Merge pull request #189 from fanson/perf/zero-alloc-parsing

perf: cache command string and add zero-allocation integer parsing

Author: tonivade

src/main/java/com/github/tonivade/resp/command/DefaultRequest.java

@@ -11,7 +11,7 @@
 
 public class DefaultRequest implements Request {
 
-  private final SafeString command;
+  private final String command;
 
   private final List<SafeString> params;
 
@@ -22,13 +22,13 @@ public class DefaultRequest implements Request {
   public DefaultRequest(ServerContext server, Session session, SafeString command, List<SafeString> params) {
     this.server = server;
     this.session = session;
-    this.command = checkNonNull(command);
+    this.command = checkNonNull(command).toString();
     this.params = checkNonNull(params);
   }
 
   @Override
   public String getCommand() {
-    return command.toString();
+    return command;
   }
 
   @Override
@@ -61,7 +61,7 @@ public boolean isEmpty() {
 
   @Override
   public boolean isExit() {
-    return command.toString().equalsIgnoreCase("quit");
+    return getCommand().equalsIgnoreCase("quit");
   }
 
   @Override

src/main/java/com/github/tonivade/resp/protocol/RedisParser.java

@@ -60,7 +60,7 @@ private RedisToken parseToken(SafeString line) {
     RedisToken token = new UnknownRedisToken(SafeString.EMPTY_STRING);
     if (line != null && !line.isEmpty()) {
       if (line.startsWith(ARRAY_PREFIX)) {
-        int size = Integer.parseInt(line.substring(1));
+        int size = line.parseIntAfterPrefix();
         token = parseArray(size);
       } else if (line.startsWith(STATUS_PREFIX)) {
         token = status(line.substring(1));
@@ -78,13 +78,12 @@ private RedisToken parseToken(SafeString line) {
   }
 
   private RedisToken parseIntegerToken(SafeString line) {
-    Integer value = Integer.valueOf(line.substring(1));
-    return new IntegerRedisToken(value);
+    return new IntegerRedisToken(line.parseIntAfterPrefix());
   }
 
   private RedisToken parseStringToken(SafeString line) {
     StringRedisToken token;
-    int length = Integer.parseInt(line.substring(1));
+    int length = line.parseIntAfterPrefix();
     if (length >= 0 && length < maxLength) {
       token = new StringRedisToken(source.readString(length));
     } else {

src/main/java/com/github/tonivade/resp/protocol/SafeString.java

@@ -120,6 +120,26 @@ public String substring(int i) {
     return toString().substring(i);
   }
 
+  public int parseIntAfterPrefix() {
+    int pos = buffer.position();
+    int lim = buffer.limit();
+    boolean negative = false;
+    int result = 0;
+    int start = pos + 1;
+    if (start < lim && buffer.get(start) == '-') {
+      negative = true;
+      start++;
+    }
+    for (int i = start; i < lim; i++) {
+      byte b = buffer.get(i);
+      if (b < '0' || b > '9') {
+        throw new NumberFormatException("Invalid character in number: " + (char) b);
+      }
+      result = result * 10 + (b - '0');
+    }
+    return negative ? -result : result;
+  }
+
   private static int compare(byte[] left, byte[] right) {
     for (int i = 0, j = 0; i < left.length && j < right.length; i++, j++) {
       int a = (left[i] & 0xff);

src/test/java/com/github/tonivade/resp/command/DefaultRequestTest.java

@@ -8,6 +8,7 @@
 import static com.github.tonivade.resp.protocol.SafeString.safeString;
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.CoreMatchers.nullValue;
+import static org.hamcrest.CoreMatchers.sameInstance;
 import static org.hamcrest.MatcherAssert.assertThat;
 
 import org.junit.jupiter.api.Test;
@@ -31,4 +32,27 @@ void testRequest() {
     assertThat(request.getOptionalParam(3).isPresent(), is(false));
     assertThat(request.toString(), is("a[3]: [1, 2, 3]"));
   }
+
+  @Test
+  void getCommandReturnsCachedInstance() {
+    DefaultRequest request = new DefaultRequest(null, null, safeString("PING"),
+                                                safeAsList());
+
+    String first = request.getCommand();
+    String second = request.getCommand();
+
+    assertThat(first, is("PING"));
+    assertThat(second, sameInstance(first));
+  }
+
+  @Test
+  void isExitUsesCache() {
+    DefaultRequest quit = new DefaultRequest(null, null, safeString("QUIT"),
+                                             safeAsList());
+    DefaultRequest ping = new DefaultRequest(null, null, safeString("PING"),
+                                             safeAsList());
+
+    assertThat(quit.isExit(), is(true));
+    assertThat(ping.isExit(), is(false));
+  }
 }

src/test/java/com/github/tonivade/resp/protocol/SafeStringTest.java

@@ -9,6 +9,7 @@
 import static com.github.tonivade.resp.protocol.SafeString.safeString;
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.util.Iterator;
 import java.util.List;
@@ -41,6 +42,39 @@ void testList() {
     assertThat(list.get(2), is(safeString("3")));
   }
 
+  @Test
+  void parseIntAfterPrefixPositive() {
+    assertThat(safeString("*3").parseIntAfterPrefix(), is(3));
+    assertThat(safeString("$123").parseIntAfterPrefix(), is(123));
+    assertThat(safeString(":42").parseIntAfterPrefix(), is(42));
+  }
+
+  @Test
+  void parseIntAfterPrefixNegative() {
+    assertThat(safeString(":-1").parseIntAfterPrefix(), is(-1));
+    assertThat(safeString("$-1").parseIntAfterPrefix(), is(-1));
+    assertThat(safeString(":-999").parseIntAfterPrefix(), is(-999));
+  }
+
+  @Test
+  void parseIntAfterPrefixZero() {
+    assertThat(safeString("$0").parseIntAfterPrefix(), is(0));
+    assertThat(safeString(":0").parseIntAfterPrefix(), is(0));
+  }
+
+  @Test
+  void parseIntAfterPrefixLargeNumber() {
+    assertThat(safeString("*100000").parseIntAfterPrefix(), is(100000));
+    assertThat(safeString(":2147483647").parseIntAfterPrefix(), is(Integer.MAX_VALUE));
+  }
+
+  @Test
+  void parseIntAfterPrefixInvalidCharacter() {
+    assertThrows(NumberFormatException.class, () -> safeString("*abc").parseIntAfterPrefix());
+    assertThrows(NumberFormatException.class, () -> safeString("$12x").parseIntAfterPrefix());
+    assertThrows(NumberFormatException.class, () -> safeString(":1.5").parseIntAfterPrefix());
+  }
+
   @Test
   void testSet() {
     NavigableSet<SafeString> set = new TreeSet<>(safeAsList("1", "2", "3"));