Handle possible nulls from fromJson() in TeragrepDynatraceStep.java (#622)

* checks that JsonObject is not null

* rebased

* changed exception type

* rebased

* limited try catch block to relevant objects only

* removes instance of check

* run spotless

* changes accidentally removed during rebase

* Update src/main/java/com/teragrep/pth_10/steps/teragrep/TeragrepDynatraceStep.java

refactored to remove null checks

Co-authored-by: eemhu <[email protected]>

* run spotless

---------

Co-authored-by: eemhu <[email protected]>

Author: Abigael-JT

src/main/java/com/teragrep/pth_10/steps/teragrep/TeragrepDynatraceStep.java

@@ -45,16 +45,15 @@
  */
 package com.teragrep.pth_10.steps.teragrep;
 
-import com.google.gson.Gson;
-import com.google.gson.JsonElement;
-import com.google.gson.JsonNull;
+import com.google.gson.*;
 import com.google.gson.JsonObject;
 import com.teragrep.functions.dpf_02.AbstractStep;
 import com.teragrep.pth_10.ast.DPLParserCatalystContext;
 import com.teragrep.pth_10.ast.NumericText;
 import com.teragrep.pth_10.ast.TextString;
 import com.teragrep.pth_10.steps.Flushable;
 import com.teragrep.pth_10.steps.teragrep.dynatrace.DynatraceItem;
+import org.apache.http.HttpEntity;
 import org.apache.http.client.methods.CloseableHttpResponse;
 import org.apache.http.client.methods.HttpPost;
 import org.apache.http.entity.StringEntity;
@@ -159,35 +158,54 @@ private void sendPostReq(String urlStr, DynatraceItem dti) throws IOException {
         httpPost.setEntity(new StringEntity(dti.toString(), "utf-8"));
 
         try (
-                CloseableHttpClient client = HttpClients.createDefault();
-                CloseableHttpResponse response = client.execute(httpPost)
+                final CloseableHttpClient client = HttpClients.createDefault();
+                final CloseableHttpResponse response = client.execute(httpPost)
         ) {
             final int statusCode = response.getStatusLine().getStatusCode();
 
-            try (InputStream respStream = response.getEntity().getContent()) {
-                JsonObject jsonResp = new Gson()
-                        .fromJson(new InputStreamReader(respStream, StandardCharsets.UTF_8), JsonObject.class);
-                JsonElement errorElem = jsonResp.get("error");
-                if (!(errorElem instanceof JsonNull)) {
-                    throw new RuntimeException("Error from server response: " + errorElem.toString());
-                }
-                JsonElement validElem = jsonResp.get("linesValid");
-                if (validElem == null) {
-                    throw new RuntimeException("Unexpected JSON: Could not find linesValid element.");
+            final HttpEntity entity = response.getEntity();
+
+            if (entity == null) {
+                throw new IllegalStateException("Response entity was null!");
+            }
+
+            final JsonObject jsonResp;
+            try (final InputStream respStream = entity.getContent()) {
+                final InputStreamReader inputStreamReader = new InputStreamReader(respStream, StandardCharsets.UTF_8);
+                try {
+                    jsonResp = new Gson().fromJson(inputStreamReader, JsonObject.class);
                 }
-                LOGGER.info("Valid lines: <[{}]>", validElem);
-                JsonElement invalidElem = jsonResp.get("linesInvalid");
-                if (invalidElem == null) {
-                    throw new RuntimeException("Unexpected JSON: Could not find linesInvalid element.");
+                catch (final JsonIOException | JsonSyntaxException je) {
+                    throw new IllegalArgumentException("Error parsing JSON response, message: " + je.getMessage());
                 }
-                LOGGER.warn("Invalid lines: <[{}]>", invalidElem);
+            }
+            catch (final IOException | UnsupportedOperationException e) {
+                throw new IllegalStateException("Error getting response stream, message: " + e.getMessage());
+            }
+            if (jsonResp == null || jsonResp.isJsonNull()) {
+                throw new IllegalStateException("Unexpected null JSON response");
             }
 
+            if (jsonResp.has("error") && !jsonResp.get("error").isJsonNull()) {
+                throw new RuntimeException("Error from server response: " + jsonResp.get("error").toString());
+            }
+
+            final boolean hasValidElem = jsonResp.has("linesValid");
+            if (!hasValidElem) {
+                throw new RuntimeException("Unexpected JSON: Could not find linesValid element.");
+            }
+            LOGGER.info("Valid lines: <[{}]>", jsonResp.get("linesValid"));
+
+            final boolean hasInvalidElem = jsonResp.has("linesInvalid");
+            if (!hasInvalidElem) {
+                throw new RuntimeException("Unexpected JSON: Could not find linesInvalid element.");
+            }
+            LOGGER.warn("Invalid lines: <[{}]>", jsonResp.get("linesInvalid"));
+
             if (statusCode != 202 && statusCode != 400) {
                 throw new RuntimeException("Error! Response code: <[" + statusCode + "]>. Expected 202 or 400.");
             }
         }
-
     }
 
     @Override

src/test/java/com/teragrep/pth_10/DynatraceNullAPICallback.java

@@ -0,0 +1,62 @@
+/*
+ * Teragrep Data Processing Language (DPL) translator for Apache Spark (pth_10)
+ * Copyright (C) 2019-2025 Suomen Kanuuna Oy
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *
+ * Additional permission under GNU Affero General Public License version 3
+ * section 7
+ *
+ * If you modify this Program, or any covered work, by linking or combining it
+ * with other code, such other code is not for that reason alone subject to any
+ * of the requirements of the GNU Affero GPL version 3 as long as this Program
+ * is the same Program as licensed from Suomen Kanuuna Oy without any additional
+ * modifications.
+ *
+ * Supplemented terms under GNU Affero General Public License version 3
+ * section 7
+ *
+ * Origin of the software must be attributed to Suomen Kanuuna Oy. Any modified
+ * versions must be marked as "Modified version of" The Program.
+ *
+ * Names of the licensors and authors may not be used for publicity purposes.
+ *
+ * No rights are granted for use of trade names, trademarks, or service marks
+ * which are in The Program if any.
+ *
+ * Licensee must indemnify licensors and authors for any liability that these
+ * contractual assumptions impose on licensors and authors.
+ *
+ * To the extent this program is licensed as part of the Commercial versions of
+ * Teragrep, the applicable Commercial License may apply to this file if you as
+ * a licensee so wish it.
+ */
+package com.teragrep.pth_10;
+
+import org.mockserver.mock.action.ExpectationResponseCallback;
+import org.mockserver.model.HttpRequest;
+import org.mockserver.model.HttpResponse;
+
+public class DynatraceNullAPICallback implements ExpectationResponseCallback {
+
+    public DynatraceNullAPICallback() {
+
+    }
+
+    @Override
+    public HttpResponse handle(HttpRequest httpRequest) {
+        return HttpResponse.response().withStatusCode(202);
+    }
+}

src/test/java/com/teragrep/pth_10/TeragrepDynatraceTest.java

@@ -132,6 +132,10 @@ public void tgDynatraceTest() {
 
         // two lines received
         mockServer.verify(request().withPath("/metrics/ingest"), VerificationTimes.exactly(2));
+
+        mockServer
+                .clear(request().withPath("/metrics/ingest").withMethod("POST").withHeader("Content-Type", "text/plain; charset=utf-8"));
+
     }
 
     @Test
@@ -156,6 +160,10 @@ public void tgDynatraceNoAggregateTest() {
 
         // 0 lines received
         mockServer.verify(request().withPath("/metrics/ingest"), VerificationTimes.never());
+
+        mockServer
+                .clear(request().withPath("/metrics/ingest").withMethod("POST").withHeader("Content-Type", "text/plain; charset=utf-8"));
+
     }
 
     @Test
@@ -182,5 +190,39 @@ public void tgDynatraceNonNumericDataTest() {
 
         // 0 lines received
         mockServer.verify(request().withPath("/metrics/ingest"), VerificationTimes.never());
+
+        mockServer
+                .clear(request().withPath("/metrics/ingest").withMethod("POST").withHeader("Content-Type", "text/plain; charset=utf-8"));
+
+    }
+
+    @Test
+    @DisabledIfSystemProperty(
+            named = "skipSparkTest",
+            matches = "true"
+    )
+    public void tgDynatraceNullResponseTest() {
+        // respond to metrics ingest
+        mockServer
+                .when(request().withPath("/metrics/ingest").withMethod("POST").withHeader("Content-Type", "text/plain; charset=utf-8")).respond(HttpClassCallback.callback(DynatraceNullAPICallback.class));
+
+        // send post
+        Throwable th = this.streamingTestUtil
+                .performThrowingDPLTest(
+                        IllegalStateException.class, "| makeresults count=10 " + "| eval _raw = 1" + "| stats sum(_raw)"
+                                + "| teragrep exec dynatrace metric write",
+                        testFile, ds -> {
+                        }
+                );
+
+        // should not work with null response
+        Assertions.assertEquals("Unexpected null JSON response", th.getMessage());
+
+        // 1 lines received before null response
+        mockServer.verify(request().withPath("/metrics/ingest"), VerificationTimes.once());
+
+        mockServer
+                .clear(request().withPath("/metrics/ingest").withMethod("POST").withHeader("Content-Type", "text/plain; charset=utf-8"));
+
     }
 }