From 12e45b843432de4c58e6dc3662d4478a4f0ed014 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Henrik=20Grubbstr=C3=B6m=20=28Grubba=29?=
<grubba@grubba.org>
Date: Mon, 26 Oct 2020 11:52:21 +0100
Subject: [PATCH] Concurrent.Promise: Fixed race-condition in finalise().
The API for finalise() raced with on_{success,failure}(), as
new callbacks could get registered after finalise() was called,
but before the state was updated.
Fixes #10055.
---
lib/modules/Concurrent.pmod | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/lib/modules/Concurrent.pmod b/lib/modules/Concurrent.pmod
index 6304cbb11b..c5fb0362c1 100644
--- a/lib/modules/Concurrent.pmod
+++ b/lib/modules/Concurrent.pmod
@@ -232,6 +232,7 @@ class Future
//! @[on_failure()], @[query_success_callbacks()]
this_program on_success(function(mixed, mixed ... : void) cb, mixed ... extra)
{
+ Thread.MutexKey key = mux->lock();
switch (state) {
case STATE_FULFILLED:
call_callback(cb, result, @extra);
@@ -274,6 +275,7 @@ class Future
//! @[on_success()], @[query_failure_callbacks()]
this_program on_failure(function(mixed, mixed ... : void) cb, mixed ... extra)
{
+ Thread.MutexKey key = mux->lock();
switch (state) {
case STATE_REJECTED:
state = STATE_REJECTION_REPORTED;
@@ -941,14 +943,19 @@ class Promise
return Future::this;
}
- protected this_program finalise(State newstate, mixed value, int try,
- array(array(function(mixed, mixed ...: void)|array(mixed))) cbs)
+ protected this_program finalise(State newstate, mixed value, int try)
{
Thread.MutexKey key = mux->lock();
if (state <= STATE_PENDING)
{
state = newstate;
result = value;
+ array(array(function(mixed, mixed ...: void)|array(mixed))) cbs;
+ if (state == STATE_FULFILLED) {
+ cbs = success_cbs;
+ } else {
+ cbs = failure_cbs;
+ }
key = 0;
cond->broadcast();
if (sizeof(cbs))
@@ -989,7 +996,7 @@ class Promise
//! @[try_success()], @[try_failure()], @[failure()], @[on_success()]
this_program success(mixed value, void|int try)
{
- return finalise(STATE_FULFILLED, value, try, success_cbs);
+ return finalise(STATE_FULFILLED, value, try);
}
//! Fulfill the @[Future] if it hasn't been fulfilled or failed already.
@@ -1027,7 +1034,7 @@ class Promise
this_program failure(mixed value, void|int try)
{
return
- finalise(STATE_REJECTED, value, try, failure_cbs);
+ finalise(STATE_REJECTED, value, try);
}
//! Maybe reject the @[Future] value.
--
GitLab