[resty.concurrent] safe task executor

http://ruby-concurrency.github.io/concurrent-ruby/Concurrent/SafeTaskExecutor.html

gateway/src/resty/concurrent/safe_task_executor.lua

@@ -0,0 +1,37 @@
+local setmetatable = setmetatable
+local tab_remove = table.remove
+local pcall = pcall
+
+--- @class SafeTaskExecutor
+local _M = { }
+local instance = setmetatable({ }, { __index = _M })
+
+local mt = { __index = instance }
+
+--- @param task fun(...):any
+--- @return SafeTaskExecutor
+function _M.new(task)
+    return setmetatable({ task = task }, mt)
+end
+
+function _M.execute(task, ...)
+    return _M.new(task):execute(...)
+end
+
+--- @return boolean, any, any|string
+function instance:execute(...)
+    local task = self and self.task
+
+    if not task then return nil, 'not initialized' end
+
+    local ret = { pcall(task, ...) }
+    local ok = tab_remove(ret, 1)
+
+    if ok then
+        return true, ret
+    else
+        return false, nil, ret[1]
+    end
+end
+
+return _M

spec/resty/concurrent/safe_task_executor_spec.lua

@@ -0,0 +1,24 @@
+local SafeTaskExecutor = require('resty.concurrent.safe_task_executor')
+
+describe('SafeTaskExecutor', function()
+    it('has module level execute', function()
+        local task = spy.new(function () end)
+
+        SafeTaskExecutor.execute(task)
+
+        assert.spy(task).was_called(1)
+    end)
+
+    it('returns success', function()
+        local task = SafeTaskExecutor.new(function () return 'some value', 'some other value' end)
+
+        assert.same({true, { 'some value', 'some other value' }}, { task:execute() })
+    end)
+
+    it('returns failure', function ()
+        local task = SafeTaskExecutor.new(function () return error('some error') end)
+
+        assert.same({false, nil, 'some error'}, { task:execute() })
+    end)
+
+end)