[Pkg-bitcoin-commits] [bitcoin] 116/126: rpc: work-around an upstream libevent bug
Jonas Smedegaard
dr at jones.dk
Mon Nov 13 20:03:01 UTC 2017
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js pushed a commit to annotated tag debian/0.15.1_dfsg-1
in repository bitcoin.
commit 34153a7e4a52be30582d96426e77a7a04e9721fb
Author: Cory Fields <cory-nospam- at coryfields.com>
Date: Wed Nov 1 12:02:57 2017 -0400
rpc: work-around an upstream libevent bug
A rare race condition may trigger while awaiting the body of a message, see
upsteam commit 5ff8eb26371c4dc56f384b2de35bea2d87814779 for details.
This may fix some reported rpc hangs/crashes.
Github-Pull: #11593
Rebased-From: 6b58360f9b64eb0b680a662fdfd590e47f115f44
---
src/httpserver.cpp | 32 ++++++++++++++++++++++++++++----
1 file changed, 28 insertions(+), 4 deletions(-)
diff --git a/src/httpserver.cpp b/src/httpserver.cpp
index 86b37f7..a3a9008 100644
--- a/src/httpserver.cpp
+++ b/src/httpserver.cpp
@@ -24,6 +24,7 @@
#include <event2/thread.h>
#include <event2/buffer.h>
+#include <event2/bufferevent.h>
#include <event2/util.h>
#include <event2/keyvalq_struct.h>
@@ -239,6 +240,16 @@ static std::string RequestMethodString(HTTPRequest::RequestMethod m)
/** HTTP request callback */
static void http_request_cb(struct evhttp_request* req, void* arg)
{
+ // Disable reading to work around a libevent bug, fixed in 2.2.0.
+ if (event_get_version_number() < 0x02020001) {
+ evhttp_connection* conn = evhttp_request_get_connection(req);
+ if (conn) {
+ bufferevent* bev = evhttp_connection_get_bufferevent(conn);
+ if (bev) {
+ bufferevent_disable(bev, EV_READ);
+ }
+ }
+ }
std::unique_ptr<HTTPRequest> hreq(new HTTPRequest(req));
LogPrint(BCLog::HTTP, "Received a %s request for %s from %s\n",
@@ -599,11 +610,24 @@ void HTTPRequest::WriteReply(int nStatus, const std::string& strReply)
struct evbuffer* evb = evhttp_request_get_output_buffer(req);
assert(evb);
evbuffer_add(evb, strReply.data(), strReply.size());
- HTTPEvent* ev = new HTTPEvent(eventBase, true,
- std::bind(evhttp_send_reply, req, nStatus, (const char*)nullptr, (struct evbuffer *)nullptr));
- ev->trigger(0);
+ auto req_copy = req;
+ HTTPEvent* ev = new HTTPEvent(eventBase, true, [req_copy, nStatus]{
+ evhttp_send_reply(req_copy, nStatus, nullptr, nullptr);
+ // Re-enable reading from the socket. This is the second part of the libevent
+ // workaround above.
+ if (event_get_version_number() < 0x02020001) {
+ evhttp_connection* conn = evhttp_request_get_connection(req_copy);
+ if (conn) {
+ bufferevent* bev = evhttp_connection_get_bufferevent(conn);
+ if (bev) {
+ bufferevent_enable(bev, EV_READ | EV_WRITE);
+ }
+ }
+ }
+ });
+ ev->trigger(nullptr);
replySent = true;
- req = 0; // transferred back to main thread
+ req = nullptr; // transferred back to main thread
}
CService HTTPRequest::GetPeer()
--
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