[tor-commits] [tor/master] Implement WIN32 tor_cond_wait using condition variables #30187
ahf at torproject.org
ahf at torproject.org
Mon Nov 9 14:13:50 UTC 2020
commit f3b9be4422a08b6066bdb93874a5023e7c11ce9e
Author: Daniel Pinto <danielpinto52 at gmail.com>
Date: Sat Oct 31 18:33:33 2020 +0000
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.
---
changes/bug30187 | 5 ++
configure.ac | 8 +--
src/lib/thread/compat_winthreads.c | 124 +++++++++++--------------------------
src/lib/thread/threads.h | 7 +--
4 files changed, 47 insertions(+), 97 deletions(-)
diff --git a/changes/bug30187 b/changes/bug30187
new file mode 100644
index 0000000000..2a3358d6be
--- /dev/null
+++ b/changes/bug30187
@@ -0,0 +1,5 @@
+ 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.
diff --git a/configure.ac b/configure.ac
index 2ee0a5721f..a7ecd1d0fe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -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 */
diff --git a/src/lib/thread/compat_winthreads.c b/src/lib/thread/compat_winthreads.c
index 2ca5620d23..fcc9c0279b 100644
--- a/src/lib/thread/compat_winthreads.c
+++ b/src/lib/thread/compat_winthreads.c
@@ -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);
+ DWORD ms = INFINITE;
+ if (tv) {
+ ms = tv->tv_sec*1000 + (tv->tv_usec+999)/1000;
+ }
- return result;
+ 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
diff --git a/src/lib/thread/threads.h b/src/lib/thread/threads.h
index fcc0c23a87..ead4dc3874 100644
--- a/src/lib/thread/threads.h
+++ b/src/lib/thread/threads.h
@@ -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) || ... */
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