asyn-thrdd: remove condition variable

Add a flag `thrd_don` to assess if the resolving thread has finished and
only destroy the context when *both* ref_count reaches 0 and thrd_done
is true.

Closes #18345

diff --git a/lib/asyn-thrdd.c b/lib/asyn-thrdd.c
index dbc13d072212910de03d2c780e07e6a181dcd665..1ff2d949d27c90a6a78b48e0faca2d0f1fe7bde3 100644 (file)
--- a/lib/asyn-thrdd.c
+++ b/lib/asyn-thrdd.c
@@ -128,9 +128,12 @@ static void addr_ctx_unlink(struct async_thrdd_addr_ctx **paddr_ctx,
     return;
 
   Curl_mutex_acquire(&addr_ctx->mutx);
+  if(!data)  /* called by resolving thread */
+    addr_ctx->thrd_done = TRUE;
+
   DEBUGASSERT(addr_ctx->ref_count);
   --addr_ctx->ref_count;
-  destroy = !addr_ctx->ref_count; /* was the last one */
+  destroy = (!addr_ctx->ref_count && addr_ctx->thrd_done);
 
 #ifndef CURL_DISABLE_SOCKETPAIR
   if(!destroy) {
@@ -168,9 +171,6 @@ static void addr_ctx_unlink(struct async_thrdd_addr_ctx **paddr_ctx,
   Curl_mutex_release(&addr_ctx->mutx);
 
   if(destroy) {
-#ifdef USE_CURL_COND_T
-    Curl_cond_destroy(&addr_ctx->cond);
-#endif
     Curl_mutex_destroy(&addr_ctx->mutx);
     free(addr_ctx->hostname);
     if(addr_ctx->res)
@@ -206,9 +206,6 @@ addr_ctx_create(struct Curl_easy *data,
 #endif
 
   Curl_mutex_init(&addr_ctx->mutx);
-#ifdef USE_CURL_COND_T
-  Curl_cond_init(&addr_ctx->cond);
-#endif
 
 #ifndef CURL_DISABLE_SOCKETPAIR
   /* create socket pair or pipe */
@@ -245,13 +242,8 @@ static bool asyn_thrd_start(struct async_thrdd_addr_ctx *addr_ctx)
 {
   Curl_thread_disable_cancel();
   Curl_mutex_acquire(&addr_ctx->mutx);
-  DEBUGASSERT(addr_ctx->ref_count);
   ++addr_ctx->ref_count;
-#ifdef USE_CURL_COND_T
-  Curl_cond_signal(&addr_ctx->cond);
-#endif
   Curl_mutex_release(&addr_ctx->mutx);
-
   return TRUE;
 }
 
@@ -376,10 +368,10 @@ static void async_thrdd_destroy(struct Curl_easy *data)
 #endif
 
   if(thrdd->addr && (thrdd->addr->thread_hnd != curl_thread_t_null)) {
-    bool done = TRUE;
+    bool done;
 
     Curl_mutex_acquire(&addr->mutx);
-    done = (addr->ref_count <= 1);
+    done = addr->thrd_done;
     Curl_mutex_release(&addr->mutx);
     if(done) {
       Curl_thread_join(&addr->thread_hnd);
@@ -498,18 +490,12 @@ static bool async_thrdd_init(struct Curl_easy *data,
 
   if(addr_ctx->thread_hnd == curl_thread_t_null) {
     /* The thread never started */
+    addr_ctx->thrd_done = TRUE;
     Curl_mutex_release(&addr_ctx->mutx);
     err = errno;
     goto err_exit;
   }
-  else {
-#ifdef USE_CURL_COND_T
-    /* need to handshake with thread for participation in ref counting */
-    Curl_cond_wait(&addr_ctx->cond, &addr_ctx->mutx);
-    DEBUGASSERT(addr_ctx->ref_count >= 1);
-#endif
-    Curl_mutex_release(&addr_ctx->mutx);
-  }
+  Curl_mutex_release(&addr_ctx->mutx);
 
 #ifdef USE_HTTPSRR_ARES
   if(async_rr_start(data))
@@ -537,7 +523,7 @@ static void async_thrdd_shutdown(struct Curl_easy *data)
     return;
 
   Curl_mutex_acquire(&addr_ctx->mutx);
-  done = (addr_ctx->ref_count <= 1);
+  done = addr_ctx->thrd_done;
   /* We are no longer interested in wakeups */
   if(addr_ctx->sock_pair[1] != CURL_SOCKET_BAD) {
     wakeup_close(addr_ctx->sock_pair[1]);
@@ -571,6 +557,7 @@ static CURLcode asyn_thrdd_await(struct Curl_easy *data,
 #ifdef DEBUGBUILD
       Curl_mutex_acquire(&addr_ctx->mutx);
       DEBUGASSERT(addr_ctx->ref_count == 1);
+      DEBUGASSERT(addr_ctx->thrd_done);
       Curl_mutex_release(&addr_ctx->mutx);
 #endif
       if(entry)
@@ -660,7 +647,7 @@ CURLcode Curl_async_is_resolved(struct Curl_easy *data,
     return CURLE_FAILED_INIT;
 
   Curl_mutex_acquire(&thrdd->addr->mutx);
-  done = (thrdd->addr->ref_count == 1);
+  done = thrdd->addr->thrd_done;
   Curl_mutex_release(&thrdd->addr->mutx);
 
   if(done) {

diff --git a/lib/asyn.h b/lib/asyn.h
index 5e56532bf09323c0bdb5344368cd5b577838d07e..8408d9edf34c6c2879a14306cecbb87829ba9137 100644 (file)
--- a/lib/asyn.h
+++ b/lib/asyn.h
@@ -180,9 +180,6 @@ struct async_thrdd_addr_ctx {
   char *hostname;        /* hostname to resolve, Curl_async.hostname
                             duplicate */
   curl_mutex_t mutx;
-#ifdef USE_CURL_COND_T
-  curl_cond_t  cond;
-#endif
 #ifndef CURL_DISABLE_SOCKETPAIR
   curl_socket_t sock_pair[2]; /* eventfd/pipes/socket pair */
 #endif
@@ -196,6 +193,7 @@ struct async_thrdd_addr_ctx {
   int port;
   int sock_error;
   int ref_count;
+  BIT(thrd_done);
 };
 
 /* Context for threaded resolver */

diff --git a/lib/curl_threads.c b/lib/curl_threads.c
index fe41c8bab5028696b7827e9a2a2375fb7a30e063..2750f5ad9f786c3b5f94a7f8a124de2dd71c60b1 100644 (file)
--- a/lib/curl_threads.c
+++ b/lib/curl_threads.c
@@ -36,7 +36,7 @@
 
 #include "curl_threads.h"
 #include "curl_memory.h"
-/* The last #include file should be: */
+/* The last #include FILE should be: */
 #include "memdebug.h"
 
 #ifdef USE_THREADS_POSIX

diff --git a/lib/curl_threads.h b/lib/curl_threads.h
index ea25acf750611c9f9322d0e00cd03c5157b0b0b9..115277c00eaa72c9bac018eebf81ce8e2316ef29 100644 (file)
--- a/lib/curl_threads.h
+++ b/lib/curl_threads.h
@@ -34,12 +34,6 @@
 #  define Curl_mutex_acquire(m)  pthread_mutex_lock(m)
 #  define Curl_mutex_release(m)  pthread_mutex_unlock(m)
 #  define Curl_mutex_destroy(m)  pthread_mutex_destroy(m)
-#  define USE_CURL_COND_T
-#  define curl_cond_t            pthread_cond_t
-#  define Curl_cond_init(c)      pthread_cond_init(c, NULL)
-#  define Curl_cond_destroy(c)   pthread_cond_destroy(c)
-#  define Curl_cond_wait(c, m)   pthread_cond_wait(c, m)
-#  define Curl_cond_signal(c)    pthread_cond_signal(c)
 #elif defined(USE_THREADS_WIN32)
 #  define CURL_STDCALL           __stdcall
 #  define curl_mutex_t           CRITICAL_SECTION
@@ -53,14 +47,6 @@
 #  define Curl_mutex_acquire(m)  EnterCriticalSection(m)
 #  define Curl_mutex_release(m)  LeaveCriticalSection(m)
 #  define Curl_mutex_destroy(m)  DeleteCriticalSection(m)
-#  if defined(_WIN32_WINNT) && (_WIN32_WINNT >= _WIN32_WINNT_VISTA)
-#  define USE_CURL_COND_T
-#  define curl_cond_t            CONDITION_VARIABLE
-#  define Curl_cond_init(c)      InitializeConditionVariable(c)
-#  define Curl_cond_destroy(c)   (void)(c)
-#  define Curl_cond_wait(c, m)   SleepConditionVariableCS(c, m, INFINITE)
-#  define Curl_cond_signal(c)    WakeConditionVariable(c)
-#  endif
 #else
 #  define CURL_STDCALL
 #endif