From eebff5df6a52c786322c3a8d7d2b21e73c70a98e Mon Sep 17 00:00:00 2001
From: Vitor Santos Costa <vsc@dcc.fc.up.pt>
Date: Fri, 23 Jul 2010 12:07:33 +0100
Subject: [PATCH] fixes to YAP C-thread interface.

---
 C/init.c                  |  3 +++
 C/threads.c               | 17 +++++++++++++++--
 H/Yap.h                   |  5 ++++-
 library/yap2swi/yap2swi.c |  5 +++--
 packages/jpl              |  2 +-
 5 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/C/init.c b/C/init.c
index 8b6237043..2874b369b 100755
--- a/C/init.c
+++ b/C/init.c
@@ -88,6 +88,8 @@ struct restore_info rinfo[MAX_THREADS];
 
 struct thread_globs Yap_thread_gl[MAX_THREADS];
 
+pthread_t Yap_master_thread;
+
 #else
 
 struct restore_info rinfo;
@@ -1246,6 +1248,7 @@ Yap_InitWorkspace(UInt Heap, UInt Stack, UInt Trail, UInt Atts, UInt max_table_s
 #ifdef THREADS
   pthread_key_create(&Yap_yaamregs_key, NULL);
   pthread_setspecific(Yap_yaamregs_key, (const void *)&Yap_standard_regs);
+  Yap_master_thread = pthread_self();
 #else
   /* In this case we need to initialise the abstract registers */
   Yap_regp = &Yap_standard_regs;
diff --git a/C/threads.c b/C/threads.c
index 917f9beaa..e1134b6a5 100755
--- a/C/threads.c
+++ b/C/threads.c
@@ -368,8 +368,13 @@ CELL
 Yap_thread_create_engine(thread_attr *ops)
 {
   thread_attr opsv;
-  Term t = TermNil;
   int new_id = allocate_new_tid();
+  Term t = TermNil;
+
+  /* 
+     ok, this creates a problem, because we are initializing an engine from some "empty" thread. 
+     We need first to foool the thread into believing it is the main thread
+  */
   if (new_id == -1) {
     /* YAP ERROR */
     return FALSE;
@@ -381,13 +386,21 @@ Yap_thread_create_engine(thread_attr *ops)
     ops->sysize = 0;
     ops->egoal = t;
   }
+  if (pthread_self() != Yap_master_thread) {
+    pthread_setspecific(Yap_yaamregs_key, (const void *)&Yap_standard_regs);
+    /* we are worker_id 0 for now, lock master thread so that no one messes with us */ 
+    pthread_mutex_lock(&(FOREIGN_ThreadHandle(0).tlock));
+  }
   if (!init_thread_engine(new_id, ops->ssize, ops->tsize, ops->sysize, &t, &t, &(ops->egoal)))
     return FALSE;
   FOREIGN_ThreadHandle(new_id).id = new_id;
   FOREIGN_ThreadHandle(new_id).pthread_handle = pthread_self();
   FOREIGN_ThreadHandle(new_id).ref_count = 0;
   setup_engine(new_id);
-  return TRUE;
+  if (pthread_self() != Yap_master_thread) {
+    pthread_mutex_unlock(&(FOREIGN_ThreadHandle(0).tlock));
+  }
+  return new_id;
 }
 
 Int
diff --git a/H/Yap.h b/H/Yap.h
index 64cb0e978..4a0abc50b 100755
--- a/H/Yap.h
+++ b/H/Yap.h
@@ -773,7 +773,6 @@ typedef struct thread_globs
 
 extern struct thread_globs Yap_thread_gl[MAX_THREADS];
 
-
 #define    Yap_LocalBase  Yap_thread_gl[worker_id].local_base
 #define    Yap_GlobalBase Yap_thread_gl[worker_id].global_base
 #define    Yap_TrailBase  Yap_thread_gl[worker_id].trail_base
@@ -784,6 +783,10 @@ extern struct thread_globs Yap_thread_gl[MAX_THREADS];
 #define    Yap_Error_Size   Yap_thread_gl[worker_id].error_size
 #define    Yap_ErrorSay    Yap_thread_gl[worker_id].error_say
 #define    Yap_RestartEnv    Yap_thread_gl[worker_id].restart_env
+
+/* This is the guy who actually started the system, and who has the correct registers */
+extern pthread_t Yap_master_thread;
+
 #else
 extern ADDR Yap_HeapBase,
   Yap_LocalBase, Yap_GlobalBase, Yap_TrailBase, Yap_TrailTop;
diff --git a/library/yap2swi/yap2swi.c b/library/yap2swi/yap2swi.c
index 794040026..47448cc2d 100755
--- a/library/yap2swi/yap2swi.c
+++ b/library/yap2swi/yap2swi.c
@@ -2784,7 +2784,6 @@ X_API int PL_thread_self(void)
 X_API int PL_thread_attach_engine(const PL_thread_attr_t *attr)
 {
   int wid = YAP_ThreadSelf();
-  fprintf(stderr,"attaching new engine %p\n", attr);
   
   if (wid < 0) {
     /* we do not have an engine */
@@ -2861,7 +2860,9 @@ X_API int
 PL_set_engine(PL_engine_t engine, PL_engine_t *old)
 {
   YAP_Int cwid = YAP_ThreadSelf();
-  if (*old) *old = (PL_engine_t)cwid;
+  if (old) {
+    if (*old) *old = (PL_engine_t)cwid;
+  }
   if (engine == PL_ENGINE_CURRENT)
     return PL_ENGINE_SET;
   if (engine < 0) /* should really check if engine does not exist */
diff --git a/packages/jpl b/packages/jpl
index daedb3738..7c9456b5c 160000
--- a/packages/jpl
+++ b/packages/jpl
@@ -1 +1 @@
-Subproject commit daedb37386cd9cdebd1473eed60d9bf240379d81
+Subproject commit 7c9456b5c9c60ab227674f7653dc226e13973484