Add graceful shutdown example (#84)

Author: andreiavrammsd

.gitignore

@@ -3,3 +3,4 @@
 install
 docs
 .cache
+*.profraw

Makefile

@@ -7,6 +7,7 @@ DOCS_DIR = docs
 all:
 
 bench:
+	# If needed: sudo cpupower frequency-set --governor <performance|powersave>
 	mkdir -p $(BENCH_DIR) && cd $(BENCH_DIR) \
 	&& cmake ../.. -DCMAKE_BUILD_TYPE=Release -DCPP_CHANNEL_BUILD_BENCHMARKS=ON \
 	&& cmake --build . --config Release --target channel_benchmark -j \

examples/CMakeLists.txt

@@ -37,3 +37,5 @@ run_example(example_concurrent_map_filter)
 
 add_example(example_semaphore semaphore.cpp)
 run_example(example_semaphore)
+
+add_example(example_graceful_shutdown graceful_shutdown.cpp)

examples/graceful_shutdown.cpp

@@ -0,0 +1,60 @@
+#include <msd/channel.hpp>
+
+#include <atomic>
+#include <chrono>
+#include <csignal>
+#include <future>
+#include <iostream>
+#include <sstream>
+#include <thread>
+
+static std::atomic<bool> shutdown{false};
+
+void handle_sigint(int)
+{
+    std::cout << "Waiting for channel to drain...\n";
+    shutdown.store(true, std::memory_order_seq_cst);
+}
+
+// Graceful shutdown using a bounded thread-safe channel. It runs a producer that sends integers and a consumer that
+// processes them. On Ctrl+C, it stops producing, closes the channel, and waits for the consumer to drain remaining
+// messages before exiting.
+
+int main()
+{
+    std::signal(SIGINT, handle_sigint);
+
+    msd::channel<int> channel{10};
+
+    // Continuously read from channel until it's drained (closed and empty)
+    const auto consume = [&channel]() {
+        for (const int message : channel) {
+            std::stringstream stream;
+            stream << message << " (" << channel.size() << ")\n";
+
+            std::cout << stream.str();
+
+            std::this_thread::sleep_for(std::chrono::milliseconds{100});
+        }
+    };
+
+    const auto consumer = std::async(consume);
+
+    // Continuously write to channel until process shutdown is requested
+    const auto produce = [&channel]() {
+        static int inc = 0;
+
+        while (!shutdown.load(std::memory_order_seq_cst)) {
+            ++inc;
+            channel << inc;
+        }
+
+        channel.close();
+    };
+
+    const auto producer = std::async(produce);
+
+    // Wait
+    consumer.wait();
+    producer.wait();
+}