Give ResponseStore for code actions a minimum history size of 8.

Author: ethan-vanderheijden

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/handlers/CodeActionHandler.java

@@ -25,6 +25,8 @@
 import java.util.concurrent.ForkJoinPool;
 import java.util.stream.Collectors;
 
+import javax.tools.Diagnostic;
+
 import org.apache.commons.lang3.StringUtils;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IProgressMonitor;
@@ -50,6 +52,7 @@
 import org.eclipse.jdt.ls.core.internal.corrections.QuickFixProcessor;
 import org.eclipse.jdt.ls.core.internal.corrections.RefactorProcessor;
 import org.eclipse.jdt.ls.core.internal.corrections.proposals.NewCUProposal;
+import org.eclipse.jdt.ls.core.internal.handlers.CodeActionHandler.CodeActionData;
 import org.eclipse.jdt.ls.core.internal.preferences.PreferenceManager;
 import org.eclipse.jdt.ls.core.internal.preferences.Preferences;
 import org.eclipse.jdt.ls.core.internal.text.correction.AssignToVariableAssistCommandProposal;
@@ -67,18 +70,19 @@
 import org.eclipse.lsp4j.CodeActionOptions;
 import org.eclipse.lsp4j.CodeActionParams;
 import org.eclipse.lsp4j.Command;
-import org.eclipse.lsp4j.Diagnostic;
 import org.eclipse.lsp4j.DiagnosticSeverity;
-import org.eclipse.lsp4j.Range;
 import org.eclipse.lsp4j.WorkspaceEdit;
 import org.eclipse.lsp4j.jsonrpc.messages.Either;
 
 import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
 
 public class CodeActionHandler {
+	// Store a few of the latest Code Action results because any one of them might be resolved further.
+	// Multiple Code Actions are computed in parallel through ForkJoinPool's common pool leading to a race condition where
+	// the last Code Action request to finish processing is not the client's latest request. History size must scale with pool size.
 	public static final ResponseStore<Either<ChangeCorrectionProposalCore, CodeActionProposal>> codeActionStore
-		= new ResponseStore<>(ForkJoinPool.commonPool().getParallelism());
+			= new ResponseStore<>(Math.max(ForkJoinPool.getCommonPoolParallelism(), 8));
 	public static final String COMMAND_ID_APPLY_EDIT = "java.apply.workspaceEdit";
 
 	public static CodeActionOptions createOptions(PreferenceManager preferenceManager) {