Clojure / RocksDB Java interop examples

example.clj

(ns com.biffweb.impl.index
  (:require [taoensso.nippy :as nippy])
  (:import java.util.Map
           java.util.HashMap
           java.util.function.Function
           (java.io Closeable File)
           (java.nio.file Files Path)
           java.nio.file.attribute.FileAttribute
           (org.rocksdb BlockBasedTableConfig Checkpoint CompressionType FlushOptions LRUCache
                        DBOptions Options ReadOptions RocksDB RocksIterator
                        WriteBatchWithIndex WriteBatch WriteOptions Statistics StatsLevel
                        ColumnFamilyOptions ColumnFamilyDescriptor ColumnFamilyHandle BloomFilter))
  )


(comment

  (RocksDB/loadLibrary)

  ;; need to close
  (def cf-opts (.optimizeUniversalStyleCompaction (ColumnFamilyOptions.)))

  (def cf-descriptors (java.util.ArrayList. [(ColumnFamilyDescriptor. RocksDB/DEFAULT_COLUMN_FAMILY cf-opts)
                                             (ColumnFamilyDescriptor. (.getBytes "cf-1") cf-opts)
                                             (ColumnFamilyDescriptor. (.getBytes "cf-2") cf-opts)]))

  ;; need to close (before the db)
  (def cf-handles (java.util.ArrayList.))

  ;; need to close
  (def db-options (.. (DBOptions.)
                      (setCreateIfMissing true)
                      (setCreateMissingColumnFamilies true)))


  ;; need to close
  (def db (RocksDB/open db-options "rocksdb-index-test" cf-descriptors cf-handles))

  (def id->handle (into {}
                        (map (fn [cf-handle]
                               [(String. (.getName cf-handle)) cf-handle]))
                        cf-handles))


  (.put db (id->handle "cf-1") (.getBytes "foo") (.getBytes "bar"))
  (String. (.get db (id->handle "cf-1") (.getBytes "foo")))
  (.put db (id->handle "cf-2") (.getBytes "foo") (.getBytes "quux"))
  (String. (.get db (id->handle "cf-2") (.getBytes "foo")))

  (.dropColumnFamily db (id->handle "cf-1"))
  (.close (id->handle "cf-1"))
  (def new-handle (.createColumnFamily db (ColumnFamilyDescriptor. (.getBytes "cf-1") cf-opts)))
  (def id->handle (assoc id->handle "cf-1" new-handle))


  (with-open [batch (WriteBatch.)
              write-options (WriteOptions.)]
    (.put batch (id->handle "cf-1") (.getBytes "a") (.getBytes "b"))
    (.put batch (id->handle "cf-1") (.getBytes "c") (.getBytes "d"))
    (.write db write-options batch)
    )
  (String. (.get db (id->handle "cf-1") (.getBytes "a")))
  (String. (.get db (id->handle "cf-1") (.getBytes "c")))

  (mapv #(String. %) (.multiGetAsList db
                                      (java.util.ArrayList. [(id->handle "cf-1") (id->handle "cf-1")])
                                      (java.util.ArrayList. [(.getBytes "a") (.getBytes "c")])))

  ;; need to close
  (def snapshot (.getSnapshot db))
  ;; need to close
  (def read-options (doto (ReadOptions.) (.setSnapshot snapshot)))

  (String. (.get db (id->handle "cf-1") (.getBytes "foo")))
  (String. (.get db (id->handle "cf-1") read-options (.getBytes "foo")))
  (.put db (id->handle "cf-1") (.getBytes "foo") (.getBytes "abc"))

  (.close read-options)

  (.releaseSnapshot db snapshot)

  (.close snapshot)

  )