Examples with KeyValue org.hbase.async.KeyValue used on opensource projects

Example 51 with KeyValue

use of org.hbase.async.KeyValue in project opentsdb by OpenTSDB.

the class MetaSync method run.

/**
   * Loops through the entire TSDB data set and exits when complete.
   */
public void run() {
    // list of deferred calls used to act as a buffer
    final ArrayList<Deferred<Boolean>> storage_calls = new ArrayList<Deferred<Boolean>>();
    final Deferred<Object> result = new Deferred<Object>();
    final class ErrBack implements Callback<Object, Exception> {

        @Override
        public Object call(Exception e) throws Exception {
            Throwable ex = e;
            while (ex.getClass().equals(DeferredGroupException.class)) {
                if (ex.getCause() == null) {
                    LOG.warn("Unable to get to the root cause of the DGE");
                    break;
                }
                ex = ex.getCause();
            }
            LOG.error("Sync thread failed with exception", ex);
            result.callback(null);
            return null;
        }
    }
    final ErrBack err_back = new ErrBack();
    /**
     * Called when we have encountered a previously un-processed UIDMeta object.
     * This callback will update the "created" timestamp of the UIDMeta and
     * store the update, replace corrupted metas and update search plugins.
     */
    final class UidCB implements Callback<Deferred<Boolean>, UIDMeta> {

        private final UniqueIdType type;

        private final byte[] uid;

        private final long timestamp;

        /**
       * Constructor that initializes the local callback
       * @param type The type of UIDMeta we're dealing with
       * @param uid The UID of the meta object as a byte array
       * @param timestamp The timestamp of the timeseries when this meta
       * was first detected
       */
        public UidCB(final UniqueIdType type, final byte[] uid, final long timestamp) {
            this.type = type;
            this.uid = uid;
            this.timestamp = timestamp;
        }

        /**
       * A nested class called after fetching a UID name to use when creating a
       * new UIDMeta object if the previous object was corrupted. Also pushes
       * the meta off to the search plugin.
       */
        final class UidNameCB implements Callback<Deferred<Boolean>, String> {

            @Override
            public Deferred<Boolean> call(final String name) throws Exception {
                UIDMeta new_meta = new UIDMeta(type, uid, name);
                new_meta.setCreated(timestamp);
                tsdb.indexUIDMeta(new_meta);
                LOG.info("Replacing corrupt UID [" + UniqueId.uidToString(uid) + "] of type [" + type + "]");
                return new_meta.syncToStorage(tsdb, true);
            }
        }

        @Override
        public Deferred<Boolean> call(final UIDMeta meta) throws Exception {
            // otherwise it's probably an accurate timestamp
            if (meta.getCreated() > (timestamp + 3600) || meta.getCreated() == 0) {
                LOG.info("Updating UID [" + UniqueId.uidToString(uid) + "] of type [" + type + "]");
                meta.setCreated(timestamp);
                // consider it corrupt and replace it with a new object
                if (meta.getUID() == null || meta.getUID().isEmpty() || meta.getType() == null) {
                    return tsdb.getUidName(type, uid).addCallbackDeferring(new UidNameCB());
                } else {
                    // the meta was good, just needed a timestamp update so sync to
                    // search and storage
                    tsdb.indexUIDMeta(meta);
                    LOG.info("Syncing valid UID [" + UniqueId.uidToString(uid) + "] of type [" + type + "]");
                    return meta.syncToStorage(tsdb, false);
                }
            } else {
                LOG.debug("UID [" + UniqueId.uidToString(uid) + "] of type [" + type + "] is up to date in storage");
                return Deferred.fromResult(true);
            }
        }
    }
    /**
     * Called to handle a previously unprocessed TSMeta object. This callback
     * will update the "created" timestamp, create a new TSMeta object if
     * missing, and update search plugins.
     */
    final class TSMetaCB implements Callback<Deferred<Boolean>, TSMeta> {

        private final String tsuid_string;

        private final byte[] tsuid;

        private final long timestamp;

        /**
       * Default constructor
       * @param tsuid ID of the timeseries
       * @param timestamp The timestamp when the first data point was recorded
       */
        public TSMetaCB(final byte[] tsuid, final long timestamp) {
            this.tsuid = tsuid;
            tsuid_string = UniqueId.uidToString(tsuid);
            this.timestamp = timestamp;
        }

        @Override
        public Deferred<Boolean> call(final TSMeta meta) throws Exception {
            /** Called to process the new meta through the search plugin and tree code */
            final class IndexCB implements Callback<Deferred<Boolean>, TSMeta> {

                @Override
                public Deferred<Boolean> call(final TSMeta new_meta) throws Exception {
                    tsdb.indexTSMeta(new_meta);
                    // pass through the trees
                    return tsdb.processTSMetaThroughTrees(new_meta);
                }
            }
            /** Called to load the newly created meta object for passage onto the
         * search plugin and tree builder if configured
         */
            final class GetCB implements Callback<Deferred<Boolean>, Boolean> {

                @Override
                public final Deferred<Boolean> call(final Boolean exists) throws Exception {
                    if (exists) {
                        return TSMeta.getTSMeta(tsdb, tsuid_string).addCallbackDeferring(new IndexCB());
                    } else {
                        return Deferred.fromResult(false);
                    }
                }
            }
            /** Errback on the store new call to catch issues */
            class ErrBack implements Callback<Object, Exception> {

                public Object call(final Exception e) throws Exception {
                    LOG.warn("Failed creating meta for: " + tsuid + " with exception: ", e);
                    return null;
                }
            }
            // new one
            if (meta == null) {
                /**
           * Called after successfully creating a TSMeta counter and object,
           * used to convert the deferred long to a boolean so it can be
           * combined with other calls for waiting.
           */
                final class CreatedCB implements Callback<Deferred<Boolean>, Long> {

                    @Override
                    public Deferred<Boolean> call(Long value) throws Exception {
                        LOG.info("Created counter and meta for timeseries [" + tsuid_string + "]");
                        return Deferred.fromResult(true);
                    }
                }
                /**
           * Called after checking to see if the counter exists and is used
           * to determine if we should create a new counter AND meta or just a
           * new meta
           */
                final class CounterCB implements Callback<Deferred<Boolean>, Boolean> {

                    @Override
                    public Deferred<Boolean> call(final Boolean exists) throws Exception {
                        if (!exists) {
                            // here or in the local callback
                            return TSMeta.incrementAndGetCounter(tsdb, tsuid).addCallbackDeferring(new CreatedCB());
                        } else {
                            TSMeta new_meta = new TSMeta(tsuid, timestamp);
                            tsdb.indexTSMeta(new_meta);
                            LOG.info("Counter exists but meta was null, creating meta data " + "for timeseries [" + tsuid_string + "]");
                            return new_meta.storeNew(tsdb).addCallbackDeferring(new GetCB()).addErrback(new ErrBack());
                        }
                    }
                }
                // improperly before the meta is flushed to storage.
                return TSMeta.counterExistsInStorage(tsdb, tsuid).addCallbackDeferring(new CounterCB());
            }
            // corrupted
            if (meta.getTSUID() == null || meta.getTSUID().isEmpty()) {
                LOG.warn("Replacing corrupt meta data for timeseries [" + tsuid_string + "]");
                TSMeta new_meta = new TSMeta(tsuid, timestamp);
                tsdb.indexTSMeta(new_meta);
                return new_meta.storeNew(tsdb).addCallbackDeferring(new GetCB()).addErrback(new ErrBack());
            } else {
                // hour otherwise it's probably an accurate timestamp
                if (meta.getCreated() > (timestamp + 3600) || meta.getCreated() == 0) {
                    meta.setCreated(timestamp);
                    tsdb.indexTSMeta(meta);
                    LOG.info("Updated created timestamp for timeseries [" + tsuid_string + "]");
                    return meta.syncToStorage(tsdb, false);
                }
                LOG.debug("TSUID [" + tsuid_string + "] is up to date in storage");
                return Deferred.fromResult(false);
            }
        }
    }
    /**
     * Scanner callback that recursively loops through all of the data point
     * rows. Note that we don't process the actual data points, just the row
     * keys.
     */
    final class MetaScanner implements Callback<Object, ArrayList<ArrayList<KeyValue>>> {

        private byte[] last_tsuid = null;

        private String tsuid_string = "";

        /**
       * Fetches the next set of rows from the scanner and adds this class as
       * a callback
       * @return A meaningless deferred to wait on until all data rows have
       * been processed.
       */
        public Object scan() {
            return scanner.nextRows().addCallback(this).addErrback(err_back);
        }

        @Override
        public Object call(ArrayList<ArrayList<KeyValue>> rows) throws Exception {
            if (rows == null) {
                result.callback(null);
                return null;
            }
            for (final ArrayList<KeyValue> row : rows) {
                try {
                    final byte[] tsuid = UniqueId.getTSUIDFromKey(row.get(0).key(), TSDB.metrics_width(), Const.TIMESTAMP_BYTES);
                    // so we save time
                    if (last_tsuid != null && Arrays.equals(last_tsuid, tsuid)) {
                        continue;
                    }
                    last_tsuid = tsuid;
                    // see if we've already processed this tsuid and if so, continue
                    if (processed_tsuids.contains(Arrays.hashCode(tsuid))) {
                        continue;
                    }
                    tsuid_string = UniqueId.uidToString(tsuid);
                    /**
             * An error callback used to catch issues with a particular timeseries
             * or UIDMeta such as a missing UID name. We want to continue
             * processing when this happens so we'll just log the error and
             * the user can issue a command later to clean up orphaned meta
             * entries.
             */
                    final class RowErrBack implements Callback<Object, Exception> {

                        @Override
                        public Object call(Exception e) throws Exception {
                            Throwable ex = e;
                            while (ex.getClass().equals(DeferredGroupException.class)) {
                                if (ex.getCause() == null) {
                                    LOG.warn("Unable to get to the root cause of the DGE");
                                    break;
                                }
                                ex = ex.getCause();
                            }
                            if (ex.getClass().equals(IllegalStateException.class)) {
                                LOG.error("Invalid data when processing TSUID [" + tsuid_string + "]: " + ex.getMessage());
                            } else if (ex.getClass().equals(IllegalArgumentException.class)) {
                                LOG.error("Invalid data when processing TSUID [" + tsuid_string + "]: " + ex.getMessage());
                            } else if (ex.getClass().equals(NoSuchUniqueId.class)) {
                                LOG.warn("Timeseries [" + tsuid_string + "] includes a non-existant UID: " + ex.getMessage());
                            } else {
                                LOG.error("Unknown exception processing row: " + row, ex);
                            }
                            return null;
                        }
                    }
                    // add tsuid to the processed list
                    processed_tsuids.add(Arrays.hashCode(tsuid));
                    // we may have a new TSUID or UIDs, so fetch the timestamp of the 
                    // row for use as the "created" time. Depending on speed we could 
                    // parse datapoints, but for now the hourly row time is enough
                    final long timestamp = Bytes.getUnsignedInt(row.get(0).key(), Const.SALT_WIDTH() + TSDB.metrics_width());
                    LOG.debug("[" + thread_id + "] Processing TSUID: " + tsuid_string + "  row timestamp: " + timestamp);
                    // now process the UID metric meta data
                    final byte[] metric_uid_bytes = Arrays.copyOfRange(tsuid, 0, TSDB.metrics_width());
                    final String metric_uid = UniqueId.uidToString(metric_uid_bytes);
                    Long last_get = metric_uids.get(metric_uid);
                    if (last_get == null || last_get == 0 || timestamp < last_get) {
                        // fetch and update. Returns default object if the meta doesn't
                        // exist, so we can just call sync on this to create a missing
                        // entry
                        final UidCB cb = new UidCB(UniqueIdType.METRIC, metric_uid_bytes, timestamp);
                        final Deferred<Boolean> process_uid = UIDMeta.getUIDMeta(tsdb, UniqueIdType.METRIC, metric_uid_bytes).addCallbackDeferring(cb).addErrback(new RowErrBack());
                        storage_calls.add(process_uid);
                        metric_uids.put(metric_uid, timestamp);
                    }
                    // loop through the tags and process their meta
                    final List<byte[]> tags = UniqueId.getTagsFromTSUID(tsuid_string);
                    int idx = 0;
                    for (byte[] tag : tags) {
                        final UniqueIdType type = (idx % 2 == 0) ? UniqueIdType.TAGK : UniqueIdType.TAGV;
                        idx++;
                        final String uid = UniqueId.uidToString(tag);
                        // check the maps to see if we need to bother updating
                        if (type == UniqueIdType.TAGK) {
                            last_get = tagk_uids.get(uid);
                        } else {
                            last_get = tagv_uids.get(uid);
                        }
                        if (last_get != null && last_get != 0 && last_get <= timestamp) {
                            continue;
                        }
                        // fetch and update. Returns default object if the meta doesn't
                        // exist, so we can just call sync on this to create a missing
                        // entry
                        final UidCB cb = new UidCB(type, tag, timestamp);
                        final Deferred<Boolean> process_uid = UIDMeta.getUIDMeta(tsdb, type, tag).addCallbackDeferring(cb).addErrback(new RowErrBack());
                        storage_calls.add(process_uid);
                        if (type == UniqueIdType.TAGK) {
                            tagk_uids.put(uid, timestamp);
                        } else {
                            tagv_uids.put(uid, timestamp);
                        }
                    }
                    // handle the timeseries meta last so we don't record it if one
                    // or more of the UIDs had an issue
                    final Deferred<Boolean> process_tsmeta = TSMeta.getTSMeta(tsdb, tsuid_string).addCallbackDeferring(new TSMetaCB(tsuid, timestamp)).addErrback(new RowErrBack());
                    storage_calls.add(process_tsmeta);
                } catch (RuntimeException e) {
                    LOG.error("Processing row " + row + " failed with exception: " + e.getMessage());
                    LOG.debug("Row: " + row + " stack trace: ", e);
                }
            }
            /**
         * A buffering callback used to avoid StackOverflowError exceptions
         * where the list of deferred calls can exceed the limit. Instead we'll
         * process the Scanner's limit in rows, wait for all of the storage
         * calls to complete, then continue on to the next set.
         */
            final class ContinueCB implements Callback<Object, ArrayList<Boolean>> {

                @Override
                public Object call(ArrayList<Boolean> puts) throws Exception {
                    storage_calls.clear();
                    return scan();
                }
            }
            /**
         * Catch exceptions in one of the grouped calls and continue scanning.
         * Without this the user may not see the exception and the thread will
         * just die silently.
         */
            final class ContinueEB implements Callback<Object, Exception> {

                @Override
                public Object call(Exception e) throws Exception {
                    Throwable ex = e;
                    while (ex.getClass().equals(DeferredGroupException.class)) {
                        if (ex.getCause() == null) {
                            LOG.warn("Unable to get to the root cause of the DGE");
                            break;
                        }
                        ex = ex.getCause();
                    }
                    LOG.error("[" + thread_id + "] Upstream Exception: ", ex);
                    return scan();
                }
            }
            // call ourself again but wait for the current set of storage calls to
            // complete so we don't OOM
            Deferred.group(storage_calls).addCallback(new ContinueCB()).addErrback(new ContinueEB());
            return null;
        }
    }
    final MetaScanner scanner = new MetaScanner();
    try {
        scanner.scan();
        result.joinUninterruptibly();
        LOG.info("[" + thread_id + "] Complete");
    } catch (Exception e) {
        LOG.error("[" + thread_id + "] Scanner Exception", e);
        throw new RuntimeException("[" + thread_id + "] Scanner exception", e);
    }
}

Example 52 with KeyValue

use of org.hbase.async.KeyValue in project opentsdb by OpenTSDB.

the class TreeRule method fetchRule.

/**
   * Attempts to retrieve the specified tree rule from storage.
   * @param tsdb The TSDB to use for storage access
   * @param tree_id ID of the tree the rule belongs to
   * @param level Level where the rule resides
   * @param order Order where the rule resides
   * @return A TreeRule object if found, null if it does not exist
   * @throws HBaseException if there was an issue
   * @throws IllegalArgumentException if the one of the required parameters was
   * missing
   * @throws JSONException if the object could not be serialized
   */
public static Deferred<TreeRule> fetchRule(final TSDB tsdb, final int tree_id, final int level, final int order) {
    if (tree_id < 1 || tree_id > 65535) {
        throw new IllegalArgumentException("Invalid Tree ID");
    }
    if (level < 0) {
        throw new IllegalArgumentException("Invalid rule level");
    }
    if (order < 0) {
        throw new IllegalArgumentException("Invalid rule order");
    }
    // fetch the whole row
    final GetRequest get = new GetRequest(tsdb.treeTable(), Tree.idToBytes(tree_id));
    get.family(Tree.TREE_FAMILY());
    get.qualifier(getQualifier(level, order));
    /**
     * Called after fetching to parse the results
     */
    final class FetchCB implements Callback<Deferred<TreeRule>, ArrayList<KeyValue>> {

        @Override
        public Deferred<TreeRule> call(final ArrayList<KeyValue> row) {
            if (row == null || row.isEmpty()) {
                return Deferred.fromResult(null);
            }
            return Deferred.fromResult(parseFromStorage(row.get(0)));
        }
    }
    return tsdb.getClient().get(get).addCallbackDeferring(new FetchCB());
}

Example 53 with KeyValue

use of org.hbase.async.KeyValue in project opentsdb by OpenTSDB.

the class TreeRule method deleteAllRules.

/**
   * Attempts to delete all rules belonging to the given tree.
   * @param tsdb The TSDB to use for storage access
   * @param tree_id ID of the tree the rules belongs to
   * @return A deferred to wait on for completion. The value has no meaning and
   * may be null.
   * @throws HBaseException if there was an issue
   * @throws IllegalArgumentException if the one of the required parameters was
   * missing
   */
public static Deferred<Object> deleteAllRules(final TSDB tsdb, final int tree_id) {
    if (tree_id < 1 || tree_id > 65535) {
        throw new IllegalArgumentException("Invalid Tree ID");
    }
    // fetch the whole row
    final GetRequest get = new GetRequest(tsdb.treeTable(), Tree.idToBytes(tree_id));
    get.family(Tree.TREE_FAMILY());
    /**
     * Called after fetching the requested row. If the row is empty, we just
     * return, otherwise we compile a list of qualifiers to delete and submit
     * a single delete request to storage.
     */
    final class GetCB implements Callback<Deferred<Object>, ArrayList<KeyValue>> {

        @Override
        public Deferred<Object> call(final ArrayList<KeyValue> row) throws Exception {
            if (row == null || row.isEmpty()) {
                return Deferred.fromResult(null);
            }
            final ArrayList<byte[]> qualifiers = new ArrayList<byte[]>(row.size());
            for (KeyValue column : row) {
                if (column.qualifier().length > RULE_PREFIX.length && Bytes.memcmp(RULE_PREFIX, column.qualifier(), 0, RULE_PREFIX.length) == 0) {
                    qualifiers.add(column.qualifier());
                }
            }
            final DeleteRequest delete = new DeleteRequest(tsdb.treeTable(), Tree.idToBytes(tree_id), Tree.TREE_FAMILY(), qualifiers.toArray(new byte[qualifiers.size()][]));
            return tsdb.getClient().delete(delete);
        }
    }
    return tsdb.getClient().get(get).addCallbackDeferring(new GetCB());
}

Example 54 with KeyValue

use of org.hbase.async.KeyValue in project opentsdb by OpenTSDB.

the class TimeSeriesLookup method lookupAsync.

/**
   * Lookup time series associated with the given metric, tagk, tagv or tag 
   * pairs. Either the meta table or the data table will be scanned. If no
   * metric is given, a full table scan must be performed and this call may take
   * a long time to complete. 
   * When dumping to stdout, if an ID can't be looked up, it will be logged and
   * skipped.
   * @return A list of TSUIDs matching the given lookup query.
   * @throws NoSuchUniqueName if any of the given names fail to resolve to a 
   * UID.
   * @since 2.2
   */
public Deferred<List<byte[]>> lookupAsync() {
    final Pattern tagv_regex = tagv_filter != null ? Pattern.compile(tagv_filter) : null;
    // we don't really know what size the UIDs will resolve to so just grab
    // a decent amount.
    final StringBuffer buf = to_stdout ? new StringBuffer(2048) : null;
    final long start = System.currentTimeMillis();
    final int limit;
    if (query.getLimit() > 0) {
        if (query.useMeta() || Const.SALT_WIDTH() < 1) {
            limit = query.getLimit();
        } else if (query.getLimit() < Const.SALT_BUCKETS()) {
            limit = 1;
        } else {
            limit = query.getLimit() / Const.SALT_BUCKETS();
        }
    } else {
        limit = 0;
    }
    class ScannerCB implements Callback<Deferred<List<byte[]>>, ArrayList<ArrayList<KeyValue>>> {

        private final Scanner scanner;

        // used to avoid dupes when scanning the data table
        private byte[] last_tsuid = null;

        private int rows_read;

        ScannerCB(final Scanner scanner) {
            this.scanner = scanner;
        }

        Deferred<List<byte[]>> scan() {
            return scanner.nextRows().addCallbackDeferring(this);
        }

        @Override
        public Deferred<List<byte[]>> call(final ArrayList<ArrayList<KeyValue>> rows) throws Exception {
            if (rows == null) {
                scanner.close();
                if (query.useMeta() || Const.SALT_WIDTH() < 1) {
                    LOG.debug("Lookup query matched " + tsuids.size() + " time series in " + (System.currentTimeMillis() - start) + " ms");
                }
                return Deferred.fromResult(tsuids);
            }
            for (final ArrayList<KeyValue> row : rows) {
                if (limit > 0 && rows_read >= limit) {
                    // little recursion to close the scanner and log above.
                    return call(null);
                }
                final byte[] tsuid = query.useMeta() ? row.get(0).key() : UniqueId.getTSUIDFromKey(row.get(0).key(), TSDB.metrics_width(), Const.TIMESTAMP_BYTES);
                // string objects.
                if (tagv_regex != null && !tagv_regex.matcher(new String(tsuid, CHARSET)).find()) {
                    continue;
                }
                if (to_stdout) {
                    if (last_tsuid != null && Bytes.memcmp(last_tsuid, tsuid) == 0) {
                        continue;
                    }
                    last_tsuid = tsuid;
                    try {
                        buf.append(UniqueId.uidToString(tsuid)).append(" ");
                        buf.append(RowKey.metricNameAsync(tsdb, tsuid).joinUninterruptibly());
                        buf.append(" ");
                        final List<byte[]> tag_ids = UniqueId.getTagPairsFromTSUID(tsuid);
                        final Map<String, String> resolved_tags = Tags.resolveIdsAsync(tsdb, tag_ids).joinUninterruptibly();
                        for (final Map.Entry<String, String> tag_pair : resolved_tags.entrySet()) {
                            buf.append(tag_pair.getKey()).append("=").append(tag_pair.getValue()).append(" ");
                        }
                    } catch (NoSuchUniqueId nsui) {
                        LOG.error("Unable to resolve UID in TSUID (" + UniqueId.uidToString(tsuid) + ") " + nsui.getMessage());
                    }
                    // reset the buffer so we can re-use it
                    buf.setLength(0);
                } else {
                    tsuids.add(tsuid);
                }
                ++rows_read;
            }
            return scan();
        }

        @Override
        public String toString() {
            return "Scanner callback";
        }
    }
    class CompleteCB implements Callback<List<byte[]>, ArrayList<List<byte[]>>> {

        @Override
        public List<byte[]> call(final ArrayList<List<byte[]>> unused) throws Exception {
            LOG.debug("Lookup query matched " + tsuids.size() + " time series in " + (System.currentTimeMillis() - start) + " ms");
            return tsuids;
        }

        @Override
        public String toString() {
            return "Final async lookup callback";
        }
    }
    class UIDCB implements Callback<Deferred<List<byte[]>>, Object> {

        @Override
        public Deferred<List<byte[]>> call(Object arg0) throws Exception {
            if (!query.useMeta() && Const.SALT_WIDTH() > 0 && metric_uid != null) {
                final ArrayList<Deferred<List<byte[]>>> deferreds = new ArrayList<Deferred<List<byte[]>>>(Const.SALT_BUCKETS());
                for (int i = 0; i < Const.SALT_BUCKETS(); i++) {
                    deferreds.add(new ScannerCB(getScanner(i)).scan());
                }
                return Deferred.group(deferreds).addCallback(new CompleteCB());
            } else {
                return new ScannerCB(getScanner(0)).scan();
            }
        }

        @Override
        public String toString() {
            return "UID resolution callback";
        }
    }
    return resolveUIDs().addCallbackDeferring(new UIDCB());
}

Example 55 with KeyValue

use of org.hbase.async.KeyValue in project opentsdb by OpenTSDB.

the class Tree method fetchAllTrees.

/**
   * Attempts to retrieve all trees from the UID table, including their rules.
   * If no trees were found, the result will be an empty list
   * @param tsdb The TSDB to use for storage
   * @return A list of tree objects. May be empty if none were found
   */
public static Deferred<List<Tree>> fetchAllTrees(final TSDB tsdb) {
    final Deferred<List<Tree>> result = new Deferred<List<Tree>>();
    /**
     * Scanner callback that recursively calls itself to load the next set of
     * rows from storage. When the scanner returns a null, the callback will
     * return with the list of trees discovered.
     */
    final class AllTreeScanner implements Callback<Object, ArrayList<ArrayList<KeyValue>>> {

        private final List<Tree> trees = new ArrayList<Tree>();

        private final Scanner scanner;

        public AllTreeScanner() {
            scanner = setupAllTreeScanner(tsdb);
        }

        /**
       * Fetches the next set of results from the scanner and adds this class
       * as a callback.
       * @return A list of trees if the scanner has reached the end
       */
        public Object fetchTrees() {
            return scanner.nextRows().addCallback(this);
        }

        @Override
        public Object call(ArrayList<ArrayList<KeyValue>> rows) throws Exception {
            if (rows == null) {
                result.callback(trees);
                return null;
            }
            for (ArrayList<KeyValue> row : rows) {
                final Tree tree = new Tree();
                for (KeyValue column : row) {
                    if (column.qualifier().length >= TREE_QUALIFIER.length && Bytes.memcmp(TREE_QUALIFIER, column.qualifier()) == 0) {
                        // it's *this* tree. We deserialize to a new object and copy
                        // since the columns could be in any order and we may get a rule 
                        // before the tree object
                        final Tree local_tree = JSON.parseToObject(column.value(), Tree.class);
                        tree.created = local_tree.created;
                        tree.description = local_tree.description;
                        tree.name = local_tree.name;
                        tree.notes = local_tree.notes;
                        tree.strict_match = local_tree.strict_match;
                        tree.enabled = local_tree.enabled;
                        tree.store_failures = local_tree.store_failures;
                        // WARNING: Since the JSON data in storage doesn't contain the tree
                        // ID, we need to parse it from the row key
                        tree.setTreeId(bytesToId(row.get(0).key()));
                    // tree rule
                    } else if (column.qualifier().length > TreeRule.RULE_PREFIX().length && Bytes.memcmp(TreeRule.RULE_PREFIX(), column.qualifier(), 0, TreeRule.RULE_PREFIX().length) == 0) {
                        final TreeRule rule = TreeRule.parseFromStorage(column);
                        tree.addRule(rule);
                    }
                }
                // only add the tree if we parsed a valid ID
                if (tree.tree_id > 0) {
                    trees.add(tree);
                }
            }
            // recurse to get the next set of rows from the scanner
            return fetchTrees();
        }
    }
    // start the scanning process
    new AllTreeScanner().fetchTrees();
    return result;
}