Fix renderer memory issues by writing to OutputStream

cli/src/main/java/org/openapitools/openapidiff/cli/Main.java

@@ -2,9 +2,9 @@
 
 import ch.qos.logback.classic.Level;
 import io.swagger.v3.parser.core.models.AuthorizationValue;
-import java.io.File;
-import java.io.IOException;
-import java.nio.charset.StandardCharsets;
+import java.io.ByteArrayOutputStream;
+import java.io.FileOutputStream;
+import java.io.OutputStreamWriter;
 import java.util.Collections;
 import java.util.List;
 import org.apache.commons.cli.CommandLine;
@@ -14,7 +14,6 @@
 import org.apache.commons.cli.Option;
 import org.apache.commons.cli.Options;
 import org.apache.commons.cli.ParseException;
-import org.apache.commons.io.FileUtils;
 import org.apache.commons.lang3.exception.ExceptionUtils;
 import org.openapitools.openapidiff.core.OpenApiCompare;
 import org.openapitools.openapidiff.core.model.ChangedOpenApi;
@@ -175,29 +174,33 @@ public static void main(String... args) {
       ChangedOpenApi result = OpenApiCompare.fromLocations(oldPath, newPath, auths);
       ConsoleRender consoleRender = new ConsoleRender();
       if (!logLevel.equals("OFF")) {
-        System.out.println(consoleRender.render(result));
+        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+        OutputStreamWriter outputStreamWriter = new OutputStreamWriter(outputStream);
+        consoleRender.render(result, outputStreamWriter);
+        System.out.println(outputStream);
       }
       if (line.hasOption("html")) {
         HtmlRender htmlRender = new HtmlRender();
-        String output = htmlRender.render(result);
-        String outputFile = line.getOptionValue("html");
-        writeOutput(output, outputFile);
+        FileOutputStream outputStream = new FileOutputStream(line.getOptionValue("html"));
+        OutputStreamWriter outputStreamWriter = new OutputStreamWriter(outputStream);
+        htmlRender.render(result, outputStreamWriter);
       }
       if (line.hasOption("markdown")) {
         MarkdownRender mdRender = new MarkdownRender();
-        String output = mdRender.render(result);
-        String outputFile = line.getOptionValue("markdown");
-        writeOutput(output, outputFile);
+        FileOutputStream outputStream = new FileOutputStream(line.getOptionValue("markdown"));
+        OutputStreamWriter outputStreamWriter = new OutputStreamWriter(outputStream);
+        mdRender.render(result, outputStreamWriter);
       }
       if (line.hasOption("text")) {
-        String output = consoleRender.render(result);
-        String outputFile = line.getOptionValue("text");
-        writeOutput(output, outputFile);
+        FileOutputStream outputStream = new FileOutputStream(line.getOptionValue("text"));
+        OutputStreamWriter outputStreamWriter = new OutputStreamWriter(outputStream);
+        consoleRender.render(result, outputStreamWriter);
       }
       if (line.hasOption("json")) {
         JsonRender jsonRender = new JsonRender();
-        String outputFile = line.getOptionValue("json");
-        jsonRender.renderToFile(result, outputFile);
+        FileOutputStream outputStream = new FileOutputStream(line.getOptionValue("json"));
+        OutputStreamWriter outputStreamWriter = new OutputStreamWriter(outputStream);
+        jsonRender.render(result, outputStreamWriter);
       }
       if (line.hasOption("state")) {
         System.out.println(result.isChanged().getValue());
@@ -222,17 +225,6 @@ public static void main(String... args) {
     }
   }
 
-  private static void writeOutput(String output, String outputFile) {
-    File file = new File(outputFile);
-    logger.debug("Output file: {}", file.getAbsolutePath());
-    try {
-      FileUtils.writeStringToFile(file, output, StandardCharsets.UTF_8);
-    } catch (IOException e) {
-      logger.error("Impossible to write output to file {}", outputFile, e);
-      System.exit(2);
-    }
-  }
-
   public static void printHelp(Options options) {
     HelpFormatter formatter = new HelpFormatter();
     formatter.printHelp("openapi-diff <old> <new>", options);

core/src/main/java/org/openapitools/openapidiff/core/exception/RendererException.java

@@ -0,0 +1,12 @@
+package org.openapitools.openapidiff.core.exception;
+
+public class RendererException extends RuntimeException {
+
+  public RendererException(Throwable cause) {
+    super(cause);
+  }
+
+  public RendererException(String message, Throwable cause) {
+    super(message, cause);
+  }
+}

core/src/main/java/org/openapitools/openapidiff/core/output/ConsoleRender.java

@@ -6,11 +6,14 @@
 import io.swagger.v3.oas.models.media.Schema;
 import io.swagger.v3.oas.models.parameters.Parameter;
 import io.swagger.v3.oas.models.responses.ApiResponse;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Optional;
 import org.apache.commons.lang3.StringUtils;
+import org.openapitools.openapidiff.core.exception.RendererException;
 import org.openapitools.openapidiff.core.model.*;
 import org.openapitools.openapidiff.core.utils.RefPointer;
 import org.openapitools.openapidiff.core.utils.RefType;
@@ -21,81 +24,78 @@ public class ConsoleRender implements Render {
   protected ChangedOpenApi diff;
 
   @Override
-  public String render(ChangedOpenApi diff) {
+  public void render(ChangedOpenApi diff, OutputStreamWriter outputStreamWriter) {
     this.diff = diff;
-    StringBuilder output = new StringBuilder();
     if (diff.isUnchanged()) {
-      output.append("No differences. Specifications are equivalents");
+      safelyAppend(outputStreamWriter, "No differences. Specifications are equivalents");
     } else {
-      output
-          .append(bigTitle("Api Change Log"))
-          .append(StringUtils.center(diff.getNewSpecOpenApi().getInfo().getTitle(), LINE_LENGTH))
-          .append(System.lineSeparator());
+      safelyAppend(outputStreamWriter, bigTitle("Api Change Log"));
+      safelyAppend(
+          outputStreamWriter,
+          StringUtils.center(diff.getNewSpecOpenApi().getInfo().getTitle(), LINE_LENGTH));
+      safelyAppend(outputStreamWriter, System.lineSeparator());
 
       List<Endpoint> newEndpoints = diff.getNewEndpoints();
-      String ol_newEndpoint = listEndpoints(newEndpoints, "What's New");
+      listEndpoints(newEndpoints, "What's New", outputStreamWriter);
 
       List<Endpoint> missingEndpoints = diff.getMissingEndpoints();
-      String ol_missingEndpoint = listEndpoints(missingEndpoints, "What's Deleted");
+      listEndpoints(missingEndpoints, "What's Deleted", outputStreamWriter);
 
       List<Endpoint> deprecatedEndpoints = diff.getDeprecatedEndpoints();
-      String ol_deprecatedEndpoint = listEndpoints(deprecatedEndpoints, "What's Deprecated");
+      listEndpoints(deprecatedEndpoints, "What's Deprecated", outputStreamWriter);
 
       List<ChangedOperation> changedOperations = diff.getChangedOperations();
-      String ol_changed = ol_changed(changedOperations);
-
-      output
-          .append(renderBody(ol_newEndpoint, ol_missingEndpoint, ol_deprecatedEndpoint, ol_changed))
-          .append(title("Result"))
-          .append(
-              StringUtils.center(
-                  diff.isCompatible()
-                      ? "API changes are backward compatible"
-                      : "API changes broke backward compatibility",
-                  LINE_LENGTH))
-          .append(System.lineSeparator())
-          .append(separator('-'));
+      ol_changed(changedOperations, outputStreamWriter);
+
+      safelyAppend(
+          outputStreamWriter,
+          StringUtils.center(
+              diff.isCompatible()
+                  ? "API changes are backward compatible"
+                  : "API changes broke backward compatibility",
+              LINE_LENGTH));
+      safelyAppend(outputStreamWriter, System.lineSeparator());
+      safelyAppend(outputStreamWriter, separator('-'));
+    }
+    try {
+      outputStreamWriter.close();
+    } catch (IOException e) {
+      throw new RendererException(e);
     }
-    return output.toString();
   }
 
-  private String ol_changed(List<ChangedOperation> operations) {
+  private void ol_changed(
+      List<ChangedOperation> operations, OutputStreamWriter outputStreamWriter) {
     if (null == operations || operations.isEmpty()) {
-      return "";
+      return;
     }
-    StringBuilder sb = new StringBuilder();
-    sb.append(title("What's Changed"));
+    safelyAppend(outputStreamWriter, title("What's Changed"));
     for (ChangedOperation operation : operations) {
       String pathUrl = operation.getPathUrl();
       String method = operation.getHttpMethod().toString();
       String desc =
           Optional.ofNullable(operation.getSummary()).map(ChangedMetadata::getRight).orElse("");
 
-      StringBuilder ul_detail = new StringBuilder();
       if (result(operation.getParameters()).isDifferent()) {
-        ul_detail
-            .append(StringUtils.repeat(' ', 2))
-            .append("Parameter:")
-            .append(System.lineSeparator())
-            .append(ul_param(operation.getParameters()));
+        safelyAppend(outputStreamWriter, StringUtils.repeat(' ', 2));
+        safelyAppend(outputStreamWriter, "Parameter:");
+        safelyAppend(outputStreamWriter, System.lineSeparator());
+        safelyAppend(outputStreamWriter, ul_param(operation.getParameters()));
       }
       if (operation.resultRequestBody().isDifferent()) {
-        ul_detail
-            .append(StringUtils.repeat(' ', 2))
-            .append("Request:")
-            .append(System.lineSeparator())
-            .append(ul_content(operation.getRequestBody().getContent(), true));
+        safelyAppend(outputStreamWriter, StringUtils.repeat(' ', 2));
+        safelyAppend(outputStreamWriter, "Request:");
+        safelyAppend(outputStreamWriter, System.lineSeparator());
+        safelyAppend(outputStreamWriter, ul_content(operation.getRequestBody().getContent(), true));
       }
       if (operation.resultApiResponses().isDifferent()) {
-        ul_detail
-            .append(StringUtils.repeat(' ', 2))
-            .append("Return Type:")
-            .append(System.lineSeparator())
-            .append(ul_response(operation.getApiResponses()));
+        safelyAppend(outputStreamWriter, StringUtils.repeat(' ', 2));
+        safelyAppend(outputStreamWriter, "Return Type:");
+        safelyAppend(outputStreamWriter, System.lineSeparator());
+        safelyAppend(outputStreamWriter, ul_response(operation.getApiResponses()));
       }
-      sb.append(itemEndpoint(method, pathUrl, desc)).append(ul_detail);
+      safelyAppend(outputStreamWriter, itemEndpoint(method, pathUrl, desc));
     }
-    return sb.toString();
   }
 
   private String ul_response(ChangedApiResponse changedApiResponse) {
@@ -279,7 +279,8 @@ private String li_changedParam(ChangedParameter changeParam) {
     }
   }
 
-  private String listEndpoints(List<Endpoint> endpoints, String title) {
+  private String listEndpoints(
+      List<Endpoint> endpoints, String title, OutputStreamWriter outputStreamWriter) {
     if (null == endpoints || endpoints.isEmpty()) {
       return "";
     }
@@ -317,8 +318,7 @@ public String title(String title, char ch) {
         separator(ch), little, StringUtils.center(title, LINE_LENGTH - 4), little, separator(ch));
   }
 
-  public StringBuilder separator(char ch) {
-    StringBuilder sb = new StringBuilder();
-    return sb.append(StringUtils.repeat(ch, LINE_LENGTH)).append(System.lineSeparator());
+  public String separator(char ch) {
+    return StringUtils.repeat(ch, LINE_LENGTH) + System.lineSeparator();
   }
 }

core/src/main/java/org/openapitools/openapidiff/core/output/HtmlRender.java

@@ -26,16 +26,20 @@
 import io.swagger.v3.oas.models.media.Schema;
 import io.swagger.v3.oas.models.parameters.Parameter;
 import io.swagger.v3.oas.models.responses.ApiResponse;
+import j2html.rendering.FlatHtml;
 import j2html.tags.ContainerTag;
 import j2html.tags.specialized.DivTag;
 import j2html.tags.specialized.HtmlTag;
 import j2html.tags.specialized.LiTag;
 import j2html.tags.specialized.OlTag;
 import j2html.tags.specialized.UlTag;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Optional;
+import org.openapitools.openapidiff.core.exception.RendererException;
 import org.openapitools.openapidiff.core.model.ChangedApiResponse;
 import org.openapitools.openapidiff.core.model.ChangedContent;
 import org.openapitools.openapidiff.core.model.ChangedMediaType;
@@ -71,7 +75,7 @@ public HtmlRender(String title, String linkCss) {
     this.linkCss = linkCss;
   }
 
-  public String render(ChangedOpenApi diff) {
+  public void render(ChangedOpenApi diff, OutputStreamWriter outputStreamWriter) {
     this.diff = diff;
 
     List<Endpoint> newEndpoints = diff.getNewEndpoints();
@@ -86,10 +90,16 @@ public String render(ChangedOpenApi diff) {
     List<ChangedOperation> changedOperations = diff.getChangedOperations();
     OlTag ol_changed = ol_changed(changedOperations);
 
-    return renderHtml(ol_newEndpoint, ol_missingEndpoint, ol_deprecatedEndpoint, ol_changed);
+    renderHtml(
+        ol_newEndpoint, ol_missingEndpoint, ol_deprecatedEndpoint, ol_changed, outputStreamWriter);
   }
 
-  public String renderHtml(OlTag ol_new, OlTag ol_miss, OlTag ol_deprec, OlTag ol_changed) {
+  public void renderHtml(
+      OlTag ol_new,
+      OlTag ol_miss,
+      OlTag ol_deprec,
+      OlTag ol_changed,
+      OutputStreamWriter outputStreamWriter) {
     HtmlTag html =
         html()
             .attr("lang", "en")
@@ -110,7 +120,14 @@ public String renderHtml(OlTag ol_new, OlTag ol_miss, OlTag ol_deprec, OlTag ol_
                                 div().with(h2("What's Deprecated"), hr(), ol_deprec),
                                 div().with(h2("What's Changed"), hr(), ol_changed))));
 
-    return document().render() + html.render();
+    try {
+      FlatHtml<OutputStreamWriter> flatHtml = FlatHtml.into(outputStreamWriter);
+      document().render(flatHtml);
+      html.render(flatHtml);
+      outputStreamWriter.close();
+    } catch (IOException e) {
+      throw new RendererException("Problem rendering html document.", e);
+    }
   }
 
   private OlTag ol_newEndpoint(List<Endpoint> endpoints) {

core/src/main/java/org/openapitools/openapidiff/core/output/JsonRender.java

@@ -4,7 +4,8 @@
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import java.io.IOException;
-import java.nio.file.Paths;
+import java.io.OutputStreamWriter;
+import org.openapitools.openapidiff.core.exception.RendererException;
 import org.openapitools.openapidiff.core.model.ChangedOpenApi;
 
 public class JsonRender implements Render {
@@ -17,21 +18,14 @@ public JsonRender() {
   }
 
   @Override
-  public String render(ChangedOpenApi diff) {
+  public void render(ChangedOpenApi diff, OutputStreamWriter outputStreamWriter) {
     try {
-      return objectMapper.writeValueAsString(diff);
+      objectMapper.writeValue(outputStreamWriter, diff);
+      outputStreamWriter.close();
     } catch (JsonProcessingException e) {
-      throw new RuntimeException("Could not serialize diff as JSON", e);
-    }
-  }
-
-  public void renderToFile(ChangedOpenApi diff, String file) {
-    try {
-      objectMapper.writeValue(Paths.get(file).toFile(), diff);
-    } catch (JsonProcessingException e) {
-      throw new RuntimeException("Could not serialize diff as JSON", e);
+      throw new RendererException("Could not serialize diff as JSON", e);
     } catch (IOException e) {
-      throw new RuntimeException("Could not write to JSON file", e);
+      throw new RendererException(e);
     }
   }
 }