X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/47619e4bb47a259821ad1b37cca80a91184fe79c..2ba24bc5763918ed2a233ce2071324d0d1b9d024:/src/simix/smx_context.c

diff --git a/src/simix/smx_context.c b/src/simix/smx_context.c
index 868354753c..ca29ef5915 100644
--- a/src/simix/smx_context.c
+++ b/src/simix/smx_context.c
@@ -1,7 +1,7 @@
 /* a fast and simple context switching library                              */
 
-/* Copyright (c) 2004-2008 the SimGrid team.                                */
-/* All rights reserved.                                                     */
+/* Copyright (c) 2009, 2010. The SimGrid Team.
+ * All rights reserved.                                                     */
 
 /* This program is free software; you can redistribute it and/or modify it
  * under the terms of the license (GNU LGPL) which comes with this package. */
@@ -9,30 +9,75 @@
 #include "portable.h"
 #include "xbt/log.h"
 #include "xbt/swag.h"
-#include "private.h"
+#include "xbt/xbt_os_thread.h"
+#include "src/simix/private.h"
+#include "simix/context.h"
+#include "gras_config.h"
 
-XBT_LOG_NEW_DEFAULT_SUBCATEGORY(simix_context, simix, "Context switching mecanism");
+XBT_LOG_NEW_DEFAULT_SUBCATEGORY(simix_context, simix,
+                                "Context switching mecanism");
 
+char* smx_context_factory_name = NULL; /* factory name specified by --cfg=contexts/factory:value */
+smx_ctx_factory_initializer_t smx_factory_initializer_to_use = NULL;
+int smx_context_stack_size = 128 * 1024;
 
-/**
- * This function is call by SIMIX_global_init() to initialize the context module.
+#ifdef HAVE_THREAD_LOCAL_STORAGE
+__thread smx_context_t smx_current_context;
+#else
+smx_context_t smx_current_context; /* define it anyway, will be used in non-parallel mode */
+static xbt_os_thread_key_t smx_current_context_key = 0;
+#endif
+
+static int smx_parallel_contexts = 1;
+static int smx_parallel_threshold = 2;
+
+/** 
+ * This function is called by SIMIX_global_init() to initialize the context module.
  */
 void SIMIX_context_mod_init(void)
 {
   if (!simix_global->context_factory) {
-  /* select context factory to use to create the context(depends of the macro definitions) */
-
-#ifdef CONTEXT_THREADS
-    /* context switch based os thread */
-    SIMIX_ctx_thread_factory_init(&simix_global->context_factory);
-#elif !defined(WIN32)
-    /* context switch based ucontext */
-    SIMIX_ctx_sysv_factory_init(&simix_global->context_factory);
+    /* select the context factory to use to create the contexts */
+    if (smx_factory_initializer_to_use) {
+      (*smx_factory_initializer_to_use)(&(simix_global->context_factory));
+    }
+    else { /* use the factory specified by --cfg=contexts/factory:value */
+
+      if (smx_context_factory_name == NULL) {
+        /* use the default factory */
+#ifdef CONTEXT_UCONTEXT
+        SIMIX_ctx_sysv_factory_init(&simix_global->context_factory);
+#else
+        SIMIX_ctx_thread_factory_init(&simix_global->context_factory);
+#endif
+      }
+      else if (!strcmp(smx_context_factory_name, "ucontext")) {
+        /* use ucontext */
+#ifdef CONTEXT_UCONTEXT
+        SIMIX_ctx_sysv_factory_init(&simix_global->context_factory);
 #else
-    /* context switch is not allowed on Windows */
-#error ERROR [__FILE__, line __LINE__]: no context based implementation specified.
+        xbt_die("The context factory 'ucontext' unavailable on your system");
 #endif
+      }
+      else if (!strcmp(smx_context_factory_name, "thread")) {
+	/* use os threads (either pthreads or windows ones) */
+        SIMIX_ctx_thread_factory_init(&simix_global->context_factory);
+      }
+      else if (!strcmp(smx_context_factory_name, "raw")) {
+	/* use raw contexts */
+	SIMIX_ctx_raw_factory_init(&simix_global->context_factory);
+      }
+      else {
+        xbt_die("Invalid context factory specified");
+      }
+    }
   }
+
+#if defined(CONTEXT_THREADS) && !defined(HAVE_THREAD_LOCAL_STORAGE)
+  /* the __thread storage class is not available on this platform:
+   * use getspecific/setspecific instead to store the current context in each thread */
+  xbt_os_thread_key_create(&smx_current_context_key);
+#endif
 }
 
 /**
@@ -42,75 +87,104 @@ void SIMIX_context_mod_exit(void)
 {
   if (simix_global->context_factory) {
     smx_pfn_context_factory_finalize_t finalize_factory;
-    
+
     /* finalize the context factory */
     finalize_factory = simix_global->context_factory->finalize;
     (*finalize_factory) (&simix_global->context_factory);
   }
+  xbt_dict_remove((xbt_dict_t) _surf_cfg_set,"contexts/factory");
 }
 
 /**
- * This function is used to change the context factory.
- * Warning: it destroy all the existing processes (even for maestro), and it
- * will create a new maestro process using the new context factory.
+ * \brief Sets the number of parallel threads to use
+ * for the user contexts.
+ *
+ * This function should be called before initializing SIMIX.
+ * A value of 1 means no parallelism.
+ * If the value is greater than 1, the thread support must be enabled.
+ *
+ * \param nb_threads the number of threads to use
  */
-int SIMIX_context_select_factory(const char *name)
-{
-  /* if a context factory is already instantiated and it is different from the
-     newly selected one, then kill all the processes, exit the context module
-     and initialize the new factory.
-  */
-  if (simix_global->context_factory != NULL) {
-    if (strcmp(simix_global->context_factory->name, name)){
-
-      SIMIX_process_killall();
-      
-      /* kill maestro process */
-      SIMIX_context_free(simix_global->maestro_process->context);
-      free(simix_global->maestro_process);  
-      simix_global->maestro_process = NULL;
-
-      SIMIX_context_mod_exit();
-    }
-    else
-      /* the same context factory is requested return directly */
-      return 0;
+XBT_INLINE void SIMIX_context_set_nthreads(int nb_threads) {
+
+  xbt_assert(nb_threads > 0, "Invalid number of parallel threads: %d", nb_threads);
+
+  if (nb_threads > 1) {
+#ifndef CONTEXT_THREADS
+    THROWF(arg_error, 0, "No thread support for parallel context execution");
+#endif
   }
-  
-  /* init the desired factory */
-  SIMIX_context_init_factory_by_name(&simix_global->context_factory, name);
 
-  __SIMIX_create_maestro_process ();
-  
-  return 0;
+  smx_parallel_contexts = nb_threads;
+}
+
+/**
+ * \brief Returns the number of parallel threads used
+ * for the user contexts.
+ * \return the number of threads (1 means no parallelism)
+ */
+XBT_INLINE int SIMIX_context_get_nthreads(void) {
+  return smx_parallel_contexts;
 }
 
 /**
- * Initializes a context factory given by its name
+ * \brief Returns whether some parallel threads are used
+ * for the user contexts.
+ * \return 1 if parallelism is used
  */
-void SIMIX_context_init_factory_by_name(smx_context_factory_t * factory,
-                                        const char *name)
+XBT_INLINE int SIMIX_context_is_parallel(void) {
+  return smx_parallel_contexts > 1;
+}
+
+/**
+ * \brief Sets the threshold above which user processes are run in parallel.
+ *
+ * If the number of threads is set to 1, there is no parallelism and this
+ * threshold has no effect.
+ *
+ * \param threshold when the number of user processes ready to run is above
+ * this threshold, they are run in parallel
+ */
+XBT_INLINE void SIMIX_context_set_parallel_threshold(int threshold) {
+  smx_parallel_threshold = threshold;
+}
+
+/**
+ * \brief Returns the threshold above which user processes are run in parallel.
+ *
+ * If the number of threads is set to 1, there is no parallelism and this
+ * threshold has no effect.
+ *
+ * \return when the number of user processes ready to run is above
+ * this threshold, they are run in parallel
+ */
+XBT_INLINE int SIMIX_context_get_parallel_threshold(void) {
+  return smx_parallel_threshold;
+}
+
+/**
+ * \brief Returns the current context of this thread.
+ * \return the current context of this thread
+ */
+XBT_INLINE smx_context_t SIMIX_context_get_current(void)
 {
-  if (!strcmp(name, "java"))
-#ifdef HAVE_JAVA     
-    SIMIX_ctx_java_factory_init(factory);
-#else
-    THROW0(not_found_error, 0, "Factory 'Java' does not exist: Java support was not compiled in the SimGrid library");
-#endif /* HAVE_JAVA */
-   
-  else if (!strcmp(name, "thread"))
-#ifdef CONTEXT_THREADS
-    SIMIX_ctx_thread_factory_init(factory);
+#ifdef HAVE_THREAD_LOCAL_STORAGE
+  return smx_current_context;
 #else
-    THROW0(not_found_error, 0, "Factory 'thread' does not exist: thread support was not compiled in the SimGrid library");
-#endif /* CONTEXT_THREADS */
-   
-  else if (!strcmp(name, "sysv"))
-#if !defined(WIN32) && !defined(CONTEXT_THREADS)
-    SIMIX_ctx_sysv_factory_init(factory);
+  return xbt_os_thread_get_specific(smx_current_context_key);
+#endif
+}
+
+/**
+ * \brief Sets the current context of this thread.
+ * \param context the context to set
+ */
+XBT_INLINE void SIMIX_context_set_current(smx_context_t context)
+{
+#ifdef HAVE_THREAD_LOCAL_STORAGE
+  smx_current_context = context;
 #else
-    THROW0(not_found_error, 0, "Factory 'sysv' does not exist: no System V thread support under Windows");
-#endif   
-  else
-    THROW1(not_found_error, 0, "Factory '%s' does not exist", name);
+  xbt_os_thread_set_specific(smx_current_context_key, context);
+#endif
 }
+