dcache (pool manager): override suspend when "excluded" (hosts) is no…

…t empty'

Motivation:

In https://rb.dcache.org/r/11955/
master@261e78639548adadfaea38827c47efe92e1a2f41
we introduced support for the xrootd cgi "tried=<host>,".

In https://rb.dcache.org/r/12387/
master@2231b12e451aaa80240eb54861a965c2468d3a99
we made this an optional feature because this exclusion
can put access to the file into an indefinitely
suspended state for all clients.

In this patch, we address the latter problem
directly.

Modfication:

Set a flag on the basis of whether the set
of excluded hosts is empty or not.

In the case of an attempt to suspend access,
if the flag is true, fail instead.

Result:

When 'tried' is activated (the only time
excluded hosts can be non-empty), failure
to read the file will not put the
request container into the SUSPENDED state.

Target: master
Request: 6.1
Patch: https://rb.dcache.org/r/12400
Requires-notes: yes
Requires-book: no
Acked-by: Dmitry

modules/dcache/src/main/java/diskCacheV111/poolManager/RequestContainerV5.java

@@ -25,6 +25,7 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
+import java.util.Set;
 import java.util.concurrent.Callable;
 import java.util.concurrent.Executor;
 import java.util.regex.Pattern;
@@ -857,7 +858,8 @@ private class PoolRequestHandler  {
          * Indicates the next time a TTL of a request message will be
          * exceeded.
          */
-        private long _nextTtlTimeout = Long.MAX_VALUE;
+        private long    _nextTtlTimeout = Long.MAX_VALUE;
+        private boolean _failOnExcluded;
 
         public PoolRequestHandler(PnfsId pnfsId,
                                   String poolGroup,
@@ -919,11 +921,14 @@ public void addRequest( CellMessage message ){
               _destinationFileStatus = ((PoolMgrReplicateFileMsg)request).getDestinationFileStatus() ;
            }
 
+           Set<String> excluded = request.getExcludedHosts();
+           _failOnExcluded = excluded != null && !excluded.isEmpty();
+
            _poolSelector =
                _poolMonitor.getPoolSelector(_fileAttributes,
                        _protocolInfo,
                        _linkGroup,
-                       request.getExcludedHosts());
+                       excluded);
            //
            //
            //
@@ -1816,7 +1821,7 @@ private void suspend(String status)
 
         private void suspendIfEnabled(String status)
         {
-            if (_onError.equals("suspend")) {
+            if (_onError.equals("suspend") && !_failOnExcluded) {
                 suspend(status);
             } else {
                 fail();