QpackEncoderDynamicTable Class — netty Architecture

Source Code

codec-http3/src/main/java/io/netty/handler/codec/http3/QpackEncoderDynamicTable.java lines 31–490

final class QpackEncoderDynamicTable {
    private static final QpackException INVALID_KNOW_RECEIVED_COUNT_INCREMENT =
            QpackException.newStatic(QpackDecoder.class, "incrementKnownReceivedCount(...)",
                    "QPACK - invalid known received count increment.");
    private static final QpackException INVALID_REQUIRED_INSERT_COUNT_INCREMENT =
            QpackException.newStatic(QpackDecoder.class, "acknowledgeInsertCount(...)",
                    "QPACK - invalid required insert count acknowledgment.");
    private static final QpackException INVALID_TABLE_CAPACITY =
            QpackException.newStatic(QpackDecoder.class, "validateCapacity(...)",
                    "QPACK - dynamic table capacity is invalid.");
    private static final QpackException CAPACITY_ALREADY_SET =
            QpackException.newStatic(QpackDecoder.class, "maxTableCapacity(...)",
                    "QPACK - dynamic table capacity is already set.");
    /**
     * Special return value of {@link #getEntryIndex(CharSequence, CharSequence)} when the entry is not found.
     */
    public static final int NOT_FOUND = Integer.MIN_VALUE;

    /**
     * A hashmap of header entries.
     */
    private final HeaderEntry[] fields;

    /**
     * Percentage of capacity that we expect to be free after eviction of old entries.
     */
    private final int expectedFreeCapacityPercentage;

    /**
     * Hash mask for all entries in the hashmap.
     */
    private final byte hashMask;

    /**
     * <a href="https://www.rfc-editor.org/rfc/rfc9204.html#name-dynamic-table-size">Current size of the table</a>.
     */
    private long size;

    /**
     * <a href="https://www.rfc-editor.org/rfc/rfc9204.html#name-maximum-dynamic-table-capac">
     *     Maximum capacity of the table</a>. This is set once based on the
     *     {@link Http3SettingsFrame#HTTP3_SETTINGS_QPACK_MAX_TABLE_CAPACITY} received by the remote peer.
     */
    private long maxTableCapacity = -1;

    /*
     * The below indexes follow the suggested heuristics in Section 2.1.1.1 Avoiding Prohibited insertions
     * https://www.rfc-editor.org/rfc/rfc9204.html#name-avoiding-prohibited-inserti
     *
     *                Tail                             Drain       Head
     *                 |                                |           |
     *                 v                                v           v
     *       +--------+---------------------------------+----------+
     *       | Unused |          Referenceable          | Draining |
     *       | Space  |             Entries             | Entries  |
     *       +--------+---------------------------------+----------+
     *                ^                                 ^          ^
     *                |                                 |          |
     *          Insertion Index                 Draining Index  Dropping Index
     */

    /**
     * Head of the entries, such that {@link HeaderEntry#index} is the {@code droppingIndex}.
     */
    private final HeaderEntry head;

    /**
     * Pointer before which entries are marked for eviction post {@link #incrementKnownReceivedCount(int)}.
     * {@link HeaderEntry#index} is the {@code drainingIndex}.
     */
    private HeaderEntry drain;

     /**
     * Pointer to the entry representing the <a
     * href="https://quicwg.org/base-drafts/draft-ietf-quic-qpack.html#name-known-received-count">
     * known received count</a>.
     */
    private HeaderEntry knownReceived;

    /**
     * Tail of the entries, such that {@link HeaderEntry#index} is the {@code insertionIndex}.