Add Channel:peek()

2 files changed, 12 insertions, 0 deletions

diff --git a/builtins/channel.c b/builtins/channel.c
index f47a0b11..9360bcfc 100644
--- a/builtins/channel.c
+++ b/builtins/channel.c
@@ -68,6 +68,16 @@ public void Channel$get(channel_t *channel, void *out, int64_t item_size, int64_
     (void)pthread_cond_signal(&channel->cond);
 }
 
+public void Channel$peek(channel_t *channel, void *out, int64_t item_size)
+{
+    (void)pthread_mutex_lock(&channel->mutex);
+    while (channel->items.length == 0)
+        pthread_cond_wait(&channel->cond, &channel->mutex);
+    memcpy(out, channel->items.data, item_size);
+    (void)pthread_mutex_unlock(&channel->mutex);
+    (void)pthread_cond_signal(&channel->cond);
+}
+
 public array_t Channel$view(channel_t *channel)
 {
     (void)pthread_mutex_lock(&channel->mutex);
diff --git a/builtins/channel.h b/builtins/channel.h
index 3b2d2c16..b8282374 100644
--- a/builtins/channel.h
+++ b/builtins/channel.h
@@ -15,6 +15,8 @@ void Channel$give(channel_t *channel, const void *item, int64_t padded_item_size
 void Channel$give_all(channel_t *channel, array_t to_give, int64_t padded_item_size);
 void Channel$get(channel_t *channel, void *out, int64_t item_size, int64_t padded_item_size);
 #define Channel$get_value(channel, t, padded_item_size) ({ t _val; Channel$get(channel, &_val, sizeof(t), padded_item_size); _val; })
+void Channel$peek(channel_t *channel, void *out, int64_t item_size);
+#define Channel$peek_value(channel, t) ({ t _val; Channel$peek(channel, &_val, sizeof(t)); _val; })
 void Channel$clear(channel_t *channel);
 array_t Channel$view(channel_t *channel);
 uint32_t Channel$hash(const channel_t **channel, const TypeInfo *type);