SERVER-45521 Define TopologyListener, ServerPingMonitor, and SingleServerPingMonitor classes.

 create mode 100644 src/mongo/client/sdam/topology_listener.h
 create mode 100644 src/mongo/client/server_ping_monitor.cpp
 create mode 100644 src/mongo/client/server_ping_monitor.h

1 files changed, 101 insertions, 0 deletions

diff --git a/src/mongo/client/server_ping_monitor.cpp b/src/mongo/client/server_ping_monitor.cpp
new file mode 100644
index 00000000000..2e2e8bf2e43
--- /dev/null
+++ b/src/mongo/client/server_ping_monitor.cpp
@@ -0,0 +1,101 @@
+/**
+ *    Copyright (C) 2020-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kNetwork
+#include "mongo/client/server_ping_monitor.h"
+
+#include "mongo/executor/network_interface_factory.h"
+#include "mongo/executor/network_interface_thread_pool.h"
+#include "mongo/executor/thread_pool_task_executor.h"
+#include "mongo/rpc/metadata/egress_metadata_hook_list.h"
+#include "mongo/util/log.h"
+
+namespace mongo {
+
+using executor::NetworkInterface;
+using executor::NetworkInterfaceThreadPool;
+using executor::TaskExecutor;
+using executor::ThreadPoolTaskExecutor;
+
+SingleServerPingMonitor::SingleServerPingMonitor(sdam::ServerAddress hostAndPort,
+                                                 sdam::TopologyListener* rttListener,
+                                                 Seconds pingFrequency,
+                                                 std::shared_ptr<TaskExecutor> executor)
+    : _hostAndPort(hostAndPort),
+      _rttListener(rttListener),
+      _pingFrequency(pingFrequency),
+      _executor(executor) {}
+
+void SingleServerPingMonitor::drop() { /** TODO SERVER-45051: Implement drop() functionality. **/
+}
+
+ServerPingMonitor::ServerPingMonitor(sdam::TopologyListener* rttListener,
+                                     Seconds pingFrequency,
+                                     boost::optional<std::shared_ptr<TaskExecutor>> executor)
+    : _rttListener(rttListener), _pingFrequency(pingFrequency) {
+    // Create an executor by default. Don't create an executor if one was passed in for testing.
+    _setupTaskExecutor(executor);
+}
+
+void ServerPingMonitor::_setupTaskExecutor(
+    boost::optional<std::shared_ptr<TaskExecutor>> executor) {
+    if (executor) {
+        // An executor was already provided for testing.
+        _executor = std::move(executor.value());
+    } else {
+        auto hookList = std::make_unique<rpc::EgressMetadataHookList>();
+        auto net = executor::makeNetworkInterface(
+            "ServerPingMonitor-TaskExecutor", nullptr, std::move(hookList));
+        auto pool = std::make_unique<NetworkInterfaceThreadPool>(net.get());
+        _executor = std::make_shared<ThreadPoolTaskExecutor>(std::move(pool), std::move(net));
+    }
+    _executor->startup();
+}
+
+void ServerPingMonitor::onServerHandshakeCompleteEvent(sdam::ServerAddress address,
+                                                       OID topologyId) {
+    stdx::lock_guard lk(_mutex);
+    invariant(_serverPingMonitorMap.find(address) == _serverPingMonitorMap.end());
+    _serverPingMonitorMap.emplace(address,
+                                  std::make_unique<SingleServerPingMonitor>(
+                                      address, _rttListener, _pingFrequency, _executor));
+    LOG(1) << "ServerPingMonitor is now monitoring " << address;
+}
+
+void ServerPingMonitor::onServerClosedEvent(sdam::ServerAddress address, OID topologyId) {
+    stdx::lock_guard lk(_mutex);
+    auto it = _serverPingMonitorMap.find(address);
+    invariant(it != _serverPingMonitorMap.end());
+    it->second->drop();
+    _serverPingMonitorMap.erase(it);
+    LOG(1) << "ServerPingMonitor stopped  monitoring " << address;
+}
+
+
+}  // namespace mongo