concurrency/future: Store min_wait as an integer to avoid divisions.HEADmaster

2 files changed, 12 insertions, 21 deletions

diff --git a/libdimension/concurrency/future.c b/libdimension/concurrency/future.c
index 90ffa24..7ef32c0 100644
--- a/libdimension/concurrency/future.c
+++ b/libdimension/concurrency/future.c
@@ -1,5 +1,5 @@
 /*************************************************************************
- * Copyright (C) 2009-2014 Tavian Barnes <tavianator@tavianator.com>     *
+ * Copyright (C) 2009-2015 Tavian Barnes <tavianator@tavianator.com>     *
  *                                                                       *
  * This file is part of The Dimension Library.                           *
  *                                                                       *
@@ -46,7 +46,7 @@ dmnsn_new_future(void)
   dmnsn_initialize_mutex(&future->mutex);
   dmnsn_initialize_cond(&future->cond);
 
-  future->min_wait = 1.0;
+  future->min_wait = 1;
 
   future->nthreads = future->nrunning = 1;
   future->npaused = 0;
@@ -101,17 +101,6 @@ dmnsn_future_cancel(dmnsn_future *future)
   pthread_cancel(future->thread);
 }
 
-/**
- * Get the current progress, without locking anything.
- *
- * future->mutex must be locked for this call to be safe.
- */
-static inline double
-dmnsn_future_progress_unlocked(const dmnsn_future *future)
-{
-  return (double)future->progress/future->total;
-}
-
 // Get the current progress of the worker thread, in [0.0, 1.0]
 double
 dmnsn_future_progress(const dmnsn_future *future)
@@ -120,7 +109,7 @@ dmnsn_future_progress(const dmnsn_future *future)
   double progress;
 
   dmnsn_lock_mutex(&mfuture->mutex);
-    progress = dmnsn_future_progress_unlocked(mfuture);
+    progress = (double)future->progress/future->total;
   dmnsn_unlock_mutex(&mfuture->mutex);
 
   return progress;
@@ -147,10 +136,11 @@ dmnsn_future_wait(const dmnsn_future *future, double progress)
   dmnsn_future *mfuture = MUTATE(future);
 
   dmnsn_lock_mutex(&mfuture->mutex);
-    while (dmnsn_future_progress_unlocked(mfuture) < progress) {
+    size_t iprogress = progress*mfuture->total;
+    while (mfuture->progress < iprogress) {
       // Set the minimum waited-on value
-      if (progress < mfuture->min_wait) {
-        mfuture->min_wait = progress;
+      if (iprogress < mfuture->min_wait) {
+        mfuture->min_wait = iprogress;
       }
 
       dmnsn_cond_wait_safely(&mfuture->cond, &mfuture->mutex);
@@ -191,6 +181,7 @@ dmnsn_future_set_total(dmnsn_future *future, size_t total)
 {
   dmnsn_lock_mutex(&future->mutex);
     future->total = total;
+    future->min_wait = total;
   dmnsn_unlock_mutex(&future->mutex);
 }
 
@@ -214,8 +205,8 @@ dmnsn_future_increment(dmnsn_future *future)
   dmnsn_lock_mutex(&future->mutex);
     ++future->progress;
 
-    if (dmnsn_future_progress_unlocked(future) >= future->min_wait) {
-      future->min_wait = 1.0;
+    if (future->progress >= future->min_wait) {
+      future->min_wait = future->total;
       dmnsn_cond_broadcast(&future->cond);
     }
 
diff --git a/libdimension/internal/future.h b/libdimension/internal/future.h
index 047523e..5f25027 100644
--- a/libdimension/internal/future.h
+++ b/libdimension/internal/future.h
@@ -1,5 +1,5 @@
 /*************************************************************************
- * Copyright (C) 2010-2014 Tavian Barnes <tavianator@tavianator.com>     *
+ * Copyright (C) 2010-2015 Tavian Barnes <tavianator@tavianator.com>     *
  *                                                                       *
  * This file is part of The Dimension Library.                           *
  *                                                                       *
@@ -42,7 +42,7 @@ struct dmnsn_future {
   pthread_cond_t cond;
 
   /// Minimum waited-on value.
-  double min_wait;
+  size_t min_wait;
 
   /// Number of threads working on the future's background task.
   unsigned int nthreads;