[HER-1796] H3: interval rescheduling becomes erratic after URI rescheduled more than maxRetries times

* CrawlURI.java
    improve comments for fetchAttempts methods
    (resetForRescheduling) added to clear per-scheduling state
* WorkQueueFrontier.java
    call resetForRescheduling just before scheduling-at-specific-time
* FrontierJournal.java, AbstractFrontier.java
    renamings: prefer 'reenqueue' instead of 'reschedule' for describing simple (non-timed) retries

engine/src/main/java/org/archive/crawler/frontier/AbstractFrontier.java

@@ -695,10 +695,10 @@ public abstract class AbstractFrontier
         }
     }
 
-    protected void doJournalRescheduled(CrawlURI c) {
+    protected void doJournalReenqueued(CrawlURI c) {
         tally(c,Stage.RETRIED);
         if (this.recover != null) {
-            this.recover.rescheduled(c);
+            this.recover.reenqueued(c);
         }
     }
 

engine/src/main/java/org/archive/crawler/frontier/FrontierJournal.java

@@ -55,7 +55,7 @@ public class FrontierJournal extends CrawlerJournal {
     public final static String F_EMIT = "Fe ";
     public final static String F_INCLUDE = "Fi ";
     public final static String F_DISREGARD = "Fd ";
-    public final static String F_RESCHEDULE = "Fr ";
+    public final static String F_REENQUEUED = "Fr ";
     public final static String F_SUCCESS = "Fs ";
     public final static String F_FAILURE = "Ff ";
     
@@ -117,8 +117,8 @@ public class FrontierJournal extends CrawlerJournal {
         writeLine(F_DISREGARD, curi.toString());
     }
 
-    public void rescheduled(CrawlURI curi) {
-        writeLine(F_RESCHEDULE, curi.toString());
+    public void reenqueued(CrawlURI curi) {
+        writeLine(F_REENQUEUED, curi.toString());
     }
 
     

engine/src/main/java/org/archive/crawler/frontier/WorkQueueFrontier.java

@@ -1019,7 +1019,7 @@ implements Closeable,
             // Let everyone interested know that it will be retried.
             appCtx.publishEvent(
                 new CrawlURIDispositionEvent(this,curi,DEFERRED_FOR_RETRY));
-            doJournalRescheduled(curi);
+            doJournalReenqueued(curi);
             return;
         }
 
@@ -1082,6 +1082,7 @@ implements Closeable,
         if(curi.getRescheduleTime()>0) {
             // marked up for forced-revisit at a set time
             curi.processingCleanup();
+            curi.resetForRescheduling(); 
             futureUris.put(curi.getRescheduleTime(),curi);
             futureUriCount.incrementAndGet(); 
         } else {