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local a = require "mason-core.async"
---@class Condvar
local Condvar = {}
Condvar.__index = Condvar
function Condvar.new()
return setmetatable({ handles = {} }, Condvar)
end
---@async
function Condvar:wait()
a.wait(function(resolve)
self.handles[#self.handles + 1] = resolve
end)
end
function Condvar:notify()
local handle = table.remove(self.handles)
pcall(handle)
end
function Condvar:notify_all()
while #self.handles > 0 do
self:notify()
end
self.handles = {}
end
---@class Permit
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
---@class OneShotChannel
---@field has_sent boolean
---@field value any
---@field condvar Condvar
local OneShotChannel = {}
OneShotChannel.__index = OneShotChannel
function OneShotChannel.new()
return setmetatable({
has_sent = false,
value = nil,
condvar = Condvar.new(),
}, OneShotChannel)
end
function OneShotChannel:is_closed()
return self.has_sent
end
function OneShotChannel:send(...)
assert(not self.has_sent, "Oneshot channel can only send once.")
self.has_sent = true
self.value = { ... }
self.condvar:notify_all()
self.condvar = nil
end
function OneShotChannel:receive()
if not self.has_sent then
self.condvar:wait()
end
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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