update 'Collection.toArray()' call style to improve performance in JDK6+

modules/control-utility/src/main/java/org/apache/ignite/internal/commandline/TxCommands.java

@@ -34,6 +34,7 @@
 import org.apache.ignite.internal.commandline.argument.CommandArgUtils;
 import org.apache.ignite.internal.processors.cache.version.GridCacheVersion;
 import org.apache.ignite.internal.util.typedef.F;
+import org.apache.ignite.internal.util.typedef.internal.U;
 import org.apache.ignite.internal.visor.tx.FetchNearXidVersionTask;
 import org.apache.ignite.internal.visor.tx.TxKeyLockType;
 import org.apache.ignite.internal.visor.tx.TxMappingType;
@@ -95,7 +96,7 @@ private String[] getTxOptions() {
         list.add(optional(TX_INFO));
         list.add(optional(CMD_AUTO_CONFIRMATION));
 
-        return list.toArray(new String[list.size()]);
+        return list.toArray(U.EMPTY_STRS);
     }
 
     /** {@inheritDoc} */

modules/core/src/main/java/org/apache/ignite/cache/store/jdbc/dialect/BasicJdbcDialect.java

@@ -21,6 +21,7 @@
 import org.apache.ignite.internal.util.typedef.C1;
 import org.apache.ignite.internal.util.typedef.F;
 import org.apache.ignite.internal.util.typedef.internal.SB;
+import org.apache.ignite.internal.util.typedef.internal.U;
 
 /**
  * Basic implementation of dialect based on JDBC specification.
@@ -175,7 +176,7 @@ private static String where(Collection<String> keyCols, int keyCnt) {
 
         SB sb = new SB();
 
-        String[] cols = keyCols.toArray(new String[keyCols.size()]);
+        String[] cols = keyCols.toArray(U.EMPTY_STRS);
 
         if (appendLowerBound) {
             sb.a("(");

modules/core/src/main/java/org/apache/ignite/configuration/TransactionConfiguration.java

@@ -23,6 +23,7 @@
 import org.apache.ignite.cache.CacheAtomicityMode;
 import org.apache.ignite.internal.util.TransientSerializable;
 import org.apache.ignite.internal.util.typedef.internal.S;
+import org.apache.ignite.internal.util.typedef.internal.U;
 import org.apache.ignite.lang.IgniteExperimental;
 import org.apache.ignite.lang.IgniteProductVersion;
 import org.apache.ignite.transactions.Transaction;
@@ -477,6 +478,6 @@ private static String[] transientSerializableFields(IgniteProductVersion ver) {
         if (DEADLOCK_TIMEOUT_SINCE.compareToIgnoreTimestamp(ver) >= 0)
             transients.add("deadlockTimeout");
 
-        return transients.isEmpty() ? null : transients.toArray(new String[transients.size()]);
+        return transients.isEmpty() ? null : transients.toArray(U.EMPTY_STRS);
     }
 }

modules/core/src/main/java/org/apache/ignite/internal/IgnitionEx.java

@@ -2010,7 +2010,7 @@ public void initializeDefaultCacheConfiguration(IgniteConfiguration cfg) throws
                 }
             }
 
-            cfg.setCacheConfiguration(cacheCfgs.toArray(new CacheConfiguration[cacheCfgs.size()]));
+            cfg.setCacheConfiguration(cacheCfgs.toArray(new CacheConfiguration[0]));
 
             assert cfg.getCacheConfiguration() != null;
         }
@@ -2067,7 +2067,7 @@ private void initializeDefaultSpi(IgniteConfiguration cfg) {
                 if (!dfltLoadBalancingSpi)
                     spis.add(new RoundRobinLoadBalancingSpi());
 
-                cfg.setLoadBalancingSpi(spis.toArray(new LoadBalancingSpi[spis.size()]));
+                cfg.setLoadBalancingSpi(spis.toArray(new LoadBalancingSpi[0]));
             }
 
             if (cfg.getIndexingSpi() == null)
@@ -2682,8 +2682,7 @@ private static void convertLegacyDataStorageConfigurationToNew(
         }
 
         if (!optionalDataRegions.isEmpty())
-            dsCfg.setDataRegionConfigurations(optionalDataRegions.toArray(
-                new DataRegionConfiguration[optionalDataRegions.size()]));
+            dsCfg.setDataRegionConfigurations(optionalDataRegions.toArray(new DataRegionConfiguration[0]));
 
         if (!customDfltPlc) {
             if (!DFLT_MEM_PLC_DEFAULT_NAME.equals(memCfg.getDefaultMemoryPolicyName())) {

modules/core/src/main/java/org/apache/ignite/internal/binary/BinaryClassDescriptor.java

@@ -377,7 +377,7 @@ else if (useOptMarshaller)
                         }
                     }
 
-                    fields = fields0.values().toArray(new BinaryFieldAccessor[fields0.size()]);
+                    fields = fields0.values().toArray(new BinaryFieldAccessor[0]);
 
                     BinarySchema.Builder schemaBuilder = BinarySchema.Builder.newBuilder();
 

modules/core/src/main/java/org/apache/ignite/internal/jdbc/thin/JdbcThinPreparedStatement.java

@@ -274,10 +274,10 @@ private void executeWithArguments(JdbcStatementType stmtType) throws SQLExceptio
             if (batch == null) {
                 batch = new ArrayList<>();
 
-                batch.add(new JdbcQuery(sql, args.toArray(new Object[args.size()])));
+                batch.add(new JdbcQuery(sql, args.toArray(new Object[0])));
             }
             else
-                batch.add(new JdbcQuery(null, args.toArray(new Object[args.size()])));
+                batch.add(new JdbcQuery(null, args.toArray(new Object[0])));
         }
 
         args = null;

modules/core/src/main/java/org/apache/ignite/internal/jdbc/thin/JdbcThinStatement.java

@@ -229,7 +229,7 @@ protected void execute0(JdbcStatementType stmtType, String sql, List<Object> arg
         }
 
         JdbcQueryExecuteRequest req = new JdbcQueryExecuteRequest(stmtType, schema, pageSize,
-            maxRows, conn.getAutoCommit(), explicitTimeout, sql, args == null ? null : args.toArray(new Object[args.size()]));
+            maxRows, conn.getAutoCommit(), explicitTimeout, sql, args == null ? null : args.toArray(new Object[0]));
 
         JdbcResultWithIo resWithIo = conn.sendRequest(req, this, null);
 

modules/core/src/main/java/org/apache/ignite/internal/managers/communication/GridIoManager.java

@@ -478,7 +478,7 @@ public void resetMetrics() {
         }
 
         if (!compMsgs.isEmpty())
-            msgs = F.concat(msgs, compMsgs.toArray(new MessageFactory[compMsgs.size()]));
+            msgs = F.concat(msgs, compMsgs.toArray(new MessageFactory[0]));
 
         msgFactory = new IgniteMessageFactoryImpl(msgs);
 

modules/core/src/main/java/org/apache/ignite/internal/processors/cache/distributed/dht/GridDhtCacheEntry.java

@@ -759,7 +759,7 @@ else if (newRdrs != null)
         }
 
         if (newRdrs != null) {
-            rdrs = newRdrs.toArray(new ReaderId[newRdrs.size()]);
+            rdrs = newRdrs.toArray(ReaderId.EMPTY_ARRAY);
 
             this.rdrs = rdrs;
         }

modules/core/src/main/java/org/apache/ignite/internal/processors/platform/dotnet/PlatformDotNetConfigurationClosure.java

@@ -210,7 +210,7 @@ private void processPrepareResult(BinaryReaderExImpl in) {
         }
 
         if (!newBeans.isEmpty()) {
-            LifecycleBean[] newBeans0 = newBeans.toArray(new LifecycleBean[newBeans.size()]);
+            LifecycleBean[] newBeans0 = newBeans.toArray(new LifecycleBean[0]);
 
             // New beans were added. Let's append them to the tail of the rest configured lifecycle beans.
             LifecycleBean[] oldBeans = cfg.getLifecycleBeans();

modules/core/src/main/java/org/apache/ignite/internal/processors/platform/utils/PlatformConfigurationUtils.java

@@ -289,7 +289,7 @@ public static CacheConfiguration readCacheConfiguration(BinaryRawReaderEx in) {
             if (ccfg.getPluginConfigurations() != null)
                 Collections.addAll(plugins, ccfg.getPluginConfigurations());
 
-            ccfg.setPluginConfigurations(plugins.toArray(new CachePluginConfiguration[plugins.size()]));
+            ccfg.setPluginConfigurations(plugins.toArray(new CachePluginConfiguration[0]));
         }
 
         return ccfg;
@@ -979,7 +979,7 @@ private static void readCacheConfigurations(BinaryRawReaderEx in, IgniteConfigur
             caches.add(readCacheConfiguration(in));
 
         CacheConfiguration[] oldCaches = cfg.getCacheConfiguration();
-        CacheConfiguration[] caches0 = caches.toArray(new CacheConfiguration[caches.size()]);
+        CacheConfiguration[] caches0 = caches.toArray(new CacheConfiguration[0]);
 
         if (oldCaches == null)
             cfg.setCacheConfiguration(caches0);

modules/core/src/main/java/org/apache/ignite/internal/processors/platform/utils/PlatformUtils.java

@@ -481,7 +481,7 @@ public static CachePeekMode[] decodeCachePeekModes(int modes) {
                     res0.add(CachePeekMode.fromOrdinal((byte)i));
             }
 
-            res = res0.toArray(new CachePeekMode[res0.size()]);
+            res = res0.toArray(new CachePeekMode[0]);
 
             synchronized (PlatformUtils.class) {
                 CACHE_PEEK_MODES[modes] = res;

modules/core/src/main/java/org/apache/ignite/internal/processors/resource/GridResourceField.java

@@ -82,7 +82,7 @@ public static GridResourceField[] toArray(Collection<GridResourceField> c) {
         if (c.isEmpty())
             return EMPTY_ARRAY;
 
-        return c.toArray(new GridResourceField[c.size()]);
+        return c.toArray(EMPTY_ARRAY);
     }
 
     /** {@inheritDoc} */

modules/core/src/main/java/org/apache/ignite/internal/processors/resource/GridResourceIoc.java

@@ -307,7 +307,7 @@ class ClassDescriptor {
             }
 
             recursiveFields = recursiveFieldsList.isEmpty() ? U.EMPTY_FIELDS
-                : recursiveFieldsList.toArray(new Field[recursiveFieldsList.size()]);
+                : recursiveFieldsList.toArray(U.EMPTY_FIELDS);
 
             this.annMap = IgniteUtils.limitedMap(annMap.size());
 

modules/core/src/main/java/org/apache/ignite/internal/processors/resource/GridResourceMethod.java

@@ -77,7 +77,7 @@ public static GridResourceMethod[] toArray(Collection<GridResourceMethod> c) {
         if (c.isEmpty())
             return EMPTY_ARRAY;
 
-        return c.toArray(new GridResourceMethod[c.size()]);
+        return c.toArray(EMPTY_ARRAY);
     }
 
     /** {@inheritDoc} */

modules/core/src/main/java/org/apache/ignite/internal/util/IgniteUtils.java

@@ -635,7 +635,7 @@ public abstract class IgniteUtils {
     private static final boolean assertionsEnabled;
 
     /** Empty URL array. */
-    private static final URL[] EMPTY_URL_ARR = new URL[0];
+    public static final URL[] EMPTY_URL_ARR = new URL[0];
 
     /** Builtin class loader class.
      *

modules/core/src/main/java/org/apache/ignite/internal/util/io/GridFilenameUtils.java

@@ -17,6 +17,8 @@
 
 package org.apache.ignite.internal.util.io;
 
+import org.apache.ignite.internal.util.typedef.internal.U;
+
 import java.io.File;
 import java.io.IOException;
 import java.io.Serializable;
@@ -1337,7 +1339,7 @@ else if (list.isEmpty() ||
         if (buffer.length() != 0)
             list.add(buffer.toString());
 
-        return list.toArray( new String[ list.size() ] );
+        return list.toArray(U.EMPTY_STRS);
     }
 
     /**

modules/core/src/main/java/org/apache/ignite/internal/util/nio/GridNioRecoveryDescriptor.java

@@ -254,7 +254,7 @@ public boolean onNodeLeft() {
                 return false;
 
             if (!msgReqs.isEmpty()) {
-                reqs = msgReqs.toArray(new SessionWriteRequest[msgReqs.size()]);
+                reqs = msgReqs.toArray(new SessionWriteRequest[0]);
 
                 msgReqs.clear();
             }
@@ -401,7 +401,7 @@ public void release() {
             }
 
             if (nodeLeft && !msgReqs.isEmpty()) {
-                futs = msgReqs.toArray(new SessionWriteRequest[msgReqs.size()]);
+                futs = msgReqs.toArray(new SessionWriteRequest[0]);
 
                 msgReqs.clear();
             }

modules/core/src/main/java/org/apache/ignite/internal/util/typedef/X.java

@@ -826,7 +826,7 @@ public static List<Throwable> getThrowableList(Throwable throwable) {
     public static Throwable[] getThrowables(Throwable throwable) {
         List<Throwable> list = getThrowableList(throwable);
 
-        return list.toArray(new Throwable[list.size()]);
+        return list.toArray(new Throwable[0]);
     }
 
     /**

modules/core/src/main/java/org/apache/ignite/spi/communication/tcp/internal/GridNioServerWrapper.java

@@ -911,7 +911,7 @@ public GridNioServer<Message> resetNioServer() throws IgniteCheckedException {
                     .directMode(true)
                     .writeTimeout(cfg.socketWriteTimeout())
                     .selectorSpins(cfg.selectorSpins())
-                    .filters(filters.toArray(new GridNioFilter[filters.size()]))
+                    .filters(filters.toArray(new GridNioFilter[0]))
                     .writerFactory(writerFactory)
                     .skipRecoveryPredicate(skipRecoveryPred)
                     .messageQueueSizeListener(queueSizeMonitor)

modules/core/src/main/java/org/apache/ignite/spi/metric/jmx/MetricRegistryMBean.java

@@ -115,7 +115,7 @@ else if (metric instanceof ObjectMetric)
         return new MBeanInfo(
             ReadOnlyMetricManager.class.getName(),
             mreg.name(),
-            attributes.toArray(new MBeanAttributeInfo[attributes.size()]),
+            attributes.toArray(new MBeanAttributeInfo[0]),
             null,
             null,
             null);

modules/core/src/test/java/org/apache/ignite/cache/store/jdbc/CacheJdbcStoreAbstractMultithreadedSelfTest.java

@@ -101,7 +101,7 @@ public abstract class CacheJdbcStoreAbstractMultithreadedSelfTest<T extends Cach
 
             Collection<JdbcType> types = new ArrayList<>(springCtx.getBeansOfType(JdbcType.class).values());
 
-            store.setTypes(types.toArray(new JdbcType[types.size()]));
+            store.setTypes(types.toArray(new JdbcType[0]));
         }
         catch (BeansException e) {
             if (X.hasCause(e, ClassNotFoundException.class))

modules/core/src/test/java/org/apache/ignite/internal/GridProjectionForCachesSelfTest.java

@@ -60,7 +60,7 @@ else if (igniteInstanceName.equals(getTestIgniteInstanceName(2)) ||
             ccfgs.add(cacheConfiguration(CACHE_NAME, new AttributeFilter(getTestIgniteInstanceName(2),
                 getTestIgniteInstanceName(3)), true));
 
-        cfg.setCacheConfiguration(ccfgs.toArray(new CacheConfiguration[ccfgs.size()]));
+        cfg.setCacheConfiguration(ccfgs.toArray(new CacheConfiguration[0]));
 
         return cfg;
     }

modules/core/src/test/java/org/apache/ignite/internal/SensitiveInfoTestLoggerProxy.java

@@ -212,7 +212,7 @@ private static Pattern[] readFromResource(String suffix) {
             ex.printStackTrace();
         }
 
-        return lst.toArray(new Pattern[lst.size()]);
+        return lst.toArray(new Pattern[0]);
     }
 
     /**

modules/core/src/test/java/org/apache/ignite/internal/binary/BinaryEnumsSelfTest.java

@@ -549,7 +549,7 @@ public void testEnumMerge() throws Exception {
                         EnumType.TWO.name(), EnumType.TWO.ordinal()));
 
         Collection<BinaryObject> vals = node1.binary().type(enumName).enumValues();
-        BinaryObject[] values = vals.toArray(new BinaryObject[vals.size()]);
+        BinaryObject[] values = vals.toArray(new BinaryObject[0]);
 
         assertEquals(2, values.length);
 

modules/core/src/test/java/org/apache/ignite/internal/processors/cache/CacheExchangeMessageDuplicatedStateTest.java

@@ -122,7 +122,7 @@ public class CacheExchangeMessageDuplicatedStateTest extends GridCommonAbstractT
             ccfgs.add(ccfg);
         }
 
-        cfg.setCacheConfiguration(ccfgs.toArray(new CacheConfiguration[ccfgs.size()]));
+        cfg.setCacheConfiguration(ccfgs.toArray(new CacheConfiguration[0]));
 
         return cfg;
     }

modules/core/src/test/java/org/apache/ignite/internal/processors/cache/CacheWithDifferentDataRegionConfigurationTest.java

@@ -400,13 +400,13 @@ public IgniteEx start() throws Exception {
             cfg.setConsistentId(gridName);
 
             DataStorageConfiguration storageCfg = new DataStorageConfiguration();
-            storageCfg.setDataRegionConfigurations(regions.toArray(new DataRegionConfiguration[regions.size()]));
+            storageCfg.setDataRegionConfigurations(regions.toArray(new DataRegionConfiguration[0]));
             cfg.setDataStorageConfiguration(storageCfg);
 
             if (dfltRegionConfiguration != null)
                 storageCfg.setDefaultDataRegionConfiguration(dfltRegionConfiguration);
 
-            cfg.setCacheConfiguration(caches.toArray(new CacheConfiguration[caches.size()]));
+            cfg.setCacheConfiguration(caches.toArray(new CacheConfiguration[0]));
 
             return startGrid(cfg);
         }

modules/core/src/test/java/org/apache/ignite/internal/processors/cache/IgniteCachePartitionMapUpdateTest.java

@@ -95,7 +95,7 @@ public class IgniteCachePartitionMapUpdateTest extends GridCommonAbstractTest {
 
         cfg.setUserAttributes(attrs);
 
-        cfg.setCacheConfiguration(ccfgs.toArray(new CacheConfiguration[ccfgs.size()]));
+        cfg.setCacheConfiguration(ccfgs.toArray(new CacheConfiguration[0]));
 
         return cfg;
     }

modules/core/src/test/java/org/apache/ignite/internal/processors/cache/datastructures/IgniteSequenceInternalCleanupTest.java

@@ -68,7 +68,7 @@ public class IgniteSequenceInternalCleanupTest extends GridCommonAbstractTest {
                 setAffinity(new RendezvousAffinityFunction(false, 16)));
         }
 
-        cfg.setCacheConfiguration(cacheCfg.toArray(new CacheConfiguration[cacheCfg.size()]));
+        cfg.setCacheConfiguration(cacheCfg.toArray(new CacheConfiguration[0]));
 
         return cfg;
     }

modules/core/src/test/java/org/apache/ignite/internal/processors/cache/distributed/GridCacheTransformEventSelfTest.java

@@ -571,7 +571,7 @@ else if (cacheMode == REPLICATED) {
             }
         }
 
-        return res.toArray(new UUID[res.size()]);
+        return res.toArray(new UUID[0]);
     }
 
     /**

modules/core/src/test/java/org/apache/ignite/internal/processors/cache/persistence/baseline/ClientAffinityAssignmentWithBaselineTest.java

@@ -149,9 +149,9 @@ public class ClientAffinityAssignmentWithBaselineTest extends GridCommonAbstract
         clientConfigs.add(cacheConfig(PARTITIONED_TX_CLIENT_CACHE_NAME));
 
         if (igniteInstanceName.startsWith(CLIENT_GRID_NAME))
-            cfg.setCacheConfiguration(clientConfigs.toArray(new CacheConfiguration[clientConfigs.size()]));
+            cfg.setCacheConfiguration(clientConfigs.toArray(new CacheConfiguration[0]));
         else
-            cfg.setCacheConfiguration(srvConfigs.toArray(new CacheConfiguration[srvConfigs.size()]));
+            cfg.setCacheConfiguration(srvConfigs.toArray(new CacheConfiguration[0]));
 
         // Enforce different mac adresses to emulate distributed environment by default.
         cfg.setUserAttributes(Collections.singletonMap(

modules/core/src/test/java/org/apache/ignite/internal/processors/cache/persistence/db/checkpoint/IgniteCheckpointDirtyPagesForLowLoadTest.java

@@ -69,7 +69,7 @@ public class IgniteCheckpointDirtyPagesForLowLoadTest extends GridCommonAbstract
                 ccfgs.add(ccfg);
             }
         }
-        cfg.setCacheConfiguration(ccfgs.toArray(new CacheConfiguration[ccfgs.size()]));
+        cfg.setCacheConfiguration(ccfgs.toArray(new CacheConfiguration[0]));
 
         DataStorageConfiguration dsCfg = new DataStorageConfiguration();
         dsCfg.setDefaultDataRegionConfiguration(

modules/core/src/test/java/org/apache/ignite/internal/processors/service/GridServiceProcessorMultiNodeConfigSelfTest.java

@@ -107,7 +107,7 @@ public class GridServiceProcessorMultiNodeConfigSelfTest extends GridServiceProc
 
         cfgs.add(cfg);
 
-        return cfgs.toArray(new ServiceConfiguration[cfgs.size()]);
+        return cfgs.toArray(new ServiceConfiguration[0]);
     }
 
     /** {@inheritDoc} */

modules/dev-utils/src/test/java/org/apache/ignite/development/utils/IgniteWalConverterSensitiveDataTest.java

@@ -46,6 +46,7 @@
 import org.apache.ignite.internal.processors.cache.KeyCacheObjectImpl;
 import org.apache.ignite.internal.processors.cache.version.GridCacheVersion;
 import org.apache.ignite.internal.util.typedef.internal.CU;
+import org.apache.ignite.internal.util.typedef.internal.U;
 import org.apache.ignite.testframework.junits.common.GridCommonAbstractTest;
 import org.apache.ignite.transactions.Transaction;
 import org.junit.Test;
@@ -249,7 +250,7 @@ private void exeWithCheck(
         if (processSensitiveData != null)
             args.add("processSensitiveData=" + processSensitiveData.name());
 
-        IgniteWalConverter.main(args.toArray(new String[args.size()]));
+        IgniteWalConverter.main(args.toArray(U.EMPTY_STRS));
 
         String testOutStr = testOut.toString();