perf(spanner-jdbc): cache positional to named param conversion (#14034)

Cache the result of converting a JDBC SQL string containing positional
parameters (?), so we do not need to do this conversion over and over
each time a SQL string is executed.

Author: olavloite

java-spanner/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/AbstractStatementParser.java

@@ -483,7 +483,13 @@ private static boolean isRecordStatementCacheStats() {
    * Cache for parsed statements. This prevents statements that are executed multiple times by the
    * application to be parsed over and over again. The default maximum size is 5Mb.
    */
-  private final Cache<String, ParsedStatement> statementCache;
+  @Nullable private final Cache<String, ParsedStatement> statementCache;
+
+  /**
+   * Cache for positional parameters info. This prevents statements that are executed multiple times
+   * using positional parameters from having to be scanned and translated repeatedly.
+   */
+  @Nullable private final Cache<String, ParametersInfo> positionalParametersCache;
 
   AbstractStatementParser(Set<ClientSideStatementImpl> statements) {
     this.statements = Collections.unmodifiableSet(statements);
@@ -502,16 +508,36 @@ private static boolean isRecordStatementCacheStats() {
         cacheBuilder.recordStats();
       }
       this.statementCache = cacheBuilder.build();
+
+      CacheBuilder<String, ParametersInfo> positionalCacheBuilder =
+          CacheBuilder.newBuilder()
+              .maximumWeight(maxCacheSize * 1024L * 1024L)
+              .weigher(
+                  (String key, ParametersInfo value) ->
+                      2 * key.length() + 2 * value.sqlWithNamedParameters.length())
+              .concurrencyLevel(Runtime.getRuntime().availableProcessors());
+      if (isRecordStatementCacheStats()) {
+        positionalCacheBuilder.recordStats();
+      }
+      this.positionalParametersCache = positionalCacheBuilder.build();
     } else {
       this.statementCache = null;
+      this.positionalParametersCache = null;
     }
   }
 
   @VisibleForTesting
+  @Nullable
   CacheStats getStatementCacheStats() {
     return statementCache == null ? null : statementCache.stats();
   }
 
+  @VisibleForTesting
+  @Nullable
+  CacheStats getPositionalParametersCacheStats() {
+    return positionalParametersCache == null ? null : positionalParametersCache.stats();
+  }
+
   @VisibleForTesting
   Set<ClientSideStatementImpl> getClientSideStatements() {
     return statements;
@@ -776,8 +802,21 @@ public static class ParametersInfo {
   @InternalApi
   public ParametersInfo convertPositionalParametersToNamedParameters(char paramChar, String sql) {
     Preconditions.checkNotNull(sql);
+    if (positionalParametersCache == null) {
+      return internalConvertPositionalParametersToNamedParameters(paramChar, sql);
+    }
+    String cacheKey = paramChar == '?' ? sql : paramChar + "\0" + sql;
+    ParametersInfo info = positionalParametersCache.getIfPresent(cacheKey);
+    if (info == null) {
+      info = internalConvertPositionalParametersToNamedParameters(paramChar, sql);
+      positionalParametersCache.put(cacheKey, info);
+    }
+    return info;
+  }
+
+  ParametersInfo internalConvertPositionalParametersToNamedParameters(char paramChar, String sql) {
     final String namedParamPrefix = getQueryParameterPrefix();
-    StringBuilder named = new StringBuilder(sql.length() + countOccurrencesOf(paramChar, sql));
+    StringBuilder named = new StringBuilder(sql.length() + 32);
     int index = 0;
     int paramIndex = 1;
     while (index < sql.length()) {

java-spanner/google-cloud-spanner/src/test/java/com/google/cloud/spanner/connection/StatementParserTest.java

@@ -20,6 +20,7 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotSame;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertThrows;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
@@ -29,6 +30,7 @@
 import com.google.cloud.spanner.ErrorCode;
 import com.google.cloud.spanner.SpannerException;
 import com.google.cloud.spanner.Statement;
+import com.google.cloud.spanner.connection.AbstractStatementParser.ParametersInfo;
 import com.google.cloud.spanner.connection.AbstractStatementParser.ParsedStatement;
 import com.google.cloud.spanner.connection.AbstractStatementParser.StatementType;
 import com.google.cloud.spanner.connection.ClientSideStatementImpl.CompileException;
@@ -1864,6 +1866,43 @@ public void testStatementCache_ParameterizedStatement() {
     assertEquals(1, stats.hitCount());
   }
 
+  @Test
+  public void testPositionalParametersCache() {
+    CacheStats statsBefore = parser.getPositionalParametersCacheStats();
+
+    String sql = "select * from foo where id=? and name=? and value=" + UUID.randomUUID();
+    ParametersInfo info1 = parser.convertPositionalParametersToNamedParameters('?', sql);
+    assertEquals(2, info1.numberOfParameters);
+    if (dialect == Dialect.POSTGRESQL) {
+      assertTrue(info1.sqlWithNamedParameters.contains("$1"));
+      assertTrue(info1.sqlWithNamedParameters.contains("$2"));
+    } else {
+      assertTrue(info1.sqlWithNamedParameters.contains("@p1"));
+      assertTrue(info1.sqlWithNamedParameters.contains("@p2"));
+    }
+
+    ParametersInfo info2 = parser.convertPositionalParametersToNamedParameters('?', sql);
+    assertEquals(info1.numberOfParameters, info2.numberOfParameters);
+    assertEquals(info1.sqlWithNamedParameters, info2.sqlWithNamedParameters);
+    assertSame(info1, info2);
+
+    // Test with non-'?' parameter character.
+    String sqlDollar = "select * from foo where id=$ and name=$ and value=" + UUID.randomUUID();
+    ParametersInfo infoDollar1 =
+        parser.convertPositionalParametersToNamedParameters('$', sqlDollar);
+    assertEquals(2, infoDollar1.numberOfParameters);
+    ParametersInfo infoDollar2 =
+        parser.convertPositionalParametersToNamedParameters('$', sqlDollar);
+    assertSame(infoDollar1, infoDollar2);
+
+    CacheStats statsAfter = parser.getPositionalParametersCacheStats();
+    CacheStats stats = statsAfter.minus(statsBefore);
+
+    // Two distinct queries had cache misses. Two repeated queries had cache hits.
+    assertEquals(2, stats.missCount());
+    assertEquals(2, stats.hitCount());
+  }
+
   @Test
   public void testClientSideStatementWithComment() {
     String sql = "-- Null (no timeout)\n" + "SET STATEMENT_TIMEOUT=null";