Updating README, config option naming, and removing dead code.

Author: twilmes

README.md

@@ -9,8 +9,6 @@ JanusGraph, coupled with the FoundationDB storage adapter provides the following
 * High availability
 * ACID transactions
 
-# Limitations
-
 # Compatibility Matrix
 
 |FDB Storage Adapter|JanusGraph|FoundationDB|
@@ -19,11 +17,13 @@ JanusGraph, coupled with the FoundationDB storage adapter provides the following
 
 # Getting started
 
-The FoundationDB storage adapter requires a single FoundatoinDB instance or cluster and the FoundationDB client libraries. Downloads for server and client can be found [here](https://apple.github.io/foundationdb/downloads.html).
+The FoundationDB storage adapter requires a single FoundationDB instance or cluster and the FoundationDB client libraries. Downloads for server and client can be found [here](https://apple.github.io/foundationdb/downloads.html).
 
 ## Setting up FoundationDB
 
-## Installing from a binary release
+Mac install instructions can be found [here](https://apple.github.io/foundationdb/getting-started-mac.html) and Linux [here](https://apple.github.io/foundationdb/getting-started-linux.html).
+
+## Installing the adapter from a binary release
 Binary releases can be found on [GitHub](http://github.com/experoinc/janusgraph-foundationdb/releases).
 
 This installation procedure will copy the necessary libraries, properties, and Gremlin Server configuration files into your JanusGraph installation.
@@ -53,5 +53,8 @@ Follow these steps if you'd like to use the latest version built from source.
 |-|-|-|
 |`storage.fdb.directory`|Name of the JanusGraph storage directory in FoundationDB.|`janusgraph`|
 |`storage.fdb.version`|The FoundationDB client version.|`5.2.0`|
-|`storage.fdb.cluster_file_path`|The location of the `fdb.cluster` file.|`/etc/foundationdb/fdb.cluster`|
-|`storage.fdb.serializable`|JanusGraph transactions are serializable if `true`, read committed if `false`.|`true`|
+|`storage.fdb.cluster-file-path`|The location of the `fdb.cluster` file.|`/etc/foundationdb/fdb.cluster`|
+|`storage.fdb.isolation-level`|The three options are `serializable`, `read_committed_no_write`, and `read_committed_with_write`.|`serializable`|
+
+## Isolation Levels
+FoundationDB provides serializable isolation under a specific set of [constraints](https://apple.github.io/foundationdb/known-limitations.html#current-limitations). Namely transactions will fail if they take longer than 5 seconds or read/write more than 10,000,000 bytes. This adapter allows the user to relax the how JanusGraph uses FoundationDB transactions and to spread a single JanusGraph transaction over more than one FoundationDB transaction. `read_committed_no_write` allows reads to be spread across more than one transasction, but will fail any writes that are attempted outside of the first transaction period. `read_committed_with_write` allows reads and writes to extend over more than one single transaction. If this option is selected, invariants may be broken and the system will behave similarily to an eventually consistent system.

src/main/java/com/experoinc/janusgraph/diskstorage/foundationdb/FoundationDBConfigOptions.java

@@ -49,7 +49,7 @@ public interface FoundationDBConfigOptions {
 
     ConfigOption<String> CLUSTER_FILE_PATH = new ConfigOption<>(
         FDB_NS,
-        "cluster_file_path",
+        "cluster-file-path",
         "Path to the FoundationDB cluster file",
         ConfigOption.Type.LOCAL,
         "default");

src/main/java/com/experoinc/janusgraph/diskstorage/foundationdb/FoundationDBKeyValueStore.java

@@ -87,7 +87,6 @@ public synchronized void close() throws BackendException {
 
     @Override
     public StaticBuffer get(StaticBuffer key, StoreTransaction txh) throws BackendException {
-//        Transaction tx = getTransaction(txh);
         FoundationDBTx tx = getTransaction(txh);
         try {
             byte[] databaseKey = db.pack(key.as(ENTRY_FACTORY));
@@ -118,7 +117,6 @@ public void acquireLock(StaticBuffer key, StaticBuffer expectedValue, StoreTrans
     @Override
     public RecordIterator<KeyValueEntry> getSlice(KVQuery query, StoreTransaction txh) throws BackendException {
         log.trace("beginning db={}, op=getSlice, tx={}", name, txh);
-//        final Transaction tx = getTransaction(txh);
         final FoundationDBTx tx = getTransaction(txh);
         final StaticBuffer keyStart = query.getStart();
         final StaticBuffer keyEnd = query.getEnd();
@@ -176,7 +174,6 @@ public void remove() {
     @Override
     public Map<KVQuery,RecordIterator<KeyValueEntry>> getSlices(List<KVQuery> queries, StoreTransaction txh) throws BackendException {
         log.trace("beginning db={}, op=getSlice, tx={}", name, txh);
-//        final Transaction tx = getTransaction(txh);
         FoundationDBTx tx = getTransaction(txh);
         final Map<KVQuery, RecordIterator<KeyValueEntry>> resultMap = new ConcurrentHashMap<>();
         final List<CompletableFuture<Void>> futures = new ArrayList<>();
@@ -190,18 +187,6 @@ public Map<KVQuery,RecordIterator<KeyValueEntry>> getSlices(List<KVQuery> querie
                 final byte[] foundKey = db.pack(keyStart.as(ENTRY_FACTORY));
                 final byte[] endKey = db.pack(keyEnd.as(ENTRY_FACTORY));
                 preppedQueries.add(new Object[]{query, foundKey, endKey});
-//                    final Transaction tx = getTransaction(txh);
-//                final FoundationDBTx tx = getTransaction(txh);
-//                    r = futures.add(tx.getRange(foundKey, endKey, query.getLimit());
-//                        .thenAccept((r) -> {
-//                            final List<KeyValueEntry> result = new ArrayList<>();
-//                            for (final KeyValue keyValue : r) {
-//                                final StaticBuffer key = getBuffer(db.unpack(keyValue.getKey()).getBytes(0));
-//                                if (selector.include(key))
-//                                    result.add(new KeyValueEntry(key, getBuffer(keyValue.getValue())));
-//                            }
-//                            resultMap.put(query, new FoundationDBRecordIterator(result));
-//                        }));
             }
             final Map<KVQuery, List<KeyValue>> result = tx.getMultiRange(preppedQueries);
 
@@ -215,7 +200,6 @@ public Map<KVQuery,RecordIterator<KeyValueEntry>> getSlices(List<KVQuery> querie
                 resultMap.put(entry.getKey(), new FoundationDBRecordIterator(results));
 
             }
-//            CompletableFuture.allOf(futures.toArray(new CompletableFuture[futures.size()])).join();
         } catch (Exception e) {
             throw new PermanentBackendException(e);
         }
@@ -229,7 +213,6 @@ public void insert(StaticBuffer key, StaticBuffer value, StoreTransaction txh) t
     }
 
     public void insert(StaticBuffer key, StaticBuffer value, StoreTransaction txh, boolean allowOverwrite) throws BackendException {
-//        Transaction tx = getTransaction(txh);
         FoundationDBTx tx = getTransaction(txh);
         try {
 

src/main/java/com/experoinc/janusgraph/diskstorage/foundationdb/FoundationDBTx.java

@@ -23,11 +23,10 @@
 import java.util.concurrent.atomic.AtomicInteger;
 
 /**
- * @author twilmes
+ * @author Ted Wilmes (twilmes@gmail.com)
  */
 public class FoundationDBTx extends AbstractStoreTransaction {
 
-
     private static final Logger log = LoggerFactory.getLogger(FoundationDBTx.class);
 
     private volatile Transaction tx;
@@ -43,7 +42,7 @@ public enum IsolationLevel { SERIALIZABLE, READ_COMMITTED_NO_WRITE, READ_COMMITT
 
     private final IsolationLevel isolationLevel;
 
-    private AtomicInteger txId = new AtomicInteger(0);
+    private AtomicInteger txCtr = new AtomicInteger(0);
 
     public FoundationDBTx(Database db, Transaction t, BaseTransactionConfig config, IsolationLevel isolationLevel) {
         super(config);
@@ -62,7 +61,7 @@ public FoundationDBTx(Database db, Transaction t, BaseTransactionConfig config,
     }
 
     public synchronized void restart() {
-        txId.incrementAndGet();
+        txCtr.incrementAndGet();
         if (tx == null) return;
         try {
             tx.cancel();
@@ -75,7 +74,7 @@ public synchronized void restart() {
         // Reapply mutations but do not clear them out just in case this transaction also
         // times out and they need to be reapplied.
         //
-        // @todo Note that at this point, the too large transaction case (tx exceeds 10,000,000 bytes) is not handled.
+        // @todo Note that at this point, the large transaction case (tx exceeds 10,000,000 bytes) is not handled.
         inserts.forEach(insert -> tx.set(insert.getKey(), insert.getValue()));
         deletions.forEach(delete -> tx.clear(delete));
     }
@@ -171,14 +170,14 @@ public List<KeyValue> getRange(final byte[] startKey, final byte[] endKey,
         boolean failing = true;
         List<KeyValue> result = Collections.emptyList();
         for (int i = 0; i < maxRuns; i++) {
-            final int startTxId = txId.get();
+            final int startTxId = txCtr.get();
             try {
                 result = tx.getRange(new Range(startKey, endKey), limit).asList().get();
                 if (result == null) return Collections.emptyList();
                 failing = false;
                 break;
             } catch (ExecutionException e) {
-                if (txId.get() == startTxId)
+                if (txCtr.get() == startTxId)
                     this.restart();
             } catch (Exception e) {
                 throw new PermanentBackendException(e);
@@ -193,15 +192,15 @@ public List<KeyValue> getRange(final byte[] startKey, final byte[] endKey,
     public synchronized  Map<KVQuery, List<KeyValue>> getMultiRange(final List<Object[]> queries)
             throws PermanentBackendException {
         Map<KVQuery, List<KeyValue>> resultMap = new ConcurrentHashMap<>();
-        List<Object[]> retries = new CopyOnWriteArrayList<>(queries);
-        List<CompletableFuture> futures = new LinkedList<>();
+        final List<Object[]> retries = new CopyOnWriteArrayList<>(queries);
+        final List<CompletableFuture> futures = new LinkedList<>();
         for (int i = 0; i < (maxRuns * 5); i++) {
             for(Object[] obj : retries) {
                 final KVQuery query = (KVQuery) obj[0];
                 final byte[] start = (byte[]) obj[1];
                 final byte[] end = (byte[]) obj[2];
 
-                final int startTxId = txId.get();
+                final int startTxId = txCtr.get();
                 try {
                     futures.add(tx.getRange(start, end, query.getLimit()).asList()
                             .whenComplete((res, th) -> {
@@ -212,7 +211,7 @@ public synchronized  Map<KVQuery, List<KeyValue>> getMultiRange(final List<Objec
                                     }
                                     resultMap.put(query, res);
                                 } else {
-                                    if (startTxId == txId.get())
+                                    if (startTxId == txCtr.get())
                                         this.restart();
                                 }
                             }));
@@ -228,7 +227,6 @@ public synchronized  Map<KVQuery, List<KeyValue>> getMultiRange(final List<Objec
                 // some tasks will fail due to tx time limits being exceeded
             } catch (IllegalStateException is) {
                 // illegal state can arise from tx being closed while tx is inflight
-                // todo find way to clean this up and prevent this state from occurring
             } catch (Exception e) {
                 throw new PermanentBackendException(e);
             }