From: Arnaud Giersch <arnaud.giersch@univ-fcomte.fr>
Date: Mon, 23 Oct 2017 19:23:13 +0000 (+0200)
Subject: ThreadContext: define yield(), and use yield()/start() whenever possible.
X-Git-Tag: v3.18~397^2~21
X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/commitdiff_plain/0c956d214e807eec6b3d6d43ebf52d7752f11b1f?ds=sidebyside

ThreadContext: define yield(), and use yield()/start() whenever possible.
---

diff --git a/src/kernel/context/ContextThread.cpp b/src/kernel/context/ContextThread.cpp
index ebcdfbef65..4eac4a52c9 100644
--- a/src/kernel/context/ContextThread.cpp
+++ b/src/kernel/context/ContextThread.cpp
@@ -89,9 +89,9 @@ ThreadContext* ThreadContextFactory::create_maestro(std::function<void()> code,
     return this->new_context<ThreadContext>(std::move(code), nullptr, process, true);
 }
 
-ThreadContext::ThreadContext(std::function<void()> code,
-    void_pfn_smxprocess_t cleanup, smx_actor_t process, bool maestro)
-  : AttachContext(std::move(code), cleanup, process)
+ThreadContext::ThreadContext(std::function<void()> code, void_pfn_smxprocess_t cleanup, smx_actor_t process,
+                             bool maestro)
+    : AttachContext(std::move(code), cleanup, process), is_maestro_(maestro)
 {
   // We do not need the semaphores when maestro is in main,
   // but creating them anyway simplifies things when maestro is externalized
@@ -147,9 +147,7 @@ void *ThreadContext::wrapper(void *param)
   /* Tell the maestro we are starting, and wait for its green light */
   xbt_os_sem_release(context->end_);
 
-  xbt_os_sem_acquire(context->begin_);
-  if (smx_ctx_thread_sem)       /* parallel run */
-    xbt_os_sem_acquire(smx_ctx_thread_sem);
+  context->start();
 
   try {
     (*context)();
@@ -158,10 +156,8 @@ void *ThreadContext::wrapper(void *param)
     XBT_DEBUG("Caught a StopRequest");
   }
 
-  if (smx_ctx_thread_sem)
-    xbt_os_sem_release(smx_ctx_thread_sem);
   // Signal to the maestro that it has finished:
-  xbt_os_sem_release(context->end_);
+  context->yield();
 
 #ifndef WIN32
   stack.ss_flags = SS_DISABLE;
@@ -186,11 +182,11 @@ void *ThreadContext::maestro_wrapper(void *param)
   xbt_os_sem_release(context->end_);
 
   // Wait for the caller to give control back to us:
-  xbt_os_sem_acquire(context->begin_);
+  context->start();
   (*context)();
 
   // Tell main that we have finished:
-  xbt_os_sem_release(context->end_);
+  context->yield();
 
 #ifndef WIN32
   stack.ss_flags = SS_DISABLE;
@@ -202,10 +198,17 @@ void *ThreadContext::maestro_wrapper(void *param)
 void ThreadContext::start()
 {
   xbt_os_sem_acquire(this->begin_);
-  if (smx_ctx_thread_sem)       /* parallel run */
+  if (not is_maestro_ && smx_ctx_thread_sem) /* parallel run */
     xbt_os_sem_acquire(smx_ctx_thread_sem);
 }
 
+void ThreadContext::yield()
+{
+  if (not is_maestro_ && smx_ctx_thread_sem) /* parallel run */
+    xbt_os_sem_release(smx_ctx_thread_sem);
+  xbt_os_sem_release(this->end_);
+}
+
 void ThreadContext::stop()
 {
   Context::stop();
@@ -214,12 +217,8 @@ void ThreadContext::stop()
 
 void ThreadContext::suspend()
 {
-  if (smx_ctx_thread_sem)
-    xbt_os_sem_release(smx_ctx_thread_sem);
-  xbt_os_sem_release(this->end_);
-  xbt_os_sem_acquire(this->begin_);
-  if (smx_ctx_thread_sem)
-    xbt_os_sem_acquire(smx_ctx_thread_sem);
+  this->yield();
+  this->start();
 }
 
 void ThreadContext::attach_start()
@@ -227,14 +226,14 @@ void ThreadContext::attach_start()
   // We're breaking the layers here by depending on the upper layer:
   ThreadContext* maestro = (ThreadContext*) simix_global->maestro_process->context;
   xbt_os_sem_release(maestro->begin_);
+  xbt_assert(not this->is_maestro_);
   this->start();
 }
 
 void ThreadContext::attach_stop()
 {
-  if (smx_ctx_thread_sem)
-    xbt_os_sem_release(smx_ctx_thread_sem);
-  xbt_os_sem_release(this->end_);
+  xbt_assert(not this->is_maestro_);
+  this->yield();
 
   ThreadContext* maestro = (ThreadContext*) simix_global->maestro_process->context;
   xbt_os_sem_acquire(maestro->end_);
diff --git a/src/kernel/context/ContextThread.hpp b/src/kernel/context/ContextThread.hpp
index 3449f88a59..62d8191257 100644
--- a/src/kernel/context/ContextThread.hpp
+++ b/src/kernel/context/ContextThread.hpp
@@ -22,9 +22,7 @@ class ThreadContextFactory;
 class ThreadContext : public AttachContext {
 public:
   friend ThreadContextFactory;
-  ThreadContext(std::function<void()> code,
-          void_pfn_smxprocess_t cleanup_func,
-          smx_actor_t process, bool maestro =false);
+  ThreadContext(std::function<void()> code, void_pfn_smxprocess_t cleanup_func, smx_actor_t process, bool maestro);
   ~ThreadContext() override;
   void stop() override;
   void suspend() override;
@@ -37,11 +35,13 @@ private:
   xbt_os_sem_t begin_ = nullptr;
   /** Semaphore used to schedule/unschedule */
   xbt_os_sem_t end_ = nullptr;
+  bool is_maestro_;
 
   static void* wrapper(void *param);
   static void* maestro_wrapper(void *param);
 public:
   void start();
+  void yield();
 };
 
 class ThreadContextFactory : public ContextFactory {