[SourceKit] Add function to dispose a request handle

This allows the client to dispose of a request handle manually, cleaning up memory leaks that could previoulsy resulted from cancelling a request that has finished. It also gives us more flexibility to change to a different representation of request handles that require manual disposal in the future.

Author: ahoppen

tools/SourceKit/bindings/python/sourcekitd/capi.py

@@ -315,6 +315,8 @@ def __repr__(self):
 functionList = [
     ("sourcekitd_cancel_request",
      [c_void_p]),
+    ("sourcekitd_request_handle_dispose",
+     [c_void_p]),
 
     ("sourcekitd_initialize",
      None),

tools/SourceKit/tools/sourcekitd-test/sourcekitd-test.cpp

@@ -1228,6 +1228,8 @@ static int handleTestInvocation(TestOptions Opts, TestOptions &InitOpts) {
                             ^(sourcekitd_response_t resp) {
                               auto &info = asyncResponses[respIndex];
                               info.response = resp;
+                              sourcekitd_request_handle_dispose(
+                                  info.requestHandle);
                               info.semaphore.signal(); // Ready to be handled!
                             });
 

tools/SourceKit/tools/sourcekitd/bin/InProc/sourcekitdInProc-darwin.exports

@@ -1,4 +1,5 @@
 sourcekitd_cancel_request
+sourcekitd_request_handle_dispose
 sourcekitd_initialize
 sourcekitd_request_array_create
 sourcekitd_request_array_set_int64

tools/SourceKit/tools/sourcekitd/bin/InProc/sourcekitdInProc.cpp

@@ -162,6 +162,10 @@ void sourcekitd_cancel_request(sourcekitd_request_handle_t handle) {
   sourcekitd::cancelRequest(/*CancellationToken=*/handle);
 }
 
+void sourcekitd_request_handle_dispose(sourcekitd_request_handle_t handle) {
+  sourcekitd::disposeCancellationToken(/*CancellationToken=*/handle);
+}
+
 void
 sourcekitd_set_interrupted_connection_handler(
                           sourcekitd_interrupted_connection_handler_t handler) {

tools/SourceKit/tools/sourcekitd/bin/InProc/sourcekitdInProc.exports

@@ -1,4 +1,5 @@
 sourcekitd_cancel_request
+sourcekitd_request_handle_dispose
 sourcekitd_initialize
 sourcekitd_request_array_create
 sourcekitd_request_array_set_int64

tools/SourceKit/tools/sourcekitd/bin/XPC/Client/sourcekitd.cpp

@@ -227,6 +227,17 @@ void sourcekitd_cancel_request(sourcekitd_request_handle_t handle) {
   xpc_release(msg);
 }
 
+void sourcekitd_request_handle_dispose(sourcekitd_request_handle_t handle) {
+  xpc_connection_t conn = getGlobalConnection();
+  xpc_object_t msg = xpc_dictionary_create(nullptr, nullptr, 0);
+  xpc_dictionary_set_uint64(msg, xpc::KeyDisposeRequestHandle,
+                            reinterpret_cast<uint64_t>(handle));
+
+  xpc_connection_send_message(conn, msg);
+
+  xpc_release(msg);
+}
+
 /// To avoid repeated crashes, used to notify the service to delay typechecking
 /// in the editor for a certain amount of seconds.
 static std::atomic<size_t> SemanticEditorDelaySecondsNum;

tools/SourceKit/tools/sourcekitd/bin/XPC/Client/sourcekitd.exports

@@ -1,4 +1,5 @@
 sourcekitd_cancel_request
+sourcekitd_request_handle_dispose
 sourcekitd_initialize
 sourcekitd_request_array_create
 sourcekitd_request_array_set_int64

tools/SourceKit/tools/sourcekitd/bin/XPC/Service/XPCService.cpp

@@ -275,6 +275,11 @@ static void sourcekitdServer_peer_event_handler(xpc_connection_t peer,
                          xpc_dictionary_get_uint64(event,
                                                    xpc::KeyCancelRequest))) {
         sourcekitd::cancelRequest(/*CancellationToken=*/cancelToken);
+      } else if (SourceKitCancellationToken cancelToken =
+                     reinterpret_cast<SourceKitCancellationToken>(
+                         xpc_dictionary_get_uint64(
+                             event, xpc::KeyDisposeRequestHandle))) {
+        sourcekitd::disposeCancellationToken(/*CancellationToken=*/cancelToken);
       } else {
         assert(false && "unexpected message");
       }

tools/SourceKit/tools/sourcekitd/include/sourcekitd/Internal-XPC.h

@@ -25,6 +25,7 @@ static const char *KeyTracingEnabled = "tracing_enabled";
 static const char *KeyMsgResponse = "response";
 static const char *KeyCancelToken = "cancel_token";
 static const char *KeyCancelRequest = "cancel_request";
+static const char *KeyDisposeRequestHandle = "dispose_request_handle";
 
 enum class Message {
   Initialization,

tools/SourceKit/tools/sourcekitd/include/sourcekitd/sourcekitd.h

@@ -627,6 +627,10 @@ SOURCEKITD_PUBLIC
 void
 sourcekitd_cancel_request(sourcekitd_request_handle_t handle);
 
+/// Dispose a request handle returned by \c sourcekitd_send_request.
+SOURCEKITD_PUBLIC
+void sourcekitd_request_handle_dispose(sourcekitd_request_handle_t handle);
+
 #if SOURCEKITD_HAS_BLOCKS
 
 /// Sets the handler which should be called to receive notifications.