From b5bb138312dbd3f7729197ca659cbe5221d36a03 Mon Sep 17 00:00:00 2001
From: William Boman <william@redwill.se>
Date: Thu, 17 Aug 2023 19:34:23 +0200
Subject: chore(async): add Channel (#1456)

---
 lua/mason-core/async/control.lua | 62 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 60 insertions(+), 2 deletions(-)

(limited to 'lua/mason-core/async/control.lua')

diff --git a/lua/mason-core/async/control.lua b/lua/mason-core/async/control.lua
index c9479540..57aa88db 100644
--- a/lua/mason-core/async/control.lua
+++ b/lua/mason-core/async/control.lua
@@ -15,9 +15,14 @@ function Condvar:wait()
     end)
 end
 
+function Condvar:notify()
+    local handle = table.remove(self.handles)
+    pcall(handle)
+end
+
 function Condvar:notify_all()
-    for _, handle in ipairs(self.handles) do
-        pcall(handle)
+    while #self.handles > 0 do
+        self:notify()
     end
     self.handles = {}
 end
@@ -97,8 +102,61 @@ function OneShotChannel:receive()
     return unpack(self.value)
 end
 
+---@class Channel
+---@field private condvar Condvar
+---@field private buffer any?
+---@field is_closed boolean
+local Channel = {}
+Channel.__index = Channel
+function Channel.new()
+    return setmetatable({
+        condvar = Condvar.new(),
+        buffer = nil,
+        is_closed = false,
+    }, Channel)
+end
+
+function Channel:close()
+    self.is_closed = true
+end
+
+---@async
+function Channel:send(value)
+    assert(not self.is_closed, "Channel is closed.")
+    while self.buffer ~= nil do
+        self.condvar:wait()
+    end
+    self.buffer = value
+    self.condvar:notify()
+    while self.buffer ~= nil do
+        self.condvar:wait()
+    end
+end
+
+---@async
+function Channel:receive()
+    assert(not self.is_closed, "Channel is closed.")
+    while self.buffer == nil do
+        self.condvar:wait()
+    end
+    local value = self.buffer
+    self.buffer = nil
+    self.condvar:notify()
+    return value
+end
+
+---@async
+function Channel:iter()
+    return function()
+        while not self.is_closed do
+            return self:receive()
+        end
+    end
+end
+
 return {
     Condvar = Condvar,
     Semaphore = Semaphore,
     OneShotChannel = OneShotChannel,
+    Channel = Channel,
 }
-- 
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