ResourceScope Class — netty Architecture

Source Code

common/src/main/java/io/netty/util/LeakPresenceDetector.java lines 260–329

    public static final class ResourceScope implements Closeable {
        final String name;
        final LongAdder openResourceCounter = new LongAdder();
        final Map<PresenceTracker<?>, Throwable> creationStacks =
                TRACK_CREATION_STACK ? new ConcurrentHashMap<>() : null;
        boolean closed;

        /**
         * Create a new scope.
         *
         * @param name The scope name, used for error reporting
         */
        public ResourceScope(String name) {
            this.name = name;
        }

        void checkOpen() {
            if (closed) {
                throw new AllocationProhibitedException("Resource scope '" + name + "' already closed");
            }
        }

        void check() {
            long n = openResourceCounter.sumThenReset();
            if (n != 0) {
                StringBuilder msg = new StringBuilder("Possible memory leak detected for resource scope '")
                        .append(name).append("'. ");
                if (n < 0) {
                    msg.append("Resource count was negative: A resource previously reported as a leak was released " +
                            "after all. Please ensure that that resource is released before its test finishes.");
                    throw new IllegalStateException(msg.toString());
                }
                if (TRACK_CREATION_STACK) {
                    msg.append("Creation stack traces:");
                    IllegalStateException ise = new IllegalStateException(msg.toString());
                    int i = 0;
                    for (Throwable t : creationStacks.values()) {
                        ise.addSuppressed(t);
                        if (i++ > 5) {
                            break;
                        }
                    }
                    creationStacks.clear();
                    throw ise;
                }
                msg.append("Please use paranoid leak detection to get more information, or set " +
                        "-D" + TRACK_CREATION_STACK_PROPERTY + "=true");
                throw new IllegalStateException(msg.toString());
            }
        }

        /**
         * Check whether there are any open resources left, and {@link #close()} would throw.
         *
         * @return {@code true} if there are open resources
         */
        public boolean hasOpenResources() {
            return openResourceCounter.sum() > 0;
        }

        /**
         * Close this scope. Closing a scope will prevent new resources from being allocated (or released) in this
         * scope. The call also throws an exception if there are any resources left open.
         */
        @Override
        public void close() {
            closed = true;
            check();
        }
    }