Killed a few stale features and removed a global debug flag.

For GoogleCloudPlatform/gcsfuse#89.

connection.go

@@ -15,29 +15,18 @@
 package fuse
 
 import (
-	"flag"
 	"fmt"
 	"log"
 	"path"
 	"runtime"
 	"sync"
-	"time"
 
 	"golang.org/x/net/context"
-	"golang.org/x/sys/unix"
 
 	"github.com/jacobsa/bazilfuse"
 	"github.com/jacobsa/fuse/fuseops"
-	"github.com/jacobsa/reqtrace"
 )
 
-var fTraceByPID = flag.Bool(
-	"fuse.trace_by_pid",
-	false,
-	"Enable a hacky mode that uses reqtrace to group all ops from each "+
-		"individual PID. Not a good idea to use in production; races, bugs, and "+
-		"resource leaks likely lurk.")
-
 // A connection to the fuse kernel process.
 type Connection struct {
 	debugLogger *log.Logger
@@ -57,11 +46,6 @@ type Connection struct {
 	//
 	// GUARDED_BY(mu)
 	cancelFuncs map[bazilfuse.RequestID]func()
-
-	// A map from PID to a traced context for that PID.
-	//
-	// GUARDED_BY(mu)
-	pidMap map[int]context.Context
 }
 
 // Responsibility for closing the wrapped connection is transferred to the
@@ -77,7 +61,6 @@ func newConnection(
 		wrapped:     wrapped,
 		parentCtx:   parentCtx,
 		cancelFuncs: make(map[bazilfuse.RequestID]func()),
-		pidMap:      make(map[int]context.Context),
 	}
 
 	return
@@ -127,85 +110,6 @@ func (c *Connection) recordCancelFunc(
 	c.cancelFuncs[reqID] = f
 }
 
-// Wait until the process completes, then close off the trace and remove the
-// context from the map.
-//
-// LOCKS_EXCLUDED(c.mu)
-func (c *Connection) reportWhenPIDGone(
-	pid int,
-	ctx context.Context,
-	report reqtrace.ReportFunc) {
-	// HACK(jacobsa): Poll until the process no longer exists.
-	const pollPeriod = 50 * time.Millisecond
-	for {
-		// The man page for kill(2) says that if the signal is zero, then "no
-		// signal is sent, but error checking is still performed; this can be used
-		// to check for the existence of a process ID".
-		err := unix.Kill(pid, 0)
-
-		// ESRCH means the process is gone.
-		if err == unix.ESRCH {
-			break
-		}
-
-		// If we receive EPERM, we're not going to be able to do what we want. We
-		// don't really have any choice but to print info and leak.
-		if err == unix.EPERM {
-			log.Printf("Failed to kill(2) PID %v; no permissions. Leaking trace.", pid)
-			return
-		}
-
-		// Otherwise, panic.
-		if err != nil {
-			panic(fmt.Errorf("Kill(%v): %v", pid, err))
-		}
-
-		time.Sleep(pollPeriod)
-	}
-
-	// Finish up.
-	report(nil)
-
-	c.mu.Lock()
-	delete(c.pidMap, pid)
-	c.mu.Unlock()
-}
-
-// Set up a hacky per-PID trace context, if enabled. Either way, return a
-// context from which an operation should inherit.
-//
-// See notes on fTraceByPID.
-//
-// LOCKS_EXCLUDED(c.mu)
-func (c *Connection) maybeTraceByPID(
-	pid int) (ctx context.Context) {
-	ctx = c.parentCtx
-
-	// Is there anything to do?
-	if !reqtrace.Enabled() || !*fTraceByPID {
-		return
-	}
-
-	c.mu.Lock()
-	defer c.mu.Unlock()
-
-	// Do we already have a traced context for this PID?
-	if existing, ok := c.pidMap[pid]; ok {
-		ctx = existing
-		return
-	}
-
-	// Set up a new one and stick it in the map.
-	var report reqtrace.ReportFunc
-	ctx, report = reqtrace.Trace(ctx, fmt.Sprintf("Requests from PID %v", pid))
-	c.pidMap[pid] = ctx
-
-	// Ensure we close the trace and remove it from the map eventually.
-	go c.reportWhenPIDGone(pid, ctx, report)
-
-	return
-}
-
 // Set up state for an op that is about to be returned to the user, given its
 // underlying bazilfuse request.
 //
@@ -216,8 +120,8 @@ func (c *Connection) beginOp(
 	bfReq bazilfuse.Request) (ctx context.Context) {
 	reqID := bfReq.Hdr().ID
 
-	// Choose a parent context.
-	ctx = c.maybeTraceByPID(int(bfReq.Hdr().Pid))
+	// Start with the parent context.
+	ctx = c.parentCtx
 
 	// Set up a cancellation function.
 	//

debug.go

-// Copyright 2015 Google Inc. All Rights Reserved.
-//
-// 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 fuse
-
-import (
-	"flag"
-	"io"
-	"io/ioutil"
-	"log"
-	"os"
-	"sync"
-)
-
-var fEnableDebug = flag.Bool(
-	"fuse.debug",
-	false,
-	"Write FUSE debugging messages to stderr.")
-
-var gDebugLogger *log.Logger
-var gDebugLoggerOnce sync.Once
-
-func initDebugDebugLogger() {
-	if !flag.Parsed() {
-		panic("initDebugDebugLogger called before flags available.")
-	}
-
-	var writer io.Writer = ioutil.Discard
-	if *fEnableDebug {
-		writer = os.Stderr
-	}
-
-	const flags = log.Ldate | log.Ltime | log.Lmicroseconds
-	gDebugLogger = log.New(writer, "", flags)
-}
-
-func getDebugLogger() *log.Logger {
-	gDebugLoggerOnce.Do(initDebugDebugLogger)
-	return gDebugLogger
-}

fuseops/ops.go

@@ -49,7 +49,7 @@ type Op interface {
 
 	// Log information tied to this operation, with semantics equivalent to
 	// log.Printf, except that the format is different and logging is suppressed
-	// if --fuse.debug is not set.
+	// if no debug logger was set when mounting.
 	Logf(format string, v ...interface{})
 }
 

fuseutil/file_system.go

@@ -15,20 +15,13 @@
 package fuseutil
 
 import (
-	"flag"
 	"io"
-	"math/rand"
 	"sync"
-	"time"
 
 	"github.com/jacobsa/fuse"
 	"github.com/jacobsa/fuse/fuseops"
 )
 
-var fRandomDelays = flag.Bool(
-	"fuseutil.random_delays", false,
-	"If set, randomly delay each op received, to help expose concurrency issues.")
-
 // An interface with a method for each op type in the fuseops package. This can
 // be used in conjunction with NewFileSystemServer to avoid writing a "dispatch
 // loop" that switches on op types, instead receiving typed method calls
@@ -115,13 +108,6 @@ func (s *fileSystemServer) ServeOps(c *fuse.Connection) {
 func (s *fileSystemServer) handleOp(op fuseops.Op) {
 	defer s.opsInFlight.Done()
 
-	// Delay if requested.
-	if *fRandomDelays {
-		const delayLimit = 100 * time.Microsecond
-		delay := time.Duration(rand.Int63n(int64(delayLimit)))
-		time.Sleep(delay)
-	}
-
 	// Dispatch to the appropriate method.
 	var err error
 	switch typed := op.(type) {

mounted_file_system.go

@@ -84,6 +84,10 @@ type MountConfig struct {
 	// logging is performed.
 	ErrorLogger *log.Logger
 
+	// A logger to use for logging debug information. If nil, no debug logging is
+	// performed.
+	DebugLogger *log.Logger
+
 	// OS X only.
 	//
 	// Normally on OS X we mount with the novncache option
@@ -189,7 +193,11 @@ func Mount(
 	dir string,
 	server Server,
 	config *MountConfig) (mfs *MountedFileSystem, err error) {
-	debugLogger := getDebugLogger()
+	// Arrange for a non-nil debug logger.
+	debugLogger := config.DebugLogger
+	if debugLogger == nil {
+		debugLogger = log.New(ioutil.Discard, "", 0)
+	}
 
 	// Initialize the struct.
 	mfs = &MountedFileSystem{

samples/in_process.go

@@ -18,6 +18,7 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"log"
 	"os"
 	"time"
 
@@ -59,7 +60,12 @@ type SampleTest struct {
 //
 // REQUIRES: t.Server has been set.
 func (t *SampleTest) SetUp(ti *ogletest.TestInfo) {
-	err := t.initialize(ti.Ctx, t.Server, &t.MountConfig)
+	cfg := t.MountConfig
+	if *fDebug {
+		cfg.DebugLogger = log.New(os.Stderr, "fuse: ", 0)
+	}
+
+	err := t.initialize(ti.Ctx, t.Server, &cfg)
 	if err != nil {
 		panic(err)
 	}

samples/mount_sample/mount.go

@@ -40,6 +40,7 @@ var fFlushError = flag.Int("flushfs.flush_error", 0, "")
 var fFsyncError = flag.Int("flushfs.fsync_error", 0, "")
 
 var fReadOnly = flag.Bool("read_only", false, "Mount in read-only mode.")
+var fDebug = flag.Bool("debug", false, "Enable debug logging.")
 
 func makeFlushFS() (server fuse.Server, err error) {
 	// Check the flags.
@@ -140,6 +141,10 @@ func main() {
 		ReadOnly: *fReadOnly,
 	}
 
+	if *fDebug {
+		cfg.DebugLogger = log.New(os.Stderr, "fuse: ", 0)
+	}
+
 	mfs, err := fuse.Mount(*fMountPoint, server, cfg)
 	if err != nil {
 		log.Fatalf("Mount: %v", err)

samples/subprocess.go

@@ -276,7 +276,7 @@ func (t *SubprocessTest) initialize(ctx context.Context) (err error) {
 	// Handle debug mode.
 	if *fDebug {
 		mountCmd.Stderr = os.Stderr
-		mountCmd.Args = append(mountCmd.Args, "--fuse.debug")
+		mountCmd.Args = append(mountCmd.Args, "--debug")
 	}
 
 	// Start the command.