Added callbacks for node errors and fifo overflow

Add new doc system which should/might deploy to pages.

tests/test_pool_node.cpp

@@ -4,6 +4,7 @@
 #include <kpn/interrupt_node.hpp>
 #include <atomic>
 #include <chrono>
+#include <mutex>
 #include <thread>
 
 using namespace kpn;
@@ -239,3 +240,225 @@ TEST_CASE("interrupt node: trigger after stop is ignored", "[interrupt_node]") {
     REQUIRE(out_ch.approx_size() == 0);
     pool->stop();
 }
+
+// ── Overflow callback ─────────────────────────────────────────────────────────
+
+TEST_CASE("pool node overflow callback fires on full output channel", "[pool_node][overflow]") {
+    auto pool = std::make_shared<ThreadPool>(2);
+    pool->start();
+
+    auto node = make_pool_node<double_it>(pool);
+    // Pre-fill a tiny channel so every node push overflows.
+    Channel<int> full_ch(1);
+    full_ch.push(99);
+    node.set_output_channel<0>(&full_ch);
+
+    std::atomic<int> overflow_count{0};
+    node.set_overflow_callback([&](auto) { overflow_count.fetch_add(1); });
+
+    node.start();
+    node.input_channel<0>().push(1);
+    node.input_channel<0>().push(2);
+
+    std::this_thread::sleep_for(std::chrono::milliseconds(50));
+    node.stop();
+    pool->stop();
+
+    REQUIRE(overflow_count.load() > 0);
+}
+
+TEST_CASE("pool node overflow callback is independent per instance", "[pool_node][overflow]") {
+    auto pool = std::make_shared<ThreadPool>(2);
+    pool->start();
+
+    auto nodeA = make_pool_node<double_it>(pool);
+    auto nodeB = make_pool_node<double_it>(pool);
+
+    std::atomic<int> a_overflows{0}, b_overflows{0};
+    nodeA.set_overflow_callback([&](auto) { a_overflows.fetch_add(1); });
+
+    Channel<int> full_ch(1);
+    full_ch.push(0);
+    nodeA.set_output_channel<0>(&full_ch);
+
+    Channel<int> ok_ch(20);
+    nodeB.set_output_channel<0>(&ok_ch);
+
+    nodeA.start();
+    nodeB.start();
+
+    nodeA.input_channel<0>().push(1);
+    nodeA.input_channel<0>().push(2);
+    nodeB.input_channel<0>().push(10);
+
+    std::this_thread::sleep_for(std::chrono::milliseconds(50));
+    nodeA.stop();
+    nodeB.stop();
+    pool->stop();
+
+    REQUIRE(a_overflows.load() > 0);
+    REQUIRE(b_overflows.load() == 0);
+}
+
+TEST_CASE("interrupt node overflow callback fires on full output", "[interrupt_node][overflow]") {
+    auto pool = std::make_shared<ThreadPool>(2);
+    pool->start();
+
+    g_interrupt_counter.store(0);
+    auto node = make_interrupt_node<interrupt_produce>(pool, out<>{});
+
+    Channel<int> full_ch(1);
+    full_ch.push(99);
+    node.set_output_channel<0>(&full_ch);
+
+    std::atomic<int> overflow_count{0};
+    node.set_overflow_callback([&](auto) { overflow_count.fetch_add(1); });
+
+    node.start();
+    auto trigger = node.get_trigger();
+    trigger(); trigger(); trigger();
+
+    std::this_thread::sleep_for(std::chrono::milliseconds(50));
+    node.stop();
+    pool->stop();
+
+    REQUIRE(overflow_count.load() > 0);
+}
+
+// ── self_stop: disable inputs + outputs on crash ──────────────────────────────
+
+static int always_throw(int) { throw std::runtime_error("node crashed"); return 0; }
+
+TEST_CASE("pool node self_stop disables output on crash so downstream sees closed", "[pool_node][self_stop]") {
+    auto pool = std::make_shared<ThreadPool>(2);
+    pool->start();
+
+    auto node = make_pool_node<always_throw>(pool, 5);
+    Channel<int> out_ch(10);
+    node.set_output_channel<0>(&out_ch);
+
+    node.start();
+    node.input_channel<0>().push(1);
+
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+
+    REQUIRE_FALSE(out_ch.is_accepting());
+
+    node.stop();
+    pool->stop();
+}
+
+TEST_CASE("pool node self_stop disables input on crash", "[pool_node][self_stop]") {
+    auto pool = std::make_shared<ThreadPool>(2);
+    pool->start();
+
+    auto node = make_pool_node<always_throw>(pool, 5);
+    Channel<int> out_ch(5);
+    node.set_output_channel<0>(&out_ch);
+
+    node.start();
+    node.input_channel<0>().push(1);
+
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+
+    REQUIRE_FALSE(node.input_channel<0>().is_accepting());
+
+    node.stop();
+    pool->stop();
+}
+
+TEST_CASE("pool node closed callback fires on self_stop from crash", "[pool_node][self_stop]") {
+    auto pool = std::make_shared<ThreadPool>(2);
+    pool->start();
+
+    auto node = make_pool_node<always_throw>(pool, 5);
+    Channel<int> out_ch(5);
+    node.set_output_channel<0>(&out_ch);
+
+    std::atomic<bool> closed_fired{false};
+    node.set_closed_callback([&](auto) { closed_fired.store(true); });
+
+    node.start();
+    node.input_channel<0>().push(1);
+
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+
+    REQUIRE(closed_fired.load());
+
+    node.stop();
+    pool->stop();
+}
+
+// ── Network-level event callbacks ─────────────────────────────────────────────
+
+TEST_CASE("network_overflow_callback fires on overflow", "[pool_node][network]") {
+    auto pool = std::make_shared<ThreadPool>(2);
+    pool->start();
+
+    auto node = make_pool_node<double_it>(pool);
+
+    Channel<int> full_ch(1);
+    full_ch.push(0);
+    node.set_output_channel<0>(&full_ch);
+
+    std::atomic<int> net_overflows{0};
+    node.set_network_overflow_callback([&](auto) { net_overflows.fetch_add(1); });
+
+    node.start();
+    node.input_channel<0>().push(1);
+    node.input_channel<0>().push(2);
+
+    std::this_thread::sleep_for(std::chrono::milliseconds(50));
+    node.stop();
+    pool->stop();
+
+    REQUIRE(net_overflows.load() > 0);
+}
+
+TEST_CASE("network_closed_callback fires on crash", "[pool_node][network]") {
+    auto pool = std::make_shared<ThreadPool>(2);
+    pool->start();
+
+    auto node = make_pool_node<always_throw>(pool);
+    Channel<int> out_ch(5);
+    node.set_output_channel<0>(&out_ch);
+
+    std::atomic<bool> net_closed{false};
+    node.set_network_closed_callback([&](auto) { net_closed.store(true); });
+
+    node.start();
+    node.input_channel<0>().push(1);
+
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+
+    REQUIRE(net_closed.load());
+
+    node.stop();
+    pool->stop();
+}
+
+TEST_CASE("per-node and network overflow callbacks both fire independently", "[pool_node][network]") {
+    auto pool = std::make_shared<ThreadPool>(2);
+    pool->start();
+
+    auto node = make_pool_node<double_it>(pool);
+
+    Channel<int> full_ch(1);
+    full_ch.push(0);
+    node.set_output_channel<0>(&full_ch);
+
+    std::atomic<int> per_node{0}, network{0};
+    node.set_overflow_callback([&](auto) { per_node.fetch_add(1); });
+    node.set_network_overflow_callback([&](auto) { network.fetch_add(1); });
+
+    node.start();
+    node.input_channel<0>().push(1);
+    node.input_channel<0>().push(2);
+
+    std::this_thread::sleep_for(std::chrono::milliseconds(50));
+    node.stop();
+    pool->stop();
+
+    REQUIRE(per_node.load() > 0);
+    REQUIRE(network.load() > 0);
+}