DATACOUCH-158 - Allow more explicit expiry unit

The Document annotation now also support explicitly giving a TimeUnit for the expiry, ensuring the framework will correctly convert that to the expected Couchbase format.

src/main/java/org/springframework/data/couchbase/core/mapping/BasicCouchbasePersistentEntity.java

@@ -16,6 +16,10 @@
 
 package org.springframework.data.couchbase.core.mapping;
 
+import java.util.Calendar;
+import java.util.TimeZone;
+import java.util.concurrent.TimeUnit;
+
 import com.couchbase.client.java.repository.annotation.Id;
 
 import org.springframework.beans.BeansException;
@@ -95,15 +99,28 @@ public class BasicCouchbasePersistentEntity<T> extends BasicPersistentEntity<T,
     return super.returnPropertyIfBetterIdPropertyCandidateOrNull(property);
   }
 
-  /**
-   * Returns the expiration time of the entity.
-   *
-   * @return the expiration time.
-   */
+  @Override
   public int getExpiry() {
     org.springframework.data.couchbase.core.mapping.Document annotation =
         getType().getAnnotation(org.springframework.data.couchbase.core.mapping.Document.class);
-    return annotation == null ? 0 : annotation.expiry();
+    if (annotation == null)
+      return 0;
+
+    long secondsShift = annotation.expiryUnit().toSeconds(annotation.expiry());
+    if (secondsShift > TTL_IN_SECONDS_INCLUSIVE_END) {
+      //we want it to be represented as a UNIX timestamp style, seconds since Epoch in UTC
+      Calendar cal = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
+      if (annotation.expiryUnit() == TimeUnit.DAYS) {
+        //makes sure we won't lose resolution
+        cal.add(Calendar.DAY_OF_MONTH, annotation.expiry());
+      } else {
+        //use the shift in seconds since resolution should be smaller
+        cal.add(Calendar.SECOND, (int) secondsShift);
+      }
+      return (int) (cal.getTimeInMillis() / 1000); //note: Unix UTC time representation in int is okay until year 2038
+    } else {
+      return (int) secondsShift;
+    }
   }
 
 }

src/main/java/org/springframework/data/couchbase/core/mapping/CouchbaseDocument.java

@@ -225,6 +225,9 @@ public class CouchbaseDocument implements CouchbaseStorable {
    * <p/>
    * If the expiration time is 0, then the document will be persisted until
    * deleted manually ("forever").
+   * <p/>
+   * Expiration should be expressed as seconds if <= 30 days (30 x 24 x 60 x 60 seconds),
+   * or as an expiry date (UTC, UNIX time ie. seconds form the Epoch) if > 30 days.
    *
    * @param expiration
    * @return the {@link CouchbaseDocument} for chaining.

src/main/java/org/springframework/data/couchbase/core/mapping/CouchbasePersistentEntity.java

@@ -27,9 +27,18 @@ public interface CouchbasePersistentEntity<T> extends
     PersistentEntity<T, CouchbasePersistentProperty> {
 
   /**
-   * Returns the expiry time for the document.
+   * The threshold (inclusive) after which expiry should be expressed as a Unix UTC time.
+   */
+  long TTL_IN_SECONDS_INCLUSIVE_END = 30 * 24 * 60 * 60;
+
+  /**
+   * Returns the expiration time of the entity.
+   * <p/>
+   * The Couchbase format for expiration time is:
+   *  - for TTL < 31 days (<= 30 * 24 * 60 * 60): expressed as a TTL in seconds
+   *  - for TTL > 30 days: expressed as Unix UTC time of expiry (number of SECONDS since the Epoch)
    *
-   * @return the expiration time.
+   * @return the expiration time in correct Couchbase format.
    */
   int getExpiry();
 

src/main/java/org/springframework/data/couchbase/core/mapping/Document.java

@@ -21,6 +21,7 @@ import java.lang.annotation.Inherited;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
+import java.util.concurrent.TimeUnit;
 
 import org.springframework.data.annotation.Persistent;
 
@@ -36,8 +37,13 @@ import org.springframework.data.annotation.Persistent;
 public @interface Document {
 
   /**
-   * An optional expiry time for the document.
+   * An optional expiry time for the document. Default is no expiry.
    */
   int expiry() default 0;
 
+  /**
+   * An optional time unit for the document's {@link #expiry()}, if set. Default is {@link TimeUnit#SECONDS}.
+   */
+  TimeUnit expiryUnit() default TimeUnit.SECONDS;
+
 }