From 79fda9ada7878afef263f4786fd3967ec6dbfdc7 Mon Sep 17 00:00:00 2001
From: Yuqian Yang <crupest@crupest.life>
Date: Fri, 5 Sep 2025 22:08:42 +0800
Subject: Add ReadTimerPipe.

---
 include/cru/base/platform/unix/EventLoop.h |  8 ++++++++
 include/cru/base/platform/unix/UnixFile.h  |  3 +++
 src/base/platform/unix/EventLoop.cpp       | 32 ++++++++++++++++++++++++++++++
 3 files changed, 43 insertions(+)

diff --git a/include/cru/base/platform/unix/EventLoop.h b/include/cru/base/platform/unix/EventLoop.h
index bc2bcbf8..b735ef26 100644
--- a/include/cru/base/platform/unix/EventLoop.h
+++ b/include/cru/base/platform/unix/EventLoop.h
@@ -84,11 +84,19 @@ class UnixEventLoop : public Object2 {
           action(std::move(action)) {}
   };
 
+private:
+  bool ReadTimerPipe();
+
+private:  
+
   std::thread::id running_thread_;
 
   std::atomic_int timer_tag_;
   std::vector<TimerData> timers_;
 
+  UnixFileDescriptor timer_pipe_read_end_;
+  UnixFileDescriptor timer_pipe_write_end_;
+
   std::optional<int> exit_code_;
 };
 
diff --git a/include/cru/base/platform/unix/UnixFile.h b/include/cru/base/platform/unix/UnixFile.h
index 8ce3249d..a5f1eb81 100644
--- a/include/cru/base/platform/unix/UnixFile.h
+++ b/include/cru/base/platform/unix/UnixFile.h
@@ -37,6 +37,9 @@ class UnixFileDescriptor {
   explicit operator bool() const { return this->IsValid(); }
   operator int() const { return this->GetValue(); }
 
+  /**
+   * If O_NONBLOCK is set and EAGAIN or EWOULDBLOCK is returned, -1 is returned.
+   */
   ssize_t Read(void* buffer, size_t size);
   void SetFileDescriptorFlags(int flags);
 
diff --git a/src/base/platform/unix/EventLoop.cpp b/src/base/platform/unix/EventLoop.cpp
index 337d8a44..0aac4134 100644
--- a/src/base/platform/unix/EventLoop.cpp
+++ b/src/base/platform/unix/EventLoop.cpp
@@ -37,6 +37,10 @@ int UnixEventLoop::Run() {
       continue;
     }
 
+    while (ReadTimerPipe()) {
+      continue;
+    }
+
     if (!timers_.empty()) {
       poll_timeout =
           std::ranges::min_element(timers_, [](const TimerData &left,
@@ -89,4 +93,32 @@ int UnixEventLoop::SetTimer(std::function<void()> action,
   return tag;
 }
 
+bool UnixEventLoop::ReadTimerPipe() {
+  TimerData *pointer;
+  constexpr size_t pointer_size = sizeof(decltype(pointer));
+  auto rest = pointer_size;
+  while (true) {
+    auto result = timer_pipe_read_end_.Read(&pointer, rest);
+
+    if (result == -1) {  // If no data.
+      if (rest == pointer_size) {
+        return false;
+      } else {
+        continue;  // Try read again (might spin), as we are in the middle of
+                   // reading a pointer.
+      }
+    }
+
+    if (result == 0) {
+      throw Exception("Unexpected EOF of the timer pipe.");
+    }
+
+    rest -= result;
+  }
+
+  timers_.push_back(std::move(*pointer));
+  delete pointer;
+
+  return true;
+}
 }  // namespace cru::platform::unix
-- 
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