--
-- This file is part of lem-postgres.
-- Copyright 2011 Emil Renner Berthing
-- Copyright 2020 Asbjørn Sloth Tønnesen
--
-- lem-postgres is free software: you can redistribute it and/or
-- modify it under the terms of the GNU General Public License as
-- published by the Free Software Foundation, either version 3 of
-- the License, or (at your option) any later version.
--
-- lem-postgres is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-- GNU General Public License for more details.
--
-- You should have received a copy of the GNU General Public License
-- along with lem-postgres. If not, see <http://www.gnu.org/licenses/>.
--

local utils    = require 'lem.utils'
local postgres = require 'lem.postgres'

local remove = table.remove
local thisthread, suspend, resume = utils.thisthread, utils.suspend, utils.resume

local Connection = postgres.Connection

local QConnection = {}
QConnection.__index = QConnection

function QConnection:set_notifier(cb)
	Connection.set_notifier(self.conn, cb)
end

local function cancel_all(t)
	for i = 1, t.n - 1 do
		resume(t[i])
		t[i] = nil
	end
end

function QConnection:close()
	local ok, err = self.conn:close()
	cancel_all(self)
	return ok, err
end

function QConnection:__gc()
	cancel_all(self)
	self.conn = nil
end

local function lock(self)
	local n = self.n
	if n == 0 then
		self.n = 1
	else
		self[n] = thisthread()
		self.n = n + 1
		suspend()
	end
	return self.conn
end
QConnection.lock = lock

local function unlock(self, ...)
	local n = self.n - 1
	self.n = n
	if n > 0 then
		resume(remove(self, 1))
	end
	return ...
end
QConnection.unlock = unlock

local function wrap(method)
	return function(self, ...)
		return unlock(self, method(lock(self), ...))
	end
end

QConnection.exec    = wrap(Connection.exec)
QConnection.prepare = wrap(Connection.prepare)
QConnection.run     = wrap(Connection.run)

local qconnect
do
	local setmetatable = setmetatable
	local connect = postgres.connect

	function qconnect(...)
		local conn, err = connect(...)
		if not conn then return nil, err end

		return setmetatable({
			n = 0,
			conn = conn,
		}, QConnection)
	end
end

return {
	QConnection = QConnection,
	connect = qconnect,
}

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