Add retry mechanism to CompoundRateProvider.getExchangeRate on failure

Modified the getExchangeRate method in the CompoundRateProvider class to introduce a failFast parameter.

Previously, the method would immediately throw an exception on the first provider failure. This change allows for a more flexible approach by adding an option to continue attempting to get an exchange rate from subsequent providers if failFast is set to false.

- Added a new overloaded getExchangeRate method with a failFast boolean parameter.
- If failFast is true, the method retains the original behavior of failing immediately on the first exception.
- If failFast is false, the method logs a warning and continues to the next provider in case of an exception.

This update addresses some of the limitations described in issue #385.

Author: sernamar

moneta-core/pom.xml

@@ -216,6 +216,13 @@
 	</dependencyManagement>
 
 	<dependencies>
+		<dependency>
+			<groupId>org.javamoney</groupId>
+			<artifactId>moneta</artifactId>
+			<version>1.4.4</version>
+			<type>pom</type>
+			<scope>test</scope>
+		</dependency>
 		<dependency>
 			<groupId>javax.money</groupId>
 			<artifactId>money-api</artifactId>

moneta-core/src/main/java/org/javamoney/moneta/spi/CompoundRateProvider.java

@@ -28,6 +28,7 @@
 import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
+import java.util.logging.Logger;
 
 /**
  * This class implements a {@link ExchangeRateProvider} that delegates calls to
@@ -48,6 +49,8 @@ public class CompoundRateProvider extends AbstractRateProvider {
      */
     private final List<ExchangeRateProvider> providers = new ArrayList<>();
 
+    private static final Logger logger = Logger.getLogger(CompoundRateProvider.class.getName());
+
     /**
      * Constructor.
      *
@@ -102,6 +105,10 @@ private void addProvider(ExchangeRateProvider prov) {
      */
     @Override
     public ExchangeRate getExchangeRate(ConversionQuery conversionQuery) {
+        return getExchangeRate(conversionQuery, false);
+    }
+
+    public ExchangeRate getExchangeRate(ConversionQuery conversionQuery, boolean failFast) {
         for (ExchangeRateProvider prov : this.providers) {
             try {
                 if (prov.isAvailable(conversionQuery)) {
@@ -111,15 +118,18 @@ public ExchangeRate getExchangeRate(ConversionQuery conversionQuery) {
                     }
                 }
             } catch (Exception e) {
-                throw new CurrencyConversionException(conversionQuery.getBaseCurrency(), conversionQuery.getCurrency(), null,
-                    "Rate Provider did not return data though at check before data was flagged as available," +
-                        " provider=" + prov.getContext().getProviderName() + ", query=" + conversionQuery, e);
+                if (failFast) {
+                    throw new CurrencyConversionException(conversionQuery.getBaseCurrency(), conversionQuery.getCurrency(), null,
+                            "Rate Provider did not return data though at check before data was flagged as available," +
+                                    " provider=" + prov.getContext().getProviderName() + ", query=" + conversionQuery, e);
+                } else {
+                    logger.warning("Rate Provider did not return data though at check before data was flagged as available," +
+                            " provider=" + prov.getContext().getProviderName() + ", query=" + conversionQuery + ", error=" + e.getMessage());
+                }
             }
         }
         throw new CurrencyConversionException(conversionQuery.getBaseCurrency(), conversionQuery.getCurrency(), null,
                 "All delegate providers failed to deliver rate, providers=" + this.providers +
                         ", query=" + conversionQuery);
     }
-
-
-}
+}

moneta-core/src/test/java/org/javamoney/moneta/spi/CompoundRateProviderTest.java

@@ -0,0 +1,66 @@
+package org.javamoney.moneta.spi;
+
+import org.testng.annotations.Test;
+
+import javax.money.convert.*;
+
+import java.time.DayOfWeek;
+import java.time.LocalDate;
+import java.time.temporal.TemporalAdjusters;
+
+import static org.testng.Assert.*;
+
+public class CompoundRateProviderTest {
+
+    @Test
+    public void testGetExchangeRate() {
+        String baseCurrency = "EUR";
+        String termCurrency = "GBP";
+        LocalDate date = lastWeekTuesday();
+        ConversionQuery conversionQuery = ConversionQueryBuilder.of()
+                .setBaseCurrency(baseCurrency)
+                .setTermCurrency(termCurrency)
+                .set(date)
+                .build();
+
+        ExchangeRateProvider compoundRateProvider = MonetaryConversions.getExchangeRateProvider("ECB", "ECB-HIST90");
+        assertNotNull(compoundRateProvider.getExchangeRate(conversionQuery));
+    }
+
+    @Test
+    public void testGetExchangeRateAllProvidersFail() {
+        String baseCurrency = "EUR";
+        String termCurrency = "GBP";
+        LocalDate date = lastWeekTuesday();
+        ConversionQuery conversionQuery = ConversionQueryBuilder.of()
+                .setBaseCurrency(baseCurrency)
+                .setTermCurrency(termCurrency)
+                .set(date)
+                .build();
+
+        ExchangeRateProvider compoundRateProvider = MonetaryConversions.getExchangeRateProvider("ECB", "IMF");
+        assertThrows(CurrencyConversionException.class, () -> compoundRateProvider.getExchangeRate(conversionQuery));
+    }
+
+    @Test
+    public void testGetExchangeRateFailingFast() {
+        String baseCurrency = "EUR";
+        String termCurrency = "GBP";
+        LocalDate date = lastWeekTuesday();
+        ConversionQuery conversionQuery = ConversionQueryBuilder.of()
+                .setBaseCurrency(baseCurrency)
+                .setTermCurrency(termCurrency)
+                .set(date)
+                .build();
+
+        // Need to cast to CompoundRateProvider to access the getExchangeRate method that takes a boolean parameter
+        CompoundRateProvider compoundRateProvider = (CompoundRateProvider) MonetaryConversions.getExchangeRateProvider("ECB", "ECB-HIST90");
+        assertThrows(CurrencyConversionException.class, () -> compoundRateProvider.getExchangeRate(conversionQuery, true));
+    }
+
+    private LocalDate lastWeekTuesday() {
+        LocalDate today = LocalDate.now();
+        LocalDate lastTuesday = today.with(TemporalAdjusters.previousOrSame(DayOfWeek.TUESDAY));
+        return lastTuesday.minusWeeks(1);
+    }
+}