commit f74daa655799a7ad01e090b658b0c8600f98f814
author Austin Schuh <austin.schuh@bluerivertech.com> Wed Jul 21 15:29:17 2021 -0700
committer Austin Schuh <austin.schuh@bluerivertech.com> Wed Jul 21 15:29:17 2021 -0700
tree af8d060fd6f6e695bb61105325ac40b853a29921
parent 479933181ebdc39b6c41cf567d4cb52393ebeffd

Make EPoll actually return from Run even if you call Quit repeatedly

This comes up for integrating external event loops.

Change-Id: Icf8c9cbb7ee0c9ac5d677ab0445a8966d94f2708
Signed-off-by: Austin Schuh <austin.schuh@bluerivertech.com>

aos/events/epoll.cc

diff --git a/aos/events/epoll.cc b/aos/events/epoll.cc
index 1c4427b..7fff6ef 100644
--- a/aos/events/epoll.cc
+++ b/aos/events/epoll.cc
@@ -127,7 +127,14 @@
   return true;
 }
 
-void EPoll::Quit() { PCHECK(write(quit_signal_fd_, "q", 1) == 1); }
+void EPoll::Quit() {
+  // Shortcut to break us out of infinite loops. We might write more than once
+  // to the pipe, but we'll stop once the first is read on the other end.
+  if (!run_) {
+    return;
+  }
+  PCHECK(write(quit_signal_fd_, "q", 1) == 1);
+}
 
 void EPoll::OnReadable(int fd, ::std::function<void()> function) {
   EventData *event_data = GetEventData(fd);

aos/events/epoll_test.cc

diff --git a/aos/events/epoll_test.cc b/aos/events/epoll_test.cc
index 66460c2..053a09b 100644
--- a/aos/events/epoll_test.cc
+++ b/aos/events/epoll_test.cc
@@ -3,8 +3,8 @@
 #include <fcntl.h>
 #include <unistd.h>
 
-#include "gtest/gtest.h"
 #include "glog/logging.h"
+#include "gtest/gtest.h"
 
 namespace aos {
 namespace internal {
@@ -48,22 +48,22 @@
 };
 
 class EPollTest : public ::testing::Test {
-  public:
-   void RunFor(std::chrono::nanoseconds duration) {
-     TimerFd timerfd;
-     bool did_quit = false;
-     epoll_.OnReadable(timerfd.fd(), [this, &timerfd, &did_quit]() {
-       CHECK(!did_quit);
-       epoll_.Quit();
-       did_quit = true;
-       timerfd.Read();
-     });
-     timerfd.SetTime(monotonic_clock::now() + duration,
-                     monotonic_clock::duration::zero());
-     epoll_.Run();
-     CHECK(did_quit);
-     epoll_.DeleteFd(timerfd.fd());
-   }
+ public:
+  void RunFor(std::chrono::nanoseconds duration) {
+    TimerFd timerfd;
+    bool did_quit = false;
+    epoll_.OnReadable(timerfd.fd(), [this, &timerfd, &did_quit]() {
+      CHECK(!did_quit);
+      epoll_.Quit();
+      did_quit = true;
+      timerfd.Read();
+    });
+    timerfd.SetTime(monotonic_clock::now() + duration,
+                    monotonic_clock::duration::zero());
+    epoll_.Run();
+    CHECK(did_quit);
+    epoll_.DeleteFd(timerfd.fd());
+  }
 
   // Tests should avoid relying on ordering for events closer in time than this,
   // or waiting for longer than this to ensure events happen in order.
@@ -71,7 +71,7 @@
     return std::chrono::milliseconds(50);
   }
 
-   EPoll epoll_;
+  EPoll epoll_;
 };
 
 // Test that the basics of OnReadable work.
@@ -201,6 +201,11 @@
   epoll_.DeleteFd(pipe.write_fd());
 }
 
+TEST_F(EPollTest, QuitInBeforeWait) {
+  epoll_.BeforeWait([this]() { epoll_.Quit(); });
+  epoll_.Run();
+}
+
 }  // namespace testing
 }  // namespace internal
 }  // namespace aos