Used DB lock instead of Java lock

@@ -43,7 +43,6 @@ public class OAuth2Controller extends BaseController {
     @Autowired
     private OAuth2Service oauth2Service;
 
-    // TODO ask why POST
     @RequestMapping(value = "/noauth/oauth2Clients", method = RequestMethod.POST)
     @ResponseBody
     public List<OAuth2ClientInfo> getOAuth2Clients(HttpServletRequest request) throws ThingsboardException {

+/**
+ * Copyright © 2016-2020 The Thingsboard Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.thingsboard.server.dao.lock;
+
+public enum LockKey {
+    OAUTH2_CONFIG(999);
+
+    private int id;
+
+    LockKey(int id) {
+        this.id = id;
+    }
+
+    public int getId() {
+        return id;
+    }
+}

+/**
+ * Copyright © 2016-2020 The Thingsboard Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.thingsboard.server.dao.lock;
+
+public interface LockService {
+    /**
+     * Lock with SQL Database till the end of transaction
+     *
+     * @param key identifier
+     */
+    void transactionLock(LockKey key);
+}

+/**
+ * Copyright © 2016-2020 The Thingsboard Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.thingsboard.server.dao.lock;
+
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+import org.thingsboard.server.dao.sql.lock.LockRepository;
+
+import javax.annotation.PostConstruct;
+
+@Service
+@Slf4j
+public class LockServiceImpl implements LockService {
+
+    @Autowired(required = false)
+    private LockRepository lockRepository;
+
+    @PostConstruct
+    public void init(){
+        log.warn("Locking with DB is not enabled.");
+    }
+
+    @Override
+    public void transactionLock(LockKey key) {
+        if (lockRepository == null) return;
+        log.trace("Locking transaction key [{}]", key);
+        lockRepository.transactionLock(key.getId());
+    }
+}

 /**
  * Copyright © 2016-2020 The Thingsboard Authors
- * <p>
+ *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * <p>
- * http://www.apache.org/licenses/LICENSE-2.0
- * <p>
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -28,6 +28,7 @@ import org.apache.commons.lang3.tuple.Pair;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.core.env.Environment;
 import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
 import org.springframework.util.StringUtils;
 import org.thingsboard.server.common.data.*;
 import org.thingsboard.server.common.data.id.*;
@@ -36,13 +37,14 @@ import org.thingsboard.server.common.data.oauth2.*;
 import org.thingsboard.server.dao.attributes.AttributesService;
 import org.thingsboard.server.dao.exception.DataValidationException;
 import org.thingsboard.server.dao.exception.IncorrectParameterException;
+import org.thingsboard.server.dao.lock.LockKey;
+import org.thingsboard.server.dao.lock.LockService;
 import org.thingsboard.server.dao.settings.AdminSettingsService;
 import org.thingsboard.server.dao.tenant.TenantService;
 
 import java.io.IOException;
 import java.util.*;
 import java.util.concurrent.ExecutionException;
-import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Consumer;
 import java.util.stream.Collectors;
 
@@ -51,11 +53,8 @@ import static org.thingsboard.server.dao.oauth2.OAuth2Utils.*;
 @Slf4j
 @Service
 public class OAuth2ServiceImpl implements OAuth2Service {
-
     private static final ObjectMapper mapper = new ObjectMapper();
 
-    private final ReentrantLock clientRegistrationSaveLock = new ReentrantLock();
-
     @Autowired
     private Environment environment;
 
@@ -68,6 +67,9 @@ public class OAuth2ServiceImpl implements OAuth2Service {
     @Autowired
     private TenantService tenantService;
 
+    @Autowired
+    private LockService lockService;
+
     private boolean isInstall() {
         return environment.acceptsProfiles("install");
     }
@@ -123,52 +125,59 @@ public class OAuth2ServiceImpl implements OAuth2Service {
     @Override
     public OAuth2ClientsParams saveSystemOAuth2ClientsParams(OAuth2ClientsParams oAuth2ClientsParams) {
         validate(oAuth2ClientsParams);
-
         validateRegistrationIdUniqueness(oAuth2ClientsParams, TenantId.SYS_TENANT_ID);
-        clientRegistrationSaveLock.lock();
-        try {
-            validateRegistrationIdUniqueness(oAuth2ClientsParams, TenantId.SYS_TENANT_ID);
-            AdminSettings oauth2SystemAdminSettings = adminSettingsService.findAdminSettingsByKey(TenantId.SYS_TENANT_ID, OAUTH2_CLIENT_REGISTRATIONS_PARAMS);
-            if (oauth2SystemAdminSettings == null) {
-                oauth2SystemAdminSettings = createSystemAdminSettings();
-            }
-            String json = toJson(oAuth2ClientsParams);
-            ((ObjectNode) oauth2SystemAdminSettings.getJsonValue()).put(SYSTEM_SETTINGS_OAUTH2_VALUE, json);
-            adminSettingsService.saveAdminSettings(TenantId.SYS_TENANT_ID, oauth2SystemAdminSettings);
-        } finally {
-            clientRegistrationSaveLock.unlock();
-        }
+
+        transactionalSaveSystemOAuth2ClientsParams(oAuth2ClientsParams);
 
         return getSystemOAuth2ClientsParams();
     }
 
+    @Transactional
+    private void transactionalSaveSystemOAuth2ClientsParams(OAuth2ClientsParams oAuth2ClientsParams) {
+        long acquireStart = System.currentTimeMillis();
+        lockService.transactionLock(LockKey.OAUTH2_CONFIG);
+        log.trace("[{}] Waited for lock {} ms.", TenantId.SYS_TENANT_ID, System.currentTimeMillis() - acquireStart);
+
+        validateRegistrationIdUniqueness(oAuth2ClientsParams, TenantId.SYS_TENANT_ID);
+        AdminSettings oauth2SystemAdminSettings = adminSettingsService.findAdminSettingsByKey(TenantId.SYS_TENANT_ID, OAUTH2_CLIENT_REGISTRATIONS_PARAMS);
+        if (oauth2SystemAdminSettings == null) {
+            oauth2SystemAdminSettings = createSystemAdminSettings();
+        }
+        String json = toJson(oAuth2ClientsParams);
+        ((ObjectNode) oauth2SystemAdminSettings.getJsonValue()).put(SYSTEM_SETTINGS_OAUTH2_VALUE, json);
+        adminSettingsService.saveAdminSettings(TenantId.SYS_TENANT_ID, oauth2SystemAdminSettings);
+    }
+
     @Override
     public OAuth2ClientsParams saveTenantOAuth2ClientsParams(TenantId tenantId, OAuth2ClientsParams oAuth2ClientsParams) {
         validate(oAuth2ClientsParams);
-
         validateRegistrationIdUniqueness(oAuth2ClientsParams, tenantId);
-        clientRegistrationSaveLock.lock();
-        try {
-            validateRegistrationIdUniqueness(oAuth2ClientsParams, tenantId);
 
-            Set<String> domainNames = oAuth2ClientsParams.getClientsDomainsParams().stream()
-                    .map(OAuth2ClientsDomainParams::getDomainName)
-                    .collect(Collectors.toSet());
-            processTenantAdminSettings(tenantId, domainNames);
+        transactionalSaveTenantOAuth2ClientsParams(tenantId, oAuth2ClientsParams);
 
-            List<AttributeKvEntry> attributes = createOAuth2ClientsParamsAttributes(oAuth2ClientsParams);
-            try {
-                attributesService.save(tenantId, tenantId, DataConstants.SERVER_SCOPE, attributes).get();
-            } catch (Exception e) {
-                log.error("Unable to save OAuth2 Client Registration Params to attributes!", e);
-                throw new IncorrectParameterException("Unable to save OAuth2 Client Registration Params to attributes!");
-            }
+        return getTenantOAuth2ClientsParams(tenantId);
+    }
 
-        } finally {
-            clientRegistrationSaveLock.unlock();
-        }
+    @Transactional
+    private void transactionalSaveTenantOAuth2ClientsParams(TenantId tenantId, OAuth2ClientsParams oAuth2ClientsParams) {
+        long acquireStart = System.currentTimeMillis();
+        lockService.transactionLock(LockKey.OAUTH2_CONFIG);
+        log.trace("[{}] Waited for lock {} ms.", tenantId, System.currentTimeMillis() - acquireStart);
 
-        return getTenantOAuth2ClientsParams(tenantId);
+        validateRegistrationIdUniqueness(oAuth2ClientsParams, tenantId);
+
+        Set<String> domainNames = oAuth2ClientsParams.getClientsDomainsParams().stream()
+                .map(OAuth2ClientsDomainParams::getDomainName)
+                .collect(Collectors.toSet());
+        processTenantAdminSettings(tenantId, domainNames);
+
+        List<AttributeKvEntry> attributes = createOAuth2ClientsParamsAttributes(oAuth2ClientsParams);
+        try {
+            attributesService.save(tenantId, tenantId, DataConstants.SERVER_SCOPE, attributes).get();
+        } catch (Exception e) {
+            log.error("Unable to save OAuth2 Client Registration Params to attributes!", e);
+            throw new IncorrectParameterException("Unable to save OAuth2 Client Registration Params to attributes!");
+        }
     }
 
     private List<AttributeKvEntry> createOAuth2ClientsParamsAttributes(OAuth2ClientsParams oAuth2ClientsParams) {

+/**
+ * Copyright © 2016-2020 The Thingsboard Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.thingsboard.server.dao.sql.lock;
+
+public interface LockRepository {
+    void transactionLock(Integer key);
+}

+/**
+ * Copyright © 2016-2020 The Thingsboard Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.thingsboard.server.dao.sql.lock;
+
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.stereotype.Repository;
+import org.thingsboard.server.dao.util.PsqlDao;
+import org.thingsboard.server.dao.util.SqlDao;
+
+@Slf4j
+@SqlDao
+@PsqlDao
+@Repository
+public class PsqlLockRepository implements LockRepository {
+    private static final String TRANSACTION_LOCK_QUERY = "SELECT pg_advisory_xact_lock(?)";
+
+    @Autowired
+    private JdbcTemplate jdbcTemplate;
+
+    @Override
+    public void transactionLock(Integer key) {
+        jdbcTemplate.query(TRANSACTION_LOCK_QUERY,
+                preparedStatement -> preparedStatement.setInt(1, key),
+                resultSet -> {}
+        );
+    }
+}