Show fuse ops as spans in traced contexts. Plumb through in tests.

connection.go

@@ -21,6 +21,8 @@ import (
 	"runtime"
 	"sync"
 
+	"golang.org/x/net/context"
+
 	"github.com/jacobsa/bazilfuse"
 	"github.com/jacobsa/fuse/fuseops"
 )
@@ -31,6 +33,9 @@ type Connection struct {
 	wrapped     *bazilfuse.Conn
 	opsInFlight sync.WaitGroup
 
+	// The context from which all op contexts inherit.
+	parentCtx context.Context
+
 	// For logging purposes only.
 	nextOpID uint32
 }
@@ -38,11 +43,13 @@ type Connection struct {
 // Responsibility for closing the wrapped connection is transferred to the
 // result. You must call c.close() eventually.
 func newConnection(
+	parentCtx context.Context,
 	logger *log.Logger,
 	wrapped *bazilfuse.Conn) (c *Connection, err error) {
 	c = &Connection{
-		logger:  logger,
-		wrapped: wrapped,
+		logger:    logger,
+		wrapped:   wrapped,
+		parentCtx: parentCtx,
 	}
 
 	return
@@ -115,7 +122,8 @@ func (c *Connection) ReadOp() (op fuseops.Op, err error) {
 			c.log(opID, calldepth+1, format, v...)
 		}
 
-		if op = fuseops.Convert(bfReq, logForOp, &c.opsInFlight); op == nil {
+		op = fuseops.Convert(c.parentCtx, bfReq, logForOp, &c.opsInFlight)
+		if op == nil {
 			c.log(opID, 1, "-> ENOSYS: %v", bfReq)
 			bfReq.RespondError(ENOSYS)
 			continue

fuseops/common_op.go

@@ -16,31 +16,56 @@ package fuseops
 
 import (
 	"reflect"
+	"strings"
 	"sync"
 
 	"github.com/jacobsa/bazilfuse"
+	"github.com/jacobsa/reqtrace"
 	"golang.org/x/net/context"
 )
 
 // A helper for embedding common behavior.
 type commonOp struct {
 	opType      string
-	ctx         context.Context
 	r           bazilfuse.Request
 	log         func(int, string, ...interface{})
 	opsInFlight *sync.WaitGroup
+
+	ctx    context.Context
+	report reqtrace.ReportFunc
+}
+
+func describeOpType(t reflect.Type) (desc string) {
+	name := t.String()
+
+	// The usual case: a string that looks like "*fuseops.GetInodeAttributesOp".
+	const prefix = "*fuseops."
+	const suffix = "Op"
+	if strings.HasPrefix(name, prefix) && strings.HasSuffix(name, suffix) {
+		desc = name[len(prefix) : len(name)-len(suffix)]
+		return
+	}
+
+	// Otherwise, it's not clear what to do.
+	desc = t.String()
+
+	return
 }
 
 func (o *commonOp) init(
-	opType string,
+	ctx context.Context,
+	opType reflect.Type,
 	r bazilfuse.Request,
 	log func(int, string, ...interface{}),
 	opsInFlight *sync.WaitGroup) {
-	o.opType = opType
-	o.ctx = context.Background()
+	// Initialize basic fields.
+	o.opType = describeOpType(opType)
 	o.r = r
 	o.log = log
 	o.opsInFlight = opsInFlight
+
+	// Set up a trace span for this op.
+	o.ctx, o.report = reqtrace.StartSpan(ctx, o.opType)
 }
 
 func (o *commonOp) Header() OpHeader {
@@ -65,6 +90,8 @@ func (o *commonOp) respondErr(err error) {
 		panic("Expect non-nil here.")
 	}
 
+	o.report(err)
+
 	o.Logf(
 		"-> (%s) error: %v",
 		o.opType,
@@ -78,6 +105,9 @@ func (o *commonOp) respondErr(err error) {
 //
 // Special case: nil means o.r.Respond accepts no parameters.
 func (o *commonOp) respond(resp interface{}) {
+	// We were successful.
+	o.report(nil)
+
 	// Find the Respond method.
 	v := reflect.ValueOf(o.r)
 	respond := v.MethodByName("Respond")

fuseops/convert.go

@@ -19,6 +19,8 @@ import (
 	"sync"
 	"time"
 
+	"golang.org/x/net/context"
+
 	"github.com/jacobsa/bazilfuse"
 )
 
@@ -28,6 +30,7 @@ import (
 // This function is an implementation detail of the fuse package, and must not
 // be called by anyone else.
 func Convert(
+	parentCtx context.Context,
 	r bazilfuse.Request,
 	logForOp func(int, string, ...interface{}),
 	opsInFlight *sync.WaitGroup) (o Op) {
@@ -213,7 +216,7 @@ func Convert(
 		return
 	}
 
-	co.init(reflect.TypeOf(o).String(), r, logForOp, opsInFlight)
+	co.init(parentCtx, reflect.TypeOf(o), r, logForOp, opsInFlight)
 	return
 }
 

mounted_file_system.go

@@ -61,6 +61,10 @@ func (mfs *MountedFileSystem) Join(ctx context.Context) error {
 
 // Optional configuration accepted by Mount.
 type MountConfig struct {
+	// The context from which every op read from the connetion by the sever
+	// should inherit. If nil, context.Background() will be used.
+	OpContext context.Context
+
 	// OS X only.
 	//
 	// Normally on OS X we mount with the novncache option
@@ -127,8 +131,14 @@ func Mount(
 		return
 	}
 
+	// Choose a parent context for ops.
+	opContext := config.OpContext
+	if opContext == nil {
+		opContext = context.Background()
+	}
+
 	// Create our own Connection object wrapping it.
-	connection, err := newConnection(logger, bfConn)
+	connection, err := newConnection(opContext, logger, bfConn)
 	if err != nil {
 		bfConn.Close()
 		err = fmt.Errorf("newConnection: %v", err)

samples/in_process.go

@@ -59,7 +59,7 @@ type SampleTest struct {
 //
 // REQUIRES: t.Server has been set.
 func (t *SampleTest) SetUp(ti *ogletest.TestInfo) {
-	err := t.initialize(t.Server, &t.MountConfig)
+	err := t.initialize(ti.Ctx, t.Server, &t.MountConfig)
 	if err != nil {
 		panic(err)
 	}
@@ -67,10 +67,17 @@ func (t *SampleTest) SetUp(ti *ogletest.TestInfo) {
 
 // Like SetUp, but doens't panic.
 func (t *SampleTest) initialize(
+	ctx context.Context,
 	server fuse.Server,
 	config *fuse.MountConfig) (err error) {
-	// Initialize the context.
-	t.Ctx = context.Background()
+	// Initialize the context used by the test.
+	t.Ctx = ctx
+
+	// Make the server share that context, if the test hasn't already set some
+	// other one.
+	if config.OpContext == nil {
+		config.OpContext = ctx
+	}
 
 	// Initialize the clock.
 	t.Clock.SetTime(time.Date(2012, 8, 15, 22, 56, 0, 0, time.Local))

samples/subprocess.go

@@ -68,7 +68,7 @@ type SubprocessTest struct {
 // Mount the file system and initialize the other exported fields of the
 // struct. Panics on error.
 func (t *SubprocessTest) SetUp(ti *ogletest.TestInfo) {
-	err := t.initialize()
+	err := t.initialize(ti.Ctx)
 	if err != nil {
 		panic(err)
 	}
@@ -184,9 +184,9 @@ func waitForReady(readyReader *os.File, c chan<- struct{}) {
 }
 
 // Like SetUp, but doens't panic.
-func (t *SubprocessTest) initialize() (err error) {
+func (t *SubprocessTest) initialize(ctx context.Context) (err error) {
 	// Initialize the context.
-	t.Ctx = context.Background()
+	t.Ctx = ctx
 
 	// Set up a temporary directory.
 	t.Dir, err = ioutil.TempDir("", "sample_test")