SERVER-67602: Create Base Classes for Targeter and RetryPolicy

3 files changed, 184 insertions, 0 deletions

diff --git a/src/mongo/executor/remote_command_retry_policy.h b/src/mongo/executor/remote_command_retry_policy.h
new file mode 100644
index 00000000000..ea0d09613c8
--- /dev/null
+++ b/src/mongo/executor/remote_command_retry_policy.h
@@ -0,0 +1,77 @@
+/**
+ *    Copyright (C) 2022-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.
+ */
+
+#pragma once
+
+#include "mongo/base/status.h"
+#include "mongo/bson/bsonobj.h"
+#include "mongo/executor/remote_command_request.h"
+#include "mongo/util/duration.h"
+#include "mongo/util/time_support.h"
+#include <string>
+
+namespace mongo {
+namespace executor {
+namespace remote_command_runner {
+
+class RemoteCommandRetryPolicy {
+public:
+    /**
+     * Given an error, returns true if the scheduler should retry the remote command.
+     */
+    virtual bool shouldRetry(Status s) const = 0;
+
+    /**
+     * Retry scheduler should wait this long in between retrying remote commands.
+     */
+    virtual Milliseconds getNextRetryDelay() = 0;
+
+    virtual BSONObj toBSON() const = 0;
+
+    virtual ~RemoteCommandRetryPolicy() = default;
+};
+
+class RemoteCommandNoRetryPolicy : public RemoteCommandRetryPolicy {
+public:
+    bool shouldRetry(Status s) const override final {
+        return false;
+    }
+
+    Milliseconds getNextRetryDelay() override final {
+        return Milliseconds::zero();
+    }
+
+    BSONObj toBSON() const override final {
+        return BSON("retryPolicyType"
+                    << "NoRetryPolicy");
+    }
+};
+}  // namespace remote_command_runner
+}  // namespace executor
+}  // namespace mongo
diff --git a/src/mongo/executor/remote_command_runner_test.cpp b/src/mongo/executor/remote_command_runner_test.cpp
index 2534c3f949e..2623db371af 100644
--- a/src/mongo/executor/remote_command_runner_test.cpp
+++ b/src/mongo/executor/remote_command_runner_test.cpp
@@ -27,7 +27,9 @@
  *    it in the license file.
  */
 
+#include "mongo/executor/remote_command_retry_policy.h"
 #include "mongo/executor/remote_command_runner.h"
+#include "mongo/executor/remote_command_targeter.h"
 
 #include "mongo/bson/oid.h"
 #include "mongo/db/repl/hello_gen.h"
@@ -39,6 +41,7 @@
 #include "mongo/rpc/topology_version_gen.h"
 #include "mongo/unittest/bson_test_util.h"
 #include "mongo/unittest/unittest.h"
+#include "mongo/util/duration.h"
 #include "mongo/util/future.h"
 #include <memory>
 
@@ -196,6 +199,28 @@ TEST_F(RemoteCommandRunnerTestFixture, WriteError) {
     ASSERT_THROWS_CODE(resultFuture.get(), DBException, ErrorCodes::DocumentValidationFailure);
 }
 
+/*
+ * Basic Targeter that returns the host that invoked it.
+ */
+TEST_F(RemoteCommandRunnerTestFixture, LocalTargeter) {
+    RemoteCommandLocalHostTargeter t;
+    auto targetFuture = t.resolve(_cancellationToken);
+    auto target = targetFuture.get();
+
+    ASSERT_EQ(target.size(), 1);
+    ASSERT_EQ(HostAndPort("localhost", serverGlobalParams.port), target[0]);
+}
+
+/*
+ * Basic RetryPolicy that never retries.
+ */
+TEST_F(RemoteCommandRunnerTestFixture, NoRetry) {
+    RemoteCommandNoRetryPolicy p;
+
+    ASSERT_FALSE(p.shouldRetry(Status(ErrorCodes::BadValue, "mock")));
+    ASSERT_EQUALS(p.getNextRetryDelay(), Milliseconds::zero());
+}
+
 }  // namespace
 }  // namespace remote_command_runner
 }  // namespace executor
diff --git a/src/mongo/executor/remote_command_targeter.h b/src/mongo/executor/remote_command_targeter.h
new file mode 100644
index 00000000000..2af287d6c8e
--- /dev/null
+++ b/src/mongo/executor/remote_command_targeter.h
@@ -0,0 +1,82 @@
+/**
+ *    Copyright (C) 2022-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.
+ */
+
+#pragma once
+
+#include "mongo/base/status.h"
+#include "mongo/client/read_preference.h"
+#include "mongo/db/auth/validated_tenancy_scope.h"
+#include "mongo/db/operation_context.h"
+#include "mongo/db/server_options.h"
+#include "mongo/util/assert_util.h"
+#include "mongo/util/cancellation.h"
+#include "mongo/util/future.h"
+#include "mongo/util/net/hostandport.h"
+#include <vector>
+
+namespace mongo {
+namespace executor {
+namespace remote_command_runner {
+
+class RemoteCommandHostTargeter {
+public:
+    RemoteCommandHostTargeter() = default;
+
+    virtual ~RemoteCommandHostTargeter() = default;
+
+    /*
+     * Returns a collection of possible Hosts on which the command may run based on the specific
+     * settings (ReadPreference, etc.) of the targeter.
+     */
+    virtual SemiFuture<std::vector<HostAndPort>> resolve(CancellationToken t) = 0;
+
+    /*
+     * Informs the RemoteHostTargeter that an error happened when trying to run a command on a
+     * HostAndPort. Allows the targeter to update its view of the cluster's topology if network
+     * or shutdown errors are recieved.
+     */
+    virtual void onRemoteCommandError(HostAndPort h, Status s) = 0;
+};
+
+class RemoteCommandLocalHostTargeter : public RemoteCommandHostTargeter {
+public:
+    RemoteCommandLocalHostTargeter() = default;
+
+    SemiFuture<std::vector<HostAndPort>> resolve(CancellationToken t) override final {
+        HostAndPort h = HostAndPort("localhost", serverGlobalParams.port);
+        std::vector<HostAndPort> hostList{h};
+
+        return SemiFuture<std::vector<HostAndPort>>::makeReady(hostList);
+    }
+
+    void onRemoteCommandError(HostAndPort h, Status s) override final {}
+};
+}  // namespace remote_command_runner
+}  // namespace executor
+}  // namespace mongo