Merge pull request #1132 from katzyn/visitor

Reduce allocation of ExpressionVisitor instances

h2/src/main/org/h2/command/dml/Select.java

@@ -1435,20 +1435,18 @@ public class Select extends Query {
         default:
         }
         ExpressionVisitor v2 = visitor.incrementQueryLevel(1);
-        boolean result = true;
         for (Expression e : expressions) {
             if (!e.isEverything(v2)) {
-                result = false;
-                break;
+                return false;
             }
         }
-        if (result && condition != null && !condition.isEverything(v2)) {
-            result = false;
+        if (condition != null && !condition.isEverything(v2)) {
+            return false;
         }
-        if (result && having != null && !having.isEverything(v2)) {
-            result = false;
+        if (having != null && !having.isEverything(v2)) {
+            return false;
         }
-        return result;
+        return true;
     }
 
     @Override

h2/src/main/org/h2/expression/ExpressionVisitor.java

@@ -61,6 +61,37 @@ public class ExpressionVisitor {
     public static final ExpressionVisitor EVALUATABLE_VISITOR =
             new ExpressionVisitor(EVALUATABLE);
 
+    /**
+     * Count of cached INDEPENDENT and EVALUATABLE visitors with different query
+     * level.
+     */
+    private static final int CACHED = 8;
+
+    /**
+     * INDEPENDENT listeners with query level 0, 1, ...
+     */
+    private static final ExpressionVisitor[] INDEPENDENT_VISITORS;
+
+    /**
+     * EVALUATABLE listeners with query level 0, 1, ...
+     */
+    private static final ExpressionVisitor[] EVALUATABLE_VISITORS;
+
+    static {
+        ExpressionVisitor[] a = new ExpressionVisitor[CACHED];
+        a[0] = INDEPENDENT_VISITOR;
+        for (int i = 1; i < CACHED; i++) {
+            a[i] = new ExpressionVisitor(INDEPENDENT, i);
+        }
+        INDEPENDENT_VISITORS = a;
+        a = new ExpressionVisitor[CACHED];
+        a[0] = EVALUATABLE_VISITOR;
+        for (int i = 1; i < CACHED; i++) {
+            a[i] = new ExpressionVisitor(EVALUATABLE, i);
+        }
+        EVALUATABLE_VISITORS = a;
+    }
+
     /**
      * Request to set the latest modification id (addDataModificationId).
      */
@@ -148,6 +179,17 @@ public class ExpressionVisitor {
         this.maxDataModificationId = null;
     }
 
+    private ExpressionVisitor(int type, int queryLevel) {
+        this.type = type;
+        this.queryLevel = queryLevel;
+        this.dependencies = null;
+        this.columns1 = null;
+        this.columns2 = null;
+        this.table = null;
+        this.resolver = null;
+        this.maxDataModificationId = null;
+    }
+
     /**
      * Create a new visitor object to collect dependencies.
      *
@@ -245,11 +287,18 @@ public class ExpressionVisitor {
      * Increment or decrement the query level.
      *
      * @param offset 1 to increment, -1 to decrement
-     * @return a clone of this expression visitor, with the changed query level
+     * @return this visitor or its clone with the changed query level
      */
     public ExpressionVisitor incrementQueryLevel(int offset) {
-        return new ExpressionVisitor(type, queryLevel + offset, dependencies,
-                columns1, table, resolver, maxDataModificationId, columns2);
+        if (type == INDEPENDENT) {
+            offset += queryLevel;
+            return offset < CACHED ? INDEPENDENT_VISITORS[offset] : new ExpressionVisitor(INDEPENDENT, offset);
+        } else if (type == EVALUATABLE) {
+            offset += queryLevel;
+            return offset < CACHED ? EVALUATABLE_VISITORS[offset] : new ExpressionVisitor(EVALUATABLE, offset);
+        } else {
+            return this;
+        }
     }
 
     /**
@@ -287,6 +336,7 @@ public class ExpressionVisitor {
     }
 
     int getQueryLevel() {
+        assert type == INDEPENDENT || type == EVALUATABLE;
         return queryLevel;
     }
 

h2/src/test/org/h2/test/TestBase.java

@@ -45,6 +45,7 @@ import org.h2.test.utils.ProxyCodeGenerator;
 import org.h2.test.utils.ResultVerifier;
 import org.h2.test.utils.SelfDestructor;
 import org.h2.tools.DeleteDbFiles;
+import org.h2.util.Utils;
 
 /**
  * The base class for all tests.
@@ -140,7 +141,14 @@ public abstract class TestBase {
             init(conf);
             start = System.nanoTime();
             test();
-            println("");
+            if (!config.mvStore) {
+                /*
+                 * This code is here to debug memory issues with PageStore testing on Travis.
+                 */
+                println("(" + (Utils.getMemoryUsed() >> 10) + " MiB used after)");
+            } else {
+                println("");
+            }
         } catch (Throwable e) {
             println("FAIL " + e.toString());
             logError("FAIL " + e.toString(), e);

h2/src/test/org/h2/test/synth/TestFuzzOptimizations.java

@@ -18,6 +18,7 @@ import java.util.Random;
 import org.h2.test.TestBase;
 import org.h2.test.db.Db;
 import org.h2.test.db.Db.Prepared;
+import org.h2.util.Utils;
 
 /**
  * This test executes random SQL statements to test if optimizations are working
@@ -102,12 +103,12 @@ public class TestFuzzOptimizations extends TestBase {
         int size = getSize(100, 1000);
         for (int i = 0; i < size; i++) {
             long seed = seedGenerator.nextLong();
-            println("seed: " + seed);
+            println("testIn() seed: " + seed);
             Random random = new Random(seed);
             ArrayList<String> params = new ArrayList<>();
             String condition = getRandomCondition(random, params, columns,
                     compares, values);
-            String message = "seed: " + seed + " " + condition;
+            String message = "testIn() seed: " + seed + " " + condition;
             executeAndCompare(condition, params, message);
             if (params.size() > 0) {
                 for (int j = 0; j < params.size(); j++) {
@@ -116,9 +117,16 @@ public class TestFuzzOptimizations extends TestBase {
                 }
                 executeAndCompare(condition, params, message);
             }
+            if (!config.mvStore) {
+                /*
+                 * Travis tests have problems with automatic garbage collection, so request a GC
+                 * explicitly and print its results.
+                 */
+                println((Utils.getMemoryUsed() >> 10) + " MiB used");
+            }
         }
         executeAndCompare("a >=0 and b in(?, 2) and a in(1, ?, null)", Arrays.asList("10", "2"),
-                "seed=-6191135606105920350L");
+                "testIn() seed=-6191135606105920350L");
         db.execute("drop table test0, test1");
     }
 
@@ -192,7 +200,7 @@ public class TestFuzzOptimizations extends TestBase {
         db.execute("UPDATE TEST SET B = NULL WHERE B = 0");
         Random random = new Random();
         long seed = random.nextLong();
-        println("seed: " + seed);
+        println("testInSelect() seed: " + seed);
         for (int i = 0; i < 100; i++) {
             String column = random.nextBoolean() ? "A" : "B";
             String value = new String[] { "NULL", "0", "A", "B" }[random.nextInt(4)];
@@ -206,7 +214,7 @@ public class TestFuzzOptimizations extends TestBase {
                 " FROM TEST I WHERE I." + compare + "=?) ORDER BY 1, 2";
             List<Map<String, Object>> a = db.prepare(sql1).set(x).query();
             List<Map<String, Object>> b = db.prepare(sql2).set(x).query();
-            assertTrue("seed: " + seed + " sql: " + sql1 +
+            assertTrue("testInSelect() seed: " + seed + " sql: " + sql1 +
                     " a: " + a + " b: " + b, a.equals(b));
         }
         db.execute("DROP TABLE TEST");
@@ -217,7 +225,7 @@ public class TestFuzzOptimizations extends TestBase {
         db.execute("CREATE TABLE TEST(A INT, B INT, C INT)");
         Random random = new Random();
         long seed = random.nextLong();
-        println("seed: " + seed);
+        println("testGroupSorted() seed: " + seed);
         for (int i = 0; i < 100; i++) {
             Prepared p = db.prepare("INSERT INTO TEST VALUES(?, ?, ?)");
             p.set(new String[] { null, "0", "1", "2" }[random.nextInt(4)]);