TraceRecord Class — netty Architecture

Source Code

common/src/main/java/io/netty/util/ResourceLeakDetector.java lines 668–738

    private static class TraceRecord extends Throwable {
        private static final long serialVersionUID = 6065153674892850720L;
        public static final int BOTTOM_POS = -1;
        public static final int CLOSE_MARK_POS = -2;

        private static final TraceRecord BOTTOM = new TraceRecord(false) {
            private static final long serialVersionUID = 7396077602074694571L;

            // Override fillInStackTrace() so we not populate the backtrace via a native call and so leak the
            // Classloader.
            // See https://github.com/netty/netty/pull/10691
            @Override
            public Throwable fillInStackTrace() {
                return this;
            }
        };

        private final String hintString;
        private final TraceRecord next;
        private final int pos;

        TraceRecord(TraceRecord next, Object hint) {
            // This needs to be generated even if toString() is never called as it may change later on.
            hintString = hint instanceof ResourceLeakHint ? ((ResourceLeakHint) hint).toHintString() : hint.toString();
            this.next = next;
            this.pos = next.pos + 1;
        }

        TraceRecord(TraceRecord next) {
           hintString = null;
           this.next = next;
           this.pos = next.pos + 1;
        }

        // Used to terminate the stack
        private TraceRecord(boolean closeMarker) {
            hintString = null;
            next = null;
            pos = closeMarker ? CLOSE_MARK_POS : BOTTOM_POS;
        }

        @Override
        public String toString() {
            StringBuilder buf = new StringBuilder(2048);
            if (hintString != null) {
                buf.append("\tHint: ").append(hintString).append(NEWLINE);
            }

            // Append the stack trace.
            StackTraceElement[] array = getStackTrace();
            // Skip the first three elements.
            out: for (int i = 3; i < array.length; i++) {
                StackTraceElement element = array[i];
                // Strip the noisy stack trace elements.
                String[] exclusions = excludedMethods.get();
                for (int k = 0; k < exclusions.length; k += 2) {
                    // Suppress a warning about out of bounds access
                    // since the length of excludedMethods is always even, see addExclusions()
                    if (exclusions[k].equals(element.getClassName())
                            && exclusions[k + 1].equals(element.getMethodName())) {
                        continue out;
                    }
                }

                buf.append('\t');
                buf.append(element.toString());
                buf.append(NEWLINE);
            }
            return buf.toString();
        }
    }