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authorVincent Ambo <tazjin@google.com>2020-05-17T14·52+0100
committerVincent Ambo <tazjin@google.com>2020-05-17T14·52+0100
commit7994fd1d545cc5c876d6f21db7ddf9185d23dad6 (patch)
tree32dd695785378c5b9c8be97fc583e9dfc62cb105 /third_party/nix/src/libutil/monitor-fd.hh
parentcf8cd640c1adf74a3706efbcb0ea4625da106fb2 (diff)
parent90b3b31dc27f31e9b11653a636025d29ddb087a3 (diff)
Add 'third_party/nix/' from commit 'be66c7a6b24e3c3c6157fd37b86c7203d14acf10' r/724
git-subtree-dir: third_party/nix
git-subtree-mainline: cf8cd640c1adf74a3706efbcb0ea4625da106fb2
git-subtree-split: be66c7a6b24e3c3c6157fd37b86c7203d14acf10
Diffstat (limited to 'third_party/nix/src/libutil/monitor-fd.hh')
-rw-r--r--third_party/nix/src/libutil/monitor-fd.hh58
1 files changed, 58 insertions, 0 deletions
diff --git a/third_party/nix/src/libutil/monitor-fd.hh b/third_party/nix/src/libutil/monitor-fd.hh
new file mode 100644
index 000000000000..5ee0b88ef50f
--- /dev/null
+++ b/third_party/nix/src/libutil/monitor-fd.hh
@@ -0,0 +1,58 @@
+#pragma once
+
+#include <thread>
+#include <atomic>
+
+#include <cstdlib>
+#include <poll.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <signal.h>
+
+namespace nix {
+
+
+class MonitorFdHup
+{
+private:
+    std::thread thread;
+
+public:
+    MonitorFdHup(int fd)
+    {
+        thread = std::thread([fd]() {
+            while (true) {
+              /* Wait indefinitely until a POLLHUP occurs. */
+              struct pollfd fds[1];
+              fds[0].fd = fd;
+              /* This shouldn't be necessary, but macOS doesn't seem to
+                 like a zeroed out events field.
+                 See rdar://37537852.
+              */
+              fds[0].events = POLLHUP;
+              auto count = poll(fds, 1, -1);
+              if (count == -1) abort(); // can't happen
+              /* This shouldn't happen, but can on macOS due to a bug.
+                 See rdar://37550628.
+
+                 This may eventually need a delay or further
+                 coordination with the main thread if spinning proves
+                 too harmful.
+               */
+              if (count == 0) continue;
+              assert(fds[0].revents & POLLHUP);
+              triggerInterrupt();
+              break;
+            }
+        });
+    };
+
+    ~MonitorFdHup()
+    {
+        pthread_cancel(thread.native_handle());
+        thread.join();
+    }
+};
+
+
+}