From 73dfbeb1d59fbc1e22651cb4da8ee85f0a6fd9ce Mon Sep 17 00:00:00 2001
From: Eric Wong <normalperson@yhbt.net>
Date: Tue, 3 Jul 2012 17:57:44 -0700
Subject: blocking functions do not raise Errno::EINTR

Blocking functions should not raise Errno::EINTR to match
existing semantics of Ruby IO methods (e.g. IO.select, IO#read,
IO#write).  This makes user code easier to read/write.

Like th Ruby methods we emulate, we only reacquire the GVL on
EINTR to fire signal handlers, but otherwise emulate SA_RESTART
semantics.

This is a backwards-incompatible API change (but unlikely
to break existing code).
---
 ext/posix_mq/posix_mq.c | 12 +++++++++++-
 test/test_posix_mq.rb   | 10 ++++++----
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/ext/posix_mq/posix_mq.c b/ext/posix_mq/posix_mq.c
index 2958352..df667e3 100644
--- a/ext/posix_mq/posix_mq.c
+++ b/ext/posix_mq/posix_mq.c
@@ -542,8 +542,11 @@ static VALUE _send(int sflags, int argc, VALUE *argv, VALUE self)
 	x.timeout = convert_timeout(&expire, timeout);
 	x.msg_prio = NIL_P(prio) ? 0 : NUM2UINT(prio);
 
+retry:
 	rv = (mqd_t)rb_thread_blocking_region(xsend, &x, RUBY_UBF_IO, 0);
 	if (rv == MQD_INVALID) {
+		if (errno == EINTR)
+			goto retry;
 		if (errno == EAGAIN && (sflags & PMQ_TRY))
 			return Qfalse;
 		rb_sys_fail("mq_send");
@@ -574,9 +577,13 @@ static VALUE send0(VALUE self, VALUE buffer)
 	x.timeout = NULL;
 	x.msg_prio = 0;
 
+retry:
 	rv = (mqd_t)rb_thread_blocking_region(xsend, &x, RUBY_UBF_IO, 0);
-	if (rv == MQD_INVALID)
+	if (rv == MQD_INVALID) {
+		if (errno == EINTR)
+			goto retry;
 		rb_sys_fail("mq_send");
+	}
 
 	return self;
 }
@@ -678,8 +685,11 @@ static VALUE _receive(int rflags, int argc, VALUE *argv, VALUE self)
 	x.msg_len = (size_t)mq->attr.mq_msgsize;
 	x.des = mq->des;
 
+retry:
 	r = (ssize_t)rb_thread_blocking_region(xrecv, &x, RUBY_UBF_IO, 0);
 	if (r < 0) {
+		if (errno == EINTR)
+			goto retry;
 		if (errno == EAGAIN && (rflags & PMQ_TRY))
 			return Qnil;
 		rb_sys_fail("mq_receive");
diff --git a/test/test_posix_mq.rb b/test/test_posix_mq.rb
index 5b78c22..8d6b014 100644
--- a/test/test_posix_mq.rb
+++ b/test/test_posix_mq.rb
@@ -118,16 +118,18 @@ class Test_POSIX_MQ < Test::Unit::TestCase
     end
     alarm or return warn "alarm() not found in #{libcs.inspect}"
     alarms = 0
-    trap("ALRM") { alarms += 1 }
+    trap("ALRM") do
+      alarms += 1
+      Thread.new { @mq.send("HI") }
+    end
     interval = 1
     alarm.call interval
     @mq = POSIX_MQ.new(@path, :rw)
     assert ! @mq.nonblock?
     t0 = Time.now
-    a = nil
-    assert_raises(Errno::EINTR) { a = @mq.receive }
+    a = @mq.receive
     elapsed = Time.now - t0
-    assert_nil a
+    assert_equal(["HI", 0], a)
     assert elapsed >= interval, elapsed.inspect
     assert elapsed < 1.10, elapsed.inspect
     assert_equal 1, alarms
-- 
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