opus/sys/apis/sync.lua

local Sync = {
  syncLocks = { }
}

local os = _G.os

function Sync.sync(obj, fn)
  local key = tostring(obj)
  if Sync.syncLocks[key] then
    local cos = tostring(coroutine.running())
    table.insert(Sync.syncLocks[key], cos)
    repeat
      local _, co = os.pullEvent('sync_lock')
    until co == cos
  else
    Sync.syncLocks[key] = { }
  end
  local s, m = pcall(fn)
  local co = table.remove(Sync.syncLocks[key], 1)
  if co then
    os.queueEvent('sync_lock', co)
  else
    Sync.syncLocks[key] = nil
  end
  if not s then
    error(m)
  end
end

function Sync.lock(obj)
  local key = tostring(obj)
  if Sync.syncLocks[key] then
    local cos = tostring(coroutine.running())
    table.insert(Sync.syncLocks[key], cos)
    repeat
      local _, co = os.pullEvent('sync_lock')
    until co == cos
  else
    Sync.syncLocks[key] = { }
  end
end

function Sync.release(obj)
  local key = tostring(obj)
  if not Sync.syncLocks[key] then
    error('Sync.release: Lock was not obtained', 2)
  end
  local co = table.remove(Sync.syncLocks[key], 1)
  if co then
    os.queueEvent('sync_lock', co)
  else
    Sync.syncLocks[key] = nil
  end
end

function Sync.isLocked(obj)
  local key = tostring(obj)
  return not not Sync.syncLocks[key]
end

return Sync