⚡️ Speed up method User.hashCode by 18%

[codeflash-ai]

📄 18% (0.18x) speedup for User.hashCode in client/src/com/aerospike/client/admin/User.java

⏱️ Runtime : 3.81 microseconds → 3.23 microseconds (best of 179 runs)

📝 Explanation and details

The change reduces hashCode runtime from 3.81 microseconds to 3.23 microseconds (≈17% faster). It replaces the multi-step computation with a single conditional that reads name into a local variable and returns (n == null) ? 31 : (n.hashCode() + 31), removing the temporary result, one multiplication, and repeated field loads. Fewer loads and arithmetic reduce instruction count on the hot path and let the JIT optimize the local value more effectively, yielding the measured speedup. The only trade-off is a slightly denser one-line return expression versus the original multi-statement form, with no behavioral changes observed in tests.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 21 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
📊 Tests Coverage	100.0%

🌀 Click to see Generated Regression Tests

package com.aerospike.client.admin;

import org.junit.Test;
import org.junit.Before;
import static org.junit.Assert.*;
import com.aerospike.client.admin.User;
// Performance comparison:
// UserTest.testUnicodeName_ComputesCorrectly#11: 0.000ms -> 0.000ms (-22.2% faster)
// UserTest.testEmptyName_Returns31PlusEmptyStringHash#2: 0.000ms -> 0.000ms (6.2% faster)
// UserTest.testSameName_TwoInstances_SameHashCode#4: 0.000ms -> 0.000ms (12.7% faster)
// UserTest.testSameName_TwoInstances_SameHashCode#5: 0.000ms -> 0.000ms (2.0% faster)
// UserTest.testNullName_Returns31#1: 0.000ms -> 0.000ms (-21.5% faster)
// UserTest.testDifferentNames_TypicallyDifferentHashCodes#6: 0.000ms -> 0.000ms (21.6% faster)
// UserTest.testDifferentNames_TypicallyDifferentHashCodes#7: 0.000ms -> 0.000ms (16.1% faster)
// UserTest.testStability_MultipleCalls_ReturnsSameValue#8: 0.000ms -> 0.000ms (28.4% faster)
// UserTest.testStability_MultipleCalls_ReturnsSameValue#9: 0.000ms -> 0.000ms (43.5% faster)
// UserTest.testStability_MultipleCalls_ReturnsSameValue#10: 0.000ms -> 0.000ms (53.8% faster)
// UserTest.testTypicalName_ComputesAs31PlusNameHash#3: 0.000ms -> 0.000ms (22.1% faster)
// UserTest.testLargeName_PerformanceAndCorrectness#12: 0.000ms -> 0.000ms (7.3% faster)
// UserTest.testSameNameDifferentInstances_sameHashCode#4: 0.000ms -> 0.000ms (31.0% faster)
// UserTest.testSameNameDifferentInstances_sameHashCode#5: 0.000ms -> 0.000ms (9.8% faster)
// UserTest.testUnicodeName_hashMatches#9: 0.000ms -> 0.000ms (18.0% faster)
// UserTest.testNameEmptyString_returns31#2: 0.000ms -> 0.000ms (18.0% faster)
// UserTest.testDifferentNames_differentHashCodes#6: 0.000ms -> 0.000ms (30.3% faster)
// UserTest.testDifferentNames_differentHashCodes#7: 0.000ms -> 0.000ms (-2.5% faster)
// UserTest.testVeryLongName_hashComputedCorrectly#8: 0.000ms -> 0.000ms (15.5% faster)
// UserTest.testTypicalName_hashEquals31PlusNameHash#3: 0.000ms -> 0.000ms (8.3% faster)
// UserTest.testNameNull_returns31#1: 0.000ms -> 0.000ms (8.6% faster)

/**
 * Unit tests for com.aerospike.client.admin.User.hashCode()
 */
public class UserTest {
    private User instance;

    @Before
    public void setUp() {
        instance = new User();
    }

    @Test
    public void testNullName_Returns31() {
        // Default instance.name is null
        instance.name = null;
        int expected = 31; // 31 * 1 + 0
        assertEquals("hashCode should be 31 when name is null", expected, instance.hashCode());
    }

    @Test
    public void testEmptyName_Returns31PlusEmptyStringHash() {
        instance.name = "";
        int expected = 31 + "".hashCode(); // "" hashCode() == 0, so expected == 31
        assertEquals("hashCode should equal 31 + \"\".hashCode()", expected, instance.hashCode());
    }

    @Test
    public void testTypicalName_ComputesAs31PlusNameHash() {
        instance.name = "alice";
        int expected = 31 + "alice".hashCode();
        assertEquals("hashCode should be 31 + name.hashCode()", expected, instance.hashCode());
    }

    @Test
    public void testSameName_TwoInstances_SameHashCode() {
        User u1 = new User();
        User u2 = new User();
        u1.name = "bob";
        u2.name = "bob";
        int h1 = u1.hashCode();
        int h2 = u2.hashCode();
        assertEquals("Two users with same name should have equal hashCodes", h1, h2);
    }

    @Test
    public void testDifferentNames_TypicallyDifferentHashCodes() {
        User u1 = new User();
        User u2 = new User();
        u1.name = "alice";
        u2.name = "bob";
        int h1 = u1.hashCode();
        int h2 = u2.hashCode();
        // It's theoretically possible (but extremely unlikely) for these to collide.
        // We assert they are different for typical cases.
        assertTrue("Different names should typically produce different hashCodes", h1 != h2);
    }

    @Test
    public void testStability_MultipleCalls_ReturnsSameValue() {
        instance.name = "stable";
        int first = instance.hashCode();
        int second = instance.hashCode();
        int third = instance.hashCode();
        assertEquals("hashCode should be stable across multiple calls", first, second);
        assertEquals("hashCode should be stable across multiple calls", first, third);
    }

    @Test
    public void testUnicodeName_ComputesCorrectly() {
        instance.name = "名😊"; // unicode characters
        int expected = 31 + "名😊".hashCode();
        assertEquals("hashCode should handle unicode names correctly", expected, instance.hashCode());
    }

    @Test
    public void testLargeName_PerformanceAndCorrectness() {
        // Build a large name string (10k characters). This verifies method handles large inputs.
        StringBuilder sb = new StringBuilder(10000);
        for (int i = 0; i < 10000; i++) {
            sb.append((char) ('a' + (i % 26)));
        }
        String largeName = sb.toString();
        instance.name = largeName;
        int expected = 31 + largeName.hashCode();
        assertEquals("hashCode should compute correctly for large name", expected, instance.hashCode());
    }
}

To edit these changes git checkout codeflash/optimize-User.hashCode-mmcof5jf and push.