Drill 4313 - Improve method of picking a random drillbit from the C++ client

contrib/native/client/src/clientlib/drillClient.cpp

@@ -38,6 +38,7 @@ DrillClientError* DrillClientError::getErrorObject(const exec::shared::DrillPBEr
 
 DrillClientInitializer::DrillClientInitializer(){
     GOOGLE_PROTOBUF_VERIFY_VERSION;
+    srand(time(NULL));
 }
 
 DrillClientInitializer::~DrillClientInitializer(){

contrib/native/client/src/clientlib/drillClientImpl.cpp

@@ -49,7 +49,7 @@
 namespace Drill{
 
 static std::map<exec::shared::QueryResult_QueryState, status_t> QUERYSTATE_TO_STATUS_MAP = boost::assign::map_list_of
-    (exec::shared::QueryResult_QueryState_PENDING, QRY_PENDING)
+    (exec::shared::QueryResult_QueryState_STARTING, QRY_PENDING)
     (exec::shared::QueryResult_QueryState_RUNNING, QRY_RUNNING)
     (exec::shared::QueryResult_QueryState_COMPLETED, QRY_COMPLETED)
     (exec::shared::QueryResult_QueryState_CANCELED, QRY_CANCELED)
@@ -647,7 +647,7 @@ status_t DrillClientImpl::processQueryResult(AllocatedBufferPtr  allocatedBuffer
 
         if (qr.has_query_state() &&
                 qr.query_state() != exec::shared::QueryResult_QueryState_RUNNING &&
-                qr.query_state() != exec::shared::QueryResult_QueryState_PENDING) {
+                qr.query_state() != exec::shared::QueryResult_QueryState_STARTING) {
             pDrillClientQueryResult=findQueryResult(qid);
             //Queries that have been cancelled or whose resources are freed before completion 
             //do not have a DrillClientQueryResult object. We need not handle the terminal message 
@@ -1397,7 +1397,6 @@ char ZookeeperImpl::s_defaultCluster[]="drillbits1";
 
 ZookeeperImpl::ZookeeperImpl(){
     m_pDrillbits=new String_vector;
-    srand (time(NULL));
     m_bConnecting=true;
     memset(&m_id, 0, sizeof(m_id));
 }
@@ -1468,10 +1467,17 @@ int ZookeeperImpl::connectToZookeeper(const char* connectStr, const char* pathTo
 
     //Let's pick a random drillbit.
     if(m_pDrillbits && m_pDrillbits->count >0){
-        int r=rand()%(this->m_pDrillbits->count);
-        assert(r<this->m_pDrillbits->count);
-        char * bit=this->m_pDrillbits->data[r];
+
+        std::vector<std::string> randomDrillbits;
+        for(int i=0; i<m_pDrillbits->count; i++){
+            randomDrillbits.push_back(m_pDrillbits->data[i]);
+        }
+        //Use the same random shuffle as the Java client instead of picking a drillbit at random.
+        //Gives much better randomization when the size of the cluster is small.
+        std::random_shuffle(randomDrillbits.begin(), randomDrillbits.end());
+        const char * bit=randomDrillbits[0].c_str();
         std::string s;
+
         s=rootDir +  std::string("/") + bit;
         int buffer_len=MAX_CONNECT_STR;
         char buffer[MAX_CONNECT_STR+1];

contrib/native/client/src/clientlib/drillClientImpl.hpp

@@ -28,6 +28,7 @@
 #define BOOST_ASIO_ENABLE_CANCELIO
 #endif //WIN32_SHUTDOWN_ON_TIMEOUT
 
+#include <algorithm>
 #include <stdlib.h>
 #include <time.h>
 #include <queue>
@@ -71,7 +72,7 @@ class DrillClientQueryResult{
         m_bHasSchemaChanged(false),
         m_bHasData(false),
         m_bHasError(false),
-        m_queryState(exec::shared::QueryResult_QueryState_PENDING),
+        m_queryState(exec::shared::QueryResult_QueryState_STARTING),
         m_pError(NULL),
         m_pQueryId(NULL),
         m_pSchemaListener(NULL),
@@ -205,7 +206,6 @@ class DrillClientImpl{
             m_rbuf(NULL),
             m_wbuf(MAX_SOCK_RD_BUFSIZE)
     {
-        srand(time(NULL));
         m_coordinationId=rand()%1729+1;
     };