Continue unrolling and inlining value parser. Make targeted use of ByteBuffer.getInt() instead of ByteBuffer.get(). Switch from GraalVM CE to GraalVM. (#201)

calculate_average_ebarlas.sh

@@ -16,6 +16,6 @@
 #
 
 source "$HOME/.sdkman/bin/sdkman-init.sh"
-sdk use java 21.0.1-graalce 1>&2
+sdk use java 21.0.1-graal 1>&2
 JAVA_OPTS=""
 time java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_ebarlas measurements.txt 8

src/main/java/dev/morling/onebrc/CalculateAverage_ebarlas.java

@@ -18,6 +18,7 @@ package dev.morling.onebrc;
 import java.io.IOException;
 import java.nio.BufferUnderflowException;
 import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
 import java.nio.channels.FileChannel;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Paths;
@@ -28,7 +29,7 @@ import java.util.TreeMap;
 
 public class CalculateAverage_ebarlas {
 
-    private static final int MAX_KEY_SIZE = 100 * 4; // max 4 bytes per UTF-8 char
+    private static final int MAX_KEY_SIZE = 100;
     private static final int HASH_FACTOR = 433;
     private static final int HASH_TBL_SIZE = 16_383; // range of allowed hash values, inclusive
 
@@ -52,7 +53,7 @@ public class CalculateAverage_ebarlas {
             var pSize = pEnd - pStart;
             Runnable r = () -> {
                 try {
-                    var buffer = channel.map(FileChannel.MapMode.READ_ONLY, pStart, pSize);
+                    var buffer = channel.map(FileChannel.MapMode.READ_ONLY, pStart, pSize).order(ByteOrder.LITTLE_ENDIAN);
                     partitions[pIdx] = processBuffer(buffer, pIdx == 0);
                 }
                 catch (IOException e) {
@@ -113,7 +114,7 @@ public class CalculateAverage_ebarlas {
             var merged = mergeFooterAndHeader(pPrev.footer, pNext.header);
             if (merged != null) {
                 if (merged[merged.length - 1] == '\n') { // fold into prev partition
-                    doProcessBuffer(ByteBuffer.wrap(merged), true, pPrev.stats);
+                    doProcessBuffer(ByteBuffer.wrap(merged).order(ByteOrder.LITTLE_ENDIAN), true, pPrev.stats);
                 }
                 else { // no newline appeared in partition, carry forward
                     pNext.footer = merged;
@@ -142,23 +143,42 @@ public class CalculateAverage_ebarlas {
     private static Partition doProcessBuffer(ByteBuffer buffer, boolean first, Stats[] stats) {
         var header = first ? null : readHeader(buffer);
         var keyStart = reallyDoProcessBuffer(buffer, stats);
-        var footer = keyStart < buffer.position() ? readFooter(buffer, keyStart) : null;
+        var footer = keyStart < buffer.limit() ? readFooter(buffer, keyStart) : null;
         return new Partition(header, footer, stats);
     }
 
     private static int reallyDoProcessBuffer(ByteBuffer buffer, Stats[] stats) {
         var keyBuf = new byte[MAX_KEY_SIZE]; // buffer for key
-        var keyPos = 0; // current position in key buffer
+        int keyStart = 0; // start of key in buffer used for footer calc
-        var keyHash = 0; // accumulating hash of key
+        try { // abort with exception to allow optimistic line processing
-        var keyStart = buffer.position(); // start of key in buffer used for footer calc
+            while (true) { // one line per iteration
-        try { // abort with exception to avoid hasRemaining() calls
+                keyStart = buffer.position(); // preserve line start
-            while (true) {
+                int n = buffer.getInt(); // first four bytes of key
-                var b = buffer.get();
+                byte b1 = (byte) (n & 0xFF);
-                if (b != ';') {
+                byte b2 = (byte) ((n >> 8) & 0xFF);
+                byte b3 = (byte) ((n >> 16) & 0xFF);
+                byte b = (byte) ((n >> 24) & 0xFF);
+                int keyPos;
+                int keyHash = keyBuf[0] = b1;
+                if (b2 != ';' && b3 != ';') { // true for keys of length 3 or more
+                    keyBuf[1] = b2;
+                    keyBuf[2] = b3;
+                    keyHash = HASH_FACTOR * (HASH_FACTOR * keyHash + b2) + b3;
+                    keyPos = 3;
+                    while (b != ';') {
+                        keyHash = HASH_FACTOR * keyHash + b;
+                        keyBuf[keyPos++] = b;
+                        b = buffer.get();
+                    }
+                }
+                else { // slow path, rewind and consume byte-by-byte
+                    buffer.position(keyStart + 1);
+                    keyPos = 1;
+                    while ((b = buffer.get()) != ';') {
                         keyHash = HASH_FACTOR * keyHash + b;
                         keyBuf[keyPos++] = b;
                     }
-                else {
+                }
                 var idx = keyHash & HASH_TBL_SIZE;
                 var st = stats[idx];
                 if (st == null) { // nothing in table, eagerly claim spot
@@ -167,31 +187,46 @@ public class CalculateAverage_ebarlas {
                 else if (!Arrays.equals(st.key, 0, st.key.length, keyBuf, 0, keyPos)) {
                     st = findInTable(stats, keyHash, keyBuf, keyPos);
                 }
-                    var negative = false;
+                var value = buffer.getInt();
-                    b = buffer.get(); // digit or dash
+                b = (byte) (value & 0xFF); // digit or dash
-                    if (b == '-') {
+                int val;
-                        negative = true;
+                if (b == '-') { // dash branch
-                        b = buffer.get(); // digit after neg
+                    val = ((byte) ((value >> 8) & 0xFF)) - '0'; // digit after dash
+                    b = (byte) ((value >> 16) & 0xFF); // second digit or decimal
+                    if (b != '.') { // second digit
+                        val = val * 10 + (b - '0'); // calc second digit
+                        // skip decimal (at >> 24)
+                        b = buffer.get(); // digit after decimal
+                        val = val * 10 + (b - '0'); // calc digit after decimal
                     }
-                    var val = b - '0';
+                    else { // decimal branch
-                    b = buffer.get(); // second digit or decimal
+                           // skip decimal (at >> 16)
-                    if (b != '.') {
+                        b = (byte) ((value >> 24) & 0xFF); // digit after decimal
-                        val = val * 10 + (b - '0');
+                        val = val * 10 + (b - '0'); // calc digit after decimal
-                        buffer.get(); // decimal
                     }
-                    val = val * 10 + (buffer.get() - '0'); // digit after decimal
                     buffer.get(); // newline
-                    var v = negative ? -val : val;
+                    val = -val;
-                    st.min = Math.min(st.min, v);
-                    st.max = Math.max(st.max, v);
-                    st.sum += v;
-                    st.count++;
-                    keyStart = buffer.position(); // preserve line start
-                    b = buffer.get(); // first byte of key
-                    keyHash = b;
-                    keyBuf[0] = b;
-                    keyPos = 1;
                 }
+                else { // first digit branch
+                    val = b - '0'; // calc first digit
+                    b = (byte) ((value >> 8) & 0xFF); // second digit or decimal
+                    if (b != '.') { // second digit branch
+                        val = val * 10 + (b - '0'); // calc second digit
+                        // skip decimal (at >> 16)
+                        b = (byte) ((value >> 24) & 0xFF); // digit after decimal
+                        val = val * 10 + (b - '0'); // calc digit after decimal
+                        buffer.get(); // newline
+                    }
+                    else { // decimal branch
+                        b = (byte) ((value >> 16) & 0xFF); // digit after decimal
+                        val = val * 10 + (b - '0'); // calc digit after decimal
+                        // skip newline (at >> 24)
+                    }
+                }
+                st.min = Math.min(st.min, val);
+                st.max = Math.max(st.max, val);
+                st.sum += val;
+                st.count++;
             }
         }
         catch (BufferUnderflowException ignore) {
@@ -220,7 +255,7 @@ public class CalculateAverage_ebarlas {
     }
 
     private static byte[] readFooter(ByteBuffer buffer, int lineStart) { // read from line start to current pos (end-of-input)
-        var footer = new byte[buffer.position() - lineStart];
+        var footer = new byte[buffer.limit() - lineStart];
         buffer.get(lineStart, footer, 0, footer.length);
         return footer;
     }