boolean updateCurrentFile()

in src/com/amazon/kinesis/streaming/agent/tailing/SourceFileTracker.java [316:367]
41 lines of code
10 McCabe index (conditional complexity)

    boolean updateCurrentFile(TrackedFileList newSnapshot) throws IOException {
        Preconditions.checkNotNull(currentSnapshot);
        Preconditions.checkNotNull(currentOpenFile);
        TrackedFileList oldSnapshot = currentSnapshot;
        TrackedFile oldCurrentOpenFile = currentOpenFile;

        // Initialize the analysis and log any anomalies
        TrackedFileRotationAnalyzer analyzer = new TrackedFileRotationAnalyzer(currentSnapshot, newSnapshot, currentOpenFile);
        if(!analyzer.getIncomingAnomalies().isEmpty()) {
            for(Map.Entry<TrackedFile, String> anomaly : analyzer.getIncomingAnomalies().entrySet()) {
                onUnexpectedChangeDetected(newSnapshot, anomaly.getKey(), anomaly.getValue());
            }
        }

        // Flag to tell if we managed to track the current open file
        boolean currentFileTracked = false;
        if(!analyzer.checkNoRotation()) {
            onPossibleRotationDetected(newSnapshot);
            if (!analyzer.allFilesHaveDisappeared()) {
                if(analyzer.hasCounterpart(currentOpenFile)) {
                    if(analyzer.currentOpenFileWasTruncated()) {
                        // If current file was truncated, we need to do something.
                        int newIndex = analyzer.findCurrentOpenFileAfterTruncate();
                        if(newIndex >= 0) {
                            currentFileTracked = onRotationByTruncate(newSnapshot, newIndex);
                        } else {
                            currentFileTracked = onTruncationWithoutRotation(newSnapshot);
                        }
                    } else {
                        // Otherwise, all is well. We resume tailing same file.
                        currentFileTracked = continueTailingCurrentFile(newSnapshot, analyzer.getCounterpartIndex(currentOpenFile));
                    }
                } else {
                    // Current open file disappeared somehow.
                    // None of our supported rotations methods could explain this.
                    currentFileTracked = onCurrentFileNotFound(newSnapshot);
                }
            } else {
                currentFileTracked = onAllFilesDisappeared(newSnapshot);
            }
        } else {
            currentFileTracked = onNoRotationDetected(newSnapshot, analyzer.getCounterpartIndex(currentOpenFile));
        }

        // SANITYCHECK: After we run, the current snapshot and current file must have changed.
        if(currentSnapshot == oldSnapshot) // identity intended
            throw new IllegalStateException("The current tracked file snapshot was not updated as expected.");
        if(currentOpenFile == oldCurrentOpenFile)  // identity intended
            throw new IllegalStateException("The current open file was not updated as expected.");

        return currentFileTracked;
    }