Use thread-local storage to block event_queue recursion.

src/common/compat_pthreads.c

@@ -275,6 +275,33 @@ tor_cond_signal_all(tor_cond_t *cond)
   pthread_cond_broadcast(&cond->cond);
 }
 
+int
+tor_threadlocal_init(tor_threadlocal_t *threadlocal)
+{
+  int err = pthread_key_create(&threadlocal->key, NULL);
+  return err ? -1 : 0;
+}
+
+void
+tor_threadlocal_destroy(tor_threadlocal_t *threadlocal)
+{
+  pthread_key_delete(threadlocal->key);
+  memset(threadlocal, 0, sizeof(tor_threadlocal_t));
+}
+
+void *
+tor_threadlocal_get(tor_threadlocal_t *threadlocal)
+{
+  return pthread_getspecific(threadlocal->key);
+}
+
+void
+tor_threadlocal_set(tor_threadlocal_t *threadlocal, void *value)
+{
+  int err = pthread_setspecific(threadlocal->key, value);
+  tor_assert(err == 0);
+}
+
 /** Set up common structures for use by threading. */
 void
 tor_threads_init(void)

src/common/compat_threads.h

@@ -111,5 +111,18 @@ typedef struct alert_sockets_s {
 int alert_sockets_create(alert_sockets_t *socks_out, uint32_t flags);
 void alert_sockets_close(alert_sockets_t *socks);
 
+typedef struct tor_threadlocal_s {
+#ifdef _WIN32
+  DWORD index;
+#else
+  pthread_key_t key;
+#endif
+} tor_threadlocal_t;
+
+int tor_threadlocal_init(tor_threadlocal_t *threadlocal);
+void tor_threadlocal_destroy(tor_threadlocal_t *threadlocal);
+void *tor_threadlocal_get(tor_threadlocal_t *threadlocal);
+void tor_threadlocal_set(tor_threadlocal_t *threadlocal, void *value);
+
 #endif
 

src/common/compat_winthreads.c

@@ -122,6 +122,33 @@ tor_cond_signal_all(tor_cond_t *cond)
   tor_cond_signal_impl(cond, 1);
 }
 
+int
+tor_threadlocal_init(tor_threadlocal_t *threadlocal)
+{
+  threadlocal->index = TlsAlloc();
+  return (threadlocal->index == TLS_OUT_OF_INDEXES) ? -1 : 0;
+}
+
+void
+tor_threadlocal_destroy(tor_threadlocal_t *threadlocal)
+{
+  TlsFree(threadlocal->index);
+  memset(threadlocal, 0, sizeof(tor_threadlocal_t));
+}
+
+void *
+tor_threadlocal_get(tor_threadlocal_t *threadlocal)
+{
+  return TlsGetValue(threadlocal->index);
+}
+
+void
+tor_threadlocal_set(tor_threadlocal_t *threadlocal, void *value)
+{
+  BOOL ok = TlsSetValue(threadlocal->index, value);
+  tor_assert(ok);
+}
+
 int
 tor_cond_wait(tor_cond_t *cond, tor_mutex_t *lock_, const struct timeval *tv)
 {