Add age: operator to change queries

The age operator looks for changes that have not been modified
within the argument.  E.g. "age:3d" will find changes that haven't
been touched in the last 3 days.

This supports searching for stale changes that maybe need to be
considered for further action.

Change-Id: I35c843099aac7bb795613c5898e84ef0a60f91cc
Signed-off-by: Shawn O. Pearce <sop@google.com>

gerrit-server/src/main/java/com/google/gerrit/server/config/ConfigUtil.java

@@ -140,6 +140,27 @@ public class ConfigUtil {
       return defaultValue;
     }
 
+    try {
+      return getTimeUnit(s, defaultValue, wantUnit);
+    } catch (IllegalArgumentException notTime) {
+      throw notTimeUnit(section, subsection, setting, valueString);
+    }
+  }
+
+  /**
+   * Parse a numerical time unit, such as "1 minute", from a string.
+   *
+   * @param s the string to parse.
+   * @param defaultValue default value to return if no value was set in the
+   *        configuration file.
+   * @param wantUnit the units of {@code defaultValue} and the return value, as
+   *        well as the units to assume if the value does not contain an
+   *        indication of the units.
+   * @return the setting, or {@code defaultValue} if not set, expressed in
+   *         {@code units}.
+   */
+  public static long getTimeUnit(String s, long defaultValue, TimeUnit wantUnit) {
+    final String valueString = s;
     final String unitName;
     final int sp = s.indexOf(' ');
     if (sp > 0) {
@@ -198,13 +219,13 @@ public class ConfigUtil {
       inputMul = 365;
 
     } else {
-      throw notTimeUnit(section, subsection, setting, valueString);
+      throw notTimeUnit(valueString);
     }
 
     try {
       return wantUnit.convert(Long.parseLong(s) * inputMul, inputUnit);
     } catch (NumberFormatException nfe) {
-      throw notTimeUnit(section, subsection, setting, valueString);
+      throw notTimeUnit(valueString);
     }
   }
 
@@ -278,6 +299,10 @@ public class ConfigUtil {
         + valueString);
   }
 
+  private static IllegalArgumentException notTimeUnit(final String val) {
+    return new IllegalArgumentException("Invalid time unit value: " + val);
+  }
+
   private ConfigUtil() {
   }
 }