# HG changeset patch
# User Kim Alvefur <zash@zash.se>
# Date 1637248903 -3600
# Node ID ff4e34c448a44d8bb6bc459f9a4c6e8ec80c43e8
# Parent  fae5441fc6cf4b1109d8cf9fd239424733911663
net.server_epoll: Try harder to avoid reentrant opportunistic writes

Opportunistic writes sure do complicate things. This is especially
intended to avoid opportunistic_writes from within the onpredrain
callback.

diff -r fae5441fc6cf -r ff4e34c448a4 net/server_epoll.lua
--- a/net/server_epoll.lua	Thu Nov 18 01:57:21 2021 +0100
+++ b/net/server_epoll.lua	Thu Nov 18 16:21:43 2021 +0100
@@ -487,6 +487,7 @@
 
 -- Called when socket is writable
 function interface:onwritable()
+	self._writing = true; -- prevent reentrant writes etc
 	self:onconnect();
 	if not self.conn then return; end -- could have been closed in onconnect
 	self:on("predrain");
@@ -514,6 +515,7 @@
 		end
 		self:setwritetimeout(false);
 		self:ondrain(); -- Be aware of writes in ondrain
+		self._writing = nil;
 		return ok;
 	elseif partial then
 		self:debug("Sent %d out of %d buffered bytes", partial, #data);
@@ -528,6 +530,7 @@
 		self:set(nil, true);
 		self:setwritetimeout();
 	end
+	self._writing = nil;
 	if err == "wantwrite" or err == "timeout" then
 		self:set(nil, true);
 		self:setwritetimeout();
@@ -557,7 +560,7 @@
 	elseif buffer == nil then
 		self.writebuffer = data;
 	end
-	if not self._write_lock then
+	if not self._write_lock and not self._writing then
 		if self._writable and cfg.opportunistic_writes and not self._opportunistic_write then
 			self._opportunistic_write = true;
 			local ret, err = self:onwritable();