From 7b166e5296dce18767c16f311ee735974caa415a Mon Sep 17 00:00:00 2001
From: Heng Li <lh3@me.com>
Date: Wed, 9 Oct 2013 23:52:13 -0400
Subject: [PATCH] pass item index to function calls

kt_for() to be replaced by more complex but more versatile APIs
---
 kthread.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kthread.c b/kthread.c
index 0833cfd..9ebdc18 100644
--- a/kthread.c
+++ b/kthread.c
@@ -70,7 +70,7 @@ typedef struct {
 	int n, size; // n: number of workers; size: size of each items element
 	void *shared;
 	void *items;
-	int (*func)(void*,void*);
+	int (*func)(void*,int,void*);
 	struct ktf_worker_t *w;
 	int finished;
 } kt_for_t;
@@ -97,7 +97,7 @@ static void *ktf_worker(void *data)
 	for (;;) {
 		int k = -1;
 		if (dq_deq(w->q, 1, &k) < 0) k = steal_work(w->f);
-		if (k >= 0) w->f->func(w->f->shared, (uint8_t*)w->f->items + w->f->size * k);
+		if (k >= 0) w->f->func(w->f->shared, k, (uint8_t*)w->f->items + w->f->size * k);
 		else if (w->f->finished) break;
 	}
 	return 0;
@@ -107,7 +107,7 @@ static void *ktf_worker(void *data)
  * Parallelize a simple "for" loop
  *
  * @param n_threads    total number of threads
- * @param func         processing function
+ * @param func         function in the form of func(void *shared, int item_id, void *item);
  * @param shared       shared data used by $func
  * @param n_items      number of items to process
  * @param item_size    size of each item
@@ -124,7 +124,7 @@ static void *ktf_worker(void *data)
  *
  *   ht_for(n_threads, func, shared, n_items, sizeof(item_type), items);
  */
-void kt_for(int n_threads, int (*func)(void*,void*), void *shared, int n_items, int item_size, void *items)
+void kt_for(int n_threads, int (*func)(void*,int,void*), void *shared, int n_items, int item_size, void *items)
 {
 	kt_for_t *f;
 	pthread_t *tid;
@@ -147,10 +147,10 @@ void kt_for(int n_threads, int (*func)(void*,void*), void *shared, int n_items,
 		for (i = 0, min = 1<<dq_bits, min_i = -1; i < f->n; ++i) // find the worker with the lowest load
 			if (min > dq_size(f->w[i].q)) min = dq_size(f->w[i].q), min_i = i;
 		if (min < 1<<dq_bits) dq_enq(f->w[min_i].q, 0, &k);
-		else func(shared, (uint8_t*)f->items + f->size * k);
+		else f->func(shared, k, (uint8_t*)f->items + f->size * k);
 	}
 	f->finished = 1;
-	while ((k = steal_work(f)) >= 0) func(shared, (uint8_t*)f->items + f->size * k); // help the unfinished workers
+	while ((k = steal_work(f)) >= 0) func(shared, k, (uint8_t*)f->items + f->size * k); // help the unfinished workers
 
 	for (i = 0; i < f->n; ++i) pthread_join(tid[i], 0);
 	for (i = 0; i < f->n; ++i) dq_destroy(f->w[i].q);
-- 
2.47.3