From 2f46ead3ad45a4475988c6a45332949edc365ce4 Mon Sep 17 00:00:00 2001
From: Jianhui Zhao <zhaojh329@gmail.com>
Date: Mon, 3 Jun 2024 14:36:27 +0800
Subject: [PATCH] feat(sync): add return value for cond:signal and
 cond:broadcast

This is useful when user want to known whether any coroutines
have been awakened.

Signed-off-by: Jianhui Zhao <zhaojh329@gmail.com>
---
 examples/sync_cond.lua | 7 +++++--
 sync.lua               | 9 +++++++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/examples/sync_cond.lua b/examples/sync_cond.lua
index 1b89735..886869b 100755
--- a/examples/sync_cond.lua
+++ b/examples/sync_cond.lua
@@ -15,10 +15,13 @@ end
 
 -- wakes one coroutine waiting on the cond
 time.at(1, function()
-    cond:signal()
+    if cond:signal() then
+        print('waked one coroutine')
+    end
 end)
 
 -- wakes all coroutines waiting on the cond
 time.at(3, function()
-    cond:broadcast()
+    local cnt = cond:broadcast()
+    print('waked', cnt, 'coroutines')
 end)
diff --git a/sync.lua b/sync.lua
index 5ff6aa2..3fa8505 100644
--- a/sync.lua
+++ b/sync.lua
@@ -17,22 +17,31 @@ function cond_methods:wait(timeout)
 end
 
 -- wakes one coroutine waiting on the cond, if there is any.
+-- returns true if one coroutine was waked
 function cond_methods:signal()
     local watchers = self.watchers
 
     if #watchers > 0 then
         watchers[1]:send()
         table.remove(watchers, 1)
+        return true
     end
+
+    return false
 end
 
 -- wakes all coroutines waiting on the cond
+-- returns the number of awakened coroutines
 function cond_methods:broadcast()
+    local cnt = #self.watchers
+
     for _, w in ipairs(self.watchers) do
         w:send()
     end
 
     self.watchers = {}
+
+    return cnt
 end
 
 local cond_mt = { __index = cond_methods }