC_HANDLERS: fmt.Sprintf("%d", TEST_NUM_HRPC_HANDLERS),
	conf.HTRACE_HRPC_IO_TIMEOUT_MS: "1",
	},
	}
	ht, err := htraceBld.Build()
	if err != nil {
	t.Fatalf("failed to create datastore: %s", err.Error())
	}
	defer ht.Close()
	var hcl *htrace.Client
	finishClient := make(chan interface{})
	defer func() {
	// Close the finishClient channel, if it hasn't already been closed.
	defer func() { recover() }()
	close(finishClient)
	}()
	testHooks := &htrace.TestHooks{
	HandleWriteRequestBody: func() {
	<-finishClient
	},
	}
	hcl, err = htrace.NewClient(ht.ClientConf(), testHooks)
	if err != nil {
	t.Fatalf("failed to create client: %s", err.Error())
	}
	// Create some random trace spans.
	allSpans := createRandomTestSpans(TEST_NUM_WRITESPANS)
	var wg sync.WaitGroup
	wg.Add(TEST_NUM_WRITESPANS)
	for iter := 0; iter < TEST_NUM_WRITESPANS; iter++ {
	go func(i int) {
	defer wg.Done()
	// Ignore the error return because there are internal retries in
	// the client which will make this succeed eventually, usually.
	// Keep in mind that we only block until we have seen
	// TEST_NUM_WRITESPANS I/O errors in the HRPC server-- after that,
	// we let requests through so that the test can exit cleanly.
	hcl.WriteSpans(allSpans[i : i+1])
	}(iter)
	}
	for {
	if ht.Hsv.GetNumIoErrors() >= TEST_NUM_WRITESPANS {
	break
	}
	time.Sleep(1000 * time.Nanosecond)
	}
	close(finishClient)
	wg.Wait()
	}

	func doWriteSpans(name string, N int, maxSpansPerRpc uint32, b *testing.B) {
	htraceBld := &MiniHTracedBuilder{Name: "doWriteSpans",
	Cnf: map[string]string{
	conf.HTRACE_LOG_LEVEL: "INFO",
	conf.HTRACE_NUM_HRPC_HANDLERS: "20",
	},
	WrittenSpans: common.NewSemaphore(int64(1 - N)),
	}
	ht, err := htraceBld.Build()
	if err != nil {
	panic(err)
	}
	defer ht.Close()
	rnd := rand.New(rand.NewSource(1))
	allSpans := make([]*common.Span, N)
	for n := 0; n < N; n++ {
	allSpans[n] = test.NewRandomSpan(rnd, allSpans[0:n])
	}
	// Determine how many calls to WriteSpans we should make. Each writeSpans
	// message should be small enough so that it doesn't exceed the max RPC
	// body length limit. TODO: a production-quality golang client would do
	// this internally rather than needing us to do it here in the unit test.
	bodyLen := (4 * common.MAX_HRPC_BODY_LENGTH) / 5
	reqs := make([][]*common.Span, 0, 4)
	curReq := -1
	curReqLen := bodyLen
	var curReqSpans uint32
	mh := new(codec.MsgpackHandle)
	mh.WriteExt = true
	var mbuf [8192]byte
	buf := mbuf[:0]
	enc := codec.NewEncoderBytes(&buf, mh)
	for n := 0; n < N; n++ {
	span := allSpans[n]
	if (curReqSpans >= maxSpansPerRpc) \|\|
	(curReqLen >= bodyLen) {
	reqs = append(reqs, make([]*common.Span, 0, 16))
	curReqLen = 0
	curReq++
	curReqSpans = 0
	}
	buf = mbuf[:0]
	enc.ResetBytes(&buf)
	err := enc.Encode(span)
	if err != nil {
	panic(fmt.Sprintf("Error encoding span %s: %s\n",
	span.String(), err.Error()))
	}
	bufLen := len(buf)
	if bufLen > (bodyLen / 5) {
	panic(fmt.Sprintf("Span too long at %d bytes\n", bufLen))
	}
	curReqLen += bufLen
	reqs[curReq] = append(reqs[curReq], span)
	curReqSpans++
	}
	ht.Store.lg.Infof("num spans: %d. num WriteSpansReq calls: %d\n", N, len(reqs))
	var hcl *htrace.Client
	hcl, err = htrace.NewClient(ht.ClientConf(), nil)
	if err != nil {
	panic(fmt.Sprintf("failed to create client: %s", err.Error()))
	}
	defer hcl.Close()

	// Reset the timer to avoid including the time required to create new
	// random spans in the benchmark total.
	if b != nil {
	b.ResetTimer()
	}

	// Write many random spans.
	for reqIdx := range reqs {
	go func(i int) {
	err = hcl.WriteSpans(reqs[i])
	if err != nil {
	panic(fmt.Sprintf("failed to send WriteSpans request %d: %s",
	i, err.Error()))
	}
	}(reqIdx)
	}
	// Wait for all the spans to be written.
	ht.Store.WrittenSpans.Wait()
	}

	// This is a test of how quickly we can create new spans via WriteSpans RPCs.
	// Like BenchmarkDatastoreWrites, it creates b.N spans in the datastore.
	// Unlike that benchmark, it sends the spans via RPC.
	// Suggested flags for running this:
	// -tags unsafe -cpu 16 -benchtime=1m
	func BenchmarkWriteSpans(b *testing.B) {
	doWriteSpans("BenchmarkWriteSpans", b.N, math.MaxUint32, b)
	}

	func TestWriteSpansRpcs(t *testing.T) {
	doWriteSpans("TestWriteSpansRpcs", 3000, 1000, nil)
	}