Commented Java code

diff --git a/doc/iotcloud.tex b/doc/iotcloud.tex
index 4d0c9f491dbc12085ed551a060fe60188663992b..fd8a719aa5d1b71a5832356eaa621817777377ed 100644 (file)
--- a/doc/iotcloud.tex
+++ b/doc/iotcloud.tex
@@ -228,7 +228,6 @@ $Slot(SL_s,s_s)= \tuple{s, sv}$ \textit{such that} $\tuple{s, sv}
 $SeqN(\tuple{s, sv})=s$ \\\r
 $SlotVal(\tuple{s, sv})=sv$ \\\r
 $CreateLastSL(s,sv,id)=\tuple{s,sv,id}=sl_{last}$ \\\r
-$CreateEntLV(kv_s,s_s)=\tuple{kv_s,s_s}$ \\\r
 $Decrypt(SK_s,sv_s)=Dat_s=\tuple{s,id,hmac_p,DE,hmac_c}$ \\\r
 $GetSeqN(Dat_s = \tuple{s,id,hmac_p,DE,hmac_c})=s$ \\\r
 $GetMacId(Dat_s = \tuple{s,id,hmac_p,DE,hmac_c})=id$ \\\r
@@ -272,7 +271,7 @@ $MaxSMSeqN(SM_s)= s$ \textit{such that} $\tuple{s, id} \in SM_s
 \begin{algorithmic}[1]\r
 \Function{GetQueSta}{$DE_s$}\r
 \State $de_{qs} \gets ss$ \textit{such that} $ss \in DE_s, \r
-       de_s \in D \land type(de_s) = "qs"$\r
+       de_s \in D \land type(de_s) = ``qs"$\r
 \If{$de_{qs} \neq \emptyset$}\r
        \State $qs_{ret} \gets GetQS(de_{qs})$\r
 \Else\r
@@ -284,14 +283,14 @@ $MaxSMSeqN(SM_s)= s$ \textit{such that} $\tuple{s, id} \in SM_s
 \r
 \begin{algorithmic}[1]\r
 \Function{GetSlotSeq}{$DE_s$}\r
-\State $DE_{ss} \gets \{de | de \in DE_s \land type(de) = "ss"\}$\r
+\State $DE_{ss} \gets \{de | de \in DE_s \land type(de) = ``ss"\}$\r
 \State \Return{$DE_{ss}$}\r
 \EndFunction\r
 \end{algorithmic}\r
 \r
 \begin{algorithmic}[1]\r
 \Function{GetColRes}{$DE_s$}\r
-\State $DE_{cr} \gets \{de | de \in DE_s \land type(de) = "cr"\}$\r
+\State $DE_{cr} \gets \{de | de \in DE_s \land type(de) = ``cr"\}$\r
 \State \Return{$DE_{cr}$}\r
 \EndFunction\r
 \end{algorithmic}\r
@@ -449,7 +448,7 @@ $MaxSMSeqN(SM_s)= s$ \textit{such that} $\tuple{s, id} \in SM_s
 \r
 \begin{algorithmic}[1]\r
 \Function{UpdateDT}{$DT_s,DE_s,LV_s,s_s$}\r
-\State $DE_{s_{kv}} \gets \{de_s | de_s \in DE_s, type(de_s) = "kv"\}$\r
+\State $DE_{s_{kv}} \gets \{de_s | de_s \in DE_s, type(de_s) = ``kv"\}$\r
 \ForAll{$de_s \in DE_s$}\r
        \State $kv_s \gets GetKV(de_s)$\r
        \State $LV_s \gets \Call{UpdateKVLivEnt}{LV_s,kv_s,s_s}$\r
@@ -663,16 +662,16 @@ $\tuple{ck,\tuple{k, v}} \in KV_s \wedge
 \ForAll{$de_s \in DE_s$}\r
        \State $live \gets \Call{CheckLiveness}{s_s,de_s}$\r
        \If{$live$}\r
-               \If{$de_s = kv$}\r
+               \If{$type(de_s) = ``kv"$}\r
                        \State $\tuple{k_s,v_s} \gets GetKV(de_s)$\r
                        \State $KV \gets \Call{PutKVPair}{KV,\tuple{k_s,v_s}}$\r
-               \ElsIf{$de_s = ss$}\r
+               \ElsIf{$type(de_s) = ``ss"$}\r
                        \State $\tuple{id_s,s_{s_{last}}} \gets GetSS(de_s)$\r
                        \State $SS \gets \Call{PutSSPair}{SS,\tuple{id_s,s_{s_{last}}}}$\r
-               \ElsIf{$de_s = cr$}\r
+               \ElsIf{$type(de_s) = ``cr"$}\r
                        \State $\tuple{s_s,id_s} \gets GetCR(de_s)$\r
                        \State $CR \gets \Call{PutCRPair}{CR,\tuple{s_s,id_s}}$\r
-               \ElsIf{$de_s = qs$}\r
+               \ElsIf{$type(de_s) = ``qs"$}\r
                        \State $reinsert_{qs} \gets true$\r
                \EndIf\r
        \EndIf\r

diff --git a/src/java/iotcloud/SlotBuffer.java b/src/java/iotcloud/SlotBuffer.java
index ac9dee1540bd07dd172ec4a39406660dbb64acab..14bc926b3c5bedc5e7530ccc212cca2d89237aaa 100644 (file)
--- a/src/java/iotcloud/SlotBuffer.java
+++ b/src/java/iotcloud/SlotBuffer.java
@@ -1,7 +1,7 @@
 package iotcloud;
 
 /**
- * Buffer that holds the live set of slots.
+ * Circular buffer that holds the live set of slots.
  * @author Brian Demsky
  * @version 1.0
  */

diff --git a/src/java/iotcloud/Table.java b/src/java/iotcloud/Table.java
index 7c798ad7679c63f1dbfa2859973faf95129dcd40..1d6259a2a31649c680fe2b401e441ade86529493 100644 (file)
--- a/src/java/iotcloud/Table.java
+++ b/src/java/iotcloud/Table.java
@@ -14,17 +14,22 @@ import java.util.Random;
  */
 
 final public class Table {
-       private int numslots;
+       private int numslots;   //number of slots stored in buffer
+
+       //table of key-value pairs
        private HashMap<IoTString, KeyValue> table=new HashMap<IoTString, KeyValue>();
+
+       // machine id -> (sequence number, Slot or LastMessage); records last message by each client
        private HashMap<Long, Pair<Long, Liveness> > lastmessagetable=new HashMap<Long, Pair<Long, Liveness> >();
+       // machine id -> ...
        private HashMap<Long, HashSet<RejectedMessage> > watchlist = new HashMap<Long, HashSet<RejectedMessage> >();
        private Vector<Long> rejectedmessagelist=new Vector<Long>();
        private SlotBuffer buffer;
        private CloudComm cloud;
-       private long sequencenumber;
+       private long sequencenumber; //Largest sequence number a client has received
        private long localmachineid;
        private TableStatus lastTableStatus;
-       static final int FREE_SLOTS = 10;
+       static final int FREE_SLOTS = 10; //number of slots that should be kept free
        static final int SKIP_THRESHOLD = 10;
        private long liveslotcount=0;
        private int chance;
@@ -32,7 +37,7 @@ final public class Table {
        static final double RESIZE_THRESHOLD = 0.75;
        static final int REJECTED_THRESHOLD = 5;
        private int resizethreshold;
-       private long lastliveslotseqn;
+       private long lastliveslotseqn;  //smallest sequence number with a live entry
        private Random random=new Random();
        
        public Table(String baseurl, String password, long _localmachineid) {
@@ -108,6 +113,7 @@ final public class Table {
                liveslotcount--;
        }
        
+       
        private void setResizeThreshold() {
                int resize_lower=(int) (RESIZE_THRESHOLD * numslots);
                resizethreshold=resize_lower-1+random.nextInt(numslots-resize_lower);
@@ -116,9 +122,8 @@ final public class Table {
        private boolean tryput(IoTString key, IoTString value, boolean resize) {
                Slot s=new Slot(this, sequencenumber+1, localmachineid, buffer.getSlot(sequencenumber).getHMAC());
                int newsize = 0;
-               if (liveslotcount > resizethreshold) {
-                       resize=true;
-                       newsize = (int) (numslots * RESIZE_MULTIPLE);
+               if (liveslotcount > resizethreshold) { 
+                       resize=true; //Resize is forced
                }
                
                if (resize) {
@@ -127,7 +132,7 @@ final public class Table {
                        s.addEntry(status);
                }
 
-               if (!rejectedmessagelist.isEmpty()) {
+               if (! rejectedmessagelist.isEmpty()) {
                        /* TODO: We should avoid generating a rejected message entry if
                         * there is already a sufficient entry in the queue (e.g.,
                         * equalsto value of true and same sequence number).  */
@@ -138,13 +143,13 @@ final public class Table {
                                RejectedMessage rm=new RejectedMessage(s, localmachineid, old_seqn, new_seqn, false);
                                s.addEntry(rm);
                        } else {
-                               long prev_seqn=-1;
+                               long prev_seqn = -1;
                                int i=0;
                                /* Go through list of missing messages */
-                               for(;i<rejectedmessagelist.size();i++) {
-                                       long curr_seqn=rejectedmessagelist.get(i);
-                                       Slot s_msg=buffer.getSlot(curr_seqn);
-                                       if (s_msg!=null)
+                               for(; i<rejectedmessagelist.size(); i++) {
+                                       long curr_seqn = rejectedmessagelist.get(i);
+                                       Slot s_msg = buffer.getSlot(curr_seqn);
+                                       if (s_msg != null)
                                                break;
                                        prev_seqn=curr_seqn;
                                }
@@ -154,7 +159,7 @@ final public class Table {
                                        s.addEntry(rm);
                                }
                                /* Generate rejected message entries for present messages */
-                               for(;i<rejectedmessagelist.size();i++) {
+                               for(; i<rejectedmessagelist.size(); i++) {
                                        long curr_seqn=rejectedmessagelist.get(i);
                                        Slot s_msg=buffer.getSlot(curr_seqn);
                                        long machineid=s_msg.getMachineID();
@@ -171,25 +176,25 @@ final public class Table {
 
                long seqn = lastliveslotseqn;
                boolean seenliveslot = false;
-               long firstiffull = newestseqnum + 1 - numslots;
-               long threshold = firstiffull + FREE_SLOTS;
+               long firstiffull = newestseqnum + 1 - numslots; //smallest seq number in the buffer if it is full
+               long threshold = firstiffull + FREE_SLOTS;      //we want the buffer to be clear of live entries up to this point
                
                for(; seqn < threshold; seqn++) {
                        Slot prevslot=buffer.getSlot(seqn);
                        //Push slot number forward
-                       if (!seenliveslot)
+                       if (! seenliveslot)
                                lastliveslotseqn = seqn;
 
-                       if (!prevslot.isLive())
+                       if (! prevslot.isLive())
                                continue;
                        seenliveslot = true;
                        Vector<Entry> liveentries = prevslot.getLiveEntries(resize);
                        for(Entry liveentry:liveentries) {
                                if (s.hasSpace(liveentry)) {
                                        s.addEntry(liveentry);
-                               } else if (seqn==firstiffull) {
+                               } else if (seqn==firstiffull) {   //if there's no space but the entry is about to fall off the queue
                                        if (!resize) {
-                                               System.out.print("B");
+                                               System.out.print("B"); //?
                                                return tryput(key, value, true);
                                        }
                                }
@@ -203,6 +208,9 @@ final public class Table {
                        insertedkv=true;
                }
 
+               /* now go through live entries from least to greatest sequence number until
+                * either all live slots added, or the slot doesn't have enough room
+                * for SKIP_THRESHOLD consecutive entries*/
                int skipcount=0;
                search:
                for(; seqn <= newestseqnum; seqn++) {
@@ -249,8 +257,7 @@ final public class Table {
        private void validateandupdate(Slot[] newslots, boolean acceptupdatestolocal) {
                /* The cloud communication layer has checked slot HMACs already
                         before decoding */
-               if (newslots.length==0)
-                       return;
+               if (newslots.length==0) return;
 
                long firstseqnum=newslots[0].getSequenceNumber();
                if (firstseqnum <= sequencenumber)
@@ -259,7 +266,7 @@ final public class Table {
                SlotIndexer indexer = new SlotIndexer(newslots, buffer);
                checkHMACChain(indexer, newslots);
 
-               HashSet<Long> machineSet=new HashSet<Long>(lastmessagetable.keySet());
+               HashSet<Long> machineSet=new HashSet<Long>(lastmessagetable.keySet());  //
 
                initExpectedSize(firstseqnum);
                for(Slot slot: newslots) {
@@ -293,7 +300,7 @@ final public class Table {
 
        private void initExpectedSize(long firstsequencenumber) {
                long prevslots = firstsequencenumber;
-               expectedsize = (prevslots < ((long) numslots))?(int) prevslots:numslots;
+               expectedsize = (prevslots < ((long) numslots))? (int) prevslots : numslots;
                currmaxsize = numslots;
        }
 
@@ -333,18 +340,18 @@ final public class Table {
                long newseqnum=entry.getNewSeqNum();
                boolean isequal=entry.getEqual();
                long machineid=entry.getMachineID();
-               for(long seqnum=oldseqnum; seqnum<=newseqnum; seqnum++) {
+               for(long seqnum=oldseqnum; seqnum <= newseqnum; seqnum++) {
                        Slot slot=indexer.getSlot(seqnum);
                        if (slot != null) {
                                long slotmachineid=slot.getMachineID();
-                               if (isequal!=(slotmachineid==machineid)) {
+                               if (isequal != (slotmachineid==machineid)) {
                                        throw new Error("Server Error: Trying to insert rejected message for slot "+seqnum);
                                }
                        }
                }
 
                HashSet<Long> watchset=new HashSet<Long>();
-               for(Map.Entry<Long, Pair<Long,Liveness> > lastmsg_entry:lastmessagetable.entrySet()) {
+               for(Map.Entry<Long, Pair<Long,Liveness> > lastmsg_entry : lastmessagetable.entrySet()) {
                        long entry_mid=lastmsg_entry.getKey();
                        /* We've seen it, don't need to continue to watch.  Our next
                         * message will implicitly acknowledge it. */