refactor: minor cleanups (#1082)

Remove synchronized methods in favor of volatile variables, since
mergeTriggers is an static method, a volatile variable is enough.

Remove catch of a CancellationException which is not thrown by
CompletableFuture#cancel and use CancellationSupport.

Use Either#map instead of ternary expression.

org.eclipse.lsp4e/src/org/eclipse/lsp4e/internal/CancellationSupport.java

@@ -20,7 +20,7 @@
 
 /**
  * LSP cancellation support hosts the list of LSP requests to cancel when a
- * process is canceled (ex: when completion is re-triggered, when hover is give
+ * process is cancelled (ex: when completion is re-triggered, when hover is give
  * up, etc)
  *
  * @see <a href=

org.eclipse.lsp4e/src/org/eclipse/lsp4e/operations/completion/LSContentAssistProcessor.java

@@ -54,16 +54,15 @@
 import org.eclipse.lsp4j.CompletionItem;
 import org.eclipse.lsp4j.CompletionItemDefaults;
 import org.eclipse.lsp4j.CompletionList;
-import org.eclipse.lsp4j.CompletionOptions;
 import org.eclipse.lsp4j.CompletionParams;
-import org.eclipse.lsp4j.SignatureHelpOptions;
 import org.eclipse.lsp4j.SignatureHelpParams;
 import org.eclipse.lsp4j.SignatureInformation;
 import org.eclipse.lsp4j.jsonrpc.CancelChecker;
 import org.eclipse.lsp4j.jsonrpc.ResponseErrorException;
 import org.eclipse.lsp4j.jsonrpc.messages.Either;
 import org.eclipse.ui.texteditor.ITextEditor;
 
+import com.google.common.base.Functions;
 import com.google.common.base.Strings;
 
 public class LSContentAssistProcessor implements IContentAssistProcessor {
@@ -76,18 +75,21 @@ public class LSContentAssistProcessor implements IContentAssistProcessor {
  private @Nullable String errorMessage;
  private final boolean errorAsCompletionItem;
  private @Nullable CompletableFuture<List<Void>> completionLanguageServersFuture;
- private final Object completionTriggerCharsSemaphore = new Object();
- private char[] completionTriggerChars = NO_CHARS;
+ private volatile char[] completionTriggerChars = NO_CHARS;
  private @Nullable CompletableFuture<List<Void>> contextInformationLanguageServersFuture;
- private final Object contextTriggerCharsSemaphore = new Object();
- private char[] contextTriggerChars = NO_CHARS;
+ private volatile char[] contextTriggerChars = NO_CHARS;
  private final boolean incompleteAsCompletionItem;
 
  /**
  * The cancellation support used to cancel previous LSP requests
  * 'textDocument/completion' when completion is retriggered
  */
- private CancellationSupport cancellationSupport;
+ private CancellationSupport completionCancellationSupport;
+ /**
+ * The cancellation support used to cancel previous LSP requests
+ * for fetching the trigger characters
+ */
+ private CancellationSupport triggerCharsCancellationSupport;
 
  public LSContentAssistProcessor() {
  this(true);
@@ -99,7 +101,8 @@ public LSContentAssistProcessor(boolean errorAsCompletionItem) {
 
  public LSContentAssistProcessor(boolean errorAsCompletionItem, boolean incompleteAsCompletionItem) {
  this.errorAsCompletionItem = errorAsCompletionItem;
- this.cancellationSupport = new CancellationSupport();
+ this.completionCancellationSupport = new CancellationSupport();
+ this.triggerCharsCancellationSupport = new CancellationSupport();
  this.incompleteAsCompletionItem = incompleteAsCompletionItem;
  }
 
@@ -133,14 +136,14 @@ public LSContentAssistProcessor(boolean errorAsCompletionItem, boolean incomplet
  try {
  // Cancel the previous LSP requests 'textDocument/completions' and
  // completionLanguageServersFuture
- this.cancellationSupport.cancel();
+ this.completionCancellationSupport.cancel();
 
  // Initialize a new cancel support to register:
  // - LSP requests 'textDocument/completions'
  // - completionLanguageServersFuture
  final var cancellationSupport = new CancellationSupport();
- final var completionLanguageServersFuture = this.completionLanguageServersFuture = LanguageServers
- .forDocument(document).withFilter(capabilities -> capabilities.getCompletionProvider() != null) //
+ final var completionLanguageServersFuture = this.completionLanguageServersFuture = cancellationSupport.execute(
+ LanguageServers.forDocument(document).withFilter(capabilities -> capabilities.getCompletionProvider() != null) //
  .collectAll((w, ls) -> cancellationSupport.execute(ls.getTextDocumentService().completion(param)) //
  .thenAccept(completion -> {
  boolean isIncomplete = completion != null && completion.isRight()
@@ -156,9 +159,8 @@ public LSContentAssistProcessor(boolean errorAsCompletionItem, boolean incomplet
  .formatted(w.serverDefinition.label), t);
  }
  return null;
- }));
- cancellationSupport.execute(completionLanguageServersFuture);
- this.cancellationSupport = cancellationSupport;
+ })));
+ this.completionCancellationSupport = cancellationSupport;
 
  // Wait for the result of all LSP requests 'textDocument/completions', this
  // future will be canceled with the next completion
@@ -216,43 +218,28 @@ private String createErrorMessage(int offset, Exception ex) {
 
  private void initiateLanguageServers(IDocument document) {
  if (currentDocument != document) {
- this.currentDocument = document;
- if (this.completionLanguageServersFuture != null) {
- try {
- this.completionLanguageServersFuture.cancel(true);
- } catch (CancellationException ex) {
- // nothing
- }
- }
- if (this.contextInformationLanguageServersFuture != null) {
- try {
- this.contextInformationLanguageServersFuture.cancel(true);
- } catch (CancellationException ex) {
- // nothing
- }
- }
- this.completionTriggerChars = NO_CHARS;
- this.contextTriggerChars = NO_CHARS;
+ currentDocument = document;
+ triggerCharsCancellationSupport.cancel();
+
+ completionTriggerChars = NO_CHARS;
+ contextTriggerChars = NO_CHARS;
 
- this.completionLanguageServersFuture = LanguageServers.forDocument(document)
+ completionLanguageServersFuture = triggerCharsCancellationSupport.execute(//
+ LanguageServers.forDocument(document)
  .withFilter(capabilities -> capabilities.getCompletionProvider() != null) //
  .collectAll((w, ls) -> {
- CompletionOptions provider = castNonNull(w.getServerCapabilities()).getCompletionProvider();
- synchronized (completionTriggerCharsSemaphore) {
- completionTriggerChars = mergeTriggers(completionTriggerChars,
- provider.getTriggerCharacters());
- }
+ List<String> triggerChars = castNonNull(w.getServerCapabilities()).getCompletionProvider().getTriggerCharacters();
+ completionTriggerChars = mergeTriggers(completionTriggerChars,triggerChars);
  return CompletableFuture.completedFuture(null);
- });
- this.contextInformationLanguageServersFuture = LanguageServers.forDocument(document)
+ }));
+ contextInformationLanguageServersFuture = triggerCharsCancellationSupport.execute(//
+ LanguageServers.forDocument(document)
  .withFilter(capabilities -> capabilities.getSignatureHelpProvider() != null) //
  .collectAll((w, ls) -> {
- SignatureHelpOptions provider = castNonNull(w.getServerCapabilities()).getSignatureHelpProvider();
- synchronized (contextTriggerCharsSemaphore) {
- contextTriggerChars = mergeTriggers(contextTriggerChars, provider.getTriggerCharacters());
- }
+ List<String> triggerChars = castNonNull(w.getServerCapabilities()).getSignatureHelpProvider().getTriggerCharacters();
+ contextTriggerChars = mergeTriggers(contextTriggerChars, triggerChars);
  return CompletableFuture.completedFuture(null);
- });
+ }));
  }
 
  }
@@ -276,16 +263,15 @@ private static List<ICompletionProposal> toProposals(IDocument document, int off
  // Stop the compute of ICompletionProposal if the completion has been cancelled
  cancelChecker.checkCanceled();
  CompletionItemDefaults defaults = completionList.map(o -> null, CompletionList::getItemDefaults);
- List<CompletionItem> items = completionList.isLeft() ? completionList.getLeft()
- : completionList.getRight().getItems();
- return items.stream() //
- .filter(Objects::nonNull).map(item -> new LSCompletionProposal(document, offset, item, defaults,
- languageServerWrapper, isIncomplete))
+ return completionList.map( Functions.identity(), CompletionList::getItems).stream() //
+ .filter(Objects::nonNull) //
+ .map(item -> new LSCompletionProposal(document, offset, item, defaults, languageServerWrapper, isIncomplete))
  .filter(proposal -> {
  // Stop the compute of ICompletionProposal if the completion has been cancelled
  cancelChecker.checkCanceled();
  return true;
- }).filter(proposal -> proposal.validate(document, offset, null)).map(ICompletionProposal.class::cast)
+ }).filter(proposal -> proposal.validate(document, offset, null)) //
+ .map(ICompletionProposal.class::cast)
  .toList();
  }