Commit f3b9be44 authored by Jigsaw52's avatar Jigsaw52
Browse files

Implement WIN32 tor_cond_wait using condition variables #30187 

Fix bug where running a relay on Windows would use 100% CPU
after some time. Makes Windows >= Vista the required Windows
version to build and run tor.
parent 6e25c49f

changes/bug30187

0 → 100644
+5 −0
Original line number Diff line number Diff line 
  o Major bugfixes (relay, windows):

    - Fix bug where running a relay on Windows would use 100%

      CPU after some time. Makes Windows >= Vista the required

      Windows version to build and run tor. Fixes bug 30187;

      bugfix on 0.4.5.1-alpha. Patch by Daniel Pinto.

configure.ac

+4 −4
Original line number Diff line number Diff line
@@ -560,14 +560,14 @@ fi 


AH_BOTTOM([

#ifdef _WIN32

/* Defined to access windows functions and definitions for >=WinXP */

/* Defined to access windows functions and definitions for >=WinVista */

# ifndef WINVER

#  define WINVER 0x0501

#  define WINVER 0x0600

# endif



/* Defined to access _other_ windows functions and definitions for >=WinXP */

/* Defined to access _other_ windows functions and definitions for >=WinVista */

# ifndef _WIN32_WINNT

#  define _WIN32_WINNT 0x0501

#  define _WIN32_WINNT 0x0600

# endif



/* Defined to avoid including some windows headers as part of Windows.h */

src/lib/thread/compat_winthreads.c

+37 −87
Original line number Diff line number Diff line
@@ -10,18 +10,32 @@ 
 * functions.

 */



#include "orconfig.h"



#ifdef _WIN32

/* For condition variable support */

#ifndef WINVER

#error "orconfig.h didn't define WINVER"

#endif

#ifndef _WIN32_WINNT

#error "orconfig.h didn't define _WIN32_WINNT"

#endif

#if WINVER < 0x0600

#error "winver too low"

#endif

#if _WIN32_WINNT < 0x0600

#error "winver too low"

#endif



#include <windows.h>

#include <process.h>

#include <time.h>



#include "lib/thread/threads.h"

#include "lib/log/log.h"

#include "lib/log/util_bug.h"

#include "lib/log/win32err.h"



/* This value is more or less total cargo-cult */

#define SPIN_COUNT 2000



/** Minimalist interface to run a void function in the background.  On

 * Unix calls fork, on win32 calls beginthread.  Returns -1 on failure.

 * func should not return, but rather should call spawn_exit.
@@ -64,45 +78,24 @@ tor_get_thread_id(void) 
int

tor_cond_init(tor_cond_t *cond)

{

  memset(cond, 0, sizeof(tor_cond_t));

  if (InitializeCriticalSectionAndSpinCount(&cond->lock, SPIN_COUNT)==0) {

    return -1;

  }

  if ((cond->event = CreateEvent(NULL,TRUE,FALSE,NULL)) == NULL) {

    DeleteCriticalSection(&cond->lock);

    return -1;

  }

  cond->n_waiting = cond->n_to_wake = cond->generation = 0;

  InitializeConditionVariable(&cond->cond);

  return 0;

}

void

tor_cond_uninit(tor_cond_t *cond)

{

  DeleteCriticalSection(&cond->lock);

  CloseHandle(cond->event);

  (void) cond;

}



static void

tor_cond_signal_impl(tor_cond_t *cond, int broadcast)

{

  EnterCriticalSection(&cond->lock);

  if (broadcast)

    cond->n_to_wake = cond->n_waiting;

  else

    ++cond->n_to_wake;

  cond->generation++;

  SetEvent(cond->event);

  LeaveCriticalSection(&cond->lock);

}

void

tor_cond_signal_one(tor_cond_t *cond)

{

  tor_cond_signal_impl(cond, 0);

  WakeConditionVariable(&cond->cond);

}

void

tor_cond_signal_all(tor_cond_t *cond)

{

  tor_cond_signal_impl(cond, 1);

  WakeAllConditionVariable(&cond->cond);

}



int
@@ -152,66 +145,23 @@ int 
tor_cond_wait(tor_cond_t *cond, tor_mutex_t *lock_, const struct timeval *tv)

{

  CRITICAL_SECTION *lock = &lock_->mutex;

  int generation_at_start;

  int waiting = 1;

  int result = -1;

  DWORD ms = INFINITE, ms_orig = INFINITE, startTime, endTime;

  if (tv)

    ms_orig = ms = tv->tv_sec*1000 + (tv->tv_usec+999)/1000;



  EnterCriticalSection(&cond->lock);

  ++cond->n_waiting;

  generation_at_start = cond->generation;

  LeaveCriticalSection(&cond->lock);



  LeaveCriticalSection(lock);



  startTime = GetTickCount();

  do {

    DWORD res;

    res = WaitForSingleObject(cond->event, ms);

    EnterCriticalSection(&cond->lock);

    if (cond->n_to_wake &&

        cond->generation != generation_at_start) {

      --cond->n_to_wake;

      --cond->n_waiting;

      result = 0;

      waiting = 0;

      goto out;

    } else if (res != WAIT_OBJECT_0) {

      result = (res==WAIT_TIMEOUT) ? 1 : -1;

      --cond->n_waiting;

      waiting = 0;

      goto out;

    } else if (ms != INFINITE) {

      endTime = GetTickCount();

      if (startTime + ms_orig <= endTime) {

        result = 1; /* Timeout */

        --cond->n_waiting;

        waiting = 0;

        goto out;

      } else {

        ms = startTime + ms_orig - endTime;

      }

    }

    /* If we make it here, we are still waiting. */

    if (cond->n_to_wake == 0) {

      /* There is nobody else who should wake up; reset

       * the event. */

      ResetEvent(cond->event);

    }

  out:

    LeaveCriticalSection(&cond->lock);

  } while (waiting);



  EnterCriticalSection(lock);



  EnterCriticalSection(&cond->lock);

  if (!cond->n_waiting)

    ResetEvent(cond->event);

  LeaveCriticalSection(&cond->lock);



  return result;

  DWORD ms = INFINITE;

  if (tv) {

    ms = tv->tv_sec*1000 + (tv->tv_usec+999)/1000;

  }



  BOOL ok = SleepConditionVariableCS(&cond->cond, lock, ms);

  if (!ok) {

    DWORD err = GetLastError();

    if (err == ERROR_TIMEOUT) {

      return 1;

    }

    char *msg = format_win32_error(err);

    log_err(LD_GENERAL, "Error waiting for condition variable: %s", msg);

    tor_free(msg);

    return -1;

  }

  return 0;

}



void

src/lib/thread/threads.h

+1 −6
Original line number Diff line number Diff line
@@ -42,12 +42,7 @@ typedef struct tor_cond_t { 
#ifdef USE_PTHREADS

  pthread_cond_t cond;

#elif defined(USE_WIN32_THREADS)

  HANDLE event;



  CRITICAL_SECTION lock;

  int n_waiting;

  int n_to_wake;

  int generation;

  CONDITION_VARIABLE cond;

#else

#error no known condition implementation.

#endif /* defined(USE_PTHREADS) || ... */