add ThreadPool::isIdle() to avoid incorrect detection of "no tasks"

Tasks that are being worked on but are not yet finished are removed
from maTasks, so maTasks.empty() does not mean "idle". I fixed one
case already in 2ad4e77a0f266ae6e6fccaebb1d080d2880bdac3, this one
fixes joinAll() which has a similar problem and triggers
https://gerrit.libreoffice.org/c/core/+/69473/3/sc/source/core/data/documen2.cxx#312

Also rename joinAll() to joinThreadsIfIdle(), as that's what it really is.

Change-Id: I8129cfadb81be968575ea8718de9ae997b877a4e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/106701
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>
(cherry picked from commit 583b0612696f42571ac97b66c159570ea452fe17)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/106824

1 files changed, 6 insertions, 3 deletions

diff --git a/include/comphelper/threadpool.hxx b/include/comphelper/threadpool.hxx
index f51daf4f70a4..ec128b1422bd 100644
--- a/include/comphelper/threadpool.hxx
+++ b/include/comphelper/threadpool.hxx
@@ -64,12 +64,15 @@ public:
     void        pushTask( std::unique_ptr<ThreadTask> pTask);
 
     /** Wait until all queued tasks associated with the tag are completed
-        @param  bJoinAll - if set it joins all threads at the end if no other tasks from other tags.
+        @param  bJoin - if set call joinThreadsIfIdle() at the end
     */
-    void        waitUntilDone(const std::shared_ptr<ThreadTaskTag>&, bool bJoinAll = true);
+    void        waitUntilDone(const std::shared_ptr<ThreadTaskTag>&, bool bJoin = true);
 
     /// join all threads if there are no tasks presently.
-    void        joinAll();
+    void        joinThreadsIfIdle();
+
+    /// return true if there are no queued or worked-on tasks
+    bool        isIdle() const { return maTasks.empty() && mnBusyWorkers == 0; };
 
     /// return the number of live worker threads
     sal_Int32   getWorkerCount() const { return mnMaxWorkers; }