1 files changed, 75 insertions, 0 deletions
diff --git a/lua/mason-core/async/control.lua b/lua/mason-core/async/control.lua
new file mode 100644
index 00000000..3252c070
--- /dev/null
+++ b/lua/mason-core/async/control.lua
@@ -0,0 +1,75 @@
+local a = require "mason-core.async"
+
+---@class Condvar
+local Condvar = {}
+Condvar.__index = Condvar
+
+function Condvar.new()
+    return setmetatable({ handles = {}, queue = {}, is_notifying = false }, Condvar)
+end
+
+---@async
+function Condvar:wait()
+    a.wait(function(resolve)
+        if self.is_notifying then
+            self.queue[resolve] = true
+        else
+            self.handles[resolve] = true
+        end
+    end)
+end
+
+function Condvar:notify_all()
+    self.is_notifying = true
+    for handle in pairs(self.handles) do
+        handle()
+    end
+    self.handles = self.queue
+    self.queue = {}
+    self.is_notifying = false
+end
+
+local Permit = {}
+Permit.__index = Permit
+
+function Permit.new(semaphore)
+    return setmetatable({ semaphore = semaphore }, Permit)
+end
+
+function Permit:forget()
+    local semaphore = self.semaphore
+    semaphore.permits = semaphore.permits + 1
+
+    if semaphore.permits > 0 and #semaphore.handles > 0 then
+        semaphore.permits = semaphore.permits - 1
+        local release = table.remove(semaphore.handles, 1)
+        release(Permit.new(semaphore))
+    end
+end
+
+---@class Semaphore
+local Semaphore = {}
+Semaphore.__index = Semaphore
+
+---@param permits integer
+function Semaphore.new(permits)
+    return setmetatable({ permits = permits, handles = {} }, Semaphore)
+end
+
+---@async
+function Semaphore:acquire()
+    if self.permits > 0 then
+        self.permits = self.permits - 1
+    else
+        return a.wait(function(resolve)
+            table.insert(self.handles, resolve)
+        end)
+    end
+
+    return Permit.new(self)
+end
+
+return {
+    Condvar = Condvar,
+    Semaphore = Semaphore,
+}