channel: Filter unicast message receivers at transmission instead of reception

This lowers the performance cost of the receive operation.

1 files changed, 17 insertions, 11 deletions

diff --git a/src/channel.zig b/src/channel.zig
index 061331e..d22bc77 100644
--- a/src/channel.zig
+++ b/src/channel.zig
@@ -13,7 +13,6 @@ pub const Error = error{
 pub const Message = struct {
     bytes: []const u8,
     refcount: usize = 1,
-    process_filter: u16,
     sender: u16,
 
     fn addReference(self: *Message) !void {
@@ -63,18 +62,29 @@ pub fn pass(pid: u16, id: usize, receiver: u16, identify: bool, bytes: []const u
 
     message.* = .{
         .bytes = bytes,
-        .process_filter = receiver,
         .sender = if (identify) pid else 0,
     };
 
+    if (receiver != 0) {
+        try message.addReference();
+        errdefer message.dropReference();
+
+        try passTo(joined.getPtr(receiver) orelse return, id, message);
+        return;
+    }
+
     var it = joined.iterator();
     while (it.next()) |queues| {
-        if (queues.value_ptr.getPtr(id)) |messages| {
-            try message.addReference();
-            errdefer message.dropReference();
+        try message.addReference();
+        errdefer message.dropReference();
 
-            try enqueue(messages, message);
-        }
+        try passTo(queues.value_ptr, id, message);
+    }
+}
+
+fn passTo(queues: *Queues, id: usize, message: *Message) !void {
+    if (queues.getPtr(id)) |messages| {
+        try enqueue(messages, message);
     }
 }
 
@@ -86,10 +96,6 @@ pub fn receive(pid: u16, id: usize, sender: ?*u16, buffer: []u8) !usize {
     defer alloc.destroy(message);
     defer message.data.dropReference();
 
-    if (message.data.process_filter != pid and message.data.process_filter != 0) {
-        return Error.WouldBlock;
-    }
-
     if (sender) |sender_id| sender_id.* = message.data.sender;
 
     const len = @min(buffer.len, message.data.bytes.len);