From eec849f4b9048019d73260675d1ef2c74987d349 Mon Sep 17 00:00:00 2001
From: sergiu128 <sergiu@tungsten.computer>
Date: Mon, 21 Oct 2024 18:09:58 +0200
Subject: [PATCH] Add writer example

---
 examples/writer.cpp | 68 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 examples/writer.cpp

diff --git a/examples/writer.cpp b/examples/writer.cpp
new file mode 100644
index 0000000..0f4f31d
--- /dev/null
+++ b/examples/writer.cpp
@@ -0,0 +1,68 @@
+#include <algorithm>
+#include <chrono>
+#include <cstdlib>
+#include <cstring>
+#include <seqlock/seqlock.hpp>
+#include <seqlock/util.hpp>
+#include <thread>
+
+using namespace seqlock;               // NOLINT
+using namespace std::chrono_literals;  // NOLINT
+
+int main() {  // NOLINT
+    const char* filename = "/shmfiletest42";
+    const size_t filesize = util::GetPageSize();
+
+    util::SharedMemory shm{filename, filesize};
+    auto* region = util::Region<mode::SingleWriter, 4096>::Create(shm);
+
+    std::atomic<int> writer_state{0};  // 0: preparing 1: working 2: done
+
+    std::thread writer{[&] {
+        char from[4096];
+        memset(from, 0, 4096);
+
+        writer_state = 1;
+        for (int i = 0; i < 1024; i++) {
+            memset(from, i & 127, 4096);  // NOLINT
+            region->Store(from, 4096);
+            std::this_thread::sleep_for(1ms);
+        }
+
+        writer_state = 2;
+    }};
+
+    std::atomic_flag ok{};
+    ok.clear();
+    std::thread reader{[&] {
+        while (writer_state == 0) {
+            std::this_thread::sleep_for(10ms);
+        }
+
+        char to[4096];
+        memset(to, 0, 4096);
+        while (writer_state == 1) {
+            region->Load(to, 4096);
+            if (to[0] > 0) {
+                ok.test_and_set();
+                for (int i = 0; i < 4095; i++) {
+                    if (to[i] != to[i + 1]) {
+                        std::cout << "invalid load" << std::endl;
+                        std::terminate();
+                    }
+                }
+            }
+        }
+    }};
+
+    writer.join();
+    reader.join();
+
+    if (not ok.test()) {
+        std::cout << "invalid load" << std::endl;
+        return EXIT_FAILURE;
+    }
+
+    std::cout << "load successful" << std::endl;
+    return EXIT_SUCCESS;
+}