Moved per-PID tracing to Connection.
This lets it happen before per-request cancellation, which otherwise causes all future ops to start cancelled after one finishes.geesefs-0-30-9
Aaron Jacobs
parent
a9b17361e8
commit
cb273d013a
100
connection.go
100
connection.go
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@ -15,18 +15,29 @@
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package fuse
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import (
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"flag"
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"fmt"
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"log"
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"path"
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"runtime"
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"sync"
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"time"
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"golang.org/x/net/context"
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"golang.org/x/sys/unix"
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"github.com/jacobsa/bazilfuse"
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"github.com/jacobsa/fuse/fuseops"
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"github.com/jacobsa/reqtrace"
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)
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var fTraceByPID = flag.Bool(
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"fuse.trace_by_pid",
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false,
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"Enable a hacky mode that uses reqtrace to group all ops from each "+
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"individual PID. Not a good idea to use in production; races, bugs, and "+
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"resource leaks likely lurk.")
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// A connection to the fuse kernel process.
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type Connection struct {
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logger *log.Logger
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@ -46,6 +57,11 @@ type Connection struct {
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//
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// GUARDED_BY(mu)
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cancelFuncs map[bazilfuse.RequestID]func()
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// A map from PID to a traced context for that PID.
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//
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// GUARDED_BY(mu)
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pidMap map[int]context.Context
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}
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// Responsibility for closing the wrapped connection is transferred to the
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@ -59,6 +75,7 @@ func newConnection(
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wrapped: wrapped,
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parentCtx: parentCtx,
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cancelFuncs: make(map[bazilfuse.RequestID]func()),
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pidMap: make(map[int]context.Context),
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}
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return
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@ -108,6 +125,85 @@ func (c *Connection) recordCancelFunc(
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c.cancelFuncs[reqID] = f
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}
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// Wait until the process completes, then close off the trace and remove the
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// context from the map.
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//
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// LOCKS_EXCLUDED(c.mu)
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func (c *Connection) reportWhenPIDGone(
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pid int,
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ctx context.Context,
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report reqtrace.ReportFunc) {
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// HACK(jacobsa): Poll until the process no longer exists.
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const pollPeriod = 50 * time.Millisecond
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for {
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// The man page for kill(2) says that if the signal is zero, then "no
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// signal is sent, but error checking is still performed; this can be used
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// to check for the existence of a process ID".
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err := unix.Kill(pid, 0)
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// ESRCH means the process is gone.
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if err == unix.ESRCH {
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break
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}
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// If we receive EPERM, we're not going to be able to do what we want. We
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// don't really have any choice but to print info and leak.
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if err == unix.EPERM {
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log.Printf("Failed to kill(2) PID %v; no permissions. Leaking trace.", pid)
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return
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}
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// Otherwise, panic.
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if err != nil {
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panic(fmt.Errorf("Kill(%v): %v", pid, err))
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}
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time.Sleep(pollPeriod)
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}
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// Finish up.
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report(nil)
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c.mu.Lock()
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delete(c.pidMap, pid)
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c.mu.Unlock()
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}
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// Set up a hacky per-PID trace context, if enabled. Either way, return a
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// context from which an operation should inherit.
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//
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// See notes on fTraceByPID.
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//
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// LOCKS_EXCLUDED(c.mu)
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func (c *Connection) maybeTraceByPID(
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pid int) (ctx context.Context) {
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ctx = c.parentCtx
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// Is there anything to do?
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if !reqtrace.Enabled() || !*fTraceByPID {
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return
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}
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c.mu.Lock()
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defer c.mu.Unlock()
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// Do we already have a traced context for this PID?
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if existing, ok := c.pidMap[pid]; ok {
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ctx = existing
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return
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}
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// Set up a new one and stick it in the map.
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var report reqtrace.ReportFunc
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ctx, report = reqtrace.Trace(ctx, fmt.Sprintf("Requests from PID %v", pid))
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c.pidMap[pid] = ctx
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// Ensure we close the trace and remove it from the map eventually.
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go c.reportWhenPIDGone(pid, ctx, report)
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return
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}
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// Set up state for an op that is about to be returned to the user, given its
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// underlying bazilfuse request.
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//
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@ -121,6 +217,9 @@ func (c *Connection) beginOp(
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// Note that the op is in flight.
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c.opsInFlight.Add(1)
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// Choose a parent context.
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ctx = c.maybeTraceByPID(int(bfReq.Hdr().Pid))
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// Set up a cancellation function.
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//
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// Special case: On Darwin, osxfuse appears to aggressively reuse "unique"
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@ -129,7 +228,6 @@ func (c *Connection) beginOp(
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// for reuse. For these, we should not record any state keyed on their ID.
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//
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// Cf. https://github.com/osxfuse/osxfuse/issues/208
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ctx = c.parentCtx
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if _, ok := bfReq.(*bazilfuse.ForgetRequest); !ok {
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var cancel func()
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ctx, cancel = context.WithCancel(ctx)
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@ -15,27 +15,15 @@
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package fuseops
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import (
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"flag"
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"fmt"
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"log"
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"reflect"
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"strings"
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"sync"
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"time"
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"github.com/jacobsa/bazilfuse"
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"github.com/jacobsa/reqtrace"
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"golang.org/x/net/context"
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"golang.org/x/sys/unix"
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)
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var fTraceByPID = flag.Bool(
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"fuse.trace_by_pid",
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false,
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"Enable a hacky mode that uses reqtrace to group all ops from each "+
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"individual PID. Not a good idea to use in production; races, bugs, and "+
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"resource leaks likely lurk.")
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// An interface that all ops inside which commonOp is embedded must
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// implement.
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type internalOp interface {
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@ -67,84 +55,6 @@ type commonOp struct {
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finished func(error)
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}
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var gPIDMapMu sync.Mutex
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// A map from PID to a traced context for that PID.
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//
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// GUARDED_BY(gPIDMapMu)
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var gPIDMap = make(map[int]context.Context)
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// Wait until the process completes, then close off the trace and remove the
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// context from the map.
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func reportWhenPIDGone(
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pid int,
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ctx context.Context,
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report reqtrace.ReportFunc) {
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// HACK(jacobsa): Poll until the process no longer exists.
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const pollPeriod = 50 * time.Millisecond
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for {
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// The man page for kill(2) says that if the signal is zero, then "no
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// signal is sent, but error checking is still performed; this can be used
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// to check for the existence of a process ID".
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err := unix.Kill(pid, 0)
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// ESRCH means the process is gone.
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if err == unix.ESRCH {
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break
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}
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// If we receive EPERM, we're not going to be able to do what we want. We
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// don't really have any choice but to print info and leak.
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if err == unix.EPERM {
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log.Printf("Failed to kill(2) PID %v; no permissions. Leaking trace.", pid)
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return
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}
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// Otherwise, panic.
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if err != nil {
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panic(fmt.Errorf("Kill(%v): %v", pid, err))
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}
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time.Sleep(pollPeriod)
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}
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// Finish up.
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report(nil)
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gPIDMapMu.Lock()
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delete(gPIDMap, pid)
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gPIDMapMu.Unlock()
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}
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func (o *commonOp) maybeTraceByPID(
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in context.Context,
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pid int) (out context.Context) {
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// Is there anything to do?
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if !reqtrace.Enabled() || !*fTraceByPID {
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out = in
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return
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}
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gPIDMapMu.Lock()
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defer gPIDMapMu.Unlock()
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// Do we already have a traced context for this PID?
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if existing, ok := gPIDMap[pid]; ok {
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out = existing
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return
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}
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// Set up a new one and stick it in the map.
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var report reqtrace.ReportFunc
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out, report = reqtrace.Trace(in, fmt.Sprintf("Requests from PID %v", pid))
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gPIDMap[pid] = out
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// Ensure we close the trace and remove it from the map eventually.
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go reportWhenPIDGone(pid, out, report)
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return
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}
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func (o *commonOp) ShortDesc() (desc string) {
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opName := reflect.TypeOf(o.op).String()
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@ -175,9 +85,6 @@ func (o *commonOp) init(
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o.log = log
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o.finished = finished
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// Set up a context that reflects per-PID tracing if appropriate.
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o.ctx = o.maybeTraceByPID(o.ctx, int(bazilReq.Hdr().Pid))
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// Set up a trace span for this op.
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var reportForTrace reqtrace.ReportFunc
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o.ctx, reportForTrace = reqtrace.StartSpan(o.ctx, o.op.ShortDesc())
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