X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/1c86ddc00bb20b4f3779a815f732a1c1cb14139a..ccc485f3688249e70503ad250cb065b5b6d7748f:/src/xbt/parmap.c

diff --git a/src/xbt/parmap.c b/src/xbt/parmap.c
index 5801828377..9f2f35bd49 100644
--- a/src/xbt/parmap.c
+++ b/src/xbt/parmap.c
@@ -5,15 +5,15 @@
  * under the terms of the license (GNU LGPL) which comes with this package. */
 #include "gras_config.h"
 #include <unistd.h>
+
 #ifndef _XBT_WIN32
 #include <sys/syscall.h>
 #endif
 
 #ifdef HAVE_FUTEX_H
-	#include <linux/futex.h>
-#else
-	#include "xbt/xbt_os_thread.h"
+#include <linux/futex.h>
 #endif
+
 #include "xbt/parmap.h"
 #include "xbt/log.h"
 #include "xbt/function_types.h"
@@ -24,43 +24,62 @@
 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(xbt_parmap, xbt, "parmap: parallel map");
 XBT_LOG_NEW_SUBCATEGORY(xbt_parmap_unit, xbt_parmap, "parmap unit testing");
 
-typedef enum{
-  PARMAP_WORK = 0,
-  PARMAP_DESTROY
+typedef enum {
+  XBT_PARMAP_WORK = 0,
+  XBT_PARMAP_DESTROY
 } e_xbt_parmap_flag_t;
 
+static void xbt_parmap_set_mode(xbt_parmap_t parmap, e_xbt_parmap_mode_t mode);
+static void *xbt_parmap_worker_main(void *parmap);
+
+static void xbt_parmap_posix_start(xbt_parmap_t parmap);
+static void xbt_parmap_posix_end(xbt_parmap_t parmap);
+static void xbt_parmap_posix_signal(xbt_parmap_t parmap);
+static void xbt_parmap_posix_wait(xbt_parmap_t parmap);
+
 #ifdef HAVE_FUTEX_H
-typedef struct s_xbt_event{
-  int work;
-  int done;
-  unsigned int thread_counter;
-  unsigned int threads_to_wait;
-}s_xbt_event_t, *xbt_event_t;
-
-void xbt_event_init(xbt_event_t event);
-void xbt_event_signal(xbt_event_t event);
-void xbt_event_wait(xbt_event_t event);
-void xbt_event_end(xbt_event_t event);
+static void xbt_parmap_futex_start(xbt_parmap_t parmap);
+static void xbt_parmap_futex_end(xbt_parmap_t parmap);
+static void xbt_parmap_futex_signal(xbt_parmap_t parmap);
+static void xbt_parmap_futex_wait(xbt_parmap_t parmap);
+static void futex_wait(int *uaddr, int val);
+static void futex_wake(int *uaddr, int val);
 #endif
 
+static void xbt_parmap_busy_start(xbt_parmap_t parmap);
+static void xbt_parmap_busy_end(xbt_parmap_t parmap);
+static void xbt_parmap_busy_signal(xbt_parmap_t parmap);
+static void xbt_parmap_busy_wait(xbt_parmap_t parmap);
+
+
+/**
+ * \brief Parallel map structure
+ */
 typedef struct s_xbt_parmap {
-  e_xbt_parmap_flag_t status;
-#ifdef HAVE_FUTEX_H
-  xbt_event_t sync_event;
-#endif
-  unsigned int num_workers;
-  unsigned int workers_max_id;
-  void_f_pvoid_t fun;
-  xbt_dynar_t data;
-  unsigned int index;
+  e_xbt_parmap_flag_t status;      /**< is the parmap active or being destroyed? */
+  int work;                        /**< index of the current round (1 is the first) */
+  int done;                        /**< number of rounds already done (futexes only) */
+  unsigned int thread_counter;     /**< number of threads currently working */
+  unsigned int num_workers;        /**< total number of worker threads including the controller */
+  void_f_pvoid_t fun;              /**< function to run in parallel on each element of data */
+  xbt_dynar_t data;                /**< parameters to pass to fun in parallel */
+  unsigned int index;              /**< index of the next element of data to pick */
+
+  /* fields that depend on the synchronization mode */
+  e_xbt_parmap_mode_t mode;        /**< synchronization mode */
+  void (*start_f)(xbt_parmap_t);   /**< initializes the worker threads */
+  void (*end_f)(xbt_parmap_t);     /**< finalizes the worker threads */
+  void (*signal_f)(xbt_parmap_t);  /**< wakes the workers threads to process tasks */
+  void (*wait_f)(xbt_parmap_t);    /**< waits for more work */
 } s_xbt_parmap_t;
 
-static void *_xbt_parmap_worker_main(void *parmap);
-#ifdef HAVE_FUTEX_H
-	static void futex_wait(int *uaddr, int val);
-	static void futex_wake(int *uaddr, int val);
-#endif
-xbt_parmap_t xbt_parmap_new(unsigned int num_workers)
+/**
+ * \brief Creates a parallel map object
+ * \param num_workers number of worker threads to create
+ * \param mode how to synchronize the worker threads
+ * \return the parmap created
+ */
+xbt_parmap_t xbt_parmap_new(unsigned int num_workers, e_xbt_parmap_mode_t mode)
 {
   unsigned int i;
   xbt_os_thread_t worker = NULL;
@@ -69,49 +88,106 @@ xbt_parmap_t xbt_parmap_new(unsigned int num_workers)
 
   /* Initialize the thread pool data structure */
   xbt_parmap_t parmap = xbt_new0(s_xbt_parmap_t, 1);
-#ifdef HAVE_FUTEX_H
-  parmap->sync_event = xbt_new0(s_xbt_event_t, 1);
-#endif
+
   parmap->num_workers = num_workers;
-  parmap->status = PARMAP_WORK;
-#ifdef HAVE_FUTEX_H
-  parmap->sync_event->threads_to_wait = num_workers;
-#endif
+  parmap->status = XBT_PARMAP_WORK;
+  xbt_parmap_set_mode(parmap, mode);
+
   /* Create the pool of worker threads */
-  for(i=0; i < num_workers; i++){
-    worker = xbt_os_thread_create(NULL, _xbt_parmap_worker_main, parmap, NULL);
+  for (i = 0; i < num_workers - 1; i++) {
+    worker = xbt_os_thread_create(NULL, xbt_parmap_worker_main, parmap, NULL);
     xbt_os_thread_detach(worker);
   }
-#ifdef HAVE_FUTEX_H
-  xbt_event_init(parmap->sync_event);
-#endif
+  parmap->start_f(parmap);
   return parmap;
 }
 
+/**
+ * \brief Destroys a parmap
+ * \param parmap the parmap to destroy
+ */
 void xbt_parmap_destroy(xbt_parmap_t parmap)
-{ 
-  parmap->status = PARMAP_DESTROY;
+{
+  parmap->status = XBT_PARMAP_DESTROY;
+  parmap->signal_f(parmap);
+  xbt_free(parmap);
+}
+
+/**
+ * \brief Sets the synchronization mode of a parmap.
+ * \param parmap a parallel map object
+ * \param mode the synchronization mode
+ */
+static void xbt_parmap_set_mode(xbt_parmap_t parmap, e_xbt_parmap_mode_t mode)
+{
+  if (mode == XBT_PARMAP_DEFAULT) {
 #ifdef HAVE_FUTEX_H
-  xbt_event_signal(parmap->sync_event);
-  xbt_free(parmap->sync_event);
+    mode = XBT_PARMAP_FUTEX;
+#else
+    mode = XBT_PARMAP_POSIX;
 #endif
-  xbt_free(parmap);
+  }
+  parmap->mode = mode;
+
+  switch (mode) {
+
+    case XBT_PARMAP_POSIX:
+      parmap->start_f = xbt_parmap_posix_start;
+      parmap->end_f = xbt_parmap_posix_end;
+      parmap->signal_f = xbt_parmap_posix_signal;
+      parmap->wait_f = xbt_parmap_posix_wait;
+      break;
+
+
+    case XBT_PARMAP_FUTEX:
+#ifdef HAVE_FUTEX_H
+      parmap->start_f = xbt_parmap_futex_start;
+      parmap->end_f = xbt_parmap_futex_end;
+      parmap->signal_f = xbt_parmap_futex_signal;
+      parmap->wait_f = xbt_parmap_futex_wait;
+      break;
+#else
+      xbt_die("Futex is not available on this OS (maybe you are on a Mac).");
+#endif
+
+    case XBT_PARMAP_BUSY_WAIT:
+      parmap->start_f = xbt_parmap_busy_start;
+      parmap->end_f = xbt_parmap_busy_end;
+      parmap->signal_f = xbt_parmap_busy_signal;
+      parmap->wait_f = xbt_parmap_busy_wait;
+      break;
+
+    case XBT_PARMAP_DEFAULT:
+      THROW_IMPOSSIBLE;
+      break;
+  }
 }
 
- void xbt_parmap_apply(xbt_parmap_t parmap, void_f_pvoid_t fun, xbt_dynar_t data)
+/**
+ * \brief Applies a list of tasks in parallel.
+ * \param parmap a parallel map object
+ * \param fun the function to call in parallel
+ * \param data each element of this dynar will be passed as an argument to fun
+ */
+void xbt_parmap_apply(xbt_parmap_t parmap, void_f_pvoid_t fun, xbt_dynar_t data)
 {
-  /* Assign resources to worker threads*/
+  /* Assign resources to worker threads */
   parmap->fun = fun;
   parmap->data = data;
   parmap->index = 0;
-#ifdef HAVE_FUTEX_H
-  xbt_event_signal(parmap->sync_event);
-#endif
+  parmap->signal_f(parmap);
   XBT_DEBUG("Job done");
 }
 
-void* xbt_parmap_next(xbt_parmap_t parmap) {
-
+/**
+ * \brief Returns a next task to process.
+ *
+ * Worker threads call this function to get more work.
+ *
+ * \return the next task to process, or NULL if there is no more work
+ */
+void* xbt_parmap_next(xbt_parmap_t parmap)
+{
   unsigned int index = __sync_fetch_and_add(&parmap->index, 1);
   if (index < xbt_dynar_length(parmap->data)) {
     return xbt_dynar_get_as(parmap->data, index, void*);
@@ -119,43 +195,35 @@ void* xbt_parmap_next(xbt_parmap_t parmap) {
   return NULL;
 }
 
-unsigned long xbt_parmap_get_worker_id(xbt_parmap_t parmap) {
-  return (unsigned long) xbt_os_thread_get_extra_data();
-}
-
-static void *_xbt_parmap_worker_main(void *arg)
+/**
+ * \brief Main function of a worker thread.
+ * \param arg the parmap
+ */
+static void *xbt_parmap_worker_main(void *arg)
 {
-  unsigned int worker_id;
   xbt_parmap_t parmap = (xbt_parmap_t) arg;
 
-  /* Fetch a worker id */
-  worker_id = __sync_fetch_and_add(&parmap->workers_max_id, 1);
-  xbt_os_thread_set_extra_data((void*) (unsigned long) worker_id);
+  XBT_DEBUG("New worker thread created");
 
-  XBT_DEBUG("New worker thread created (%u)", worker_id);
-  
   /* Worker's main loop */
   while (1) {
-#ifdef HAVE_FUTEX_H
-    xbt_event_wait(parmap->sync_event);
-#endif
-    if (parmap->status == PARMAP_WORK) {
+    parmap->wait_f(parmap);
+    if (parmap->status == XBT_PARMAP_WORK) {
 
-      XBT_DEBUG("Worker %u got a job", worker_id);
+      XBT_DEBUG("Worker got a job");
 
       void* work = xbt_parmap_next(parmap);
-      if (work != NULL) {
+      while (work != NULL) {
         parmap->fun(work);
+        work = xbt_parmap_next(parmap);
       }
 
-      XBT_DEBUG("Worker %u has finished", worker_id);
+      XBT_DEBUG("Worker has finished");
 
     /* We are destroying the parmap */
     } else {
-#ifdef HAVE_FUTEX_H
-      xbt_event_end(parmap->sync_event);
-#endif
-      XBT_DEBUG("Shutting down worker %u", worker_id);
+      parmap->end_f(parmap);
+      XBT_DEBUG("Shutting down worker");
       return NULL;
     }
   }
@@ -173,50 +241,198 @@ static void futex_wake(int *uaddr, int val)
   XBT_VERB("Waking futex %p", uaddr);
   syscall(SYS_futex, uaddr, FUTEX_WAKE_PRIVATE, val, NULL, NULL, 0);
 }
+#endif
 
-void xbt_event_init(xbt_event_t event)
+static void xbt_parmap_posix_start(xbt_parmap_t parmap)
 {
-  int myflag = event->done;
-  if(event->thread_counter < event->threads_to_wait)
-    futex_wait(&event->done, myflag);
+  THROW_UNIMPLEMENTED;
 }
 
-void xbt_event_signal(xbt_event_t event)
+static void xbt_parmap_posix_end(xbt_parmap_t parmap)
 {
-  int myflag = event->done;
-  event->thread_counter = 0;
-  event->work++;
-  futex_wake(&event->work, event->threads_to_wait);
-  futex_wait(&event->done, myflag);
+  THROW_UNIMPLEMENTED;
 }
 
-void xbt_event_wait(xbt_event_t event)
+static void xbt_parmap_posix_signal(xbt_parmap_t parmap)
+{
+  THROW_UNIMPLEMENTED;
+}
+
+static void xbt_parmap_posix_wait(xbt_parmap_t parmap)
+{
+  THROW_UNIMPLEMENTED;
+}
+
+#ifdef HAVE_FUTEX_H
+/**
+ * \brief Starts the parmap: waits for all workers to be ready and returns.
+ *
+ * This function is called by the controller thread.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_futex_start(xbt_parmap_t parmap)
+{
+  int myflag = parmap->done;
+  __sync_fetch_and_add(&parmap->thread_counter, 1);
+  if (parmap->thread_counter < parmap->num_workers) {
+    /* wait for all workers to be ready */
+    futex_wait(&parmap->done, myflag);
+  }
+}
+
+/**
+ * \brief Ends the parmap: wakes the controller thread when all workers terminate.
+ *
+ * This function is called by all worker threads when they end (not including
+ * the controller).
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_futex_end(xbt_parmap_t parmap)
 {
-  int myflag;
   unsigned int mycount;
 
-  myflag = event->work;
-  mycount = __sync_add_and_fetch(&event->thread_counter, 1);
-  if(mycount == event->threads_to_wait){
-    event->done++;
-    futex_wake(&event->done, 1);
+  mycount = __sync_add_and_fetch(&parmap->thread_counter, 1);
+  if (mycount == parmap->num_workers) {
+    /* all workers have finished, wake the controller */
+    parmap->done++;
+    futex_wake(&parmap->done, 1);
+  }
+}
+
+/**
+ * \brief Wakes all workers and waits for them to finish the tasks.
+ *
+ * This function is called by the controller thread.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_futex_signal(xbt_parmap_t parmap)
+{
+  int myflag = parmap->done;
+  parmap->thread_counter = 0;
+  parmap->work++;
+
+  /* wake all workers */
+  futex_wake(&parmap->work, parmap->num_workers);
+
+  if (parmap->status == XBT_PARMAP_WORK) {
+    /* also work myself */
+    void* work = xbt_parmap_next(parmap);
+    while (work != NULL) {
+      parmap->fun(work);
+      work = xbt_parmap_next(parmap);
+    }
   }
 
-  futex_wait(&event->work, myflag);
+  unsigned int mycount = __sync_add_and_fetch(&parmap->thread_counter, 1);
+  if (mycount < parmap->num_workers) {
+    /* some workers have not finished yet */
+    futex_wait(&parmap->done, myflag);
+  }
 }
 
-void xbt_event_end(xbt_event_t event)
+/**
+ * \brief Waits for some work to process.
+ *
+ * This function is called by each worker thread (not including the controller)
+ * when it has no more work to do.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_futex_wait(xbt_parmap_t parmap)
 {
+  int myflag;
   unsigned int mycount;
 
-  mycount = __sync_add_and_fetch(&event->thread_counter, 1);
-  if(mycount == event->threads_to_wait){
-    event->done++;
-    futex_wake(&event->done, 1);
+  myflag = parmap->work;
+  mycount = __sync_add_and_fetch(&parmap->thread_counter, 1);
+  if (mycount == parmap->num_workers) {
+    /* all workers have finished, wake the controller */
+    parmap->done++;
+    futex_wake(&parmap->done, 1);
   }
+
+  /* wait for more work */
+  futex_wait(&parmap->work, myflag);
 }
 #endif
 
+/**
+ * \brief Starts the parmap: waits for all workers to be ready and returns.
+ *
+ * This function is called by the controller thread.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_busy_start(xbt_parmap_t parmap)
+{
+  __sync_fetch_and_add(&parmap->thread_counter, 1);
+  while (parmap->thread_counter < parmap->num_workers) {
+    xbt_os_thread_yield();
+  }
+}
+
+/**
+ * \brief Ends the parmap: wakes the controller thread when all workers terminate.
+ *
+ * This function is called by all worker threads when they end.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_busy_end(xbt_parmap_t parmap)
+{
+  __sync_add_and_fetch(&parmap->thread_counter, 1);
+}
+
+/**
+ * \brief Wakes all workers and waits for them to finish the tasks.
+ *
+ * This function is called by the controller thread.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_busy_signal(xbt_parmap_t parmap)
+{
+  parmap->thread_counter = 0;
+  parmap->work++;
+
+  if (parmap->status == XBT_PARMAP_WORK) {
+    /* also work myself */
+    void* work = xbt_parmap_next(parmap);
+    while (work != NULL) {
+      parmap->fun(work);
+      work = xbt_parmap_next(parmap);
+    }
+  }
+
+  /* I have finished, wait for the others */
+  __sync_add_and_fetch(&parmap->thread_counter, 1);
+  while (parmap->thread_counter < parmap->num_workers) {
+    xbt_os_thread_yield();
+  }
+}
+
+/**
+ * \brief Waits for some work to process.
+ *
+ * This function is called by each worker thread (not including the controller)
+ * when it has no more work to do.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_busy_wait(xbt_parmap_t parmap)
+{
+  int work = parmap->work;
+  __sync_add_and_fetch(&parmap->thread_counter, 1);
+
+  /* wait for more work */
+  while (parmap->work == work) {
+    xbt_os_thread_yield();
+  }
+}
+
 #ifdef SIMGRID_TEST
 #include "xbt.h"
 #include "xbt/ex.h"
@@ -224,8 +440,6 @@ void xbt_event_end(xbt_event_t event)
 XBT_TEST_SUITE("parmap", "Parallel Map");
 XBT_LOG_EXTERNAL_DEFAULT_CATEGORY(xbt_parmap_unit);
 
-
-
 xbt_parmap_t parmap;
 
 void fun(void *arg);
@@ -239,18 +453,22 @@ XBT_TEST_UNIT("basic", test_parmap_basic, "Basic usage")
 {
   xbt_test_add("Create the parmap");
 
-  unsigned long i,j;
+  unsigned long i, j;
   xbt_dynar_t data = xbt_dynar_new(sizeof(void *), NULL);
 
   /* Create the parallel map */
-  parmap = xbt_parmap_new(10);
-
-  for(j=0; j < 100; j++){
+#ifdef HAVE_FUTEX_H
+  parmap = xbt_parmap_new(10, XBT_PARMAP_FUTEX);
+#else
+  parmap = xbt_parmap_new(10, XBT_PARMAP_BUSY_WAIT);
+#endif
+  for (j = 0; j < 100; j++) {
     xbt_dynar_push_as(data, void *, (void *)j);
   }
 
-  for(i=0; i < 5; i++)
+  for (i = 0; i < 5; i++) {
     xbt_parmap_apply(parmap, fun, data);
+  }
 
   /* Destroy the parmap */
   xbt_parmap_destroy(parmap);