1. docker
  2. Commit f4b08c7f5eed2eece239086f260eee9e736ee227
Browse code

Windows: Win32 event for sigusr1 linux equivalence

Signed-off-by: John Howard <jhoward@microsoft.com>

John Howard authored on 2015/07/07 10:58:53
Showing 6 changed files
daemon/daemon.go
History View file @ f4b08c7
... ... 
@@ -568,8 +568,9 @@ func NewDaemon(config *Config, registryService *registry.Service) (daemon *Daemo
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 		return nil, err
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 	}
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-	// set up SIGUSR1 handler to dump Go routine stacks
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-	setupSigusr1Trap()
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+	// set up SIGUSR1 handler on Unix-like systems, or a Win32 global event
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+	// on Windows to dump Go routine stacks
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+	setupDumpStackTrap()
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 	// get the canonical path to the Docker root directory
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 	var realRoot string
daemon/debugtrap.go
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deleted file mode 100644
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@@ -1,21 +0,0 @@
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-// +build !windows
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-
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-package daemon
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-
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-import (
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-	"os"
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-	"os/signal"
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-	"syscall"
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-
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-	psignal "github.com/docker/docker/pkg/signal"
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-)
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-
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-func setupSigusr1Trap() {
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-	c := make(chan os.Signal, 1)
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-	signal.Notify(c, syscall.SIGUSR1)
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-	go func() {
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-		for range c {
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-			psignal.DumpStacks()
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-		}
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-	}()
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-}
daemon/debugtrap_unix.go
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@@ -0,0 +1,21 @@
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+// +build !windows
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+
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+package daemon
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+
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+import (
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+	"os"
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+	"os/signal"
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+	"syscall"
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+
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+	psignal "github.com/docker/docker/pkg/signal"
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+)
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+
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+func setupDumpStackTrap() {
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+	c := make(chan os.Signal, 1)
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+	signal.Notify(c, syscall.SIGUSR1)
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+	go func() {
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+		for range c {
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+			psignal.DumpStacks()
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+		}
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+	}()
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+}
daemon/debugtrap_unsupported.go
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@@ -1,7 +1,7 @@
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-// +build !linux,!darwin,!freebsd
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+// +build !linux,!darwin,!freebsd,!windows
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 package daemon
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-func setupSigusr1Trap() {
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+func setupDumpStackTrap() {
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 	return
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 }
daemon/debugtrap_windows.go
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new file mode 100644
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@@ -0,0 +1,30 @@
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+package daemon
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+
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+import (
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+	"fmt"
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+	"os"
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+	"syscall"
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+
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+	"github.com/Sirupsen/logrus"
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+	psignal "github.com/docker/docker/pkg/signal"
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+	"github.com/docker/docker/pkg/system"
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+)
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+
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+func setupDumpStackTrap() {
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+	// Windows does not support signals like *nix systems. So instead of
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+	// trapping on SIGUSR1 to dump stacks, we wait on a Win32 event to be
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+	// signalled.
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+	go func() {
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+		sa := syscall.SecurityAttributes{
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+			Length: 0,
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+		}
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+		ev := "Global\\docker-daemon-" + fmt.Sprint(os.Getpid())
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+		if h, _ := system.CreateEvent(&sa, false, false, ev); h != 0 {
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+			logrus.Debugf("Stackdump - waiting signal at %s", ev)
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+			for {
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+				syscall.WaitForSingleObject(h, syscall.INFINITE)
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+				psignal.DumpStacks()
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+			}
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+		}
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+	}()
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+}
pkg/system/events_windows.go
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@@ -0,0 +1,83 @@
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+package system
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+
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+// This file implements syscalls for Win32 events which are not implemented
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+// in golang.
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+
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+import (
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+	"syscall"
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+	"unsafe"
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+)
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+
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+const (
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+	EVENT_ALL_ACCESS    = 0x1F0003
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+	EVENT_MODIFY_STATUS = 0x0002
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+)
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+
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+var (
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+	procCreateEvent = modkernel32.NewProc("CreateEventW")
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+	procOpenEvent   = modkernel32.NewProc("OpenEventW")
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+	procSetEvent    = modkernel32.NewProc("SetEvent")
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+	procResetEvent  = modkernel32.NewProc("ResetEvent")
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+	procPulseEvent  = modkernel32.NewProc("PulseEvent")
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+)
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+
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+func CreateEvent(eventAttributes *syscall.SecurityAttributes, manualReset bool, initialState bool, name string) (handle syscall.Handle, err error) {
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+	namep, _ := syscall.UTF16PtrFromString(name)
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+	var _p1 uint32 = 0
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+	if manualReset {
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+		_p1 = 1
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+	}
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+	var _p2 uint32 = 0
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+	if initialState {
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+		_p2 = 1
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+	}
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+	r0, _, e1 := procCreateEvent.Call(uintptr(unsafe.Pointer(eventAttributes)), uintptr(_p1), uintptr(_p2), uintptr(unsafe.Pointer(namep)))
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+	use(unsafe.Pointer(namep))
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+	handle = syscall.Handle(r0)
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+	if handle == syscall.InvalidHandle {
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+		err = e1
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+	}
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+	return
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+}
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+
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+func OpenEvent(desiredAccess uint32, inheritHandle bool, name string) (handle syscall.Handle, err error) {
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+	namep, _ := syscall.UTF16PtrFromString(name)
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+	var _p1 uint32 = 0
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+	if inheritHandle {
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+		_p1 = 1
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+	}
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+	r0, _, e1 := procOpenEvent.Call(uintptr(desiredAccess), uintptr(_p1), uintptr(unsafe.Pointer(namep)))
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+	use(unsafe.Pointer(namep))
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+	handle = syscall.Handle(r0)
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+	if handle == syscall.InvalidHandle {
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+		err = e1
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+	}
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+	return
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+}
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+
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+func SetEvent(handle syscall.Handle) (err error) {
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+	return setResetPulse(handle, procSetEvent)
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+}
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+
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+func ResetEvent(handle syscall.Handle) (err error) {
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+	return setResetPulse(handle, procResetEvent)
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+}
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+
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+func PulseEvent(handle syscall.Handle) (err error) {
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+	return setResetPulse(handle, procPulseEvent)
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+}
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+
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+func setResetPulse(handle syscall.Handle, proc *syscall.LazyProc) (err error) {
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+	r0, _, _ := proc.Call(uintptr(handle))
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+	if r0 != 0 {
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+		err = syscall.Errno(r0)
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+	}
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+	return
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+}
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+
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+var temp unsafe.Pointer
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+
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+// use ensures a variable is kept alive without the GC freeing while still needed
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+func use(p unsafe.Pointer) {
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+	temp = p
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+}