chore(implementation)!: use Jetty-12 core without servlets

Port the invoker to upgrade to Eclipse Jetty-12 version 12.  Specifically using the new core APIs of Eclipse Jetty-12 that allow the overhead of a Servlet container to be avoided.   Several other minor optimizations are included.

BREAKING CHANGE: use Java 17 or above, as required by Eclipse Jetty-12.

Author: gregw

invoker/core/src/main/java/com/google/cloud/functions/invoker/http/HttpRequestImpl.java

@@ -22,19 +22,18 @@
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
-import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Optional;
 import java.util.TreeMap;
 import java.util.concurrent.ExecutionException;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 import org.eclipse.jetty.http.HttpField;
 import org.eclipse.jetty.http.HttpFields;
 import org.eclipse.jetty.http.HttpHeader;
+import org.eclipse.jetty.http.MimeTypes;
 import org.eclipse.jetty.http.MultiPart;
 import org.eclipse.jetty.http.MultiPart.Part;
 import org.eclipse.jetty.http.MultiPartFormData;
@@ -149,7 +148,7 @@ public BufferedReader getReader() throws IOException {
       }
       inputStream = Content.Source.asInputStream(request);
       reader = new BufferedReader(new InputStreamReader(getInputStream(),
-          getCharacterEncoding().orElse(StandardCharsets.UTF_8.name())));
+          Objects.requireNonNullElse(Request.getCharset(request), StandardCharsets.UTF_8)));
     }
     return reader;
   }
@@ -169,9 +168,11 @@ static Map<String, List<String>> toStringListMap(HttpFields headers) {
 
   private static class HttpPartImpl implements HttpPart {
     private final Part part;
+    private final String contentType;
 
     private HttpPartImpl(Part part) {
       this.part = part;
+      contentType = part.getHeaders().get(HttpHeader.CONTENT_TYPE);
     }
 
     public String getName() {
@@ -185,7 +186,7 @@ public Optional<String> getFileName() {
 
     @Override
     public Optional<String> getContentType() {
-      return Optional.ofNullable(part.getHeaders().get(HttpHeader.CONTENT_TYPE));
+      return Optional.ofNullable(contentType);
     }
 
     @Override
@@ -195,13 +196,7 @@ public long getContentLength() {
 
     @Override
     public Optional<String> getCharacterEncoding() {
-      String contentType = getContentType().orElse(null);
-      if (contentType == null) {
-        return Optional.empty();
-      }
-      Pattern charsetPattern = Pattern.compile("(?i).*;\\s*charset\\s*=([^;\\s]*)\\s*(;|$)");
-      Matcher matcher = charsetPattern.matcher(contentType);
-      return matcher.matches() ? Optional.of(matcher.group(1)) : Optional.empty();
+      return Optional.ofNullable(MimeTypes.getCharsetFromContentType(contentType));
     }
 
     @Override
@@ -211,19 +206,17 @@ public InputStream getInputStream() throws IOException {
 
     @Override
     public BufferedReader getReader() throws IOException {
-      String encoding = getCharacterEncoding().orElse("utf-8");
-      return new BufferedReader(new InputStreamReader(getInputStream(), encoding));
+      return new BufferedReader(
+          new InputStreamReader(getInputStream(),
+              Objects.requireNonNullElse(MimeTypes.DEFAULTS.getCharset(contentType),
+                  StandardCharsets.UTF_8)));
     }
 
     @Override
     public Map<String, List<String>> getHeaders() {
       return HttpRequestImpl.toStringListMap(part.getHeaders());
     }
 
-    private static <T> List<T> list(Collection<T> collection) {
-      return (collection instanceof List<?>) ? (List<T>) collection : new ArrayList<>(collection);
-    }
-
     @Override
     public String toString() {
       return "%s{%s}".formatted(super.toString(), part);

invoker/core/src/main/java/com/google/cloud/functions/invoker/http/HttpResponseImpl.java

@@ -34,6 +34,7 @@ public class HttpResponseImpl implements HttpResponse {
   private final Response response;
   private OutputStream outputStream;
   private BufferedWriter writer;
+  private Charset charset;
 
   public HttpResponseImpl(Response response) {
     this.response = response;
@@ -53,6 +54,7 @@ public void setStatusCode(int code, String message) {
   @Override
   public void setContentType(String contentType) {
     response.getHeaders().put(HttpHeader.CONTENT_TYPE, contentType);
+    charset = response.getRequest().getContext().getMimeTypes().getCharset(contentType);
   }
 
   @Override
@@ -62,7 +64,11 @@ public Optional<String> getContentType() {
 
   @Override
   public void appendHeader(String key, String value) {
-    response.getHeaders().add(key, value);
+    if (HttpHeader.CONTENT_TYPE.is(key)) {
+      setContentType(value);
+    } else {
+      response.getHeaders().add(key, value);
+    }
   }
 
   @Override
@@ -87,13 +93,10 @@ public synchronized BufferedWriter getWriter() throws IOException {
       if (outputStream != null) {
         throw new IllegalStateException("getOutputStream called");
       }
-      String contentType = getContentType().orElse(null);
-      Charset charset = Objects.requireNonNullElse(
-          response.getRequest().getContext().getMimeTypes().getCharset(contentType),
-          StandardCharsets.UTF_8);
-      // TODO should we buffer in the input stream rather than as characters
       outputStream = Content.Sink.asOutputStream(response);
-      writer = new BufferedWriter(WriteThroughWriter.newWriter(getOutputStream(), charset));
+      // TODO extend close in such a way as to make the buffer flush the last write.
+      writer = new BufferedWriter(WriteThroughWriter.newWriter(getOutputStream(),
+          Objects.requireNonNullElse(charset, StandardCharsets.UTF_8)));
     }
     return writer;
   }