android - 如何等待 ObservableEmitter 返回 onComplete()

Question

我在TrackerConnectionManager课堂上有以下方法

    @Override
    public Observable<TrackerFile> deleteFiles(final List<TrackerFile> trackerFiles) {
        Observable<TrackerFile> deleteFilesObservable = Observable.create(new ObservableOnSubscribe<TrackerFile>() {
            @Override
            public void subscribe(@NonNull ObservableEmitter<TrackerFile> emitter) throws Exception {
                Log.i(TAG, "deleteFiles() --> subscribe() --> trackerFiles.size(): " + trackerFiles.size());

                for (TrackerFile file : trackerFiles) {
                    Log.i(TAG, "deleteFiles() --> subscribe() --> emitter.onNext(trackerConnectionAPI.deleteFile()): " + file.getFileName());
                    final boolean success = trackerConnectionAPI.deleteFile((char) file.getFileId());

                    // Error mitigation in case that TrackerConnectionAPI returns false
                    if (success) {
                        emitter.onNext(file);
                    } else {
                        Log.w(TAG, "trackerConnectionAPI.deleteFile() return false for file: " + file);
                    }
                }
                Log.i(TAG, "deleteFiles() --> subscribe() --> emitter.onComplete()");
                emitter.onComplete();
            }
        });

这应该调用cleanTracker方法：

    private void startTrackerRoutine() {
        Disposable disposable = trackerConnectionManager.iterateFiles()
                .subscribe(trackerFiles -> {
                    if (trackerFiles.isEmpty()) {
                        Log.d(TAG, "startTrackerRoutine() --> no files on Tracker --> disconnect & startNoSessionFoundFragment");
                        disconnectFromTracker();
                        activity.startNoSessionFoundFragment();
                        return;
                    }
                    Log.i(TAG, "startTrackerRoutine() --> Tracker has " + trackerFiles.size() + " files to process.");

                    // TODO: THIS CALL NEEDS TO BE BLOCKING; else we have a RACE CONDITION with the actual transfer of files
                    cleanTracker(trackerFiles);


                    ArrayList<TrackerFile> newSessions = SessionFileHelper.findNewSessions(trackerFiles, tracker.getId(), realm);
                    Log.i(TAG, "startTrackerRoutine() --> found newSessions: " + newSessions);

                    if (newSessions.isEmpty()) {
                        Log.d(TAG, "startTrackerRoutine() --> NO NEW Sessions --> disconnect & startNoSessionFoundFragment");
                        disconnectFromTracker();
                        activity.startNoSessionFoundFragment();
                    } else {
                        activity.startTransferSessionFragment(newSessions);
                    }
                }, throwable -> {
                    Log.e(TAG, "startTrackerRoutine() --> ERROR in trackerConnectionManager.iterateFiles() --> disconnectFromTracker()", throwable);
                    disconnectFromTracker();
                    if (throwable instanceof ForeignSessionException) {
                        fragment.showForeignTrackerDialog();
                    } else {
                        fragment.showConnectionFailedDialog();
                    }
                });
        activeRequests.add(disposable);
    }

现在我想知道，如何调用此deleteFiles()方法并等待它完成 -->emitter.onComplete()被调用。

---

我试过这个：

    private void cleanTracker(final List<TrackerFile> trackerFiles) {
        final List<TrackerFile> filesToDelete = SessionFileHelper.findNonSessionFiles(trackerFiles);
        Log.i(TAG, "cleanTracker() --> found " + filesToDelete.size() + " files to be deleted");

        Disposable disposable = trackerConnectionManager.deleteFiles(filesToDelete)
                .subscribe(trackerFile -> {
                    if (trackerFile != null) {
                        Log.d(TAG, "cleanTracker() --> successfully deleted: " + trackerFile);
                    } else {
                        Log.w(TAG, "cleanTracker() --> FAILED to delete a file");
                    }

                }, throwable -> {
                    Log.e(TAG, "cleanTracker() --> ERROR while deleting files: " + filesToDelete);
                });

        Log.d(TAG, "cleanTracker() --> activeRequests.add(disposable)");
        activeRequests.add(disposable);
    }

但这对我没有帮助，因为它并没有真正等待/阻塞，直到所有文件都被删除并且其他命令弄乱了我的套接字连接。

标签： androidrx-java2

Answer 1

等待子流程完成是concat*操作员的工作。您的情况可以通过以下方式解决concatMap：

private void startTrackerRoutine() {
    Disposable disposable = trackerConnectionManager.iterateFiles()
            .observeOn(Schedulers.io())
            .concatMap(trackerFiles -> {
                 if (trackerFiles.isEmpty()) {
                    Log.d(TAG, "startTrackerRoutine() --> no files on Tracker --> disconnect & startNoSessionFoundFragment");
                    disconnectFromTracker();
                    activity.startNoSessionFoundFragment();
                    return Observable.empty();
                }
                Log.i(TAG, "startTrackerRoutine() --> Tracker has " + trackerFiles.size() + " files to process.");
                return cleanTrackerFlow(trackerFiles);
            })
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(trackerFiles -> {
                ArrayList<TrackerFile> newSessions = SessionFileHelper.findNewSessions(trackerFiles, tracker.getId(), realm);
                Log.i(TAG, "startTrackerRoutine() --> found newSessions: " + newSessions);

                if (newSessions.isEmpty()) {
                    Log.d(TAG, "startTrackerRoutine() --> NO NEW Sessions --> disconnect & startNoSessionFoundFragment");
                    disconnectFromTracker();
                    activity.startNoSessionFoundFragment();
                } else {
                    activity.startTransferSessionFragment(newSessions);
                }
            }, throwable -> {
                Log.e(TAG, "startTrackerRoutine() --> ERROR in trackerConnectionManager.iterateFiles() --> disconnectFromTracker()", throwable);
                disconnectFromTracker();
                if (throwable instanceof ForeignSessionException) {
                    fragment.showForeignTrackerDialog();
                } else {
                    fragment.showConnectionFailedDialog();
                }
            });
    activeRequests.add(disposable);
}

private Observable<List<TrackerFile>> cleanTracker(final List<TrackerFile> trackerFiles) {
    final List<TrackerFile> filesToDelete = SessionFileHelper.findNonSessionFiles(trackerFiles);
    Log.i(TAG, "cleanTracker() --> found " + filesToDelete.size() + " files to be deleted");

    return trackerConnectionManager.deleteFiles(filesToDelete)
            .doOnNext(trackerFile -> {
                Log.d(TAG, "cleanTracker() --> successfully deleted: " + trackerFile);
            })
            .doOnError(throwable -> {
                Log.e(TAG, "cleanTracker() --> ERROR while deleting files: " + filesToDelete);
            })
            .ignoreElements()
            .andThen(Observable.just(trackerFiles));
}